Root/fs/ext4/inode.c

1/*
2 * linux/fs/ext4/inode.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * from
10 *
11 * linux/fs/minix/inode.c
12 *
13 * Copyright (C) 1991, 1992 Linus Torvalds
14 *
15 * Goal-directed block allocation by Stephen Tweedie
16 * (sct@redhat.com), 1993, 1998
17 * Big-endian to little-endian byte-swapping/bitmaps by
18 * David S. Miller (davem@caip.rutgers.edu), 1995
19 * 64-bit file support on 64-bit platforms by Jakub Jelinek
20 * (jj@sunsite.ms.mff.cuni.cz)
21 *
22 * Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23 */
24
25#include <linux/module.h>
26#include <linux/fs.h>
27#include <linux/time.h>
28#include <linux/jbd2.h>
29#include <linux/highuid.h>
30#include <linux/pagemap.h>
31#include <linux/quotaops.h>
32#include <linux/string.h>
33#include <linux/buffer_head.h>
34#include <linux/writeback.h>
35#include <linux/pagevec.h>
36#include <linux/mpage.h>
37#include <linux/namei.h>
38#include <linux/uio.h>
39#include <linux/bio.h>
40
41#include "ext4_jbd2.h"
42#include "xattr.h"
43#include "acl.h"
44#include "ext4_extents.h"
45
46#include <trace/events/ext4.h>
47
48#define MPAGE_DA_EXTENT_TAIL 0x01
49
50static inline int ext4_begin_ordered_truncate(struct inode *inode,
51                          loff_t new_size)
52{
53    return jbd2_journal_begin_ordered_truncate(
54                    EXT4_SB(inode->i_sb)->s_journal,
55                    &EXT4_I(inode)->jinode,
56                    new_size);
57}
58
59static void ext4_invalidatepage(struct page *page, unsigned long offset);
60
61/*
62 * Test whether an inode is a fast symlink.
63 */
64static int ext4_inode_is_fast_symlink(struct inode *inode)
65{
66    int ea_blocks = EXT4_I(inode)->i_file_acl ?
67        (inode->i_sb->s_blocksize >> 9) : 0;
68
69    return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
70}
71
72/*
73 * The ext4 forget function must perform a revoke if we are freeing data
74 * which has been journaled. Metadata (eg. indirect blocks) must be
75 * revoked in all cases.
76 *
77 * "bh" may be NULL: a metadata block may have been freed from memory
78 * but there may still be a record of it in the journal, and that record
79 * still needs to be revoked.
80 *
81 * If the handle isn't valid we're not journaling, but we still need to
82 * call into ext4_journal_revoke() to put the buffer head.
83 */
84int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
85        struct buffer_head *bh, ext4_fsblk_t blocknr)
86{
87    int err;
88
89    might_sleep();
90
91    BUFFER_TRACE(bh, "enter");
92
93    jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
94          "data mode %x\n",
95          bh, is_metadata, inode->i_mode,
96          test_opt(inode->i_sb, DATA_FLAGS));
97
98    /* Never use the revoke function if we are doing full data
99     * journaling: there is no need to, and a V1 superblock won't
100     * support it. Otherwise, only skip the revoke on un-journaled
101     * data blocks. */
102
103    if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
104        (!is_metadata && !ext4_should_journal_data(inode))) {
105        if (bh) {
106            BUFFER_TRACE(bh, "call jbd2_journal_forget");
107            return ext4_journal_forget(handle, bh);
108        }
109        return 0;
110    }
111
112    /*
113     * data!=journal && (is_metadata || should_journal_data(inode))
114     */
115    BUFFER_TRACE(bh, "call ext4_journal_revoke");
116    err = ext4_journal_revoke(handle, blocknr, bh);
117    if (err)
118        ext4_abort(inode->i_sb, __func__,
119               "error %d when attempting revoke", err);
120    BUFFER_TRACE(bh, "exit");
121    return err;
122}
123
124/*
125 * Work out how many blocks we need to proceed with the next chunk of a
126 * truncate transaction.
127 */
128static unsigned long blocks_for_truncate(struct inode *inode)
129{
130    ext4_lblk_t needed;
131
132    needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
133
134    /* Give ourselves just enough room to cope with inodes in which
135     * i_blocks is corrupt: we've seen disk corruptions in the past
136     * which resulted in random data in an inode which looked enough
137     * like a regular file for ext4 to try to delete it. Things
138     * will go a bit crazy if that happens, but at least we should
139     * try not to panic the whole kernel. */
140    if (needed < 2)
141        needed = 2;
142
143    /* But we need to bound the transaction so we don't overflow the
144     * journal. */
145    if (needed > EXT4_MAX_TRANS_DATA)
146        needed = EXT4_MAX_TRANS_DATA;
147
148    return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
149}
150
151/*
152 * Truncate transactions can be complex and absolutely huge. So we need to
153 * be able to restart the transaction at a conventient checkpoint to make
154 * sure we don't overflow the journal.
155 *
156 * start_transaction gets us a new handle for a truncate transaction,
157 * and extend_transaction tries to extend the existing one a bit. If
158 * extend fails, we need to propagate the failure up and restart the
159 * transaction in the top-level truncate loop. --sct
160 */
161static handle_t *start_transaction(struct inode *inode)
162{
163    handle_t *result;
164
165    result = ext4_journal_start(inode, blocks_for_truncate(inode));
166    if (!IS_ERR(result))
167        return result;
168
169    ext4_std_error(inode->i_sb, PTR_ERR(result));
170    return result;
171}
172
173/*
174 * Try to extend this transaction for the purposes of truncation.
175 *
176 * Returns 0 if we managed to create more room. If we can't create more
177 * room, and the transaction must be restarted we return 1.
178 */
179static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
180{
181    if (!ext4_handle_valid(handle))
182        return 0;
183    if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
184        return 0;
185    if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
186        return 0;
187    return 1;
188}
189
190/*
191 * Restart the transaction associated with *handle. This does a commit,
192 * so before we call here everything must be consistently dirtied against
193 * this transaction.
194 */
195static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
196{
197    BUG_ON(EXT4_JOURNAL(inode) == NULL);
198    jbd_debug(2, "restarting handle %p\n", handle);
199    return ext4_journal_restart(handle, blocks_for_truncate(inode));
200}
201
202/*
203 * Called at the last iput() if i_nlink is zero.
204 */
205void ext4_delete_inode(struct inode *inode)
206{
207    handle_t *handle;
208    int err;
209
210    if (ext4_should_order_data(inode))
211        ext4_begin_ordered_truncate(inode, 0);
212    truncate_inode_pages(&inode->i_data, 0);
213
214    if (is_bad_inode(inode))
215        goto no_delete;
216
217    handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
218    if (IS_ERR(handle)) {
219        ext4_std_error(inode->i_sb, PTR_ERR(handle));
220        /*
221         * If we're going to skip the normal cleanup, we still need to
222         * make sure that the in-core orphan linked list is properly
223         * cleaned up.
224         */
225        ext4_orphan_del(NULL, inode);
226        goto no_delete;
227    }
228
229    if (IS_SYNC(inode))
230        ext4_handle_sync(handle);
231    inode->i_size = 0;
232    err = ext4_mark_inode_dirty(handle, inode);
233    if (err) {
234        ext4_warning(inode->i_sb, __func__,
235                 "couldn't mark inode dirty (err %d)", err);
236        goto stop_handle;
237    }
238    if (inode->i_blocks)
239        ext4_truncate(inode);
240
241    /*
242     * ext4_ext_truncate() doesn't reserve any slop when it
243     * restarts journal transactions; therefore there may not be
244     * enough credits left in the handle to remove the inode from
245     * the orphan list and set the dtime field.
246     */
247    if (!ext4_handle_has_enough_credits(handle, 3)) {
248        err = ext4_journal_extend(handle, 3);
249        if (err > 0)
250            err = ext4_journal_restart(handle, 3);
251        if (err != 0) {
252            ext4_warning(inode->i_sb, __func__,
253                     "couldn't extend journal (err %d)", err);
254        stop_handle:
255            ext4_journal_stop(handle);
256            goto no_delete;
257        }
258    }
259
260    /*
261     * Kill off the orphan record which ext4_truncate created.
262     * AKPM: I think this can be inside the above `if'.
263     * Note that ext4_orphan_del() has to be able to cope with the
264     * deletion of a non-existent orphan - this is because we don't
265     * know if ext4_truncate() actually created an orphan record.
266     * (Well, we could do this if we need to, but heck - it works)
267     */
268    ext4_orphan_del(handle, inode);
269    EXT4_I(inode)->i_dtime = get_seconds();
270
271    /*
272     * One subtle ordering requirement: if anything has gone wrong
273     * (transaction abort, IO errors, whatever), then we can still
274     * do these next steps (the fs will already have been marked as
275     * having errors), but we can't free the inode if the mark_dirty
276     * fails.
277     */
278    if (ext4_mark_inode_dirty(handle, inode))
279        /* If that failed, just do the required in-core inode clear. */
280        clear_inode(inode);
281    else
282        ext4_free_inode(handle, inode);
283    ext4_journal_stop(handle);
284    return;
285no_delete:
286    clear_inode(inode); /* We must guarantee clearing of inode... */
287}
288
289typedef struct {
290    __le32 *p;
291    __le32 key;
292    struct buffer_head *bh;
293} Indirect;
294
295static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
296{
297    p->key = *(p->p = v);
298    p->bh = bh;
299}
300
301/**
302 * ext4_block_to_path - parse the block number into array of offsets
303 * @inode: inode in question (we are only interested in its superblock)
304 * @i_block: block number to be parsed
305 * @offsets: array to store the offsets in
306 * @boundary: set this non-zero if the referred-to block is likely to be
307 * followed (on disk) by an indirect block.
308 *
309 * To store the locations of file's data ext4 uses a data structure common
310 * for UNIX filesystems - tree of pointers anchored in the inode, with
311 * data blocks at leaves and indirect blocks in intermediate nodes.
312 * This function translates the block number into path in that tree -
313 * return value is the path length and @offsets[n] is the offset of
314 * pointer to (n+1)th node in the nth one. If @block is out of range
315 * (negative or too large) warning is printed and zero returned.
316 *
317 * Note: function doesn't find node addresses, so no IO is needed. All
318 * we need to know is the capacity of indirect blocks (taken from the
319 * inode->i_sb).
320 */
321
322/*
323 * Portability note: the last comparison (check that we fit into triple
324 * indirect block) is spelled differently, because otherwise on an
325 * architecture with 32-bit longs and 8Kb pages we might get into trouble
326 * if our filesystem had 8Kb blocks. We might use long long, but that would
327 * kill us on x86. Oh, well, at least the sign propagation does not matter -
328 * i_block would have to be negative in the very beginning, so we would not
329 * get there at all.
330 */
331
332static int ext4_block_to_path(struct inode *inode,
333                  ext4_lblk_t i_block,
334                  ext4_lblk_t offsets[4], int *boundary)
335{
336    int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
337    int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
338    const long direct_blocks = EXT4_NDIR_BLOCKS,
339        indirect_blocks = ptrs,
340        double_blocks = (1 << (ptrs_bits * 2));
341    int n = 0;
342    int final = 0;
343
344    if (i_block < 0) {
345        ext4_warning(inode->i_sb, "ext4_block_to_path", "block < 0");
346    } else if (i_block < direct_blocks) {
347        offsets[n++] = i_block;
348        final = direct_blocks;
349    } else if ((i_block -= direct_blocks) < indirect_blocks) {
350        offsets[n++] = EXT4_IND_BLOCK;
351        offsets[n++] = i_block;
352        final = ptrs;
353    } else if ((i_block -= indirect_blocks) < double_blocks) {
354        offsets[n++] = EXT4_DIND_BLOCK;
355        offsets[n++] = i_block >> ptrs_bits;
356        offsets[n++] = i_block & (ptrs - 1);
357        final = ptrs;
358    } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
359        offsets[n++] = EXT4_TIND_BLOCK;
360        offsets[n++] = i_block >> (ptrs_bits * 2);
361        offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
362        offsets[n++] = i_block & (ptrs - 1);
363        final = ptrs;
364    } else {
365        ext4_warning(inode->i_sb, "ext4_block_to_path",
366                 "block %lu > max in inode %lu",
367                 i_block + direct_blocks +
368                 indirect_blocks + double_blocks, inode->i_ino);
369    }
370    if (boundary)
371        *boundary = final - 1 - (i_block & (ptrs - 1));
372    return n;
373}
374
375static int __ext4_check_blockref(const char *function, struct inode *inode,
376                 __le32 *p, unsigned int max)
377{
378    __le32 *bref = p;
379    unsigned int blk;
380
381    while (bref < p+max) {
382        blk = le32_to_cpu(*bref++);
383        if (blk &&
384            unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
385                            blk, 1))) {
386            ext4_error(inode->i_sb, function,
387                   "invalid block reference %u "
388                   "in inode #%lu", blk, inode->i_ino);
389            return -EIO;
390        }
391    }
392    return 0;
393}
394
395
396#define ext4_check_indirect_blockref(inode, bh) \
397    __ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data, \
398                  EXT4_ADDR_PER_BLOCK((inode)->i_sb))
399
400#define ext4_check_inode_blockref(inode) \
401    __ext4_check_blockref(__func__, inode, EXT4_I(inode)->i_data, \
402                  EXT4_NDIR_BLOCKS)
403
404/**
405 * ext4_get_branch - read the chain of indirect blocks leading to data
406 * @inode: inode in question
407 * @depth: depth of the chain (1 - direct pointer, etc.)
408 * @offsets: offsets of pointers in inode/indirect blocks
409 * @chain: place to store the result
410 * @err: here we store the error value
411 *
412 * Function fills the array of triples <key, p, bh> and returns %NULL
413 * if everything went OK or the pointer to the last filled triple
414 * (incomplete one) otherwise. Upon the return chain[i].key contains
415 * the number of (i+1)-th block in the chain (as it is stored in memory,
416 * i.e. little-endian 32-bit), chain[i].p contains the address of that
417 * number (it points into struct inode for i==0 and into the bh->b_data
418 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
419 * block for i>0 and NULL for i==0. In other words, it holds the block
420 * numbers of the chain, addresses they were taken from (and where we can
421 * verify that chain did not change) and buffer_heads hosting these
422 * numbers.
423 *
424 * Function stops when it stumbles upon zero pointer (absent block)
425 * (pointer to last triple returned, *@err == 0)
426 * or when it gets an IO error reading an indirect block
427 * (ditto, *@err == -EIO)
428 * or when it reads all @depth-1 indirect blocks successfully and finds
429 * the whole chain, all way to the data (returns %NULL, *err == 0).
430 *
431 * Need to be called with
432 * down_read(&EXT4_I(inode)->i_data_sem)
433 */
434static Indirect *ext4_get_branch(struct inode *inode, int depth,
435                 ext4_lblk_t *offsets,
436                 Indirect chain[4], int *err)
437{
438    struct super_block *sb = inode->i_sb;
439    Indirect *p = chain;
440    struct buffer_head *bh;
441
442    *err = 0;
443    /* i_data is not going away, no lock needed */
444    add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
445    if (!p->key)
446        goto no_block;
447    while (--depth) {
448        bh = sb_getblk(sb, le32_to_cpu(p->key));
449        if (unlikely(!bh))
450            goto failure;
451
452        if (!bh_uptodate_or_lock(bh)) {
453            if (bh_submit_read(bh) < 0) {
454                put_bh(bh);
455                goto failure;
456            }
457            /* validate block references */
458            if (ext4_check_indirect_blockref(inode, bh)) {
459                put_bh(bh);
460                goto failure;
461            }
462        }
463
464        add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
465        /* Reader: end */
466        if (!p->key)
467            goto no_block;
468    }
469    return NULL;
470
471failure:
472    *err = -EIO;
473no_block:
474    return p;
475}
476
477/**
478 * ext4_find_near - find a place for allocation with sufficient locality
479 * @inode: owner
480 * @ind: descriptor of indirect block.
481 *
482 * This function returns the preferred place for block allocation.
483 * It is used when heuristic for sequential allocation fails.
484 * Rules are:
485 * + if there is a block to the left of our position - allocate near it.
486 * + if pointer will live in indirect block - allocate near that block.
487 * + if pointer will live in inode - allocate in the same
488 * cylinder group.
489 *
490 * In the latter case we colour the starting block by the callers PID to
491 * prevent it from clashing with concurrent allocations for a different inode
492 * in the same block group. The PID is used here so that functionally related
493 * files will be close-by on-disk.
494 *
495 * Caller must make sure that @ind is valid and will stay that way.
496 */
497static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
498{
499    struct ext4_inode_info *ei = EXT4_I(inode);
500    __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
501    __le32 *p;
502    ext4_fsblk_t bg_start;
503    ext4_fsblk_t last_block;
504    ext4_grpblk_t colour;
505    ext4_group_t block_group;
506    int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
507
508    /* Try to find previous block */
509    for (p = ind->p - 1; p >= start; p--) {
510        if (*p)
511            return le32_to_cpu(*p);
512    }
513
514    /* No such thing, so let's try location of indirect block */
515    if (ind->bh)
516        return ind->bh->b_blocknr;
517
518    /*
519     * It is going to be referred to from the inode itself? OK, just put it
520     * into the same cylinder group then.
521     */
522    block_group = ei->i_block_group;
523    if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
524        block_group &= ~(flex_size-1);
525        if (S_ISREG(inode->i_mode))
526            block_group++;
527    }
528    bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
529    last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
530
531    /*
532     * If we are doing delayed allocation, we don't need take
533     * colour into account.
534     */
535    if (test_opt(inode->i_sb, DELALLOC))
536        return bg_start;
537
538    if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
539        colour = (current->pid % 16) *
540            (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
541    else
542        colour = (current->pid % 16) * ((last_block - bg_start) / 16);
543    return bg_start + colour;
544}
545
546/**
547 * ext4_find_goal - find a preferred place for allocation.
548 * @inode: owner
549 * @block: block we want
550 * @partial: pointer to the last triple within a chain
551 *
552 * Normally this function find the preferred place for block allocation,
553 * returns it.
554 */
555static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
556                   Indirect *partial)
557{
558    /*
559     * XXX need to get goal block from mballoc's data structures
560     */
561
562    return ext4_find_near(inode, partial);
563}
564
565/**
566 * ext4_blks_to_allocate: Look up the block map and count the number
567 * of direct blocks need to be allocated for the given branch.
568 *
569 * @branch: chain of indirect blocks
570 * @k: number of blocks need for indirect blocks
571 * @blks: number of data blocks to be mapped.
572 * @blocks_to_boundary: the offset in the indirect block
573 *
574 * return the total number of blocks to be allocate, including the
575 * direct and indirect blocks.
576 */
577static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
578                 int blocks_to_boundary)
579{
580    unsigned int count = 0;
581
582    /*
583     * Simple case, [t,d]Indirect block(s) has not allocated yet
584     * then it's clear blocks on that path have not allocated
585     */
586    if (k > 0) {
587        /* right now we don't handle cross boundary allocation */
588        if (blks < blocks_to_boundary + 1)
589            count += blks;
590        else
591            count += blocks_to_boundary + 1;
592        return count;
593    }
594
595    count++;
596    while (count < blks && count <= blocks_to_boundary &&
597        le32_to_cpu(*(branch[0].p + count)) == 0) {
598        count++;
599    }
600    return count;
601}
602
603/**
604 * ext4_alloc_blocks: multiple allocate blocks needed for a branch
605 * @indirect_blks: the number of blocks need to allocate for indirect
606 * blocks
607 *
608 * @new_blocks: on return it will store the new block numbers for
609 * the indirect blocks(if needed) and the first direct block,
610 * @blks: on return it will store the total number of allocated
611 * direct blocks
612 */
613static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
614                 ext4_lblk_t iblock, ext4_fsblk_t goal,
615                 int indirect_blks, int blks,
616                 ext4_fsblk_t new_blocks[4], int *err)
617{
618    struct ext4_allocation_request ar;
619    int target, i;
620    unsigned long count = 0, blk_allocated = 0;
621    int index = 0;
622    ext4_fsblk_t current_block = 0;
623    int ret = 0;
624
625    /*
626     * Here we try to allocate the requested multiple blocks at once,
627     * on a best-effort basis.
628     * To build a branch, we should allocate blocks for
629     * the indirect blocks(if not allocated yet), and at least
630     * the first direct block of this branch. That's the
631     * minimum number of blocks need to allocate(required)
632     */
633    /* first we try to allocate the indirect blocks */
634    target = indirect_blks;
635    while (target > 0) {
636        count = target;
637        /* allocating blocks for indirect blocks and direct blocks */
638        current_block = ext4_new_meta_blocks(handle, inode,
639                            goal, &count, err);
640        if (*err)
641            goto failed_out;
642
643        target -= count;
644        /* allocate blocks for indirect blocks */
645        while (index < indirect_blks && count) {
646            new_blocks[index++] = current_block++;
647            count--;
648        }
649        if (count > 0) {
650            /*
651             * save the new block number
652             * for the first direct block
653             */
654            new_blocks[index] = current_block;
655            printk(KERN_INFO "%s returned more blocks than "
656                        "requested\n", __func__);
657            WARN_ON(1);
658            break;
659        }
660    }
661
662    target = blks - count ;
663    blk_allocated = count;
664    if (!target)
665        goto allocated;
666    /* Now allocate data blocks */
667    memset(&ar, 0, sizeof(ar));
668    ar.inode = inode;
669    ar.goal = goal;
670    ar.len = target;
671    ar.logical = iblock;
672    if (S_ISREG(inode->i_mode))
673        /* enable in-core preallocation only for regular files */
674        ar.flags = EXT4_MB_HINT_DATA;
675
676    current_block = ext4_mb_new_blocks(handle, &ar, err);
677
678    if (*err && (target == blks)) {
679        /*
680         * if the allocation failed and we didn't allocate
681         * any blocks before
682         */
683        goto failed_out;
684    }
685    if (!*err) {
686        if (target == blks) {
687            /*
688             * save the new block number
689             * for the first direct block
690             */
691            new_blocks[index] = current_block;
692        }
693        blk_allocated += ar.len;
694    }
695allocated:
696    /* total number of blocks allocated for direct blocks */
697    ret = blk_allocated;
698    *err = 0;
699    return ret;
700failed_out:
701    for (i = 0; i < index; i++)
702        ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
703    return ret;
704}
705
706/**
707 * ext4_alloc_branch - allocate and set up a chain of blocks.
708 * @inode: owner
709 * @indirect_blks: number of allocated indirect blocks
710 * @blks: number of allocated direct blocks
711 * @offsets: offsets (in the blocks) to store the pointers to next.
712 * @branch: place to store the chain in.
713 *
714 * This function allocates blocks, zeroes out all but the last one,
715 * links them into chain and (if we are synchronous) writes them to disk.
716 * In other words, it prepares a branch that can be spliced onto the
717 * inode. It stores the information about that chain in the branch[], in
718 * the same format as ext4_get_branch() would do. We are calling it after
719 * we had read the existing part of chain and partial points to the last
720 * triple of that (one with zero ->key). Upon the exit we have the same
721 * picture as after the successful ext4_get_block(), except that in one
722 * place chain is disconnected - *branch->p is still zero (we did not
723 * set the last link), but branch->key contains the number that should
724 * be placed into *branch->p to fill that gap.
725 *
726 * If allocation fails we free all blocks we've allocated (and forget
727 * their buffer_heads) and return the error value the from failed
728 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
729 * as described above and return 0.
730 */
731static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
732                 ext4_lblk_t iblock, int indirect_blks,
733                 int *blks, ext4_fsblk_t goal,
734                 ext4_lblk_t *offsets, Indirect *branch)
735{
736    int blocksize = inode->i_sb->s_blocksize;
737    int i, n = 0;
738    int err = 0;
739    struct buffer_head *bh;
740    int num;
741    ext4_fsblk_t new_blocks[4];
742    ext4_fsblk_t current_block;
743
744    num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
745                *blks, new_blocks, &err);
746    if (err)
747        return err;
748
749    branch[0].key = cpu_to_le32(new_blocks[0]);
750    /*
751     * metadata blocks and data blocks are allocated.
752     */
753    for (n = 1; n <= indirect_blks; n++) {
754        /*
755         * Get buffer_head for parent block, zero it out
756         * and set the pointer to new one, then send
757         * parent to disk.
758         */
759        bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
760        branch[n].bh = bh;
761        lock_buffer(bh);
762        BUFFER_TRACE(bh, "call get_create_access");
763        err = ext4_journal_get_create_access(handle, bh);
764        if (err) {
765            unlock_buffer(bh);
766            brelse(bh);
767            goto failed;
768        }
769
770        memset(bh->b_data, 0, blocksize);
771        branch[n].p = (__le32 *) bh->b_data + offsets[n];
772        branch[n].key = cpu_to_le32(new_blocks[n]);
773        *branch[n].p = branch[n].key;
774        if (n == indirect_blks) {
775            current_block = new_blocks[n];
776            /*
777             * End of chain, update the last new metablock of
778             * the chain to point to the new allocated
779             * data blocks numbers
780             */
781            for (i = 1; i < num; i++)
782                *(branch[n].p + i) = cpu_to_le32(++current_block);
783        }
784        BUFFER_TRACE(bh, "marking uptodate");
785        set_buffer_uptodate(bh);
786        unlock_buffer(bh);
787
788        BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
789        err = ext4_handle_dirty_metadata(handle, inode, bh);
790        if (err)
791            goto failed;
792    }
793    *blks = num;
794    return err;
795failed:
796    /* Allocation failed, free what we already allocated */
797    for (i = 1; i <= n ; i++) {
798        BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
799        ext4_journal_forget(handle, branch[i].bh);
800    }
801    for (i = 0; i < indirect_blks; i++)
802        ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
803
804    ext4_free_blocks(handle, inode, new_blocks[i], num, 0);
805
806    return err;
807}
808
809/**
810 * ext4_splice_branch - splice the allocated branch onto inode.
811 * @inode: owner
812 * @block: (logical) number of block we are adding
813 * @chain: chain of indirect blocks (with a missing link - see
814 * ext4_alloc_branch)
815 * @where: location of missing link
816 * @num: number of indirect blocks we are adding
817 * @blks: number of direct blocks we are adding
818 *
819 * This function fills the missing link and does all housekeeping needed in
820 * inode (->i_blocks, etc.). In case of success we end up with the full
821 * chain to new block and return 0.
822 */
823static int ext4_splice_branch(handle_t *handle, struct inode *inode,
824                  ext4_lblk_t block, Indirect *where, int num,
825                  int blks)
826{
827    int i;
828    int err = 0;
829    ext4_fsblk_t current_block;
830
831    /*
832     * If we're splicing into a [td]indirect block (as opposed to the
833     * inode) then we need to get write access to the [td]indirect block
834     * before the splice.
835     */
836    if (where->bh) {
837        BUFFER_TRACE(where->bh, "get_write_access");
838        err = ext4_journal_get_write_access(handle, where->bh);
839        if (err)
840            goto err_out;
841    }
842    /* That's it */
843
844    *where->p = where->key;
845
846    /*
847     * Update the host buffer_head or inode to point to more just allocated
848     * direct blocks blocks
849     */
850    if (num == 0 && blks > 1) {
851        current_block = le32_to_cpu(where->key) + 1;
852        for (i = 1; i < blks; i++)
853            *(where->p + i) = cpu_to_le32(current_block++);
854    }
855
856    /* We are done with atomic stuff, now do the rest of housekeeping */
857    /* had we spliced it onto indirect block? */
858    if (where->bh) {
859        /*
860         * If we spliced it onto an indirect block, we haven't
861         * altered the inode. Note however that if it is being spliced
862         * onto an indirect block at the very end of the file (the
863         * file is growing) then we *will* alter the inode to reflect
864         * the new i_size. But that is not done here - it is done in
865         * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
866         */
867        jbd_debug(5, "splicing indirect only\n");
868        BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
869        err = ext4_handle_dirty_metadata(handle, inode, where->bh);
870        if (err)
871            goto err_out;
872    } else {
873        /*
874         * OK, we spliced it into the inode itself on a direct block.
875         */
876        ext4_mark_inode_dirty(handle, inode);
877        jbd_debug(5, "splicing direct\n");
878    }
879    return err;
880
881err_out:
882    for (i = 1; i <= num; i++) {
883        BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
884        ext4_journal_forget(handle, where[i].bh);
885        ext4_free_blocks(handle, inode,
886                    le32_to_cpu(where[i-1].key), 1, 0);
887    }
888    ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks, 0);
889
890    return err;
891}
892
893/*
894 * The ext4_ind_get_blocks() function handles non-extents inodes
895 * (i.e., using the traditional indirect/double-indirect i_blocks
896 * scheme) for ext4_get_blocks().
897 *
898 * Allocation strategy is simple: if we have to allocate something, we will
899 * have to go the whole way to leaf. So let's do it before attaching anything
900 * to tree, set linkage between the newborn blocks, write them if sync is
901 * required, recheck the path, free and repeat if check fails, otherwise
902 * set the last missing link (that will protect us from any truncate-generated
903 * removals - all blocks on the path are immune now) and possibly force the
904 * write on the parent block.
905 * That has a nice additional property: no special recovery from the failed
906 * allocations is needed - we simply release blocks and do not touch anything
907 * reachable from inode.
908 *
909 * `handle' can be NULL if create == 0.
910 *
911 * return > 0, # of blocks mapped or allocated.
912 * return = 0, if plain lookup failed.
913 * return < 0, error case.
914 *
915 * The ext4_ind_get_blocks() function should be called with
916 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
917 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
918 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
919 * blocks.
920 */
921static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
922                   ext4_lblk_t iblock, unsigned int maxblocks,
923                   struct buffer_head *bh_result,
924                   int flags)
925{
926    int err = -EIO;
927    ext4_lblk_t offsets[4];
928    Indirect chain[4];
929    Indirect *partial;
930    ext4_fsblk_t goal;
931    int indirect_blks;
932    int blocks_to_boundary = 0;
933    int depth;
934    int count = 0;
935    ext4_fsblk_t first_block = 0;
936
937    J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
938    J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
939    depth = ext4_block_to_path(inode, iblock, offsets,
940                   &blocks_to_boundary);
941
942    if (depth == 0)
943        goto out;
944
945    partial = ext4_get_branch(inode, depth, offsets, chain, &err);
946
947    /* Simplest case - block found, no allocation needed */
948    if (!partial) {
949        first_block = le32_to_cpu(chain[depth - 1].key);
950        clear_buffer_new(bh_result);
951        count++;
952        /*map more blocks*/
953        while (count < maxblocks && count <= blocks_to_boundary) {
954            ext4_fsblk_t blk;
955
956            blk = le32_to_cpu(*(chain[depth-1].p + count));
957
958            if (blk == first_block + count)
959                count++;
960            else
961                break;
962        }
963        goto got_it;
964    }
965
966    /* Next simple case - plain lookup or failed read of indirect block */
967    if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
968        goto cleanup;
969
970    /*
971     * Okay, we need to do block allocation.
972    */
973    goal = ext4_find_goal(inode, iblock, partial);
974
975    /* the number of blocks need to allocate for [d,t]indirect blocks */
976    indirect_blks = (chain + depth) - partial - 1;
977
978    /*
979     * Next look up the indirect map to count the totoal number of
980     * direct blocks to allocate for this branch.
981     */
982    count = ext4_blks_to_allocate(partial, indirect_blks,
983                    maxblocks, blocks_to_boundary);
984    /*
985     * Block out ext4_truncate while we alter the tree
986     */
987    err = ext4_alloc_branch(handle, inode, iblock, indirect_blks,
988                &count, goal,
989                offsets + (partial - chain), partial);
990
991    /*
992     * The ext4_splice_branch call will free and forget any buffers
993     * on the new chain if there is a failure, but that risks using
994     * up transaction credits, especially for bitmaps where the
995     * credits cannot be returned. Can we handle this somehow? We
996     * may need to return -EAGAIN upwards in the worst case. --sct
997     */
998    if (!err)
999        err = ext4_splice_branch(handle, inode, iblock,
1000                     partial, indirect_blks, count);
1001    else
1002        goto cleanup;
1003
1004    set_buffer_new(bh_result);
1005got_it:
1006    map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
1007    if (count > blocks_to_boundary)
1008        set_buffer_boundary(bh_result);
1009    err = count;
1010    /* Clean up and exit */
1011    partial = chain + depth - 1; /* the whole chain */
1012cleanup:
1013    while (partial > chain) {
1014        BUFFER_TRACE(partial->bh, "call brelse");
1015        brelse(partial->bh);
1016        partial--;
1017    }
1018    BUFFER_TRACE(bh_result, "returned");
1019out:
1020    return err;
1021}
1022
1023qsize_t ext4_get_reserved_space(struct inode *inode)
1024{
1025    unsigned long long total;
1026
1027    spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1028    total = EXT4_I(inode)->i_reserved_data_blocks +
1029        EXT4_I(inode)->i_reserved_meta_blocks;
1030    spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1031
1032    return total;
1033}
1034/*
1035 * Calculate the number of metadata blocks need to reserve
1036 * to allocate @blocks for non extent file based file
1037 */
1038static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
1039{
1040    int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
1041    int ind_blks, dind_blks, tind_blks;
1042
1043    /* number of new indirect blocks needed */
1044    ind_blks = (blocks + icap - 1) / icap;
1045
1046    dind_blks = (ind_blks + icap - 1) / icap;
1047
1048    tind_blks = 1;
1049
1050    return ind_blks + dind_blks + tind_blks;
1051}
1052
1053/*
1054 * Calculate the number of metadata blocks need to reserve
1055 * to allocate given number of blocks
1056 */
1057static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
1058{
1059    if (!blocks)
1060        return 0;
1061
1062    if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
1063        return ext4_ext_calc_metadata_amount(inode, blocks);
1064
1065    return ext4_indirect_calc_metadata_amount(inode, blocks);
1066}
1067
1068static void ext4_da_update_reserve_space(struct inode *inode, int used)
1069{
1070    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1071    int total, mdb, mdb_free;
1072
1073    spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1074    /* recalculate the number of metablocks still need to be reserved */
1075    total = EXT4_I(inode)->i_reserved_data_blocks - used;
1076    mdb = ext4_calc_metadata_amount(inode, total);
1077
1078    /* figure out how many metablocks to release */
1079    BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1080    mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
1081
1082    if (mdb_free) {
1083        /* Account for allocated meta_blocks */
1084        mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
1085
1086        /* update fs dirty blocks counter */
1087        percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
1088        EXT4_I(inode)->i_allocated_meta_blocks = 0;
1089        EXT4_I(inode)->i_reserved_meta_blocks = mdb;
1090    }
1091
1092    /* update per-inode reservations */
1093    BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
1094    EXT4_I(inode)->i_reserved_data_blocks -= used;
1095    spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1096
1097    /*
1098     * free those over-booking quota for metadata blocks
1099     */
1100    if (mdb_free)
1101        vfs_dq_release_reservation_block(inode, mdb_free);
1102
1103    /*
1104     * If we have done all the pending block allocations and if
1105     * there aren't any writers on the inode, we can discard the
1106     * inode's preallocations.
1107     */
1108    if (!total && (atomic_read(&inode->i_writecount) == 0))
1109        ext4_discard_preallocations(inode);
1110}
1111
1112static int check_block_validity(struct inode *inode, sector_t logical,
1113                sector_t phys, int len)
1114{
1115    if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), phys, len)) {
1116        ext4_error(inode->i_sb, "check_block_validity",
1117               "inode #%lu logical block %llu mapped to %llu "
1118               "(size %d)", inode->i_ino,
1119               (unsigned long long) logical,
1120               (unsigned long long) phys, len);
1121        WARN_ON(1);
1122        return -EIO;
1123    }
1124    return 0;
1125}
1126
1127/*
1128 * The ext4_get_blocks() function tries to look up the requested blocks,
1129 * and returns if the blocks are already mapped.
1130 *
1131 * Otherwise it takes the write lock of the i_data_sem and allocate blocks
1132 * and store the allocated blocks in the result buffer head and mark it
1133 * mapped.
1134 *
1135 * If file type is extents based, it will call ext4_ext_get_blocks(),
1136 * Otherwise, call with ext4_ind_get_blocks() to handle indirect mapping
1137 * based files
1138 *
1139 * On success, it returns the number of blocks being mapped or allocate.
1140 * if create==0 and the blocks are pre-allocated and uninitialized block,
1141 * the result buffer head is unmapped. If the create ==1, it will make sure
1142 * the buffer head is mapped.
1143 *
1144 * It returns 0 if plain look up failed (blocks have not been allocated), in
1145 * that casem, buffer head is unmapped
1146 *
1147 * It returns the error in case of allocation failure.
1148 */
1149int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
1150            unsigned int max_blocks, struct buffer_head *bh,
1151            int flags)
1152{
1153    int retval;
1154
1155    clear_buffer_mapped(bh);
1156    clear_buffer_unwritten(bh);
1157
1158    /*
1159     * Try to see if we can get the block without requesting a new
1160     * file system block.
1161     */
1162    down_read((&EXT4_I(inode)->i_data_sem));
1163    if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
1164        retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
1165                bh, 0);
1166    } else {
1167        retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
1168                         bh, 0);
1169    }
1170    up_read((&EXT4_I(inode)->i_data_sem));
1171
1172    if (retval > 0 && buffer_mapped(bh)) {
1173        int ret = check_block_validity(inode, block,
1174                           bh->b_blocknr, retval);
1175        if (ret != 0)
1176            return ret;
1177    }
1178
1179    /* If it is only a block(s) look up */
1180    if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
1181        return retval;
1182
1183    /*
1184     * Returns if the blocks have already allocated
1185     *
1186     * Note that if blocks have been preallocated
1187     * ext4_ext_get_block() returns th create = 0
1188     * with buffer head unmapped.
1189     */
1190    if (retval > 0 && buffer_mapped(bh))
1191        return retval;
1192
1193    /*
1194     * When we call get_blocks without the create flag, the
1195     * BH_Unwritten flag could have gotten set if the blocks
1196     * requested were part of a uninitialized extent. We need to
1197     * clear this flag now that we are committed to convert all or
1198     * part of the uninitialized extent to be an initialized
1199     * extent. This is because we need to avoid the combination
1200     * of BH_Unwritten and BH_Mapped flags being simultaneously
1201     * set on the buffer_head.
1202     */
1203    clear_buffer_unwritten(bh);
1204
1205    /*
1206     * New blocks allocate and/or writing to uninitialized extent
1207     * will possibly result in updating i_data, so we take
1208     * the write lock of i_data_sem, and call get_blocks()
1209     * with create == 1 flag.
1210     */
1211    down_write((&EXT4_I(inode)->i_data_sem));
1212
1213    /*
1214     * if the caller is from delayed allocation writeout path
1215     * we have already reserved fs blocks for allocation
1216     * let the underlying get_block() function know to
1217     * avoid double accounting
1218     */
1219    if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1220        EXT4_I(inode)->i_delalloc_reserved_flag = 1;
1221    /*
1222     * We need to check for EXT4 here because migrate
1223     * could have changed the inode type in between
1224     */
1225    if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
1226        retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
1227                          bh, flags);
1228    } else {
1229        retval = ext4_ind_get_blocks(handle, inode, block,
1230                         max_blocks, bh, flags);
1231
1232        if (retval > 0 && buffer_new(bh)) {
1233            /*
1234             * We allocated new blocks which will result in
1235             * i_data's format changing. Force the migrate
1236             * to fail by clearing migrate flags
1237             */
1238            EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
1239                            ~EXT4_EXT_MIGRATE;
1240        }
1241    }
1242
1243    if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1244        EXT4_I(inode)->i_delalloc_reserved_flag = 0;
1245
1246    /*
1247     * Update reserved blocks/metadata blocks after successful
1248     * block allocation which had been deferred till now.
1249     */
1250    if ((retval > 0) && (flags & EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE))
1251        ext4_da_update_reserve_space(inode, retval);
1252
1253    up_write((&EXT4_I(inode)->i_data_sem));
1254    if (retval > 0 && buffer_mapped(bh)) {
1255        int ret = check_block_validity(inode, block,
1256                           bh->b_blocknr, retval);
1257        if (ret != 0)
1258            return ret;
1259    }
1260    return retval;
1261}
1262
1263/* Maximum number of blocks we map for direct IO at once. */
1264#define DIO_MAX_BLOCKS 4096
1265
1266int ext4_get_block(struct inode *inode, sector_t iblock,
1267           struct buffer_head *bh_result, int create)
1268{
1269    handle_t *handle = ext4_journal_current_handle();
1270    int ret = 0, started = 0;
1271    unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
1272    int dio_credits;
1273
1274    if (create && !handle) {
1275        /* Direct IO write... */
1276        if (max_blocks > DIO_MAX_BLOCKS)
1277            max_blocks = DIO_MAX_BLOCKS;
1278        dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
1279        handle = ext4_journal_start(inode, dio_credits);
1280        if (IS_ERR(handle)) {
1281            ret = PTR_ERR(handle);
1282            goto out;
1283        }
1284        started = 1;
1285    }
1286
1287    ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
1288                  create ? EXT4_GET_BLOCKS_CREATE : 0);
1289    if (ret > 0) {
1290        bh_result->b_size = (ret << inode->i_blkbits);
1291        ret = 0;
1292    }
1293    if (started)
1294        ext4_journal_stop(handle);
1295out:
1296    return ret;
1297}
1298
1299/*
1300 * `handle' can be NULL if create is zero
1301 */
1302struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1303                ext4_lblk_t block, int create, int *errp)
1304{
1305    struct buffer_head dummy;
1306    int fatal = 0, err;
1307    int flags = 0;
1308
1309    J_ASSERT(handle != NULL || create == 0);
1310
1311    dummy.b_state = 0;
1312    dummy.b_blocknr = -1000;
1313    buffer_trace_init(&dummy.b_history);
1314    if (create)
1315        flags |= EXT4_GET_BLOCKS_CREATE;
1316    err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
1317    /*
1318     * ext4_get_blocks() returns number of blocks mapped. 0 in
1319     * case of a HOLE.
1320     */
1321    if (err > 0) {
1322        if (err > 1)
1323            WARN_ON(1);
1324        err = 0;
1325    }
1326    *errp = err;
1327    if (!err && buffer_mapped(&dummy)) {
1328        struct buffer_head *bh;
1329        bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
1330        if (!bh) {
1331            *errp = -EIO;
1332            goto err;
1333        }
1334        if (buffer_new(&dummy)) {
1335            J_ASSERT(create != 0);
1336            J_ASSERT(handle != NULL);
1337
1338            /*
1339             * Now that we do not always journal data, we should
1340             * keep in mind whether this should always journal the
1341             * new buffer as metadata. For now, regular file
1342             * writes use ext4_get_block instead, so it's not a
1343             * problem.
1344             */
1345            lock_buffer(bh);
1346            BUFFER_TRACE(bh, "call get_create_access");
1347            fatal = ext4_journal_get_create_access(handle, bh);
1348            if (!fatal && !buffer_uptodate(bh)) {
1349                memset(bh->b_data, 0, inode->i_sb->s_blocksize);
1350                set_buffer_uptodate(bh);
1351            }
1352            unlock_buffer(bh);
1353            BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1354            err = ext4_handle_dirty_metadata(handle, inode, bh);
1355            if (!fatal)
1356                fatal = err;
1357        } else {
1358            BUFFER_TRACE(bh, "not a new buffer");
1359        }
1360        if (fatal) {
1361            *errp = fatal;
1362            brelse(bh);
1363            bh = NULL;
1364        }
1365        return bh;
1366    }
1367err:
1368    return NULL;
1369}
1370
1371struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1372                   ext4_lblk_t block, int create, int *err)
1373{
1374    struct buffer_head *bh;
1375
1376    bh = ext4_getblk(handle, inode, block, create, err);
1377    if (!bh)
1378        return bh;
1379    if (buffer_uptodate(bh))
1380        return bh;
1381    ll_rw_block(READ_META, 1, &bh);
1382    wait_on_buffer(bh);
1383    if (buffer_uptodate(bh))
1384        return bh;
1385    put_bh(bh);
1386    *err = -EIO;
1387    return NULL;
1388}
1389
1390static int walk_page_buffers(handle_t *handle,
1391                 struct buffer_head *head,
1392                 unsigned from,
1393                 unsigned to,
1394                 int *partial,
1395                 int (*fn)(handle_t *handle,
1396                       struct buffer_head *bh))
1397{
1398    struct buffer_head *bh;
1399    unsigned block_start, block_end;
1400    unsigned blocksize = head->b_size;
1401    int err, ret = 0;
1402    struct buffer_head *next;
1403
1404    for (bh = head, block_start = 0;
1405         ret == 0 && (bh != head || !block_start);
1406         block_start = block_end, bh = next) {
1407        next = bh->b_this_page;
1408        block_end = block_start + blocksize;
1409        if (block_end <= from || block_start >= to) {
1410            if (partial && !buffer_uptodate(bh))
1411                *partial = 1;
1412            continue;
1413        }
1414        err = (*fn)(handle, bh);
1415        if (!ret)
1416            ret = err;
1417    }
1418    return ret;
1419}
1420
1421/*
1422 * To preserve ordering, it is essential that the hole instantiation and
1423 * the data write be encapsulated in a single transaction. We cannot
1424 * close off a transaction and start a new one between the ext4_get_block()
1425 * and the commit_write(). So doing the jbd2_journal_start at the start of
1426 * prepare_write() is the right place.
1427 *
1428 * Also, this function can nest inside ext4_writepage() ->
1429 * block_write_full_page(). In that case, we *know* that ext4_writepage()
1430 * has generated enough buffer credits to do the whole page. So we won't
1431 * block on the journal in that case, which is good, because the caller may
1432 * be PF_MEMALLOC.
1433 *
1434 * By accident, ext4 can be reentered when a transaction is open via
1435 * quota file writes. If we were to commit the transaction while thus
1436 * reentered, there can be a deadlock - we would be holding a quota
1437 * lock, and the commit would never complete if another thread had a
1438 * transaction open and was blocking on the quota lock - a ranking
1439 * violation.
1440 *
1441 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1442 * will _not_ run commit under these circumstances because handle->h_ref
1443 * is elevated. We'll still have enough credits for the tiny quotafile
1444 * write.
1445 */
1446static int do_journal_get_write_access(handle_t *handle,
1447                       struct buffer_head *bh)
1448{
1449    if (!buffer_mapped(bh) || buffer_freed(bh))
1450        return 0;
1451    return ext4_journal_get_write_access(handle, bh);
1452}
1453
1454static int ext4_write_begin(struct file *file, struct address_space *mapping,
1455                loff_t pos, unsigned len, unsigned flags,
1456                struct page **pagep, void **fsdata)
1457{
1458    struct inode *inode = mapping->host;
1459    int ret, needed_blocks;
1460    handle_t *handle;
1461    int retries = 0;
1462    struct page *page;
1463    pgoff_t index;
1464    unsigned from, to;
1465
1466    trace_ext4_write_begin(inode, pos, len, flags);
1467    /*
1468     * Reserve one block more for addition to orphan list in case
1469     * we allocate blocks but write fails for some reason
1470     */
1471    needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1472    index = pos >> PAGE_CACHE_SHIFT;
1473    from = pos & (PAGE_CACHE_SIZE - 1);
1474    to = from + len;
1475
1476retry:
1477    handle = ext4_journal_start(inode, needed_blocks);
1478    if (IS_ERR(handle)) {
1479        ret = PTR_ERR(handle);
1480        goto out;
1481    }
1482
1483    /* We cannot recurse into the filesystem as the transaction is already
1484     * started */
1485    flags |= AOP_FLAG_NOFS;
1486
1487    page = grab_cache_page_write_begin(mapping, index, flags);
1488    if (!page) {
1489        ext4_journal_stop(handle);
1490        ret = -ENOMEM;
1491        goto out;
1492    }
1493    *pagep = page;
1494
1495    ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
1496                ext4_get_block);
1497
1498    if (!ret && ext4_should_journal_data(inode)) {
1499        ret = walk_page_buffers(handle, page_buffers(page),
1500                from, to, NULL, do_journal_get_write_access);
1501    }
1502
1503    if (ret) {
1504        unlock_page(page);
1505        page_cache_release(page);
1506        /*
1507         * block_write_begin may have instantiated a few blocks
1508         * outside i_size. Trim these off again. Don't need
1509         * i_size_read because we hold i_mutex.
1510         *
1511         * Add inode to orphan list in case we crash before
1512         * truncate finishes
1513         */
1514        if (pos + len > inode->i_size && ext4_can_truncate(inode))
1515            ext4_orphan_add(handle, inode);
1516
1517        ext4_journal_stop(handle);
1518        if (pos + len > inode->i_size) {
1519            ext4_truncate(inode);
1520            /*
1521             * If truncate failed early the inode might
1522             * still be on the orphan list; we need to
1523             * make sure the inode is removed from the
1524             * orphan list in that case.
1525             */
1526            if (inode->i_nlink)
1527                ext4_orphan_del(NULL, inode);
1528        }
1529    }
1530
1531    if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1532        goto retry;
1533out:
1534    return ret;
1535}
1536
1537/* For write_end() in data=journal mode */
1538static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1539{
1540    if (!buffer_mapped(bh) || buffer_freed(bh))
1541        return 0;
1542    set_buffer_uptodate(bh);
1543    return ext4_handle_dirty_metadata(handle, NULL, bh);
1544}
1545
1546static int ext4_generic_write_end(struct file *file,
1547                  struct address_space *mapping,
1548                  loff_t pos, unsigned len, unsigned copied,
1549                  struct page *page, void *fsdata)
1550{
1551    int i_size_changed = 0;
1552    struct inode *inode = mapping->host;
1553    handle_t *handle = ext4_journal_current_handle();
1554
1555    copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1556
1557    /*
1558     * No need to use i_size_read() here, the i_size
1559     * cannot change under us because we hold i_mutex.
1560     *
1561     * But it's important to update i_size while still holding page lock:
1562     * page writeout could otherwise come in and zero beyond i_size.
1563     */
1564    if (pos + copied > inode->i_size) {
1565        i_size_write(inode, pos + copied);
1566        i_size_changed = 1;
1567    }
1568
1569    if (pos + copied > EXT4_I(inode)->i_disksize) {
1570        /* We need to mark inode dirty even if
1571         * new_i_size is less that inode->i_size
1572         * bu greater than i_disksize.(hint delalloc)
1573         */
1574        ext4_update_i_disksize(inode, (pos + copied));
1575        i_size_changed = 1;
1576    }
1577    unlock_page(page);
1578    page_cache_release(page);
1579
1580    /*
1581     * Don't mark the inode dirty under page lock. First, it unnecessarily
1582     * makes the holding time of page lock longer. Second, it forces lock
1583     * ordering of page lock and transaction start for journaling
1584     * filesystems.
1585     */
1586    if (i_size_changed)
1587        ext4_mark_inode_dirty(handle, inode);
1588
1589    return copied;
1590}
1591
1592/*
1593 * We need to pick up the new inode size which generic_commit_write gave us
1594 * `file' can be NULL - eg, when called from page_symlink().
1595 *
1596 * ext4 never places buffers on inode->i_mapping->private_list. metadata
1597 * buffers are managed internally.
1598 */
1599static int ext4_ordered_write_end(struct file *file,
1600                  struct address_space *mapping,
1601                  loff_t pos, unsigned len, unsigned copied,
1602                  struct page *page, void *fsdata)
1603{
1604    handle_t *handle = ext4_journal_current_handle();
1605    struct inode *inode = mapping->host;
1606    int ret = 0, ret2;
1607
1608    trace_ext4_ordered_write_end(inode, pos, len, copied);
1609    ret = ext4_jbd2_file_inode(handle, inode);
1610
1611    if (ret == 0) {
1612        ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1613                            page, fsdata);
1614        copied = ret2;
1615        if (pos + len > inode->i_size && ext4_can_truncate(inode))
1616            /* if we have allocated more blocks and copied
1617             * less. We will have blocks allocated outside
1618             * inode->i_size. So truncate them
1619             */
1620            ext4_orphan_add(handle, inode);
1621        if (ret2 < 0)
1622            ret = ret2;
1623    }
1624    ret2 = ext4_journal_stop(handle);
1625    if (!ret)
1626        ret = ret2;
1627
1628    if (pos + len > inode->i_size) {
1629        ext4_truncate(inode);
1630        /*
1631         * If truncate failed early the inode might still be
1632         * on the orphan list; we need to make sure the inode
1633         * is removed from the orphan list in that case.
1634         */
1635        if (inode->i_nlink)
1636            ext4_orphan_del(NULL, inode);
1637    }
1638
1639
1640    return ret ? ret : copied;
1641}
1642
1643static int ext4_writeback_write_end(struct file *file,
1644                    struct address_space *mapping,
1645                    loff_t pos, unsigned len, unsigned copied,
1646                    struct page *page, void *fsdata)
1647{
1648    handle_t *handle = ext4_journal_current_handle();
1649    struct inode *inode = mapping->host;
1650    int ret = 0, ret2;
1651
1652    trace_ext4_writeback_write_end(inode, pos, len, copied);
1653    ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1654                            page, fsdata);
1655    copied = ret2;
1656    if (pos + len > inode->i_size && ext4_can_truncate(inode))
1657        /* if we have allocated more blocks and copied
1658         * less. We will have blocks allocated outside
1659         * inode->i_size. So truncate them
1660         */
1661        ext4_orphan_add(handle, inode);
1662
1663    if (ret2 < 0)
1664        ret = ret2;
1665
1666    ret2 = ext4_journal_stop(handle);
1667    if (!ret)
1668        ret = ret2;
1669
1670    if (pos + len > inode->i_size) {
1671        ext4_truncate(inode);
1672        /*
1673         * If truncate failed early the inode might still be
1674         * on the orphan list; we need to make sure the inode
1675         * is removed from the orphan list in that case.
1676         */
1677        if (inode->i_nlink)
1678            ext4_orphan_del(NULL, inode);
1679    }
1680
1681    return ret ? ret : copied;
1682}
1683
1684static int ext4_journalled_write_end(struct file *file,
1685                     struct address_space *mapping,
1686                     loff_t pos, unsigned len, unsigned copied,
1687                     struct page *page, void *fsdata)
1688{
1689    handle_t *handle = ext4_journal_current_handle();
1690    struct inode *inode = mapping->host;
1691    int ret = 0, ret2;
1692    int partial = 0;
1693    unsigned from, to;
1694    loff_t new_i_size;
1695
1696    trace_ext4_journalled_write_end(inode, pos, len, copied);
1697    from = pos & (PAGE_CACHE_SIZE - 1);
1698    to = from + len;
1699
1700    if (copied < len) {
1701        if (!PageUptodate(page))
1702            copied = 0;
1703        page_zero_new_buffers(page, from+copied, to);
1704    }
1705
1706    ret = walk_page_buffers(handle, page_buffers(page), from,
1707                to, &partial, write_end_fn);
1708    if (!partial)
1709        SetPageUptodate(page);
1710    new_i_size = pos + copied;
1711    if (new_i_size > inode->i_size)
1712        i_size_write(inode, pos+copied);
1713    EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1714    if (new_i_size > EXT4_I(inode)->i_disksize) {
1715        ext4_update_i_disksize(inode, new_i_size);
1716        ret2 = ext4_mark_inode_dirty(handle, inode);
1717        if (!ret)
1718            ret = ret2;
1719    }
1720
1721    unlock_page(page);
1722    page_cache_release(page);
1723    if (pos + len > inode->i_size && ext4_can_truncate(inode))
1724        /* if we have allocated more blocks and copied
1725         * less. We will have blocks allocated outside
1726         * inode->i_size. So truncate them
1727         */
1728        ext4_orphan_add(handle, inode);
1729
1730    ret2 = ext4_journal_stop(handle);
1731    if (!ret)
1732        ret = ret2;
1733    if (pos + len > inode->i_size) {
1734        ext4_truncate(inode);
1735        /*
1736         * If truncate failed early the inode might still be
1737         * on the orphan list; we need to make sure the inode
1738         * is removed from the orphan list in that case.
1739         */
1740        if (inode->i_nlink)
1741            ext4_orphan_del(NULL, inode);
1742    }
1743
1744    return ret ? ret : copied;
1745}
1746
1747static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
1748{
1749    int retries = 0;
1750    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1751    unsigned long md_needed, mdblocks, total = 0;
1752
1753    /*
1754     * recalculate the amount of metadata blocks to reserve
1755     * in order to allocate nrblocks
1756     * worse case is one extent per block
1757     */
1758repeat:
1759    spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1760    total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
1761    mdblocks = ext4_calc_metadata_amount(inode, total);
1762    BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks);
1763
1764    md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
1765    total = md_needed + nrblocks;
1766
1767    /*
1768     * Make quota reservation here to prevent quota overflow
1769     * later. Real quota accounting is done at pages writeout
1770     * time.
1771     */
1772    if (vfs_dq_reserve_block(inode, total)) {
1773        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1774        return -EDQUOT;
1775    }
1776
1777    if (ext4_claim_free_blocks(sbi, total)) {
1778        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1779        if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1780            yield();
1781            goto repeat;
1782        }
1783        vfs_dq_release_reservation_block(inode, total);
1784        return -ENOSPC;
1785    }
1786    EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
1787    EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;
1788
1789    spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1790    return 0; /* success */
1791}
1792
1793static void ext4_da_release_space(struct inode *inode, int to_free)
1794{
1795    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1796    int total, mdb, mdb_free, release;
1797
1798    if (!to_free)
1799        return; /* Nothing to release, exit */
1800
1801    spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1802
1803    if (!EXT4_I(inode)->i_reserved_data_blocks) {
1804        /*
1805         * if there is no reserved blocks, but we try to free some
1806         * then the counter is messed up somewhere.
1807         * but since this function is called from invalidate
1808         * page, it's harmless to return without any action
1809         */
1810        printk(KERN_INFO "ext4 delalloc try to release %d reserved "
1811                "blocks for inode %lu, but there is no reserved "
1812                "data blocks\n", to_free, inode->i_ino);
1813        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1814        return;
1815    }
1816
1817    /* recalculate the number of metablocks still need to be reserved */
1818    total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
1819    mdb = ext4_calc_metadata_amount(inode, total);
1820
1821    /* figure out how many metablocks to release */
1822    BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1823    mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
1824
1825    release = to_free + mdb_free;
1826
1827    /* update fs dirty blocks counter for truncate case */
1828    percpu_counter_sub(&sbi->s_dirtyblocks_counter, release);
1829
1830    /* update per-inode reservations */
1831    BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
1832    EXT4_I(inode)->i_reserved_data_blocks -= to_free;
1833
1834    BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
1835    EXT4_I(inode)->i_reserved_meta_blocks = mdb;
1836    spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1837
1838    vfs_dq_release_reservation_block(inode, release);
1839}
1840
1841static void ext4_da_page_release_reservation(struct page *page,
1842                         unsigned long offset)
1843{
1844    int to_release = 0;
1845    struct buffer_head *head, *bh;
1846    unsigned int curr_off = 0;
1847
1848    head = page_buffers(page);
1849    bh = head;
1850    do {
1851        unsigned int next_off = curr_off + bh->b_size;
1852
1853        if ((offset <= curr_off) && (buffer_delay(bh))) {
1854            to_release++;
1855            clear_buffer_delay(bh);
1856        }
1857        curr_off = next_off;
1858    } while ((bh = bh->b_this_page) != head);
1859    ext4_da_release_space(page->mapping->host, to_release);
1860}
1861
1862/*
1863 * Delayed allocation stuff
1864 */
1865
1866struct mpage_da_data {
1867    struct inode *inode;
1868    sector_t b_blocknr; /* start block number of extent */
1869    size_t b_size; /* size of extent */
1870    unsigned long b_state; /* state of the extent */
1871    unsigned long first_page, next_page; /* extent of pages */
1872    struct writeback_control *wbc;
1873    int io_done;
1874    int pages_written;
1875    int retval;
1876};
1877
1878/*
1879 * mpage_da_submit_io - walks through extent of pages and try to write
1880 * them with writepage() call back
1881 *
1882 * @mpd->inode: inode
1883 * @mpd->first_page: first page of the extent
1884 * @mpd->next_page: page after the last page of the extent
1885 *
1886 * By the time mpage_da_submit_io() is called we expect all blocks
1887 * to be allocated. this may be wrong if allocation failed.
1888 *
1889 * As pages are already locked by write_cache_pages(), we can't use it
1890 */
1891static int mpage_da_submit_io(struct mpage_da_data *mpd)
1892{
1893    long pages_skipped;
1894    struct pagevec pvec;
1895    unsigned long index, end;
1896    int ret = 0, err, nr_pages, i;
1897    struct inode *inode = mpd->inode;
1898    struct address_space *mapping = inode->i_mapping;
1899
1900    BUG_ON(mpd->next_page <= mpd->first_page);
1901    /*
1902     * We need to start from the first_page to the next_page - 1
1903     * to make sure we also write the mapped dirty buffer_heads.
1904     * If we look at mpd->b_blocknr we would only be looking
1905     * at the currently mapped buffer_heads.
1906     */
1907    index = mpd->first_page;
1908    end = mpd->next_page - 1;
1909
1910    pagevec_init(&pvec, 0);
1911    while (index <= end) {
1912        nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1913        if (nr_pages == 0)
1914            break;
1915        for (i = 0; i < nr_pages; i++) {
1916            struct page *page = pvec.pages[i];
1917
1918            index = page->index;
1919            if (index > end)
1920                break;
1921            index++;
1922
1923            BUG_ON(!PageLocked(page));
1924            BUG_ON(PageWriteback(page));
1925
1926            pages_skipped = mpd->wbc->pages_skipped;
1927            err = mapping->a_ops->writepage(page, mpd->wbc);
1928            if (!err && (pages_skipped == mpd->wbc->pages_skipped))
1929                /*
1930                 * have successfully written the page
1931                 * without skipping the same
1932                 */
1933                mpd->pages_written++;
1934            /*
1935             * In error case, we have to continue because
1936             * remaining pages are still locked
1937             * XXX: unlock and re-dirty them?
1938             */
1939            if (ret == 0)
1940                ret = err;
1941        }
1942        pagevec_release(&pvec);
1943    }
1944    return ret;
1945}
1946
1947/*
1948 * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
1949 *
1950 * @mpd->inode - inode to walk through
1951 * @exbh->b_blocknr - first block on a disk
1952 * @exbh->b_size - amount of space in bytes
1953 * @logical - first logical block to start assignment with
1954 *
1955 * the function goes through all passed space and put actual disk
1956 * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten
1957 */
1958static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
1959                 struct buffer_head *exbh)
1960{
1961    struct inode *inode = mpd->inode;
1962    struct address_space *mapping = inode->i_mapping;
1963    int blocks = exbh->b_size >> inode->i_blkbits;
1964    sector_t pblock = exbh->b_blocknr, cur_logical;
1965    struct buffer_head *head, *bh;
1966    pgoff_t index, end;
1967    struct pagevec pvec;
1968    int nr_pages, i;
1969
1970    index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
1971    end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
1972    cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1973
1974    pagevec_init(&pvec, 0);
1975
1976    while (index <= end) {
1977        /* XXX: optimize tail */
1978        nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1979        if (nr_pages == 0)
1980            break;
1981        for (i = 0; i < nr_pages; i++) {
1982            struct page *page = pvec.pages[i];
1983
1984            index = page->index;
1985            if (index > end)
1986                break;
1987            index++;
1988
1989            BUG_ON(!PageLocked(page));
1990            BUG_ON(PageWriteback(page));
1991            BUG_ON(!page_has_buffers(page));
1992
1993            bh = page_buffers(page);
1994            head = bh;
1995
1996            /* skip blocks out of the range */
1997            do {
1998                if (cur_logical >= logical)
1999                    break;
2000                cur_logical++;
2001            } while ((bh = bh->b_this_page) != head);
2002
2003            do {
2004                if (cur_logical >= logical + blocks)
2005                    break;
2006
2007                if (buffer_delay(bh) ||
2008                        buffer_unwritten(bh)) {
2009
2010                    BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
2011
2012                    if (buffer_delay(bh)) {
2013                        clear_buffer_delay(bh);
2014                        bh->b_blocknr = pblock;
2015                    } else {
2016                        /*
2017                         * unwritten already should have
2018                         * blocknr assigned. Verify that
2019                         */
2020                        clear_buffer_unwritten(bh);
2021                        BUG_ON(bh->b_blocknr != pblock);
2022                    }
2023
2024                } else if (buffer_mapped(bh))
2025                    BUG_ON(bh->b_blocknr != pblock);
2026
2027                cur_logical++;
2028                pblock++;
2029            } while ((bh = bh->b_this_page) != head);
2030        }
2031        pagevec_release(&pvec);
2032    }
2033}
2034
2035
2036/*
2037 * __unmap_underlying_blocks - just a helper function to unmap
2038 * set of blocks described by @bh
2039 */
2040static inline void __unmap_underlying_blocks(struct inode *inode,
2041                         struct buffer_head *bh)
2042{
2043    struct block_device *bdev = inode->i_sb->s_bdev;
2044    int blocks, i;
2045
2046    blocks = bh->b_size >> inode->i_blkbits;
2047    for (i = 0; i < blocks; i++)
2048        unmap_underlying_metadata(bdev, bh->b_blocknr + i);
2049}
2050
2051static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
2052                    sector_t logical, long blk_cnt)
2053{
2054    int nr_pages, i;
2055    pgoff_t index, end;
2056    struct pagevec pvec;
2057    struct inode *inode = mpd->inode;
2058    struct address_space *mapping = inode->i_mapping;
2059
2060    index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2061    end = (logical + blk_cnt - 1) >>
2062                (PAGE_CACHE_SHIFT - inode->i_blkbits);
2063    while (index <= end) {
2064        nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2065        if (nr_pages == 0)
2066            break;
2067        for (i = 0; i < nr_pages; i++) {
2068            struct page *page = pvec.pages[i];
2069            index = page->index;
2070            if (index > end)
2071                break;
2072            index++;
2073
2074            BUG_ON(!PageLocked(page));
2075            BUG_ON(PageWriteback(page));
2076            block_invalidatepage(page, 0);
2077            ClearPageUptodate(page);
2078            unlock_page(page);
2079        }
2080    }
2081    return;
2082}
2083
2084static void ext4_print_free_blocks(struct inode *inode)
2085{
2086    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2087    printk(KERN_EMERG "Total free blocks count %lld\n",
2088            ext4_count_free_blocks(inode->i_sb));
2089    printk(KERN_EMERG "Free/Dirty block details\n");
2090    printk(KERN_EMERG "free_blocks=%lld\n",
2091            (long long)percpu_counter_sum(&sbi->s_freeblocks_counter));
2092    printk(KERN_EMERG "dirty_blocks=%lld\n",
2093            (long long)percpu_counter_sum(&sbi->s_dirtyblocks_counter));
2094    printk(KERN_EMERG "Block reservation details\n");
2095    printk(KERN_EMERG "i_reserved_data_blocks=%u\n",
2096            EXT4_I(inode)->i_reserved_data_blocks);
2097    printk(KERN_EMERG "i_reserved_meta_blocks=%u\n",
2098            EXT4_I(inode)->i_reserved_meta_blocks);
2099    return;
2100}
2101
2102/*
2103 * mpage_da_map_blocks - go through given space
2104 *
2105 * @mpd - bh describing space
2106 *
2107 * The function skips space we know is already mapped to disk blocks.
2108 *
2109 */
2110static int mpage_da_map_blocks(struct mpage_da_data *mpd)
2111{
2112    int err, blks, get_blocks_flags;
2113    struct buffer_head new;
2114    sector_t next = mpd->b_blocknr;
2115    unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
2116    loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
2117    handle_t *handle = NULL;
2118
2119    /*
2120     * We consider only non-mapped and non-allocated blocks
2121     */
2122    if ((mpd->b_state & (1 << BH_Mapped)) &&
2123        !(mpd->b_state & (1 << BH_Delay)) &&
2124        !(mpd->b_state & (1 << BH_Unwritten)))
2125        return 0;
2126
2127    /*
2128     * If we didn't accumulate anything to write simply return
2129     */
2130    if (!mpd->b_size)
2131        return 0;
2132
2133    handle = ext4_journal_current_handle();
2134    BUG_ON(!handle);
2135
2136    /*
2137     * Call ext4_get_blocks() to allocate any delayed allocation
2138     * blocks, or to convert an uninitialized extent to be
2139     * initialized (in the case where we have written into
2140     * one or more preallocated blocks).
2141     *
2142     * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
2143     * indicate that we are on the delayed allocation path. This
2144     * affects functions in many different parts of the allocation
2145     * call path. This flag exists primarily because we don't
2146     * want to change *many* call functions, so ext4_get_blocks()
2147     * will set the magic i_delalloc_reserved_flag once the
2148     * inode's allocation semaphore is taken.
2149     *
2150     * If the blocks in questions were delalloc blocks, set
2151     * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
2152     * variables are updated after the blocks have been allocated.
2153     */
2154    new.b_state = 0;
2155    get_blocks_flags = (EXT4_GET_BLOCKS_CREATE |
2156                EXT4_GET_BLOCKS_DELALLOC_RESERVE);
2157    if (mpd->b_state & (1 << BH_Delay))
2158        get_blocks_flags |= EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE;
2159    blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,
2160                   &new, get_blocks_flags);
2161    if (blks < 0) {
2162        err = blks;
2163        /*
2164         * If get block returns with error we simply
2165         * return. Later writepage will redirty the page and
2166         * writepages will find the dirty page again
2167         */
2168        if (err == -EAGAIN)
2169            return 0;
2170
2171        if (err == -ENOSPC &&
2172            ext4_count_free_blocks(mpd->inode->i_sb)) {
2173            mpd->retval = err;
2174            return 0;
2175        }
2176
2177        /*
2178         * get block failure will cause us to loop in
2179         * writepages, because a_ops->writepage won't be able
2180         * to make progress. The page will be redirtied by
2181         * writepage and writepages will again try to write
2182         * the same.
2183         */
2184        printk(KERN_EMERG "%s block allocation failed for inode %lu "
2185                  "at logical offset %llu with max blocks "
2186                  "%zd with error %d\n",
2187                  __func__, mpd->inode->i_ino,
2188                  (unsigned long long)next,
2189                  mpd->b_size >> mpd->inode->i_blkbits, err);
2190        printk(KERN_EMERG "This should not happen.!! "
2191                    "Data will be lost\n");
2192        if (err == -ENOSPC) {
2193            ext4_print_free_blocks(mpd->inode);
2194        }
2195        /* invalidate all the pages */
2196        ext4_da_block_invalidatepages(mpd, next,
2197                mpd->b_size >> mpd->inode->i_blkbits);
2198        return err;
2199    }
2200    BUG_ON(blks == 0);
2201
2202    new.b_size = (blks << mpd->inode->i_blkbits);
2203
2204    if (buffer_new(&new))
2205        __unmap_underlying_blocks(mpd->inode, &new);
2206
2207    /*
2208     * If blocks are delayed marked, we need to
2209     * put actual blocknr and drop delayed bit
2210     */
2211    if ((mpd->b_state & (1 << BH_Delay)) ||
2212        (mpd->b_state & (1 << BH_Unwritten)))
2213        mpage_put_bnr_to_bhs(mpd, next, &new);
2214
2215    if (ext4_should_order_data(mpd->inode)) {
2216        err = ext4_jbd2_file_inode(handle, mpd->inode);
2217        if (err)
2218            return err;
2219    }
2220
2221    /*
2222     * Update on-disk size along with block allocation.
2223     */
2224    disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
2225    if (disksize > i_size_read(mpd->inode))
2226        disksize = i_size_read(mpd->inode);
2227    if (disksize > EXT4_I(mpd->inode)->i_disksize) {
2228        ext4_update_i_disksize(mpd->inode, disksize);
2229        return ext4_mark_inode_dirty(handle, mpd->inode);
2230    }
2231
2232    return 0;
2233}
2234
2235#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
2236        (1 << BH_Delay) | (1 << BH_Unwritten))
2237
2238/*
2239 * mpage_add_bh_to_extent - try to add one more block to extent of blocks
2240 *
2241 * @mpd->lbh - extent of blocks
2242 * @logical - logical number of the block in the file
2243 * @bh - bh of the block (used to access block's state)
2244 *
2245 * the function is used to collect contig. blocks in same state
2246 */
2247static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
2248                   sector_t logical, size_t b_size,
2249                   unsigned long b_state)
2250{
2251    sector_t next;
2252    int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
2253
2254    /* check if thereserved journal credits might overflow */
2255    if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) {
2256        if (nrblocks >= EXT4_MAX_TRANS_DATA) {
2257            /*
2258             * With non-extent format we are limited by the journal
2259             * credit available. Total credit needed to insert
2260             * nrblocks contiguous blocks is dependent on the
2261             * nrblocks. So limit nrblocks.
2262             */
2263            goto flush_it;
2264        } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
2265                EXT4_MAX_TRANS_DATA) {
2266            /*
2267             * Adding the new buffer_head would make it cross the
2268             * allowed limit for which we have journal credit
2269             * reserved. So limit the new bh->b_size
2270             */
2271            b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
2272                        mpd->inode->i_blkbits;
2273            /* we will do mpage_da_submit_io in the next loop */
2274        }
2275    }
2276    /*
2277     * First block in the extent
2278     */
2279    if (mpd->b_size == 0) {
2280        mpd->b_blocknr = logical;
2281        mpd->b_size = b_size;
2282        mpd->b_state = b_state & BH_FLAGS;
2283        return;
2284    }
2285
2286    next = mpd->b_blocknr + nrblocks;
2287    /*
2288     * Can we merge the block to our big extent?
2289     */
2290    if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
2291        mpd->b_size += b_size;
2292        return;
2293    }
2294
2295flush_it:
2296    /*
2297     * We couldn't merge the block to our extent, so we
2298     * need to flush current extent and start new one
2299     */
2300    if (mpage_da_map_blocks(mpd) == 0)
2301        mpage_da_submit_io(mpd);
2302    mpd->io_done = 1;
2303    return;
2304}
2305
2306static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
2307{
2308    return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
2309}
2310
2311/*
2312 * __mpage_da_writepage - finds extent of pages and blocks
2313 *
2314 * @page: page to consider
2315 * @wbc: not used, we just follow rules
2316 * @data: context
2317 *
2318 * The function finds extents of pages and scan them for all blocks.
2319 */
2320static int __mpage_da_writepage(struct page *page,
2321                struct writeback_control *wbc, void *data)
2322{
2323    struct mpage_da_data *mpd = data;
2324    struct inode *inode = mpd->inode;
2325    struct buffer_head *bh, *head;
2326    sector_t logical;
2327
2328    if (mpd->io_done) {
2329        /*
2330         * Rest of the page in the page_vec
2331         * redirty then and skip then. We will
2332         * try to to write them again after
2333         * starting a new transaction
2334         */
2335        redirty_page_for_writepage(wbc, page);
2336        unlock_page(page);
2337        return MPAGE_DA_EXTENT_TAIL;
2338    }
2339    /*
2340     * Can we merge this page to current extent?
2341     */
2342    if (mpd->next_page != page->index) {
2343        /*
2344         * Nope, we can't. So, we map non-allocated blocks
2345         * and start IO on them using writepage()
2346         */
2347        if (mpd->next_page != mpd->first_page) {
2348            if (mpage_da_map_blocks(mpd) == 0)
2349                mpage_da_submit_io(mpd);
2350            /*
2351             * skip rest of the page in the page_vec
2352             */
2353            mpd->io_done = 1;
2354            redirty_page_for_writepage(wbc, page);
2355            unlock_page(page);
2356            return MPAGE_DA_EXTENT_TAIL;
2357        }
2358
2359        /*
2360         * Start next extent of pages ...
2361         */
2362        mpd->first_page = page->index;
2363
2364        /*
2365         * ... and blocks
2366         */
2367        mpd->b_size = 0;
2368        mpd->b_state = 0;
2369        mpd->b_blocknr = 0;
2370    }
2371
2372    mpd->next_page = page->index + 1;
2373    logical = (sector_t) page->index <<
2374          (PAGE_CACHE_SHIFT - inode->i_blkbits);
2375
2376    if (!page_has_buffers(page)) {
2377        mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE,
2378                       (1 << BH_Dirty) | (1 << BH_Uptodate));
2379        if (mpd->io_done)
2380            return MPAGE_DA_EXTENT_TAIL;
2381    } else {
2382        /*
2383         * Page with regular buffer heads, just add all dirty ones
2384         */
2385        head = page_buffers(page);
2386        bh = head;
2387        do {
2388            BUG_ON(buffer_locked(bh));
2389            /*
2390             * We need to try to allocate
2391             * unmapped blocks in the same page.
2392             * Otherwise we won't make progress
2393             * with the page in ext4_writepage
2394             */
2395            if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2396                mpage_add_bh_to_extent(mpd, logical,
2397                               bh->b_size,
2398                               bh->b_state);
2399                if (mpd->io_done)
2400                    return MPAGE_DA_EXTENT_TAIL;
2401            } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
2402                /*
2403                 * mapped dirty buffer. We need to update
2404                 * the b_state because we look at
2405                 * b_state in mpage_da_map_blocks. We don't
2406                 * update b_size because if we find an
2407                 * unmapped buffer_head later we need to
2408                 * use the b_state flag of that buffer_head.
2409                 */
2410                if (mpd->b_size == 0)
2411                    mpd->b_state = bh->b_state & BH_FLAGS;
2412            }
2413            logical++;
2414        } while ((bh = bh->b_this_page) != head);
2415    }
2416
2417    return 0;
2418}
2419
2420/*
2421 * This is a special get_blocks_t callback which is used by
2422 * ext4_da_write_begin(). It will either return mapped block or
2423 * reserve space for a single block.
2424 *
2425 * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
2426 * We also have b_blocknr = -1 and b_bdev initialized properly
2427 *
2428 * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
2429 * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
2430 * initialized properly.
2431 */
2432static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
2433                  struct buffer_head *bh_result, int create)
2434{
2435    int ret = 0;
2436    sector_t invalid_block = ~((sector_t) 0xffff);
2437
2438    if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
2439        invalid_block = ~0;
2440
2441    BUG_ON(create == 0);
2442    BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2443
2444    /*
2445     * first, we need to know whether the block is allocated already
2446     * preallocated blocks are unmapped but should treated
2447     * the same as allocated blocks.
2448     */
2449    ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0);
2450    if ((ret == 0) && !buffer_delay(bh_result)) {
2451        /* the block isn't (pre)allocated yet, let's reserve space */
2452        /*
2453         * XXX: __block_prepare_write() unmaps passed block,
2454         * is it OK?
2455         */
2456        ret = ext4_da_reserve_space(inode, 1);
2457        if (ret)
2458            /* not enough space to reserve */
2459            return ret;
2460
2461        map_bh(bh_result, inode->i_sb, invalid_block);
2462        set_buffer_new(bh_result);
2463        set_buffer_delay(bh_result);
2464    } else if (ret > 0) {
2465        bh_result->b_size = (ret << inode->i_blkbits);
2466        if (buffer_unwritten(bh_result)) {
2467            /* A delayed write to unwritten bh should
2468             * be marked new and mapped. Mapped ensures
2469             * that we don't do get_block multiple times
2470             * when we write to the same offset and new
2471             * ensures that we do proper zero out for
2472             * partial write.
2473             */
2474            set_buffer_new(bh_result);
2475            set_buffer_mapped(bh_result);
2476        }
2477        ret = 0;
2478    }
2479
2480    return ret;
2481}
2482
2483/*
2484 * This function is used as a standard get_block_t calback function
2485 * when there is no desire to allocate any blocks. It is used as a
2486 * callback function for block_prepare_write(), nobh_writepage(), and
2487 * block_write_full_page(). These functions should only try to map a
2488 * single block at a time.
2489 *
2490 * Since this function doesn't do block allocations even if the caller
2491 * requests it by passing in create=1, it is critically important that
2492 * any caller checks to make sure that any buffer heads are returned
2493 * by this function are either all already mapped or marked for
2494 * delayed allocation before calling nobh_writepage() or
2495 * block_write_full_page(). Otherwise, b_blocknr could be left
2496 * unitialized, and the page write functions will be taken by
2497 * surprise.
2498 */
2499static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
2500                   struct buffer_head *bh_result, int create)
2501{
2502    int ret = 0;
2503    unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
2504
2505    BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2506
2507    /*
2508     * we don't want to do block allocation in writepage
2509     * so call get_block_wrap with create = 0
2510     */
2511    ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
2512    if (ret > 0) {
2513        bh_result->b_size = (ret << inode->i_blkbits);
2514        ret = 0;
2515    }
2516    return ret;
2517}
2518
2519static int bget_one(handle_t *handle, struct buffer_head *bh)
2520{
2521    get_bh(bh);
2522    return 0;
2523}
2524
2525static int bput_one(handle_t *handle, struct buffer_head *bh)
2526{
2527    put_bh(bh);
2528    return 0;
2529}
2530
2531static int __ext4_journalled_writepage(struct page *page,
2532                       struct writeback_control *wbc,
2533                       unsigned int len)
2534{
2535    struct address_space *mapping = page->mapping;
2536    struct inode *inode = mapping->host;
2537    struct buffer_head *page_bufs;
2538    handle_t *handle = NULL;
2539    int ret = 0;
2540    int err;
2541
2542    page_bufs = page_buffers(page);
2543    BUG_ON(!page_bufs);
2544    walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
2545    /* As soon as we unlock the page, it can go away, but we have
2546     * references to buffers so we are safe */
2547    unlock_page(page);
2548
2549    handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
2550    if (IS_ERR(handle)) {
2551        ret = PTR_ERR(handle);
2552        goto out;
2553    }
2554
2555    ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2556                do_journal_get_write_access);
2557
2558    err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2559                write_end_fn);
2560    if (ret == 0)
2561        ret = err;
2562    err = ext4_journal_stop(handle);
2563    if (!ret)
2564        ret = err;
2565
2566    walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
2567    EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
2568out:
2569    return ret;
2570}
2571
2572/*
2573 * Note that we don't need to start a transaction unless we're journaling data
2574 * because we should have holes filled from ext4_page_mkwrite(). We even don't
2575 * need to file the inode to the transaction's list in ordered mode because if
2576 * we are writing back data added by write(), the inode is already there and if
2577 * we are writing back data modified via mmap(), noone guarantees in which
2578 * transaction the data will hit the disk. In case we are journaling data, we
2579 * cannot start transaction directly because transaction start ranks above page
2580 * lock so we have to do some magic.
2581 *
2582 * This function can get called via...
2583 * - ext4_da_writepages after taking page lock (have journal handle)
2584 * - journal_submit_inode_data_buffers (no journal handle)
2585 * - shrink_page_list via pdflush (no journal handle)
2586 * - grab_page_cache when doing write_begin (have journal handle)
2587 *
2588 * We don't do any block allocation in this function. If we have page with
2589 * multiple blocks we need to write those buffer_heads that are mapped. This
2590 * is important for mmaped based write. So if we do with blocksize 1K
2591 * truncate(f, 1024);
2592 * a = mmap(f, 0, 4096);
2593 * a[0] = 'a';
2594 * truncate(f, 4096);
2595 * we have in the page first buffer_head mapped via page_mkwrite call back
2596 * but other bufer_heads would be unmapped but dirty(dirty done via the
2597 * do_wp_page). So writepage should write the first block. If we modify
2598 * the mmap area beyond 1024 we will again get a page_fault and the
2599 * page_mkwrite callback will do the block allocation and mark the
2600 * buffer_heads mapped.
2601 *
2602 * We redirty the page if we have any buffer_heads that is either delay or
2603 * unwritten in the page.
2604 *
2605 * We can get recursively called as show below.
2606 *
2607 * ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2608 * ext4_writepage()
2609 *
2610 * But since we don't do any block allocation we should not deadlock.
2611 * Page also have the dirty flag cleared so we don't get recurive page_lock.
2612 */
2613static int ext4_writepage(struct page *page,
2614              struct writeback_control *wbc)
2615{
2616    int ret = 0;
2617    loff_t size;
2618    unsigned int len;
2619    struct buffer_head *page_bufs;
2620    struct inode *inode = page->mapping->host;
2621
2622    trace_ext4_writepage(inode, page);
2623    size = i_size_read(inode);
2624    if (page->index == size >> PAGE_CACHE_SHIFT)
2625        len = size & ~PAGE_CACHE_MASK;
2626    else
2627        len = PAGE_CACHE_SIZE;
2628
2629    if (page_has_buffers(page)) {
2630        page_bufs = page_buffers(page);
2631        if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2632                    ext4_bh_delay_or_unwritten)) {
2633            /*
2634             * We don't want to do block allocation
2635             * So redirty the page and return
2636             * We may reach here when we do a journal commit
2637             * via journal_submit_inode_data_buffers.
2638             * If we don't have mapping block we just ignore
2639             * them. We can also reach here via shrink_page_list
2640             */
2641            redirty_page_for_writepage(wbc, page);
2642            unlock_page(page);
2643            return 0;
2644        }
2645    } else {
2646        /*
2647         * The test for page_has_buffers() is subtle:
2648         * We know the page is dirty but it lost buffers. That means
2649         * that at some moment in time after write_begin()/write_end()
2650         * has been called all buffers have been clean and thus they
2651         * must have been written at least once. So they are all
2652         * mapped and we can happily proceed with mapping them
2653         * and writing the page.
2654         *
2655         * Try to initialize the buffer_heads and check whether
2656         * all are mapped and non delay. We don't want to
2657         * do block allocation here.
2658         */
2659        ret = block_prepare_write(page, 0, len,
2660                      noalloc_get_block_write);
2661        if (!ret) {
2662            page_bufs = page_buffers(page);
2663            /* check whether all are mapped and non delay */
2664            if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2665                        ext4_bh_delay_or_unwritten)) {
2666                redirty_page_for_writepage(wbc, page);
2667                unlock_page(page);
2668                return 0;
2669            }
2670        } else {
2671            /*
2672             * We can't do block allocation here
2673             * so just redity the page and unlock
2674             * and return
2675             */
2676            redirty_page_for_writepage(wbc, page);
2677            unlock_page(page);
2678            return 0;
2679        }
2680        /* now mark the buffer_heads as dirty and uptodate */
2681        block_commit_write(page, 0, len);
2682    }
2683
2684    if (PageChecked(page) && ext4_should_journal_data(inode)) {
2685        /*
2686         * It's mmapped pagecache. Add buffers and journal it. There
2687         * doesn't seem much point in redirtying the page here.
2688         */
2689        ClearPageChecked(page);
2690        return __ext4_journalled_writepage(page, wbc, len);
2691    }
2692
2693    if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
2694        ret = nobh_writepage(page, noalloc_get_block_write, wbc);
2695    else
2696        ret = block_write_full_page(page, noalloc_get_block_write,
2697                        wbc);
2698
2699    return ret;
2700}
2701
2702/*
2703 * This is called via ext4_da_writepages() to
2704 * calulate the total number of credits to reserve to fit
2705 * a single extent allocation into a single transaction,
2706 * ext4_da_writpeages() will loop calling this before
2707 * the block allocation.
2708 */
2709
2710static int ext4_da_writepages_trans_blocks(struct inode *inode)
2711{
2712    int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2713
2714    /*
2715     * With non-extent format the journal credit needed to
2716     * insert nrblocks contiguous block is dependent on
2717     * number of contiguous block. So we will limit
2718     * number of contiguous block to a sane value
2719     */
2720    if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
2721        (max_blocks > EXT4_MAX_TRANS_DATA))
2722        max_blocks = EXT4_MAX_TRANS_DATA;
2723
2724    return ext4_chunk_trans_blocks(inode, max_blocks);
2725}
2726
2727static int ext4_da_writepages(struct address_space *mapping,
2728                  struct writeback_control *wbc)
2729{
2730    pgoff_t index;
2731    int range_whole = 0;
2732    handle_t *handle = NULL;
2733    struct mpage_da_data mpd;
2734    struct inode *inode = mapping->host;
2735    int no_nrwrite_index_update;
2736    int pages_written = 0;
2737    long pages_skipped;
2738    int range_cyclic, cycled = 1, io_done = 0;
2739    int needed_blocks, ret = 0, nr_to_writebump = 0;
2740    struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2741
2742    trace_ext4_da_writepages(inode, wbc);
2743
2744    /*
2745     * No pages to write? This is mainly a kludge to avoid starting
2746     * a transaction for special inodes like journal inode on last iput()
2747     * because that could violate lock ordering on umount
2748     */
2749    if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2750        return 0;
2751
2752    /*
2753     * If the filesystem has aborted, it is read-only, so return
2754     * right away instead of dumping stack traces later on that
2755     * will obscure the real source of the problem. We test
2756     * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2757     * the latter could be true if the filesystem is mounted
2758     * read-only, and in that case, ext4_da_writepages should
2759     * *never* be called, so if that ever happens, we would want
2760     * the stack trace.
2761     */
2762    if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2763        return -EROFS;
2764
2765    /*
2766     * Make sure nr_to_write is >= sbi->s_mb_stream_request
2767     * This make sure small files blocks are allocated in
2768     * single attempt. This ensure that small files
2769     * get less fragmented.
2770     */
2771    if (wbc->nr_to_write < sbi->s_mb_stream_request) {
2772        nr_to_writebump = sbi->s_mb_stream_request - wbc->nr_to_write;
2773        wbc->nr_to_write = sbi->s_mb_stream_request;
2774    }
2775    if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2776        range_whole = 1;
2777
2778    range_cyclic = wbc->range_cyclic;
2779    if (wbc->range_cyclic) {
2780        index = mapping->writeback_index;
2781        if (index)
2782            cycled = 0;
2783        wbc->range_start = index << PAGE_CACHE_SHIFT;
2784        wbc->range_end = LLONG_MAX;
2785        wbc->range_cyclic = 0;
2786    } else
2787        index = wbc->range_start >> PAGE_CACHE_SHIFT;
2788
2789    mpd.wbc = wbc;
2790    mpd.inode = mapping->host;
2791
2792    /*
2793     * we don't want write_cache_pages to update
2794     * nr_to_write and writeback_index
2795     */
2796    no_nrwrite_index_update = wbc->no_nrwrite_index_update;
2797    wbc->no_nrwrite_index_update = 1;
2798    pages_skipped = wbc->pages_skipped;
2799
2800retry:
2801    while (!ret && wbc->nr_to_write > 0) {
2802
2803        /*
2804         * we insert one extent at a time. So we need
2805         * credit needed for single extent allocation.
2806         * journalled mode is currently not supported
2807         * by delalloc
2808         */
2809        BUG_ON(ext4_should_journal_data(inode));
2810        needed_blocks = ext4_da_writepages_trans_blocks(inode);
2811
2812        /* start a new transaction*/
2813        handle = ext4_journal_start(inode, needed_blocks);
2814        if (IS_ERR(handle)) {
2815            ret = PTR_ERR(handle);
2816            printk(KERN_CRIT "%s: jbd2_start: "
2817                   "%ld pages, ino %lu; err %d\n", __func__,
2818                wbc->nr_to_write, inode->i_ino, ret);
2819            dump_stack();
2820            goto out_writepages;
2821        }
2822
2823        /*
2824         * Now call __mpage_da_writepage to find the next
2825         * contiguous region of logical blocks that need
2826         * blocks to be allocated by ext4. We don't actually
2827         * submit the blocks for I/O here, even though
2828         * write_cache_pages thinks it will, and will set the
2829         * pages as clean for write before calling
2830         * __mpage_da_writepage().
2831         */
2832        mpd.b_size = 0;
2833        mpd.b_state = 0;
2834        mpd.b_blocknr = 0;
2835        mpd.first_page = 0;
2836        mpd.next_page = 0;
2837        mpd.io_done = 0;
2838        mpd.pages_written = 0;
2839        mpd.retval = 0;
2840        ret = write_cache_pages(mapping, wbc, __mpage_da_writepage,
2841                    &mpd);
2842        /*
2843         * If we have a contigous extent of pages and we
2844         * haven't done the I/O yet, map the blocks and submit
2845         * them for I/O.
2846         */
2847        if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2848            if (mpage_da_map_blocks(&mpd) == 0)
2849                mpage_da_submit_io(&mpd);
2850            mpd.io_done = 1;
2851            ret = MPAGE_DA_EXTENT_TAIL;
2852        }
2853        wbc->nr_to_write -= mpd.pages_written;
2854
2855        ext4_journal_stop(handle);
2856
2857        if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2858            /* commit the transaction which would
2859             * free blocks released in the transaction
2860             * and try again
2861             */
2862            jbd2_journal_force_commit_nested(sbi->s_journal);
2863            wbc->pages_skipped = pages_skipped;
2864            ret = 0;
2865        } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2866            /*
2867             * got one extent now try with
2868             * rest of the pages
2869             */
2870            pages_written += mpd.pages_written;
2871            wbc->pages_skipped = pages_skipped;
2872            ret = 0;
2873            io_done = 1;
2874        } else if (wbc->nr_to_write)
2875            /*
2876             * There is no more writeout needed
2877             * or we requested for a noblocking writeout
2878             * and we found the device congested
2879             */
2880            break;
2881    }
2882    if (!io_done && !cycled) {
2883        cycled = 1;
2884        index = 0;
2885        wbc->range_start = index << PAGE_CACHE_SHIFT;
2886        wbc->range_end = mapping->writeback_index - 1;
2887        goto retry;
2888    }
2889    if (pages_skipped != wbc->pages_skipped)
2890        printk(KERN_EMERG "This should not happen leaving %s "
2891                "with nr_to_write = %ld ret = %d\n",
2892                __func__, wbc->nr_to_write, ret);
2893
2894    /* Update index */
2895    index += pages_written;
2896    wbc->range_cyclic = range_cyclic;
2897    if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2898        /*
2899         * set the writeback_index so that range_cyclic
2900         * mode will write it back later
2901         */
2902        mapping->writeback_index = index;
2903
2904out_writepages:
2905    if (!no_nrwrite_index_update)
2906        wbc->no_nrwrite_index_update = 0;
2907    wbc->nr_to_write -= nr_to_writebump;
2908    trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2909    return ret;
2910}
2911
2912#define FALL_BACK_TO_NONDELALLOC 1
2913static int ext4_nonda_switch(struct super_block *sb)
2914{
2915    s64 free_blocks, dirty_blocks;
2916    struct ext4_sb_info *sbi = EXT4_SB(sb);
2917
2918    /*
2919     * switch to non delalloc mode if we are running low
2920     * on free block. The free block accounting via percpu
2921     * counters can get slightly wrong with percpu_counter_batch getting
2922     * accumulated on each CPU without updating global counters
2923     * Delalloc need an accurate free block accounting. So switch
2924     * to non delalloc when we are near to error range.
2925     */
2926    free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
2927    dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter);
2928    if (2 * free_blocks < 3 * dirty_blocks ||
2929        free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
2930        /*
2931         * free block count is less that 150% of dirty blocks
2932         * or free blocks is less that watermark
2933         */
2934        return 1;
2935    }
2936    return 0;
2937}
2938
2939static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2940                   loff_t pos, unsigned len, unsigned flags,
2941                   struct page **pagep, void **fsdata)
2942{
2943    int ret, retries = 0;
2944    struct page *page;
2945    pgoff_t index;
2946    unsigned from, to;
2947    struct inode *inode = mapping->host;
2948    handle_t *handle;
2949
2950    index = pos >> PAGE_CACHE_SHIFT;
2951    from = pos & (PAGE_CACHE_SIZE - 1);
2952    to = from + len;
2953
2954    if (ext4_nonda_switch(inode->i_sb)) {
2955        *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2956        return ext4_write_begin(file, mapping, pos,
2957                    len, flags, pagep, fsdata);
2958    }
2959    *fsdata = (void *)0;
2960    trace_ext4_da_write_begin(inode, pos, len, flags);
2961retry:
2962    /*
2963     * With delayed allocation, we don't log the i_disksize update
2964     * if there is delayed block allocation. But we still need
2965     * to journalling the i_disksize update if writes to the end
2966     * of file which has an already mapped buffer.
2967     */
2968    handle = ext4_journal_start(inode, 1);
2969    if (IS_ERR(handle)) {
2970        ret = PTR_ERR(handle);
2971        goto out;
2972    }
2973    /* We cannot recurse into the filesystem as the transaction is already
2974     * started */
2975    flags |= AOP_FLAG_NOFS;
2976
2977    page = grab_cache_page_write_begin(mapping, index, flags);
2978    if (!page) {
2979        ext4_journal_stop(handle);
2980        ret = -ENOMEM;
2981        goto out;
2982    }
2983    *pagep = page;
2984
2985    ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
2986                ext4_da_get_block_prep);
2987    if (ret < 0) {
2988        unlock_page(page);
2989        ext4_journal_stop(handle);
2990        page_cache_release(page);
2991        /*
2992         * block_write_begin may have instantiated a few blocks
2993         * outside i_size. Trim these off again. Don't need
2994         * i_size_read because we hold i_mutex.
2995         */
2996        if (pos + len > inode->i_size)
2997            ext4_truncate(inode);
2998    }
2999
3000    if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
3001        goto retry;
3002out:
3003    return ret;
3004}
3005
3006/*
3007 * Check if we should update i_disksize
3008 * when write to the end of file but not require block allocation
3009 */
3010static int ext4_da_should_update_i_disksize(struct page *page,
3011                        unsigned long offset)
3012{
3013    struct buffer_head *bh;
3014    struct inode *inode = page->mapping->host;
3015    unsigned int idx;
3016    int i;
3017
3018    bh = page_buffers(page);
3019    idx = offset >> inode->i_blkbits;
3020
3021    for (i = 0; i < idx; i++)
3022        bh = bh->b_this_page;
3023
3024    if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3025        return 0;
3026    return 1;
3027}
3028
3029static int ext4_da_write_end(struct file *file,
3030                 struct address_space *mapping,
3031                 loff_t pos, unsigned len, unsigned copied,
3032                 struct page *page, void *fsdata)
3033{
3034    struct inode *inode = mapping->host;
3035    int ret = 0, ret2;
3036    handle_t *handle = ext4_journal_current_handle();
3037    loff_t new_i_size;
3038    unsigned long start, end;
3039    int write_mode = (int)(unsigned long)fsdata;
3040
3041    if (write_mode == FALL_BACK_TO_NONDELALLOC) {
3042        if (ext4_should_order_data(inode)) {
3043            return ext4_ordered_write_end(file, mapping, pos,
3044                    len, copied, page, fsdata);
3045        } else if (ext4_should_writeback_data(inode)) {
3046            return ext4_writeback_write_end(file, mapping, pos,
3047                    len, copied, page, fsdata);
3048        } else {
3049            BUG();
3050        }
3051    }
3052
3053    trace_ext4_da_write_end(inode, pos, len, copied);
3054    start = pos & (PAGE_CACHE_SIZE - 1);
3055    end = start + copied - 1;
3056
3057    /*
3058     * generic_write_end() will run mark_inode_dirty() if i_size
3059     * changes. So let's piggyback the i_disksize mark_inode_dirty
3060     * into that.
3061     */
3062
3063    new_i_size = pos + copied;
3064    if (new_i_size > EXT4_I(inode)->i_disksize) {
3065        if (ext4_da_should_update_i_disksize(page, end)) {
3066            down_write(&EXT4_I(inode)->i_data_sem);
3067            if (new_i_size > EXT4_I(inode)->i_disksize) {
3068                /*
3069                 * Updating i_disksize when extending file
3070                 * without needing block allocation
3071                 */
3072                if (ext4_should_order_data(inode))
3073                    ret = ext4_jbd2_file_inode(handle,
3074                                   inode);
3075
3076                EXT4_I(inode)->i_disksize = new_i_size;
3077            }
3078            up_write(&EXT4_I(inode)->i_data_sem);
3079            /* We need to mark inode dirty even if
3080             * new_i_size is less that inode->i_size
3081             * bu greater than i_disksize.(hint delalloc)
3082             */
3083            ext4_mark_inode_dirty(handle, inode);
3084        }
3085    }
3086    ret2 = generic_write_end(file, mapping, pos, len, copied,
3087                            page, fsdata);
3088    copied = ret2;
3089    if (ret2 < 0)
3090        ret = ret2;
3091    ret2 = ext4_journal_stop(handle);
3092    if (!ret)
3093        ret = ret2;
3094
3095    return ret ? ret : copied;
3096}
3097
3098static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
3099{
3100    /*
3101     * Drop reserved blocks
3102     */
3103    BUG_ON(!PageLocked(page));
3104    if (!page_has_buffers(page))
3105        goto out;
3106
3107    ext4_da_page_release_reservation(page, offset);
3108
3109out:
3110    ext4_invalidatepage(page, offset);
3111
3112    return;
3113}
3114
3115/*
3116 * Force all delayed allocation blocks to be allocated for a given inode.
3117 */
3118int ext4_alloc_da_blocks(struct inode *inode)
3119{
3120    if (!EXT4_I(inode)->i_reserved_data_blocks &&
3121        !EXT4_I(inode)->i_reserved_meta_blocks)
3122        return 0;
3123
3124    /*
3125     * We do something simple for now. The filemap_flush() will
3126     * also start triggering a write of the data blocks, which is
3127     * not strictly speaking necessary (and for users of
3128     * laptop_mode, not even desirable). However, to do otherwise
3129     * would require replicating code paths in:
3130     *
3131     * ext4_da_writepages() ->
3132     * write_cache_pages() ---> (via passed in callback function)
3133     * __mpage_da_writepage() -->
3134     * mpage_add_bh_to_extent()
3135     * mpage_da_map_blocks()
3136     *
3137     * The problem is that write_cache_pages(), located in
3138     * mm/page-writeback.c, marks pages clean in preparation for
3139     * doing I/O, which is not desirable if we're not planning on
3140     * doing I/O at all.
3141     *
3142     * We could call write_cache_pages(), and then redirty all of
3143     * the pages by calling redirty_page_for_writeback() but that
3144     * would be ugly in the extreme. So instead we would need to
3145     * replicate parts of the code in the above functions,
3146     * simplifying them becuase we wouldn't actually intend to
3147     * write out the pages, but rather only collect contiguous
3148     * logical block extents, call the multi-block allocator, and
3149     * then update the buffer heads with the block allocations.
3150     *
3151     * For now, though, we'll cheat by calling filemap_flush(),
3152     * which will map the blocks, and start the I/O, but not
3153     * actually wait for the I/O to complete.
3154     */
3155    return filemap_flush(inode->i_mapping);
3156}
3157
3158/*
3159 * bmap() is special. It gets used by applications such as lilo and by
3160 * the swapper to find the on-disk block of a specific piece of data.
3161 *
3162 * Naturally, this is dangerous if the block concerned is still in the
3163 * journal. If somebody makes a swapfile on an ext4 data-journaling
3164 * filesystem and enables swap, then they may get a nasty shock when the
3165 * data getting swapped to that swapfile suddenly gets overwritten by
3166 * the original zero's written out previously to the journal and
3167 * awaiting writeback in the kernel's buffer cache.
3168 *
3169 * So, if we see any bmap calls here on a modified, data-journaled file,
3170 * take extra steps to flush any blocks which might be in the cache.
3171 */
3172static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3173{
3174    struct inode *inode = mapping->host;
3175    journal_t *journal;
3176    int err;
3177
3178    if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3179            test_opt(inode->i_sb, DELALLOC)) {
3180        /*
3181         * With delalloc we want to sync the file
3182         * so that we can make sure we allocate
3183         * blocks for file
3184         */
3185        filemap_write_and_wait(mapping);
3186    }
3187
3188    if (EXT4_JOURNAL(inode) && EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
3189        /*
3190         * This is a REALLY heavyweight approach, but the use of
3191         * bmap on dirty files is expected to be extremely rare:
3192         * only if we run lilo or swapon on a freshly made file
3193         * do we expect this to happen.
3194         *
3195         * (bmap requires CAP_SYS_RAWIO so this does not
3196         * represent an unprivileged user DOS attack --- we'd be
3197         * in trouble if mortal users could trigger this path at
3198         * will.)
3199         *
3200         * NB. EXT4_STATE_JDATA is not set on files other than
3201         * regular files. If somebody wants to bmap a directory
3202         * or symlink and gets confused because the buffer
3203         * hasn't yet been flushed to disk, they deserve
3204         * everything they get.
3205         */
3206
3207        EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
3208        journal = EXT4_JOURNAL(inode);
3209        jbd2_journal_lock_updates(journal);
3210        err = jbd2_journal_flush(journal);
3211        jbd2_journal_unlock_updates(journal);
3212
3213        if (err)
3214            return 0;
3215    }
3216
3217    return generic_block_bmap(mapping, block, ext4_get_block);
3218}
3219
3220static int ext4_readpage(struct file *file, struct page *page)
3221{
3222    return mpage_readpage(page, ext4_get_block);
3223}
3224
3225static int
3226ext4_readpages(struct file *file, struct address_space *mapping,
3227        struct list_head *pages, unsigned nr_pages)
3228{
3229    return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
3230}
3231
3232static void ext4_invalidatepage(struct page *page, unsigned long offset)
3233{
3234    journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3235
3236    /*
3237     * If it's a full truncate we just forget about the pending dirtying
3238     */
3239    if (offset == 0)
3240        ClearPageChecked(page);
3241
3242    if (journal)
3243        jbd2_journal_invalidatepage(journal, page, offset);
3244    else
3245        block_invalidatepage(page, offset);
3246}
3247
3248static int ext4_releasepage(struct page *page, gfp_t wait)
3249{
3250    journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3251
3252    WARN_ON(PageChecked(page));
3253    if (!page_has_buffers(page))
3254        return 0;
3255    if (journal)
3256        return jbd2_journal_try_to_free_buffers(journal, page, wait);
3257    else
3258        return try_to_free_buffers(page);
3259}
3260
3261/*
3262 * If the O_DIRECT write will extend the file then add this inode to the
3263 * orphan list. So recovery will truncate it back to the original size
3264 * if the machine crashes during the write.
3265 *
3266 * If the O_DIRECT write is intantiating holes inside i_size and the machine
3267 * crashes then stale disk data _may_ be exposed inside the file. But current
3268 * VFS code falls back into buffered path in that case so we are safe.
3269 */
3270static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
3271                  const struct iovec *iov, loff_t offset,
3272                  unsigned long nr_segs)
3273{
3274    struct file *file = iocb->ki_filp;
3275    struct inode *inode = file->f_mapping->host;
3276    struct ext4_inode_info *ei = EXT4_I(inode);
3277    handle_t *handle;
3278    ssize_t ret;
3279    int orphan = 0;
3280    size_t count = iov_length(iov, nr_segs);
3281
3282    if (rw == WRITE) {
3283        loff_t final_size = offset + count;
3284
3285        if (final_size > inode->i_size) {
3286            /* Credits for sb + inode write */
3287            handle = ext4_journal_start(inode, 2);
3288            if (IS_ERR(handle)) {
3289                ret = PTR_ERR(handle);
3290                goto out;
3291            }
3292            ret = ext4_orphan_add(handle, inode);
3293            if (ret) {
3294                ext4_journal_stop(handle);
3295                goto out;
3296            }
3297            orphan = 1;
3298            ei->i_disksize = inode->i_size;
3299            ext4_journal_stop(handle);
3300        }
3301    }
3302
3303    ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
3304                 offset, nr_segs,
3305                 ext4_get_block, NULL);
3306
3307    if (orphan) {
3308        int err;
3309
3310        /* Credits for sb + inode write */
3311        handle = ext4_journal_start(inode, 2);
3312        if (IS_ERR(handle)) {
3313            /* This is really bad luck. We've written the data
3314             * but cannot extend i_size. Bail out and pretend
3315             * the write failed... */
3316            ret = PTR_ERR(handle);
3317            goto out;
3318        }
3319        if (inode->i_nlink)
3320            ext4_orphan_del(handle, inode);
3321        if (ret > 0) {
3322            loff_t end = offset + ret;
3323            if (end > inode->i_size) {
3324                ei->i_disksize = end;
3325                i_size_write(inode, end);
3326                /*
3327                 * We're going to return a positive `ret'
3328                 * here due to non-zero-length I/O, so there's
3329                 * no way of reporting error returns from
3330                 * ext4_mark_inode_dirty() to userspace. So
3331                 * ignore it.
3332                 */
3333                ext4_mark_inode_dirty(handle, inode);
3334            }
3335        }
3336        err = ext4_journal_stop(handle);
3337        if (ret == 0)
3338            ret = err;
3339    }
3340out:
3341    return ret;
3342}
3343
3344/*
3345 * Pages can be marked dirty completely asynchronously from ext4's journalling
3346 * activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do
3347 * much here because ->set_page_dirty is called under VFS locks. The page is
3348 * not necessarily locked.
3349 *
3350 * We cannot just dirty the page and leave attached buffers clean, because the
3351 * buffers' dirty state is "definitive". We cannot just set the buffers dirty
3352 * or jbddirty because all the journalling code will explode.
3353 *
3354 * So what we do is to mark the page "pending dirty" and next time writepage
3355 * is called, propagate that into the buffers appropriately.
3356 */
3357static int ext4_journalled_set_page_dirty(struct page *page)
3358{
3359    SetPageChecked(page);
3360    return __set_page_dirty_nobuffers(page);
3361}
3362
3363static const struct address_space_operations ext4_ordered_aops = {
3364    .readpage = ext4_readpage,
3365    .readpages = ext4_readpages,
3366    .writepage = ext4_writepage,
3367    .sync_page = block_sync_page,
3368    .write_begin = ext4_write_begin,
3369    .write_end = ext4_ordered_write_end,
3370    .bmap = ext4_bmap,
3371    .invalidatepage = ext4_invalidatepage,
3372    .releasepage = ext4_releasepage,
3373    .direct_IO = ext4_direct_IO,
3374    .migratepage = buffer_migrate_page,
3375    .is_partially_uptodate = block_is_partially_uptodate,
3376};
3377
3378static const struct address_space_operations ext4_writeback_aops = {
3379    .readpage = ext4_readpage,
3380    .readpages = ext4_readpages,
3381    .writepage = ext4_writepage,
3382    .sync_page = block_sync_page,
3383    .write_begin = ext4_write_begin,
3384    .write_end = ext4_writeback_write_end,
3385    .bmap = ext4_bmap,
3386    .invalidatepage = ext4_invalidatepage,
3387    .releasepage = ext4_releasepage,
3388    .direct_IO = ext4_direct_IO,
3389    .migratepage = buffer_migrate_page,
3390    .is_partially_uptodate = block_is_partially_uptodate,
3391};
3392
3393static const struct address_space_operations ext4_journalled_aops = {
3394    .readpage = ext4_readpage,
3395    .readpages = ext4_readpages,
3396    .writepage = ext4_writepage,
3397    .sync_page = block_sync_page,
3398    .write_begin = ext4_write_begin,
3399    .write_end = ext4_journalled_write_end,
3400    .set_page_dirty = ext4_journalled_set_page_dirty,
3401    .bmap = ext4_bmap,
3402    .invalidatepage = ext4_invalidatepage,
3403    .releasepage = ext4_releasepage,
3404    .is_partially_uptodate = block_is_partially_uptodate,
3405};
3406
3407static const struct address_space_operations ext4_da_aops = {
3408    .readpage = ext4_readpage,
3409    .readpages = ext4_readpages,
3410    .writepage = ext4_writepage,
3411    .writepages = ext4_da_writepages,
3412    .sync_page = block_sync_page,
3413    .write_begin = ext4_da_write_begin,
3414    .write_end = ext4_da_write_end,
3415    .bmap = ext4_bmap,
3416    .invalidatepage = ext4_da_invalidatepage,
3417    .releasepage = ext4_releasepage,
3418    .direct_IO = ext4_direct_IO,
3419    .migratepage = buffer_migrate_page,
3420    .is_partially_uptodate = block_is_partially_uptodate,
3421};
3422
3423void ext4_set_aops(struct inode *inode)
3424{
3425    if (ext4_should_order_data(inode) &&
3426        test_opt(inode->i_sb, DELALLOC))
3427        inode->i_mapping->a_ops = &ext4_da_aops;
3428    else if (ext4_should_order_data(inode))
3429        inode->i_mapping->a_ops = &ext4_ordered_aops;
3430    else if (ext4_should_writeback_data(inode) &&
3431         test_opt(inode->i_sb, DELALLOC))
3432        inode->i_mapping->a_ops = &ext4_da_aops;
3433    else if (ext4_should_writeback_data(inode))
3434        inode->i_mapping->a_ops = &ext4_writeback_aops;
3435    else
3436        inode->i_mapping->a_ops = &ext4_journalled_aops;
3437}
3438
3439/*
3440 * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
3441 * up to the end of the block which corresponds to `from'.
3442 * This required during truncate. We need to physically zero the tail end
3443 * of that block so it doesn't yield old data if the file is later grown.
3444 */
3445int ext4_block_truncate_page(handle_t *handle,
3446        struct address_space *mapping, loff_t from)
3447{
3448    ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
3449    unsigned offset = from & (PAGE_CACHE_SIZE-1);
3450    unsigned blocksize, length, pos;
3451    ext4_lblk_t iblock;
3452    struct inode *inode = mapping->host;
3453    struct buffer_head *bh;
3454    struct page *page;
3455    int err = 0;
3456
3457    page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
3458                   mapping_gfp_mask(mapping) & ~__GFP_FS);
3459    if (!page)
3460        return -EINVAL;
3461
3462    blocksize = inode->i_sb->s_blocksize;
3463    length = blocksize - (offset & (blocksize - 1));
3464    iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
3465
3466    /*
3467     * For "nobh" option, we can only work if we don't need to
3468     * read-in the page - otherwise we create buffers to do the IO.
3469     */
3470    if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
3471         ext4_should_writeback_data(inode) && PageUptodate(page)) {
3472        zero_user(page, offset, length);
3473        set_page_dirty(page);
3474        goto unlock;
3475    }
3476
3477    if (!page_has_buffers(page))
3478        create_empty_buffers(page, blocksize, 0);
3479
3480    /* Find the buffer that contains "offset" */
3481    bh = page_buffers(page);
3482    pos = blocksize;
3483    while (offset >= pos) {
3484        bh = bh->b_this_page;
3485        iblock++;
3486        pos += blocksize;
3487    }
3488
3489    err = 0;
3490    if (buffer_freed(bh)) {
3491        BUFFER_TRACE(bh, "freed: skip");
3492        goto unlock;
3493    }
3494
3495    if (!buffer_mapped(bh)) {
3496        BUFFER_TRACE(bh, "unmapped");
3497        ext4_get_block(inode, iblock, bh, 0);
3498        /* unmapped? It's a hole - nothing to do */
3499        if (!buffer_mapped(bh)) {
3500            BUFFER_TRACE(bh, "still unmapped");
3501            goto unlock;
3502        }
3503    }
3504
3505    /* Ok, it's mapped. Make sure it's up-to-date */
3506    if (PageUptodate(page))
3507        set_buffer_uptodate(bh);
3508
3509    if (!buffer_uptodate(bh)) {
3510        err = -EIO;
3511        ll_rw_block(READ, 1, &bh);
3512        wait_on_buffer(bh);
3513        /* Uhhuh. Read error. Complain and punt. */
3514        if (!buffer_uptodate(bh))
3515            goto unlock;
3516    }
3517
3518    if (ext4_should_journal_data(inode)) {
3519        BUFFER_TRACE(bh, "get write access");
3520        err = ext4_journal_get_write_access(handle, bh);
3521        if (err)
3522            goto unlock;
3523    }
3524
3525    zero_user(page, offset, length);
3526
3527    BUFFER_TRACE(bh, "zeroed end of block");
3528
3529    err = 0;
3530    if (ext4_should_journal_data(inode)) {
3531        err = ext4_handle_dirty_metadata(handle, inode, bh);
3532    } else {
3533        if (ext4_should_order_data(inode))
3534            err = ext4_jbd2_file_inode(handle, inode);
3535        mark_buffer_dirty(bh);
3536    }
3537
3538unlock:
3539    unlock_page(page);
3540    page_cache_release(page);
3541    return err;
3542}
3543
3544/*
3545 * Probably it should be a library function... search for first non-zero word
3546 * or memcmp with zero_page, whatever is better for particular architecture.
3547 * Linus?
3548 */
3549static inline int all_zeroes(__le32 *p, __le32 *q)
3550{
3551    while (p < q)
3552        if (*p++)
3553            return 0;
3554    return 1;
3555}
3556
3557/**
3558 * ext4_find_shared - find the indirect blocks for partial truncation.
3559 * @inode: inode in question
3560 * @depth: depth of the affected branch
3561 * @offsets: offsets of pointers in that branch (see ext4_block_to_path)
3562 * @chain: place to store the pointers to partial indirect blocks
3563 * @top: place to the (detached) top of branch
3564 *
3565 * This is a helper function used by ext4_truncate().
3566 *
3567 * When we do truncate() we may have to clean the ends of several
3568 * indirect blocks but leave the blocks themselves alive. Block is
3569 * partially truncated if some data below the new i_size is refered
3570 * from it (and it is on the path to the first completely truncated
3571 * data block, indeed). We have to free the top of that path along
3572 * with everything to the right of the path. Since no allocation
3573 * past the truncation point is possible until ext4_truncate()
3574 * finishes, we may safely do the latter, but top of branch may
3575 * require special attention - pageout below the truncation point
3576 * might try to populate it.
3577 *
3578 * We atomically detach the top of branch from the tree, store the
3579 * block number of its root in *@top, pointers to buffer_heads of
3580 * partially truncated blocks - in @chain[].bh and pointers to
3581 * their last elements that should not be removed - in
3582 * @chain[].p. Return value is the pointer to last filled element
3583 * of @chain.
3584 *
3585 * The work left to caller to do the actual freeing of subtrees:
3586 * a) free the subtree starting from *@top
3587 * b) free the subtrees whose roots are stored in
3588 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
3589 * c) free the subtrees growing from the inode past the @chain[0].
3590 * (no partially truncated stuff there). */
3591
3592static Indirect *ext4_find_shared(struct inode *inode, int depth,
3593                  ext4_lblk_t offsets[4], Indirect chain[4],
3594                  __le32 *top)
3595{
3596    Indirect *partial, *p;
3597    int k, err;
3598
3599    *top = 0;
3600    /* Make k index the deepest non-null offest + 1 */
3601    for (k = depth; k > 1 && !offsets[k-1]; k--)
3602        ;
3603    partial = ext4_get_branch(inode, k, offsets, chain, &err);
3604    /* Writer: pointers */
3605    if (!partial)
3606        partial = chain + k-1;
3607    /*
3608     * If the branch acquired continuation since we've looked at it -
3609     * fine, it should all survive and (new) top doesn't belong to us.
3610     */
3611    if (!partial->key && *partial->p)
3612        /* Writer: end */
3613        goto no_top;
3614    for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
3615        ;
3616    /*
3617     * OK, we've found the last block that must survive. The rest of our
3618     * branch should be detached before unlocking. However, if that rest
3619     * of branch is all ours and does not grow immediately from the inode
3620     * it's easier to cheat and just decrement partial->p.
3621     */
3622    if (p == chain + k - 1 && p > chain) {
3623        p->p--;
3624    } else {
3625        *top = *p->p;
3626        /* Nope, don't do this in ext4. Must leave the tree intact */
3627#if 0
3628        *p->p = 0;
3629#endif
3630    }
3631    /* Writer: end */
3632
3633    while (partial > p) {
3634        brelse(partial->bh);
3635        partial--;
3636    }
3637no_top:
3638    return partial;
3639}
3640
3641/*
3642 * Zero a number of block pointers in either an inode or an indirect block.
3643 * If we restart the transaction we must again get write access to the
3644 * indirect block for further modification.
3645 *
3646 * We release `count' blocks on disk, but (last - first) may be greater
3647 * than `count' because there can be holes in there.
3648 */
3649static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
3650                  struct buffer_head *bh,
3651                  ext4_fsblk_t block_to_free,
3652                  unsigned long count, __le32 *first,
3653                  __le32 *last)
3654{
3655    __le32 *p;
3656    if (try_to_extend_transaction(handle, inode)) {
3657        if (bh) {
3658            BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
3659            ext4_handle_dirty_metadata(handle, inode, bh);
3660        }
3661        ext4_mark_inode_dirty(handle, inode);
3662        ext4_journal_test_restart(handle, inode);
3663        if (bh) {
3664            BUFFER_TRACE(bh, "retaking write access");
3665            ext4_journal_get_write_access(handle, bh);
3666        }
3667    }
3668
3669    /*
3670     * Any buffers which are on the journal will be in memory. We
3671     * find them on the hash table so jbd2_journal_revoke() will
3672     * run jbd2_journal_forget() on them. We've already detached
3673     * each block from the file, so bforget() in
3674     * jbd2_journal_forget() should be safe.
3675     *
3676     * AKPM: turn on bforget in jbd2_journal_forget()!!!
3677     */
3678    for (p = first; p < last; p++) {
3679        u32 nr = le32_to_cpu(*p);
3680        if (nr) {
3681            struct buffer_head *tbh;
3682
3683            *p = 0;
3684            tbh = sb_find_get_block(inode->i_sb, nr);
3685            ext4_forget(handle, 0, inode, tbh, nr);
3686        }
3687    }
3688
3689    ext4_free_blocks(handle, inode, block_to_free, count, 0);
3690}
3691
3692/**
3693 * ext4_free_data - free a list of data blocks
3694 * @handle: handle for this transaction
3695 * @inode: inode we are dealing with
3696 * @this_bh: indirect buffer_head which contains *@first and *@last
3697 * @first: array of block numbers
3698 * @last: points immediately past the end of array
3699 *
3700 * We are freeing all blocks refered from that array (numbers are stored as
3701 * little-endian 32-bit) and updating @inode->i_blocks appropriately.
3702 *
3703 * We accumulate contiguous runs of blocks to free. Conveniently, if these
3704 * blocks are contiguous then releasing them at one time will only affect one
3705 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
3706 * actually use a lot of journal space.
3707 *
3708 * @this_bh will be %NULL if @first and @last point into the inode's direct
3709 * block pointers.
3710 */
3711static void ext4_free_data(handle_t *handle, struct inode *inode,
3712               struct buffer_head *this_bh,
3713               __le32 *first, __le32 *last)
3714{
3715    ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */
3716    unsigned long count = 0; /* Number of blocks in the run */
3717    __le32 *block_to_free_p = NULL; /* Pointer into inode/ind
3718                           corresponding to
3719                           block_to_free */
3720    ext4_fsblk_t nr; /* Current block # */
3721    __le32 *p; /* Pointer into inode/ind
3722                           for current block */
3723    int err;
3724
3725    if (this_bh) { /* For indirect block */
3726        BUFFER_TRACE(this_bh, "get_write_access");
3727        err = ext4_journal_get_write_access(handle, this_bh);
3728        /* Important: if we can't update the indirect pointers
3729         * to the blocks, we can't free them. */
3730        if (err)
3731            return;
3732    }
3733
3734    for (p = first; p < last; p++) {
3735        nr = le32_to_cpu(*p);
3736        if (nr) {
3737            /* accumulate blocks to free if they're contiguous */
3738            if (count == 0) {
3739                block_to_free = nr;
3740                block_to_free_p = p;
3741                count = 1;
3742            } else if (nr == block_to_free + count) {
3743                count++;
3744            } else {
3745                ext4_clear_blocks(handle, inode, this_bh,
3746                          block_to_free,
3747                          count, block_to_free_p, p);
3748                block_to_free = nr;
3749                block_to_free_p = p;
3750                count = 1;
3751            }
3752        }
3753    }
3754
3755    if (count > 0)
3756        ext4_clear_blocks(handle, inode, this_bh, block_to_free,
3757                  count, block_to_free_p, p);
3758
3759    if (this_bh) {
3760        BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
3761
3762        /*
3763         * The buffer head should have an attached journal head at this
3764         * point. However, if the data is corrupted and an indirect
3765         * block pointed to itself, it would have been detached when
3766         * the block was cleared. Check for this instead of OOPSing.
3767         */
3768        if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
3769            ext4_handle_dirty_metadata(handle, inode, this_bh);
3770        else
3771            ext4_error(inode->i_sb, __func__,
3772                   "circular indirect block detected, "
3773                   "inode=%lu, block=%llu",
3774                   inode->i_ino,
3775                   (unsigned long long) this_bh->b_blocknr);
3776    }
3777}
3778
3779/**
3780 * ext4_free_branches - free an array of branches
3781 * @handle: JBD handle for this transaction
3782 * @inode: inode we are dealing with
3783 * @parent_bh: the buffer_head which contains *@first and *@last
3784 * @first: array of block numbers
3785 * @last: pointer immediately past the end of array
3786 * @depth: depth of the branches to free
3787 *
3788 * We are freeing all blocks refered from these branches (numbers are
3789 * stored as little-endian 32-bit) and updating @inode->i_blocks
3790 * appropriately.
3791 */
3792static void ext4_free_branches(handle_t *handle, struct inode *inode,
3793                   struct buffer_head *parent_bh,
3794                   __le32 *first, __le32 *last, int depth)
3795{
3796    ext4_fsblk_t nr;
3797    __le32 *p;
3798
3799    if (ext4_handle_is_aborted(handle))
3800        return;
3801
3802    if (depth--) {
3803        struct buffer_head *bh;
3804        int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
3805        p = last;
3806        while (--p >= first) {
3807            nr = le32_to_cpu(*p);
3808            if (!nr)
3809                continue; /* A hole */
3810
3811            /* Go read the buffer for the next level down */
3812            bh = sb_bread(inode->i_sb, nr);
3813
3814            /*
3815             * A read failure? Report error and clear slot
3816             * (should be rare).
3817             */
3818            if (!bh) {
3819                ext4_error(inode->i_sb, "ext4_free_branches",
3820                       "Read failure, inode=%lu, block=%llu",
3821                       inode->i_ino, nr);
3822                continue;
3823            }
3824
3825            /* This zaps the entire block. Bottom up. */
3826            BUFFER_TRACE(bh, "free child branches");
3827            ext4_free_branches(handle, inode, bh,
3828                    (__le32 *) bh->b_data,
3829                    (__le32 *) bh->b_data + addr_per_block,
3830                    depth);
3831
3832            /*
3833             * We've probably journalled the indirect block several
3834             * times during the truncate. But it's no longer
3835             * needed and we now drop it from the transaction via
3836             * jbd2_journal_revoke().
3837             *
3838             * That's easy if it's exclusively part of this
3839             * transaction. But if it's part of the committing
3840             * transaction then jbd2_journal_forget() will simply
3841             * brelse() it. That means that if the underlying
3842             * block is reallocated in ext4_get_block(),
3843             * unmap_underlying_metadata() will find this block
3844             * and will try to get rid of it. damn, damn.
3845             *
3846             * If this block has already been committed to the
3847             * journal, a revoke record will be written. And
3848             * revoke records must be emitted *before* clearing
3849             * this block's bit in the bitmaps.
3850             */
3851            ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
3852
3853            /*
3854             * Everything below this this pointer has been
3855             * released. Now let this top-of-subtree go.
3856             *
3857             * We want the freeing of this indirect block to be
3858             * atomic in the journal with the updating of the
3859             * bitmap block which owns it. So make some room in
3860             * the journal.
3861             *
3862             * We zero the parent pointer *after* freeing its
3863             * pointee in the bitmaps, so if extend_transaction()
3864             * for some reason fails to put the bitmap changes and
3865             * the release into the same transaction, recovery
3866             * will merely complain about releasing a free block,
3867             * rather than leaking blocks.
3868             */
3869            if (ext4_handle_is_aborted(handle))
3870                return;
3871            if (try_to_extend_transaction(handle, inode)) {
3872                ext4_mark_inode_dirty(handle, inode);
3873                ext4_journal_test_restart(handle, inode);
3874            }
3875
3876            ext4_free_blocks(handle, inode, nr, 1, 1);
3877
3878            if (parent_bh) {
3879                /*
3880                 * The block which we have just freed is
3881                 * pointed to by an indirect block: journal it
3882                 */
3883                BUFFER_TRACE(parent_bh, "get_write_access");
3884                if (!ext4_journal_get_write_access(handle,
3885                                   parent_bh)){
3886                    *p = 0;
3887                    BUFFER_TRACE(parent_bh,
3888                    "call ext4_handle_dirty_metadata");
3889                    ext4_handle_dirty_metadata(handle,
3890                                   inode,
3891                                   parent_bh);
3892                }
3893            }
3894        }
3895    } else {
3896        /* We have reached the bottom of the tree. */
3897        BUFFER_TRACE(parent_bh, "free data blocks");
3898        ext4_free_data(handle, inode, parent_bh, first, last);
3899    }
3900}
3901
3902int ext4_can_truncate(struct inode *inode)
3903{
3904    if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
3905        return 0;
3906    if (S_ISREG(inode->i_mode))
3907        return 1;
3908    if (S_ISDIR(inode->i_mode))
3909        return 1;
3910    if (S_ISLNK(inode->i_mode))
3911        return !ext4_inode_is_fast_symlink(inode);
3912    return 0;
3913}
3914
3915/*
3916 * ext4_truncate()
3917 *
3918 * We block out ext4_get_block() block instantiations across the entire
3919 * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3920 * simultaneously on behalf of the same inode.
3921 *
3922 * As we work through the truncate and commmit bits of it to the journal there
3923 * is one core, guiding principle: the file's tree must always be consistent on
3924 * disk. We must be able to restart the truncate after a crash.
3925 *
3926 * The file's tree may be transiently inconsistent in memory (although it
3927 * probably isn't), but whenever we close off and commit a journal transaction,
3928 * the contents of (the filesystem + the journal) must be consistent and
3929 * restartable. It's pretty simple, really: bottom up, right to left (although
3930 * left-to-right works OK too).
3931 *
3932 * Note that at recovery time, journal replay occurs *before* the restart of
3933 * truncate against the orphan inode list.
3934 *
3935 * The committed inode has the new, desired i_size (which is the same as
3936 * i_disksize in this case). After a crash, ext4_orphan_cleanup() will see
3937 * that this inode's truncate did not complete and it will again call
3938 * ext4_truncate() to have another go. So there will be instantiated blocks
3939 * to the right of the truncation point in a crashed ext4 filesystem. But
3940 * that's fine - as long as they are linked from the inode, the post-crash
3941 * ext4_truncate() run will find them and release them.
3942 */
3943void ext4_truncate(struct inode *inode)
3944{
3945    handle_t *handle;
3946    struct ext4_inode_info *ei = EXT4_I(inode);
3947    __le32 *i_data = ei->i_data;
3948    int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
3949    struct address_space *mapping = inode->i_mapping;
3950    ext4_lblk_t offsets[4];
3951    Indirect chain[4];
3952    Indirect *partial;
3953    __le32 nr = 0;
3954    int n;
3955    ext4_lblk_t last_block;
3956    unsigned blocksize = inode->i_sb->s_blocksize;
3957
3958    if (!ext4_can_truncate(inode))
3959        return;
3960
3961    if (ei->i_disksize && inode->i_size == 0 &&
3962        !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
3963        ei->i_state |= EXT4_STATE_DA_ALLOC_CLOSE;
3964
3965    if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
3966        ext4_ext_truncate(inode);
3967        return;
3968    }
3969
3970    handle = start_transaction(inode);
3971    if (IS_ERR(handle))
3972        return; /* AKPM: return what? */
3973
3974    last_block = (inode->i_size + blocksize-1)
3975                    >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
3976
3977    if (inode->i_size & (blocksize - 1))
3978        if (ext4_block_truncate_page(handle, mapping, inode->i_size))
3979            goto out_stop;
3980
3981    n = ext4_block_to_path(inode, last_block, offsets, NULL);
3982    if (n == 0)
3983        goto out_stop; /* error */
3984
3985    /*
3986     * OK. This truncate is going to happen. We add the inode to the
3987     * orphan list, so that if this truncate spans multiple transactions,
3988     * and we crash, we will resume the truncate when the filesystem
3989     * recovers. It also marks the inode dirty, to catch the new size.
3990     *
3991     * Implication: the file must always be in a sane, consistent
3992     * truncatable state while each transaction commits.
3993     */
3994    if (ext4_orphan_add(handle, inode))
3995        goto out_stop;
3996
3997    /*
3998     * From here we block out all ext4_get_block() callers who want to
3999     * modify the block allocation tree.
4000     */
4001    down_write(&ei->i_data_sem);
4002
4003    ext4_discard_preallocations(inode);
4004
4005    /*
4006     * The orphan list entry will now protect us from any crash which
4007     * occurs before the truncate completes, so it is now safe to propagate
4008     * the new, shorter inode size (held for now in i_size) into the
4009     * on-disk inode. We do this via i_disksize, which is the value which
4010     * ext4 *really* writes onto the disk inode.
4011     */
4012    ei->i_disksize = inode->i_size;
4013
4014    if (n == 1) { /* direct blocks */
4015        ext4_free_data(handle, inode, NULL, i_data+offsets[0],
4016                   i_data + EXT4_NDIR_BLOCKS);
4017        goto do_indirects;
4018    }
4019
4020    partial = ext4_find_shared(inode, n, offsets, chain, &nr);
4021    /* Kill the top of shared branch (not detached) */
4022    if (nr) {
4023        if (partial == chain) {
4024            /* Shared branch grows from the inode */
4025            ext4_free_branches(handle, inode, NULL,
4026                       &nr, &nr+1, (chain+n-1) - partial);
4027            *partial->p = 0;
4028            /*
4029             * We mark the inode dirty prior to restart,
4030             * and prior to stop. No need for it here.
4031             */
4032        } else {
4033            /* Shared branch grows from an indirect block */
4034            BUFFER_TRACE(partial->bh, "get_write_access");
4035            ext4_free_branches(handle, inode, partial->bh,
4036                    partial->p,
4037                    partial->p+1, (chain+n-1) - partial);
4038        }
4039    }
4040    /* Clear the ends of indirect blocks on the shared branch */
4041    while (partial > chain) {
4042        ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
4043                   (__le32*)partial->bh->b_data+addr_per_block,
4044                   (chain+n-1) - partial);
4045        BUFFER_TRACE(partial->bh, "call brelse");
4046        brelse(partial->bh);
4047        partial--;
4048    }
4049do_indirects:
4050    /* Kill the remaining (whole) subtrees */
4051    switch (offsets[0]) {
4052    default:
4053        nr = i_data[EXT4_IND_BLOCK];
4054        if (nr) {
4055            ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
4056            i_data[EXT4_IND_BLOCK] = 0;
4057        }
4058    case EXT4_IND_BLOCK:
4059        nr = i_data[EXT4_DIND_BLOCK];
4060        if (nr) {
4061            ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
4062            i_data[EXT4_DIND_BLOCK] = 0;
4063        }
4064    case EXT4_DIND_BLOCK:
4065        nr = i_data[EXT4_TIND_BLOCK];
4066        if (nr) {
4067            ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
4068            i_data[EXT4_TIND_BLOCK] = 0;
4069        }
4070    case EXT4_TIND_BLOCK:
4071        ;
4072    }
4073
4074    up_write(&ei->i_data_sem);
4075    inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4076    ext4_mark_inode_dirty(handle, inode);
4077
4078    /*
4079     * In a multi-transaction truncate, we only make the final transaction
4080     * synchronous
4081     */
4082    if (IS_SYNC(inode))
4083        ext4_handle_sync(handle);
4084out_stop:
4085    /*
4086     * If this was a simple ftruncate(), and the file will remain alive
4087     * then we need to clear up the orphan record which we created above.
4088     * However, if this was a real unlink then we were called by
4089     * ext4_delete_inode(), and we allow that function to clean up the
4090     * orphan info for us.
4091     */
4092    if (inode->i_nlink)
4093        ext4_orphan_del(handle, inode);
4094
4095    ext4_journal_stop(handle);
4096}
4097
4098/*
4099 * ext4_get_inode_loc returns with an extra refcount against the inode's
4100 * underlying buffer_head on success. If 'in_mem' is true, we have all
4101 * data in memory that is needed to recreate the on-disk version of this
4102 * inode.
4103 */
4104static int __ext4_get_inode_loc(struct inode *inode,
4105                struct ext4_iloc *iloc, int in_mem)
4106{
4107    struct ext4_group_desc *gdp;
4108    struct buffer_head *bh;
4109    struct super_block *sb = inode->i_sb;
4110    ext4_fsblk_t block;
4111    int inodes_per_block, inode_offset;
4112
4113    iloc->bh = NULL;
4114    if (!ext4_valid_inum(sb, inode->i_ino))
4115        return -EIO;
4116
4117    iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4118    gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4119    if (!gdp)
4120        return -EIO;
4121
4122    /*
4123     * Figure out the offset within the block group inode table
4124     */
4125    inodes_per_block = (EXT4_BLOCK_SIZE(sb) / EXT4_INODE_SIZE(sb));
4126    inode_offset = ((inode->i_ino - 1) %
4127            EXT4_INODES_PER_GROUP(sb));
4128    block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4129    iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4130
4131    bh = sb_getblk(sb, block);
4132    if (!bh) {
4133        ext4_error(sb, "ext4_get_inode_loc", "unable to read "
4134               "inode block - inode=%lu, block=%llu",
4135               inode->i_ino, block);
4136        return -EIO;
4137    }
4138    if (!buffer_uptodate(bh)) {
4139        lock_buffer(bh);
4140
4141        /*
4142         * If the buffer has the write error flag, we have failed
4143         * to write out another inode in the same block. In this
4144         * case, we don't have to read the block because we may
4145         * read the old inode data successfully.
4146         */
4147        if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4148            set_buffer_uptodate(bh);
4149
4150        if (buffer_uptodate(bh)) {
4151            /* someone brought it uptodate while we waited */
4152            unlock_buffer(bh);
4153            goto has_buffer;
4154        }
4155
4156        /*
4157         * If we have all information of the inode in memory and this
4158         * is the only valid inode in the block, we need not read the
4159         * block.
4160         */
4161        if (in_mem) {
4162            struct buffer_head *bitmap_bh;
4163            int i, start;
4164
4165            start = inode_offset & ~(inodes_per_block - 1);
4166
4167            /* Is the inode bitmap in cache? */
4168            bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4169            if (!bitmap_bh)
4170                goto make_io;
4171
4172            /*
4173             * If the inode bitmap isn't in cache then the
4174             * optimisation may end up performing two reads instead
4175             * of one, so skip it.
4176             */
4177            if (!buffer_uptodate(bitmap_bh)) {
4178                brelse(bitmap_bh);
4179                goto make_io;
4180            }
4181            for (i = start; i < start + inodes_per_block; i++) {
4182                if (i == inode_offset)
4183                    continue;
4184                if (ext4_test_bit(i, bitmap_bh->b_data))
4185                    break;
4186            }
4187            brelse(bitmap_bh);
4188            if (i == start + inodes_per_block) {
4189                /* all other inodes are free, so skip I/O */
4190                memset(bh->b_data, 0, bh->b_size);
4191                set_buffer_uptodate(bh);
4192                unlock_buffer(bh);
4193                goto has_buffer;
4194            }
4195        }
4196
4197make_io:
4198        /*
4199         * If we need to do any I/O, try to pre-readahead extra
4200         * blocks from the inode table.
4201         */
4202        if (EXT4_SB(sb)->s_inode_readahead_blks) {
4203            ext4_fsblk_t b, end, table;
4204            unsigned num;
4205
4206            table = ext4_inode_table(sb, gdp);
4207            /* s_inode_readahead_blks is always a power of 2 */
4208            b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1);
4209            if (table > b)
4210                b = table;
4211            end = b + EXT4_SB(sb)->s_inode_readahead_blks;
4212            num = EXT4_INODES_PER_GROUP(sb);
4213            if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4214                       EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
4215                num -= ext4_itable_unused_count(sb, gdp);
4216            table += num / inodes_per_block;
4217            if (end > table)
4218                end = table;
4219            while (b <= end)
4220                sb_breadahead(sb, b++);
4221        }
4222
4223        /*
4224         * There are other valid inodes in the buffer, this inode
4225         * has in-inode xattrs, or we don't have this inode in memory.
4226         * Read the block from disk.
4227         */
4228        get_bh(bh);
4229        bh->b_end_io = end_buffer_read_sync;
4230        submit_bh(READ_META, bh);
4231        wait_on_buffer(bh);
4232        if (!buffer_uptodate(bh)) {
4233            ext4_error(sb, __func__,
4234                   "unable to read inode block - inode=%lu, "
4235                   "block=%llu", inode->i_ino, block);
4236            brelse(bh);
4237            return -EIO;
4238        }
4239    }
4240has_buffer:
4241    iloc->bh = bh;
4242    return 0;
4243}
4244
4245int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4246{
4247    /* We have all inode data except xattrs in memory here. */
4248    return __ext4_get_inode_loc(inode, iloc,
4249        !(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
4250}
4251
4252void ext4_set_inode_flags(struct inode *inode)
4253{
4254    unsigned int flags = EXT4_I(inode)->i_flags;
4255
4256    inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
4257    if (flags & EXT4_SYNC_FL)
4258        inode->i_flags |= S_SYNC;
4259    if (flags & EXT4_APPEND_FL)
4260        inode->i_flags |= S_APPEND;
4261    if (flags & EXT4_IMMUTABLE_FL)
4262        inode->i_flags |= S_IMMUTABLE;
4263    if (flags & EXT4_NOATIME_FL)
4264        inode->i_flags |= S_NOATIME;
4265    if (flags & EXT4_DIRSYNC_FL)
4266        inode->i_flags |= S_DIRSYNC;
4267}
4268
4269/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
4270void ext4_get_inode_flags(struct ext4_inode_info *ei)
4271{
4272    unsigned int flags = ei->vfs_inode.i_flags;
4273
4274    ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
4275            EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
4276    if (flags & S_SYNC)
4277        ei->i_flags |= EXT4_SYNC_FL;
4278    if (flags & S_APPEND)
4279        ei->i_flags |= EXT4_APPEND_FL;
4280    if (flags & S_IMMUTABLE)
4281        ei->i_flags |= EXT4_IMMUTABLE_FL;
4282    if (flags & S_NOATIME)
4283        ei->i_flags |= EXT4_NOATIME_FL;
4284    if (flags & S_DIRSYNC)
4285        ei->i_flags |= EXT4_DIRSYNC_FL;
4286}
4287
4288static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4289                  struct ext4_inode_info *ei)
4290{
4291    blkcnt_t i_blocks ;
4292    struct inode *inode = &(ei->vfs_inode);
4293    struct super_block *sb = inode->i_sb;
4294
4295    if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
4296                EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
4297        /* we are using combined 48 bit field */
4298        i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4299                    le32_to_cpu(raw_inode->i_blocks_lo);
4300        if (ei->i_flags & EXT4_HUGE_FILE_FL) {
4301            /* i_blocks represent file system block size */
4302            return i_blocks << (inode->i_blkbits - 9);
4303        } else {
4304            return i_blocks;
4305        }
4306    } else {
4307        return le32_to_cpu(raw_inode->i_blocks_lo);
4308    }
4309}
4310
4311struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
4312{
4313    struct ext4_iloc iloc;
4314    struct ext4_inode *raw_inode;
4315    struct ext4_inode_info *ei;
4316    struct buffer_head *bh;
4317    struct inode *inode;
4318    long ret;
4319    int block;
4320
4321    inode = iget_locked(sb, ino);
4322    if (!inode)
4323        return ERR_PTR(-ENOMEM);
4324    if (!(inode->i_state & I_NEW))
4325        return inode;
4326
4327    ei = EXT4_I(inode);
4328
4329    ret = __ext4_get_inode_loc(inode, &iloc, 0);
4330    if (ret < 0)
4331        goto bad_inode;
4332    bh = iloc.bh;
4333    raw_inode = ext4_raw_inode(&iloc);
4334    inode->i_mode = le16_to_cpu(raw_inode->i_mode);
4335    inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
4336    inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
4337    if (!(test_opt(inode->i_sb, NO_UID32))) {
4338        inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
4339        inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
4340    }
4341    inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
4342
4343    ei->i_state = 0;
4344    ei->i_dir_start_lookup = 0;
4345    ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
4346    /* We now have enough fields to check if the inode was active or not.
4347     * This is needed because nfsd might try to access dead inodes
4348     * the test is that same one that e2fsck uses
4349     * NeilBrown 1999oct15
4350     */
4351    if (inode->i_nlink == 0) {
4352        if (inode->i_mode == 0 ||
4353            !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
4354            /* this inode is deleted */
4355            brelse(bh);
4356            ret = -ESTALE;
4357            goto bad_inode;
4358        }
4359        /* The only unlinked inodes we let through here have
4360         * valid i_mode and are being read by the orphan
4361         * recovery code: that's fine, we're about to complete
4362         * the process of deleting those. */
4363    }
4364    ei->i_flags = le32_to_cpu(raw_inode->i_flags);
4365    inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
4366    ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
4367    if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT))
4368        ei->i_file_acl |=
4369            ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
4370    inode->i_size = ext4_isize(raw_inode);
4371    ei->i_disksize = inode->i_size;
4372    inode->i_generation = le32_to_cpu(raw_inode->i_generation);
4373    ei->i_block_group = iloc.block_group;
4374    ei->i_last_alloc_group = ~0;
4375    /*
4376     * NOTE! The in-memory inode i_data array is in little-endian order
4377     * even on big-endian machines: we do NOT byteswap the block numbers!
4378     */
4379    for (block = 0; block < EXT4_N_BLOCKS; block++)
4380        ei->i_data[block] = raw_inode->i_block[block];
4381    INIT_LIST_HEAD(&ei->i_orphan);
4382
4383    if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4384        ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
4385        if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
4386            EXT4_INODE_SIZE(inode->i_sb)) {
4387            brelse(bh);
4388            ret = -EIO;
4389            goto bad_inode;
4390        }
4391        if (ei->i_extra_isize == 0) {
4392            /* The extra space is currently unused. Use it. */
4393            ei->i_extra_isize = sizeof(struct ext4_inode) -
4394                        EXT4_GOOD_OLD_INODE_SIZE;
4395        } else {
4396            __le32 *magic = (void *)raw_inode +
4397                    EXT4_GOOD_OLD_INODE_SIZE +
4398                    ei->i_extra_isize;
4399            if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
4400                ei->i_state |= EXT4_STATE_XATTR;
4401        }
4402    } else
4403        ei->i_extra_isize = 0;
4404
4405    EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
4406    EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
4407    EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
4408    EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
4409
4410    inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
4411    if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4412        if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4413            inode->i_version |=
4414            (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
4415    }
4416
4417    ret = 0;
4418    if (ei->i_file_acl &&
4419        ((ei->i_file_acl <
4420          (le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) +
4421           EXT4_SB(sb)->s_gdb_count)) ||
4422         (ei->i_file_acl >= ext4_blocks_count(EXT4_SB(sb)->s_es)))) {
4423        ext4_error(sb, __func__,
4424               "bad extended attribute block %llu in inode #%lu",
4425               ei->i_file_acl, inode->i_ino);
4426        ret = -EIO;
4427        goto bad_inode;
4428    } else if (ei->i_flags & EXT4_EXTENTS_FL) {
4429        if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4430            (S_ISLNK(inode->i_mode) &&
4431             !ext4_inode_is_fast_symlink(inode)))
4432            /* Validate extent which is part of inode */
4433            ret = ext4_ext_check_inode(inode);
4434    } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4435           (S_ISLNK(inode->i_mode) &&
4436            !ext4_inode_is_fast_symlink(inode))) {
4437        /* Validate block references which are part of inode */
4438        ret = ext4_check_inode_blockref(inode);
4439    }
4440    if (ret) {
4441        brelse(bh);
4442        goto bad_inode;
4443    }
4444
4445    if (S_ISREG(inode->i_mode)) {
4446        inode->i_op = &ext4_file_inode_operations;
4447        inode->i_fop = &ext4_file_operations;
4448        ext4_set_aops(inode);
4449    } else if (S_ISDIR(inode->i_mode)) {
4450        inode->i_op = &ext4_dir_inode_operations;
4451        inode->i_fop = &ext4_dir_operations;
4452    } else if (S_ISLNK(inode->i_mode)) {
4453        if (ext4_inode_is_fast_symlink(inode)) {
4454            inode->i_op = &ext4_fast_symlink_inode_operations;
4455            nd_terminate_link(ei->i_data, inode->i_size,
4456                sizeof(ei->i_data) - 1);
4457        } else {
4458            inode->i_op = &ext4_symlink_inode_operations;
4459            ext4_set_aops(inode);
4460        }
4461    } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
4462          S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
4463        inode->i_op = &ext4_special_inode_operations;
4464        if (raw_inode->i_block[0])
4465            init_special_inode(inode, inode->i_mode,
4466               old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
4467        else
4468            init_special_inode(inode, inode->i_mode,
4469               new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
4470    } else {
4471        brelse(bh);
4472        ret = -EIO;
4473        ext4_error(inode->i_sb, __func__,
4474               "bogus i_mode (%o) for inode=%lu",
4475               inode->i_mode, inode->i_ino);
4476        goto bad_inode;
4477    }
4478    brelse(iloc.bh);
4479    ext4_set_inode_flags(inode);
4480    unlock_new_inode(inode);
4481    return inode;
4482
4483bad_inode:
4484    iget_failed(inode);
4485    return ERR_PTR(ret);
4486}
4487
4488static int ext4_inode_blocks_set(handle_t *handle,
4489                struct ext4_inode *raw_inode,
4490                struct ext4_inode_info *ei)
4491{
4492    struct inode *inode = &(ei->vfs_inode);
4493    u64 i_blocks = inode->i_blocks;
4494    struct super_block *sb = inode->i_sb;
4495
4496    if (i_blocks <= ~0U) {
4497        /*
4498         * i_blocks can be represnted in a 32 bit variable
4499         * as multiple of 512 bytes
4500         */
4501        raw_inode->i_blocks_lo = cpu_to_le32(i_blocks);
4502        raw_inode->i_blocks_high = 0;
4503        ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4504        return 0;
4505    }
4506    if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
4507        return -EFBIG;
4508
4509    if (i_blocks <= 0xffffffffffffULL) {
4510        /*
4511         * i_blocks can be represented in a 48 bit variable
4512         * as multiple of 512 bytes
4513         */
4514        raw_inode->i_blocks_lo = cpu_to_le32(i_blocks);
4515        raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4516        ei->i_flags &= ~EXT4_HUGE_FILE_FL;
4517    } else {
4518        ei->i_flags |= EXT4_HUGE_FILE_FL;
4519        /* i_block is stored in file system block size */
4520        i_blocks = i_blocks >> (inode->i_blkbits - 9);
4521        raw_inode->i_blocks_lo = cpu_to_le32(i_blocks);
4522        raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4523    }
4524    return 0;
4525}
4526
4527/*
4528 * Post the struct inode info into an on-disk inode location in the
4529 * buffer-cache. This gobbles the caller's reference to the
4530 * buffer_head in the inode location struct.
4531 *
4532 * The caller must have write access to iloc->bh.
4533 */
4534static int ext4_do_update_inode(handle_t *handle,
4535                struct inode *inode,
4536                struct ext4_iloc *iloc)
4537{
4538    struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
4539    struct ext4_inode_info *ei = EXT4_I(inode);
4540    struct buffer_head *bh = iloc->bh;
4541    int err = 0, rc, block;
4542
4543    /* For fields not not tracking in the in-memory inode,
4544     * initialise them to zero for new inodes. */
4545    if (ei->i_state & EXT4_STATE_NEW)
4546        memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4547
4548    ext4_get_inode_flags(ei);
4549    raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4550    if (!(test_opt(inode->i_sb, NO_UID32))) {
4551        raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
4552        raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
4553/*
4554 * Fix up interoperability with old kernels. Otherwise, old inodes get
4555 * re-used with the upper 16 bits of the uid/gid intact
4556 */
4557        if (!ei->i_dtime) {
4558            raw_inode->i_uid_high =
4559                cpu_to_le16(high_16_bits(inode->i_uid));
4560            raw_inode->i_gid_high =
4561                cpu_to_le16(high_16_bits(inode->i_gid));
4562        } else {
4563            raw_inode->i_uid_high = 0;
4564            raw_inode->i_gid_high = 0;
4565        }
4566    } else {
4567        raw_inode->i_uid_low =
4568            cpu_to_le16(fs_high2lowuid(inode->i_uid));
4569        raw_inode->i_gid_low =
4570            cpu_to_le16(fs_high2lowgid(inode->i_gid));
4571        raw_inode->i_uid_high = 0;
4572        raw_inode->i_gid_high = 0;
4573    }
4574    raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
4575
4576    EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
4577    EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
4578    EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
4579    EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
4580
4581    if (ext4_inode_blocks_set(handle, raw_inode, ei))
4582        goto out_brelse;
4583    raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
4584    /* clear the migrate flag in the raw_inode */
4585    raw_inode->i_flags = cpu_to_le32(ei->i_flags & ~EXT4_EXT_MIGRATE);
4586    if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
4587        cpu_to_le32(EXT4_OS_HURD))
4588        raw_inode->i_file_acl_high =
4589            cpu_to_le16(ei->i_file_acl >> 32);
4590    raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
4591    ext4_isize_set(raw_inode, ei->i_disksize);
4592    if (ei->i_disksize > 0x7fffffffULL) {
4593        struct super_block *sb = inode->i_sb;
4594        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
4595                EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
4596                EXT4_SB(sb)->s_es->s_rev_level ==
4597                cpu_to_le32(EXT4_GOOD_OLD_REV)) {
4598            /* If this is the first large file
4599             * created, add a flag to the superblock.
4600             */
4601            err = ext4_journal_get_write_access(handle,
4602                    EXT4_SB(sb)->s_sbh);
4603            if (err)
4604                goto out_brelse;
4605            ext4_update_dynamic_rev(sb);
4606            EXT4_SET_RO_COMPAT_FEATURE(sb,
4607                    EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
4608            sb->s_dirt = 1;
4609            ext4_handle_sync(handle);
4610            err = ext4_handle_dirty_metadata(handle, inode,
4611                    EXT4_SB(sb)->s_sbh);
4612        }
4613    }
4614    raw_inode->i_generation = cpu_to_le32(inode->i_generation);
4615    if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
4616        if (old_valid_dev(inode->i_rdev)) {
4617            raw_inode->i_block[0] =
4618                cpu_to_le32(old_encode_dev(inode->i_rdev));
4619            raw_inode->i_block[1] = 0;
4620        } else {
4621            raw_inode->i_block[0] = 0;
4622            raw_inode->i_block[1] =
4623                cpu_to_le32(new_encode_dev(inode->i_rdev));
4624            raw_inode->i_block[2] = 0;
4625        }
4626    } else
4627        for (block = 0; block < EXT4_N_BLOCKS; block++)
4628            raw_inode->i_block[block] = ei->i_data[block];
4629
4630    raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
4631    if (ei->i_extra_isize) {
4632        if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4633            raw_inode->i_version_hi =
4634            cpu_to_le32(inode->i_version >> 32);
4635        raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
4636    }
4637
4638    BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
4639    rc = ext4_handle_dirty_metadata(handle, inode, bh);
4640    if (!err)
4641        err = rc;
4642    ei->i_state &= ~EXT4_STATE_NEW;
4643
4644out_brelse:
4645    brelse(bh);
4646    ext4_std_error(inode->i_sb, err);
4647    return err;
4648}
4649
4650/*
4651 * ext4_write_inode()
4652 *
4653 * We are called from a few places:
4654 *
4655 * - Within generic_file_write() for O_SYNC files.
4656 * Here, there will be no transaction running. We wait for any running
4657 * trasnaction to commit.
4658 *
4659 * - Within sys_sync(), kupdate and such.
4660 * We wait on commit, if tol to.
4661 *
4662 * - Within prune_icache() (PF_MEMALLOC == true)
4663 * Here we simply return. We can't afford to block kswapd on the
4664 * journal commit.
4665 *
4666 * In all cases it is actually safe for us to return without doing anything,
4667 * because the inode has been copied into a raw inode buffer in
4668 * ext4_mark_inode_dirty(). This is a correctness thing for O_SYNC and for
4669 * knfsd.
4670 *
4671 * Note that we are absolutely dependent upon all inode dirtiers doing the
4672 * right thing: they *must* call mark_inode_dirty() after dirtying info in
4673 * which we are interested.
4674 *
4675 * It would be a bug for them to not do this. The code:
4676 *
4677 * mark_inode_dirty(inode)
4678 * stuff();
4679 * inode->i_size = expr;
4680 *
4681 * is in error because a kswapd-driven write_inode() could occur while
4682 * `stuff()' is running, and the new i_size will be lost. Plus the inode
4683 * will no longer be on the superblock's dirty inode list.
4684 */
4685int ext4_write_inode(struct inode *inode, int wait)
4686{
4687    if (current->flags & PF_MEMALLOC)
4688        return 0;
4689
4690    if (ext4_journal_current_handle()) {
4691        jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
4692        dump_stack();
4693        return -EIO;
4694    }
4695
4696    if (!wait)
4697        return 0;
4698
4699    return ext4_force_commit(inode->i_sb);
4700}
4701
4702/*
4703 * ext4_setattr()
4704 *
4705 * Called from notify_change.
4706 *
4707 * We want to trap VFS attempts to truncate the file as soon as
4708 * possible. In particular, we want to make sure that when the VFS
4709 * shrinks i_size, we put the inode on the orphan list and modify
4710 * i_disksize immediately, so that during the subsequent flushing of
4711 * dirty pages and freeing of disk blocks, we can guarantee that any
4712 * commit will leave the blocks being flushed in an unused state on
4713 * disk. (On recovery, the inode will get truncated and the blocks will
4714 * be freed, so we have a strong guarantee that no future commit will
4715 * leave these blocks visible to the user.)
4716 *
4717 * Another thing we have to assure is that if we are in ordered mode
4718 * and inode is still attached to the committing transaction, we must
4719 * we start writeout of all the dirty pages which are being truncated.
4720 * This way we are sure that all the data written in the previous
4721 * transaction are already on disk (truncate waits for pages under
4722 * writeback).
4723 *
4724 * Called with inode->i_mutex down.
4725 */
4726int ext4_setattr(struct dentry *dentry, struct iattr *attr)
4727{
4728    struct inode *inode = dentry->d_inode;
4729    int error, rc = 0;
4730    const unsigned int ia_valid = attr->ia_valid;
4731
4732    error = inode_change_ok(inode, attr);
4733    if (error)
4734        return error;
4735
4736    if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
4737        (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
4738        handle_t *handle;
4739
4740        /* (user+group)*(old+new) structure, inode write (sb,
4741         * inode block, ? - but truncate inode update has it) */
4742        handle = ext4_journal_start(inode, 2*(EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)+
4743                    EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
4744        if (IS_ERR(handle)) {
4745            error = PTR_ERR(handle);
4746            goto err_out;
4747        }
4748        error = vfs_dq_transfer(inode, attr) ? -EDQUOT : 0;
4749        if (error) {
4750            ext4_journal_stop(handle);
4751            return error;
4752        }
4753        /* Update corresponding info in inode so that everything is in
4754         * one transaction */
4755        if (attr->ia_valid & ATTR_UID)
4756            inode->i_uid = attr->ia_uid;
4757        if (attr->ia_valid & ATTR_GID)
4758            inode->i_gid = attr->ia_gid;
4759        error = ext4_mark_inode_dirty(handle, inode);
4760        ext4_journal_stop(handle);
4761    }
4762
4763    if (attr->ia_valid & ATTR_SIZE) {
4764        if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
4765            struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4766
4767            if (attr->ia_size > sbi->s_bitmap_maxbytes) {
4768                error = -EFBIG;
4769                goto err_out;
4770            }
4771        }
4772    }
4773
4774    if (S_ISREG(inode->i_mode) &&
4775        attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
4776        handle_t *handle;
4777
4778        handle = ext4_journal_start(inode, 3);
4779        if (IS_ERR(handle)) {
4780            error = PTR_ERR(handle);
4781            goto err_out;
4782        }
4783
4784        error = ext4_orphan_add(handle, inode);
4785        EXT4_I(inode)->i_disksize = attr->ia_size;
4786        rc = ext4_mark_inode_dirty(handle, inode);
4787        if (!error)
4788            error = rc;
4789        ext4_journal_stop(handle);
4790
4791        if (ext4_should_order_data(inode)) {
4792            error = ext4_begin_ordered_truncate(inode,
4793                                attr->ia_size);
4794            if (error) {
4795                /* Do as much error cleanup as possible */
4796                handle = ext4_journal_start(inode, 3);
4797                if (IS_ERR(handle)) {
4798                    ext4_orphan_del(NULL, inode);
4799                    goto err_out;
4800                }
4801                ext4_orphan_del(handle, inode);
4802                ext4_journal_stop(handle);
4803                goto err_out;
4804            }
4805        }
4806    }
4807
4808    rc = inode_setattr(inode, attr);
4809
4810    /* If inode_setattr's call to ext4_truncate failed to get a
4811     * transaction handle at all, we need to clean up the in-core
4812     * orphan list manually. */
4813    if (inode->i_nlink)
4814        ext4_orphan_del(NULL, inode);
4815
4816    if (!rc && (ia_valid & ATTR_MODE))
4817        rc = ext4_acl_chmod(inode);
4818
4819err_out:
4820    ext4_std_error(inode->i_sb, error);
4821    if (!error)
4822        error = rc;
4823    return error;
4824}
4825
4826int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
4827         struct kstat *stat)
4828{
4829    struct inode *inode;
4830    unsigned long delalloc_blocks;
4831
4832    inode = dentry->d_inode;
4833    generic_fillattr(inode, stat);
4834
4835    /*
4836     * We can't update i_blocks if the block allocation is delayed
4837     * otherwise in the case of system crash before the real block
4838     * allocation is done, we will have i_blocks inconsistent with
4839     * on-disk file blocks.
4840     * We always keep i_blocks updated together with real
4841     * allocation. But to not confuse with user, stat
4842     * will return the blocks that include the delayed allocation
4843     * blocks for this file.
4844     */
4845    spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
4846    delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks;
4847    spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
4848
4849    stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
4850    return 0;
4851}
4852
4853static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks,
4854                      int chunk)
4855{
4856    int indirects;
4857
4858    /* if nrblocks are contiguous */
4859    if (chunk) {
4860        /*
4861         * With N contiguous data blocks, it need at most
4862         * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
4863         * 2 dindirect blocks
4864         * 1 tindirect block
4865         */
4866        indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
4867        return indirects + 3;
4868    }
4869    /*
4870     * if nrblocks are not contiguous, worse case, each block touch
4871     * a indirect block, and each indirect block touch a double indirect
4872     * block, plus a triple indirect block
4873     */
4874    indirects = nrblocks * 2 + 1;
4875    return indirects;
4876}
4877
4878static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
4879{
4880    if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
4881        return ext4_indirect_trans_blocks(inode, nrblocks, chunk);
4882    return ext4_ext_index_trans_blocks(inode, nrblocks, chunk);
4883}
4884
4885/*
4886 * Account for index blocks, block groups bitmaps and block group
4887 * descriptor blocks if modify datablocks and index blocks
4888 * worse case, the indexs blocks spread over different block groups
4889 *
4890 * If datablocks are discontiguous, they are possible to spread over
4891 * different block groups too. If they are contiugous, with flexbg,
4892 * they could still across block group boundary.
4893 *
4894 * Also account for superblock, inode, quota and xattr blocks
4895 */
4896int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
4897{
4898    ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
4899    int gdpblocks;
4900    int idxblocks;
4901    int ret = 0;
4902
4903    /*
4904     * How many index blocks need to touch to modify nrblocks?
4905     * The "Chunk" flag indicating whether the nrblocks is
4906     * physically contiguous on disk
4907     *
4908     * For Direct IO and fallocate, they calls get_block to allocate
4909     * one single extent at a time, so they could set the "Chunk" flag
4910     */
4911    idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk);
4912
4913    ret = idxblocks;
4914
4915    /*
4916     * Now let's see how many group bitmaps and group descriptors need
4917     * to account
4918     */
4919    groups = idxblocks;
4920    if (chunk)
4921        groups += 1;
4922    else
4923        groups += nrblocks;
4924
4925    gdpblocks = groups;
4926    if (groups > ngroups)
4927        groups = ngroups;
4928    if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
4929        gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
4930
4931    /* bitmaps and block group descriptor blocks */
4932    ret += groups + gdpblocks;
4933
4934    /* Blocks for super block, inode, quota and xattr blocks */
4935    ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
4936
4937    return ret;
4938}
4939
4940/*
4941 * Calulate the total number of credits to reserve to fit
4942 * the modification of a single pages into a single transaction,
4943 * which may include multiple chunks of block allocations.
4944 *
4945 * This could be called via ext4_write_begin()
4946 *
4947 * We need to consider the worse case, when
4948 * one new block per extent.
4949 */
4950int ext4_writepage_trans_blocks(struct inode *inode)
4951{
4952    int bpp = ext4_journal_blocks_per_page(inode);
4953    int ret;
4954
4955    ret = ext4_meta_trans_blocks(inode, bpp, 0);
4956
4957    /* Account for data blocks for journalled mode */
4958    if (ext4_should_journal_data(inode))
4959        ret += bpp;
4960    return ret;
4961}
4962
4963/*
4964 * Calculate the journal credits for a chunk of data modification.
4965 *
4966 * This is called from DIO, fallocate or whoever calling
4967 * ext4_get_blocks() to map/allocate a chunk of contigous disk blocks.
4968 *
4969 * journal buffers for data blocks are not included here, as DIO
4970 * and fallocate do no need to journal data buffers.
4971 */
4972int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
4973{
4974    return ext4_meta_trans_blocks(inode, nrblocks, 1);
4975}
4976
4977/*
4978 * The caller must have previously called ext4_reserve_inode_write().
4979 * Give this, we know that the caller already has write access to iloc->bh.
4980 */
4981int ext4_mark_iloc_dirty(handle_t *handle,
4982             struct inode *inode, struct ext4_iloc *iloc)
4983{
4984    int err = 0;
4985
4986    if (test_opt(inode->i_sb, I_VERSION))
4987        inode_inc_iversion(inode);
4988
4989    /* the do_update_inode consumes one bh->b_count */
4990    get_bh(iloc->bh);
4991
4992    /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
4993    err = ext4_do_update_inode(handle, inode, iloc);
4994    put_bh(iloc->bh);
4995    return err;
4996}
4997
4998/*
4999 * On success, We end up with an outstanding reference count against
5000 * iloc->bh. This _must_ be cleaned up later.
5001 */
5002
5003int
5004ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
5005             struct ext4_iloc *iloc)
5006{
5007    int err;
5008
5009    err = ext4_get_inode_loc(inode, iloc);
5010    if (!err) {
5011        BUFFER_TRACE(iloc->bh, "get_write_access");
5012        err = ext4_journal_get_write_access(handle, iloc->bh);
5013        if (err) {
5014            brelse(iloc->bh);
5015            iloc->bh = NULL;
5016        }
5017    }
5018    ext4_std_error(inode->i_sb, err);
5019    return err;
5020}
5021
5022/*
5023 * Expand an inode by new_extra_isize bytes.
5024 * Returns 0 on success or negative error number on failure.
5025 */
5026static int ext4_expand_extra_isize(struct inode *inode,
5027                   unsigned int new_extra_isize,
5028                   struct ext4_iloc iloc,
5029                   handle_t *handle)
5030{
5031    struct ext4_inode *raw_inode;
5032    struct ext4_xattr_ibody_header *header;
5033    struct ext4_xattr_entry *entry;
5034
5035    if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
5036        return 0;
5037
5038    raw_inode = ext4_raw_inode(&iloc);
5039
5040    header = IHDR(inode, raw_inode);
5041    entry = IFIRST(header);
5042
5043    /* No extended attributes present */
5044    if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR) ||
5045        header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
5046        memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
5047            new_extra_isize);
5048        EXT4_I(inode)->i_extra_isize = new_extra_isize;
5049        return 0;
5050    }
5051
5052    /* try to expand with EAs present */
5053    return ext4_expand_extra_isize_ea(inode, new_extra_isize,
5054                      raw_inode, handle);
5055}
5056
5057/*
5058 * What we do here is to mark the in-core inode as clean with respect to inode
5059 * dirtiness (it may still be data-dirty).
5060 * This means that the in-core inode may be reaped by prune_icache
5061 * without having to perform any I/O. This is a very good thing,
5062 * because *any* task may call prune_icache - even ones which
5063 * have a transaction open against a different journal.
5064 *
5065 * Is this cheating? Not really. Sure, we haven't written the
5066 * inode out, but prune_icache isn't a user-visible syncing function.
5067 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
5068 * we start and wait on commits.
5069 *
5070 * Is this efficient/effective? Well, we're being nice to the system
5071 * by cleaning up our inodes proactively so they can be reaped
5072 * without I/O. But we are potentially leaving up to five seconds'
5073 * worth of inodes floating about which prune_icache wants us to
5074 * write out. One way to fix that would be to get prune_icache()
5075 * to do a write_super() to free up some memory. It has the desired
5076 * effect.
5077 */
5078int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
5079{
5080    struct ext4_iloc iloc;
5081    struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5082    static unsigned int mnt_count;
5083    int err, ret;
5084
5085    might_sleep();
5086    err = ext4_reserve_inode_write(handle, inode, &iloc);
5087    if (ext4_handle_valid(handle) &&
5088        EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
5089        !(EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND)) {
5090        /*
5091         * We need extra buffer credits since we may write into EA block
5092         * with this same handle. If journal_extend fails, then it will
5093         * only result in a minor loss of functionality for that inode.
5094         * If this is felt to be critical, then e2fsck should be run to
5095         * force a large enough s_min_extra_isize.
5096         */
5097        if ((jbd2_journal_extend(handle,
5098                 EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
5099            ret = ext4_expand_extra_isize(inode,
5100                              sbi->s_want_extra_isize,
5101                              iloc, handle);
5102            if (ret) {
5103                EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
5104                if (mnt_count !=
5105                    le16_to_cpu(sbi->s_es->s_mnt_count)) {
5106                    ext4_warning(inode->i_sb, __func__,
5107                    "Unable to expand inode %lu. Delete"
5108                    " some EAs or run e2fsck.",
5109                    inode->i_ino);
5110                    mnt_count =
5111                      le16_to_cpu(sbi->s_es->s_mnt_count);
5112                }
5113            }
5114        }
5115    }
5116    if (!err)
5117        err = ext4_mark_iloc_dirty(handle, inode, &iloc);
5118    return err;
5119}
5120
5121/*
5122 * ext4_dirty_inode() is called from __mark_inode_dirty()
5123 *
5124 * We're really interested in the case where a file is being extended.
5125 * i_size has been changed by generic_commit_write() and we thus need
5126 * to include the updated inode in the current transaction.
5127 *
5128 * Also, vfs_dq_alloc_block() will always dirty the inode when blocks
5129 * are allocated to the file.
5130 *
5131 * If the inode is marked synchronous, we don't honour that here - doing
5132 * so would cause a commit on atime updates, which we don't bother doing.
5133 * We handle synchronous inodes at the highest possible level.
5134 */
5135void ext4_dirty_inode(struct inode *inode)
5136{
5137    handle_t *current_handle = ext4_journal_current_handle();
5138    handle_t *handle;
5139
5140    if (!ext4_handle_valid(current_handle)) {
5141        ext4_mark_inode_dirty(current_handle, inode);
5142        return;
5143    }
5144
5145    handle = ext4_journal_start(inode, 2);
5146    if (IS_ERR(handle))
5147        goto out;
5148    if (current_handle &&
5149        current_handle->h_transaction != handle->h_transaction) {
5150        /* This task has a transaction open against a different fs */
5151        printk(KERN_EMERG "%s: transactions do not match!\n",
5152               __func__);
5153    } else {
5154        jbd_debug(5, "marking dirty. outer handle=%p\n",
5155                current_handle);
5156        ext4_mark_inode_dirty(handle, inode);
5157    }
5158    ext4_journal_stop(handle);
5159out:
5160    return;
5161}
5162
5163#if 0
5164/*
5165 * Bind an inode's backing buffer_head into this transaction, to prevent
5166 * it from being flushed to disk early. Unlike
5167 * ext4_reserve_inode_write, this leaves behind no bh reference and
5168 * returns no iloc structure, so the caller needs to repeat the iloc
5169 * lookup to mark the inode dirty later.
5170 */
5171static int ext4_pin_inode(handle_t *handle, struct inode *inode)
5172{
5173    struct ext4_iloc iloc;
5174
5175    int err = 0;
5176    if (handle) {
5177        err = ext4_get_inode_loc(inode, &iloc);
5178        if (!err) {
5179            BUFFER_TRACE(iloc.bh, "get_write_access");
5180            err = jbd2_journal_get_write_access(handle, iloc.bh);
5181            if (!err)
5182                err = ext4_handle_dirty_metadata(handle,
5183                                 inode,
5184                                 iloc.bh);
5185            brelse(iloc.bh);
5186        }
5187    }
5188    ext4_std_error(inode->i_sb, err);
5189    return err;
5190}
5191#endif
5192
5193int ext4_change_inode_journal_flag(struct inode *inode, int val)
5194{
5195    journal_t *journal;
5196    handle_t *handle;
5197    int err;
5198
5199    /*
5200     * We have to be very careful here: changing a data block's
5201     * journaling status dynamically is dangerous. If we write a
5202     * data block to the journal, change the status and then delete
5203     * that block, we risk forgetting to revoke the old log record
5204     * from the journal and so a subsequent replay can corrupt data.
5205     * So, first we make sure that the journal is empty and that
5206     * nobody is changing anything.
5207     */
5208
5209    journal = EXT4_JOURNAL(inode);
5210    if (!journal)
5211        return 0;
5212    if (is_journal_aborted(journal))
5213        return -EROFS;
5214
5215    jbd2_journal_lock_updates(journal);
5216    jbd2_journal_flush(journal);
5217
5218    /*
5219     * OK, there are no updates running now, and all cached data is
5220     * synced to disk. We are now in a completely consistent state
5221     * which doesn't have anything in the journal, and we know that
5222     * no filesystem updates are running, so it is safe to modify
5223     * the inode's in-core data-journaling state flag now.
5224     */
5225
5226    if (val)
5227        EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL;
5228    else
5229        EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL;
5230    ext4_set_aops(inode);
5231
5232    jbd2_journal_unlock_updates(journal);
5233
5234    /* Finally we can mark the inode as dirty. */
5235
5236    handle = ext4_journal_start(inode, 1);
5237    if (IS_ERR(handle))
5238        return PTR_ERR(handle);
5239
5240    err = ext4_mark_inode_dirty(handle, inode);
5241    ext4_handle_sync(handle);
5242    ext4_journal_stop(handle);
5243    ext4_std_error(inode->i_sb, err);
5244
5245    return err;
5246}
5247
5248static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
5249{
5250    return !buffer_mapped(bh);
5251}
5252
5253int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
5254{
5255    struct page *page = vmf->page;
5256    loff_t size;
5257    unsigned long len;
5258    int ret = -EINVAL;
5259    void *fsdata;
5260    struct file *file = vma->vm_file;
5261    struct inode *inode = file->f_path.dentry->d_inode;
5262    struct address_space *mapping = inode->i_mapping;
5263
5264    /*
5265     * Get i_alloc_sem to stop truncates messing with the inode. We cannot
5266     * get i_mutex because we are already holding mmap_sem.
5267     */
5268    down_read(&inode->i_alloc_sem);
5269    size = i_size_read(inode);
5270    if (page->mapping != mapping || size <= page_offset(page)
5271        || !PageUptodate(page)) {
5272        /* page got truncated from under us? */
5273        goto out_unlock;
5274    }
5275    ret = 0;
5276    if (PageMappedToDisk(page))
5277        goto out_unlock;
5278
5279    if (page->index == size >> PAGE_CACHE_SHIFT)
5280        len = size & ~PAGE_CACHE_MASK;
5281    else
5282        len = PAGE_CACHE_SIZE;
5283
5284    if (page_has_buffers(page)) {
5285        /* return if we have all the buffers mapped */
5286        if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
5287                       ext4_bh_unmapped))
5288            goto out_unlock;
5289    }
5290    /*
5291     * OK, we need to fill the hole... Do write_begin write_end
5292     * to do block allocation/reservation.We are not holding
5293     * inode.i__mutex here. That allow * parallel write_begin,
5294     * write_end call. lock_page prevent this from happening
5295     * on the same page though
5296     */
5297    ret = mapping->a_ops->write_begin(file, mapping, page_offset(page),
5298            len, AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
5299    if (ret < 0)
5300        goto out_unlock;
5301    ret = mapping->a_ops->write_end(file, mapping, page_offset(page),
5302            len, len, page, fsdata);
5303    if (ret < 0)
5304        goto out_unlock;
5305    ret = 0;
5306out_unlock:
5307    if (ret)
5308        ret = VM_FAULT_SIGBUS;
5309    up_read(&inode->i_alloc_sem);
5310    return ret;
5311}
5312

Archive Download this file



interactive