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Root/fs/ext3/inode.c

1	/*
2	* linux/fs/ext3/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 ext3_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/ext3_jbd.h>
29	#include <linux/jbd.h>
30	#include <linux/highuid.h>
31	#include <linux/pagemap.h>
32	#include <linux/quotaops.h>
33	#include <linux/string.h>
34	#include <linux/buffer_head.h>
35	#include <linux/writeback.h>
36	#include <linux/mpage.h>
37	#include <linux/uio.h>
38	#include <linux/bio.h>
39	#include <linux/fiemap.h>
40	#include <linux/namei.h>
41	#include "xattr.h"
42	#include "acl.h"
43
44	static int ext3_writepage_trans_blocks(struct inode *inode);
45
46	/*
47	* Test whether an inode is a fast symlink.
48	*/
49	static int ext3_inode_is_fast_symlink(struct inode *inode)
50	{
51	int ea_blocks = EXT3_I(inode)->i_file_acl ?
52	(inode->i_sb->s_blocksize >> 9) : 0;
53
54	return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
55	}
56
57	/*
58	* The ext3 forget function must perform a revoke if we are freeing data
59	* which has been journaled. Metadata (eg. indirect blocks) must be
60	* revoked in all cases.
61	*
62	* "bh" may be NULL: a metadata block may have been freed from memory
63	* but there may still be a record of it in the journal, and that record
64	* still needs to be revoked.
65	*/
66	int ext3_forget(handle_t handle, int is_metadata, struct inode inode,
67	struct buffer_head *bh, ext3_fsblk_t blocknr)
68	{
69	int err;
70
71	might_sleep();
72
73	BUFFER_TRACE(bh, "enter");
74
75	jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
76	"data mode %lx\n",
77	bh, is_metadata, inode->i_mode,
78	test_opt(inode->i_sb, DATA_FLAGS));
79
80	/* Never use the revoke function if we are doing full data
81	* journaling: there is no need to, and a V1 superblock won't
82	* support it. Otherwise, only skip the revoke on un-journaled
83	* data blocks. */
84
85	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA \|\|
86	(!is_metadata && !ext3_should_journal_data(inode))) {
87	if (bh) {
88	BUFFER_TRACE(bh, "call journal_forget");
89	return ext3_journal_forget(handle, bh);
90	}
91	return 0;
92	}
93
94	/*
95	* data!=journal && (is_metadata \|\| should_journal_data(inode))
96	*/
97	BUFFER_TRACE(bh, "call ext3_journal_revoke");
98	err = ext3_journal_revoke(handle, blocknr, bh);
99	if (err)
100	ext3_abort(inode->i_sb, __func__,
101	"error %d when attempting revoke", err);
102	BUFFER_TRACE(bh, "exit");
103	return err;
104	}
105
106	/*
107	* Work out how many blocks we need to proceed with the next chunk of a
108	* truncate transaction.
109	*/
110	static unsigned long blocks_for_truncate(struct inode *inode)
111	{
112	unsigned long needed;
113
114	needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
115
116	/* Give ourselves just enough room to cope with inodes in which
117	* i_blocks is corrupt: we've seen disk corruptions in the past
118	* which resulted in random data in an inode which looked enough
119	* like a regular file for ext3 to try to delete it. Things
120	* will go a bit crazy if that happens, but at least we should
121	* try not to panic the whole kernel. */
122	if (needed < 2)
123	needed = 2;
124
125	/* But we need to bound the transaction so we don't overflow the
126	* journal. */
127	if (needed > EXT3_MAX_TRANS_DATA)
128	needed = EXT3_MAX_TRANS_DATA;
129
130	return EXT3_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
131	}
132
133	/*
134	* Truncate transactions can be complex and absolutely huge. So we need to
135	* be able to restart the transaction at a conventient checkpoint to make
136	* sure we don't overflow the journal.
137	*
138	* start_transaction gets us a new handle for a truncate transaction,
139	* and extend_transaction tries to extend the existing one a bit. If
140	* extend fails, we need to propagate the failure up and restart the
141	* transaction in the top-level truncate loop. --sct
142	*/
143	static handle_t start_transaction(struct inode inode)
144	{
145	handle_t *result;
146
147	result = ext3_journal_start(inode, blocks_for_truncate(inode));
148	if (!IS_ERR(result))
149	return result;
150
151	ext3_std_error(inode->i_sb, PTR_ERR(result));
152	return result;
153	}
154
155	/*
156	* Try to extend this transaction for the purposes of truncation.
157	*
158	* Returns 0 if we managed to create more room. If we can't create more
159	* room, and the transaction must be restarted we return 1.
160	*/
161	static int try_to_extend_transaction(handle_t handle, struct inode inode)
162	{
163	if (handle->h_buffer_credits > EXT3_RESERVE_TRANS_BLOCKS)
164	return 0;
165	if (!ext3_journal_extend(handle, blocks_for_truncate(inode)))
166	return 0;
167	return 1;
168	}
169
170	/*
171	* Restart the transaction associated with *handle. This does a commit,
172	* so before we call here everything must be consistently dirtied against
173	* this transaction.
174	*/
175	static int truncate_restart_transaction(handle_t handle, struct inode inode)
176	{
177	int ret;
178
179	jbd_debug(2, "restarting handle %p\n", handle);
180	/*
181	* Drop truncate_mutex to avoid deadlock with ext3_get_blocks_handle
182	* At this moment, get_block can be called only for blocks inside
183	* i_size since page cache has been already dropped and writes are
184	* blocked by i_mutex. So we can safely drop the truncate_mutex.
185	*/
186	mutex_unlock(&EXT3_I(inode)->truncate_mutex);
187	ret = ext3_journal_restart(handle, blocks_for_truncate(inode));
188	mutex_lock(&EXT3_I(inode)->truncate_mutex);
189	return ret;
190	}
191
192	/*
193	* Called at inode eviction from icache
194	*/
195	void ext3_evict_inode (struct inode *inode)
196	{
197	struct ext3_block_alloc_info *rsv;
198	handle_t *handle;
199	int want_delete = 0;
200
201	if (!inode->i_nlink && !is_bad_inode(inode)) {
202	dquot_initialize(inode);
203	want_delete = 1;
204	}
205
206	truncate_inode_pages(&inode->i_data, 0);
207
208	ext3_discard_reservation(inode);
209	rsv = EXT3_I(inode)->i_block_alloc_info;
210	EXT3_I(inode)->i_block_alloc_info = NULL;
211	if (unlikely(rsv))
212	kfree(rsv);
213
214	if (!want_delete)
215	goto no_delete;
216
217	handle = start_transaction(inode);
218	if (IS_ERR(handle)) {
219	/*
220	* If we're going to skip the normal cleanup, we still need to
221	* make sure that the in-core orphan linked list is properly
222	* cleaned up.
223	*/
224	ext3_orphan_del(NULL, inode);
225	goto no_delete;
226	}
227
228	if (IS_SYNC(inode))
229	handle->h_sync = 1;
230	inode->i_size = 0;
231	if (inode->i_blocks)
232	ext3_truncate(inode);
233	/*
234	* Kill off the orphan record which ext3_truncate created.
235	* AKPM: I think this can be inside the above `if'.
236	* Note that ext3_orphan_del() has to be able to cope with the
237	* deletion of a non-existent orphan - this is because we don't
238	* know if ext3_truncate() actually created an orphan record.
239	* (Well, we could do this if we need to, but heck - it works)
240	*/
241	ext3_orphan_del(handle, inode);
242	EXT3_I(inode)->i_dtime = get_seconds();
243
244	/*
245	* One subtle ordering requirement: if anything has gone wrong
246	* (transaction abort, IO errors, whatever), then we can still
247	* do these next steps (the fs will already have been marked as
248	* having errors), but we can't free the inode if the mark_dirty
249	* fails.
250	*/
251	if (ext3_mark_inode_dirty(handle, inode)) {
252	/* If that failed, just dquot_drop() and be done with that */
253	dquot_drop(inode);
254	end_writeback(inode);
255	} else {
256	ext3_xattr_delete_inode(handle, inode);
257	dquot_free_inode(inode);
258	dquot_drop(inode);
259	end_writeback(inode);
260	ext3_free_inode(handle, inode);
261	}
262	ext3_journal_stop(handle);
263	return;
264	no_delete:
265	end_writeback(inode);
266	dquot_drop(inode);
267	}
268
269	typedef struct {
270	__le32 *p;
271	__le32 key;
272	struct buffer_head *bh;
273	} Indirect;
274
275	static inline void add_chain(Indirect p, struct buffer_head bh, __le32 *v)
276	{
277	p->key = *(p->p = v);
278	p->bh = bh;
279	}
280
281	static int verify_chain(Indirect from, Indirect to)
282	{
283	while (from <= to && from->key == *from->p)
284	from++;
285	return (from > to);
286	}
287
288	/**
289	* ext3_block_to_path - parse the block number into array of offsets
290	* @inode: inode in question (we are only interested in its superblock)
291	* @i_block: block number to be parsed
292	* @offsets: array to store the offsets in
293	* @boundary: set this non-zero if the referred-to block is likely to be
294	* followed (on disk) by an indirect block.
295	*
296	* To store the locations of file's data ext3 uses a data structure common
297	* for UNIX filesystems - tree of pointers anchored in the inode, with
298	* data blocks at leaves and indirect blocks in intermediate nodes.
299	* This function translates the block number into path in that tree -
300	* return value is the path length and @offsets[n] is the offset of
301	* pointer to (n+1)th node in the nth one. If @block is out of range
302	* (negative or too large) warning is printed and zero returned.
303	*
304	* Note: function doesn't find node addresses, so no IO is needed. All
305	* we need to know is the capacity of indirect blocks (taken from the
306	* inode->i_sb).
307	*/
308
309	/*
310	* Portability note: the last comparison (check that we fit into triple
311	* indirect block) is spelled differently, because otherwise on an
312	* architecture with 32-bit longs and 8Kb pages we might get into trouble
313	* if our filesystem had 8Kb blocks. We might use long long, but that would
314	* kill us on x86. Oh, well, at least the sign propagation does not matter -
315	* i_block would have to be negative in the very beginning, so we would not
316	* get there at all.
317	*/
318
319	static int ext3_block_to_path(struct inode *inode,
320	long i_block, int offsets[4], int *boundary)
321	{
322	int ptrs = EXT3_ADDR_PER_BLOCK(inode->i_sb);
323	int ptrs_bits = EXT3_ADDR_PER_BLOCK_BITS(inode->i_sb);
324	const long direct_blocks = EXT3_NDIR_BLOCKS,
325	indirect_blocks = ptrs,
326	double_blocks = (1 << (ptrs_bits * 2));
327	int n = 0;
328	int final = 0;
329
330	if (i_block < 0) {
331	ext3_warning (inode->i_sb, "ext3_block_to_path", "block < 0");
332	} else if (i_block < direct_blocks) {
333	offsets[n++] = i_block;
334	final = direct_blocks;
335	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
336	offsets[n++] = EXT3_IND_BLOCK;
337	offsets[n++] = i_block;
338	final = ptrs;
339	} else if ((i_block -= indirect_blocks) < double_blocks) {
340	offsets[n++] = EXT3_DIND_BLOCK;
341	offsets[n++] = i_block >> ptrs_bits;
342	offsets[n++] = i_block & (ptrs - 1);
343	final = ptrs;
344	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
345	offsets[n++] = EXT3_TIND_BLOCK;
346	offsets[n++] = i_block >> (ptrs_bits * 2);
347	offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
348	offsets[n++] = i_block & (ptrs - 1);
349	final = ptrs;
350	} else {
351	ext3_warning(inode->i_sb, "ext3_block_to_path", "block > big");
352	}
353	if (boundary)
354	*boundary = final - 1 - (i_block & (ptrs - 1));
355	return n;
356	}
357
358	/**
359	* ext3_get_branch - read the chain of indirect blocks leading to data
360	* @inode: inode in question
361	* @depth: depth of the chain (1 - direct pointer, etc.)
362	* @offsets: offsets of pointers in inode/indirect blocks
363	* @chain: place to store the result
364	* @err: here we store the error value
365	*
366	* Function fills the array of triples <key, p, bh> and returns %NULL
367	* if everything went OK or the pointer to the last filled triple
368	* (incomplete one) otherwise. Upon the return chain[i].key contains
369	* the number of (i+1)-th block in the chain (as it is stored in memory,
370	* i.e. little-endian 32-bit), chain[i].p contains the address of that
371	* number (it points into struct inode for i==0 and into the bh->b_data
372	* for i>0) and chain[i].bh points to the buffer_head of i-th indirect
373	* block for i>0 and NULL for i==0. In other words, it holds the block
374	* numbers of the chain, addresses they were taken from (and where we can
375	* verify that chain did not change) and buffer_heads hosting these
376	* numbers.
377	*
378	* Function stops when it stumbles upon zero pointer (absent block)
379	* (pointer to last triple returned, *@err == 0)
380	* or when it gets an IO error reading an indirect block
381	* (ditto, *@err == -EIO)
382	* or when it notices that chain had been changed while it was reading
383	* (ditto, *@err == -EAGAIN)
384	* or when it reads all @depth-1 indirect blocks successfully and finds
385	* the whole chain, all way to the data (returns %NULL, *err == 0).
386	*/
387	static Indirect ext3_get_branch(struct inode inode, int depth, int *offsets,
388	Indirect chain[4], int *err)
389	{
390	struct super_block *sb = inode->i_sb;
391	Indirect *p = chain;
392	struct buffer_head *bh;
393
394	*err = 0;
395	/* i_data is not going away, no lock needed */
396	add_chain (chain, NULL, EXT3_I(inode)->i_data + *offsets);
397	if (!p->key)
398	goto no_block;
399	while (--depth) {
400	bh = sb_bread(sb, le32_to_cpu(p->key));
401	if (!bh)
402	goto failure;
403	/* Reader: pointers */
404	if (!verify_chain(chain, p))
405	goto changed;
406	add_chain(++p, bh, (__le32)bh->b_data + ++offsets);
407	/* Reader: end */
408	if (!p->key)
409	goto no_block;
410	}
411	return NULL;
412
413	changed:
414	brelse(bh);
415	*err = -EAGAIN;
416	goto no_block;
417	failure:
418	*err = -EIO;
419	no_block:
420	return p;
421	}
422
423	/**
424	* ext3_find_near - find a place for allocation with sufficient locality
425	* @inode: owner
426	* @ind: descriptor of indirect block.
427	*
428	* This function returns the preferred place for block allocation.
429	* It is used when heuristic for sequential allocation fails.
430	* Rules are:
431	* + if there is a block to the left of our position - allocate near it.
432	* + if pointer will live in indirect block - allocate near that block.
433	* + if pointer will live in inode - allocate in the same
434	* cylinder group.
435	*
436	* In the latter case we colour the starting block by the callers PID to
437	* prevent it from clashing with concurrent allocations for a different inode
438	* in the same block group. The PID is used here so that functionally related
439	* files will be close-by on-disk.
440	*
441	* Caller must make sure that @ind is valid and will stay that way.
442	*/
443	static ext3_fsblk_t ext3_find_near(struct inode inode, Indirect ind)
444	{
445	struct ext3_inode_info *ei = EXT3_I(inode);
446	__le32 start = ind->bh ? (__le32) ind->bh->b_data : ei->i_data;
447	__le32 *p;
448	ext3_fsblk_t bg_start;
449	ext3_grpblk_t colour;
450
451	/* Try to find previous block */
452	for (p = ind->p - 1; p >= start; p--) {
453	if (*p)
454	return le32_to_cpu(*p);
455	}
456
457	/* No such thing, so let's try location of indirect block */
458	if (ind->bh)
459	return ind->bh->b_blocknr;
460
461	/*
462	* It is going to be referred to from the inode itself? OK, just put it
463	* into the same cylinder group then.
464	*/
465	bg_start = ext3_group_first_block_no(inode->i_sb, ei->i_block_group);
466	colour = (current->pid % 16) *
467	(EXT3_BLOCKS_PER_GROUP(inode->i_sb) / 16);
468	return bg_start + colour;
469	}
470
471	/**
472	* ext3_find_goal - find a preferred place for allocation.
473	* @inode: owner
474	* @block: block we want
475	* @partial: pointer to the last triple within a chain
476	*
477	* Normally this function find the preferred place for block allocation,
478	* returns it.
479	*/
480
481	static ext3_fsblk_t ext3_find_goal(struct inode *inode, long block,
482	Indirect *partial)
483	{
484	struct ext3_block_alloc_info *block_i;
485
486	block_i = EXT3_I(inode)->i_block_alloc_info;
487
488	/*
489	* try the heuristic for sequential allocation,
490	* failing that at least try to get decent locality.
491	*/
492	if (block_i && (block == block_i->last_alloc_logical_block + 1)
493	&& (block_i->last_alloc_physical_block != 0)) {
494	return block_i->last_alloc_physical_block + 1;
495	}
496
497	return ext3_find_near(inode, partial);
498	}
499
500	/**
501	* ext3_blks_to_allocate - Look up the block map and count the number
502	* of direct blocks need to be allocated for the given branch.
503	*
504	* @branch: chain of indirect blocks
505	* @k: number of blocks need for indirect blocks
506	* @blks: number of data blocks to be mapped.
507	* @blocks_to_boundary: the offset in the indirect block
508	*
509	* return the total number of blocks to be allocate, including the
510	* direct and indirect blocks.
511	*/
512	static int ext3_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
513	int blocks_to_boundary)
514	{
515	unsigned long count = 0;
516
517	/*
518	* Simple case, [t,d]Indirect block(s) has not allocated yet
519	* then it's clear blocks on that path have not allocated
520	*/
521	if (k > 0) {
522	/* right now we don't handle cross boundary allocation */
523	if (blks < blocks_to_boundary + 1)
524	count += blks;
525	else
526	count += blocks_to_boundary + 1;
527	return count;
528	}
529
530	count++;
531	while (count < blks && count <= blocks_to_boundary &&
532	le32_to_cpu(*(branch[0].p + count)) == 0) {
533	count++;
534	}
535	return count;
536	}
537
538	/**
539	* ext3_alloc_blocks - multiple allocate blocks needed for a branch
540	* @handle: handle for this transaction
541	* @inode: owner
542	* @goal: preferred place for allocation
543	* @indirect_blks: the number of blocks need to allocate for indirect
544	* blocks
545	* @blks: number of blocks need to allocated for direct blocks
546	* @new_blocks: on return it will store the new block numbers for
547	* the indirect blocks(if needed) and the first direct block,
548	* @err: here we store the error value
549	*
550	* return the number of direct blocks allocated
551	*/
552	static int ext3_alloc_blocks(handle_t handle, struct inode inode,
553	ext3_fsblk_t goal, int indirect_blks, int blks,
554	ext3_fsblk_t new_blocks[4], int *err)
555	{
556	int target, i;
557	unsigned long count = 0;
558	int index = 0;
559	ext3_fsblk_t current_block = 0;
560	int ret = 0;
561
562	/*
563	* Here we try to allocate the requested multiple blocks at once,
564	* on a best-effort basis.
565	* To build a branch, we should allocate blocks for
566	* the indirect blocks(if not allocated yet), and at least
567	* the first direct block of this branch. That's the
568	* minimum number of blocks need to allocate(required)
569	*/
570	target = blks + indirect_blks;
571
572	while (1) {
573	count = target;
574	/* allocating blocks for indirect blocks and direct blocks */
575	current_block = ext3_new_blocks(handle,inode,goal,&count,err);
576	if (*err)
577	goto failed_out;
578
579	target -= count;
580	/* allocate blocks for indirect blocks */
581	while (index < indirect_blks && count) {
582	new_blocks[index++] = current_block++;
583	count--;
584	}
585
586	if (count > 0)
587	break;
588	}
589
590	/* save the new block number for the first direct block */
591	new_blocks[index] = current_block;
592
593	/* total number of blocks allocated for direct blocks */
594	ret = count;
595	*err = 0;
596	return ret;
597	failed_out:
598	for (i = 0; i <index; i++)
599	ext3_free_blocks(handle, inode, new_blocks[i], 1);
600	return ret;
601	}
602
603	/**
604	* ext3_alloc_branch - allocate and set up a chain of blocks.
605	* @handle: handle for this transaction
606	* @inode: owner
607	* @indirect_blks: number of allocated indirect blocks
608	* @blks: number of allocated direct blocks
609	* @goal: preferred place for allocation
610	* @offsets: offsets (in the blocks) to store the pointers to next.
611	* @branch: place to store the chain in.
612	*
613	* This function allocates blocks, zeroes out all but the last one,
614	* links them into chain and (if we are synchronous) writes them to disk.
615	* In other words, it prepares a branch that can be spliced onto the
616	* inode. It stores the information about that chain in the branch[], in
617	* the same format as ext3_get_branch() would do. We are calling it after
618	* we had read the existing part of chain and partial points to the last
619	* triple of that (one with zero ->key). Upon the exit we have the same
620	* picture as after the successful ext3_get_block(), except that in one
621	* place chain is disconnected - *branch->p is still zero (we did not
622	* set the last link), but branch->key contains the number that should
623	* be placed into *branch->p to fill that gap.
624	*
625	* If allocation fails we free all blocks we've allocated (and forget
626	* their buffer_heads) and return the error value the from failed
627	* ext3_alloc_block() (normally -ENOSPC). Otherwise we set the chain
628	* as described above and return 0.
629	*/
630	static int ext3_alloc_branch(handle_t handle, struct inode inode,
631	int indirect_blks, int *blks, ext3_fsblk_t goal,
632	int offsets, Indirect branch)
633	{
634	int blocksize = inode->i_sb->s_blocksize;
635	int i, n = 0;
636	int err = 0;
637	struct buffer_head *bh;
638	int num;
639	ext3_fsblk_t new_blocks[4];
640	ext3_fsblk_t current_block;
641
642	num = ext3_alloc_blocks(handle, inode, goal, indirect_blks,
643	*blks, new_blocks, &err);
644	if (err)
645	return err;
646
647	branch[0].key = cpu_to_le32(new_blocks[0]);
648	/*
649	* metadata blocks and data blocks are allocated.
650	*/
651	for (n = 1; n <= indirect_blks; n++) {
652	/*
653	* Get buffer_head for parent block, zero it out
654	* and set the pointer to new one, then send
655	* parent to disk.
656	*/
657	bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
658	branch[n].bh = bh;
659	lock_buffer(bh);
660	BUFFER_TRACE(bh, "call get_create_access");
661	err = ext3_journal_get_create_access(handle, bh);
662	if (err) {
663	unlock_buffer(bh);
664	brelse(bh);
665	goto failed;
666	}
667
668	memset(bh->b_data, 0, blocksize);
669	branch[n].p = (__le32 *) bh->b_data + offsets[n];
670	branch[n].key = cpu_to_le32(new_blocks[n]);
671	*branch[n].p = branch[n].key;
672	if ( n == indirect_blks) {
673	current_block = new_blocks[n];
674	/*
675	* End of chain, update the last new metablock of
676	* the chain to point to the new allocated
677	* data blocks numbers
678	*/
679	for (i=1; i < num; i++)
680	*(branch[n].p + i) = cpu_to_le32(++current_block);
681	}
682	BUFFER_TRACE(bh, "marking uptodate");
683	set_buffer_uptodate(bh);
684	unlock_buffer(bh);
685
686	BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
687	err = ext3_journal_dirty_metadata(handle, bh);
688	if (err)
689	goto failed;
690	}
691	*blks = num;
692	return err;
693	failed:
694	/* Allocation failed, free what we already allocated */
695	for (i = 1; i <= n ; i++) {
696	BUFFER_TRACE(branch[i].bh, "call journal_forget");
697	ext3_journal_forget(handle, branch[i].bh);
698	}
699	for (i = 0; i <indirect_blks; i++)
700	ext3_free_blocks(handle, inode, new_blocks[i], 1);
701
702	ext3_free_blocks(handle, inode, new_blocks[i], num);
703
704	return err;
705	}
706
707	/**
708	* ext3_splice_branch - splice the allocated branch onto inode.
709	* @handle: handle for this transaction
710	* @inode: owner
711	* @block: (logical) number of block we are adding
712	* @where: location of missing link
713	* @num: number of indirect blocks we are adding
714	* @blks: number of direct blocks we are adding
715	*
716	* This function fills the missing link and does all housekeeping needed in
717	* inode (->i_blocks, etc.). In case of success we end up with the full
718	* chain to new block and return 0.
719	*/
720	static int ext3_splice_branch(handle_t handle, struct inode inode,
721	long block, Indirect *where, int num, int blks)
722	{
723	int i;
724	int err = 0;
725	struct ext3_block_alloc_info *block_i;
726	ext3_fsblk_t current_block;
727	struct ext3_inode_info *ei = EXT3_I(inode);
728
729	block_i = ei->i_block_alloc_info;
730	/*
731	* If we're splicing into a [td]indirect block (as opposed to the
732	* inode) then we need to get write access to the [td]indirect block
733	* before the splice.
734	*/
735	if (where->bh) {
736	BUFFER_TRACE(where->bh, "get_write_access");
737	err = ext3_journal_get_write_access(handle, where->bh);
738	if (err)
739	goto err_out;
740	}
741	/* That's it */
742
743	*where->p = where->key;
744
745	/*
746	* Update the host buffer_head or inode to point to more just allocated
747	* direct blocks blocks
748	*/
749	if (num == 0 && blks > 1) {
750	current_block = le32_to_cpu(where->key) + 1;
751	for (i = 1; i < blks; i++)
752	*(where->p + i ) = cpu_to_le32(current_block++);
753	}
754
755	/*
756	* update the most recently allocated logical & physical block
757	* in i_block_alloc_info, to assist find the proper goal block for next
758	* allocation
759	*/
760	if (block_i) {
761	block_i->last_alloc_logical_block = block + blks - 1;
762	block_i->last_alloc_physical_block =
763	le32_to_cpu(where[num].key) + blks - 1;
764	}
765
766	/* We are done with atomic stuff, now do the rest of housekeeping */
767
768	inode->i_ctime = CURRENT_TIME_SEC;
769	ext3_mark_inode_dirty(handle, inode);
770	/* ext3_mark_inode_dirty already updated i_sync_tid */
771	atomic_set(&ei->i_datasync_tid, handle->h_transaction->t_tid);
772
773	/* had we spliced it onto indirect block? */
774	if (where->bh) {
775	/*
776	* If we spliced it onto an indirect block, we haven't
777	* altered the inode. Note however that if it is being spliced
778	* onto an indirect block at the very end of the file (the
779	* file is growing) then we will alter the inode to reflect
780	* the new i_size. But that is not done here - it is done in
781	* generic_commit_write->__mark_inode_dirty->ext3_dirty_inode.
782	*/
783	jbd_debug(5, "splicing indirect only\n");
784	BUFFER_TRACE(where->bh, "call ext3_journal_dirty_metadata");
785	err = ext3_journal_dirty_metadata(handle, where->bh);
786	if (err)
787	goto err_out;
788	} else {
789	/*
790	* OK, we spliced it into the inode itself on a direct block.
791	* Inode was dirtied above.
792	*/
793	jbd_debug(5, "splicing direct\n");
794	}
795	return err;
796
797	err_out:
798	for (i = 1; i <= num; i++) {
799	BUFFER_TRACE(where[i].bh, "call journal_forget");
800	ext3_journal_forget(handle, where[i].bh);
801	ext3_free_blocks(handle,inode,le32_to_cpu(where[i-1].key),1);
802	}
803	ext3_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks);
804
805	return err;
806	}
807
808	/*
809	* Allocation strategy is simple: if we have to allocate something, we will
810	* have to go the whole way to leaf. So let's do it before attaching anything
811	* to tree, set linkage between the newborn blocks, write them if sync is
812	* required, recheck the path, free and repeat if check fails, otherwise
813	* set the last missing link (that will protect us from any truncate-generated
814	* removals - all blocks on the path are immune now) and possibly force the
815	* write on the parent block.
816	* That has a nice additional property: no special recovery from the failed
817	* allocations is needed - we simply release blocks and do not touch anything
818	* reachable from inode.
819	*
820	* `handle' can be NULL if create == 0.
821	*
822	* The BKL may not be held on entry here. Be sure to take it early.
823	* return > 0, # of blocks mapped or allocated.
824	* return = 0, if plain lookup failed.
825	* return < 0, error case.
826	*/
827	int ext3_get_blocks_handle(handle_t handle, struct inode inode,
828	sector_t iblock, unsigned long maxblocks,
829	struct buffer_head *bh_result,
830	int create)
831	{
832	int err = -EIO;
833	int offsets[4];
834	Indirect chain[4];
835	Indirect *partial;
836	ext3_fsblk_t goal;
837	int indirect_blks;
838	int blocks_to_boundary = 0;
839	int depth;
840	struct ext3_inode_info *ei = EXT3_I(inode);
841	int count = 0;
842	ext3_fsblk_t first_block = 0;
843
844
845	J_ASSERT(handle != NULL \|\| create == 0);
846	depth = ext3_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
847
848	if (depth == 0)
849	goto out;
850
851	partial = ext3_get_branch(inode, depth, offsets, chain, &err);
852
853	/* Simplest case - block found, no allocation needed */
854	if (!partial) {
855	first_block = le32_to_cpu(chain[depth - 1].key);
856	clear_buffer_new(bh_result);
857	count++;
858	/map more blocks/
859	while (count < maxblocks && count <= blocks_to_boundary) {
860	ext3_fsblk_t blk;
861
862	if (!verify_chain(chain, chain + depth - 1)) {
863	/*
864	* Indirect block might be removed by
865	* truncate while we were reading it.
866	* Handling of that case: forget what we've
867	* got now. Flag the err as EAGAIN, so it
868	* will reread.
869	*/
870	err = -EAGAIN;
871	count = 0;
872	break;
873	}
874	blk = le32_to_cpu(*(chain[depth-1].p + count));
875
876	if (blk == first_block + count)
877	count++;
878	else
879	break;
880	}
881	if (err != -EAGAIN)
882	goto got_it;
883	}
884
885	/* Next simple case - plain lookup or failed read of indirect block */
886	if (!create \|\| err == -EIO)
887	goto cleanup;
888
889	mutex_lock(&ei->truncate_mutex);
890
891	/*
892	* If the indirect block is missing while we are reading
893	* the chain(ext3_get_branch() returns -EAGAIN err), or
894	* if the chain has been changed after we grab the semaphore,
895	* (either because another process truncated this branch, or
896	* another get_block allocated this branch) re-grab the chain to see if
897	* the request block has been allocated or not.
898	*
899	* Since we already block the truncate/other get_block
900	* at this point, we will have the current copy of the chain when we
901	* splice the branch into the tree.
902	*/
903	if (err == -EAGAIN \|\| !verify_chain(chain, partial)) {
904	while (partial > chain) {
905	brelse(partial->bh);
906	partial--;
907	}
908	partial = ext3_get_branch(inode, depth, offsets, chain, &err);
909	if (!partial) {
910	count++;
911	mutex_unlock(&ei->truncate_mutex);
912	if (err)
913	goto cleanup;
914	clear_buffer_new(bh_result);
915	goto got_it;
916	}
917	}
918
919	/*
920	* Okay, we need to do block allocation. Lazily initialize the block
921	* allocation info here if necessary
922	*/
923	if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
924	ext3_init_block_alloc_info(inode);
925
926	goal = ext3_find_goal(inode, iblock, partial);
927
928	/* the number of blocks need to allocate for [d,t]indirect blocks */
929	indirect_blks = (chain + depth) - partial - 1;
930
931	/*
932	* Next look up the indirect map to count the totoal number of
933	* direct blocks to allocate for this branch.
934	*/
935	count = ext3_blks_to_allocate(partial, indirect_blks,
936	maxblocks, blocks_to_boundary);
937	/*
938	* Block out ext3_truncate while we alter the tree
939	*/
940	err = ext3_alloc_branch(handle, inode, indirect_blks, &count, goal,
941	offsets + (partial - chain), partial);
942
943	/*
944	* The ext3_splice_branch call will free and forget any buffers
945	* on the new chain if there is a failure, but that risks using
946	* up transaction credits, especially for bitmaps where the
947	* credits cannot be returned. Can we handle this somehow? We
948	* may need to return -EAGAIN upwards in the worst case. --sct
949	*/
950	if (!err)
951	err = ext3_splice_branch(handle, inode, iblock,
952	partial, indirect_blks, count);
953	mutex_unlock(&ei->truncate_mutex);
954	if (err)
955	goto cleanup;
956
957	set_buffer_new(bh_result);
958	got_it:
959	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
960	if (count > blocks_to_boundary)
961	set_buffer_boundary(bh_result);
962	err = count;
963	/* Clean up and exit */
964	partial = chain + depth - 1; /* the whole chain */
965	cleanup:
966	while (partial > chain) {
967	BUFFER_TRACE(partial->bh, "call brelse");
968	brelse(partial->bh);
969	partial--;
970	}
971	BUFFER_TRACE(bh_result, "returned");
972	out:
973	return err;
974	}
975
976	/* Maximum number of blocks we map for direct IO at once. */
977	#define DIO_MAX_BLOCKS 4096
978	/*
979	* Number of credits we need for writing DIO_MAX_BLOCKS:
980	* We need sb + group descriptor + bitmap + inode -> 4
981	* For B blocks with A block pointers per block we need:
982	* 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
983	* If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
984	*/
985	#define DIO_CREDITS 25
986
987	static int ext3_get_block(struct inode *inode, sector_t iblock,
988	struct buffer_head *bh_result, int create)
989	{
990	handle_t *handle = ext3_journal_current_handle();
991	int ret = 0, started = 0;
992	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
993
994	if (create && !handle) { /* Direct IO write... */
995	if (max_blocks > DIO_MAX_BLOCKS)
996	max_blocks = DIO_MAX_BLOCKS;
997	handle = ext3_journal_start(inode, DIO_CREDITS +
998	EXT3_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
999	if (IS_ERR(handle)) {
1000	ret = PTR_ERR(handle);
1001	goto out;
1002	}
1003	started = 1;
1004	}
1005
1006	ret = ext3_get_blocks_handle(handle, inode, iblock,
1007	max_blocks, bh_result, create);
1008	if (ret > 0) {
1009	bh_result->b_size = (ret << inode->i_blkbits);
1010	ret = 0;
1011	}
1012	if (started)
1013	ext3_journal_stop(handle);
1014	out:
1015	return ret;
1016	}
1017
1018	int ext3_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
1019	u64 start, u64 len)
1020	{
1021	return generic_block_fiemap(inode, fieinfo, start, len,
1022	ext3_get_block);
1023	}
1024
1025	/*
1026	* `handle' can be NULL if create is zero
1027	*/
1028	struct buffer_head ext3_getblk(handle_t handle, struct inode *inode,
1029	long block, int create, int *errp)
1030	{
1031	struct buffer_head dummy;
1032	int fatal = 0, err;
1033
1034	J_ASSERT(handle != NULL \|\| create == 0);
1035
1036	dummy.b_state = 0;
1037	dummy.b_blocknr = -1000;
1038	buffer_trace_init(&dummy.b_history);
1039	err = ext3_get_blocks_handle(handle, inode, block, 1,
1040	&dummy, create);
1041	/*
1042	* ext3_get_blocks_handle() returns number of blocks
1043	* mapped. 0 in case of a HOLE.
1044	*/
1045	if (err > 0) {
1046	if (err > 1)
1047	WARN_ON(1);
1048	err = 0;
1049	}
1050	*errp = err;
1051	if (!err && buffer_mapped(&dummy)) {
1052	struct buffer_head *bh;
1053	bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
1054	if (!bh) {
1055	*errp = -EIO;
1056	goto err;
1057	}
1058	if (buffer_new(&dummy)) {
1059	J_ASSERT(create != 0);
1060	J_ASSERT(handle != NULL);
1061
1062	/*
1063	* Now that we do not always journal data, we should
1064	* keep in mind whether this should always journal the
1065	* new buffer as metadata. For now, regular file
1066	* writes use ext3_get_block instead, so it's not a
1067	* problem.
1068	*/
1069	lock_buffer(bh);
1070	BUFFER_TRACE(bh, "call get_create_access");
1071	fatal = ext3_journal_get_create_access(handle, bh);
1072	if (!fatal && !buffer_uptodate(bh)) {
1073	memset(bh->b_data,0,inode->i_sb->s_blocksize);
1074	set_buffer_uptodate(bh);
1075	}
1076	unlock_buffer(bh);
1077	BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
1078	err = ext3_journal_dirty_metadata(handle, bh);
1079	if (!fatal)
1080	fatal = err;
1081	} else {
1082	BUFFER_TRACE(bh, "not a new buffer");
1083	}
1084	if (fatal) {
1085	*errp = fatal;
1086	brelse(bh);
1087	bh = NULL;
1088	}
1089	return bh;
1090	}
1091	err:
1092	return NULL;
1093	}
1094
1095	struct buffer_head ext3_bread(handle_t handle, struct inode *inode,
1096	int block, int create, int *err)
1097	{
1098	struct buffer_head * bh;
1099
1100	bh = ext3_getblk(handle, inode, block, create, err);
1101	if (!bh)
1102	return bh;
1103	if (buffer_uptodate(bh))
1104	return bh;
1105	ll_rw_block(READ_META, 1, &bh);
1106	wait_on_buffer(bh);
1107	if (buffer_uptodate(bh))
1108	return bh;
1109	put_bh(bh);
1110	*err = -EIO;
1111	return NULL;
1112	}
1113
1114	static int walk_page_buffers( handle_t *handle,
1115	struct buffer_head *head,
1116	unsigned from,
1117	unsigned to,
1118	int *partial,
1119	int (fn)( handle_t handle,
1120	struct buffer_head *bh))
1121	{
1122	struct buffer_head *bh;
1123	unsigned block_start, block_end;
1124	unsigned blocksize = head->b_size;
1125	int err, ret = 0;
1126	struct buffer_head *next;
1127
1128	for ( bh = head, block_start = 0;
1129	ret == 0 && (bh != head \|\| !block_start);
1130	block_start = block_end, bh = next)
1131	{
1132	next = bh->b_this_page;
1133	block_end = block_start + blocksize;
1134	if (block_end <= from \|\| block_start >= to) {
1135	if (partial && !buffer_uptodate(bh))
1136	*partial = 1;
1137	continue;
1138	}
1139	err = (*fn)(handle, bh);
1140	if (!ret)
1141	ret = err;
1142	}
1143	return ret;
1144	}
1145
1146	/*
1147	* To preserve ordering, it is essential that the hole instantiation and
1148	* the data write be encapsulated in a single transaction. We cannot
1149	* close off a transaction and start a new one between the ext3_get_block()
1150	* and the commit_write(). So doing the journal_start at the start of
1151	* prepare_write() is the right place.
1152	*
1153	* Also, this function can nest inside ext3_writepage() ->
1154	* block_write_full_page(). In that case, we know that ext3_writepage()
1155	* has generated enough buffer credits to do the whole page. So we won't
1156	* block on the journal in that case, which is good, because the caller may
1157	* be PF_MEMALLOC.
1158	*
1159	* By accident, ext3 can be reentered when a transaction is open via
1160	* quota file writes. If we were to commit the transaction while thus
1161	* reentered, there can be a deadlock - we would be holding a quota
1162	* lock, and the commit would never complete if another thread had a
1163	* transaction open and was blocking on the quota lock - a ranking
1164	* violation.
1165	*
1166	* So what we do is to rely on the fact that journal_stop/journal_start
1167	* will _not_ run commit under these circumstances because handle->h_ref
1168	* is elevated. We'll still have enough credits for the tiny quotafile
1169	* write.
1170	*/
1171	static int do_journal_get_write_access(handle_t *handle,
1172	struct buffer_head *bh)
1173	{
1174	int dirty = buffer_dirty(bh);
1175	int ret;
1176
1177	if (!buffer_mapped(bh) \|\| buffer_freed(bh))
1178	return 0;
1179	/*
1180	* __block_prepare_write() could have dirtied some buffers. Clean
1181	* the dirty bit as jbd2_journal_get_write_access() could complain
1182	* otherwise about fs integrity issues. Setting of the dirty bit
1183	* by __block_prepare_write() isn't a real problem here as we clear
1184	* the bit before releasing a page lock and thus writeback cannot
1185	* ever write the buffer.
1186	*/
1187	if (dirty)
1188	clear_buffer_dirty(bh);
1189	ret = ext3_journal_get_write_access(handle, bh);
1190	if (!ret && dirty)
1191	ret = ext3_journal_dirty_metadata(handle, bh);
1192	return ret;
1193	}
1194
1195	/*
1196	* Truncate blocks that were not used by write. We have to truncate the
1197	* pagecache as well so that corresponding buffers get properly unmapped.
1198	*/
1199	static void ext3_truncate_failed_write(struct inode *inode)
1200	{
1201	truncate_inode_pages(inode->i_mapping, inode->i_size);
1202	ext3_truncate(inode);
1203	}
1204
1205	static int ext3_write_begin(struct file file, struct address_space mapping,
1206	loff_t pos, unsigned len, unsigned flags,
1207	struct page pagep, void fsdata)
1208	{
1209	struct inode *inode = mapping->host;
1210	int ret;
1211	handle_t *handle;
1212	int retries = 0;
1213	struct page *page;
1214	pgoff_t index;
1215	unsigned from, to;
1216	/* Reserve one block more for addition to orphan list in case
1217	* we allocate blocks but write fails for some reason */
1218	int needed_blocks = ext3_writepage_trans_blocks(inode) + 1;
1219
1220	index = pos >> PAGE_CACHE_SHIFT;
1221	from = pos & (PAGE_CACHE_SIZE - 1);
1222	to = from + len;
1223
1224	retry:
1225	page = grab_cache_page_write_begin(mapping, index, flags);
1226	if (!page)
1227	return -ENOMEM;
1228	*pagep = page;
1229
1230	handle = ext3_journal_start(inode, needed_blocks);
1231	if (IS_ERR(handle)) {
1232	unlock_page(page);
1233	page_cache_release(page);
1234	ret = PTR_ERR(handle);
1235	goto out;
1236	}
1237	ret = __block_write_begin(page, pos, len, ext3_get_block);
1238	if (ret)
1239	goto write_begin_failed;
1240
1241	if (ext3_should_journal_data(inode)) {
1242	ret = walk_page_buffers(handle, page_buffers(page),
1243	from, to, NULL, do_journal_get_write_access);
1244	}
1245	write_begin_failed:
1246	if (ret) {
1247	/*
1248	* block_write_begin may have instantiated a few blocks
1249	* outside i_size. Trim these off again. Don't need
1250	* i_size_read because we hold i_mutex.
1251	*
1252	* Add inode to orphan list in case we crash before truncate
1253	* finishes. Do this only if ext3_can_truncate() agrees so
1254	* that orphan processing code is happy.
1255	*/
1256	if (pos + len > inode->i_size && ext3_can_truncate(inode))
1257	ext3_orphan_add(handle, inode);
1258	ext3_journal_stop(handle);
1259	unlock_page(page);
1260	page_cache_release(page);
1261	if (pos + len > inode->i_size)
1262	ext3_truncate_failed_write(inode);
1263	}
1264	if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
1265	goto retry;
1266	out:
1267	return ret;
1268	}
1269
1270
1271	int ext3_journal_dirty_data(handle_t handle, struct buffer_head bh)
1272	{
1273	int err = journal_dirty_data(handle, bh);
1274	if (err)
1275	ext3_journal_abort_handle(__func__, __func__,
1276	bh, handle, err);
1277	return err;
1278	}
1279
1280	/* For ordered writepage and write_end functions */
1281	static int journal_dirty_data_fn(handle_t handle, struct buffer_head bh)
1282	{
1283	/*
1284	* Write could have mapped the buffer but it didn't copy the data in
1285	* yet. So avoid filing such buffer into a transaction.
1286	*/
1287	if (buffer_mapped(bh) && buffer_uptodate(bh))
1288	return ext3_journal_dirty_data(handle, bh);
1289	return 0;
1290	}
1291
1292	/* For write_end() in data=journal mode */
1293	static int write_end_fn(handle_t handle, struct buffer_head bh)
1294	{
1295	if (!buffer_mapped(bh) \|\| buffer_freed(bh))
1296	return 0;
1297	set_buffer_uptodate(bh);
1298	return ext3_journal_dirty_metadata(handle, bh);
1299	}
1300
1301	/*
1302	* This is nasty and subtle: ext3_write_begin() could have allocated blocks
1303	* for the whole page but later we failed to copy the data in. Update inode
1304	* size according to what we managed to copy. The rest is going to be
1305	* truncated in write_end function.
1306	*/
1307	static void update_file_sizes(struct inode *inode, loff_t pos, unsigned copied)
1308	{
1309	/* What matters to us is i_disksize. We don't write i_size anywhere */
1310	if (pos + copied > inode->i_size)
1311	i_size_write(inode, pos + copied);
1312	if (pos + copied > EXT3_I(inode)->i_disksize) {
1313	EXT3_I(inode)->i_disksize = pos + copied;
1314	mark_inode_dirty(inode);
1315	}
1316	}
1317
1318	/*
1319	* We need to pick up the new inode size which generic_commit_write gave us
1320	* `file' can be NULL - eg, when called from page_symlink().
1321	*
1322	* ext3 never places buffers on inode->i_mapping->private_list. metadata
1323	* buffers are managed internally.
1324	*/
1325	static int ext3_ordered_write_end(struct file *file,
1326	struct address_space *mapping,
1327	loff_t pos, unsigned len, unsigned copied,
1328	struct page page, void fsdata)
1329	{
1330	handle_t *handle = ext3_journal_current_handle();
1331	struct inode *inode = file->f_mapping->host;
1332	unsigned from, to;
1333	int ret = 0, ret2;
1334
1335	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1336
1337	from = pos & (PAGE_CACHE_SIZE - 1);
1338	to = from + copied;
1339	ret = walk_page_buffers(handle, page_buffers(page),
1340	from, to, NULL, journal_dirty_data_fn);
1341
1342	if (ret == 0)
1343	update_file_sizes(inode, pos, copied);
1344	/*
1345	* There may be allocated blocks outside of i_size because
1346	* we failed to copy some data. Prepare for truncate.
1347	*/
1348	if (pos + len > inode->i_size && ext3_can_truncate(inode))
1349	ext3_orphan_add(handle, inode);
1350	ret2 = ext3_journal_stop(handle);
1351	if (!ret)
1352	ret = ret2;
1353	unlock_page(page);
1354	page_cache_release(page);
1355
1356	if (pos + len > inode->i_size)
1357	ext3_truncate_failed_write(inode);
1358	return ret ? ret : copied;
1359	}
1360
1361	static int ext3_writeback_write_end(struct file *file,
1362	struct address_space *mapping,
1363	loff_t pos, unsigned len, unsigned copied,
1364	struct page page, void fsdata)
1365	{
1366	handle_t *handle = ext3_journal_current_handle();
1367	struct inode *inode = file->f_mapping->host;
1368	int ret;
1369
1370	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1371	update_file_sizes(inode, pos, copied);
1372	/*
1373	* There may be allocated blocks outside of i_size because
1374	* we failed to copy some data. Prepare for truncate.
1375	*/
1376	if (pos + len > inode->i_size && ext3_can_truncate(inode))
1377	ext3_orphan_add(handle, inode);
1378	ret = ext3_journal_stop(handle);
1379	unlock_page(page);
1380	page_cache_release(page);
1381
1382	if (pos + len > inode->i_size)
1383	ext3_truncate_failed_write(inode);
1384	return ret ? ret : copied;
1385	}
1386
1387	static int ext3_journalled_write_end(struct file *file,
1388	struct address_space *mapping,
1389	loff_t pos, unsigned len, unsigned copied,
1390	struct page page, void fsdata)
1391	{
1392	handle_t *handle = ext3_journal_current_handle();
1393	struct inode *inode = mapping->host;
1394	int ret = 0, ret2;
1395	int partial = 0;
1396	unsigned from, to;
1397
1398	from = pos & (PAGE_CACHE_SIZE - 1);
1399	to = from + len;
1400
1401	if (copied < len) {
1402	if (!PageUptodate(page))
1403	copied = 0;
1404	page_zero_new_buffers(page, from + copied, to);
1405	to = from + copied;
1406	}
1407
1408	ret = walk_page_buffers(handle, page_buffers(page), from,
1409	to, &partial, write_end_fn);
1410	if (!partial)
1411	SetPageUptodate(page);
1412
1413	if (pos + copied > inode->i_size)
1414	i_size_write(inode, pos + copied);
1415	/*
1416	* There may be allocated blocks outside of i_size because
1417	* we failed to copy some data. Prepare for truncate.
1418	*/
1419	if (pos + len > inode->i_size && ext3_can_truncate(inode))
1420	ext3_orphan_add(handle, inode);
1421	ext3_set_inode_state(inode, EXT3_STATE_JDATA);
1422	if (inode->i_size > EXT3_I(inode)->i_disksize) {
1423	EXT3_I(inode)->i_disksize = inode->i_size;
1424	ret2 = ext3_mark_inode_dirty(handle, inode);
1425	if (!ret)
1426	ret = ret2;
1427	}
1428
1429	ret2 = ext3_journal_stop(handle);
1430	if (!ret)
1431	ret = ret2;
1432	unlock_page(page);
1433	page_cache_release(page);
1434
1435	if (pos + len > inode->i_size)
1436	ext3_truncate_failed_write(inode);
1437	return ret ? ret : copied;
1438	}
1439
1440	/*
1441	* bmap() is special. It gets used by applications such as lilo and by
1442	* the swapper to find the on-disk block of a specific piece of data.
1443	*
1444	* Naturally, this is dangerous if the block concerned is still in the
1445	* journal. If somebody makes a swapfile on an ext3 data-journaling
1446	* filesystem and enables swap, then they may get a nasty shock when the
1447	* data getting swapped to that swapfile suddenly gets overwritten by
1448	* the original zero's written out previously to the journal and
1449	* awaiting writeback in the kernel's buffer cache.
1450	*
1451	* So, if we see any bmap calls here on a modified, data-journaled file,
1452	* take extra steps to flush any blocks which might be in the cache.
1453	*/
1454	static sector_t ext3_bmap(struct address_space *mapping, sector_t block)
1455	{
1456	struct inode *inode = mapping->host;
1457	journal_t *journal;
1458	int err;
1459
1460	if (ext3_test_inode_state(inode, EXT3_STATE_JDATA)) {
1461	/*
1462	* This is a REALLY heavyweight approach, but the use of
1463	* bmap on dirty files is expected to be extremely rare:
1464	* only if we run lilo or swapon on a freshly made file
1465	* do we expect this to happen.
1466	*
1467	* (bmap requires CAP_SYS_RAWIO so this does not
1468	* represent an unprivileged user DOS attack --- we'd be
1469	* in trouble if mortal users could trigger this path at
1470	* will.)
1471	*
1472	* NB. EXT3_STATE_JDATA is not set on files other than
1473	* regular files. If somebody wants to bmap a directory
1474	* or symlink and gets confused because the buffer
1475	* hasn't yet been flushed to disk, they deserve
1476	* everything they get.
1477	*/
1478
1479	ext3_clear_inode_state(inode, EXT3_STATE_JDATA);
1480	journal = EXT3_JOURNAL(inode);
1481	journal_lock_updates(journal);
1482	err = journal_flush(journal);
1483	journal_unlock_updates(journal);
1484
1485	if (err)
1486	return 0;
1487	}
1488
1489	return generic_block_bmap(mapping,block,ext3_get_block);
1490	}
1491
1492	static int bget_one(handle_t handle, struct buffer_head bh)
1493	{
1494	get_bh(bh);
1495	return 0;
1496	}
1497
1498	static int bput_one(handle_t handle, struct buffer_head bh)
1499	{
1500	put_bh(bh);
1501	return 0;
1502	}
1503
1504	static int buffer_unmapped(handle_t handle, struct buffer_head bh)
1505	{
1506	return !buffer_mapped(bh);
1507	}
1508
1509	/*
1510	* Note that we always start a transaction even if we're not journalling
1511	* data. This is to preserve ordering: any hole instantiation within
1512	* __block_write_full_page -> ext3_get_block() should be journalled
1513	* along with the data so we don't crash and then get metadata which
1514	* refers to old data.
1515	*
1516	* In all journalling modes block_write_full_page() will start the I/O.
1517	*
1518	* Problem:
1519	*
1520	* ext3_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1521	* ext3_writepage()
1522	*
1523	* Similar for:
1524	*
1525	* ext3_file_write() -> generic_file_write() -> __alloc_pages() -> ...
1526	*
1527	* Same applies to ext3_get_block(). We will deadlock on various things like
1528	* lock_journal and i_truncate_mutex.
1529	*
1530	* Setting PF_MEMALLOC here doesn't work - too many internal memory
1531	* allocations fail.
1532	*
1533	* 16May01: If we're reentered then journal_current_handle() will be
1534	* non-zero. We simply return.
1535	*
1536	* 1 July 2001: @@@ FIXME:
1537	* In journalled data mode, a data buffer may be metadata against the
1538	* current transaction. But the same file is part of a shared mapping
1539	* and someone does a writepage() on it.
1540	*
1541	* We will move the buffer onto the async_data list, but after it has
1542	* been dirtied. So there's a small window where we have dirty data on
1543	* BJ_Metadata.
1544	*
1545	* Note that this only applies to the last partial page in the file. The
1546	* bit which block_write_full_page() uses prepare/commit for. (That's
1547	* broken code anyway: it's wrong for msync()).
1548	*
1549	* It's a rare case: affects the final partial page, for journalled data
1550	* where the file is subject to bith write() and writepage() in the same
1551	* transction. To fix it we'll need a custom block_write_full_page().
1552	* We'll probably need that anyway for journalling writepage() output.
1553	*
1554	* We don't honour synchronous mounts for writepage(). That would be
1555	* disastrous. Any write() or metadata operation will sync the fs for
1556	* us.
1557	*
1558	* AKPM2: if all the page's buffers are mapped to disk and !data=journal,
1559	* we don't need to open a transaction here.
1560	*/
1561	static int ext3_ordered_writepage(struct page *page,
1562	struct writeback_control *wbc)
1563	{
1564	struct inode *inode = page->mapping->host;
1565	struct buffer_head *page_bufs;
1566	handle_t *handle = NULL;
1567	int ret = 0;
1568	int err;
1569
1570	J_ASSERT(PageLocked(page));
1571	WARN_ON_ONCE(IS_RDONLY(inode));
1572
1573	/*
1574	* We give up here if we're reentered, because it might be for a
1575	* different filesystem.
1576	*/
1577	if (ext3_journal_current_handle())
1578	goto out_fail;
1579
1580	if (!page_has_buffers(page)) {
1581	create_empty_buffers(page, inode->i_sb->s_blocksize,
1582	(1 << BH_Dirty)\|(1 << BH_Uptodate));
1583	page_bufs = page_buffers(page);
1584	} else {
1585	page_bufs = page_buffers(page);
1586	if (!walk_page_buffers(NULL, page_bufs, 0, PAGE_CACHE_SIZE,
1587	NULL, buffer_unmapped)) {
1588	/* Provide NULL get_block() to catch bugs if buffers
1589	* weren't really mapped */
1590	return block_write_full_page(page, NULL, wbc);
1591	}
1592	}
1593	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
1594
1595	if (IS_ERR(handle)) {
1596	ret = PTR_ERR(handle);
1597	goto out_fail;
1598	}
1599
1600	walk_page_buffers(handle, page_bufs, 0,
1601	PAGE_CACHE_SIZE, NULL, bget_one);
1602
1603	ret = block_write_full_page(page, ext3_get_block, wbc);
1604
1605	/*
1606	* The page can become unlocked at any point now, and
1607	* truncate can then come in and change things. So we
1608	* can't touch page from now on. But page_bufs is
1609	* safe due to elevated refcount.
1610	*/
1611
1612	/*
1613	* And attach them to the current transaction. But only if
1614	* block_write_full_page() succeeded. Otherwise they are unmapped,
1615	* and generally junk.
1616	*/
1617	if (ret == 0) {
1618	err = walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE,
1619	NULL, journal_dirty_data_fn);
1620	if (!ret)
1621	ret = err;
1622	}
1623	walk_page_buffers(handle, page_bufs, 0,
1624	PAGE_CACHE_SIZE, NULL, bput_one);
1625	err = ext3_journal_stop(handle);
1626	if (!ret)
1627	ret = err;
1628	return ret;
1629
1630	out_fail:
1631	redirty_page_for_writepage(wbc, page);
1632	unlock_page(page);
1633	return ret;
1634	}
1635
1636	static int ext3_writeback_writepage(struct page *page,
1637	struct writeback_control *wbc)
1638	{
1639	struct inode *inode = page->mapping->host;
1640	handle_t *handle = NULL;
1641	int ret = 0;
1642	int err;
1643
1644	J_ASSERT(PageLocked(page));
1645	WARN_ON_ONCE(IS_RDONLY(inode));
1646
1647	if (ext3_journal_current_handle())
1648	goto out_fail;
1649
1650	if (page_has_buffers(page)) {
1651	if (!walk_page_buffers(NULL, page_buffers(page), 0,
1652	PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {
1653	/* Provide NULL get_block() to catch bugs if buffers
1654	* weren't really mapped */
1655	return block_write_full_page(page, NULL, wbc);
1656	}
1657	}
1658
1659	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
1660	if (IS_ERR(handle)) {
1661	ret = PTR_ERR(handle);
1662	goto out_fail;
1663	}
1664
1665	ret = block_write_full_page(page, ext3_get_block, wbc);
1666
1667	err = ext3_journal_stop(handle);
1668	if (!ret)
1669	ret = err;
1670	return ret;
1671
1672	out_fail:
1673	redirty_page_for_writepage(wbc, page);
1674	unlock_page(page);
1675	return ret;
1676	}
1677
1678	static int ext3_journalled_writepage(struct page *page,
1679	struct writeback_control *wbc)
1680	{
1681	struct inode *inode = page->mapping->host;
1682	handle_t *handle = NULL;
1683	int ret = 0;
1684	int err;
1685
1686	J_ASSERT(PageLocked(page));
1687	WARN_ON_ONCE(IS_RDONLY(inode));
1688
1689	if (ext3_journal_current_handle())
1690	goto no_write;
1691
1692	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
1693	if (IS_ERR(handle)) {
1694	ret = PTR_ERR(handle);
1695	goto no_write;
1696	}
1697
1698	if (!page_has_buffers(page) \|\| PageChecked(page)) {
1699	/*
1700	* It's mmapped pagecache. Add buffers and journal it. There
1701	* doesn't seem much point in redirtying the page here.
1702	*/
1703	ClearPageChecked(page);
1704	ret = __block_write_begin(page, 0, PAGE_CACHE_SIZE,
1705	ext3_get_block);
1706	if (ret != 0) {
1707	ext3_journal_stop(handle);
1708	goto out_unlock;
1709	}
1710	ret = walk_page_buffers(handle, page_buffers(page), 0,
1711	PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
1712
1713	err = walk_page_buffers(handle, page_buffers(page), 0,
1714	PAGE_CACHE_SIZE, NULL, write_end_fn);
1715	if (ret == 0)
1716	ret = err;
1717	ext3_set_inode_state(inode, EXT3_STATE_JDATA);
1718	unlock_page(page);
1719	} else {
1720	/*
1721	* It may be a page full of checkpoint-mode buffers. We don't
1722	* really know unless we go poke around in the buffer_heads.
1723	* But block_write_full_page will do the right thing.
1724	*/
1725	ret = block_write_full_page(page, ext3_get_block, wbc);
1726	}
1727	err = ext3_journal_stop(handle);
1728	if (!ret)
1729	ret = err;
1730	out:
1731	return ret;
1732
1733	no_write:
1734	redirty_page_for_writepage(wbc, page);
1735	out_unlock:
1736	unlock_page(page);
1737	goto out;
1738	}
1739
1740	static int ext3_readpage(struct file file, struct page page)
1741	{
1742	return mpage_readpage(page, ext3_get_block);
1743	}
1744
1745	static int
1746	ext3_readpages(struct file file, struct address_space mapping,
1747	struct list_head *pages, unsigned nr_pages)
1748	{
1749	return mpage_readpages(mapping, pages, nr_pages, ext3_get_block);
1750	}
1751
1752	static void ext3_invalidatepage(struct page *page, unsigned long offset)
1753	{
1754	journal_t *journal = EXT3_JOURNAL(page->mapping->host);
1755
1756	/*
1757	* If it's a full truncate we just forget about the pending dirtying
1758	*/
1759	if (offset == 0)
1760	ClearPageChecked(page);
1761
1762	journal_invalidatepage(journal, page, offset);
1763	}
1764
1765	static int ext3_releasepage(struct page *page, gfp_t wait)
1766	{
1767	journal_t *journal = EXT3_JOURNAL(page->mapping->host);
1768
1769	WARN_ON(PageChecked(page));
1770	if (!page_has_buffers(page))
1771	return 0;
1772	return journal_try_to_free_buffers(journal, page, wait);
1773	}
1774
1775	/*
1776	* If the O_DIRECT write will extend the file then add this inode to the
1777	* orphan list. So recovery will truncate it back to the original size
1778	* if the machine crashes during the write.
1779	*
1780	* If the O_DIRECT write is intantiating holes inside i_size and the machine
1781	* crashes then stale disk data _may_ be exposed inside the file. But current
1782	* VFS code falls back into buffered path in that case so we are safe.
1783	*/
1784	static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
1785	const struct iovec *iov, loff_t offset,
1786	unsigned long nr_segs)
1787	{
1788	struct file *file = iocb->ki_filp;
1789	struct inode *inode = file->f_mapping->host;
1790	struct ext3_inode_info *ei = EXT3_I(inode);
1791	handle_t *handle;
1792	ssize_t ret;
1793	int orphan = 0;
1794	size_t count = iov_length(iov, nr_segs);
1795	int retries = 0;
1796
1797	if (rw == WRITE) {
1798	loff_t final_size = offset + count;
1799
1800	if (final_size > inode->i_size) {
1801	/* Credits for sb + inode write */
1802	handle = ext3_journal_start(inode, 2);
1803	if (IS_ERR(handle)) {
1804	ret = PTR_ERR(handle);
1805	goto out;
1806	}
1807	ret = ext3_orphan_add(handle, inode);
1808	if (ret) {
1809	ext3_journal_stop(handle);
1810	goto out;
1811	}
1812	orphan = 1;
1813	ei->i_disksize = inode->i_size;
1814	ext3_journal_stop(handle);
1815	}
1816	}
1817
1818	retry:
1819	ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1820	offset, nr_segs,
1821	ext3_get_block, NULL);
1822	/*
1823	* In case of error extending write may have instantiated a few
1824	* blocks outside i_size. Trim these off again.
1825	*/
1826	if (unlikely((rw & WRITE) && ret < 0)) {
1827	loff_t isize = i_size_read(inode);
1828	loff_t end = offset + iov_length(iov, nr_segs);
1829
1830	if (end > isize)
1831	vmtruncate(inode, isize);
1832	}
1833	if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
1834	goto retry;
1835
1836	if (orphan) {
1837	int err;
1838
1839	/* Credits for sb + inode write */
1840	handle = ext3_journal_start(inode, 2);
1841	if (IS_ERR(handle)) {
1842	/* This is really bad luck. We've written the data
1843	* but cannot extend i_size. Truncate allocated blocks
1844	* and pretend the write failed... */
1845	ext3_truncate(inode);
1846	ret = PTR_ERR(handle);
1847	goto out;
1848	}
1849	if (inode->i_nlink)
1850	ext3_orphan_del(handle, inode);
1851	if (ret > 0) {
1852	loff_t end = offset + ret;
1853	if (end > inode->i_size) {
1854	ei->i_disksize = end;
1855	i_size_write(inode, end);
1856	/*
1857	* We're going to return a positive `ret'
1858	* here due to non-zero-length I/O, so there's
1859	* no way of reporting error returns from
1860	* ext3_mark_inode_dirty() to userspace. So
1861	* ignore it.
1862	*/
1863	ext3_mark_inode_dirty(handle, inode);
1864	}
1865	}
1866	err = ext3_journal_stop(handle);
1867	if (ret == 0)
1868	ret = err;
1869	}
1870	out:
1871	return ret;
1872	}
1873
1874	/*
1875	* Pages can be marked dirty completely asynchronously from ext3's journalling
1876	* activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do
1877	* much here because ->set_page_dirty is called under VFS locks. The page is
1878	* not necessarily locked.
1879	*
1880	* We cannot just dirty the page and leave attached buffers clean, because the
1881	* buffers' dirty state is "definitive". We cannot just set the buffers dirty
1882	* or jbddirty because all the journalling code will explode.
1883	*
1884	* So what we do is to mark the page "pending dirty" and next time writepage
1885	* is called, propagate that into the buffers appropriately.
1886	*/
1887	static int ext3_journalled_set_page_dirty(struct page *page)
1888	{
1889	SetPageChecked(page);
1890	return __set_page_dirty_nobuffers(page);
1891	}
1892
1893	static const struct address_space_operations ext3_ordered_aops = {
1894	.readpage = ext3_readpage,
1895	.readpages = ext3_readpages,
1896	.writepage = ext3_ordered_writepage,
1897	.write_begin = ext3_write_begin,
1898	.write_end = ext3_ordered_write_end,
1899	.bmap = ext3_bmap,
1900	.invalidatepage = ext3_invalidatepage,
1901	.releasepage = ext3_releasepage,
1902	.direct_IO = ext3_direct_IO,
1903	.migratepage = buffer_migrate_page,
1904	.is_partially_uptodate = block_is_partially_uptodate,
1905	.error_remove_page = generic_error_remove_page,
1906	};
1907
1908	static const struct address_space_operations ext3_writeback_aops = {
1909	.readpage = ext3_readpage,
1910	.readpages = ext3_readpages,
1911	.writepage = ext3_writeback_writepage,
1912	.write_begin = ext3_write_begin,
1913	.write_end = ext3_writeback_write_end,
1914	.bmap = ext3_bmap,
1915	.invalidatepage = ext3_invalidatepage,
1916	.releasepage = ext3_releasepage,
1917	.direct_IO = ext3_direct_IO,
1918	.migratepage = buffer_migrate_page,
1919	.is_partially_uptodate = block_is_partially_uptodate,
1920	.error_remove_page = generic_error_remove_page,
1921	};
1922
1923	static const struct address_space_operations ext3_journalled_aops = {
1924	.readpage = ext3_readpage,
1925	.readpages = ext3_readpages,
1926	.writepage = ext3_journalled_writepage,
1927	.write_begin = ext3_write_begin,
1928	.write_end = ext3_journalled_write_end,
1929	.set_page_dirty = ext3_journalled_set_page_dirty,
1930	.bmap = ext3_bmap,
1931	.invalidatepage = ext3_invalidatepage,
1932	.releasepage = ext3_releasepage,
1933	.is_partially_uptodate = block_is_partially_uptodate,
1934	.error_remove_page = generic_error_remove_page,
1935	};
1936
1937	void ext3_set_aops(struct inode *inode)
1938	{
1939	if (ext3_should_order_data(inode))
1940	inode->i_mapping->a_ops = &ext3_ordered_aops;
1941	else if (ext3_should_writeback_data(inode))
1942	inode->i_mapping->a_ops = &ext3_writeback_aops;
1943	else
1944	inode->i_mapping->a_ops = &ext3_journalled_aops;
1945	}
1946
1947	/*
1948	* ext3_block_truncate_page() zeroes out a mapping from file offset `from'
1949	* up to the end of the block which corresponds to `from'.
1950	* This required during truncate. We need to physically zero the tail end
1951	* of that block so it doesn't yield old data if the file is later grown.
1952	*/
1953	static int ext3_block_truncate_page(handle_t handle, struct page page,
1954	struct address_space *mapping, loff_t from)
1955	{
1956	ext3_fsblk_t index = from >> PAGE_CACHE_SHIFT;
1957	unsigned offset = from & (PAGE_CACHE_SIZE-1);
1958	unsigned blocksize, iblock, length, pos;
1959	struct inode *inode = mapping->host;
1960	struct buffer_head *bh;
1961	int err = 0;
1962
1963	blocksize = inode->i_sb->s_blocksize;
1964	length = blocksize - (offset & (blocksize - 1));
1965	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1966
1967	if (!page_has_buffers(page))
1968	create_empty_buffers(page, blocksize, 0);
1969
1970	/* Find the buffer that contains "offset" */
1971	bh = page_buffers(page);
1972	pos = blocksize;
1973	while (offset >= pos) {
1974	bh = bh->b_this_page;
1975	iblock++;
1976	pos += blocksize;
1977	}
1978
1979	err = 0;
1980	if (buffer_freed(bh)) {
1981	BUFFER_TRACE(bh, "freed: skip");
1982	goto unlock;
1983	}
1984
1985	if (!buffer_mapped(bh)) {
1986	BUFFER_TRACE(bh, "unmapped");
1987	ext3_get_block(inode, iblock, bh, 0);
1988	/* unmapped? It's a hole - nothing to do */
1989	if (!buffer_mapped(bh)) {
1990	BUFFER_TRACE(bh, "still unmapped");
1991	goto unlock;
1992	}
1993	}
1994
1995	/* Ok, it's mapped. Make sure it's up-to-date */
1996	if (PageUptodate(page))
1997	set_buffer_uptodate(bh);
1998
1999	if (!buffer_uptodate(bh)) {
2000	err = -EIO;
2001	ll_rw_block(READ, 1, &bh);
2002	wait_on_buffer(bh);
2003	/* Uhhuh. Read error. Complain and punt. */
2004	if (!buffer_uptodate(bh))
2005	goto unlock;
2006	}
2007
2008	if (ext3_should_journal_data(inode)) {
2009	BUFFER_TRACE(bh, "get write access");
2010	err = ext3_journal_get_write_access(handle, bh);
2011	if (err)
2012	goto unlock;
2013	}
2014
2015	zero_user(page, offset, length);
2016	BUFFER_TRACE(bh, "zeroed end of block");
2017
2018	err = 0;
2019	if (ext3_should_journal_data(inode)) {
2020	err = ext3_journal_dirty_metadata(handle, bh);
2021	} else {
2022	if (ext3_should_order_data(inode))
2023	err = ext3_journal_dirty_data(handle, bh);
2024	mark_buffer_dirty(bh);
2025	}
2026
2027	unlock:
2028	unlock_page(page);
2029	page_cache_release(page);
2030	return err;
2031	}
2032
2033	/*
2034	* Probably it should be a library function... search for first non-zero word
2035	* or memcmp with zero_page, whatever is better for particular architecture.
2036	* Linus?
2037	*/
2038	static inline int all_zeroes(__le32 p, __le32 q)
2039	{
2040	while (p < q)
2041	if (*p++)
2042	return 0;
2043	return 1;
2044	}
2045
2046	/**
2047	* ext3_find_shared - find the indirect blocks for partial truncation.
2048	* @inode: inode in question
2049	* @depth: depth of the affected branch
2050	* @offsets: offsets of pointers in that branch (see ext3_block_to_path)
2051	* @chain: place to store the pointers to partial indirect blocks
2052	* @top: place to the (detached) top of branch
2053	*
2054	* This is a helper function used by ext3_truncate().
2055	*
2056	* When we do truncate() we may have to clean the ends of several
2057	* indirect blocks but leave the blocks themselves alive. Block is
2058	* partially truncated if some data below the new i_size is referred
2059	* from it (and it is on the path to the first completely truncated
2060	* data block, indeed). We have to free the top of that path along
2061	* with everything to the right of the path. Since no allocation
2062	* past the truncation point is possible until ext3_truncate()
2063	* finishes, we may safely do the latter, but top of branch may
2064	* require special attention - pageout below the truncation point
2065	* might try to populate it.
2066	*
2067	* We atomically detach the top of branch from the tree, store the
2068	* block number of its root in *@top, pointers to buffer_heads of
2069	* partially truncated blocks - in @chain[].bh and pointers to
2070	* their last elements that should not be removed - in
2071	* @chain[].p. Return value is the pointer to last filled element
2072	* of @chain.
2073	*
2074	* The work left to caller to do the actual freeing of subtrees:
2075	* a) free the subtree starting from *@top
2076	* b) free the subtrees whose roots are stored in
2077	* (@chain[i].p+1 .. end of @chain[i].bh->b_data)
2078	* c) free the subtrees growing from the inode past the @chain[0].
2079	* (no partially truncated stuff there). */
2080
2081	static Indirect ext3_find_shared(struct inode inode, int depth,
2082	int offsets[4], Indirect chain[4], __le32 *top)
2083	{
2084	Indirect partial, p;
2085	int k, err;
2086
2087	*top = 0;
2088	/* Make k index the deepest non-null offset + 1 */
2089	for (k = depth; k > 1 && !offsets[k-1]; k--)
2090	;
2091	partial = ext3_get_branch(inode, k, offsets, chain, &err);
2092	/* Writer: pointers */
2093	if (!partial)
2094	partial = chain + k-1;
2095	/*
2096	* If the branch acquired continuation since we've looked at it -
2097	* fine, it should all survive and (new) top doesn't belong to us.
2098	*/
2099	if (!partial->key && *partial->p)
2100	/* Writer: end */
2101	goto no_top;
2102	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
2103	;
2104	/*
2105	* OK, we've found the last block that must survive. The rest of our
2106	* branch should be detached before unlocking. However, if that rest
2107	* of branch is all ours and does not grow immediately from the inode
2108	* it's easier to cheat and just decrement partial->p.
2109	*/
2110	if (p == chain + k - 1 && p > chain) {
2111	p->p--;
2112	} else {
2113	top = p->p;
2114	/* Nope, don't do this in ext3. Must leave the tree intact */
2115	#if 0
2116	*p->p = 0;
2117	#endif
2118	}
2119	/* Writer: end */
2120
2121	while(partial > p) {
2122	brelse(partial->bh);
2123	partial--;
2124	}
2125	no_top:
2126	return partial;
2127	}
2128
2129	/*
2130	* Zero a number of block pointers in either an inode or an indirect block.
2131	* If we restart the transaction we must again get write access to the
2132	* indirect block for further modification.
2133	*
2134	* We release `count' blocks on disk, but (last - first) may be greater
2135	* than `count' because there can be holes in there.
2136	*/
2137	static void ext3_clear_blocks(handle_t handle, struct inode inode,
2138	struct buffer_head *bh, ext3_fsblk_t block_to_free,
2139	unsigned long count, __le32 first, __le32 last)
2140	{
2141	__le32 *p;
2142	if (try_to_extend_transaction(handle, inode)) {
2143	if (bh) {
2144	BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
2145	if (ext3_journal_dirty_metadata(handle, bh))
2146	return;
2147	}
2148	ext3_mark_inode_dirty(handle, inode);
2149	truncate_restart_transaction(handle, inode);
2150	if (bh) {
2151	BUFFER_TRACE(bh, "retaking write access");
2152	if (ext3_journal_get_write_access(handle, bh))
2153	return;
2154	}
2155	}
2156
2157	/*
2158	* Any buffers which are on the journal will be in memory. We find
2159	* them on the hash table so journal_revoke() will run journal_forget()
2160	* on them. We've already detached each block from the file, so
2161	* bforget() in journal_forget() should be safe.
2162	*
2163	* AKPM: turn on bforget in journal_forget()!!!
2164	*/
2165	for (p = first; p < last; p++) {
2166	u32 nr = le32_to_cpu(*p);
2167	if (nr) {
2168	struct buffer_head *bh;
2169
2170	*p = 0;
2171	bh = sb_find_get_block(inode->i_sb, nr);
2172	ext3_forget(handle, 0, inode, bh, nr);
2173	}
2174	}
2175
2176	ext3_free_blocks(handle, inode, block_to_free, count);
2177	}
2178
2179	/**
2180	* ext3_free_data - free a list of data blocks
2181	* @handle: handle for this transaction
2182	* @inode: inode we are dealing with
2183	* @this_bh: indirect buffer_head which contains @first and @last
2184	* @first: array of block numbers
2185	* @last: points immediately past the end of array
2186	*
2187	* We are freeing all blocks referred from that array (numbers are stored as
2188	* little-endian 32-bit) and updating @inode->i_blocks appropriately.
2189	*
2190	* We accumulate contiguous runs of blocks to free. Conveniently, if these
2191	* blocks are contiguous then releasing them at one time will only affect one
2192	* or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
2193	* actually use a lot of journal space.
2194	*
2195	* @this_bh will be %NULL if @first and @last point into the inode's direct
2196	* block pointers.
2197	*/
2198	static void ext3_free_data(handle_t handle, struct inode inode,
2199	struct buffer_head *this_bh,
2200	__le32 first, __le32 last)
2201	{
2202	ext3_fsblk_t block_to_free = 0; /* Starting block # of a run */
2203	unsigned long count = 0; /* Number of blocks in the run */
2204	__le32 block_to_free_p = NULL; / Pointer into inode/ind
2205	corresponding to
2206	block_to_free */
2207	ext3_fsblk_t nr; /* Current block # */
2208	__le32 p; / Pointer into inode/ind
2209	for current block */
2210	int err;
2211
2212	if (this_bh) { /* For indirect block */
2213	BUFFER_TRACE(this_bh, "get_write_access");
2214	err = ext3_journal_get_write_access(handle, this_bh);
2215	/* Important: if we can't update the indirect pointers
2216	* to the blocks, we can't free them. */
2217	if (err)
2218	return;
2219	}
2220
2221	for (p = first; p < last; p++) {
2222	nr = le32_to_cpu(*p);
2223	if (nr) {
2224	/* accumulate blocks to free if they're contiguous */
2225	if (count == 0) {
2226	block_to_free = nr;
2227	block_to_free_p = p;
2228	count = 1;
2229	} else if (nr == block_to_free + count) {
2230	count++;
2231	} else {
2232	ext3_clear_blocks(handle, inode, this_bh,
2233	block_to_free,
2234	count, block_to_free_p, p);
2235	block_to_free = nr;
2236	block_to_free_p = p;
2237	count = 1;
2238	}
2239	}
2240	}
2241
2242	if (count > 0)
2243	ext3_clear_blocks(handle, inode, this_bh, block_to_free,
2244	count, block_to_free_p, p);
2245
2246	if (this_bh) {
2247	BUFFER_TRACE(this_bh, "call ext3_journal_dirty_metadata");
2248
2249	/*
2250	* The buffer head should have an attached journal head at this
2251	* point. However, if the data is corrupted and an indirect
2252	* block pointed to itself, it would have been detached when
2253	* the block was cleared. Check for this instead of OOPSing.
2254	*/
2255	if (bh2jh(this_bh))
2256	ext3_journal_dirty_metadata(handle, this_bh);
2257	else
2258	ext3_error(inode->i_sb, "ext3_free_data",
2259	"circular indirect block detected, "
2260	"inode=%lu, block=%llu",
2261	inode->i_ino,
2262	(unsigned long long)this_bh->b_blocknr);
2263	}
2264	}
2265
2266	/**
2267	* ext3_free_branches - free an array of branches
2268	* @handle: JBD handle for this transaction
2269	* @inode: inode we are dealing with
2270	* @parent_bh: the buffer_head which contains @first and @last
2271	* @first: array of block numbers
2272	* @last: pointer immediately past the end of array
2273	* @depth: depth of the branches to free
2274	*
2275	* We are freeing all blocks referred from these branches (numbers are
2276	* stored as little-endian 32-bit) and updating @inode->i_blocks
2277	* appropriately.
2278	*/
2279	static void ext3_free_branches(handle_t handle, struct inode inode,
2280	struct buffer_head *parent_bh,
2281	__le32 first, __le32 last, int depth)
2282	{
2283	ext3_fsblk_t nr;
2284	__le32 *p;
2285
2286	if (is_handle_aborted(handle))
2287	return;
2288
2289	if (depth--) {
2290	struct buffer_head *bh;
2291	int addr_per_block = EXT3_ADDR_PER_BLOCK(inode->i_sb);
2292	p = last;
2293	while (--p >= first) {
2294	nr = le32_to_cpu(*p);
2295	if (!nr)
2296	continue; /* A hole */
2297
2298	/* Go read the buffer for the next level down */
2299	bh = sb_bread(inode->i_sb, nr);
2300
2301	/*
2302	* A read failure? Report error and clear slot
2303	* (should be rare).
2304	*/
2305	if (!bh) {
2306	ext3_error(inode->i_sb, "ext3_free_branches",
2307	"Read failure, inode=%lu, block="E3FSBLK,
2308	inode->i_ino, nr);
2309	continue;
2310	}
2311
2312	/* This zaps the entire block. Bottom up. */
2313	BUFFER_TRACE(bh, "free child branches");
2314	ext3_free_branches(handle, inode, bh,
2315	(__le32*)bh->b_data,
2316	(__le32*)bh->b_data + addr_per_block,
2317	depth);
2318
2319	/*
2320	* Everything below this this pointer has been
2321	* released. Now let this top-of-subtree go.
2322	*
2323	* We want the freeing of this indirect block to be
2324	* atomic in the journal with the updating of the
2325	* bitmap block which owns it. So make some room in
2326	* the journal.
2327	*
2328	* We zero the parent pointer after freeing its
2329	* pointee in the bitmaps, so if extend_transaction()
2330	* for some reason fails to put the bitmap changes and
2331	* the release into the same transaction, recovery
2332	* will merely complain about releasing a free block,
2333	* rather than leaking blocks.
2334	*/
2335	if (is_handle_aborted(handle))
2336	return;
2337	if (try_to_extend_transaction(handle, inode)) {
2338	ext3_mark_inode_dirty(handle, inode);
2339	truncate_restart_transaction(handle, inode);
2340	}
2341
2342	/*
2343	* We've probably journalled the indirect block several
2344	* times during the truncate. But it's no longer
2345	* needed and we now drop it from the transaction via
2346	* journal_revoke().
2347	*
2348	* That's easy if it's exclusively part of this
2349	* transaction. But if it's part of the committing
2350	* transaction then journal_forget() will simply
2351	* brelse() it. That means that if the underlying
2352	* block is reallocated in ext3_get_block(),
2353	* unmap_underlying_metadata() will find this block
2354	* and will try to get rid of it. damn, damn. Thus
2355	* we don't allow a block to be reallocated until
2356	* a transaction freeing it has fully committed.
2357	*
2358	* We also have to make sure journal replay after a
2359	* crash does not overwrite non-journaled data blocks
2360	* with old metadata when the block got reallocated for
2361	* data. Thus we have to store a revoke record for a
2362	* block in the same transaction in which we free the
2363	* block.
2364	*/
2365	ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
2366
2367	ext3_free_blocks(handle, inode, nr, 1);
2368
2369	if (parent_bh) {
2370	/*
2371	* The block which we have just freed is
2372	* pointed to by an indirect block: journal it
2373	*/
2374	BUFFER_TRACE(parent_bh, "get_write_access");
2375	if (!ext3_journal_get_write_access(handle,
2376	parent_bh)){
2377	*p = 0;
2378	BUFFER_TRACE(parent_bh,
2379	"call ext3_journal_dirty_metadata");
2380	ext3_journal_dirty_metadata(handle,
2381	parent_bh);
2382	}
2383	}
2384	}
2385	} else {
2386	/* We have reached the bottom of the tree. */
2387	BUFFER_TRACE(parent_bh, "free data blocks");
2388	ext3_free_data(handle, inode, parent_bh, first, last);
2389	}
2390	}
2391
2392	int ext3_can_truncate(struct inode *inode)
2393	{
2394	if (IS_APPEND(inode) \|\| IS_IMMUTABLE(inode))
2395	return 0;
2396	if (S_ISREG(inode->i_mode))
2397	return 1;
2398	if (S_ISDIR(inode->i_mode))
2399	return 1;
2400	if (S_ISLNK(inode->i_mode))
2401	return !ext3_inode_is_fast_symlink(inode);
2402	return 0;
2403	}
2404
2405	/*
2406	* ext3_truncate()
2407	*
2408	* We block out ext3_get_block() block instantiations across the entire
2409	* transaction, and VFS/VM ensures that ext3_truncate() cannot run
2410	* simultaneously on behalf of the same inode.
2411	*
2412	* As we work through the truncate and commmit bits of it to the journal there
2413	* is one core, guiding principle: the file's tree must always be consistent on
2414	* disk. We must be able to restart the truncate after a crash.
2415	*
2416	* The file's tree may be transiently inconsistent in memory (although it
2417	* probably isn't), but whenever we close off and commit a journal transaction,
2418	* the contents of (the filesystem + the journal) must be consistent and
2419	* restartable. It's pretty simple, really: bottom up, right to left (although
2420	* left-to-right works OK too).
2421	*
2422	* Note that at recovery time, journal replay occurs before the restart of
2423	* truncate against the orphan inode list.
2424	*
2425	* The committed inode has the new, desired i_size (which is the same as
2426	* i_disksize in this case). After a crash, ext3_orphan_cleanup() will see
2427	* that this inode's truncate did not complete and it will again call
2428	* ext3_truncate() to have another go. So there will be instantiated blocks
2429	* to the right of the truncation point in a crashed ext3 filesystem. But
2430	* that's fine - as long as they are linked from the inode, the post-crash
2431	* ext3_truncate() run will find them and release them.
2432	*/
2433	void ext3_truncate(struct inode *inode)
2434	{
2435	handle_t *handle;
2436	struct ext3_inode_info *ei = EXT3_I(inode);
2437	__le32 *i_data = ei->i_data;
2438	int addr_per_block = EXT3_ADDR_PER_BLOCK(inode->i_sb);
2439	struct address_space *mapping = inode->i_mapping;
2440	int offsets[4];
2441	Indirect chain[4];
2442	Indirect *partial;
2443	__le32 nr = 0;
2444	int n;
2445	long last_block;
2446	unsigned blocksize = inode->i_sb->s_blocksize;
2447	struct page *page;
2448
2449	if (!ext3_can_truncate(inode))
2450	goto out_notrans;
2451
2452	if (inode->i_size == 0 && ext3_should_writeback_data(inode))
2453	ext3_set_inode_state(inode, EXT3_STATE_FLUSH_ON_CLOSE);
2454
2455	/*
2456	* We have to lock the EOF page here, because lock_page() nests
2457	* outside journal_start().
2458	*/
2459	if ((inode->i_size & (blocksize - 1)) == 0) {
2460	/* Block boundary? Nothing to do */
2461	page = NULL;
2462	} else {
2463	page = grab_cache_page(mapping,
2464	inode->i_size >> PAGE_CACHE_SHIFT);
2465	if (!page)
2466	goto out_notrans;
2467	}
2468
2469	handle = start_transaction(inode);
2470	if (IS_ERR(handle)) {
2471	if (page) {
2472	clear_highpage(page);
2473	flush_dcache_page(page);
2474	unlock_page(page);
2475	page_cache_release(page);
2476	}
2477	goto out_notrans;
2478	}
2479
2480	last_block = (inode->i_size + blocksize-1)
2481	>> EXT3_BLOCK_SIZE_BITS(inode->i_sb);
2482
2483	if (page)
2484	ext3_block_truncate_page(handle, page, mapping, inode->i_size);
2485
2486	n = ext3_block_to_path(inode, last_block, offsets, NULL);
2487	if (n == 0)
2488	goto out_stop; /* error */
2489
2490	/*
2491	* OK. This truncate is going to happen. We add the inode to the
2492	* orphan list, so that if this truncate spans multiple transactions,
2493	* and we crash, we will resume the truncate when the filesystem
2494	* recovers. It also marks the inode dirty, to catch the new size.
2495	*
2496	* Implication: the file must always be in a sane, consistent
2497	* truncatable state while each transaction commits.
2498	*/
2499	if (ext3_orphan_add(handle, inode))
2500	goto out_stop;
2501
2502	/*
2503	* The orphan list entry will now protect us from any crash which
2504	* occurs before the truncate completes, so it is now safe to propagate
2505	* the new, shorter inode size (held for now in i_size) into the
2506	* on-disk inode. We do this via i_disksize, which is the value which
2507	* ext3 really writes onto the disk inode.
2508	*/
2509	ei->i_disksize = inode->i_size;
2510
2511	/*
2512	* From here we block out all ext3_get_block() callers who want to
2513	* modify the block allocation tree.
2514	*/
2515	mutex_lock(&ei->truncate_mutex);
2516
2517	if (n == 1) { /* direct blocks */
2518	ext3_free_data(handle, inode, NULL, i_data+offsets[0],
2519	i_data + EXT3_NDIR_BLOCKS);
2520	goto do_indirects;
2521	}
2522
2523	partial = ext3_find_shared(inode, n, offsets, chain, &nr);
2524	/* Kill the top of shared branch (not detached) */
2525	if (nr) {
2526	if (partial == chain) {
2527	/* Shared branch grows from the inode */
2528	ext3_free_branches(handle, inode, NULL,
2529	&nr, &nr+1, (chain+n-1) - partial);
2530	*partial->p = 0;
2531	/*
2532	* We mark the inode dirty prior to restart,
2533	* and prior to stop. No need for it here.
2534	*/
2535	} else {
2536	/* Shared branch grows from an indirect block */
2537	ext3_free_branches(handle, inode, partial->bh,
2538	partial->p,
2539	partial->p+1, (chain+n-1) - partial);
2540	}
2541	}
2542	/* Clear the ends of indirect blocks on the shared branch */
2543	while (partial > chain) {
2544	ext3_free_branches(handle, inode, partial->bh, partial->p + 1,
2545	(__le32*)partial->bh->b_data+addr_per_block,
2546	(chain+n-1) - partial);
2547	BUFFER_TRACE(partial->bh, "call brelse");
2548	brelse (partial->bh);
2549	partial--;
2550	}
2551	do_indirects:
2552	/* Kill the remaining (whole) subtrees */
2553	switch (offsets[0]) {
2554	default:
2555	nr = i_data[EXT3_IND_BLOCK];
2556	if (nr) {
2557	ext3_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
2558	i_data[EXT3_IND_BLOCK] = 0;
2559	}
2560	case EXT3_IND_BLOCK:
2561	nr = i_data[EXT3_DIND_BLOCK];
2562	if (nr) {
2563	ext3_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
2564	i_data[EXT3_DIND_BLOCK] = 0;
2565	}
2566	case EXT3_DIND_BLOCK:
2567	nr = i_data[EXT3_TIND_BLOCK];
2568	if (nr) {
2569	ext3_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
2570	i_data[EXT3_TIND_BLOCK] = 0;
2571	}
2572	case EXT3_TIND_BLOCK:
2573	;
2574	}
2575
2576	ext3_discard_reservation(inode);
2577
2578	mutex_unlock(&ei->truncate_mutex);
2579	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
2580	ext3_mark_inode_dirty(handle, inode);
2581
2582	/*
2583	* In a multi-transaction truncate, we only make the final transaction
2584	* synchronous
2585	*/
2586	if (IS_SYNC(inode))
2587	handle->h_sync = 1;
2588	out_stop:
2589	/*
2590	* If this was a simple ftruncate(), and the file will remain alive
2591	* then we need to clear up the orphan record which we created above.
2592	* However, if this was a real unlink then we were called by
2593	* ext3_evict_inode(), and we allow that function to clean up the
2594	* orphan info for us.
2595	*/
2596	if (inode->i_nlink)
2597	ext3_orphan_del(handle, inode);
2598
2599	ext3_journal_stop(handle);
2600	return;
2601	out_notrans:
2602	/*
2603	* Delete the inode from orphan list so that it doesn't stay there
2604	* forever and trigger assertion on umount.
2605	*/
2606	if (inode->i_nlink)
2607	ext3_orphan_del(NULL, inode);
2608	}
2609
2610	static ext3_fsblk_t ext3_get_inode_block(struct super_block *sb,
2611	unsigned long ino, struct ext3_iloc *iloc)
2612	{
2613	unsigned long block_group;
2614	unsigned long offset;
2615	ext3_fsblk_t block;
2616	struct ext3_group_desc *gdp;
2617
2618	if (!ext3_valid_inum(sb, ino)) {
2619	/*
2620	* This error is already checked for in namei.c unless we are
2621	* looking at an NFS filehandle, in which case no error
2622	* report is needed
2623	*/
2624	return 0;
2625	}
2626
2627	block_group = (ino - 1) / EXT3_INODES_PER_GROUP(sb);
2628	gdp = ext3_get_group_desc(sb, block_group, NULL);
2629	if (!gdp)
2630	return 0;
2631	/*
2632	* Figure out the offset within the block group inode table
2633	*/
2634	offset = ((ino - 1) % EXT3_INODES_PER_GROUP(sb)) *
2635	EXT3_INODE_SIZE(sb);
2636	block = le32_to_cpu(gdp->bg_inode_table) +
2637	(offset >> EXT3_BLOCK_SIZE_BITS(sb));
2638
2639	iloc->block_group = block_group;
2640	iloc->offset = offset & (EXT3_BLOCK_SIZE(sb) - 1);
2641	return block;
2642	}
2643
2644	/*
2645	* ext3_get_inode_loc returns with an extra refcount against the inode's
2646	* underlying buffer_head on success. If 'in_mem' is true, we have all
2647	* data in memory that is needed to recreate the on-disk version of this
2648	* inode.
2649	*/
2650	static int __ext3_get_inode_loc(struct inode *inode,
2651	struct ext3_iloc *iloc, int in_mem)
2652	{
2653	ext3_fsblk_t block;
2654	struct buffer_head *bh;
2655
2656	block = ext3_get_inode_block(inode->i_sb, inode->i_ino, iloc);
2657	if (!block)
2658	return -EIO;
2659
2660	bh = sb_getblk(inode->i_sb, block);
2661	if (!bh) {
2662	ext3_error (inode->i_sb, "ext3_get_inode_loc",
2663	"unable to read inode block - "
2664	"inode=%lu, block="E3FSBLK,
2665	inode->i_ino, block);
2666	return -EIO;
2667	}
2668	if (!buffer_uptodate(bh)) {
2669	lock_buffer(bh);
2670
2671	/*
2672	* If the buffer has the write error flag, we have failed
2673	* to write out another inode in the same block. In this
2674	* case, we don't have to read the block because we may
2675	* read the old inode data successfully.
2676	*/
2677	if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
2678	set_buffer_uptodate(bh);
2679
2680	if (buffer_uptodate(bh)) {
2681	/* someone brought it uptodate while we waited */
2682	unlock_buffer(bh);
2683	goto has_buffer;
2684	}
2685
2686	/*
2687	* If we have all information of the inode in memory and this
2688	* is the only valid inode in the block, we need not read the
2689	* block.
2690	*/
2691	if (in_mem) {
2692	struct buffer_head *bitmap_bh;
2693	struct ext3_group_desc *desc;
2694	int inodes_per_buffer;
2695	int inode_offset, i;
2696	int block_group;
2697	int start;
2698
2699	block_group = (inode->i_ino - 1) /
2700	EXT3_INODES_PER_GROUP(inode->i_sb);
2701	inodes_per_buffer = bh->b_size /
2702	EXT3_INODE_SIZE(inode->i_sb);
2703	inode_offset = ((inode->i_ino - 1) %
2704	EXT3_INODES_PER_GROUP(inode->i_sb));
2705	start = inode_offset & ~(inodes_per_buffer - 1);
2706
2707	/* Is the inode bitmap in cache? */
2708	desc = ext3_get_group_desc(inode->i_sb,
2709	block_group, NULL);
2710	if (!desc)
2711	goto make_io;
2712
2713	bitmap_bh = sb_getblk(inode->i_sb,
2714	le32_to_cpu(desc->bg_inode_bitmap));
2715	if (!bitmap_bh)
2716	goto make_io;
2717
2718	/*
2719	* If the inode bitmap isn't in cache then the
2720	* optimisation may end up performing two reads instead
2721	* of one, so skip it.
2722	*/
2723	if (!buffer_uptodate(bitmap_bh)) {
2724	brelse(bitmap_bh);
2725	goto make_io;
2726	}
2727	for (i = start; i < start + inodes_per_buffer; i++) {
2728	if (i == inode_offset)
2729	continue;
2730	if (ext3_test_bit(i, bitmap_bh->b_data))
2731	break;
2732	}
2733	brelse(bitmap_bh);
2734	if (i == start + inodes_per_buffer) {
2735	/* all other inodes are free, so skip I/O */
2736	memset(bh->b_data, 0, bh->b_size);
2737	set_buffer_uptodate(bh);
2738	unlock_buffer(bh);
2739	goto has_buffer;
2740	}
2741	}
2742
2743	make_io:
2744	/*
2745	* There are other valid inodes in the buffer, this inode
2746	* has in-inode xattrs, or we don't have this inode in memory.
2747	* Read the block from disk.
2748	*/
2749	get_bh(bh);
2750	bh->b_end_io = end_buffer_read_sync;
2751	submit_bh(READ_META, bh);
2752	wait_on_buffer(bh);
2753	if (!buffer_uptodate(bh)) {
2754	ext3_error(inode->i_sb, "ext3_get_inode_loc",
2755	"unable to read inode block - "
2756	"inode=%lu, block="E3FSBLK,
2757	inode->i_ino, block);
2758	brelse(bh);
2759	return -EIO;
2760	}
2761	}
2762	has_buffer:
2763	iloc->bh = bh;
2764	return 0;
2765	}
2766
2767	int ext3_get_inode_loc(struct inode inode, struct ext3_iloc iloc)
2768	{
2769	/* We have all inode data except xattrs in memory here. */
2770	return __ext3_get_inode_loc(inode, iloc,
2771	!ext3_test_inode_state(inode, EXT3_STATE_XATTR));
2772	}
2773
2774	void ext3_set_inode_flags(struct inode *inode)
2775	{
2776	unsigned int flags = EXT3_I(inode)->i_flags;
2777
2778	inode->i_flags &= ~(S_SYNC\|S_APPEND\|S_IMMUTABLE\|S_NOATIME\|S_DIRSYNC);
2779	if (flags & EXT3_SYNC_FL)
2780	inode->i_flags \|= S_SYNC;
2781	if (flags & EXT3_APPEND_FL)
2782	inode->i_flags \|= S_APPEND;
2783	if (flags & EXT3_IMMUTABLE_FL)
2784	inode->i_flags \|= S_IMMUTABLE;
2785	if (flags & EXT3_NOATIME_FL)
2786	inode->i_flags \|= S_NOATIME;
2787	if (flags & EXT3_DIRSYNC_FL)
2788	inode->i_flags \|= S_DIRSYNC;
2789	}
2790
2791	/* Propagate flags from i_flags to EXT3_I(inode)->i_flags */
2792	void ext3_get_inode_flags(struct ext3_inode_info *ei)
2793	{
2794	unsigned int flags = ei->vfs_inode.i_flags;
2795
2796	ei->i_flags &= ~(EXT3_SYNC_FL\|EXT3_APPEND_FL\|
2797	EXT3_IMMUTABLE_FL\|EXT3_NOATIME_FL\|EXT3_DIRSYNC_FL);
2798	if (flags & S_SYNC)
2799	ei->i_flags \|= EXT3_SYNC_FL;
2800	if (flags & S_APPEND)
2801	ei->i_flags \|= EXT3_APPEND_FL;
2802	if (flags & S_IMMUTABLE)
2803	ei->i_flags \|= EXT3_IMMUTABLE_FL;
2804	if (flags & S_NOATIME)
2805	ei->i_flags \|= EXT3_NOATIME_FL;
2806	if (flags & S_DIRSYNC)
2807	ei->i_flags \|= EXT3_DIRSYNC_FL;
2808	}
2809
2810	struct inode ext3_iget(struct super_block sb, unsigned long ino)
2811	{
2812	struct ext3_iloc iloc;
2813	struct ext3_inode *raw_inode;
2814	struct ext3_inode_info *ei;
2815	struct buffer_head *bh;
2816	struct inode *inode;
2817	journal_t *journal = EXT3_SB(sb)->s_journal;
2818	transaction_t *transaction;
2819	long ret;
2820	int block;
2821
2822	inode = iget_locked(sb, ino);
2823	if (!inode)
2824	return ERR_PTR(-ENOMEM);
2825	if (!(inode->i_state & I_NEW))
2826	return inode;
2827
2828	ei = EXT3_I(inode);
2829	ei->i_block_alloc_info = NULL;
2830
2831	ret = __ext3_get_inode_loc(inode, &iloc, 0);
2832	if (ret < 0)
2833	goto bad_inode;
2834	bh = iloc.bh;
2835	raw_inode = ext3_raw_inode(&iloc);
2836	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
2837	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
2838	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
2839	if(!(test_opt (inode->i_sb, NO_UID32))) {
2840	inode->i_uid \|= le16_to_cpu(raw_inode->i_uid_high) << 16;
2841	inode->i_gid \|= le16_to_cpu(raw_inode->i_gid_high) << 16;
2842	}
2843	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
2844	inode->i_size = le32_to_cpu(raw_inode->i_size);
2845	inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
2846	inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
2847	inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
2848	inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = inode->i_mtime.tv_nsec = 0;
2849
2850	ei->i_state_flags = 0;
2851	ei->i_dir_start_lookup = 0;
2852	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
2853	/* We now have enough fields to check if the inode was active or not.
2854	* This is needed because nfsd might try to access dead inodes
2855	* the test is that same one that e2fsck uses
2856	* NeilBrown 1999oct15
2857	*/
2858	if (inode->i_nlink == 0) {
2859	if (inode->i_mode == 0 \|\|
2860	!(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ORPHAN_FS)) {
2861	/* this inode is deleted */
2862	brelse (bh);
2863	ret = -ESTALE;
2864	goto bad_inode;
2865	}
2866	/* The only unlinked inodes we let through here have
2867	* valid i_mode and are being read by the orphan
2868	* recovery code: that's fine, we're about to complete
2869	* the process of deleting those. */
2870	}
2871	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
2872	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
2873	#ifdef EXT3_FRAGMENTS
2874	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
2875	ei->i_frag_no = raw_inode->i_frag;
2876	ei->i_frag_size = raw_inode->i_fsize;
2877	#endif
2878	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
2879	if (!S_ISREG(inode->i_mode)) {
2880	ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
2881	} else {
2882	inode->i_size \|=
2883	((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
2884	}
2885	ei->i_disksize = inode->i_size;
2886	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
2887	ei->i_block_group = iloc.block_group;
2888	/*
2889	* NOTE! The in-memory inode i_data array is in little-endian order
2890	* even on big-endian machines: we do NOT byteswap the block numbers!
2891	*/
2892	for (block = 0; block < EXT3_N_BLOCKS; block++)
2893	ei->i_data[block] = raw_inode->i_block[block];
2894	INIT_LIST_HEAD(&ei->i_orphan);
2895
2896	/*
2897	* Set transaction id's of transactions that have to be committed
2898	* to finish f[data]sync. We set them to currently running transaction
2899	* as we cannot be sure that the inode or some of its metadata isn't
2900	* part of the transaction - the inode could have been reclaimed and
2901	* now it is reread from disk.
2902	*/
2903	if (journal) {
2904	tid_t tid;
2905
2906	spin_lock(&journal->j_state_lock);
2907	if (journal->j_running_transaction)
2908	transaction = journal->j_running_transaction;
2909	else
2910	transaction = journal->j_committing_transaction;
2911	if (transaction)
2912	tid = transaction->t_tid;
2913	else
2914	tid = journal->j_commit_sequence;
2915	spin_unlock(&journal->j_state_lock);
2916	atomic_set(&ei->i_sync_tid, tid);
2917	atomic_set(&ei->i_datasync_tid, tid);
2918	}
2919
2920	if (inode->i_ino >= EXT3_FIRST_INO(inode->i_sb) + 1 &&
2921	EXT3_INODE_SIZE(inode->i_sb) > EXT3_GOOD_OLD_INODE_SIZE) {
2922	/*
2923	* When mke2fs creates big inodes it does not zero out
2924	* the unused bytes above EXT3_GOOD_OLD_INODE_SIZE,
2925	* so ignore those first few inodes.
2926	*/
2927	ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
2928	if (EXT3_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
2929	EXT3_INODE_SIZE(inode->i_sb)) {
2930	brelse (bh);
2931	ret = -EIO;
2932	goto bad_inode;
2933	}
2934	if (ei->i_extra_isize == 0) {
2935	/* The extra space is currently unused. Use it. */
2936	ei->i_extra_isize = sizeof(struct ext3_inode) -
2937	EXT3_GOOD_OLD_INODE_SIZE;
2938	} else {
2939	__le32 magic = (void )raw_inode +
2940	EXT3_GOOD_OLD_INODE_SIZE +
2941	ei->i_extra_isize;
2942	if (*magic == cpu_to_le32(EXT3_XATTR_MAGIC))
2943	ext3_set_inode_state(inode, EXT3_STATE_XATTR);
2944	}
2945	} else
2946	ei->i_extra_isize = 0;
2947
2948	if (S_ISREG(inode->i_mode)) {
2949	inode->i_op = &ext3_file_inode_operations;
2950	inode->i_fop = &ext3_file_operations;
2951	ext3_set_aops(inode);
2952	} else if (S_ISDIR(inode->i_mode)) {
2953	inode->i_op = &ext3_dir_inode_operations;
2954	inode->i_fop = &ext3_dir_operations;
2955	} else if (S_ISLNK(inode->i_mode)) {
2956	if (ext3_inode_is_fast_symlink(inode)) {
2957	inode->i_op = &ext3_fast_symlink_inode_operations;
2958	nd_terminate_link(ei->i_data, inode->i_size,
2959	sizeof(ei->i_data) - 1);
2960	} else {
2961	inode->i_op = &ext3_symlink_inode_operations;
2962	ext3_set_aops(inode);
2963	}
2964	} else {
2965	inode->i_op = &ext3_special_inode_operations;
2966	if (raw_inode->i_block[0])
2967	init_special_inode(inode, inode->i_mode,
2968	old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
2969	else
2970	init_special_inode(inode, inode->i_mode,
2971	new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
2972	}
2973	brelse (iloc.bh);
2974	ext3_set_inode_flags(inode);
2975	unlock_new_inode(inode);
2976	return inode;
2977
2978	bad_inode:
2979	iget_failed(inode);
2980	return ERR_PTR(ret);
2981	}
2982
2983	/*
2984	* Post the struct inode info into an on-disk inode location in the
2985	* buffer-cache. This gobbles the caller's reference to the
2986	* buffer_head in the inode location struct.
2987	*
2988	* The caller must have write access to iloc->bh.
2989	*/
2990	static int ext3_do_update_inode(handle_t *handle,
2991	struct inode *inode,
2992	struct ext3_iloc *iloc)
2993	{
2994	struct ext3_inode *raw_inode = ext3_raw_inode(iloc);
2995	struct ext3_inode_info *ei = EXT3_I(inode);
2996	struct buffer_head *bh = iloc->bh;
2997	int err = 0, rc, block;
2998
2999	again:
3000	/* we can't allow multiple procs in here at once, its a bit racey */
3001	lock_buffer(bh);
3002
3003	/* For fields not not tracking in the in-memory inode,
3004	* initialise them to zero for new inodes. */
3005	if (ext3_test_inode_state(inode, EXT3_STATE_NEW))
3006	memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
3007
3008	ext3_get_inode_flags(ei);
3009	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
3010	if(!(test_opt(inode->i_sb, NO_UID32))) {
3011	raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
3012	raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
3013	/*
3014	* Fix up interoperability with old kernels. Otherwise, old inodes get
3015	* re-used with the upper 16 bits of the uid/gid intact
3016	*/
3017	if(!ei->i_dtime) {
3018	raw_inode->i_uid_high =
3019	cpu_to_le16(high_16_bits(inode->i_uid));
3020	raw_inode->i_gid_high =
3021	cpu_to_le16(high_16_bits(inode->i_gid));
3022	} else {
3023	raw_inode->i_uid_high = 0;
3024	raw_inode->i_gid_high = 0;
3025	}
3026	} else {
3027	raw_inode->i_uid_low =
3028	cpu_to_le16(fs_high2lowuid(inode->i_uid));
3029	raw_inode->i_gid_low =
3030	cpu_to_le16(fs_high2lowgid(inode->i_gid));
3031	raw_inode->i_uid_high = 0;
3032	raw_inode->i_gid_high = 0;
3033	}
3034	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
3035	raw_inode->i_size = cpu_to_le32(ei->i_disksize);
3036	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
3037	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
3038	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
3039	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
3040	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
3041	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
3042	#ifdef EXT3_FRAGMENTS
3043	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
3044	raw_inode->i_frag = ei->i_frag_no;
3045	raw_inode->i_fsize = ei->i_frag_size;
3046	#endif
3047	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
3048	if (!S_ISREG(inode->i_mode)) {
3049	raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
3050	} else {
3051	raw_inode->i_size_high =
3052	cpu_to_le32(ei->i_disksize >> 32);
3053	if (ei->i_disksize > 0x7fffffffULL) {
3054	struct super_block *sb = inode->i_sb;
3055	if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
3056	EXT3_FEATURE_RO_COMPAT_LARGE_FILE) \|\|
3057	EXT3_SB(sb)->s_es->s_rev_level ==
3058	cpu_to_le32(EXT3_GOOD_OLD_REV)) {
3059	/* If this is the first large file
3060	* created, add a flag to the superblock.
3061	*/
3062	unlock_buffer(bh);
3063	err = ext3_journal_get_write_access(handle,
3064	EXT3_SB(sb)->s_sbh);
3065	if (err)
3066	goto out_brelse;
3067
3068	ext3_update_dynamic_rev(sb);
3069	EXT3_SET_RO_COMPAT_FEATURE(sb,
3070	EXT3_FEATURE_RO_COMPAT_LARGE_FILE);
3071	handle->h_sync = 1;
3072	err = ext3_journal_dirty_metadata(handle,
3073	EXT3_SB(sb)->s_sbh);
3074	/* get our lock and start over */
3075	goto again;
3076	}
3077	}
3078	}
3079	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
3080	if (S_ISCHR(inode->i_mode) \|\| S_ISBLK(inode->i_mode)) {
3081	if (old_valid_dev(inode->i_rdev)) {
3082	raw_inode->i_block[0] =
3083	cpu_to_le32(old_encode_dev(inode->i_rdev));
3084	raw_inode->i_block[1] = 0;
3085	} else {
3086	raw_inode->i_block[0] = 0;
3087	raw_inode->i_block[1] =
3088	cpu_to_le32(new_encode_dev(inode->i_rdev));
3089	raw_inode->i_block[2] = 0;
3090	}
3091	} else for (block = 0; block < EXT3_N_BLOCKS; block++)
3092	raw_inode->i_block[block] = ei->i_data[block];
3093
3094	if (ei->i_extra_isize)
3095	raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
3096
3097	BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
3098	unlock_buffer(bh);
3099	rc = ext3_journal_dirty_metadata(handle, bh);
3100	if (!err)
3101	err = rc;
3102	ext3_clear_inode_state(inode, EXT3_STATE_NEW);
3103
3104	atomic_set(&ei->i_sync_tid, handle->h_transaction->t_tid);
3105	out_brelse:
3106	brelse (bh);
3107	ext3_std_error(inode->i_sb, err);
3108	return err;
3109	}
3110
3111	/*
3112	* ext3_write_inode()
3113	*
3114	* We are called from a few places:
3115	*
3116	* - Within generic_file_write() for O_SYNC files.
3117	* Here, there will be no transaction running. We wait for any running
3118	* trasnaction to commit.
3119	*
3120	* - Within sys_sync(), kupdate and such.
3121	* We wait on commit, if tol to.
3122	*
3123	* - Within prune_icache() (PF_MEMALLOC == true)
3124	* Here we simply return. We can't afford to block kswapd on the
3125	* journal commit.
3126	*
3127	* In all cases it is actually safe for us to return without doing anything,
3128	* because the inode has been copied into a raw inode buffer in
3129	* ext3_mark_inode_dirty(). This is a correctness thing for O_SYNC and for
3130	* knfsd.
3131	*
3132	* Note that we are absolutely dependent upon all inode dirtiers doing the
3133	* right thing: they must call mark_inode_dirty() after dirtying info in
3134	* which we are interested.
3135	*
3136	* It would be a bug for them to not do this. The code:
3137	*
3138	* mark_inode_dirty(inode)
3139	* stuff();
3140	* inode->i_size = expr;
3141	*
3142	* is in error because a kswapd-driven write_inode() could occur while
3143	* `stuff()' is running, and the new i_size will be lost. Plus the inode
3144	* will no longer be on the superblock's dirty inode list.
3145	*/
3146	int ext3_write_inode(struct inode inode, struct writeback_control wbc)
3147	{
3148	if (current->flags & PF_MEMALLOC)
3149	return 0;
3150
3151	if (ext3_journal_current_handle()) {
3152	jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
3153	dump_stack();
3154	return -EIO;
3155	}
3156
3157	if (wbc->sync_mode != WB_SYNC_ALL)
3158	return 0;
3159
3160	return ext3_force_commit(inode->i_sb);
3161	}
3162
3163	/*
3164	* ext3_setattr()
3165	*
3166	* Called from notify_change.
3167	*
3168	* We want to trap VFS attempts to truncate the file as soon as
3169	* possible. In particular, we want to make sure that when the VFS
3170	* shrinks i_size, we put the inode on the orphan list and modify
3171	* i_disksize immediately, so that during the subsequent flushing of
3172	* dirty pages and freeing of disk blocks, we can guarantee that any
3173	* commit will leave the blocks being flushed in an unused state on
3174	* disk. (On recovery, the inode will get truncated and the blocks will
3175	* be freed, so we have a strong guarantee that no future commit will
3176	* leave these blocks visible to the user.)
3177	*
3178	* Called with inode->sem down.
3179	*/
3180	int ext3_setattr(struct dentry dentry, struct iattr attr)
3181	{
3182	struct inode *inode = dentry->d_inode;
3183	int error, rc = 0;
3184	const unsigned int ia_valid = attr->ia_valid;
3185
3186	error = inode_change_ok(inode, attr);
3187	if (error)
3188	return error;
3189
3190	if (is_quota_modification(inode, attr))
3191	dquot_initialize(inode);
3192	if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) \|\|
3193	(ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
3194	handle_t *handle;
3195
3196	/* (user+group)*(old+new) structure, inode write (sb,
3197	* inode block, ? - but truncate inode update has it) */
3198	handle = ext3_journal_start(inode, EXT3_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+
3199	EXT3_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)+3);
3200	if (IS_ERR(handle)) {
3201	error = PTR_ERR(handle);
3202	goto err_out;
3203	}
3204	error = dquot_transfer(inode, attr);
3205	if (error) {
3206	ext3_journal_stop(handle);
3207	return error;
3208	}
3209	/* Update corresponding info in inode so that everything is in
3210	* one transaction */
3211	if (attr->ia_valid & ATTR_UID)
3212	inode->i_uid = attr->ia_uid;
3213	if (attr->ia_valid & ATTR_GID)
3214	inode->i_gid = attr->ia_gid;
3215	error = ext3_mark_inode_dirty(handle, inode);
3216	ext3_journal_stop(handle);
3217	}
3218
3219	if (S_ISREG(inode->i_mode) &&
3220	attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
3221	handle_t *handle;
3222
3223	handle = ext3_journal_start(inode, 3);
3224	if (IS_ERR(handle)) {
3225	error = PTR_ERR(handle);
3226	goto err_out;
3227	}
3228
3229	error = ext3_orphan_add(handle, inode);
3230	EXT3_I(inode)->i_disksize = attr->ia_size;
3231	rc = ext3_mark_inode_dirty(handle, inode);
3232	if (!error)
3233	error = rc;
3234	ext3_journal_stop(handle);
3235	}
3236
3237	if ((attr->ia_valid & ATTR_SIZE) &&
3238	attr->ia_size != i_size_read(inode)) {
3239	rc = vmtruncate(inode, attr->ia_size);
3240	if (rc)
3241	goto err_out;
3242	}
3243
3244	setattr_copy(inode, attr);
3245	mark_inode_dirty(inode);
3246
3247	if (ia_valid & ATTR_MODE)
3248	rc = ext3_acl_chmod(inode);
3249
3250	err_out:
3251	ext3_std_error(inode->i_sb, error);
3252	if (!error)
3253	error = rc;
3254	return error;
3255	}
3256
3257
3258	/*
3259	* How many blocks doth make a writepage()?
3260	*
3261	* With N blocks per page, it may be:
3262	* N data blocks
3263	* 2 indirect block
3264	* 2 dindirect
3265	* 1 tindirect
3266	* N+5 bitmap blocks (from the above)
3267	* N+5 group descriptor summary blocks
3268	* 1 inode block
3269	* 1 superblock.
3270	* 2 * EXT3_SINGLEDATA_TRANS_BLOCKS for the quote files
3271	*
3272	* 3 * (N + 5) + 2 + 2 * EXT3_SINGLEDATA_TRANS_BLOCKS
3273	*
3274	* With ordered or writeback data it's the same, less the N data blocks.
3275	*
3276	* If the inode's direct blocks can hold an integral number of pages then a
3277	* page cannot straddle two indirect blocks, and we can only touch one indirect
3278	* and dindirect block, and the "5" above becomes "3".
3279	*
3280	* This still overestimates under most circumstances. If we were to pass the
3281	* start and end offsets in here as well we could do block_to_path() on each
3282	* block and work out the exact number of indirects which are touched. Pah.
3283	*/
3284
3285	static int ext3_writepage_trans_blocks(struct inode *inode)
3286	{
3287	int bpp = ext3_journal_blocks_per_page(inode);
3288	int indirects = (EXT3_NDIR_BLOCKS % bpp) ? 5 : 3;
3289	int ret;
3290
3291	if (ext3_should_journal_data(inode))
3292	ret = 3 * (bpp + indirects) + 2;
3293	else
3294	ret = 2 * (bpp + indirects) + indirects + 2;
3295
3296	#ifdef CONFIG_QUOTA
3297	/* We know that structure was already allocated during dquot_initialize so
3298	* we will be updating only the data blocks + inodes */
3299	ret += EXT3_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
3300	#endif
3301
3302	return ret;
3303	}
3304
3305	/*
3306	* The caller must have previously called ext3_reserve_inode_write().
3307	* Give this, we know that the caller already has write access to iloc->bh.
3308	*/
3309	int ext3_mark_iloc_dirty(handle_t *handle,
3310	struct inode inode, struct ext3_iloc iloc)
3311	{
3312	int err = 0;
3313
3314	/* the do_update_inode consumes one bh->b_count */
3315	get_bh(iloc->bh);
3316
3317	/* ext3_do_update_inode() does journal_dirty_metadata */
3318	err = ext3_do_update_inode(handle, inode, iloc);
3319	put_bh(iloc->bh);
3320	return err;
3321	}
3322
3323	/*
3324	* On success, We end up with an outstanding reference count against
3325	* iloc->bh. This _must_ be cleaned up later.
3326	*/
3327
3328	int
3329	ext3_reserve_inode_write(handle_t handle, struct inode inode,
3330	struct ext3_iloc *iloc)
3331	{
3332	int err = 0;
3333	if (handle) {
3334	err = ext3_get_inode_loc(inode, iloc);
3335	if (!err) {
3336	BUFFER_TRACE(iloc->bh, "get_write_access");
3337	err = ext3_journal_get_write_access(handle, iloc->bh);
3338	if (err) {
3339	brelse(iloc->bh);
3340	iloc->bh = NULL;
3341	}
3342	}
3343	}
3344	ext3_std_error(inode->i_sb, err);
3345	return err;
3346	}
3347
3348	/*
3349	* What we do here is to mark the in-core inode as clean with respect to inode
3350	* dirtiness (it may still be data-dirty).
3351	* This means that the in-core inode may be reaped by prune_icache
3352	* without having to perform any I/O. This is a very good thing,
3353	* because any task may call prune_icache - even ones which
3354	* have a transaction open against a different journal.
3355	*
3356	* Is this cheating? Not really. Sure, we haven't written the
3357	* inode out, but prune_icache isn't a user-visible syncing function.
3358	* Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
3359	* we start and wait on commits.
3360	*
3361	* Is this efficient/effective? Well, we're being nice to the system
3362	* by cleaning up our inodes proactively so they can be reaped
3363	* without I/O. But we are potentially leaving up to five seconds'
3364	* worth of inodes floating about which prune_icache wants us to
3365	* write out. One way to fix that would be to get prune_icache()
3366	* to do a write_super() to free up some memory. It has the desired
3367	* effect.
3368	*/
3369	int ext3_mark_inode_dirty(handle_t handle, struct inode inode)
3370	{
3371	struct ext3_iloc iloc;
3372	int err;
3373
3374	might_sleep();
3375	err = ext3_reserve_inode_write(handle, inode, &iloc);
3376	if (!err)
3377	err = ext3_mark_iloc_dirty(handle, inode, &iloc);
3378	return err;
3379	}
3380
3381	/*
3382	* ext3_dirty_inode() is called from __mark_inode_dirty()
3383	*
3384	* We're really interested in the case where a file is being extended.
3385	* i_size has been changed by generic_commit_write() and we thus need
3386	* to include the updated inode in the current transaction.
3387	*
3388	* Also, dquot_alloc_space() will always dirty the inode when blocks
3389	* are allocated to the file.
3390	*
3391	* If the inode is marked synchronous, we don't honour that here - doing
3392	* so would cause a commit on atime updates, which we don't bother doing.
3393	* We handle synchronous inodes at the highest possible level.
3394	*/
3395	void ext3_dirty_inode(struct inode *inode, int flags)
3396	{
3397	handle_t *current_handle = ext3_journal_current_handle();
3398	handle_t *handle;
3399
3400	handle = ext3_journal_start(inode, 2);
3401	if (IS_ERR(handle))
3402	goto out;
3403	if (current_handle &&
3404	current_handle->h_transaction != handle->h_transaction) {
3405	/* This task has a transaction open against a different fs */
3406	printk(KERN_EMERG "%s: transactions do not match!\n",
3407	__func__);
3408	} else {
3409	jbd_debug(5, "marking dirty. outer handle=%p\n",
3410	current_handle);
3411	ext3_mark_inode_dirty(handle, inode);
3412	}
3413	ext3_journal_stop(handle);
3414	out:
3415	return;
3416	}
3417
3418	#if 0
3419	/*
3420	* Bind an inode's backing buffer_head into this transaction, to prevent
3421	* it from being flushed to disk early. Unlike
3422	* ext3_reserve_inode_write, this leaves behind no bh reference and
3423	* returns no iloc structure, so the caller needs to repeat the iloc
3424	* lookup to mark the inode dirty later.
3425	*/
3426	static int ext3_pin_inode(handle_t handle, struct inode inode)
3427	{
3428	struct ext3_iloc iloc;
3429
3430	int err = 0;
3431	if (handle) {
3432	err = ext3_get_inode_loc(inode, &iloc);
3433	if (!err) {
3434	BUFFER_TRACE(iloc.bh, "get_write_access");
3435	err = journal_get_write_access(handle, iloc.bh);
3436	if (!err)
3437	err = ext3_journal_dirty_metadata(handle,
3438	iloc.bh);
3439	brelse(iloc.bh);
3440	}
3441	}
3442	ext3_std_error(inode->i_sb, err);
3443	return err;
3444	}
3445	#endif
3446
3447	int ext3_change_inode_journal_flag(struct inode *inode, int val)
3448	{
3449	journal_t *journal;
3450	handle_t *handle;
3451	int err;
3452
3453	/*
3454	* We have to be very careful here: changing a data block's
3455	* journaling status dynamically is dangerous. If we write a
3456	* data block to the journal, change the status and then delete
3457	* that block, we risk forgetting to revoke the old log record
3458	* from the journal and so a subsequent replay can corrupt data.
3459	* So, first we make sure that the journal is empty and that
3460	* nobody is changing anything.
3461	*/
3462
3463	journal = EXT3_JOURNAL(inode);
3464	if (is_journal_aborted(journal))
3465	return -EROFS;
3466
3467	journal_lock_updates(journal);
3468	journal_flush(journal);
3469
3470	/*
3471	* OK, there are no updates running now, and all cached data is
3472	* synced to disk. We are now in a completely consistent state
3473	* which doesn't have anything in the journal, and we know that
3474	* no filesystem updates are running, so it is safe to modify
3475	* the inode's in-core data-journaling state flag now.
3476	*/
3477
3478	if (val)
3479	EXT3_I(inode)->i_flags \|= EXT3_JOURNAL_DATA_FL;
3480	else
3481	EXT3_I(inode)->i_flags &= ~EXT3_JOURNAL_DATA_FL;
3482	ext3_set_aops(inode);
3483
3484	journal_unlock_updates(journal);
3485
3486	/* Finally we can mark the inode as dirty. */
3487
3488	handle = ext3_journal_start(inode, 1);
3489	if (IS_ERR(handle))
3490	return PTR_ERR(handle);
3491
3492	err = ext3_mark_inode_dirty(handle, inode);
3493	handle->h_sync = 1;
3494	ext3_journal_stop(handle);
3495	ext3_std_error(inode->i_sb, err);
3496
3497	return err;
3498	}
3499

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