Root/fs/ext4/balloc.c

1/*
2 * linux/fs/ext4/balloc.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 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10 * Big-endian to little-endian byte-swapping/bitmaps by
11 * David S. Miller (davem@caip.rutgers.edu), 1995
12 */
13
14#include <linux/time.h>
15#include <linux/capability.h>
16#include <linux/fs.h>
17#include <linux/jbd2.h>
18#include <linux/quotaops.h>
19#include <linux/buffer_head.h>
20#include "ext4.h"
21#include "ext4_jbd2.h"
22#include "mballoc.h"
23
24/*
25 * balloc.c contains the blocks allocation and deallocation routines
26 */
27
28/*
29 * Calculate the block group number and offset, given a block number
30 */
31void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
32        ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
33{
34    struct ext4_super_block *es = EXT4_SB(sb)->s_es;
35    ext4_grpblk_t offset;
36
37    blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
38    offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
39    if (offsetp)
40        *offsetp = offset;
41    if (blockgrpp)
42        *blockgrpp = blocknr;
43
44}
45
46static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
47            ext4_group_t block_group)
48{
49    ext4_group_t actual_group;
50    ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
51    if (actual_group == block_group)
52        return 1;
53    return 0;
54}
55
56static int ext4_group_used_meta_blocks(struct super_block *sb,
57                       ext4_group_t block_group,
58                       struct ext4_group_desc *gdp)
59{
60    ext4_fsblk_t tmp;
61    struct ext4_sb_info *sbi = EXT4_SB(sb);
62    /* block bitmap, inode bitmap, and inode table blocks */
63    int used_blocks = sbi->s_itb_per_group + 2;
64
65    if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
66        if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
67                    block_group))
68            used_blocks--;
69
70        if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
71                    block_group))
72            used_blocks--;
73
74        tmp = ext4_inode_table(sb, gdp);
75        for (; tmp < ext4_inode_table(sb, gdp) +
76                sbi->s_itb_per_group; tmp++) {
77            if (!ext4_block_in_group(sb, tmp, block_group))
78                used_blocks -= 1;
79        }
80    }
81    return used_blocks;
82}
83
84/* Initializes an uninitialized block bitmap if given, and returns the
85 * number of blocks free in the group. */
86unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
87         ext4_group_t block_group, struct ext4_group_desc *gdp)
88{
89    int bit, bit_max;
90    ext4_group_t ngroups = ext4_get_groups_count(sb);
91    unsigned free_blocks, group_blocks;
92    struct ext4_sb_info *sbi = EXT4_SB(sb);
93
94    if (bh) {
95        J_ASSERT_BH(bh, buffer_locked(bh));
96
97        /* If checksum is bad mark all blocks used to prevent allocation
98         * essentially implementing a per-group read-only flag. */
99        if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
100            ext4_error(sb, __func__,
101                  "Checksum bad for group %u", block_group);
102            ext4_free_blks_set(sb, gdp, 0);
103            ext4_free_inodes_set(sb, gdp, 0);
104            ext4_itable_unused_set(sb, gdp, 0);
105            memset(bh->b_data, 0xff, sb->s_blocksize);
106            return 0;
107        }
108        memset(bh->b_data, 0, sb->s_blocksize);
109    }
110
111    /* Check for superblock and gdt backups in this group */
112    bit_max = ext4_bg_has_super(sb, block_group);
113
114    if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
115        block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
116              sbi->s_desc_per_block) {
117        if (bit_max) {
118            bit_max += ext4_bg_num_gdb(sb, block_group);
119            bit_max +=
120                le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
121        }
122    } else { /* For META_BG_BLOCK_GROUPS */
123        bit_max += ext4_bg_num_gdb(sb, block_group);
124    }
125
126    if (block_group == ngroups - 1) {
127        /*
128         * Even though mke2fs always initialize first and last group
129         * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
130         * to make sure we calculate the right free blocks
131         */
132        group_blocks = ext4_blocks_count(sbi->s_es) -
133            le32_to_cpu(sbi->s_es->s_first_data_block) -
134            (EXT4_BLOCKS_PER_GROUP(sb) * (ngroups - 1));
135    } else {
136        group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
137    }
138
139    free_blocks = group_blocks - bit_max;
140
141    if (bh) {
142        ext4_fsblk_t start, tmp;
143        int flex_bg = 0;
144
145        for (bit = 0; bit < bit_max; bit++)
146            ext4_set_bit(bit, bh->b_data);
147
148        start = ext4_group_first_block_no(sb, block_group);
149
150        if (EXT4_HAS_INCOMPAT_FEATURE(sb,
151                          EXT4_FEATURE_INCOMPAT_FLEX_BG))
152            flex_bg = 1;
153
154        /* Set bits for block and inode bitmaps, and inode table */
155        tmp = ext4_block_bitmap(sb, gdp);
156        if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
157            ext4_set_bit(tmp - start, bh->b_data);
158
159        tmp = ext4_inode_bitmap(sb, gdp);
160        if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
161            ext4_set_bit(tmp - start, bh->b_data);
162
163        tmp = ext4_inode_table(sb, gdp);
164        for (; tmp < ext4_inode_table(sb, gdp) +
165                sbi->s_itb_per_group; tmp++) {
166            if (!flex_bg ||
167                ext4_block_in_group(sb, tmp, block_group))
168                ext4_set_bit(tmp - start, bh->b_data);
169        }
170        /*
171         * Also if the number of blocks within the group is
172         * less than the blocksize * 8 ( which is the size
173         * of bitmap ), set rest of the block bitmap to 1
174         */
175        mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
176    }
177    return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
178}
179
180
181/*
182 * The free blocks are managed by bitmaps. A file system contains several
183 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
184 * block for inodes, N blocks for the inode table and data blocks.
185 *
186 * The file system contains group descriptors which are located after the
187 * super block. Each descriptor contains the number of the bitmap block and
188 * the free blocks count in the block. The descriptors are loaded in memory
189 * when a file system is mounted (see ext4_fill_super).
190 */
191
192
193#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
194
195/**
196 * ext4_get_group_desc() -- load group descriptor from disk
197 * @sb: super block
198 * @block_group: given block group
199 * @bh: pointer to the buffer head to store the block
200 * group descriptor
201 */
202struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
203                         ext4_group_t block_group,
204                         struct buffer_head **bh)
205{
206    unsigned int group_desc;
207    unsigned int offset;
208    ext4_group_t ngroups = ext4_get_groups_count(sb);
209    struct ext4_group_desc *desc;
210    struct ext4_sb_info *sbi = EXT4_SB(sb);
211
212    if (block_group >= ngroups) {
213        ext4_error(sb, "ext4_get_group_desc",
214               "block_group >= groups_count - "
215               "block_group = %u, groups_count = %u",
216               block_group, ngroups);
217
218        return NULL;
219    }
220
221    group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
222    offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
223    if (!sbi->s_group_desc[group_desc]) {
224        ext4_error(sb, "ext4_get_group_desc",
225               "Group descriptor not loaded - "
226               "block_group = %u, group_desc = %u, desc = %u",
227               block_group, group_desc, offset);
228        return NULL;
229    }
230
231    desc = (struct ext4_group_desc *)(
232        (__u8 *)sbi->s_group_desc[group_desc]->b_data +
233        offset * EXT4_DESC_SIZE(sb));
234    if (bh)
235        *bh = sbi->s_group_desc[group_desc];
236    return desc;
237}
238
239static int ext4_valid_block_bitmap(struct super_block *sb,
240                    struct ext4_group_desc *desc,
241                    unsigned int block_group,
242                    struct buffer_head *bh)
243{
244    ext4_grpblk_t offset;
245    ext4_grpblk_t next_zero_bit;
246    ext4_fsblk_t bitmap_blk;
247    ext4_fsblk_t group_first_block;
248
249    if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
250        /* with FLEX_BG, the inode/block bitmaps and itable
251         * blocks may not be in the group at all
252         * so the bitmap validation will be skipped for those groups
253         * or it has to also read the block group where the bitmaps
254         * are located to verify they are set.
255         */
256        return 1;
257    }
258    group_first_block = ext4_group_first_block_no(sb, block_group);
259
260    /* check whether block bitmap block number is set */
261    bitmap_blk = ext4_block_bitmap(sb, desc);
262    offset = bitmap_blk - group_first_block;
263    if (!ext4_test_bit(offset, bh->b_data))
264        /* bad block bitmap */
265        goto err_out;
266
267    /* check whether the inode bitmap block number is set */
268    bitmap_blk = ext4_inode_bitmap(sb, desc);
269    offset = bitmap_blk - group_first_block;
270    if (!ext4_test_bit(offset, bh->b_data))
271        /* bad block bitmap */
272        goto err_out;
273
274    /* check whether the inode table block number is set */
275    bitmap_blk = ext4_inode_table(sb, desc);
276    offset = bitmap_blk - group_first_block;
277    next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
278                offset + EXT4_SB(sb)->s_itb_per_group,
279                offset);
280    if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
281        /* good bitmap for inode tables */
282        return 1;
283
284err_out:
285    ext4_error(sb, __func__,
286            "Invalid block bitmap - "
287            "block_group = %d, block = %llu",
288            block_group, bitmap_blk);
289    return 0;
290}
291/**
292 * ext4_read_block_bitmap()
293 * @sb: super block
294 * @block_group: given block group
295 *
296 * Read the bitmap for a given block_group,and validate the
297 * bits for block/inode/inode tables are set in the bitmaps
298 *
299 * Return buffer_head on success or NULL in case of failure.
300 */
301struct buffer_head *
302ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
303{
304    struct ext4_group_desc *desc;
305    struct buffer_head *bh = NULL;
306    ext4_fsblk_t bitmap_blk;
307
308    desc = ext4_get_group_desc(sb, block_group, NULL);
309    if (!desc)
310        return NULL;
311    bitmap_blk = ext4_block_bitmap(sb, desc);
312    bh = sb_getblk(sb, bitmap_blk);
313    if (unlikely(!bh)) {
314        ext4_error(sb, __func__,
315                "Cannot read block bitmap - "
316                "block_group = %u, block_bitmap = %llu",
317                block_group, bitmap_blk);
318        return NULL;
319    }
320
321    if (bitmap_uptodate(bh))
322        return bh;
323
324    lock_buffer(bh);
325    if (bitmap_uptodate(bh)) {
326        unlock_buffer(bh);
327        return bh;
328    }
329    ext4_lock_group(sb, block_group);
330    if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
331        ext4_init_block_bitmap(sb, bh, block_group, desc);
332        set_bitmap_uptodate(bh);
333        set_buffer_uptodate(bh);
334        ext4_unlock_group(sb, block_group);
335        unlock_buffer(bh);
336        return bh;
337    }
338    ext4_unlock_group(sb, block_group);
339    if (buffer_uptodate(bh)) {
340        /*
341         * if not uninit if bh is uptodate,
342         * bitmap is also uptodate
343         */
344        set_bitmap_uptodate(bh);
345        unlock_buffer(bh);
346        return bh;
347    }
348    /*
349     * submit the buffer_head for read. We can
350     * safely mark the bitmap as uptodate now.
351     * We do it here so the bitmap uptodate bit
352     * get set with buffer lock held.
353     */
354    set_bitmap_uptodate(bh);
355    if (bh_submit_read(bh) < 0) {
356        put_bh(bh);
357        ext4_error(sb, __func__,
358                "Cannot read block bitmap - "
359                "block_group = %u, block_bitmap = %llu",
360                block_group, bitmap_blk);
361        return NULL;
362    }
363    ext4_valid_block_bitmap(sb, desc, block_group, bh);
364    /*
365     * file system mounted not to panic on error,
366     * continue with corrupt bitmap
367     */
368    return bh;
369}
370
371/**
372 * ext4_add_groupblocks() -- Add given blocks to an existing group
373 * @handle: handle to this transaction
374 * @sb: super block
375 * @block: start physcial block to add to the block group
376 * @count: number of blocks to free
377 *
378 * This marks the blocks as free in the bitmap. We ask the
379 * mballoc to reload the buddy after this by setting group
380 * EXT4_GROUP_INFO_NEED_INIT_BIT flag
381 */
382void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
383             ext4_fsblk_t block, unsigned long count)
384{
385    struct buffer_head *bitmap_bh = NULL;
386    struct buffer_head *gd_bh;
387    ext4_group_t block_group;
388    ext4_grpblk_t bit;
389    unsigned int i;
390    struct ext4_group_desc *desc;
391    struct ext4_super_block *es;
392    struct ext4_sb_info *sbi;
393    int err = 0, ret, blk_free_count;
394    ext4_grpblk_t blocks_freed;
395    struct ext4_group_info *grp;
396
397    sbi = EXT4_SB(sb);
398    es = sbi->s_es;
399    ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
400
401    ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
402    grp = ext4_get_group_info(sb, block_group);
403    /*
404     * Check to see if we are freeing blocks across a group
405     * boundary.
406     */
407    if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
408        goto error_return;
409    }
410    bitmap_bh = ext4_read_block_bitmap(sb, block_group);
411    if (!bitmap_bh)
412        goto error_return;
413    desc = ext4_get_group_desc(sb, block_group, &gd_bh);
414    if (!desc)
415        goto error_return;
416
417    if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
418        in_range(ext4_inode_bitmap(sb, desc), block, count) ||
419        in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
420        in_range(block + count - 1, ext4_inode_table(sb, desc),
421             sbi->s_itb_per_group)) {
422        ext4_error(sb, __func__,
423               "Adding blocks in system zones - "
424               "Block = %llu, count = %lu",
425               block, count);
426        goto error_return;
427    }
428
429    /*
430     * We are about to add blocks to the bitmap,
431     * so we need undo access.
432     */
433    BUFFER_TRACE(bitmap_bh, "getting undo access");
434    err = ext4_journal_get_undo_access(handle, bitmap_bh);
435    if (err)
436        goto error_return;
437
438    /*
439     * We are about to modify some metadata. Call the journal APIs
440     * to unshare ->b_data if a currently-committing transaction is
441     * using it
442     */
443    BUFFER_TRACE(gd_bh, "get_write_access");
444    err = ext4_journal_get_write_access(handle, gd_bh);
445    if (err)
446        goto error_return;
447    /*
448     * make sure we don't allow a parallel init on other groups in the
449     * same buddy cache
450     */
451    down_write(&grp->alloc_sem);
452    for (i = 0, blocks_freed = 0; i < count; i++) {
453        BUFFER_TRACE(bitmap_bh, "clear bit");
454        if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
455                        bit + i, bitmap_bh->b_data)) {
456            ext4_error(sb, __func__,
457                   "bit already cleared for block %llu",
458                   (ext4_fsblk_t)(block + i));
459            BUFFER_TRACE(bitmap_bh, "bit already cleared");
460        } else {
461            blocks_freed++;
462        }
463    }
464    ext4_lock_group(sb, block_group);
465    blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
466    ext4_free_blks_set(sb, desc, blk_free_count);
467    desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
468    ext4_unlock_group(sb, block_group);
469    percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
470
471    if (sbi->s_log_groups_per_flex) {
472        ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
473        atomic_add(blocks_freed,
474               &sbi->s_flex_groups[flex_group].free_blocks);
475    }
476    /*
477     * request to reload the buddy with the
478     * new bitmap information
479     */
480    set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
481    ext4_mb_update_group_info(grp, blocks_freed);
482    up_write(&grp->alloc_sem);
483
484    /* We dirtied the bitmap block */
485    BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
486    err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
487
488    /* And the group descriptor block */
489    BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
490    ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
491    if (!err)
492        err = ret;
493    sb->s_dirt = 1;
494
495error_return:
496    brelse(bitmap_bh);
497    ext4_std_error(sb, err);
498    return;
499}
500
501/**
502 * ext4_free_blocks() -- Free given blocks and update quota
503 * @handle: handle for this transaction
504 * @inode: inode
505 * @block: start physical block to free
506 * @count: number of blocks to count
507 * @metadata: Are these metadata blocks
508 */
509void ext4_free_blocks(handle_t *handle, struct inode *inode,
510            ext4_fsblk_t block, unsigned long count,
511            int metadata)
512{
513    struct super_block *sb;
514    unsigned long dquot_freed_blocks;
515
516    /* this isn't the right place to decide whether block is metadata
517     * inode.c/extents.c knows better, but for safety ... */
518    if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
519        metadata = 1;
520
521    /* We need to make sure we don't reuse
522     * block released untill the transaction commit.
523     * writeback mode have weak data consistency so
524     * don't force data as metadata when freeing block
525     * for writeback mode.
526     */
527    if (metadata == 0 && !ext4_should_writeback_data(inode))
528        metadata = 1;
529
530    sb = inode->i_sb;
531
532    ext4_mb_free_blocks(handle, inode, block, count,
533                metadata, &dquot_freed_blocks);
534    if (dquot_freed_blocks)
535        vfs_dq_free_block(inode, dquot_freed_blocks);
536    return;
537}
538
539/**
540 * ext4_has_free_blocks()
541 * @sbi: in-core super block structure.
542 * @nblocks: number of needed blocks
543 *
544 * Check if filesystem has nblocks free & available for allocation.
545 * On success return 1, return 0 on failure.
546 */
547int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
548{
549    s64 free_blocks, dirty_blocks, root_blocks;
550    struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
551    struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
552
553    free_blocks = percpu_counter_read_positive(fbc);
554    dirty_blocks = percpu_counter_read_positive(dbc);
555    root_blocks = ext4_r_blocks_count(sbi->s_es);
556
557    if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
558                        EXT4_FREEBLOCKS_WATERMARK) {
559        free_blocks = percpu_counter_sum_positive(fbc);
560        dirty_blocks = percpu_counter_sum_positive(dbc);
561        if (dirty_blocks < 0) {
562            printk(KERN_CRIT "Dirty block accounting "
563                    "went wrong %lld\n",
564                    (long long)dirty_blocks);
565        }
566    }
567    /* Check whether we have space after
568     * accounting for current dirty blocks & root reserved blocks.
569     */
570    if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
571        return 1;
572
573    /* Hm, nope. Are (enough) root reserved blocks available? */
574    if (sbi->s_resuid == current_fsuid() ||
575        ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
576        capable(CAP_SYS_RESOURCE)) {
577        if (free_blocks >= (nblocks + dirty_blocks))
578            return 1;
579    }
580
581    return 0;
582}
583
584int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
585                        s64 nblocks)
586{
587    if (ext4_has_free_blocks(sbi, nblocks)) {
588        percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
589        return 0;
590    } else
591        return -ENOSPC;
592}
593
594/**
595 * ext4_should_retry_alloc()
596 * @sb: super block
597 * @retries number of attemps has been made
598 *
599 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
600 * it is profitable to retry the operation, this function will wait
601 * for the current or commiting transaction to complete, and then
602 * return TRUE.
603 *
604 * if the total number of retries exceed three times, return FALSE.
605 */
606int ext4_should_retry_alloc(struct super_block *sb, int *retries)
607{
608    if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
609        (*retries)++ > 3 ||
610        !EXT4_SB(sb)->s_journal)
611        return 0;
612
613    jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
614
615    return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
616}
617
618/*
619 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
620 *
621 * @handle: handle to this transaction
622 * @inode: file inode
623 * @goal: given target block(filesystem wide)
624 * @count: pointer to total number of blocks needed
625 * @errp: error code
626 *
627 * Return 1st allocated block number on success, *count stores total account
628 * error stores in errp pointer
629 */
630ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
631        ext4_fsblk_t goal, unsigned long *count, int *errp)
632{
633    struct ext4_allocation_request ar;
634    ext4_fsblk_t ret;
635
636    memset(&ar, 0, sizeof(ar));
637    /* Fill with neighbour allocated blocks */
638    ar.inode = inode;
639    ar.goal = goal;
640    ar.len = count ? *count : 1;
641
642    ret = ext4_mb_new_blocks(handle, &ar, errp);
643    if (count)
644        *count = ar.len;
645
646    /*
647     * Account for the allocated meta blocks
648     */
649    if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
650        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
651        EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
652        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
653    }
654    return ret;
655}
656
657/**
658 * ext4_count_free_blocks() -- count filesystem free blocks
659 * @sb: superblock
660 *
661 * Adds up the number of free blocks from each block group.
662 */
663ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
664{
665    ext4_fsblk_t desc_count;
666    struct ext4_group_desc *gdp;
667    ext4_group_t i;
668    ext4_group_t ngroups = ext4_get_groups_count(sb);
669#ifdef EXT4FS_DEBUG
670    struct ext4_super_block *es;
671    ext4_fsblk_t bitmap_count;
672    unsigned int x;
673    struct buffer_head *bitmap_bh = NULL;
674
675    es = EXT4_SB(sb)->s_es;
676    desc_count = 0;
677    bitmap_count = 0;
678    gdp = NULL;
679
680    for (i = 0; i < ngroups; i++) {
681        gdp = ext4_get_group_desc(sb, i, NULL);
682        if (!gdp)
683            continue;
684        desc_count += ext4_free_blks_count(sb, gdp);
685        brelse(bitmap_bh);
686        bitmap_bh = ext4_read_block_bitmap(sb, i);
687        if (bitmap_bh == NULL)
688            continue;
689
690        x = ext4_count_free(bitmap_bh, sb->s_blocksize);
691        printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
692            i, ext4_free_blks_count(sb, gdp), x);
693        bitmap_count += x;
694    }
695    brelse(bitmap_bh);
696    printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
697        ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
698           desc_count, bitmap_count);
699    return bitmap_count;
700#else
701    desc_count = 0;
702    for (i = 0; i < ngroups; i++) {
703        gdp = ext4_get_group_desc(sb, i, NULL);
704        if (!gdp)
705            continue;
706        desc_count += ext4_free_blks_count(sb, gdp);
707    }
708
709    return desc_count;
710#endif
711}
712
713static inline int test_root(ext4_group_t a, int b)
714{
715    int num = b;
716
717    while (a > num)
718        num *= b;
719    return num == a;
720}
721
722static int ext4_group_sparse(ext4_group_t group)
723{
724    if (group <= 1)
725        return 1;
726    if (!(group & 1))
727        return 0;
728    return (test_root(group, 7) || test_root(group, 5) ||
729        test_root(group, 3));
730}
731
732/**
733 * ext4_bg_has_super - number of blocks used by the superblock in group
734 * @sb: superblock for filesystem
735 * @group: group number to check
736 *
737 * Return the number of blocks used by the superblock (primary or backup)
738 * in this group. Currently this will be only 0 or 1.
739 */
740int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
741{
742    if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
743                EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
744            !ext4_group_sparse(group))
745        return 0;
746    return 1;
747}
748
749static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
750                    ext4_group_t group)
751{
752    unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
753    ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
754    ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
755
756    if (group == first || group == first + 1 || group == last)
757        return 1;
758    return 0;
759}
760
761static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
762                    ext4_group_t group)
763{
764    return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
765}
766
767/**
768 * ext4_bg_num_gdb - number of blocks used by the group table in group
769 * @sb: superblock for filesystem
770 * @group: group number to check
771 *
772 * Return the number of blocks used by the group descriptor table
773 * (primary or backup) in this group. In the future there may be a
774 * different number of descriptor blocks in each group.
775 */
776unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
777{
778    unsigned long first_meta_bg =
779            le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
780    unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
781
782    if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
783            metagroup < first_meta_bg)
784        return ext4_bg_num_gdb_nometa(sb, group);
785
786    return ext4_bg_num_gdb_meta(sb,group);
787
788}
789
790

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