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ext4: Issue the discard operation *before* releasing the blocks to be reused

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commit b90f687018 upstream (as of v2.6.34-rc6)

Otherwise, we can end up having data corruption because the blocks
could get reused and then discarded!

https://bugzilla.kernel.org/show_bug.cgi?id=15579

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Theodore Ts'o 2010-05-30 22:49:42 -04:00 committed by Greg Kroah-Hartman
parent adaf14bef6
commit 43a1669ae0
1 changed files with 11 additions and 13 deletions
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24
fs/ext4/mballoc.c
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@ -2537,6 +2537,17 @@ static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
mb_debug(1, "gonna free %u blocks in group %u (0x%p):",
entry->count, entry->group, entry);
if (test_opt(sb, DISCARD)) {
ext4_fsblk_t discard_block;
discard_block = entry->start_blk +
ext4_group_first_block_no(sb, entry->group);
trace_ext4_discard_blocks(sb,
(unsigned long long)discard_block,
entry->count);
sb_issue_discard(sb, discard_block, entry->count);
}
err = ext4_mb_load_buddy(sb, entry->group, &e4b);
/* we expect to find existing buddy because it's pinned */
BUG_ON(err != 0);
@ -2558,19 +2569,6 @@ static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
page_cache_release(e4b.bd_bitmap_page);
}
ext4_unlock_group(sb, entry->group);
if (test_opt(sb, DISCARD)) {
ext4_fsblk_t discard_block;
struct ext4_super_block *es = EXT4_SB(sb)->s_es;
discard_block = (ext4_fsblk_t)entry->group *
EXT4_BLOCKS_PER_GROUP(sb)
+ entry->start_blk
+ le32_to_cpu(es->s_first_data_block);
trace_ext4_discard_blocks(sb,
(unsigned long long)discard_block,
entry->count);
sb_issue_discard(sb, discard_block, entry->count);
}
kmem_cache_free(ext4_free_ext_cachep, entry);
ext4_mb_release_desc(&e4b);
}