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

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>
This commit is contained in:
Theodore Ts'o 2010-04-20 16:51:59 -04:00
parent fd2dd9fbaf
commit b90f687018
1 changed files with 11 additions and 10 deletions
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21
fs/ext4/mballoc.c
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@ -2534,6 +2534,17 @@ 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);
@ -2555,16 +2566,6 @@ 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;
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);
}
kmem_cache_free(ext4_free_ext_cachep, entry);
ext4_mb_release_desc(&e4b);
}