From b90f687018e6d6c77d981b09203780f7001407e5 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 20 Apr 2010 16:51:59 -0400 Subject: [PATCH] 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" --- fs/ext4/mballoc.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 54df209d..e5ab41b 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -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); } -- 2.7.4