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From: Greg KH on 30 Jul 2010 13:40
2.6.32-stable review patch. If anyone has any objections, please let us know.

------------------

commit b90f687018e6d6c77d981b09203780f7001407e5 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(a)mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
---
fs/ext4/mballoc.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2537,6 +2537,17 @@ static void release_blocks_on_commit(jou
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(jou
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);
}


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Prev: [123/165] ext4: Prevent creation of files larger than RLIMIT_FSIZE using fallocate
Next: [107/165] ext4: Fix buffer head leaks after calls to ext4_get_inode_loc()