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| author | Theodore Ts'o <tytso@mit.edu> | 2014-08-23 17:47:28 -0400 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-09-15 09:39:36 +0200 |
| commit | bbcd86fa91e60af29c3de9a38aa28c314468cc5f (patch) | |
| tree | a7b0a53c714d964566da5ad15003931424bc1847 /fs/ext4 | |
| parent | 66acfbf79cf6f97b0935a5830703166fae3104c1 (diff) | |
| download | lwn-bbcd86fa91e60af29c3de9a38aa28c314468cc5f.tar.gz lwn-bbcd86fa91e60af29c3de9a38aa28c314468cc5f.zip | |
ext4: fix BUG_ON in mb_free_blocks()
commit c99d1e6e83b06744c75d9f5e491ed495a7086b7b upstream.
If we suffer a block allocation failure (for example due to a memory
allocation failure), it's possible that we will call
ext4_discard_allocated_blocks() before we've actually allocated any
blocks. In that case, fe_len and fe_start in ac->ac_f_ex will still
be zero, and this will result in mb_free_blocks(inode, e4b, 0, 0)
triggering the BUG_ON on mb_free_blocks():
BUG_ON(last >= (sb->s_blocksize << 3));
Fix this by bailing out of ext4_discard_allocated_blocks() if fs_len
is zero.
Also fix a missing ext4_mb_unload_buddy() call in
ext4_discard_allocated_blocks().
Google-Bug-Id: 16844242
Fixes: 86f0afd463215fc3e58020493482faa4ac3a4d69
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/mballoc.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 795d5afc1479..242226a87be7 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1398,6 +1398,8 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b, int last = first + count - 1; struct super_block *sb = e4b->bd_sb; + if (WARN_ON(count == 0)) + return; BUG_ON(last >= (sb->s_blocksize << 3)); assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group)); /* Don't bother if the block group is corrupt. */ @@ -3200,6 +3202,8 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac) int err; if (pa == NULL) { + if (ac->ac_f_ex.fe_len == 0) + return; err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b); if (err) { /* @@ -3214,6 +3218,7 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac) mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start, ac->ac_f_ex.fe_len); ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group); + ext4_mb_unload_buddy(&e4b); return; } if (pa->pa_type == MB_INODE_PA) |