| From c99d1e6e83b06744c75d9f5e491ed495a7086b7b Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Sat, 23 Aug 2014 17:47:28 -0400 |
| Subject: ext4: fix BUG_ON in mb_free_blocks() |
| |
| From: Theodore Ts'o <tytso@mit.edu> |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/mballoc.c | 5 +++++ |
| 1 file changed, 5 insertions(+) |
| |
| --- a/fs/ext4/mballoc.c |
| +++ b/fs/ext4/mballoc.c |
| @@ -1398,6 +1398,8 @@ static void mb_free_blocks(struct inode |
| 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_block |
| 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_block |
| 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) |