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authorTheodore Ts'o <tytso@mit.edu>2014-08-24 01:47:28 +0400
committerTheodore Ts'o <tytso@mit.edu>2014-08-24 01:47:28 +0400
commitc99d1e6e83b06744c75d9f5e491ed495a7086b7b (patch)
tree10700ad60c0dd5cf5f648be2f732a54fd7fe2ae5 /fs/ext4
parent36de928641ee48b2078d3fe9514242aaa2f92013 (diff)
downloadlinux-c99d1e6e83b06744c75d9f5e491ed495a7086b7b.tar.xz
ext4: fix BUG_ON in mb_free_blocks()
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
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/mballoc.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 956027711faf..8b0f9ef517d6 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1412,6 +1412,8 @@ 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. */
@@ -3221,6 +3223,8 @@ 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) {
/*
@@ -3235,6 +3239,7 @@ 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)