Commit 08b9d6b9 authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Greg Kroah-Hartman

ext4: fix BUG_ON in mb_free_blocks()

commit c99d1e6e 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: 86f0afd4Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 35df08d6
...@@ -1412,6 +1412,8 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b, ...@@ -1412,6 +1412,8 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
int last = first + count - 1; int last = first + count - 1;
struct super_block *sb = e4b->bd_sb; struct super_block *sb = e4b->bd_sb;
if (WARN_ON(count == 0))
return;
BUG_ON(last >= (sb->s_blocksize << 3)); BUG_ON(last >= (sb->s_blocksize << 3));
assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group)); assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group));
/* Don't bother if the block group is corrupt. */ /* Don't bother if the block group is corrupt. */
...@@ -3220,6 +3222,8 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac) ...@@ -3220,6 +3222,8 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
int err; int err;
if (pa == NULL) { 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); err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b);
if (err) { if (err) {
/* /*
...@@ -3234,6 +3238,7 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac) ...@@ -3234,6 +3238,7 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start, mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start,
ac->ac_f_ex.fe_len); ac->ac_f_ex.fe_len);
ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group); ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
ext4_mb_unload_buddy(&e4b);
return; return;
} }
if (pa->pa_type == MB_INODE_PA) if (pa->pa_type == MB_INODE_PA)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment