Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c99d1e6e authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

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: 86f0afd4
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent 36de9286

fs/ext4/mballoc.c

+5 −0
Original line number Diff line number Diff line
@@ -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)