Commit 7a4c5de2 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: don't call ext4_error while block group is locked 

While in ext4_validate_block_bitmap(), if an block allocation bitmap
is found to be invalid, we call ext4_error() while the block group is
still locked.  This causes ext4_commit_super() to call a function
which might sleep while in an atomic context.

There's no need to keep the block group locked at this point, so hoist
the ext4_error() call up to ext4_validate_block_bitmap() and release
the block group spinlock before calling ext4_error().

The reported stack trace can be found at:

	http://article.gmane.org/gmane.comp.file-systems.ext4/33731



Reported-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent 7e731bc9

fs/ext4/balloc.c

+37 −25
Original line number Diff line number Diff line
@@ -280,14 +280,18 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, 
	return desc;

}



static int ext4_valid_block_bitmap(struct super_block *sb,

/*

 * Return the block number which was discovered to be invalid, or 0 if

 * the block bitmap is valid.

 */

static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,

					    struct ext4_group_desc *desc,

					    unsigned int block_group,

					    struct buffer_head *bh)

{

	ext4_grpblk_t offset;

	ext4_grpblk_t next_zero_bit;

	ext4_fsblk_t bitmap_blk;

	ext4_fsblk_t blk;

	ext4_fsblk_t group_first_block;



	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
@@ -297,37 +301,33 @@ static int ext4_valid_block_bitmap(struct super_block *sb, 
		 * or it has to also read the block group where the bitmaps

		 * are located to verify they are set.

		 */

		return 1;

		return 0;

	}

	group_first_block = ext4_group_first_block_no(sb, block_group);



	/* check whether block bitmap block number is set */

	bitmap_blk = ext4_block_bitmap(sb, desc);

	offset = bitmap_blk - group_first_block;

	blk = ext4_block_bitmap(sb, desc);

	offset = blk - group_first_block;

	if (!ext4_test_bit(offset, bh->b_data))

		/* bad block bitmap */

		goto err_out;

		return blk;



	/* check whether the inode bitmap block number is set */

	bitmap_blk = ext4_inode_bitmap(sb, desc);

	offset = bitmap_blk - group_first_block;

	blk = ext4_inode_bitmap(sb, desc);

	offset = blk - group_first_block;

	if (!ext4_test_bit(offset, bh->b_data))

		/* bad block bitmap */

		goto err_out;

		return blk;



	/* check whether the inode table block number is set */

	bitmap_blk = ext4_inode_table(sb, desc);

	offset = bitmap_blk - group_first_block;

	blk = ext4_inode_table(sb, desc);

	offset = blk - group_first_block;

	next_zero_bit = ext4_find_next_zero_bit(bh->b_data,

				offset + EXT4_SB(sb)->s_itb_per_group,

				offset);

	if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)

		/* good bitmap for inode tables */

		return 1;



err_out:

	ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",

			block_group, bitmap_blk);

	if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)

		/* bad bitmap for inode tables */

		return blk;

	return 0;

}
@@ -336,13 +336,25 @@ void ext4_validate_block_bitmap(struct super_block *sb, 
			       unsigned int block_group,

			       struct buffer_head *bh)

{

	ext4_fsblk_t	blk;



	if (buffer_verified(bh))

		return;



	ext4_lock_group(sb, block_group);

	if (ext4_valid_block_bitmap(sb, desc, block_group, bh) &&

	    ext4_block_bitmap_csum_verify(sb, block_group, desc, bh,

					  EXT4_BLOCKS_PER_GROUP(sb) / 8))

	blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);

	if (unlikely(blk != 0)) {

		ext4_unlock_group(sb, block_group);

		ext4_error(sb, "bg %u: block %llu: invalid block bitmap",

			   block_group, blk);

		return;

	}

	if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,

			desc, bh, EXT4_BLOCKS_PER_GROUP(sb) / 8))) {

		ext4_unlock_group(sb, block_group);

		ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);

		return;

	}

	set_buffer_verified(bh);

	ext4_unlock_group(sb, block_group);

}

fs/ext4/bitmap.c

+0 −1
Original line number Diff line number Diff line
@@ -79,7 +79,6 @@ int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, 
	if (provided == calculated)

		return 1;



	ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);

	return 0;

}

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