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

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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: Dave Jones <davej@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2012-08-10 13:57:52 -04:00
parent 7e731bc9a1
commit 7a4c5de27e
2 changed files with 37 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
fs/ext4/balloc.c
View File

@ -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,
struct ext4_group_desc *desc,
unsigned int block_group,
struct buffer_head *bh)
/*
* 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;
}
@ -336,14 +336,26 @@ 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))
set_buffer_verified(bh);
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);
}

1
fs/ext4/bitmap.c
View File

@ -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;
}