With commit
f5e9c7d9aa1b: "ext4: don't update checksum of new
initialized bitmaps" the buffer valid bit will get set without
actually setting up the checksum for the allocation bitmap, since the
checksum will get calculated once we actually allocate an inode or
block.
If we are doing this, then we need to (re-)check the verified bit
after we take the block group lock. Otherwise, we could race with
another process reading and verifying the bitmap, which would then
complain about the checksum being invalid.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/
1780137
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
return -EFSCORRUPTED;
ext4_lock_group(sb, block_group);
+ if (buffer_verified(bh))
+ goto verified;
if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
desc, bh))) {
ext4_unlock_group(sb, block_group);
return -EFSCORRUPTED;
}
set_buffer_verified(bh);
+verified:
ext4_unlock_group(sb, block_group);
return 0;
}
return -EFSCORRUPTED;
ext4_lock_group(sb, block_group);
+ if (buffer_verified(bh))
+ goto verified;
blk = ext4_inode_bitmap(sb, desc);
if (!ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
EXT4_INODES_PER_GROUP(sb) / 8)) {
return -EFSBADCRC;
}
set_buffer_verified(bh);
+verified:
ext4_unlock_group(sb, block_group);
return 0;
}