udf: Don't corrupt unalloc spacetable when writing it
For a UDF filesystem configured with an Unallocated Space Table,
a filesystem operation that triggers an update to the table results
in on-disk corruption that prevents remounting:
udf_read_tagged: tag version 0x0000 != 0x0002 || 0x0003, block 274
For example:
1. Create a filesystem
$ mkudffs --media-type=hd --blocksize=512 --lvid=BUGTEST \
--vid=BUGTEST --fsid=BUGTEST --space=unalloctable \
/dev/mmcblk0
2. Mount it
# mount /dev/mmcblk0 /mnt
3. Create a file
$ echo "No corruption, please" > /mnt/new.file
4. Umount
# umount /mnt
5. Attempt remount
# mount /dev/mmcblk0 /mnt
This appears to be a longstanding bug caused by zero-initialization of
the Unallocated Space Entry block buffer and only partial repopulation
of required fields before writing to disk.
Commit 0adfb339fd64 ("udf: Fix unalloc space handling in udf_update_inode")
addressed one such field, but several others are required.
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Jan Kara <jack@suse.com>
1 file changed