We update information in logical volume integrity descriptor after each
allocation (as LVID contains free space, number of directories and files on
disk etc.). If the filesystem is on some phase change media, this leads to its
quick degradation as such media is able to handle only 10000 overwrites or so.
We solve the problem by writing new information into LVID only on umount,
remount-ro and sync. This solves the problem at the price of longer media
inconsistency (previously media became consistent after pdflush flushed dirty
LVID buffer) but that should be acceptable.

Report by and patch written in cooperation with
Rich Coe <Richard.Coe@med.ge.com>.

Signed-off-by: Jan Kara <jack@suse.cz>

Anchor block can be located at several places on the medium. Two of the
locations are relative to media end which is problematic to detect. Also
some drives report some block as last but are not able to read it or any
block nearby before it. So let's first try block 256 and if it is all fine,
don't look at other possible locations of anchor blocks to avoid IO errors.
This change required a larger reorganization of code but the new code is
hopefully more readable and definitely shorter.

Signed-off-by: Jan Kara <jack@suse.cz>

Make udf_check_valid() return 1 if the validity check passed and 0 otherwise.
So far it was the other way around which was a bit confusing. Also make
udf_vrs() return loff_t which is really the type it should return (not int).

Signed-off-by: Jan Kara <jack@suse.cz>

This patch makes the UDF FS driver use the hardware sector size as the
default logical block size, which is required by the UDF specifications.
While the previous default of 2048 bytes was correct for optical disks,
it was not for hard disks or USB storage devices, and made it impossible
to use such a device with the default mount options.  (The Linux mkudffs
tool uses a default block size of 2048 bytes even on devices with
smaller hardware sectors, so this bug is unlikely to be noticed unless
UDF-formatted USB storage devices are exchanged with other OSs.)

To avoid regressions for people who use loopback optical disk images or
who used the (sometimes wrong) defaults of mkudffs, we also try with
a block size of 2048 bytes if no anchor was found with the hardware
sector size.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jan Kara <jack@suse.cz>

The novrs mount option was broken due to a missing break.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jan Kara <jack@suse.cz>

Functions udf_CS0toNLS() and udf_NLStoCS0() didn't count with the fact that
NLS can return negative length when invalid character is given to it for
conversion. Thus interesting things could happen (such as overwriting random
memory with the rest of filename). Add appropriate checks.

Signed-off-by: Jan Kara <jack@suse.cz>

This patch makes udf return f_fsid info for statfs(2).

Signed-off-by: Coly Li <coly.li@suse.de>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>

Signed-off-by: Jan Kara <jack@suse.cz>

On x86 (and several other archs) mode_t is defined as "unsigned short"
and comparing unsigned shorts to negative ints is broken (because short
is promoted to int and then compared). Fix it.

Reported-and-tested-by: Laurent Riffard <laurent.riffard@free.fr>
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Fix sparse warnings:

  fs/udf/balloc.c:843:3: warning: returning void-valued expression
  fs/udf/balloc.c:847:3: warning: returning void-valued expression
  fs/udf/balloc.c:851:3: warning: returning void-valued expression
  fs/udf/balloc.c:855:3: warning: returning void-valued expression

Reported-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: Jan Kara <jack@suse.cz>