It is not very good to do IO in udf_clear_inode. First, VFS does not really
expect inode to become dirty there and thus we have to write it ourselves,
second, memory reclaim gets blocked waiting for IO when it does not really
expect it, third, the IO pattern (e.g. on umount) resulting from writes in
udf_clear_inode is bad and it slows down writing a lot.

The reason why UDF needed to do IO in udf_clear_inode is that UDF standard
mandates extent length to exactly match inode size. But when we allocate
extents to a file or directory, we don't really know what exactly the final
file size will be and thus temporarily set it to block boundary and later
truncate it to exact length in udf_clear_inode. Now, this is changed to
truncate to final file size in udf_release_file for regular files. For
directories and symlinks, we do the truncation at the moment when learn
what the final file size will be.

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

Some disks do not contain VAT inode in the last recorded block as required
by the standard but a few blocks earlier (or the number of recorded blocks
is wrong). So look for the VAT inode a bit before the end of the media.

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

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

When we close a file, we remove preallocated blocks from it. But this
truncation was not protected by i_mutex and thus it could have raced with a
write through a different fd and cause crashes or even filesystem corruption.

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

So far we preallocated blocks also for directories but that brings a
problem, when to get rid of preallocated blocks we don't need. So far
we removed them in udf_clear_inode() which has a disadvantage that
1) blocks are unavailable long after writing to a directory finished
   and thus one can get out of space unnecessarily early
2) releasing blocks from udf_clear_inode is problematic because VFS
   does not expect us to redirty inode there and it also slows down
   memory reclaim.

So preallocate blocks only for regular files where we can drop preallocation
in udf_release_file.

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

Recomputation of the pointer was wrong (it should have been just increment).
Luckily, we never use the computed value. Remove it.

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

Remove code that gets never used.

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

VAT inode is located in the last block recorded block of the medium. When the
drive errorneously reports number of recorded blocks, we failed to load the VAT
inode and thus mount the medium. This patch makes kernel try to read VAT inode
from the last block of the device if it is different from the last recorded
block.

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

first_block and goal are unsigned. When negative they are wrapped and caught by
the other test.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Some drives report 0 as the number of written blocks when there are some blocks
recorded. Use device size in such case so that we can automagically mount such
media.

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