Some UDF media have special inodes (like VAT or metadata partition
inodes) whose link_count is 0. Thus commit 4071b9136223 (udf: Properly
detect stale inodes) broke loading these inodes because udf_iget()
started returning -ESTALE for them. Since we still need to properly
detect stale inodes queried by NFS, create two variants of udf_iget() -
one which is used for looking up special inodes (which ignores
link_count == 0) and one which is used for other cases which return
ESTALE when link_count == 0.

Fixes: 4071b913622316970d0e1919f7d82b4403fec5f2
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>

sys_tz is already declared in include/linux/time.h

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>

Currently write(2) updating i_size and close(2) of the file can race in
such a way that udf_truncate_tail_extent() called from
udf_file_release() sees old i_size but already new extents added by the
running write call. This results in complaints like:
  UDF-fs: warning (device vdb2): udf_truncate_tail_extent: Too long extent
    after EOF in inode 877: i_size: 0 lbcount: 1073739776 extent 0+1073739776
  UDF-fs: error (device vdb2): udf_truncate_tail_extent: Extent after EOF
    in inode 877

Fix the problem by grabbing i_mutex in udf_file_release() to be sure
i_size is consistent with current state of extent list. Also avoid
truncating tail extent unnecessarily when the file is still open for
writing.

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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>

Currently udf_iget() (triggered by NFS) can race with udf_new_inode()
leading to two inode structures with the same inode number:

nfsd: iget_locked() creates inode
nfsd: try to read from disk, block on that.
udf_new_inode(): allocate inode with that inumber
udf_new_inode(): insert it into icache, set it up and dirty
udf_write_inode(): write inode into buffer cache
nfsd: get CPU again, look into buffer cache, see nice and sane on-disk
  inode, set the in-core inode from it

Fix the problem by putting inode into icache in locked state (I_NEW set)
and unlocking it only after it's fully set up.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>

boilerplate code in udf_{create,mknod,symlink} taken to new helper

symlink case converted to unique id calculated by udf_new_inode() - no
point finding a new one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>

Currently UDF doesn't initialize i_generation in any way and thus NFS
can easily get reallocated inodes from stale file handles. Luckily UDF
already has a unique object identifier associated with each inode -
i_unique. Use that for initialization of i_generation.

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

NFS can easily ask for inodes that are already deleted. Currently UDF
happily returns such inodes which is a bug. Return -ESTALE if
udf_read_inode() is asked to read deleted inode.

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

Currently __udf_read_inode() wasn't returning anything and we found out
whether we succeeded reading inode by checking whether inode is bad or
not. udf_iget() returned NULL on failure and inode pointer otherwise.
Make these two functions properly propagate errors up the call stack and
use the return value in callers.

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

We did not implement any bound on number of indirect ICBs we follow when
loading inode. Thus corrupted medium could cause kernel to go into an
infinite loop, possibly causing a stack overflow.

Fix the possible stack overflow by removing recursion from
__udf_read_inode() and limit number of indirect ICBs we follow to avoid
infinite loops.

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