Pull ext2, udf, and quota update from Jan Kara:
 "Some ext2 cleanups, a fix for UDF crash on corrupted media, and one
  quota locking fix"

* tag 'fs_for_4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  quota: Lock s_umount in exclusive mode for Q_XQUOTA{ON,OFF} quotactls.
  udf: Fix BUG on corrupted inode
  ext2: change reusable parameter to true when calling mb_cache_entry_create()
  ext2: remove redundant condition check
  ext2: avoid unnecessary operation in ext2_error()

When inode is corrupted so that extent type is invalid, some functions
(such as udf_truncate_extents()) will just BUG. Check that extent type
is valid when loading the inode to memory.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Commit c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
started to be more strict when checking whether converted strings are
properly formatted. Sudip reports that there are DVDs where the volume
identification string is actually too long - UDF reports:

[  632.309320] UDF-fs: incorrect dstring lengths (32/32)

during mount and fails the mount. This is mostly harmless failure as we
don't need volume identification (and even less volume set
identification) for anything. So just truncate the volume identification
string if it is too long and replace it with 'Invalid' if we just cannot
convert it for other reasons. This keeps slightly incorrect media still
mountable.

CC: stable@vger.kernel.org
Fixes: c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
Reported-and-tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Drop pack pragma. The header file defines only in-memory structures.

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

We don't support Free Space Table and Free Space Bitmap as specified by
UDF standard for writing as we don't support erasing blocks before
overwriting them. Just drop the handling of these structures as
partition descriptor checking code already makes sure such filesystems
can be mounted only read-only.

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

Fix a crash during an attempt to mount a filesystem that has both
Unallocated Space Table and Unallocated Space Bitmap. Such filesystem
actually violates the UDF standard so we just have to properly detect
such situation and refuse to mount such filesystem read-write. When we
are at it, verify also other constraints on the allocation information
mandated by the standard.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

There are certain filesystem features which we support for reading but
not for writing. We properly refuse to mount such filesystems read-write
however for some features (such as read-only partitions), we don't check
for these features when remounting the filesystem from read-only to
read-write. Thus such filesystems could be remounted read-write leading
to strange behavior (most likely crashes).

Fix the problem by marking in superblock whether the filesystem has some
features that are supported in read-only mode and check this flag during
remount.

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

Variables group_start and nr_groups are being assigned but are never used
hence they are redundant and can be removed.

Cleans up clang warning:
variable 'group_start' set but not used [-Wunused-but-set-variable]
variable 'nr_groups' set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Win7 is creating UDF filesystems with single partition with number 8192.
Current partition descriptor scanning code does not handle this well as
it incorrectly assumes that partition numbers will form mostly contiguous
space of small numbers. This results in unmountable media due to errors
like:

UDF-fs: error (device dm-1): udf_read_tagged: tag version 0x0000 != 0x0002 || 0x0003, block 0
UDF-fs: warning (device dm-1): udf_fill_super: No fileset found

Fix the problem by handling partition descriptors in a way that sparse
partition numbering does not matter.

Reported-and-tested-by: jean-luc malet <jeanluc.malet@gmail.com>
CC: stable@vger.kernel.org
Fixes: 7b78fd02fb19530fd101ae137a1f46aa466d9bb6
Signed-off-by: Jan Kara <jack@suse.cz>

Remove dead code and slightly simplify code in udf_find_fileset().

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