ubifs: make kobj_type structures constant

Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definitions to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

ubifs: Fix memory leak in ubifs_sysfs_init()

When insmod ubifs.ko, a kmemleak reported as below:

unreferenced object 0xffff88817fb1a780 (size 8):
comm "insmod", pid 25265, jiffies 4295239702 (age 100.130s)
hex dump (first 8 bytes):
75 62 69 66 73 00 ff ff ubifs...
backtrace:
[<ffffffff81b3fc4c>] slab_post_alloc_hook+0x9c/0x3c0
[<ffffffff81b44bf3>] __kmalloc_track_caller+0x183/0x410
[<ffffffff8198d3da>] kstrdup+0x3a/0x80
[<ffffffff8198d486>] kstrdup_const+0x66/0x80
[<ffffffff83989325>] kvasprintf_const+0x155/0x190
[<ffffffff83bf55bb>] kobject_set_name_vargs+0x5b/0x150
[<ffffffff83bf576b>] kobject_set_name+0xbb/0xf0
[<ffffffff8100204c>] do_one_initcall+0x14c/0x5a0
[<ffffffff8157e380>] do_init_module+0x1f0/0x660
[<ffffffff815857be>] load_module+0x6d7e/0x7590
[<ffffffff8158644f>] __do_sys_finit_module+0x19f/0x230
[<ffffffff815866b3>] __x64_sys_finit_module+0x73/0xb0
[<ffffffff88c98e85>] do_syscall_64+0x35/0x80
[<ffffffff88e00087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

When kset_register() failed, we should call kset_put to cleanup it.

Fixes: 2e3cbf425804 ("ubifs: Export filesystem error counters")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

ubifs: use default_groups in kobj_type

There are currently 2 ways to create a set of sysfs files for a
kobj_type, through the default_attrs field, and the default_groups
field. Move the ubifs sysfs code to use default_groups field which has
been the preferred way since aa30f47cf666 ("kobject: Add support for
default attribute groups to kobj_type") so that we can soon get rid of
the obsolete default_attrs field.

Cc: Stefan Schaeckeler <schaecsn@gmx.net>
Cc: linux-mtd@lists.infradead.org
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20220114104820.1340879-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ubifs: fix snprintf() length check

The snprintf() function returns the number of bytes (not including the
NUL terminator) which would have been printed if there were enough
space. So it can be greater than UBIFS_DFS_DIR_LEN. And actually if
it equals UBIFS_DFS_DIR_LEN then that's okay so this check is too
strict.

Fixes: 9a620291fc01 ("ubifs: Export filesystem error counters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

ubifs: Export filesystem error counters

Not all ubifs filesystem errors are propagated to userspace.

Export bad magic, bad node and crc errors via sysfs. This allows userspace
to notice filesystem errors:

/sys/fs/ubifs/ubiX_Y/errors_magic
/sys/fs/ubifs/ubiX_Y/errors_node
/sys/fs/ubifs/ubiX_Y/errors_crc

The counters are reset to 0 with a remount.

Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Signed-off-by: Richard Weinberger <richard@nod.at>