This patch makes it possible to mount UBI character device
nodes, and use something like:

$ mount -t ubifs /dev/ubi_volume_name /mnt/ubifs

instead of the old restrictive 'nodev' semantics:

$ mount -t ubifs ubi0_0 /mnt/ubifs

[Comments and the patch were amended a bit by Artem]
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

We do this automatically in get_sb_bdev() from the set_bdev_super()
callback. Filesystems that have their own private backing_dev_info
must assign that in ->fill_super().

Note that ->s_bdi assignment is required for proper writeback!
Acked-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This enables us to track who does what and print info. Its main use
is catching dirty inodes on the default_backing_dev_info, so we can
fix that up.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This adds two new exported functions:

- writeback_inodes_sb(), which only attempts to writeback dirty inodes on
  this super_block, for WB_SYNC_NONE writeout.
- sync_inodes_sb(), which writes out all dirty inodes on this super_block
  and also waits for the IO to complete.
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Add one more check to UBIFS - a check that makes sure that there
are no data nodes beyond inode size. And few commantaries fixes
along the line.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: NAdrian Hunter <Adrian.Hunter@nokia.com>

Nowadays VFS always synchronizes all dirty inodes and pages before
calling '->sync_fs()', so remove unneeded 'generic_sync_sb_inodes()'
from 'ubifs_sync_fs()'. It used to be needed, but not any longer.
Pointed-out-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The BKL was pushed down from VFS to the file-systems. It used
to serialize mount/unmount/remount and prevented more than one
instance of the same file-system from doing
mount/umount/remount at the same time. But it is OK for UBIFS
and it does not need any additional locking for these cases.
Thus, kick the BKL out of UBIFS.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBIFS uses a bdi device per volume, but does not care to hand out unique
names to each of them. This causes an error when trying to mount more
than one volumes. Append the UBI volume and device ID to avoid that.

[Amended a bit by Artem Bityutskiy]
Signed-off-by: NDaniel Mack <daniel@caiaq.de>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Cc: Adrian Hunter <ext-adrian.hunter@nokia.com>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When debugging is enabled and an unclean file-system is mounter,
the following assertion is triggered:

UBIFS assert failed in ubifs_tnc_start_commit at 805 (pid 1081)
Call Trace:
[cfaffbd0] [c0006cf8] show_stack+0x44/0x16c (unreliable)
[cfaffc10] [c011b738] ubifs_tnc_start_commit+0xbb8/0xd18
[cfaffc90] [c0112670] do_commit+0x150/0xa44
[cfaffd10] [c0125234] ubifs_rcvry_gc_commit+0xd8/0x544
[cfaffd60] [c0100e9c] ubifs_fill_super+0xe78/0x15f8
[cfaffdf0] [c0102118] ubifs_get_sb+0x20c/0x320
[cfaffe70] [c007f764] vfs_kern_mount+0x58/0xe0
[cfaffe90] [c007f83c] do_kern_mount+0x40/0xf8
[cfaffeb0] [c0095c24] do_mount+0x550/0x758
[cfafff10] [c0095ebc] sys_mount+0x90/0xe0
[cfafff40] [c000ed4c] ret_from_syscall+0x0/0x3c

The reason is that we initialize 'c->min_leb_idx' early, and do
not re-calculate it after journal replay.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch adds the following minor optimization:

1. If write-buffer does not use the timer, indicate it with the
   wbuf->no_timer variable, instead of using the wbuf->softlimit
   variable. This is better because wbuf->softlimit is of ktime_t
   type, and the ktime_to_ns function contains 64-bit multiplication.

2. Do not call the 'hrtimer_cancel()' function for write-buffers
   which do not use timers.

3. Do not cancel the timer in 'ubifs_put_super()' because the
   synchronization function does this.

This patch also removes a confusing comment.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

[xfs, btrfs, capifs, shmem don't need BKL, exempt]
Signed-off-by: NAlessio Igor Bogani <abogani@texware.it>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Move BKL into ->put_super from the only caller.  A couple of
filesystems had trivial enough ->put_super (only kfree and NULLing of
s_fs_info + stuff in there) to not get any locking: coda, cramfs, efs,
hugetlbfs, omfs, qnx4, shmem, all others got the full treatment.  Most
of them probably don't need it, but I'd rather sort that out individually.
Preferably after all the other BKL pushdowns in that area.

[AV: original used to move lock_super() down as well; these changes are
removed since we don't do lock_super() at all in generic_shutdown_super()
now]
[AV: fuse, btrfs and xfs are known to need no damn BKL, exempt]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Make sure a superblock really is writeable by checking MS_RDONLY
under s_umount.  sync_filesystems needed some re-arragement for
that, but all but one sync_filesystem caller had the correct locking
already so that we could add that check there.  cachefiles grew
s_umount locking.

I've also added a WARN_ON to sync_filesystem to assert this for
future callers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

UBIFS uses timers for write-buffer write-back. It is not
crucial for us to write-back exactly on time. We are fine
to write-back a little earlier or later. And this means
we may optimize UBIFS timer so that it could be groped
with a close timer event, so that the CPU would not be
waken up just to do the write back. This is optimization
to lessen power consumption, which is important in
embedded devices UBIFS is used for.

hrtimers have a nice feature: they are effectively range
timers, and we may defind the soft and hard limits for
it. Standard timers do not have these feature. They may
only be made deferrable, but this means there is effectively
no hard limit. So, we will better use hrtimers.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Reviewed-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When passing UBIFS parameters via kernel command line, the
sync option will be passed to UBIFS as a string, not as an
MS_SYNCHRONOUS flag. Teach UBIFS interpreting this flag.
Reported-by: NAurélien GÉRÔME <ag@debian.org>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBIFS has erroneuosly set 'sb->s_dev' to the UBI volume
character device major/minor. This may lead to clashes
if there is another FS mounted to a block device with
the same major/minor numbers. User-space programs which
use 'stat->st_dev' may get confused because of this.

This problem was found by Al Viro. He also pointed the
way to fix the problem - use 'set_anon_super()' and
'kill_anon_super()' VFS helpers.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

If the compressor is not present, mount_ubifs need
to return an error code. This way ubifs_fill_super
will stop and handle the error.
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

When UBIFS runs out of space it spends a lot of time trying to
find more space before returning ENOSPC.  As there is no point
repeating that unless something has changed, UBIFS has an
optimization to record that the file system is 100% full and not
try to find space.  That flag was not being reset when a pending
deletion was finally done.
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Reviewed-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

simple_set_mnt() is defined as returning 'int' but always returns 0.
Callers assume simple_set_mnt() never fails and don't properly cleanup if
it were to _ever_ fail.  For instance, get_sb_single() and get_sb_nodev()
should:

        up_write(sb->s_unmount);
        deactivate_super(sb);

if simple_set_mnt() fails.

Since simple_set_mnt() never fails, would be cleaner if it did not
return anything.

[akpm@linux-foundation.org: fix build]
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Now UBIFS is supported by u-boot. If we ever decide to change the
media format, then people will have to upgrade their u-boots to
mount new format images. However, very often it is possible to
preserve R/O forward-compatibility, even though the write
forward-compatibility is not preserved.

This patch introduces a new super-block field which stores the
R/O compatibility version.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: NAdrian Hunter <Adrian.Hunter@nokia.com>

fs/ubifs/super.c: In function ‘ubifs_show_options’:
fs/ubifs/super.c:425: warning: format not a string literal and no format arguments
fs/ubifs/super.c: In function ‘mount_ubifs’:
fs/ubifs/super.c:1204: warning: format not a string literal and no format arguments
fs/ubifs/super.c: In function ‘ubifs_remount_rw’:
fs/ubifs/super.c:1557: warning: format not a string literal and no format arguments
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch introduces a helpful @c->idx_leb_size variable.
The patch also fixes some spelling issues and makes comments
use "LEB" instead of "eraseblock", which is more correct.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Empty journal head LEBs are accounted as taken empty as well, so
the GC LEB does not have to be the only taken empty LEB when
nounting/remounting.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This UBIFS feature has never worked properly, and it was a mistake
to add it because we simply have no use-cases. So, lets still accept
the fast_unmount mount option, but ignore it. This does not change
much, because UBIFS commit in sync_fs anyway, and sync_fs is called
while unmounting.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When mounting/re-mounting, UBIFS returns EINVAL even if the ENOSPC
or EROFS codes are are much better, just because we have not found
references to ENOSPC/EROFS in mount (2) man pages. This patch
changes this behaviour and makes UBIFS return real error code,
because:

1. It is just less confusing and more logical
2. mount is not described in SuSv3, so it seems to be not really
   well-standartized
3. we do not cover all cases, and any random undocumented in man
   pages error code may be returned anyway
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

- preserve the idx_gc list - it will be needed in the same
state, should UBIFS be remounted rw again
- prevent remounting ro if we have switched to read only
mode (due to a fatal error)
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

All writes go through wbufs so they must be sync'd
after syncing inodes and pages.
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

I introduce wrong assertions in one of the previous commits, this
patch fixes them.

Also, initialize debugfs after the debugging check. This is a little
nicer because we want the FS data to be accessible to external users
after everything has been initialized.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When mounting read-only the orphan area head is
not initialized.  It must be initialized when
remounting read/write, but it was not.  This patch
fixes that.

[Artem: sorry, added comment tweaking noise]
Signed-off-by: NAdrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When we mount UBIFS, GC LEB may contain out-of-date information,
and UBIFS should update lprops and set free space for thei LEB.
Currently UBIFS does this only if mounted R/W. But for R/O mount
we have to do the same, because otherwise we will have incorrect
FS free space reported to user-space.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

We observe space corrupted accounting when re-mounting. So add some
debbugging checks to catch problems like this.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When freeing the c->idx_lebs list, we have to release the LEBs as well,
because we might be called from mount to read-only mode code. Otherwise
the LEBs stay taken forever, which may cause problems when we re-mount
back ro RW mode.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Just add more commentaries. Also some commentary fixes for
lprops flags.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Mark super, file, and inode operation structcutes with 'const'.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

VFS calls '->sync_fs()' twice - first time with @wait = 0, second
time with @wait = 1. As a result, we may commit and synchronize
write-buffers twice. Avoid doing this by returning immediatelly if
@wait = 0.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

WB_SYNC_HOLD is going to be zapped so we should not use it. Use
%WB_SYNC_NONE instead. Here is what akpm said:

"I think I'll just switch that to WB_SYNC_NONE.  The `wait==0' mode is
just an advisory thing to help the fs shove lots of data into the
queues.  If some gets missed then it'll be picked up on the second
->sync_fs call, with wait==1."

Thanks to Randy Dunlap for catching this.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>