UBI volume notifications are intended to create the API to get clients
notified about volume creation/deletion, renaming and re-sizing. A
client can subscribe to these notifications using 'ubi_volume_register()'
and cancel the subscription using 'ubi_volume_unregister()'. When UBI
volumes change, a blocking notifier is called. Clients also can request
"added" events on all volumes that existed before client subscribed
to the notifications.

If we use notifications instead of calling functions like 'ubi_gluebi_xxx()',
we can make the MTD emulation layer to be more flexible: build it as a
separate module and load/unload it on demand.

[Artem: many cleanups, rework locking, add "updated" event, provide
 device/volume info in notifiers]
Signed-off-by: NDmitry Pervushin <dpervushin@embeddedalley.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Various minor improvements to the debugging messages which
I found useful while hunting problems.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The mutex essencially protects the entire UBI device, so the
old @volumes_mutex name is a little misleading.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

The @mult_mutex does not serve any purpose. We already have
@volumes_mutex and it is enough. The @volume mutex is pushed
down to the 'ubi_rename_volumes()', because we want first
to open all volumes in the exclusive mode, and then lock the
mutex, just like all other ioctl's (remove, re-size, etc) do.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Now, we can call fsync() on an UBI volume.
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Introduce a new ioctl UBI_IOCSETPROP to set properties
on a volume. Also add the first property:
UBI_PROP_DIRECT_WRITE, this property is used to set the
ability to use direct writes in userspace
Signed-off-by: NSidney Amani <seed@uffs.org>
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Get rid of 'do_div()' and use more user-friendly primitives from
'linux/math64.h'.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI ioctl's do not work when running 64-bit kernel and 32-bit
user-land. Fix this by adding the compat_ioctl method.

Also, UBI serializes all ioctls, so more than one ioctl at a time
is not a problem. Amd UBI does not seem to depend on anything else,
so use unlocked_ioctl instead of ioctl (no BKL needed).
Reported-by: NGeert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>

Signed-off-by: NJan Engelhardt <jengelh@medozas.de>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Some ioctl's in UBI are enabled only when debugging is switched
on. There is not particular reason for this, just noone needed
them. However, some people need the now for their user-space
development. Thus, allow these ioctl's even if UBI debugging
is disabled.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

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

This patch adds ioctl to check if an LEB is mapped or not (as a
debugging option so far).

[Re-named ioctl to make it look the same as the other one and made
 some minor stylistic changes. Artem Bityutskiy.]
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch adds ioctl for the LEB unmap operation (as a debugging
option so far).

[Re-named ioctl to make it look the same as the other one and made
 some minor stylistic changes. Artem Bityutskiy.]
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch adds ioctl for the LEB map operation (as a debugging
option so far).

[Re-named ioctl to make it look the same as the other one and made
 some minor stylistic changes. Artem Bityutskiy.]
Signed-off-by: NCorentin Chary <corentincj@iksaif.net>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Just minor indentation and "over 80 characters" fixes.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

We do not need BKL in UBI because we serialize things
properly.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Just out or curiousity ran checkpatch.pl for whole UBI,
and discovered there are quite a few of stylistic issues.
Fix them.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Quite useful ioctl which allows to make atomic system upgrades.
The idea belongs to Richard Titmuss <richard_titmuss@logitech.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

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

Check that volume name is not shorter than 'name_len'.

No need to copy the trailing zero byte because whole array
was zeroed earlier.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NBruce Leonard <brucle@selinc.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI already checks that @min io size is the power of 2 at io_init.
It is save to use bit operations then.
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>

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

Instead of passing vol_id to all functions and then find
struct ubi_volume, pass struct ubi_volume pointer.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Since we do not change semantics of seek(), changing the file
pointer while updating does not make much sense.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/cdev.c: In function ‘vol_cdev_read’:
drivers/mtd/ubi/cdev.c:187: warning: unused variable ‘vol_id’
CC [M]  drivers/mtd/ubi/kapi.o
drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_erase’:
drivers/mtd/ubi/kapi.c:483: warning: unused variable ‘vol_id’
drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_unmap’:
drivers/mtd/ubi/kapi.c:544: warning: unused variable ‘vol_id’
drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_map’:
drivers/mtd/ubi/kapi.c:582: warning: unused variable ‘vol_id’
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Actually implement the MTD device attach/detach handlers.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This patch is a preparation to make UBI devices dynamic. It
adds an UBI control device which has dynamically allocated
major number and registers itself as "ubi_ctrl". It does not
do anything so far. The idea is that this device will allow
to attach/detach MTD devices from userspace.

This is symilar to what the Linux device mapper has.

The next things to do are:
* Fix UBI, because it now assumes UBI devices cannot go away
* Implement control device ioctls which will attach/detach MTD
  devices
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Make the code more consistent by requiring the caller to lock the
ubi->volume_mutex, because this is what we do for updates.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

When a volume is opened, get its kref via get_device() call.
And put the reference when closing the volume. With this, we
may have a bit saner volume delete.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Pass volume description object to the EBA function which makes
more sense, and EBA function do not have to find the volume
description object by volume ID.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

This global variablea is not really needed, remove it
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Always print error code with error messages, sometimes it is
extremely helpful info.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Remove redundant ubi->major field - we have it in ubi->cdev.dev
already.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

cdev.c whines in current git:

drivers/mtd/ubi/cdev.c: In function `major_to_device':
drivers/mtd/ubi/cdev.c:67: warning: control reaches end of non-void function

Shut it up.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

- don't do access_ok + get/put user but use the proper macro
- remove useless checks
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

Use coma at the the last elements of structure initializer.

Daniel Stone's explanation:

Because it turns:
-   .attr   = foo
+   .attr   = foo,
+   .bar    = baz

into:
+   .bar    = baz,

i.e., far less likely to screw up a merge.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>