bdev_get_queue() returns the request_queue associated with the
specified block_device.  blk_get_backing_dev_info() makes use of
bdev_get_queue() to determine the associated bdi given a block_device.

All the callers of bdev_get_queue() including
blk_get_backing_dev_info() assume that bdev_get_queue() may return
NULL and implement NULL handling; however, bdev_get_queue() requires
the passed in block_device is opened and attached to its gendisk.
Because an active gendisk always has a valid request_queue associated
with it, bdev_get_queue() can never return NULL and neither can
blk_get_backing_dev_info().

Make it clear that neither of the two functions can return NULL and
remove NULL handling from all the callers.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

BLKSECTGET ioctl loads the request queue's max_sectors as unsigned
short value to the argument pointer.  So if the max_sector is greater
than USHRT_MAX, the upper 16 bits of that is just discarded.

In such case, USHRT_MAX is more preferable than the lower 16 bits of
max_sectors.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.kernel.org
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

This patch fixes coccinelle error regarding usage of IS_ERR and
PTR_ERR instead of PTR_ERR_OR_ZERO.
Signed-off-by: NDuan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Introduce a BLKZEROOUT ioctl which can be used to clear block ranges by
way of blkdev_issue_zeroout().
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

65536 should be ludicrous anyway but without it we overflow the
memory computation doing the allocation and badness occurs.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Add a new operation code (BLKPG_RESIZE_PARTITION) to the BLKPG ioctl that
allows altering the size of an existing partition, even if it is currently
in use.

This patch converts hd_struct->nr_sects into sequence counter because
One might extend a partition while IO is happening to it and update of
nr_sects can be non-atomic on 32bit machines with 64bit sector_t. This
can lead to issues like reading inconsistent size of a partition. Sequence
counter have been used so that readers don't have to take bdev mutex lock
as we call sector_in_part() very frequently.

Now all the access to hd_struct->nr_sects should happen using sequence
counter read/update helper functions part_nr_sects_read/part_nr_sects_write.
There is one exception though, set_capacity()/get_capacity(). I think
theoritically race should exist there too but this patch does not
modify set_capacity()/get_capacity() due to sheer number of call sites
and I am afraid that change might break something. I have left that as a
TODO item. We can handle it later if need be. This patch does not introduce
any new races as such w.r.t set_capacity()/get_capacity().

v2: Add CONFIG_LBDAF test to UP preempt case as suggested by Phillip.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NPhillip Susi <psusi@ubuntu.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Introduce an ioctl which permits applications to query whether a block
device is rotational.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We're doing some odd things there, which already messes up various users
(see the net/socket.c code that this removes), and it was going to add
yet more crud to the block layer because of the incorrect error code
translation.

ENOIOCTLCMD is not an error return that should be returned to user mode
from the "ioctl()" system call, but it should *not* be translated as
EINVAL ("Invalid argument").  It should be translated as ENOTTY
("Inappropriate ioctl for device").

That EINVAL confusion has apparently so permeated some code that the
block layer actually checks for it, which is sad.  We continue to do so
for now, but add a big comment about how wrong that is, and we should
remove it entirely eventually.  In the meantime, this tries to keep the
changes localized to just the EINVAL -> ENOTTY fix, and removing code
that makes it harder to do the right thing.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move invalidate_bdev, block_sync_page into fs/block_dev.c.  Export
kill_bdev as well, so brd doesn't have to open code it.  Reduce
buffer_head.h requirement accordingly.

Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving.  The small comment replacing it says enough.
Signed-off-by: NNick Piggin <npiggin@suse.de>
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>

These files were getting <linux/module.h> via an implicit include
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

There are cases where suppressing partition scan is useful - e.g. for
lo devices and pseudo SATA devices which advertise to be a disk but
get upset on partition scan (some port multiplier control devices show
such behavior).

This patch adds GENHD_FL_NO_PART_SCAN which suppresses partition scan
regardless of the number of possible partitions.  disk_partitionable()
is renamed to disk_part_scan_enabled() as suppressing partition scan
doesn't imply the device can't be partitioned using
BLKPG_ADD/DEL_PARTITION calls from userland.  show_partition() now
directly tests disk_max_parts() to maintain backward-compatibility.

-v2: Updated to make it clear that only partition scan is suppressed
     not partitioning itself as suggested by Kay Sievers.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Adam Kovari and others reported that disconnecting an USB drive with
an ntfs-3g filesystem would cause "kernel BUG at fs/inode.c:1421!" to
be triggered.

The BUG could be traced back to ioctl(BLKBSZSET), which would
erroneously decrement the refcount on the bdev.  This is because
blkdev_get() expects the refcount to be already incremented and either
returns success or decrements the refcount and returns an error.

The bug was introduced by e525fd89 (block: make blkdev_get/put()
handle exclusive access), which didn't take into account this behavior
of blkdev_get().

This fixes
  https://bugzilla.kernel.org/show_bug.cgi?id=29202
(and likely 29792 too)
Reported-by: NAdam Kovari <kovariadam@gmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The big kernel lock has been removed from all these files at some point,
leaving only the #include.

Remove this too as a cleanup.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.

* blkdev_get/put() are the primary open and close functions.

* bd_claim/release() deal with exclusive open.

* open/close_bdev_exclusive() are combination of open and claim and
  the other way around, respectively.

* bd_link/unlink_disk_holder() to create and remove holder/slave
  symlinks.

* open_by_devnum() wraps bdget() + blkdev_get().

The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access.  Reorganize the interface such that,

* blkdev_get() is extended to include exclusive access management.
  @holder argument is added and, if is @FMODE_EXCL specified, it will
  gain exclusive access atomically w.r.t. other exclusive accesses.

* blkdev_put() is similarly extended.  It now takes @mode argument and
  if @FMODE_EXCL is set, it releases an exclusive access.  Also, when
  the last exclusive claim is released, the holder/slave symlinks are
  removed automatically.

* bd_claim/release() and close_bdev_exclusive() are no longer
  necessary and either made static or removed.

* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
  is no longer necessary and removed.

* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
  and blkdev_get().  It also has an unexpected extra bdev_read_only()
  test which probably should be moved into blkdev_get().

* open_by_devnum() is modified to take @holder argument and pass it to
  blkdev_get().

Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should).  This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.

open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features.  Well, let's leave them for another day.

Most conversions are straight-forward.  drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NNeil Brown <neilb@suse.de>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>

Structure hd_geometry is copied to userland with 4 padding bytes
between cylinders and start fields uninitialized on 64-bit platforms.
It leads to leaking of contents of kernel stack memory.

Currently there is no memset() in real implementations of getgeo()
in drivers/block/, so it makes sense to have memset() in blkdev_ioctl().
Signed-off-by: NVasiliy Kulikov <segooon@gmail.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Convert direct reads of an inode's i_size to using i_size_read().

i_size_{read,write} use a seqcount to protect reads from accessing
incomple writes.  Concurrent i_size_write()s require mutual exclussion
to protect the seqcount that is used by i_size_{read,write}.  But
i_size_read() callers do not need to use additional locking.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NNeilBrown <neilb@suse.de>
Acked-by: NLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

All the blkdev_issue_* helpers can only sanely be used for synchronous
caller.  To issue cache flushes or barriers asynchronously the caller needs
to set up a bio by itself with a completion callback to move the asynchronous
state machine ahead.  So drop the BLKDEV_IFL_WAIT flag that is always
specified when calling blkdev_issue_* and also remove the now unused flags
argument to blkdev_issue_flush and blkdev_issue_zeroout.  For
blkdev_issue_discard we need to keep it for the secure discard flag, which
gains a more descriptive name and loses the bitops vs flag confusion.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

I'm reposting this patch series as v4 since there have been no additional
comments, and I cleaned up one extra bit of unneeded code (in 3/3). The patches
are against Linus's tree: 2bfc96a1
(2.6.36-rc3).

Would this patchset be suitable for inclusion in an mm branch?

This changes adds a partition_meta_info struct which itself contains a
union of structures that provide partition table specific metadata.

This change leaves the union empty. The subsequent patch includes an
implementation for CONFIG_EFI_PARTITION-based metadata.
Signed-off-by: NWill Drewry <wad@chromium.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Secure discard is the same as discard except that all copies of the
discarded sectors (perhaps created by garbage collection) must also be
erased.
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Acked-by: NJens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The blkpg_ioctl and blkdev_reread_part access fields of
the bdev and gendisk structures, yet they always do so
under the protection of bdev->bd_mutex, which seems
sufficient.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
cked-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

We only call the functions set_device_ro(),
invalidate_bdev(), sync_filesystem() and sync_blockdev()
while holding the BKL in these commands. All
of these are also done in other code paths without
the BKL, which leads me to the conclusion that
the BKL is not needed here either.

The reason we hold it here is that it was originally
pushed down into the ioctl function from vfs_ioctl.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

The blktrace driver currently needs the BKL, but
we should not need to take that in the block layer,
so just push it down into the driver itself.

It is quite likely that the BKL is not actually
required in blktrace code and could be removed
in a follow-on patch.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

As a preparation for the removal of the big kernel
lock in the block layer, this removes the BKL
from the common ioctl handling code, moving it
into every single driver still using it.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

The patch just convert all blkdev_issue_xxx function to common
set of flags. Wait/allocation semantics preserved.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

The discard ioctl is used by mkfs utilities to clear a block device
prior to putting metadata down.  However, not all devices return zeroed
blocks after a discard.  Some drives return stale data, potentially
containing old superblocks.  It is therefore important to know whether
discarded blocks are properly zeroed.

Both ATA and SCSI drives have configuration bits that indicate whether
zeroes are returned after a discard operation.  Implement a block level
interface that allows this information to be bubbled up the stack and
queried via a new block device ioctl.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Not all users of the topology information want to use libblkid.  Provide
the topology information through bdev ioctls.

Also clarify sector size comments for existing BLK ioctls.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

blk_ioctl_discard duplicates large amounts of code from blkdev_issue_discard,
the only difference between the two is that blkdev_issue_discard needs to
send a barrier discard request and blk_ioctl_discard a non-barrier one,
and blk_ioctl_discard needs to wait on the request.  To facilitates this
add a flags argument to blkdev_issue_discard to control both aspects of the
behaviour.  This will be very useful later on for using the waiting
funcitonality for other callers.

Based on an earlier patch from Matthew Wilcox <matthew@wil.cx>.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Convert all external users of queue limits to using wrapper functions
instead of poking the request queue variables directly.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Until now we have had a 1:1 mapping between storage device physical
block size and the logical block sized used when addressing the device.
With SATA 4KB drives coming out that will no longer be the case.  The
sector size will be 4KB but the logical block size will remain
512-bytes.  Hence we need to distinguish between the physical block size
and the logical ditto.

This patch renames hardsect_size to logical_block_size.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Remove code handling bio_alloc failure with __GFP_WAIT.
GFP_KERNEL implies __GFP_WAIT.
Signed-off-by: NNikanth Karthikesan <knikanth@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

There's no need to take queue_lock or kernel_lock when modifying
bdi->ra_pages. So remove them. Also remove out of date comment for
queue_max_sectors_store().
Signed-off-by: NWu Fengguang <wfg@linux.intel.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Make add_partition() return pointer to the new hd_struct on success
and ERR_PTR() value on failure.  This change will be used to fix md
autodetection bug.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Now we can switch blkdev_ioctl() block_device/mode
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We need to do bd_claim() only if file hadn't been opened with O_EXCL
and then we have no need to use file itself as owner.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Most of that stuff doesn't need BKL at all; expand in the (only) caller,
merge the switch into one there and leave BKL only around the stuff that
might actually need it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

convert remaining callers to __blkdev_driver_ioctl()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

To keep the size of changesets sane we split the switch by drivers;
to keep the damn thing bisectable we do the following:
	1) rename the affected methods, add ones with correct
prototypes, make (few) callers handle both.  That's this changeset.
	2) for each driver convert to new methods.  *ALL* drivers
are converted in this series.
	3) kill the old (renamed) methods.

Note that it _is_ a flagday; all in-tree drivers are converted and by the
end of this series no trace of old methods remain.  The only reason why
we do that this way is to keep the damn thing bisectable and allow per-driver
debugging if anything goes wrong.

New methods:
	open(bdev, mode)
	release(disk, mode)
	ioctl(bdev, mode, cmd, arg)		/* Called without BKL */
	compat_ioctl(bdev, mode, cmd, arg)
	locked_ioctl(bdev, mode, cmd, arg)	/* Called with BKL, legacy */
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Analog of blkdev_driver_ioctl() with sane arguments.  For
now uses fake struct file, by the end of the series it won't
and blkdev_driver_ioctl() will become a wrapper around it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>