Commit d1cf5788 ("rbd: set mapping info earlier") defined
rbd_dev_mapping_clear(), but, just a few days after, commit
f35a4dee ("rbd: set the mapping size and features later") moved
rbd_dev_mapping_set() calls and added another rbd_dev_mapping_clear()
call instead of moving the old one.  Around the same time, another
duplicate was introduced in rbd_dev_device_release() - kill both.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

No point in providing an empty device_type::release callback and then
setting device::release for each rbd_dev dynamically.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

struct rbd_device has struct device embedded in it, which means it's
part of kobject universe and has an unpredictable life cycle.  Freeing
its memory outside of the release callback is flawed, yet commits
200a6a8b ("rbd: don't destroy rbd_dev in device release function")
and 8ad42cd0 ("rbd: don't have device release destroy rbd_dev")
moved rbd_dev_destroy() out to rbd_dev_image_release().

This commit reverts most of that, the key points are:

- rbd_dev->dev is initialized in rbd_dev_create(), making it possible
  to use rbd_dev_destroy() - which is just a put_device() - both before
  we register with device core and after.

- rbd_dev_release() (the release callback) is the only place we
  kfree(rbd_dev).  It's also where we do module_put(), keeping the
  module unload race window as small as possible.

- We pin the module in rbd_dev_create(), but only for mapping
  rbd_dev-s.  Moving image related stuff out of struct rbd_device into
  another struct which isn't tied with sysfs and device core is long
  overdue, but until that happens, this will keep rbd module refcount
  (which users can observe with lsmod) sane.

Fixes: http://tracker.ceph.com/issues/12697

Cc: Alex Elder <elder@linaro.org>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Returning pool id (i.e. >= 0) from a sysfs ->store() callback makes
userspace think it needs to retry the write.  Fix it - it's a leftover
from the times when the equivalent of rbd_dev_create() was the first
action in rbd_add().
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Remove unneeded NULL test.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@ expression x; @@
-if (x != NULL) {
  \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);
  x = NULL;
-}
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

rbd requires stable pages, as it performs a crc of the page data before
they are send to the OSDs.

But since kernel 3.9 (patch 1d1d1a76
"mm: only enforce stable page writes if the backing device requires
it") it is not assumed anymore that block devices require stable pages.

This patch sets the necessary flag to get stable pages back for rbd.

In a ceph installation that provides multiple ext4 formatted rbd
devices "bad crc" messages appeared regularly (ca 1 message every 1-2
minutes on every OSD that provided the data for the rbd) in the
OSD-logs before this patch. After this patch this messages are pretty
much gone (only ca 1-2 / month / OSD).

Cc: stable@vger.kernel.org # 3.9+, needs backporting
Signed-off-by: NRonny Hegewald <Ronny.Hegewald@online.de>
[idryomov@gmail.com: require stable pages only in crc case, changelog]
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

Mapping an image with a long parent chain (e.g. image foo, whose parent
is bar, whose parent is baz, etc) currently leads to a kernel stack
overflow, due to the following recursion in the reply path:

  rbd_osd_req_callback()
    rbd_obj_request_complete()
      rbd_img_obj_callback()
        rbd_img_parent_read_callback()
          rbd_obj_request_complete()
            ...

Limit the parent chain to 16 images, which is ~5K worth of stack.  When
the above recursion is eliminated, this limit can be lifted.

Fixes: http://tracker.ceph.com/issues/12538

Cc: stable@vger.kernel.org # 3.10+, needs backporting for < 4.2
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NJosh Durgin <jdurgin@redhat.com>

Currently we leak parent_spec and trigger a "parent reference
underflow" warning if rbd_dev_create() in rbd_dev_probe_parent() fails.
The problem is we take the !parent out_err branch and that only drops
refcounts; parent_spec that would've been freed had we called
rbd_dev_unparent() remains and triggers rbd_warn() in
rbd_dev_parent_put() - at that point we have parent_spec != NULL and
parent_ref == 0, so counter ends up being -1 after the decrement.

Redo rbd_dev_probe_parent() to fix this.

Cc: stable@vger.kernel.org # 3.10+, needs backporting for < 4.2
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

This covers only the simplest case - an object size sized write, but
it's still useful in tiering setups when EC is used for the base tier
as writefull op can be proxied, saving an object promotion.

Even though updating ceph_osdc_new_request() to allow writefull should
just be a matter of fixing an assert, I didn't do it because its only
user is cephfs.  All other sites were updated.

Reflects ceph.git commit 7bfb7f9025a8ee0d2305f49bf0336d2424da5b5b.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

Commit 30e2bc08 ("Revert "block: remove artifical max_hw_sectors
cap"") restored a clamp on max_sectors.  It's now 2560 sectors instead
of 1024, but it's not good enough: we set max_hw_sectors to rbd object
size because we don't want object sized I/Os to be split, and the
default object size is 4M.

So, set max_sectors to max_hw_sectors in rbd at queue init time.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

Resources are reallocated for requeued commands, so unmap and release
the iod for the failed command.

It's a pretty bad memory leak and causes a kernel hang if you remove a
drive because of a busy dma pool. You'll get messages spewing like this:

  nvme 0000:xx:xx.x: dma_pool_destroy prp list 256, ffff880420dec000 busy

and lock up pci and the driver since removal never completes while
holding a lock.

Cc: stable@vger.kernel.org
Cc: <stable@vger.kernel.org> # 4.0.x-
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Use a separate integer variable to hold the signed Linux errno
values we pass back to the block layer.  Note that for pass through
commands those might still be NVMe values, but those fit into the
int as well.

Fixes: f4829a9b: ("blk-mq: fix racy updates of rq->errors")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Compiling the nvme driver on 32-bit warns about a cast from a __u64
variable to a pointer:

drivers/block/nvme-core.c: In function 'nvme_submit_io':
drivers/block/nvme-core.c:1847:4: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
    (void __user *)io.addr, length, NULL, 0);

The cast here is intentional and safe, so we can shut up the
gcc warning by adding an intermediate cast to 'uintptr_t'.

I had previously submitted a patch to fix this problem in the
nvme driver, but it was accepted on the same day that two new
warnings got added.

For clarification, I also change the third instance of this cast
to use uintptr_t instead of unsigned long now.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: d29ec824 ("nvme: submit internal commands through the block layer")
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

The timeout handling introduced in
	7e2893a1 (nbd: Fix timeout detection)
introduces a race condition which may lead to killing of tasks that are
not in nbd context anymore. This was not observed or reproducable yet.

This patch adds locking to critical use of task_recv and task_send to
avoid killing tasks that already left the NBD thread functions. This
lock is only acquired if a timeout occures or the nbd device
starts/stops.
Reported-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NMarkus Pargmann <mpa@pengutronix.de>
Reviewed-by: NBen Hutchings <ben@decadent.org.uk>
Fixes: 7e2893a1 ("nbd: Fix timeout detection")
Signed-off-by: NJens Axboe <axboe@fb.com>

xen-blkfront will crash if the check to talk_to_blkback()
in blkback_changed()(XenbusStateInitWait) returns an error.
The driver data is freed and info is set to NULL. Later during
the close process via talk_to_blkback's call to xenbus_dev_fatal()
the null pointer is passed to and dereference in blkfront_closing.

CC: stable@vger.kernel.org
Signed-off-by: NCathy Avery <cathy.avery@oracle.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

blk_mq_complete_request may be a no-op if the request has already
been completed by others means (e.g. a timeout or cancellation), but
currently drivers have to set rq->errors before calling
blk_mq_complete_request, which might leave us with the wrong error value.

Add an error parameter to blk_mq_complete_request so that we can
defer setting rq->errors until we known we won the race to complete the
request.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The asynchronous namespace scanning caused affinity hints to be set before
its tagset initialized, so there was no cpu mask to set the hint. This
patch moves the affinity hint setting to after namespaces are scanned.
Reported-by: N김경산 <ks0204.kim@samsung.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This is due to  commit 86839c56
"xen/block: add multi-page ring support"

When using an guest under UEFI - after the domain is destroyed
the following warning comes from blkback.

------------[ cut here ]------------
WARNING: CPU: 2 PID: 95 at
/home/julien/works/linux/drivers/block/xen-blkback/xenbus.c:274
xen_blkif_deferred_free+0x1f4/0x1f8()
Modules linked in:
CPU: 2 PID: 95 Comm: kworker/2:1 Tainted: G        W       4.2.0 #85
Hardware name: APM X-Gene Mustang board (DT)
Workqueue: events xen_blkif_deferred_free
Call trace:
[<ffff8000000890a8>] dump_backtrace+0x0/0x124
[<ffff8000000891dc>] show_stack+0x10/0x1c
[<ffff8000007653bc>] dump_stack+0x78/0x98
[<ffff800000097e88>] warn_slowpath_common+0x9c/0xd4
[<ffff800000097f80>] warn_slowpath_null+0x14/0x20
[<ffff800000557a0c>] xen_blkif_deferred_free+0x1f0/0x1f8
[<ffff8000000ad020>] process_one_work+0x160/0x3b4
[<ffff8000000ad3b4>] worker_thread+0x140/0x494
[<ffff8000000b2e34>] kthread+0xd8/0xf0
---[ end trace 6f859b7883c88cdd ]---

Request allocation has been moved to connect_ring, which is called every
time blkback connects to the frontend (this can happen multiple times during
a blkback instance life cycle). On the other hand, request freeing has not
been moved, so it's only called when destroying the backend instance. Due to
this mismatch, blkback can allocate the request pool multiple times, without
freeing it.

In order to fix it, move the freeing of requests to xen_blkif_disconnect to
restore the symmetry between request allocation and freeing.
Reported-by: NJulien Grall <julien.grall@citrix.com>
Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
Tested-by: NJulien Grall <julien.grall@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: xen-devel@lists.xenproject.org
CC: stable@vger.kernel.org # 4.2
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

zcomp_create() verifies the success of zcomp_strm_{multi,single}_create()
through comp->stream, which can potentially be pointing to memory that
was freed if these functions returned an error.

While at it, replace a 'ERR_PTR(-ENOMEM)' by a more generic
'ERR_PTR(error)' as in the future zcomp_strm_{multi,siggle}_create()
could return other error codes.  Function documentation updated
accordingly.

Fixes: beca3ec7 ("zram: add multi stream functionality")
Signed-off-by: NLuis Henriques <luis.henriques@canonical.com>
Acked-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make zram syslog error reporting more consistent. We have random
error levels in some places. For example, critical errors like
  "Error allocating memory for compressed page"
and
  "Unable to allocate temp memory"
are reported as KERN_INFO messages.

a) Reassign error levels

Error messages that directly affect zram
functionality -- pr_err():

 Error allocating zram address table
 Error creating memory pool
 Decompression failed! err=%d, page=%u
 Unable to allocate temp memory
 Compression failed! err=%d
 Error allocating memory for compressed page: %u, size=%zu
 Cannot initialise %s compressing backend
 Error allocating disk queue for device %d
 Error allocating disk structure for device %d
 Error creating sysfs group for device %d
 Unable to register zram-control class
 Unable to get major number

Messages that do not affect functionality, but user
must be warned (because sysfs attrs will be removed in
this particular case) -- pr_warn():

 %d (%s) Attribute %s (and others) will be removed. %s

Messages that do not affect functionality and mostly are
informative -- pr_info():

 Cannot change max compression streams
 Can't change algorithm for initialized device
 Cannot change disksize for initialized device
 Added device: %s
 Removed device: %s

b) Update sysfs_create_group() error message

First, it lacks a trailing new line; add it.  Second, every error message
in zram_add() has a "for device %d" part, which makes errors more
informative.  Add missing part to "Error creating sysfs group" message.
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Compaction returns back to zram the number of migrated objects, which is
quite uninformative -- we have objects of different sizes so user space
cannot obtain any valuable data from that number.  Change compaction to
operate in terms of pages and return back to compaction issuer the
number of pages that were freed during compaction.  So from now on we
will export more meaningful value in zram<id>/mm_stat -- the number of
freed (compacted) pages.

This requires:
 (a) a rename of `num_migrated' to 'pages_compacted'
 (b) a internal API change -- return first_page's fullness_group from
     putback_zspage(), so we know when putback_zspage() did
     free_zspage().  It helps us to account compaction stats correctly.
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

`zs_compact_control' accounts the number of migrated objects but it has
a limited lifespan -- we lose it as soon as zs_compaction() returns back
to zram.  It worked fine, because (a) zram had it's own counter of
migrated objects and (b) only zram could trigger compaction.  However,
this does not work for automatic pool compaction (not issued by zram).
To account objects migrated during auto-compaction (issued by the
shrinker) we need to store this number in zs_pool.

Define a new `struct zs_pool_stats' structure to keep zs_pool's stats
there.  It provides only `num_migrated', as of this writing, but it
surely can be extended.

A new zsmalloc zs_pool_stats() symbol exports zs_pool's stats back to
caller.

Use zs_pool_stats() in zram and remove `num_migrated' from zram_stats.
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Suggested-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Need to free object_prefix when rbd_dev_v2_snap_context() fails, but
only if this is the first time we are reading in the header.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

If rbd_dev_image_probe() in rbd_dev_probe_parent() fails, header_name
is freed twice: once in rbd_dev_probe_parent() and then in its caller
rbd_dev_image_probe() (rbd_dev_image_probe() is called recursively to
handle parent images).

rbd_dev_probe_parent() is responsible for probing the parent, so it
shouldn't muck with clone's fields.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>

Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
is meant, I suspect this is because the first support for Xen was for
PV. This resulted in some misimplementation of helpers on ARM and
confused developers about the expected behavior.

For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
Although, if we look at the implementation on x86, it's returning a GFN.

For clarity and avoid new confusion, replace any reference to mfn with
gfn in any helpers used by PV drivers. The x86 code will still keep some
reference of pfn_to_mfn which may be used by all kind of guests
No changes as been made in the hypercall field, even
though they may be invalid, in order to keep the same as the defintion
in xen repo.

Note that page_to_mfn has been renamed to xen_page_to_gfn to avoid a
name to close to the KVM function gfn_to_page.

Take also the opportunity to simplify simple construction such
as pfn_to_mfn(page_to_pfn(page)) into xen_page_to_gfn. More complex clean up
will come in follow-up patches.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cbSigned-off-by: NJulien Grall <julien.grall@citrix.com>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

This will allow up to DISK_MAX_PARTS (256) partitions, with for example
GPT in the guest. Otherwise, the partition scan code will only discover
the first 15 partitions.
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

VIRTIO_BLK_F_CONFIG_WCE is important in order to achieve good performance
(up to 2x, though more realistically +30-40%) in latency-bound workloads.
However, it was removed by mistake together with VIRTIO_BLK_F_FLUSH.

It will be restored in the next revision of the virtio 1.0 standard, so
do the same in Linux.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

set_capacity() sets device's capacity using 512 bytes sectors.
null_blk calculates the number of sectors by size / bs, which
set_capacity is called with. This led to null_blk exposing the
wrong number of sectors when bs is not 512 bytes.
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Driver was not freeing the memory allocated for internal nullb queues.
This patch frees the memory during driver unload.
Signed-off-by: NMatias Bjørling <mb@lightnvm.io>
Signed-off-by: NJens Axboe <axboe@fb.com>

None of the implementations currently use it.  The common
bdev_direct_access() entry point handles all the size checks before
calling ->direct_access().
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

This patch enables the PRCHK and reftag support when PRACT bit is set, and
block layer integrity is disabled.
Signed-off-by: NAlok Pandey <pandey.alok@samsung.com>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Hi,

After commit f70ced09 (blk-mq: support per-distpatch_queue flush
machinery), the mtip32xx driver may oops upon module load due to walking
off the end of an array in mtip_init_cmd.  On initialization of the
flush_rq, init_request is called with request_index >= the maximum queue
depth the driver supports.  For mtip32xx, this value is used to index
into an array.  What this means is that the driver will walk off the end
of the array, and either oops or cause random memory corruption.

The problem is easily reproduced by doing modprobe/rmmod of the mtip32xx
driver in a loop.  I can typically reproduce the problem in about 30
seconds.

Now, in the case of mtip32xx, it actually doesn't support flush/fua, so
I think we can simply return without doing anything.  In addition, no
other mq-enabled driver does anything with the request_index passed into
init_request(), so no other driver is affected.  However, I'm not really
sure what is expected of drivers.  Ming, what did you envision drivers
would do when initializing the flush requests?
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Update the annotation for the kaddr pointer returned by direct_access()
so that it is a __pmem pointer.  This is consistent with the PMEM driver
and with how this direct_access() pointer is used in the DAX code.
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Note: This patch is based on original work of Arianna's internship for
GNOME's Outreach Program for Women.

Only one hardware queue is used now, so there is no significant
performance change

The legacy non-mq code is deleted completely which is the same as other
drivers like virtio, mtip, and nvme.

Also dropped one unnecessary holding of info->io_lock when calling
blk_mq_stop_hw_queues().
Signed-off-by: NArianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: NBob Liu <bob.liu@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NJens Axboe <axboe@fb.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Removing unreachable code from nvme_abort_req as nvme_submit_cmd has no
failure status to return.
Signed-off-by: NSunad Bhandary <sunad.s@samsung.com>
Acked-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The SG_GAPS queue flag caused checks for bio vector alignment against
PAGE_SIZE, but the device may have different constraints. This patch
adds a queue limits so a driver with such constraints can set to allow
requests that would have been unnecessarily split. The new gaps check
takes the request_queue as a parameter to simplify the logic around
invoking this function.

This new limit makes the queue flag redundant, so removing it and
all usage. Device-mappers will inherit the correct settings through
blk_stack_limits().
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

This reverts commit 34b48db6.
That commit caused performance regressions for streaming I/O
workloads on a number of different storage devices, from
SATA disks to external RAID arrays.  It also managed to
trip up some buggy firmware in at least one drive, causing
data corruption.

The next patch will bump the default max_sectors_kb value to
1280, which will accommodate a 10-data-disk stripe write
with chunk size 128k.  In the testing I've done using iozone,
fio, and aio-stress, a value of 1280 does not show a big
performance difference from 512.  This will hopefully still
help the software RAID setup that Christoph saw the original
performance gains with while still not regressing other
storage configurations.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Controllers can perform optional subsystem resets as introduced in NVMe
1.1. This patch adds an IOCTL to trigger the subsystem reset by writing
"NVMe" to the NSSR register.
Signed-off-by: NJon Derrick <jonathan.derrick@intel.com>
Acked-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Controllers part of an NVMe subsystem may be reset by any other controller
in the subsystem. If the device is capable of subsystem resets, this
patch adds detection for such events and performs appropriate controller
initialization upon subsystem reset detection.

The register bit is a RW1C type, so the driver needs to write a 1 to the
status bit to clear the subsystem reset occured bit during initialization.
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The logic in nvme_dev_add to enumerate namespaces was moved to
nvme_dev_scan. When moved, the nn variable is no longer used. This patch
removes it.

Fixes: a5768aa8i ("NVMe: Automatic namespace rescan")
Signed-off-by: NMatias Bjørling <m@bjorling.me>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>