ANA log parsing invokes nvme_update_ana_state() per ANA group desc.
This updates the state of namespaces with nsids in desc->nsids[].

Both ctrl->namespaces list and desc->nsids[] array are sorted by nsid.
Hence nvme_update_ana_state() performs a single walk over ctrl->namespaces:
- if current namespace matches the current desc->nsids[n],
  this namespace is updated, and n is incremented.
- the process stops when it encounters the end of either
  ctrl->namespaces end or desc->nsids[]

In case desc->nsids[n] does not match any of ctrl->namespaces,
the remaining nsids following desc->nsids[n] will not be updated.
Such situation was considered abnormal and generated WARN_ON_ONCE.

However ANA log MAY contain nsids not (yet) found in ctrl->namespaces.
For example, lets consider the following scenario:
- nvme0 exposes namespaces with nsids = [2, 3] to the host
- a new namespace nsid = 1 is added dynamically
- also, a ANA topology change is triggered
- NS_CHANGED aen is generated and triggers scan_work
- before scan_work discovers nsid=1 and creates a namespace, a NOTICE_ANA
  aen was issues and ana_work receives ANA log with nsids=[1, 2, 3]

Result: ana_work fails to update ANA state on existing namespaces [2, 3]

Solution:
Change the way nvme_update_ana_state() namespace list walk
checks the current namespace against desc->nsids[n] as follows:
a) ns->head->ns_id < desc->nsids[n]: keep walking ctrl->namespaces.
b) ns->head->ns_id == desc->nsids[n]: match, update the namespace
c) ns->head->ns_id >= desc->nsids[n]: skip to desc->nsids[n+1]

This enables correct operation in the scenario described above.
This also allows ANA log to contain nsids currently invisible
to the host, i.e. inactive nsids.
Signed-off-by: NAnton Eidelman <anton@lightbitslabs.com>
Reviewed-by: NJames Smart <james.smart@broadcom.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>

Fix a crash with multipath activated. It happends when ANA log
page is larger than MDTS and because of that ANA is disabled.
The driver then tries to access unallocated buffer when connecting
to a nvme target. The signature is as follows:

[  300.433586] nvme nvme0: ANA log page size (8208) larger than MDTS (8192).
[  300.435387] nvme nvme0: disabling ANA support.
[  300.437835] nvme nvme0: creating 4 I/O queues.
[  300.459132] nvme nvme0: new ctrl: NQN "nqn.0.0.0", addr 10.91.0.1:8009
[  300.464609] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[  300.466342] #PF error: [normal kernel read fault]
[  300.467385] PGD 0 P4D 0
[  300.467987] Oops: 0000 [#1] SMP PTI
[  300.468787] CPU: 3 PID: 50 Comm: kworker/u8:1 Not tainted 5.0.20kalray+ #4
[  300.470264] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[  300.471532] Workqueue: nvme-wq nvme_scan_work [nvme_core]
[  300.472724] RIP: 0010:nvme_parse_ana_log+0x21/0x140 [nvme_core]
[  300.474038] Code: 45 01 d2 d8 48 98 c3 66 90 0f 1f 44 00 00 41 57 41 56 41 55 41 54 55 53 48 89 fb 48 83 ec 08 48 8b af 20 0a 00 00 48 89 34 24 <66> 83 7d 08 00 0f 84 c6 00 00 00 44 8b 7d 14 49 89 d5 8b 55 10 48
[  300.477374] RSP: 0018:ffffa50e80fd7cb8 EFLAGS: 00010296
[  300.478334] RAX: 0000000000000001 RBX: ffff9130f1872258 RCX: 0000000000000000
[  300.479784] RDX: ffffffffc06c4c30 RSI: ffff9130edad4280 RDI: ffff9130f1872258
[  300.481488] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
[  300.483203] R10: 0000000000000220 R11: 0000000000000040 R12: ffff9130f18722c0
[  300.484928] R13: ffff9130f18722d0 R14: ffff9130edad4280 R15: ffff9130f18722c0
[  300.486626] FS:  0000000000000000(0000) GS:ffff9130f7b80000(0000) knlGS:0000000000000000
[  300.488538] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  300.489907] CR2: 0000000000000008 CR3: 00000002365e6000 CR4: 00000000000006e0
[  300.491612] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  300.493303] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  300.494991] Call Trace:
[  300.495645]  nvme_mpath_add_disk+0x5c/0xb0 [nvme_core]
[  300.496880]  nvme_validate_ns+0x2ef/0x550 [nvme_core]
[  300.498105]  ? nvme_identify_ctrl.isra.45+0x6a/0xb0 [nvme_core]
[  300.499539]  nvme_scan_work+0x2b4/0x370 [nvme_core]
[  300.500717]  ? __switch_to_asm+0x35/0x70
[  300.501663]  process_one_work+0x171/0x380
[  300.502340]  worker_thread+0x49/0x3f0
[  300.503079]  kthread+0xf8/0x130
[  300.503795]  ? max_active_store+0x80/0x80
[  300.504690]  ? kthread_bind+0x10/0x10
[  300.505502]  ret_from_fork+0x35/0x40
[  300.506280] Modules linked in: nvme_tcp nvme_rdma rdma_cm iw_cm ib_cm ib_core nvme_fabrics nvme_core xt_physdev ip6table_raw ip6table_mangle ip6table_filter ip6_tables xt_comment iptable_nat nf_nat_ipv4 nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xt_CHECKSUM iptable_mangle iptable_filter veth ebtable_filter ebtable_nat ebtables iptable_raw vxlan ip6_udp_tunnel udp_tunnel sunrpc joydev pcspkr virtio_balloon br_netfilter bridge stp llc ip_tables xfs libcrc32c ata_generic pata_acpi virtio_net virtio_console net_failover virtio_blk failover ata_piix serio_raw libata virtio_pci virtio_ring virtio
[  300.514984] CR2: 0000000000000008
[  300.515569] ---[ end trace faa2eefad7e7f218 ]---
[  300.516354] RIP: 0010:nvme_parse_ana_log+0x21/0x140 [nvme_core]
[  300.517330] Code: 45 01 d2 d8 48 98 c3 66 90 0f 1f 44 00 00 41 57 41 56 41 55 41 54 55 53 48 89 fb 48 83 ec 08 48 8b af 20 0a 00 00 48 89 34 24 <66> 83 7d 08 00 0f 84 c6 00 00 00 44 8b 7d 14 49 89 d5 8b 55 10 48
[  300.520353] RSP: 0018:ffffa50e80fd7cb8 EFLAGS: 00010296
[  300.521229] RAX: 0000000000000001 RBX: ffff9130f1872258 RCX: 0000000000000000
[  300.522399] RDX: ffffffffc06c4c30 RSI: ffff9130edad4280 RDI: ffff9130f1872258
[  300.523560] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
[  300.524734] R10: 0000000000000220 R11: 0000000000000040 R12: ffff9130f18722c0
[  300.525915] R13: ffff9130f18722d0 R14: ffff9130edad4280 R15: ffff9130f18722c0
[  300.527084] FS:  0000000000000000(0000) GS:ffff9130f7b80000(0000) knlGS:0000000000000000
[  300.528396] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  300.529440] CR2: 0000000000000008 CR3: 00000002365e6000 CR4: 00000000000006e0
[  300.530739] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  300.531989] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  300.533264] Kernel panic - not syncing: Fatal exception
[  300.534338] Kernel Offset: 0x17c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[  300.536227] ---[ end Kernel panic - not syncing: Fatal exception ]---

Condition check refactoring from Christoph Hellwig.
Signed-off-by: NMarta Rybczynska <marta.rybczynska@kalray.eu>
Tested-by: NJean-Baptiste Riaux <jbriaux@kalray.eu>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

nvme_ns_remove() will first set the NVME_NS_REMOVING flag before removing
it from the list at the very last step.
So to avoid selecting a namespace in nvme_find_path() which is about to be
removed check the NVME_NS_REMOVING flag, too, when selecting a new path.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When we have a singular list in nvme_round_robin_path() we still
need to check its validity.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Factor our a common helper to check if a path has been disabled
by something other than the per-namespace ANA state.
Signed-off-by: NHannes Reinecke <hare@suse.com>
[hch: split from a bigger patch]
Signed-off-by: NChristoph Hellwig <hch@lst.de>

A process holding an open reference to a removed disk prevents it
from completing deletion, so its name continues to exist. A subsequent
gendisk creation may have the same cntlid which risks collision when
using that for the name. Use the unique ctrl->instance instead.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

If the bio is moved to a different queue via blk_steal_bios() and
the original queue is destroyed in nvme_remove_ns() we'll be ending
with a crash in bio_endio() as the mempool for the split bio bvecs
had already been destroyed.
So split the bio using the original queue (which will remain during the
lifetime of the bio) before sending it down to the underlying device.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When undergoing state transitions I/O might be requeued, hence
we should always call nvme_mpath_set_live() to schedule requeue_work
whenever the nvme device is live, independent on whether the
old state was live or not.
Signed-off-by: NMartin George <marting@netapp.com>
Signed-off-by: NGargi Srinivas <sring@netapp.com>
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Update license to use SPDX-License-Identifier instead of verbose license
text.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>

Implement a simple round-robin I/O policy for multipathing.  Path
selection is done in two rounds, first iterating across all optimized
paths, and if that doesn't return any valid paths, iterate over all
optimized and non-optimized paths.  If no paths are found, use the
existing algorithm.  Also add a sysfs attribute 'iopolicy' to switch
between the current NUMA-aware I/O policy and the 'round-robin' I/O
policy.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Bit 6 in the ANACAP field is used to indicate that the ANA group ID
doesn't change while the namespace is attached to the controller.
There is an optimisation in the code to only allocate space
for the ANA group header, as the namespace list won't change and
hence would not need to be refreshed.
However, this optimisation was never carried over to the actual
workflow, which always assumes that the buffer is large enough
to hold the ANA header _and_ the namespace list.
So drop this optimisation and always allocate enough space.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

When nvme_init_identify() fails the ANA log buffer is deallocated
but _not_ set to NULL. This can cause double free oops when this
controller is deleted without ever being reconnected.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Instead of directly poking into the struct device add a new numa_node
field to struct nvme_ctrl.  This allows fabrics drivers where ctrl->dev
is a virtual device to support NUMA affinity as well.

Also expose the field as a sysfs attribute, and populate it for the
RDMA and FC transports.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The ->poll_fn has been stale for a while, as a lot of places check for mq
ops.  But there is no real point in it anyway, as we don't even use
the multipath code for subsystems without multiple ports, which is usually
what we do high performance I/O to.  If it really becomes an issue we
should rework the nvme code to also skip the multipath code for any
private namespace, even if that could mean some trouble when rescanning.
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_poll() has always kept spinning until it found an IO. This is
fine for SYNC polling, since we need to find one request we have
pending, but in preparation for ASYNC polling it can be beneficial
to just check if we have any entries available or not.

Existing callers are converted to pass in 'spin == true', to retain
the old behavior.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We currently only really support sync poll, ie poll with 1 IO in flight.
This prepares us for supporting async poll.

Note that the returned value isn't necessarily 100% accurate. If poll
races with IRQ completion, we assume that the fact that the task is now
runnable means we found at least one entry. In reality it could be more
than 1, or not even 1. This is fine, the caller will just need to take
this into account.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

With the legacy request path gone there is no real need to override the
queue_lock.
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Whenever we update ns_head info, we need to make sure it is still
compatible with all underlying backing devices because although nvme
multipath doesn't have any explicit use of these limits, other devices
can still be stacked on top of it which may rely on the underlying limits.
Start with unlimited stacking limits, and every info update iterate over
siblings and adjust queue limits.
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The nvme namespace paths were being updated only when the current path
was not set or nonoptimized. If a new path comes online that is a better
path for its NUMA node, the multipath selector may continue using the
previously set path on a potentially further node.

This patch re-runs the path assignment after successfully adding a new
optimized path.
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Make current_path an array with an entry for every possible node, and
cache the best path on a per-node basis.  Take the node distance into
account when selecting it.  This is primarily useful for dual-ported PCIe
devices which are connected to PCIe root ports on different sockets.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>

When an io is rejected by nvmf_check_ready() due to validation of the
controller state, the nvmf_fail_nonready_command() will normally return
BLK_STS_RESOURCE to requeue and retry.  However, if the controller is
dying or the I/O is marked for NVMe multipath, the I/O is failed so that
the controller can terminate or so that the io can be issued on a
different path.  Unfortunately, as this reject point is before the
transport has accepted the command, blk-mq ends up completing the I/O
and never calls nvme_complete_rq(), which is where multipath may preserve
or re-route the I/O. The end result is, the device user ends up seeing an
EIO error.

Example: single path connectivity, controller is under load, and a reset
is induced.  An I/O is received:

  a) while the reset state has been set but the queues have yet to be
     stopped; or
  b) after queues are started (at end of reset) but before the reconnect
     has completed.

The I/O finishes with an EIO status.

This patch makes the following changes:

  - Adds the HOST_PATH_ERROR pathing status from TP4028
  - Modifies the reject point such that it appears to queue successfully,
    but actually completes the io with the new pathing status and calls
    nvme_complete_rq().
  - nvme_complete_rq() recognizes the new status, avoids resetting the
    controller (likely was already done in order to get this new status),
    and calls the multipather to clear the current path that errored.
    This allows the next command (retry or new command) to select a new
    path if there is one.
Signed-off-by: NJames Smart <jsmart2021@gmail.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

We should be registering the ns_id attribute as default sysfs
attribute groups, otherwise we have a race condition between
the uevent and the attributes appearing in sysfs.
Suggested-by: NBart van Assche <bvanassche@acm.org>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Update device_add_disk() to take an 'groups' argument so that
individual drivers can register a device with additional sysfs
attributes.
This avoids race condition the driver would otherwise have if these
groups were to be created with sysfs_add_groups().
Signed-off-by: NMartin Wilck <martin.wilck@suse.com>
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NSusobhan Dey <susobhan.dey@gmail.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When the initial discovery fails the subsystem hasn't been setup yet
in nvme_mpath_stop, and we can't dereference ctrl->subsys.

Fixes: 0d0b660f ("nvme: add ANA support")
Signed-off-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Add support for Asynchronous Namespace Access as specified in NVMe 1.3
TP 4004.  With ANA each namespace attached to a controller belongs to an
ANA group that describes the characteristics of accessing the namespaces
through this controller.  In the optimized and non-optimized states
namespaces can be accessed regularly, although in a multi-pathing
environment we should always prefer to access a namespace through a
controller where an optimized relationship exists.  Namespaces in
Inaccessible, Permanent-Loss or Change state for a given controller
should not be accessed.

The states are updated through reading the ANA log page, which is read
once during controller initialization, whenever the ANA change notice
AEN is received, or when one of the ANA specific status codes that
signal a state change is received on a command.

The ANA state is kept in the nvme_ns structure, which makes the checks in
the fast path very simple.  Updating the ANA state when reading the log
page is also very simple, the only downside is that finding the initial
ANA state when scanning for namespaces is a bit cumbersome.

The gendisk for a ns_head is only registered once a live path for it
exists.  Without that the kernel would hang during partition scanning.

Includes fixes and improvements from Hannes Reinecke.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>

Now that we just call out to blk_path_error there isn't really any good
reason to not merge it into the only caller.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>

Adding a tracepoint to trace bio remapping for native nvme multipath.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When CONFIG_NVME_MULTIPATH is set, but we're not using nvme to multipath,
namespaces with multiple paths were not creating unique names due to
reusing the same instance number from the namespace's head.

This patch fixes this by falling back to the non-multipath naming method
when the parameter disabled using multipath.
Reported-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We can't allow the user to change multipath settings at runtime, as this
will create naming conflicts due to the different naming schemes used
for each mode.
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

namespaces_mutext is used to synchronize the operations on ctrl
namespaces list. Most of the time, it is a read operation.

On the other hand, there are many interfaces in nvme core that
need this lock, such as nvme_wait_freeze, and even more interfaces
will be added. If we use mutex here, circular dependency could be
introduced easily. For example:
context A                  context B
nvme_xxx                   nvme_xxx
hold namespaces_mutext     require namespaces_mutext
sync context B

So it is better to change it from mutex to rwsem.
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch has been generated as follows:

for verb in set_unlocked clear_unlocked set clear; do
  replace-in-files queue_flag_${verb} blk_queue_flag_${verb%_unlocked} \
    $(git grep -lw queue_flag_${verb} drivers block/bsg*)
done

Except for protecting all queue flag changes with the queue lock
this patch does not change any functionality.

Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This reverts commit e9a48034.

The slaves and holders link for the hidden gendisks confuse lsblk so that
it errors out on, or doesn't report the nvme multipath devices.  Given
that we don't need holder relationships for something that can't even be
directly accessed we should just stop creating those links.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reported-by: NPotnuri Bharat Teja <bharat@chelsio.com>
Cc: stable@vger.kernel.org
Signed-off-by: NKeith Busch <keith.busch@intel.com>

This patch does not change any functionality.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If multipathing is enabled, each NVMe subsystem creates a head
namespace (e.g., nvme0n1) and multiple private namespaces
(e.g., nvme0c0n1 and nvme0c1n1) in sysfs. When creating links for
private namespaces, links of head namespace are used, so the
namespace creation order must be followed (e.g., nvme0n1 ->
nvme0c1n1). If the order is not followed, links of sysfs will be
incomplete or kernel panic will occur.

The kernel panic was:
  kernel BUG at fs/sysfs/symlink.c:27!
  Call Trace:
    nvme_mpath_add_disk_links+0x5d/0x80 [nvme_core]
    nvme_validate_ns+0x5c2/0x850 [nvme_core]
    nvme_scan_work+0x1af/0x2d0 [nvme_core]

Correct order
Context A     Context B
nvme0n1
nvme0c0n1     nvme0c1n1

Incorrect order
Context A     Context B
              nvme0c1n1
nvme0n1
nvme0c0n1

The nvme_mpath_add_disk (for creating head namespace) is called
just before the nvme_mpath_add_disk_links (for creating private
namespaces). In nvme_mpath_add_disk, the first context acquires
the lock of subsystem and creates a head namespace, and other
contexts do nothing by checking GENHD_FL_UP of a head namespace
after waiting to acquire the lock. We verified the code with or
without multipathing using three vendors of dual-port NVMe SSDs.
Signed-off-by: NBaegjae Sung <baegjae@gmail.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NKeith Busch <keith.busch@intel.com>

Uses common code for determining if an error should be retried on
alternate path.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This removes nvme multipath's specific status decoding to see if failover
is needed, using the generic blk_status_t that was decoded earlier. This
abstraction from the raw NVMe status means all status decoding exists
in one place.
Acked-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Trivial fix to spelling mistake in dev_warn_ratelimited message text
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When creating nvme multipath devices we should populate the 'slaves' and
'holders' directorys properly to aid userspace topology detection.
Signed-off-by: NHannes Reinecke <hare@suse.com>
[hch: split from a larger patch, compile fix for CONFIG_NVME_MULTIPATH=n]
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>