Pull block fixes from Jens Axboe:
 "Main thing here is the fix for the regression in flush handling which
  caused IO hangs/stalls for a few reporters. Hopefully that should all
  be sorted out now. Outside of that, just a few minor fixes for issues
  that were introduced in this cycle"

* tag 'block-6.5-2023-08-19' of git://git.kernel.dk/linux:
  blk-mq: release scheduler resource when request completes
  blk-crypto: dynamically allocate fallback profile
  blk-cgroup: hold queue_lock when removing blkg->q_node
  drivers/rnbd: restore sysfs interface to rnbd-client

Chuck reported [1] an IO hang problem on NFS exports that reside on SATA
devices and bisected to commit 615939a2ae73 ("blk-mq: defer to the normal
submission path for post-flush requests").

We analysed the IO hang problem, found there are two postflush requests
waiting for each other.

The first postflush request completed the REQ_FSEQ_DATA sequence, so go to
the REQ_FSEQ_POSTFLUSH sequence and added in the flush pending list, but
failed to blk_kick_flush() because of the second postflush request which
is inflight waiting in scheduler queue.

The second postflush waiting in scheduler queue can't be dispatched because
the first postflush hasn't released scheduler resource even though it has
completed by itself.

Fix it by releasing scheduler resource when the first postflush request
completed, so the second postflush can be dispatched and completed, then
make blk_kick_flush() succeed.

While at it, remove the check for e->ops.finish_request, as all
schedulers set that. Reaffirm this requirement by adding a WARN_ON_ONCE()
at scheduler registration time, just like we do for insert_requests and
dispatch_request.

[1] https://lore.kernel.org/all/7A57C7AE-A51A-4254-888B-FE15CA21F9E9@oracle.com/

Link: https://lore.kernel.org/linux-block/20230819031206.2744005-1-chengming.zhou@linux.dev/
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202308172100.8ce4b853-oliver.sang@intel.com
Fixes: 615939a2ae73 ("blk-mq: defer to the normal submission path for post-flush requests")
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20230813152325.3017343-1-chengming.zhou@linux.dev
[axboe: folded in incremental fix and added tags]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk_crypto_profile_init() calls lockdep_register_key(), which warns and
does not register if the provided memory is a static object.
blk-crypto-fallback currently has a static blk_crypto_profile and calls
blk_crypto_profile_init() thereupon, resulting in the warning and
failure to register.

Fortunately it is simple enough to use a dynamically allocated profile
and make lockdep function correctly.

Fixes: 2fb48d88e77f ("blk-crypto: use dynamic lock class for blk_crypto_profile::lock")
Cc: stable@vger.kernel.org
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230817141615.15387-1-sweettea-kernel@dorminy.me
Signed-off-by: Jens Axboe <axboe@kernel.dk>

When blkg is removed from q->blkg_list from blkg_free_workfn(), queue_lock
has to be held, otherwise, all kinds of bugs(list corruption, hard lockup,
..) can be triggered from blkg_destroy_all().

Fixes: f1c006f1c685 ("blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()")
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: xiaoli feng <xifeng@redhat.com>
Cc: Chunyu Hu <chuhu@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230817141751.1128970-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull block fixes from Jens Axboe:

 - NVMe pull request via Keith:
      - Fixes for request_queue state (Ming)
      - Another uuid quirk (August)

 - RCU poll fix for NVMe (Ming)

 - Fix for an IO stall with polled IO (me)

 - Fix for blk-iocost stats enable/disable accounting (Chengming)

 - Regression fix for large pages for zram (Christoph)

* tag 'block-6.5-2023-08-11' of git://git.kernel.dk/linux:
  nvme: core: don't hold rcu read lock in nvme_ns_chr_uring_cmd_iopoll
  blk-iocost: fix queue stats accounting
  block: don't make REQ_POLLED imply REQ_NOWAIT
  block: get rid of unused plug->nowait flag
  zram: take device and not only bvec offset into account
  nvme-pci: add NVME_QUIRK_BOGUS_NID for Samsung PM9B1 256G and 512G
  nvme-rdma: fix potential unbalanced freeze & unfreeze
  nvme-tcp: fix potential unbalanced freeze & unfreeze
  nvme: fix possible hang when removing a controller during error recovery

The q->stats->accounting is not only used by iocost, but iocost only
increase this counter, never decrease it. So queue stats accounting
will always enabled after using iocost once.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230804070609.31623-1-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Normally these two flags do go together, as the issuer of polled IO
generally cannot wait for resources that will get freed as part of IO
completion. This is because that very task is the one that will complete
the request and free those resources, hence that would introduce a
deadlock.

But it is possible to have someone else issue the polled IO, eg via
io_uring if the request is punted to io-wq. For that case, it's fine to
have the task block on IO submission, as it is not the same task that
will be completing the IO.

It's completely up to the caller to ask for both polled and nowait IO
separately! If we don't allow polled IO where IOCB_NOWAIT isn't set in
the kiocb, then we can run into repeated -EAGAIN submissions and not
make any progress.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This was introduced to add a plug based way of signaling nowait issues,
but we have since moved on from that. Kill the old dead code, nobody is
setting it anymore.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull block fixes from Jens Axboe:

 - Fix for loop regressions (Mauricio)

 - Fix a potential stall with batched wakeups in sbitmap (David)

 - Fix for stall with recursive plug flushes (Ross)

 - Skip accounting of empty requests for blk-iocost (Chengming)

 - Remove a dead field in struct blk_mq_hw_ctx (Chengming)

* tag 'block-6.5-2023-07-21' of git://git.kernel.dk/linux:
  loop: do not enforce max_loop hard limit by (new) default
  loop: deprecate autoloading callback loop_probe()
  sbitmap: fix batching wakeup
  blk-iocost: skip empty flush bio in iocost
  blk-mq: delete dead struct blk_mq_hw_ctx->queued field
  blk-mq: Fix stall due to recursive flush plug

The flush bio may have data, may have no data (empty flush), we couldn't
calculate cost for empty flush bio. So we'd better just skip it for now.

Another side effect is that empty flush bio's bio_end_sector() is 0, cause
iocg->cursor reset to 0, may break the cost calculation of other bios.

This isn't good enough, since flush bio still consume the device bandwidth,
but flush request is special, can be merged randomly in the flush state
machine, we don't know how to calculate cost for it for now.

Its completion time also has flaws, which may include the pre-flush or
post-flush completion time, but I don't know if we need to fix that and
how to fix it.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230720121441.1408522-1-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>