nvme-pci: make PRP list DMA pools per-NUMA-node

NVMe commands with over 8 KB of discontiguous data allocate PRP list
pages from the per-nvme_device dma_pool prp_page_pool or prp_small_pool.
Each call to dma_pool_alloc() and dma_pool_free() takes the per-dma_pool
spinlock. These device-global spinlocks are a significant source of
contention when many CPUs are submitting to the same NVMe devices. On a
workload issuing 32 KB reads from 16 CPUs (8 hypertwin pairs) across 2
NUMA nodes to 23 NVMe devices, we observed 2.4% of CPU time spent in
_raw_spin_lock_irqsave called from dma_pool_alloc and dma_pool_free.

Ideally, the dma_pools would be per-hctx to minimize contention. But
that could impose considerable resource costs in a system with many NVMe
devices and CPUs.

As a compromise, allocate per-NUMA-node PRP list DMA pools. Map each
nvme_queue to the set of DMA pools corresponding to its device and its
hctx's NUMA node. This reduces the _raw_spin_lock_irqsave overhead by
about half, to 1.2%. Preventing the sharing of PRP list pages across
NUMA nodes also makes them cheaper to initialize.

Link: https://lore.kernel.org/linux-nvme/CADUfDZqa=OOTtTTznXRDmBQo1WrFcDw1hBA7XwM7hzJ-hpckcA@mail.gmail.com/T/#u
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-pci: factor out a nvme_init_hctx_common() helper

nvme_init_hctx() and nvme_admin_init_hctx() are very similar. In
preparation for adding more logic, factor out a nvme_init_hctx-common()
helper.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

dmapool: add NUMA affinity support

Introduce dma_pool_create_node(), like dma_pool_create() but taking an
additional NUMA node argument. Allocate struct dma_pool on the desired
node, and store the node on dma_pool for allocating struct dma_page.
Make dma_pool_create() an alias for dma_pool_create_node() with node set
to NUMA_NO_NODE.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-fc: do not reference lsrsp after failure

The lsrsp object is maintained by the LLDD. The lifetime of the lsrsp
object is implicit. Because there is no explicit cleanup/free call into
the LLDD, it is not safe to assume after xml_rsp_fails, that the lsrsp
is still valid. The LLDD could have freed the object already.

With the recent changes how fcloop tracks the resources, this is the
case. Thus don't access lsrsp after xml_rsp_fails.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: don't wait for lport cleanup

The lifetime of the fcloop_lsreq is not tight to the lifetime of the
host or target port, thus there is no need anymore to synchronize the
cleanup path anymore.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: add missing fcloop_callback_host_done

Add the missing fcloop_call_host_done calls so that the caller
frees resources when something goes wrong.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fc: take tgtport refs for portentry

Ensure that the tgtport is not going away as long portentry has a
pointer on it.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fc: free pending reqs on tgtport unregister

When nvmet_fc_unregister_targetport is called by the LLDD, it's not
possible to communicate with the host, thus all pending request will not
be process. Thus explicitly free them.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: drop response if targetport is gone

When the target port is gone, the lsrsp pointer is invalid. Thus don't
call the done function anymore instead just drop the response.

This happens when the target sends a disconnect association. After this
the target starts tearing down all resources and doesn't expect any
response.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: allocate/free fcloop_lsreq directly

fcloop depends on the host or the target to allocate the fcloop_lsreq
object. This means that the lifetime of the fcloop_lsreq is tied to
either the host or the target. Consequently, the host or the target must
cooperate during shutdown.

Unfortunately, this approach does not work well when the target forces a
shutdown, as there are dependencies that are difficult to resolve in a
clean way.

The simplest solution is to decouple the lifetime of the fcloop_lsreq
object by managing them directly within fcloop. Since this is not a
performance-critical path and only a small number of LS objects are used
during setup and cleanup, it does not significantly impact performance
to allocate them during normal operation.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: prevent double port deletion

The delete callback can be called either via the unregister function or
from the transport directly. Thus it is necessary ensure resources are
not freed multiple times.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: access fcpreq only when holding reqlock

The abort handling logic expects that the state and the fcpreq are only
accessed when holding the reqlock lock.

While at it, only handle the aborts in the abort handler.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: update refs on tfcp_req

Track the lifetime of the in-flight tfcp_req to ensure
the object is not freed too early.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: refactor fcloop_delete_local_port

Use the newly introduced fcloop_lport_lookup instead
of the open coded version.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: refactor fcloop_nport_alloc and track lport

The checks for a valid input values are mixed with the logic to insert a
newly allocated nport. Refactor the function so that first the checks
are done.

This allows to untangle the setup steps into a more linear form which
reduces the complexity of the functions.

Also start tracking lport when a lport is assigned to a nport. This
ensures, that the lport is not going away as long it is still referenced
by a nport.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: remove nport from list on last user

The nport object has an association with the rport and lport object,
that means we can only remove an nport object from the global nport_list
after the last user of an rport or lport is gone.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-fcloop: track ref counts for nports

A nport object is always used in association with targerport,
remoteport, tport and rport objects. Add explicit references for any of
the associated object. This ensures that nport is not removed too early
on shutdown sequences.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-auth: use SHASH_DESC_ON_STACK

Use SHASH_DESC_ON_STACK to avoid explicit allocation.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-auth: use SHASH_DESC_ON_STACK

Use SHASH_DESC_ON_STACK to avoid explicit allocation.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: simplify the nvmet_req_init() interface

Now that a submission queue holds a reference to its completion queue,
there is no need to pass the cq argument to nvmet_req_init(), so remove
it.

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: support completion queue sharing

The NVMe PCI transport specification allows for completion queues to be
shared by different submission queues.

This patch allows a submission queue to keep track of the completion queue
it is using with reference counting. As such, it can be ensured that a
completion queue is not deleted while a submission queue is actively
using it.

This patch enables completion queue sharing in the pci-epf target driver.
For fabrics drivers, completion queue sharing is not enabled as it is
not possible as per the fabrics specification. However, this patch
modifies the fabrics drivers to correctly integrate the new API that
supports completion queue sharing.

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: fabrics: add CQ init and destroy

With struct nvmet_cq now having a reference count, this patch amends the
target fabrics call chain to initialize and destroy/put a completion
queue.

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: cq: prepare for completion queue sharing

For the PCI transport, the NVMe specification allows submission queues
to share completion queues, however, this is not supported in the
current NVMe target implementation. This is a preparatory patch to allow
for completion queue (CQ) sharing between different submission queues
(SQ).

To support queue sharing, reference counting completion queues is
required. This patch adds the refcount_t field ref to struct nvmet_cq
coupled with respective nvmet_cq_init(), nvmet_cq_get(), nvmet_cq_put(),
nvmet_cq_is_deletable() and nvmet_cq_destroy() functions.

A CQ reference count is initialized with nvmet_cq_init() when a CQ is
created. Using nvmet_cq_get(), a reference to a CQ is taken when an SQ is
created that uses the respective CQ. Similarly. when an SQ is destroyed,
the reference count to the respective CQ from the SQ being destroyed is
decremented with nvmet_cq_put(). The last reference to a CQ is dropped
on a CQ deletion using nvmet_cq_put(), which invokes nvmet_cq_destroy()
to fully cleanup after the CQ. The helper function nvmet_cq_in_use() is
used to determine if any SQs are still using the CQ pending deletion.
In which case, the CQ must not be deleted. This should protect scenarios
where a bad host may attempt to delete a CQ without first having deleted
SQ(s) using that CQ.

Additionally, this patch adds an array of struct nvmet_cq to the
nvmet_ctrl structure. This allows for the controller to keep track of CQs
as they are created and destroyed, similar to the current tracking done
for SQs. The memory for this array is freed when the controller is freed.
A struct nvmet_ctrl reference is also added to the nvmet_cq structure to
allow for CQs to be removed from the controller whilst keeping the new
API similar to the existing API for SQs.

Sample callchain with CQ refcounting for the PCI endpoint target
(pci-epf):

i.   nvmet_execute_create_cq -> nvmet_pci_epf_create_cq
     -> nvmet_cq_create -> nvmet_cq_init [cq refcount=1]

ii.  nvmet_execute_create_sq -> nvmet_pci_epf_create_sq
     -> nvmet_sq_create -> nvmet_sq_init -> nvmet_cq_get [cq refcount=2]

iii. nvmet_execute_delete_sq - > nvmet_pci_epf_delete_sq ->
     -> nvmet_sq_destroy -> nvmet_cq_put [cq refcount 1]

iv.  nvmet_execute_delete_cq -> nvmet_pci_epf_delete_cq
     -> nvmet_cq_put [cq refcount 0]

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: add a helper function for cqid checking

This patch adds a new helper function nvmet_check_io_cqid(). It is to be
used when parsing host commands for IO CQ creation/deletion and IO SQ
creation to ensure that the specified IO completion queue identifier
(CQID) is not 0 (Admin queue ID). This is a check that already occurs in
the nvmet_execute_x() functions prior to nvmet_check_cqid.

With the addition of this helper function, the CQ ID checks in the
nvmet_execute_x() function can be removed, and instead simply call
nvmet_check_io_cqid() in place of nvmet_check_cqid().

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-auth: authenticate on admin queue only

Do not start authentication on I/O queues as it doesn't really add value,
and secure concatenation disallows it anyway.  Authentication commands on
I/O queues are not aborted, so the host may still run the authentication
protocol on I/O queues.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-auth: do not re-authenticate queues with no prior authentication

When sending 'connect' the queues can figure out from the return code
whether authentication is required or not. But reauthentication doesn't
disconnect the queues, so this check is not available.  Rather we need
to check whether the queue had been authenticated initially to figure
out if we need to reauthenticate.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet-tcp: switch to using the crc32c library

Now that the crc32c() library function directly takes advantage of
architecture-specific optimizations, it is unnecessary to go through the
crypto API.  Just use crc32c().  This is much simpler, and it improves
performance due to eliminating the crypto API overhead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvmet: replace strncpy with strscpy

The strncpy() function is deprecated for NUL-terminated strings as
explained in the "strncpy() on NUL-terminated strings" section of
Documentation/process/deprecated.rst.

The key issues are:
- strncpy() fails to guarantee NULL-termination when source > destination
- it unnecessarily zero-pads short strings, causing performance overhead

strscpy() is the proper replacement because:
- it guarantees NULL-termination
- it avoids redundant zero-padding
- it aligns with current kernel string-copying best practice

memcpy() was rejected because:
- NQN buffers (subsysnqn/hostnqn) are treated as NULL-terminated strings:
  - strcmp() usage in nvmet_host_allowed() (discovery.c)
  - strscpy() to copy subsysnqn in nvmet_execute_disc_identify()

seq_buf wasn't used because:
- this is a simple fixed-size buffer copy
- there is no need for progressive string construction features

Signed-off-by: Marcelo Moreira <marcelomoreira1905@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-tcp: open-code nvme_tcp_queue_request() for R2T

When handling an R2T PDU we short-circuit nvme_tcp_queue_request()
as we should not attempt to send consecutive PDUs. So open-code
nvme_tcp_queue_request() for R2T and drop the last argument.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

nvme-tcp: remove redundant check to ctrl->opts

When checking for secure concatenation we have already validated
that 'ctrl->opts' is set, so we can remove this check.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

nvme-loop: avoid -Wflex-array-member-not-at-end warning

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Move the conflicting declaration to the end of the structure. Notice
that `struct nvme_loop_iod` is a flexible structure --a structure
that contains a flexible-array member.

Fix the following warning:

drivers/nvme/target/loop.c:36:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

blk-mq: add a copyright notice to blk-mq-dma.c

blk-mq-dma.c was split from blk-merge.c which has no copyright notice,
but except for some boilerplate code and comments left from the old
version this is all my code, so add my copyright.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250513071433.836797-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-mq: move the DMA mapping code to a separate file

While working on the new DMA API I kept getting annoyed how it was placed
right in the middle of the bio splitting code in blk-merge.c.
Split it out into a separate file.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250513071433.836797-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

cdrom: Remove unnecessary NULL check before unregister_sysctl_table()

unregister_sysctl_table() checks for NULL pointers internally.
Remove unneeded NULL check here.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Link: https://lore.kernel.org/lkml/20250514032139.2317578-1-nichen@iscas.ac.cn
Reviewed-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/lkml/aCURuvkmz-fw3Nnp@equinox
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20250514223354.1429-2-phil@philpotter.co.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: fix elv_update_nr_hw_queues() to reattach elevator

When nr_hw_queues is updated, the elevator needs to be switched to
ensure that we exit elevator and reattach it to ensure that hctx->
sched_tags is correctly allocated for the new hardware queues.
However, elv_update_nr_hw_queues() currently only switches the
elevator if the queue is not registered. This is incorrect, as it
prevents reattaching the elevator after updating nr_hw_queues, which
in turn inhibits allocation of sched_tags.

Fix this by allowing the elevator switch if the queue is registered,
ensuring proper reattachment and resource allocation.

Fixes: 596dce110b7d ("block: simplify elevator reattachment for updating nr_hw_queues")
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250515134511.548270-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-throttle: silence !BLK_DEV_IO_TRACE variable warnings

If blk-throttle is enabled but blktrace is not, then the compiler will
notice that the following two variables are unused:

../block/blk-throttle.c: In function 'throtl_pending_timer_fn':
../block/blk-throttle.c:1153:30: warning: unused variable 'bio_cnt_w' [-Wunused-variable]
 1153 |                 unsigned int bio_cnt_w = sq_queued(sq, WRITE);
      |                              ^~~~~~~~~
../block/blk-throttle.c:1152:30: warning: unused variable 'bio_cnt_r' [-Wunused-variable]
 1152 |                 unsigned int bio_cnt_r = sq_queued(sq, READ);
      |                              ^~~~~~~~~

Silence that my annotating them with __maybe_unused.

Fixes: 28ad83b774a6 ("blk-throttle: Split the service queue")
Link: https://lore.kernel.org/all/20250515130830.9671-1-aishwarya.tcv@arm.com/
Reported-by: Aishwarya <aishwarya.tcv@arm.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

brd: avoid extra xarray lookups on first write

The xarray can return the previous entry at a location.  Use this
fact to simplify the brd code when there is no existing page at
a location.  This also slighly improves the handling of racy
discards as we now always have a page under RCU protection by the
time we are ready to copy the data.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250507060700.3929430-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Remove obsolete configs BLK_MQ_{PCI,VIRTIO}

Commit 9bc1e897a821 ("blk-mq: remove unused queue mapping helpers") makes
the two config options, BLK_MQ_PCI and BLK_MQ_VIRTIO, have no remaining
effect.

Remove the two obsolete config options.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250514065513.463941-1-lukas.bulwahn@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the same_page output argument to bvec_try_merge_page

bvec_try_merge_page currently returns if the added page fragment is
within the same page as the last page in the last current bio_vec.

This information is used by __bio_iov_iter_get_pages so that we always
have a single folio pin per page even when the page is split over
multiple __bio_iov_iter_get_pages calls.

Threading this through the entire lowlevel add page to bio logic is
annoying and inefficient and leads to less code sharing than otherwise
possible.  Instead add code to __bio_iov_iter_get_pages that checks if
the bio_vecs did not change and thus a merge into the last segment must
have happened, and if there is an offset into the page for the currently
added fragment, because if yes we must have already had a previous
fragment of the same page in the last bio_vec.  While this is still a bit
ugly, it keeps the logic in the one place that needs it and allows for
more code sharing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250512042354.514329-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Prevents the bps restricted io from entering the bps queue again

[BUG]
There has an issue of io delayed dispatch caused by io splitting. Consider
the following scenario:
1) If we set a BPS limit of 1MB/s and restrict the maximum IO size per
dispatch to 4KB, submitting -two- 1MB IO requests results in completion
times of 1s and 2s, which is expected.
2) However, if we additionally set an IOPS limit of 1,000,000/s with the
same BPS limit of 1MB/s, submitting -two- 1MB IO requests again results in
both completing in 2s, even though the IOPS constraint is being met.

[CAUSE]
This issue arises because BPS and IOPS currently share the same queue in
the blkthrotl mechanism:
1) This issue does not occur when only BPS is limited because the split IOs
return false in blk_should_throtl() and do not go through to throtl again.
2) For split IOs, even if they have been tagged with BIO_BPS_THROTTLED,
they still get queued alternately in the same list due to continuous
splitting and reordering. As a result, the two IO requests are both
completed at the 2-second mark, causing an unintended delay.
3) It is not difficult to imagine that in this scenario, if N 1MB IOs are
issued at once, all IOs will eventually complete together in N seconds.

[FIX]
With the queue separation introduced in the previous patches, we now have
separate BPS and IOPS queues. For IOs that have already passed the BPS
limitation, they do not need to re-enter the BPS queue and can directly
placed to the IOPS queue.

Since we have split the queues, when the IOPS queue is previously empty
and a new bio is added to the first qnode->bios_iops list in the
service_queue, we also need to update the disptime. This patch introduces
"THROTL_TG_IOPS_WAS_EMPTY" flag to mark it.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-8-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Split the service queue

This patch splits throtl_service_queue->nr_queued into "nr_queued_bps" and
"nr_queued_iops", allowing separate accounting of BPS and IOPS queued bios.
This prepares for future changes that need to check whether the BPS or IOPS
queues are empty.

To facilitate updating the number of IOs in the BPS and IOPS queues, the
addition logic will be moved from throtl_add_bio_tg() to
throtl_qnode_add_bio(), and similarly, the removal logic will be moved from
tg_dispatch_one_bio() to throtl_pop_queued().

And introduce sq_queued() to calculate the total sum of sq->nr_queued.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-7-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Split the blkthrotl queue

This patch splits the single queue into separate bps and iops queues. Now,
an IO request must first pass through the bps queue, then the iops queue,
and finally be dispatched. Due to the queue splitting, we need to modify
the throtl add/peek/pop function.

Additionally, the patch modifies the logic related to tg_dispatch_time().
If bio needs to wait for bps, function directly returns the bps wait time;
otherwise, it charges bps and returns the iops wait time so that bio can be
directly placed into the iops queue afterward. Note that this may lead to
more frequent updates to disptime, but the overhead is negligible for the
slow path.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-6-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Introduce flag "BIO_TG_BPS_THROTTLED"

Subsequent patches will split the single queue into separate bps and iops
queues. To prevent IO that has already passed through the bps queue at a
single tg level from being counted toward bps wait time again, we introduce
"BIO_TG_BPS_THROTTLED" flag. Since throttle and QoS operate at different
levels, we reuse the value as "BIO_QOS_THROTTLED".

We set this flag when charge bps and clear it when charge iops, as the bio
will move to the upper-level tg or be dispatched.

This patch does not involve functional changes.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-5-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Split throtl_charge_bio() into bps and iops functions

Split throtl_charge_bio() to facilitate subsequent patches that will
separately charge bps and iops after queue separation.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-4-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Refactor tg_dispatch_time by extracting tg_dispatch_bps/iops_time

tg_dispatch_time() contained both bps and iops throttling logic. We now
split its internal logic into tg_dispatch_bps/iops_time() to improve code
consistency for future separation of the bps and iops queues.

Besides, merge time_before() from caller into throtl_extend_slice() to make
code cleaner.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-3-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

blk-throttle: Rename tg_may_dispatch() to tg_dispatch_time()

tg_may_dispatch() can directly indicate whether bio can be dispatched by
returning the time to wait, without the need for the redundant "wait"
parameter. Remove it and modify the function's return type accordingly.

Since we have determined by the return time whether bio can be dispatched,
rename tg_may_dispatch() to tg_dispatch_time().

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Zizhi Wo <wozizhi@huaweicloud.com>
Link: https://lore.kernel.org/r/20250506020935.655574-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge tag 'md-6.16-20250513' of https://git./linux/kernel/git/mdraid/linux into for-6.16/block

Pull MD changes from Yu Kuai:

- Fix that normal IO can be starved by sync IO, found by mkfs on newly
  created large raid5, with some clean up patches for bdev inflight
  counters.

* tag 'md-6.16-20250513' of https://git.kernel.org/pub/scm/linux/kernel/git/mdraid/linux:
  md: clean up accounting for issued sync IO
  md: fix is_mddev_idle()
  md: add a new api sync_io_depth
  md: record dm-raid gendisk in mddev
  block: export API to get the number of bdev inflight IO
  block: clean up blk_mq_in_flight_rw()
  block: WARN if bdev inflight counter is negative
  block: reuse part_in_flight_rw for part_in_flight
  blk-mq: remove blk_mq_in_flight()

block: unfreeze queue if realloc tag set fails during nr_hw_queues update

In __blk_mq_update_nr_hw_queues(), the current sequence involves:

1. unregistering sysfs/debugfs attributes
2. freeze the queue
3. reallocating the tag set
4. updating the queue map
5. reallocating hardware contexts
6. updating the elevator (which unfreeze the queue again)
7. re-register sysfs/debugfs attributes

If tag set reallocation fails at step 3, the function skips steps 4–6
and proceeds directly to step 7, re-registering the sysfs/debugfs
attributes without unfreezing the queue first. This is incorrect and
can lead to a system hang or lockdep splat, as the queue remains frozen
and is never properly unfrozen.

This patch addresses the issue by explicitly unfreezing the queue before
re-registering the sysfs/debugfs attributes in the event of a tag set
reallocation failure.

Fixes: 9dc7a882ce96 ("block: move hctx debugfs/sysfs registering out of freezing queue")
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250512092952.135887-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

md: clean up accounting for issued sync IO

It's no longer used and can be removed, also remove the field
'gendisk->sync_io'.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-10-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

md: fix is_mddev_idle()

If sync_speed is above speed_min, then is_mddev_idle() will be called
for each sync IO to check if the array is idle, and inflight sync_io
will be limited if the array is not idle.

However, while mkfs.ext4 for a large raid5 array while recovery is in
progress, it's found that sync_speed is already above speed_min while
lots of stripes are used for sync IO, causing long delay for mkfs.ext4.

Root cause is the following checking from is_mddev_idle():

t1: submit sync IO: events1 = completed IO - issued sync IO
t2: submit next sync IO: events2  = completed IO - issued sync IO
if (events2 - events1 > 64)

For consequence, the more sync IO issued, the less likely checking will
pass. And when completed normal IO is more than issued sync IO, the
condition will finally pass and is_mddev_idle() will return false,
however, last_events will be updated hence is_mddev_idle() can only
return false once in a while.

Fix this problem by changing the checking as following:

1) mddev doesn't have normal IO completed;
2) mddev doesn't have normal IO inflight;
3) if any member disks is partition, and all other partitions doesn't
   have IO completed.

Also change rdev->last_events to unsigned long to cleanup type casting.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-9-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

md: add a new api sync_io_depth

Currently if sync speed is above speed_min and below speed_max,
md_do_sync() will wait for all sync IOs to be done before issuing new
sync IO, means sync IO depth is limited to just 1.

This limit is too low, in order to prevent sync speed drop conspicuously
after fixing is_mddev_idle() in the next patch, add a new api for
limiting sync IO depth, the default value is 32.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-8-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

md: record dm-raid gendisk in mddev

Following patch will use gendisk to check if there are normal IO
completed or inflight, to fix a problem in mdraid that foreground IO
can be starved by background sync IO in later patches.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-7-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

block: export API to get the number of bdev inflight IO

- rename part_in_{flight, flight_rw} to bdev_count_{inflight, inflight_rw}
- export bdev_count_inflight, to fix a problem in mdraid that foreground
  IO can be starved by background sync IO in later patches

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-6-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>

block: clean up blk_mq_in_flight_rw()

Also add comment for part_inflight_show() for the difference between
bio-based and rq-based device.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-4-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

block: WARN if bdev inflight counter is negative

Which means there is a bug for related bio-based disk driver, or blk-mq
for rq-based disk, it's better not to hide the bug.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-3-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>

block: reuse part_in_flight_rw for part_in_flight

They are almost identical, to make code cleaner.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-2-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>

blk-mq: remove blk_mq_in_flight()

After commit 7be835694dae ("block: fix that util can be greater than
100%"), it's not used and can be removed.

Link: https://lore.kernel.org/linux-raid/20250506124903.2540268-1-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>

block: move removing elevator after deleting disk->queue_kobj

When blk_unregister_queue() is called from add_disk() failure path,
there is race in registering/unregistering elevator queue kobject
from the two code paths, because commit 559dc11143eb ("block: move
elv_register[unregister]_queue out of elevator_lock") moves elevator
queue register/unregister out of elevator lock.

Fix the race by removing elevator after deleting disk->queue_kobj,
because kobject_del(&disk->queue_kobj) drains in-progress sysfs
show()/store() of all attributes.

Fixes: 559dc11143eb ("block: move elv_register[unregister]_queue out of elevator_lock")
Reported-by: Nilay Shroff <nilay@linux.ibm.com>
Suggested-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250508085807.3175112-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: don't quiesce queue for calling elevator_set_none()

blk_mq_freeze_queue() can't be called on quiesced queue, otherwise it may
never return if there is any queued requests.

Fix it by removing quiesce queue around elevator_set_none() because
elevator_switch() does quiesce queue in case that we need to switch
to none really.

Fixes: 1e44bedbc921 ("block: unifying elevator change")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250508085807.3175112-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs: aio: initialize .ki_write_stream of read-write request

AIO needs to initialize .ki_write_stream explicitly for read/write request,
otherwise random .ki_write_stream is used, and cause -EINVAL returned for
aio write randomly.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Kanchan Joshi <joshi.k@samsung.com>
Fixes: c27683da6406 ("block: expose write streams for block device nodes")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250507133328.3040255-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

hfsplus: use bdev_rw_virt in hfsplus_submit_bio

Replace the code building a bio from a kernel direct map address and
submitting it synchronously with the bdev_rw_virt helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs: use bdev_rw_virt in scrub_one_super

Replace the code building a bio from a kernel direct map address and
submitting it synchronously with the bdev_rw_virt helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-19-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

xfs: simplify building the bio in xlog_write_iclog

Use the bio_add_virt_nofail and bio_add_vmalloc helpers to abstract
away the details of the memory allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

xfs: simplify xfs_rw_bdev

Delegate to bdev_rw_virt when operating on non-vmalloc memory and use
bio_add_vmalloc_chunk to insulate xfs from the details of adding vmalloc
memory to a bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

xfs: simplify xfs_buf_submit_bio

Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
bio_add_virt_nofail helper implementing it and use bio_add_vmalloc
to insulate xfs from the details of adding vmalloc memory to a bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

dm-integrity: use bio_add_virt_nofail

Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
bio_add_virt_nofail helper implementing it, and do the same for the
similar pattern using bio_add_page for adding the first segment after
a bio allocation as that can't fail either.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

dm-bufio: use bio_add_virt_nofail

Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
bio_add_virt_nofail helper implementing it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

PM: hibernate: split and simplify hib_submit_io

Split hib_submit_io into a sync and async version.  The sync version is
a small wrapper around bdev_rw_virt which implements all the logic to
add a kernel direct mapping range to a bio and synchronously submits it,
while the async version is slightly simplified using the
bio_add_virt_nofail for adding the single range.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

zonefs: use bdev_rw_virt in zonefs_read_super

Switch zonefs_read_super to allocate the superblock buffer using kmalloc
which falls back to the page allocator for PAGE_SIZE allocation but
gives us a kernel virtual address and then use bdev_rw_virt to perform
the synchronous read into it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

gfs2: use bdev_rw_virt in gfs2_read_super

Switch gfs2_read_super to allocate the superblock buffer using kmalloc
which falls back to the page allocator for PAGE_SIZE allocation but
gives us a kernel virtual address and then use bdev_rw_virt to perform
the synchronous read into it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

rnbd-srv: use bio_add_virt_nofail

Use the bio_add_virt_nofail to add a single kernel virtual address
to a bio as that can't fail.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

bcache: use bio_add_virt_nofail

Convert the __bio_add_page(..., virt_to_page(), ...) pattern to the
bio_add_virt_nofail helper implementing it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: simplify bio_map_kern

Rewrite bio_map_kern using the new bio_add_* helpers and drop the
kerneldoc comment that is superfluous for an internal helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: pass the operation to bio_{map,copy}_kern

That way the bio can be allocated with the right operation already
set and there is no need to pass the separated 'reading' argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the q argument from blk_rq_map_kern

Remove the q argument from blk_rq_map_kern and the internal helpers
called by it as the queue can trivially be derived from the request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a bio_add_vmalloc helpers

Add a helper to add a vmalloc region to a bio, abstracting away the
vmalloc addresses from the underlying pages and another one wrapping
it for the simple case where all data fits into a single bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a bio_add_max_vecs helper

Add a helper to check how many bio_vecs are needed to add a kernel
virtual address range to a bio, accounting for the always contiguous
direct mapping and vmalloc mappings that usually need a bio_vec
per page sized chunk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a bdev_rw_virt helper

Add a helper to perform synchronous I/O on a kernel direct map range.
Currently this is implemented in various places in usually not very
efficient ways, so provide a generic helper instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a bio_add_virt_nofail helper

Add a helper to add a directly mapped kernel virtual address to a
bio so that callers don't have to convert to pages or folios.

For now only the _nofail variant is provided as that is what all the
obvious callers want.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250507120451.4000627-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: fix warning on 'make htmldocs'

Fix the following warning when running 'make htmldocs':

+WARNING: include/linux/blk-mq.h:532 struct member 'update_nr_hwq_lock' not described in 'blk_mq_tag_set'

Fixes: 98e68f67020c ("block: prevent adding/deleting disk during updating nr_hw_queues")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20250507163220.00141d77@canb.auug.org.au/
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250507092537.3009112-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: fix incorrect sizeof

The plid array, head->plids, is meant to store placement IDs, each of
type u16. But its size has been incorrectly calculated, as the size of
the pointer is being used instead of the size of the object it points
to.

Use the sizeof(*head->plids) in kcalloc so that we don't allocate extra.

Fixes: 38e8397dde63 ("nvme: use fdp streams if write stream is provided")
Reported-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: fix write_stream_granularity initialization

write_stream_granularity is set to max(info->runs, U32_MAX), which means
that any RUNS value less than 2 ** 32 becomes U32_MAX, and any larger
value is silently truncated to an unsigned int.

Use min() instead to provide the correct semantics, capping RUNS values
at U32_MAX.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 30b5f20bb2dd ("nvme: register fdp parameters with the block layer")
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250506175413.1936110-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: use fdp streams if write stream is provided

Maps a user requested write stream to an FDP placement ID if possible.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-12-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: register fdp parameters with the block layer

Register the device data placement limits if supported. This is just
registering the limits with the block layer. Nothing beyond reporting
these attributes is happening in this patch.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-11-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: add FDP definitions

Add the config feature result, config log page, and management receive
commands needed for FDP.

Partially based on a patch from Kanchan Joshi <joshi.k@samsung.com>.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-10-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: pass a void pointer to nvme_get/set_features for the result

That allows passing in structures instead of the u32 result, and thus
reduce the amount of bit shifting and masking required to parse the
result.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-9-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

nvme: add a nvme_get_log_lsi helper

For log pages that need to pass in a LSI value, while at the same time
not touching all the existing nvme_get_log callers.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-8-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: enable per-io write streams

Allow userspace to pass a per-I/O write stream in the SQE:

      __u8 write_stream;

The __u8 type matches the size the filesystems and block layer support.

Application can query the supported values from the block devices
max_write_streams sysfs attribute. Unsupported values are ignored by
file operations that do not support write streams or rejected with an
error by those that support them.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-7-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: expose write streams for block device nodes

Use the per-kiocb write stream if provided, or map temperature hints to
write streams (which is a bit questionable, but this shows how it is
done).

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[kbusch: removed statx reporting]
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-6-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: introduce a write_stream_granularity queue limit

Export the granularity that write streams should be discarded with,
as it is essential for making good use of them.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-5-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: introduce max_write_streams queue limit

Drivers with hardware that support write streams need a way to export how
many are available so applications can generically query this.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
[hch: renamed hints to streams, removed stacking]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-4-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add a bi_write_stream field

Add the ability to pass a write stream for placement control in the bio.
The new field fits in an existing hole, so does not change the size of
the struct.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-3-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs: add a write stream field to the kiocb

Prepare for io_uring passthrough of write streams. The write stream
field in the kiocb structure fits into an existing 2-byte hole, so its
size is not changed.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-2-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: only update request sector if needed

In case of a ZONE APPEND write, regardless of native ZONE APPEND or the
emulation layer in the zone write plugging code, the sector the data got
written to by the device needs to be updated in the bio.

At the moment, this is done for every native ZONE APPEND write and every
request that is flagged with 'BIO_ZONE_WRITE_PLUGGING'. But thus
superfluously updates the sector for regular writes to a zoned block
device.

Check if a bio is a native ZONE APPEND write or if the bio is flagged as
'BIO_EMULATES_ZONE_APPEND', meaning the block layer's zone write plugging
code handles the ZONE APPEND and translates it into a regular write and
back. Only if one of these two criterion is met, update the sector in the
bio upon completion.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/dea089581cb6b777c1cd1500b38ac0b61df4b2d1.1746530748.git.jth@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move wbt_enable_default() out of queue freezing from sched ->exit()

scheduler's ->exit() is called with queue frozen and elevator lock is held, and
wbt_enable_default() can't be called with queue frozen, otherwise the
following lockdep warning is triggered:

#6 (&q->rq_qos_mutex){+.+.}-{4:4}:
#5 (&eq->sysfs_lock){+.+.}-{4:4}:
#4 (&q->elevator_lock){+.+.}-{4:4}:
#3 (&q->q_usage_counter(io)#3){++++}-{0:0}:
#2 (fs_reclaim){+.+.}-{0:0}:
#1 (&sb->s_type->i_mutex_key#3){+.+.}-{4:4}:
#0 (&q->debugfs_mutex){+.+.}-{4:4}:

Fix the issue by moving wbt_enable_default() out of bfq's exit(), and
call it from elevator_change_done().

Meantime add disk->rqos_state_mutex for covering wbt state change, which
matches the purpose more than ->elevator_lock.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-26-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move hctx cpuhp add/del out of queue freezing

Move hctx cpuhp add/del out of queue freezing for not connecting freeze
lock with cpuhp locks, then lockdep warning can be avoided.

This way is safe because both needn't queue to be frozen and scheduler
switch isn't allowed, with same reason for moving hctx debugfs/sysfs
register out of queue freeze.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-25-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: don't acquire ->elevator_lock in blk_mq_map_swqueue and blk_mq_realloc_hw_ctxs

Both blk_mq_map_swqueue() and blk_mq_realloc_hw_ctxs() are called before
the request queue is added to tagset list, so the two won't run concurrently
with blk_mq_update_nr_hw_queues().

When the two functions are only called from queue initialization or
blk_mq_update_nr_hw_queues(), elevator switch can't happen.

So remove ->elevator_lock uses from the two functions.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-24-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move hctx debugfs/sysfs registering out of freezing queue

Move hctx debugfs/sysfs register out of freezing queue in
__blk_mq_update_nr_hw_queues(), so that the following lockdep dependency
can be killed:

#2 (&q->q_usage_counter(io)#16){++++}-{0:0}:
#1 (fs_reclaim){+.+.}-{0:0}:
#0 (&sb->s_type->i_mutex_key#3){+.+.}-{4:4}: //debugfs

And registering/un-registering hctx debugfs/sysfs does not require queue to
be frozen:

- hctx sysfs attributes show() are drained when removing kobject, and
  there isn't store() implementation for hctx sysfs attributes

- debugfs entry read() is drained too when removing debugfs directory,
  and there isn't write() implementation for hctx debugfs too

- so it is safe to register/unregister hctx sysfs/debugfs without
  freezing queue because the cod paths changes nothing, and we just
  need to keep hctx live

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-23-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move elv_register[unregister]_queue out of elevator_lock

Move elv_register[unregister]_queue out of ->elevator_lock & queue freezing,
so we can kill many lockdep warnings.

elv_register[unregister]_queue() is serialized, and just dealing with sysfs/
debugfs things, no need to be done with queue frozen:

- when it is called from adding disk, elevator switch isn't possible
  because ->queue_kobj isn't added yet

- when it is called from deleting disk, disable_elv_switch() is
  responsible for preventing new elevator switch and draining old
  elevator switch.

- when it is called from blk_mq_update_nr_hw_queues(), adding/removing
  disk and elevator switch can't be allowed or in-progress

With this change, elevator's ->exit() is called before calling
elv_unregister_queue, then user may call into ->show()/store() of elevator's
sysfs attributes, and we have covered this issue by adding `ELEVATOR_FLAG_DYNG`.

For blk-mq debugfs, hctx->sched_tags is always checked with ->elevator_lock by
debugfs code, meantime hctx->sched_tags is updated with ->elevator_lock, so
there isn't such issue.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-22-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add new helper for disabling elevator switch when deleting disk

Add new helper disable_elv_switch() and new flag QUEUE_FLAG_NO_ELV_SWITCH
for disabling elevator switch before deleting disk:

- originally flag QUEUE_FLAG_REGISTERED is added for preventing elevator
switch during removing disk, but this flag has been used widely for
other purposes, so add one new flag for disabling elevator switch only

- for avoiding deadlock risk, we have to move elevator queue
register/unregister out of elevator lock and queue freeze, which will be
done in next patch. However, this way adds small race window between elevator
switch and deleting ->queue_kobj, in which elevator queue register/unregister
could be run concurrently. The added helper will be used for avoiding the race
in the following patch.

- drain in-progress elevator switch before deleting disk

Suggested-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-21-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>