Max Gurtovoy [Wed, 22 Sep 2021 21:55:37 +0000 (00:55 +0300)]
nvmet-rdma: implement get_max_queue_size controller op
Limit the maximal queue size for RDMA controllers. Today, the target
reports a limit of 1024 and this limit isn't valid for some of the RDMA
based controllers. For now, limit RDMA transport to 128 entries (the
max queue depth configured for Linux NVMe/RDMA host).
Future general solution should use RDMA/core API to calculate this size
according to device capabilities and number of WRs needed per NVMe IO
request.
Reported-by: Mark Ruijter <mruijter@primelogic.nl> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Max Gurtovoy [Wed, 22 Sep 2021 21:55:36 +0000 (00:55 +0300)]
nvmet: add get_max_queue_size op for controllers
Some transports, such as RDMA, would like to set the queue size
according to device/port/ctrl characteristics. Add a new nvmet transport
op that is called during ctrl initialization. This will not effect
transports that don't implement this option.
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Max Gurtovoy [Wed, 22 Sep 2021 21:55:35 +0000 (00:55 +0300)]
nvme-rdma: limit the maximal queue size for RDMA controllers
Corrent limit of 1024 isn't valid for some of the RDMA based ctrls. In
case the target expose a cap of larger amount of entries (e.g. 1024),
the initiator may fail to create a QP with this size. Thus limit to a
value that works for all RDMA adapters.
Future general solution should use RDMA/core API to calculate this size
according to device capabilities and number of WRs needed per NVMe IO
request.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Israel Rukshin [Wed, 6 Oct 2021 08:09:45 +0000 (08:09 +0000)]
nvmet-tcp: fix use-after-free when a port is removed
When removing a port, all its controllers are being removed, but there
are queues on the port that doesn't belong to any controller (during
connection time). This causes a use-after-free bug for any command
that dereferences req->port (like in nvmet_alloc_ctrl). Those queues
should be destroyed before freeing the port via configfs. Destroy
the remaining queues after the accept_work was cancelled guarantees
that no new queue will be created.
Signed-off-by: Israel Rukshin <israelr@nvidia.com> Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Israel Rukshin [Wed, 6 Oct 2021 08:09:44 +0000 (08:09 +0000)]
nvmet-rdma: fix use-after-free when a port is removed
When removing a port, all its controllers are being removed, but there
are queues on the port that doesn't belong to any controller (during
connection time). This causes a use-after-free bug for any command
that dereferences req->port (like in nvmet_alloc_ctrl). Those queues
should be destroyed before freeing the port via configfs. Destroy the
remaining queues after the RDMA-CM was destroyed guarantees that no
new queue will be created.
Signed-off-by: Israel Rukshin <israelr@nvidia.com> Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Israel Rukshin [Wed, 6 Oct 2021 08:09:43 +0000 (08:09 +0000)]
nvmet: fix use-after-free when a port is removed
When a port is removed through configfs, any connected controllers
are starting teardown flow asynchronously and can still send commands.
This causes a use-after-free bug for any command that dereferences
req->port (like in nvmet_parse_io_cmd).
To fix this, wait for all the teardown scheduled works to complete
(like release_work at rdma/tcp drivers). This ensures there are no
active controllers when the port is eventually removed.
Signed-off-by: Israel Rukshin <israelr@nvidia.com> Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Saurav Kashyap [Mon, 23 Aug 2021 12:56:48 +0000 (05:56 -0700)]
nvme-fc: add support for ->map_queues
NVMe FC don't have support for map queues, unlike the PCI, RDMA and TCP
transports. Add a ->map_queues callout for the LLDDs to provide such
functionality.
Hannes Reinecke [Wed, 6 Oct 2021 09:13:13 +0000 (11:13 +0200)]
nvme: generate uevent once a multipath namespace is operational again
When fast_io_fail_tmo is set I/O will be aborted while recovery is
still ongoing. This causes MD to set the namespace to failed, and
no futher I/O will be submitted to that namespace.
However, once the recovery succeeds and the namespace becomes
operational again the NVMe subsystem doesn't send a notification,
so MD cannot automatically reinstate operation and requires
manual interaction.
This patch will send a KOBJ_CHANGE uevent per multipathed namespace
once the underlying controller transitions to LIVE, allowing an automatic
MD reassembly with these udev rules:
UUID_LINK=$(readlink /dev/disk/by-id/md-uuid-${MD_UUID})
MD_DEVNAME=${UUID_LINK##*/}
export $(${MDADM} --detail --export /dev/${MD_DEVNAME})
if [ -z "${MD_METADATA}" ] ; then
exit 1
fi
if [ $(cat /sys/block/${MD_DEVNAME}/md/degraded) != 1 ]; then
echo "${MD_DEVNAME}: array not degraded, nothing to do"
exit 0
fi
MD_STATE=$(cat /sys/block/${MD_DEVNAME}/md/array_state)
if [ ${MD_STATE} != "clean" ] ; then
echo "${MD_DEVNAME}: array state ${MD_STATE}, cannot re-add"
exit 1
fi
MD_VARNAME="MD_DEVICE_dev_${DEVNAME##*/}_ROLE"
if [ ${!MD_VARNAME} = "spare" ] ; then
${MDADM} --manage /dev/${MD_DEVNAME} --re-add ${DEVNAME}
fi
Changes to v2:
- Add udev rules example to description
Changes to v1:
- use disk_uevent() as suggested by hch
Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
Michael Schmitz [Tue, 19 Oct 2021 06:13:21 +0000 (19:13 +1300)]
block: ataflop: fix breakage introduced at blk-mq refactoring
Refactoring of the Atari floppy driver when converting to blk-mq
has broken the state machine in not-so-subtle ways:
finish_fdc() must be called when operations on the floppy device
have completed. This is crucial in order to relase the ST-DMA
lock, which protects against concurrent access to the ST-DMA
controller by other drivers (some DMA related, most just related
to device register access - broken beyond compare, I know).
When rewriting the driver's old do_request() function, the fact
that finish_fdc() was called only when all queued requests had
completed appears to have been overlooked. Instead, the new
request function calls finish_fdc() immediately after the last
request has been queued. finish_fdc() executes a dummy seek after
most requests, and this overwrites the state machine's interrupt
hander that was set up to wait for completion of the read/write
request just prior. To make matters worse, finish_fdc() is called
before device interrupts are re-enabled, making certain that the
read/write interupt is missed.
Shifting the finish_fdc() call into the read/write request
completion handler ensures the driver waits for the request to
actually complete. With a queue depth of 2, we won't see long
request sequences, so calling finish_fdc() unconditionally just
adds a little overhead for the dummy seeks, and keeps the code
simple.
While we're at it, kill ataflop_commit_rqs() which does nothing
but run finish_fdc() unconditionally, again likely wiping out an
in-flight request.
There is a problem that nbd_handle_reply() might access freed request:
1) At first, a normal io is submitted and completed with scheduler:
internel_tag = blk_mq_get_tag -> get tag from sched_tags
blk_mq_rq_ctx_init
sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag]
...
blk_mq_get_driver_tag
__blk_mq_get_driver_tag -> get tag from tags
tags->rq[tag] = sched_tag->static_rq[internel_tag]
So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing
to the request: sched_tags->static_rq[internal_tag]. Even if the
io is finished.
2) nbd server send a reply with random tag directly:
commit 6a468d5990ec ("nbd: don't start req until after the dead
connection logic") move blk_mq_start_request() from nbd_queue_rq()
to nbd_handle_cmd() to skip starting request if the connection is
dead. However, request is still started in other error paths.
Currently, blk_mq_end_request() will be called immediately if
nbd_queue_rq() failed, thus start request in such situation is
useless. So remove blk_mq_start_request() from error paths in
nbd_handle_cmd().
nbd: make sure request completion won't concurrent
commit cddce0116058 ("nbd: Aovid double completion of a request")
try to fix that nbd_clear_que() and recv_work() can complete a
request concurrently. However, the problem still exists:
t1 t2 t3
nbd_disconnect_and_put
flush_workqueue
recv_work
blk_mq_complete_request
blk_mq_complete_request_remote -> this is true
WRITE_ONCE(rq->state, MQ_RQ_COMPLETE)
blk_mq_raise_softirq
blk_done_softirq
blk_complete_reqs
nbd_complete_rq
blk_mq_end_request
blk_mq_free_request
WRITE_ONCE(rq->state, MQ_RQ_IDLE)
nbd_clear_que
blk_mq_tagset_busy_iter
nbd_clear_req
__blk_mq_free_request
blk_mq_put_tag
blk_mq_complete_request -> complete again
There are three places where request can be completed in nbd:
recv_work(), nbd_clear_que() and nbd_xmit_timeout(). Since they
all hold cmd->lock before completing the request, it's easy to
avoid the problem by setting and checking a cmd flag.
nbd: don't handle response without a corresponding request message
While handling a response message from server, nbd_read_stat() will
try to get request by tag, and then complete the request. However,
this is problematic if nbd haven't sent a corresponding request
message:
Xiao Ni [Wed, 13 Oct 2021 14:59:33 +0000 (22:59 +0800)]
md: update superblock after changing rdev flags in state_store
When the in memory flag is changed, we need to persist the change in the
rdev superblock flags. This is needed for "writemostly" and "failfast".
Reviewed-by: Li Feng <fengli@smartx.com> Signed-off-by: Xiao Ni <xni@redhat.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Guoqing Jiang [Mon, 4 Oct 2021 15:34:48 +0000 (23:34 +0800)]
md/raid1: only allocate write behind bio for WriteMostly device
Commit 6607cd319b6b91bff94e90f798a61c031650b514 ("raid1: ensure write
behind bio has less than BIO_MAX_VECS sectors") tried to guarantee the
size of behind bio is not bigger than BIO_MAX_VECS sectors.
Unfortunately the same calltrace still could happen since an array could
enable write-behind without write mostly device.
To match the manpage of mdadm (which says "write-behind is only attempted
on drives marked as write-mostly"), we need to check WriteMostly flag to
avoid such unexpected behavior.
Christoph Hellwig [Wed, 1 Sep 2021 11:38:32 +0000 (13:38 +0200)]
md: extend disks_mutex coverage
disks_mutex is intended to serialize md_alloc. Extended it to also cover
the kobject_uevent call and getting the sysfs dirent to help reducing
error handling complexity.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Christoph Hellwig [Wed, 1 Sep 2021 11:38:31 +0000 (13:38 +0200)]
md: add the bitmap group to the default groups for the md kobject
Replace the deprecated default_attrs with the default_groups mechanism,
and add the always visible bitmap group to the groups created add
kobject_add time.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Luis Chamberlain [Wed, 1 Sep 2021 11:38:30 +0000 (13:38 +0200)]
md: add error handling support for add_disk()
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.
We just do the unwinding of what was not done before, and are
sure to unlock prior to bailing.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Sat, 2 Oct 2021 01:23:26 +0000 (19:23 -0600)]
swim3: add missing major.h include
swim3 got this through blkdev.h previously, but blkdev.h is not including
it anymore. Include it specifically for the driver, otherwise FLOPPY_MAJOR
is undefined and breaks the compile on PPC if swim3 is configured.
Fixes: b81e0c2372e6 ("block: drop unused includes in <linux/genhd.h>") Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Signed-off-by: Jens Axboe <axboe@kernel.dk>
Luis Chamberlain [Mon, 27 Sep 2021 22:03:01 +0000 (15:03 -0700)]
block/ataflop: provide a helper for cleanup up an atari disk
Instead of using two separate code paths for cleaning up an atari disk,
use one. We take the more careful approach to check for *all* disk
types, as is done on exit. The init path didn't have that check as
the alternative disk types are only probed for later, they are not
initialized by default.
Luis Chamberlain [Mon, 27 Sep 2021 22:03:00 +0000 (15:03 -0700)]
block/ataflop: add registration bool before calling del_gendisk()
The ataflop assumes del_gendisk() is safe to call, this is only
true because add_disk() does not return a failure, but that will
change soon. And so, before we get to adding error handling for
that case, let's make sure we keep track of which disks actually
get registered. Then we use this to only call del_gendisk for them.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:58 +0000 (15:02 -0700)]
swim: add error handling support for add_disk()
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.
Since we have a caller to do our unwinding for the disk,
and this is already dealt with safely we can re-use our
existing error path goto label which already deals with
the cleanup.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:57 +0000 (15:02 -0700)]
swim: add a floppy registration bool which triggers del_gendisk()
Instead of calling del_gendisk() on exit alone, let's add
a registration bool to the floppy disk state, this way this can
be done on the shared caller, swim_cleanup_floppy_disk().
This will be more useful in subsequent patches. Right now, this
just shuffles functionality out to a helper in a safe way.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:56 +0000 (15:02 -0700)]
swim: add helper for disk cleanup
Disk cleanup can be shared between exit and bringup. Use a
helper to do the work required. The only functional change at
this point is we're being overly paraoid on exit to check for
a null disk as well now, and this should be safe.
We'll later expand on this, this change just makes subsequent
changes easier to read.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:54 +0000 (15:02 -0700)]
amiflop: add error handling support for add_disk()
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling. The caller for fd_alloc_disk() deals with
the rest of the cleanup like the tag.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:52 +0000 (15:02 -0700)]
floppy: fix calling platform_device_unregister() on invalid drives
platform_device_unregister() should only be called when
a respective platform_device_register() is called. However
the floppy driver currently allows failures when registring
a drive and a bail out could easily cause an invalid call
to platform_device_unregister() where it was not intended.
Fix this by adding a bool to keep track of when the platform
device was registered for a drive.
This does not fix any known panic / bug. This issue was found
through code inspection while preparing the driver to use the
up and coming support for device_add_disk() error handling.
From what I can tell from code inspection, chances of this
ever happening should be insanely small, perhaps OOM.
Luis Chamberlain [Mon, 27 Sep 2021 22:02:50 +0000 (15:02 -0700)]
floppy: fix add_disk() assumption on exit due to new developments
After the patch titled "floppy: use blk_mq_alloc_disk and
blk_cleanup_disk" the floppy driver was modified to allocate
the blk_mq_alloc_disk() which allocates the disk with the
queue. This is further clarified later with the patch titled
"block: remove alloc_disk and alloc_disk_node". This clarifies
that:
Most drivers should use and have been converted to use
blk_alloc_disk and blk_mq_alloc_disk. Only the scsi
ULPs and dasd still allocate a disk separately from the
request_queue so don't bother with convenience macros for
something that should not see significant new users and
remove these wrappers.
And then we have the patch titled, "block: hold a request_queue
reference for the lifetime of struct gendisk" which ensures
that a queue is *always* present for sure during the entire
lifetime of a disk.
In the floppy driver's case then the disk always comes with the
queue. So even if even if the queue was cleaned up on exit, putting
the disk *is* still required, and likewise, blk_cleanup_queue() on
a null queue should not happen now as disk->queue is valid from
disk allocation time on.
Automatic backport code scrapers should hopefully not cherry pick
this patch as a stable fix candidate without full due dilligence to
ensure all the work done on the block layer to make this happen is
merged first.
Luis Chamberlain [Mon, 27 Sep 2021 22:01:55 +0000 (15:01 -0700)]
block/sx8: add error handling support for add_disk()
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.
A completion is used to notify the initial probe what is
happening and so we must defer error handling on completion.
Do this by remembering the error and using the shared cleanup
function.
The tags are shared and so are hanlded later for the
driver already.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
There's currently no way to experiment with polled IO with null_blk,
which seems like an oversight. This patch adds support for polled IO.
We keep a list of issued IOs on submit, and then process that list
when mq_ops->poll() is invoked.
A new parameter is added, poll_queues. It defaults to 1 like the
submit queues, meaning we'll have 1 poll queue available.
Jens Axboe [Mon, 18 Oct 2021 14:45:39 +0000 (08:45 -0600)]
nvme: wire up completion batching for the IRQ path
Trivial to do now, just need our own io_comp_batch on the stack and pass
that in to the usual command completion handling.
I pondered making this dependent on how many entries we had to process,
but even for a single entry there's no discernable difference in
performance or latency. Running a sync workload over io_uring:
Jens Axboe [Tue, 12 Oct 2021 15:28:46 +0000 (09:28 -0600)]
io_uring: utilize the io batching infrastructure for more efficient polled IO
Wire up using an io_comp_batch for f_op->iopoll(). If the lower stack
supports it, we can handle high rates of polled IO more efficiently.
This raises the single core efficiency on my system from ~6.1M IOPS to
~6.6M IOPS running a random read workload at depth 128 on two gen2
Optane drives.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Fri, 8 Oct 2021 11:59:37 +0000 (05:59 -0600)]
nvme: add support for batched completion of polled IO
Take advantage of struct io_comp_batch, if passed in to the nvme poll
handler. If it's set, rather than complete each request individually
inline, store them in the io_comp_batch list. We only do so for requests
that will complete successfully, anything else will be completed inline as
before.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Fri, 8 Oct 2021 11:50:46 +0000 (05:50 -0600)]
block: add support for blk_mq_end_request_batch()
Instead of calling blk_mq_end_request() on a single request, add a helper
that takes the new struct io_comp_batch and completes any request stored
in there.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Mon, 18 Oct 2021 14:53:19 +0000 (08:53 -0600)]
block: remove some blk_mq_hw_ctx debugfs entries
Just like the blk_mq_ctx counterparts, we've got a bunch of counters
in here that are only for debugfs and are of questionnable value. They
are:
- dispatched, index of how many requests were dispatched in one go
- poll_{considered,invoked,success}, which track poll sucess rates. We're
confident in the iopoll implementation at this point, don't bother
tracking these.
As a bonus, this shrinks each hardware queue from 576 bytes to 512 bytes,
dropping a whole cacheline.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
These were added as part of early days debugging for blk-mq, and they
are not really useful anymore. Rather than spend cycles updating them,
just get rid of them.
As a bonus, this shrinks the per-cpu software queue size from 256b
to 192b. That's a whole cacheline less.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pavel Begunkov [Mon, 18 Oct 2021 20:37:27 +0000 (21:37 +0100)]
block: skip elevator fields init for non-elv queue
Don't init rq->hash and rq->rb_node in blk_mq_rq_ctx_init() if there is
no elevator. Also, move some other initialisers that imply barriers to
the end, so the compiler is free to rearrange and optimise other the
rest of them.
note: fold in a change from Jens leaving queue_list unconditional, as
it might lead to problems otherwise.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Fri, 15 Oct 2021 15:44:38 +0000 (09:44 -0600)]
block: store elevator state in request
Add an rq private RQF_ELV flag, which tells the block layer that this
request was initialized on a queue that has an IO scheduler attached.
This allows for faster checking in the fast path, rather than having to
deference rq->q later on.
Elevator switching does full quiesce of the queue before detaching an
IO scheduler, so it's safe to cache this in the request itself.
Jens Axboe [Sat, 16 Oct 2021 02:06:18 +0000 (20:06 -0600)]
block: only mark bio as tracked if it really is tracked
We set BIO_TRACKED unconditionally when rq_qos_throttle() is called, even
though we may not even have an rq_qos handler. Only mark it as TRACKED if
it really is potentially tracked.
This saves considerable time for the case where the bio isn't tracked:
2.64% -1.65% [kernel.vmlinux] [k] bio_endio
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Fri, 15 Oct 2021 21:03:52 +0000 (15:03 -0600)]
block: improve layout of struct request
It's been a while since this was analyzed, move some members around to
better flow with the use case. Initial state up top, and queued state
after that. This improves my peak case by about 1.5%, from 7750K to
7900K IOPS.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Thu, 14 Oct 2021 15:17:01 +0000 (09:17 -0600)]
block: move update request helpers into blk-mq.c
For some reason we still have them in blk-core, with the rest of the
request completion being in blk-mq. That causes and out-of-line call
for each completion.
Move them into blk-mq.c instead, where they belong.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Jens Axboe [Wed, 13 Oct 2021 15:01:43 +0000 (09:01 -0600)]
block: don't bother iter advancing a fully done bio
If we're completing nbytes and nbytes is the size of the bio, don't bother
with calling into the iterator increment helpers. Just clear the bio
size and we're done.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pavel Begunkov [Thu, 14 Oct 2021 14:03:26 +0000 (15:03 +0100)]
block: cache request queue in bdev
There are tons of places where we need to get a request_queue only
having bdev, which turns into bdev->bd_disk->queue. There are probably a
hundred of such places considering inline helpers, and enough of them
are in hot paths.
Cache queue pointer in struct block_device and make use of it in
bdev_get_queue().
Jens Axboe [Thu, 14 Oct 2021 17:17:43 +0000 (11:17 -0600)]
block: use flags instead of bit fields for blkdev_dio
This generates a lot better code for me, and bumps performance from
7650K IOPS to 7750K IOPS. Looking at profiles for the run and running
perf diff, it confirms that we're now sending a lot less time there:
Pavel Begunkov [Wed, 13 Oct 2021 08:57:11 +0000 (09:57 +0100)]
block: cache bdev in struct file for raw bdev IO
bdev = &BDEV_I(file->f_mapping->host)->bdev
Getting struct block_device from a file requires 2 memory dereferences
as illustrated above, that takes a toll on performance, so cache it in
yet unused file->private_data. That gives a noticeable peak performance
improvement.
Christoph Hellwig [Tue, 12 Oct 2021 11:12:25 +0000 (13:12 +0200)]
block: don't allow writing to the poll queue attribute
The poll attribute is a historic artefact from before when we had
explicit poll queues that require driver specific configuration.
Just print a warning when writing to the attribute.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Link: https://lore.kernel.org/r/20211012111226.760968-16-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Christoph Hellwig [Tue, 12 Oct 2021 11:12:24 +0000 (13:12 +0200)]
block: switch polling to be bio based
Replace the blk_poll interface that requires the caller to keep a queue
and cookie from the submissions with polling based on the bio.
Polling for the bio itself leads to a few advantages:
- the cookie construction can made entirely private in blk-mq.c
- the caller does not need to remember the request_queue and cookie
separately and thus sidesteps their lifetime issues
- keeping the device and the cookie inside the bio allows to trivially
support polling BIOs remapping by stacking drivers
- a lot of code to propagate the cookie back up the submission path can
be removed entirely.
Ming Lei [Tue, 12 Oct 2021 11:12:23 +0000 (13:12 +0200)]
block: define 'struct bvec_iter' as packed
'struct bvec_iter' is embedded into 'struct bio', define it as packed
so that we can get one extra 4bytes for other uses without expanding
bio.
'struct bvec_iter' is often allocated on stack, so making it packed
doesn't affect performance. Also I have run io_uring on both
nvme/null_blk, and not observe performance effect in this way.
Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Link: https://lore.kernel.org/r/20211012111226.760968-14-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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