Commit Graph

561006 Commits

Author SHA1 Message Date
Christoph Hellwig
e7a2a87d59 nvme: switch abort to blk_execute_rq_nowait
And remove the now unused nvme_submit_cmd helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:34 -07:00
Christoph Hellwig
d8f32166a9 nvme: switch delete SQ/CQ to blk_execute_rq_nowait
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:34 -07:00
Christoph Hellwig
7688faa6dd nvme: factor out a few helpers from req_completion
We'll need them in other places later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:34 -07:00
Christoph Hellwig
4680072003 nvme: fix admin queue depth
The number in tag_set->queue depth includes the reserved tags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:34 -07:00
Keith Busch
4b9d5b1510 NVMe: Simplify metadata setup
We no longer require the two-pass setup for block integrity.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:34 -07:00
Keith Busch
53029b0441 NVMe: Remove device management handles on remove
We don't want to allow new references to open on a device that is
removed. This ties the lifetime of these handles to the physical device's
presence rather than to the open reference count.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Keith Busch
92f7a1624b NVMe: Use unbounded work queue for all work
Removes all usage of the global work queue so work can't be
scheduled on two different work queues, and removes nvme's work queue
singlethreadedness so controllers can be driven in parallel.

Signed-off-by: Keith Busch <keith.busch@intel.com>
[hch: keep the dead controller removal on the system workqueue to avoid
 deadlocks]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Keith Busch
540c801c65 NVMe: Implement namespace list scanning
The NVMe 1.1 specification provides an identify mode to return a
list of active namespaces. This is more efficient to discover which
namespace identifiers are active on a controller, providing potentially
significant improvement in scan time for controllers with sparesly
populated namespaces.

Signed-off-by: Keith Busch <keith.busch@intel.com>
[hch: add quirk for the broken Qemu Identify implementation.  To be relaxed
 later]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
6bf25d1641 nvme: switch abort_limit to an atomic_t
There is no lock to sychronize access to the abort_limit field of
struct nvme_ctrl, so switch it to an atomic_t.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
5c8809e650 nvme: remove dead controllers from a work item
Compared to the kthread this gives us multiple call prevention for free.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
fd634f4142 nvme: merge probe_work and reset_work
If we're using two work queues we're always going to run into races where
one item is tearing down what the other one is initializing.  So insted
merge the two work queues, and let the old probe_work also tear the
controller down first if it was alive.  Together with the better detection
of the probe path using a flag this gives us a properly serialized
reset/probe path that also doesn't accidentally trigger when two commands
time out and the second one tries to reset the controller while the first
reset is still in progress.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Keith Busch
e1569a1618 nvme: do not restart the request timeout if we're resetting the controller
Otherwise we're never going to complete a command when it is restarted just
after we completed all other outstanding commands in nvme_clear_queue.

The controller must be disabled prior to completing a presumed lost
command, do this by directly shutting down the controller before
queueing the reset work, and return EH_HANDLED from the timeout handler
after we shut the controller down.

Signed-off-by: Keith Busch <keith.busch@intel.com>
[hch: split and rebase]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
846cc05f95 nvme: simplify resets
Don't delete the controller from dev_list before queuing a reset, instead
just check for it being reset in the polling kthread.  This allows to remove
the dev_list_lock in various places, and in addition we can simply rely on
checking the queue_work return value to see if we could reset a controller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
297465c873 nvme: add NVME_SC_CANCELLED
To properly document how we are using a negative Linux error value to
communicate request cancellations inside the driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
31c7c7d2c9 nvme: merge nvme_abort_req and nvme_timeout
We want to be able to return bettern error values frmo nvme_timeout, which
is significantly easier if the two functions are merged.  Also clean up and
reduce the printk spew so that we only get one message per abort.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:33 -07:00
Christoph Hellwig
4c9f748f0e nvme: don't take the I/O queue q_lock in nvme_timeout
There is nothing it protects, but it makes lockdep unhappy in many different
ways.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:32 -07:00
Keith Busch
77bf25ea70 nvme: protect against simultaneous shutdown invocations
Signed-off-by: Keith Busch <keith.busch@intel.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:32 -07:00
Christoph Hellwig
7385014c07 nvme: only add a controller to dev_list after it's been fully initialized
Without this we can easily get bad derferences on nvmeq->d_db when the nvme
kthread tries to poll the CQs for controllers that are in half initialized
state.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:23 -07:00
Christoph Hellwig
749941f236 nvme: only ignore hardware errors in nvme_create_io_queues
Half initialized queues due to kernel error returns or timeout are still a
good reason to give up on initializing a controller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:20 -07:00
Christoph Hellwig
287922eb0b block: defer timeouts to a workqueue
Timer context is not very useful for drivers to perform any meaningful abort
action from.  So instead of calling the driver from this useless context
defer it to a workqueue as soon as possible.

Note that while a delayed_work item would seem the right thing here I didn't
dare to use it due to the magic in blk_add_timer that pokes deep into timer
internals.  But maybe this encourages Tejun to add a sensible API for that to
the workqueue API and we'll all be fine in the end :)

Contains a major update from Keith Bush:

"This patch removes synchronizing the timeout work so that the timer can
 start a freeze on its own queue. The timer enters the queue, so timer
 context can only start a freeze, but not wait for frozen."

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-22 09:38:16 -07:00
Dan Carpenter
8c0b391550 nvme: precedence bug in nvme_pr_clear()
The "|" operator has higher precedence than "?:" so this didn't work as
intended.  I had previously fixed this bug, but it we copied the older
unfixed version when we moved the function between files.

Fixes: 1673f1f08c ('nvme: move block_device_operations and ns/ctrl freeing to common code')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-09 10:56:52 -07:00
Dan Carpenter
7b6c0f8034 blk-integrity: checking for NULL instead of IS_ERR
We recently changed bio_integrity_alloc() to return ERR_PTRs instead of
NULL but these calls were missed.

Fixes: 06c1e3902a ('blk-integrity: empty implementation when disabled')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-09 08:04:29 -07:00
Arnd Bergmann
d1ea7be5f7 nvme: fix another 32-bit build warning
The nvme_user_cmd function was recently moved around from one file
to another, which made a warning reappear that I had fixed before
at some point:

drivers/nvme/host/core.c: In function 'nvme_user_cmd':
drivers/nvme/host/core.c:424:4: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

This applies the same workaround that we have elsewhere in the
driver with an extra type cast to uintptr_t.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 1673f1f08c ("nvme: move block_device_operations and ns/ctrl freeing to common code")
Link: https://lkml.org/lkml/2015/10/9/611
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-08 12:14:25 -07:00
Christoph Hellwig
ac02dddec6 NVMe: fix build with CONFIG_NVM enabled
Looks like I didn't test with CONFIG_NVM enabled, and neither did
the build bot.

Most of this is really weird crazy shit in the lighnvm support, though.

Struct nvme_ns is a structure for the NVM I/O command set, and it has
no business poking into it.  Second this commit:

commit 47b3115ae7
Author: Wenwei Tao <ww.tao0320@gmail.com>
Date:   Fri Nov 20 13:47:55 2015 +0100

    nvme: lightnvm: use admin queues for admin cmds

Does even more crazy stuff.  If a function gets a request_queue parameter
passed it'd better use that and not look for another one.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-03 09:52:05 -07:00
Keith Busch
06c1e3902a blk-integrity: empty implementation when disabled
This patch moves the blk_integrity_payload definition outside the
CONFIG_BLK_DEV_INTERITY dependency and provides empty function
implementations when the kernel configuration disables integrity
extensions. This simplifies drivers that make use of these to map user
data so they don't need to repeat the same configuration checks.

Signed-off-by: Keith Busch <keith.busch@intel.com>

Updated by Jens to pass an error pointer return from
bio_integrity_alloc(), otherwise if CONFIG_BLK_DEV_INTEGRITY isn't
set, we return a weird ENOMEM from __nvme_submit_user_cmd()
if a meta buffer is set.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-03 09:32:21 -07:00
Christoph Hellwig
9a0be7abb6 nvme: refactor set_queue_count
Split out a helper that just issues the Set Features and interprets the
result which can go to common code, and document why we are ignoring
non-timeout error returns in the PCIe driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:40 -07:00
Christoph Hellwig
f3ca80fc11 nvme: move chardev and sysfs interface to common code
For this we need to add a proper controller init routine and a list of
all controllers that is in addition to the list of PCIe controllers,
which stays in pci.c.  Note that we remove the sysfs device when the
last reference to a controller is dropped now - the old code would have
kept it around longer, which doesn't make much sense.

This requires a new ->reset_ctrl operation to implement controleller
resets, and a new ->write_reg32 operation that is required to implement
subsystem resets.  We also now store caches copied of the NVMe compliance
version and the flag if a controller is attached to a subsystem or not in
the generic controller structure now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[Fixes for pr merge]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:40 -07:00
Christoph Hellwig
5bae7f73d3 nvme: move namespace scanning to common code
The namespace scanning code has been mostly generic already, we just
need to store a pointer to the tagset in the nvme_ctrl structure, and
add a method to check if a controller is I/O incapable.  The latter
will hopefully be replaced by a proper controller state machine soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[Fixed pr conflicts]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:40 -07:00
Christoph Hellwig
ce4541f40a nvme: move the call to nvme_init_identify earlier
We want to record the identify and CAP values even if no I/O queue
is available.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:40 -07:00
Christoph Hellwig
7fd8930f26 nvme: add a common helper to read Identify Controller data
And add the 64-bit register read operation for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
5fd4ce1b00 nvme: move nvme_{enable,disable,shutdown}_ctrl to common code
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
1b2eb37465 nvme: move remaining CC setup into nvme_enable_ctrl
Remove the calculation of all the bits written into the CC register into
nvme_enable_ctrl, so that they can be moved into the core NVMe driver in
the future.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
106198edb7 nvme: add explicit quirk handling
Add an enum for all workarounds not in the spec and identify the affected
controllers at probe time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
1673f1f08c nvme: move block_device_operations and ns/ctrl freeing to common code
This moves the block_device_operations over to common code mostly
as-is.  The only change is that the ns and ctrl refcounting got some
small refcounting to have wrappers around the kref_put operations.

A new free_ctrl operation is added to allow the PCI driver to free
it's ressources on the final drop.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[Moved the integrity and pr changes due to merge conflict]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Keith Busch
0b7f1f26f9 nvme: use the block layer for userspace passthrough metadata
Use the integrity API to pass through metadata from userspace.  For PI
enabled devices this means that we now validate the reftag, which seems
like an unintentional ommission in the old code.

Thanks to Keith Busch for testing and fixes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[Skip metadata setup on admin commands]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
4160982e75 nvme: split __nvme_submit_sync_cmd
Add a separate nvme_submit_user_cmd for commands that directly DMA
to or from userspace.  We'll add metadata support to that soon and
the common version would become too messy.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
22944e9981 nvme: move nvme_setup_flush and nvme_setup_rw to common code
And mark them inline so that we don't slow down the I/O submission path by
having to turn it into a forced out of line call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
15a190f7f5 nvme: move nvme_error_status to common code
And mark it inline so that we don't slow down the completion path by
having to turn it into a forced out of line call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
d4f6c3aba5 nvme: factor out a nvme_unmap_data helper
This is the counter part to nvme_map_data.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
ba1ca37ea4 nvme: refactor nvme_queue_rq
This "backports" the structure I've used for the fabrics driver.  It
mostly started out as a cleanup so that I could actually understand
the code, but I think it also qualifies as a micro-optimization due
to the reduced time we hold q_lock and disable interrupts.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
69d2b57174 nvme: simplify nvme_setup_prps calling convention
Pass back a true/false value instead of the length which needs a compare
with the bytes in the request and drop the pointless gfp_t argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:39 -07:00
Christoph Hellwig
1c63dc6658 nvme: split a new struct nvme_ctrl out of struct nvme_dev
The new struct nvme_ctrl will be used by the common NVMe code that sits
on top of struct request_queue and the new nvme_ctrl_ops abstraction.
It only contains the bare minimum required, which consists of values
sampled during controller probe, the admin queue pointer and a second
struct device pointer at the moment, but more will follow later.  Only
values that are not used in the I/O fast path should be moved to
struct nvme_ctrl so that drivers can optimize their cache line usage
easily.  That's also the reason why we have two device pointers as
the struct device is used for DMA mapping purposes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
01fec28a6f nvme: use vendor it from identify
Use the vendor ID from the identify data instead of the PCI device to
make the SCSI translation layer independent from the PCI driver.  The NVMe
spec defines them as having the same value for current PCIe devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
bf7d3ebbd2 nvme: split nvme_trans_device_id_page
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
7a67cbea65 nvme: use offset instead of a struct for registers
This makes life easier for future non-PCI drivers where access to the
registers might be more complicated.  Note that Linux drivers are
pretty evenly split between the two versions, and in fact the NVMe
driver already uses offsets for the doorbells.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
[Fixed CMBSZ offset]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
21d34711e1 nvme: split command submission helpers out of pci.c
Create a new core.c and start by adding the command submission helpers
to it, which are already abstracted away from the actual hardware queues
by the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
71bd150c71 nvme: move struct nvme_iod to pci.c
This structure is specific to the PCIe driver internals and should be moved
to pci.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:59:38 -07:00
Christoph Hellwig
6f3b0e8bcf blk-mq: add a flags parameter to blk_mq_alloc_request
We already have the reserved flag, and a nowait flag awkwardly encoded as
a gfp_t.  Add a real flags argument to make the scheme more extensible and
allow for a nicer calling convention.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01 10:53:59 -07:00
Jens Axboe
d7cf931dd9 Revert "blk-flush: Queue through IO scheduler when flush not required"
This reverts commit 1b2ff19e6a.

Jan writes:

--

Thanks for report! After some investigation I found out we allocate
elevator specific data in __get_request() only for non-flush requests. And
this is actually required since the flush machinery uses the space in
struct request for something else. Doh. So my patch is just wrong and not
easy to fix since at the time __get_request() is called we are not sure
whether the flush machinery will be used in the end. Jens, please revert
1b2ff19e6a. Thanks!

I'm somewhat surprised that you can reliably hit the race where flushing
gets disabled for the device just while the request is in flight. But I
guess during boot it makes some sense.

--

So let's just revert it, we can fix the queue run manually after the
fact. This race is rare enough that it didn't trigger in testing, it
requires the specific disable-while-in-flight scenario to trigger.
2015-11-25 11:02:02 -07:00
Jens Axboe
3b627a3f93 block: clarify blk_add_timer() use case for blk-mq
Just a comment update on not needing queue_lock, and that we aren't
really adding the request to a timeout list for !mq.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-11-24 15:58:53 -07:00