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The variable 'disk_type' is never modified so constify it.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Document the locking assumptions in functions that modify
blk_mq_ctx.rq_list to make it easier for humans to verify
this code.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Some functions in block/blk-core.c must only be used on blk-sq queues
while others are safe to use against any queue type. Document which
functions are intended for blk-sq queues and issue a warning if the
blk-sq API is misused. This does not only help block driver authors
but will also make it easier to remove the blk-sq code once that code
is declared obsolete.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of documenting the locking assumptions of most block layer
functions as a comment, use lockdep_assert_held() to verify locking
assumptions at runtime.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Initialization of blk-mq requests is a bit weird: blk_mq_rq_ctx_init()
is called after a value has been assigned to .rq_flags and .rq_flags
is initialized in __blk_mq_finish_request(). Initialize .rq_flags in
blk_mq_rq_ctx_init() instead of relying on __blk_mq_finish_request().
Moving the initialization of .rq_flags is fine because all changes
and tests of .rq_flags occur between blk_get_request() and finishing
a request.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Since scsi_req_init() works on a struct scsi_request, change the
argument type into struct scsi_request *.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of explicitly calling scsi_req_init() after blk_get_request(),
call that function from inside blk_get_request(). Add an
.initialize_rq_fn() callback function to the block drivers that need
it. Merge the IDE .init_rq_fn() function into .initialize_rq_fn()
because it is too small to keep it as a separate function. Keep the
scsi_req_init() call in ide_prep_sense() because it follows a
blk_rq_init() call.
References: commit 82ed4db499b8 ("block: split scsi_request out of struct request")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Several block drivers need to initialize the driver-private request
data after having called blk_get_request() and before .prep_rq_fn()
is called, e.g. when submitting a REQ_OP_SCSI_* request. Avoid that
that initialization code has to be repeated after every
blk_get_request() call by adding new callback functions to struct
request_queue and to struct blk_mq_ops.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Instead of declaring the second argument of blk_*_get_request()
as int and passing it to functions that expect an unsigned int,
declare that second argument as unsigned int. Also because of
consistency, rename that second argument from 'rw' into 'op'.
This patch does not change any functionality.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Since the srcu structure is rather large (184 bytes on an x86-64
system with kernel debugging disabled), only allocate it if needed.
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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A new bio operation flag REQ_NOWAIT is introduced to identify bio's
orignating from iocb with IOCB_NOWAIT. This flag indicates
to return immediately if a request cannot be made instead
of retrying.
Stacked devices such as md (the ones with make_request_fn hooks)
currently are not supported because it may block for housekeeping.
For example, an md can have a part of the device suspended.
For this reason, only request based devices are supported.
In the future, this feature will be expanded to stacked devices
by teaching them how to handle the REQ_NOWAIT flags.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This patch reverts commit 2719aa217e0d02(blk-mq: don't use
sync workqueue flushing from drivers) because only
blk_mq_quiesce_queue() need the sync flush, and now
we don't need to stop queue any more, so revert it.
Also changes to cancel_delayed_work() in blk_mq_stop_hw_queue().
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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BLK_MQ_S_STOPPED may not be observed in other concurrent I/O paths,
we can't guarantee that dispatching won't happen after returning
from the APIs of stopping queue.
So clarify the fact and avoid potential misuse.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Queue can be started by other blk-mq APIs and can be used in
different cases, this limits uses of blk_mq_quiesce_queue()
if it is based on stopping queue, and make its usage very
difficult, especially users have to use the stop queue APIs
carefully for avoiding to break blk_mq_quiesce_queue().
We have applied the QUIESCED flag for draining and blocking
dispatch, so it isn't necessary to stop queue any more.
After stopping queue is removed, blk_mq_quiesce_queue() can
be used safely and easily, then users won't worry about queue
restarting during quiescing at all.
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Actually what we want to get from blk_mq_quiesce_queue()
isn't only to wait for completion of all ongoing .queue_rq().
In the typical context of canceling requests, we need to
make sure that the following is done in the dispatch path
before starting to cancel requests:
- failed dispatched request is finished
- busy dispatched request is requeued, and the STARTED
flag is cleared
So update comment to keep code, doc and our expection consistent.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It is required that no dispatch can happen any more once
blk_mq_quiesce_queue() returns, and we don't have such requirement
on APIs of stopping queue.
But blk_mq_quiesce_queue() still may not block/drain dispatch in the
the case of BLK_MQ_S_START_ON_RUN, so use the new introduced flag of
QUEUE_FLAG_QUIESCED and evaluate it inside RCU read-side critical
sections for fixing this issue.
Also blk_mq_quiesce_queue() is implemented via stopping queue, which
limits its uses, and easy to cause race, because any queue restart in
other paths may break blk_mq_quiesce_queue(). With the introduced
flag of QUEUE_FLAG_QUIESCED, we don't need to depend on stopping queue
for quiescing any more.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_mq_start_stopped_hw_queues() is used implictly
as counterpart of blk_mq_quiesce_queue() for unquiescing queue,
so we introduce blk_mq_unquiesce_queue() and make it
as counterpart of blk_mq_quiesce_queue() explicitly.
This function is for improving the current quiescing mechanism
in the following patches.
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_bio_segment_split() makes sure bios have no more than
BIO_MAX_PAGES entries in the bi_io_vec.
This was done because bio_clone_bioset() (when given a
mempool bioset) could not handle larger io_vecs.
No driver uses bio_clone_bioset() any more, they all
use bio_clone_fast() if anything, and bio_clone_fast()
doesn't clone the bi_io_vec.
The main user of of bio_clone_bioset() at this level
is bounce.c, and bouncing now happens before blk_bio_segment_split(),
so that is not of concern.
So remove the big helpful comment and the code.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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bio_clone() is no longer used.
Only bio_clone_bioset() or bio_clone_fast().
This is for the best, as bio_clone() used fs_bio_set,
and filesystems are unlikely to want to use bio_clone().
So remove bio_clone() and all references.
This includes a fix to some incorrect documentation.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Since commit 23688bf4f830 ("block: ensure to split after potentially
bouncing a bio") blk_queue_bounce() is called *before*
blk_queue_split().
This means that:
1/ the comments blk_queue_split() about bounce buffers are
irrelevant, and
2/ a very large bio (more than BIO_MAX_PAGES) will no longer be
split before it arrives at blk_queue_bounce(), leading to the
possibility that bio_clone_bioset() will fail and a NULL
will be dereferenced.
Separately, blk_queue_bounce() shouldn't use fs_bio_set as the bio
being copied could be from the same set, and this could lead to a
deadlock.
So:
- allocate 2 private biosets for blk_queue_bounce, one for
splitting enormous bios and one for cloning bios.
- add code to split a bio that exceeds BIO_MAX_PAGES.
- Fix up the comments in blk_queue_split()
Credit-to: Ming Lei <tom.leiming@gmail.com> (suggested using single bio_for_each_segment loop)
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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A rescuing bioset is only useful if there might be bios from
that same bioset on the bio_list_on_stack queue at a time
when bio_alloc_bioset() is called. This never applies to
q->bio_split.
Allocations from q->bio_split are only ever made from
blk_queue_split() which is only ever called early in each of
various make_request_fn()s. The original bio (call this A)
is then passed to generic_make_request() and is placed on
the bio_list_on_stack queue, and the bio that was allocated
from q->bio_split (B) is processed.
The processing of this may cause other bios to be passed to
generic_make_request() or may even cause the bio B itself to
be passed, possible after some prefix has been split off
(using some other bioset).
generic_make_request() now guarantees that all of these bios
(B and dependants) will be fully processed before the tail
of the original bio A gets handled. None of these early bios
can possible trigger an allocation from the original
q->bio_split as they are either too small to require
splitting or (more likely) are destined for a different queue.
The next time that the original q->bio_split might be used
by this thread is when A is processed again, as it might
still be too big to handle directly. By this time there
cannot be any other bios allocated from q->bio_split in the
generic_make_request() queue. So no rescuing will ever be
needed.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This patch converts bioset_create() to not create a workqueue by
default, so alloctions will never trigger punt_bios_to_rescuer(). It
also introduces a new flag BIOSET_NEED_RESCUER which tells
bioset_create() to preserve the old behavior.
All callers of bioset_create() that are inside block device drivers,
are given the BIOSET_NEED_RESCUER flag.
biosets used by filesystems or other top-level users do not
need rescuing as the bio can never be queued behind other
bios. This includes fs_bio_set, blkdev_dio_pool,
btrfs_bioset, xfs_ioend_bioset, and one allocated by
target_core_iblock.c.
biosets used by md/raid do not need rescuing as
their usage was recently audited and revised to never
risk deadlock.
It is hoped that most, if not all, of the remaining biosets
can end up being the non-rescued version.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Credit-to: Ming Lei <ming.lei@redhat.com> (minor fixes)
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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"flags" arguments are often seen as good API design as they allow
easy extensibility.
bioset_create_nobvec() is implemented internally as a variation in
flags passed to __bioset_create().
To support future extension, make the internal structure part of the
API.
i.e. add a 'flags' argument to bioset_create() and discard
bioset_create_nobvec().
Note that the bio_split allocations in drivers/md/raid* do not need
the bvec mempool - they should have used bioset_create_nobvec().
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_queue_split() is always called with the last arg being q->bio_split,
where 'q' is the first arg.
Also blk_queue_split() sometimes uses the passed-in 'bs' and sometimes uses
q->bio_split.
This is inconsistent and unnecessary. Remove the last arg and always use
q->bio_split inside blk_queue_split()
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Credit-to: Javier González <jg@lightnvm.io> (Noticed that lightnvm was missed)
Reviewed-by: Javier González <javier@cnexlabs.com>
Tested-by: Javier González <javier@cnexlabs.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move most code into blk_mq_rq_ctx_init, and the rest into
blk_mq_get_request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This patch makes sure we always allocate requests in the core blk-mq
code and use a common prepare_request method to initialize them for
both mq I/O schedulers. For Kyber and additional limit_depth method
is added that is called before allocating the request.
Also because none of the intializations can really fail the new method
does not return an error - instead the bfq finish method is hardened
to deal with the no-IOC case.
Last but not least this removes the abuse of RQF_QUEUE by the blk-mq
scheduling code as RQF_ELFPRIV is all that is needed now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_mq_sched_assign_ioc now only handles the assigned of the ioc if
the schedule needs it (bfq only at the moment). The caller to the
per-request initializer is moved out so that it can be merged with
a similar call for the kyber I/O scheduler.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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icq_to_bic is a container_of operation, so we need to check for NULL
before it. Also move the check outside the spinlock while we're at
it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge three functions only tail-called by blk_mq_free_request into
blk_mq_free_request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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No need to have two different callouts of bfq vs kyber.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Having these as separate helpers in a header really does not help
readability, or my chances to refactor this code sanely.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Having them out of line in blk-mq-sched.c just makes the code flow
unnecessarily complicated.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull NVMe changes for 4.13 from Christoph:
Highlights:
- UUID identifier support from Johannes
- Lots of cleanups from Sagi
- Host Memory Buffer support from me
And lots of cleanups and smaller fixes of course.
Note that the UUID identifier changes are based on top of the uuid tree.
I am the maintainer of that tree and will send it to Linus as soon as
4.12 is released as various other trees depend on it as well (and the
diffstat includes those changes unfortunately)
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This patch fixes two sparse warnings introduced by the "dedicated
error codes for the block layer V3" patch series. These changes
have not been tested.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Avoid that the following complaint is reported:
BUG: sleeping function called from invalid context at kernel/workqueue.c:2790
in_atomic(): 1, irqs_disabled(): 0, pid: 41, name: rcuop/3
1 lock held by rcuop/3/41:
#0: (rcu_callback){......}, at: [<ffffffff8111f9a2>] rcu_nocb_kthread+0x282/0x500
Call Trace:
dump_stack+0x86/0xcf
___might_sleep+0x174/0x260
__might_sleep+0x4a/0x80
flush_work+0x7e/0x2e0
__cancel_work_timer+0x143/0x1c0
cancel_work_sync+0x10/0x20
blk_throtl_exit+0x25/0x60
blkcg_exit_queue+0x35/0x40
blk_release_queue+0x42/0x130
kobject_put+0xa9/0x190
This happens since we invoke callbacks that need to block from the
queue release handler. Fix this by pushing the final release to
a workqueue.
Reported-by: Ross Zwisler <zwisler@gmail.com>
Fixes: commit b425e5049258 ("block: Avoid that blk_exit_rl() triggers a use-after-free")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Updated changelog
Signed-off-by: Jens Axboe <axboe@fb.com>
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Should be a blk_status_t type, not an integer.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We've already got a few conflicts and upcoming work depends on some of the
changes that have gone into mainline as regression fixes for this series.
Pull in 4.12-rc5 to resolve these conflicts and make it easier on down stream
trees to continue working on 4.13 changes.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Use the same values for use for request completion errors as the return
value from ->queue_rq. BLK_STS_RESOURCE is special cased to cause
a requeue, and all the others are completed as-is.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings. This patch
instead introduces a new blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning. Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.
For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.
blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
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In blk-cgroup, operations on blkg objects are protected with the
request_queue lock. This is no more the lock that protects
I/O-scheduler operations in blk-mq. In fact, the latter are now
protected with a finer-grained per-scheduler-instance lock. As a
consequence, although blkg lookups are also rcu-protected, blk-mq I/O
schedulers may see inconsistent data when they access blkg and
blkg-related objects. BFQ does access these objects, and does incur
this problem, in the following case.
The blkg_lookup performed in bfq_get_queue, being protected (only)
through rcu, may happen to return the address of a copy of the
original blkg. If this is the case, then the blkg_get performed in
bfq_get_queue, to pin down the blkg, is useless: it does not prevent
blk-cgroup code from destroying both the original blkg and all objects
directly or indirectly referred by the copy of the blkg. BFQ accesses
these objects, which typically causes a crash for NULL-pointer
dereference of memory-protection violation.
Some additional protection mechanism should be added to blk-cgroup to
address this issue. In the meantime, this commit provides a quick
temporary fix for BFQ: cache (when safe) blkg data that might
disappear right after a blkg_lookup.
In particular, this commit exploits the following facts to achieve its
goal without introducing further locks. Destroy operations on a blkg
invoke, as a first step, hooks of the scheduler associated with the
blkg. And these hooks are executed with bfqd->lock held for BFQ. As a
consequence, for any blkg associated with the request queue an
instance of BFQ is attached to, we are guaranteed that such a blkg is
not destroyed, and that all the pointers it contains are consistent,
while that instance is holding its bfqd->lock. A blkg_lookup performed
with bfqd->lock held then returns a fully consistent blkg, which
remains consistent until this lock is held. In more detail, this holds
even if the returned blkg is a copy of the original one.
Finally, also the object describing a group inside BFQ needs to be
protected from destruction on the blkg_free of the original blkg
(which invokes bfq_pd_free). This commit adds private refcounting for
this object, to let it disappear only after no bfq_queue refers to it
any longer.
This commit also removes or updates some stale comments on locking
issues related to blk-cgroup operations.
Reported-by: Tomas Konir <tomas.konir@gmail.com>
Reported-by: Lee Tibbert <lee.tibbert@gmail.com>
Reported-by: Marco Piazza <mpiazza@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Tomas Konir <tomas.konir@gmail.com>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Marco Piazza <mpiazza@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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hard disk IO latency varies a lot depending on spindle move. The latency
range could be from several microseconds to several milliseconds. It's
pretty hard to get the baseline latency used by io.low.
We will use a different stragety here. The idea is only using IO with
spindle move to determine if cgroup IO is in good state. For HD, if io
latency is small (< 1ms), we ignore the IO. Such IO is likely from
sequential IO, and is helpless to help determine if a cgroup's IO is
impacted by other cgroups. With this, we only account IO with big
latency. Then we can choose a hardcoded baseline latency for HD (4ms,
which is typical IO latency with seek). With all these settings, the
io.low latency works for both HD and SSD.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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I have encountered a NULL pointer dereference in
throtl_schedule_pending_timer:
[ 413.735396] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
[ 413.735535] IP: [<ffffffff812ebbbf>] throtl_schedule_pending_timer+0x3f/0x210
[ 413.735643] PGD 22c8cf067 PUD 22cb34067 PMD 0
[ 413.735713] Oops: 0000 [#1] SMP
......
This is caused by the following case:
blk_throtl_bio
throtl_schedule_next_dispatch <= sq is top level one without parent
throtl_schedule_pending_timer
sq_to_tg(sq)->td->throtl_slice <= sq_to_tg(sq) returns NULL
Fix it by using sq_to_td instead of sq_to_tg(sq)->td, which will always
return a valid td.
Fixes: 297e3d854784 ("blk-throttle: make throtl_slice tunable")
Signed-off-by: Joseph Qi <qijiang.qj@alibaba-inc.com>
Reviewed-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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If queue is stopped, we shouldn't dispatch request into driver and
hardware, unfortunately the check is removed in bd166ef183c2(blk-mq-sched:
add framework for MQ capable IO schedulers).
This patch fixes the issue by moving the check back into
__blk_mq_try_issue_directly().
This patch fixes request use-after-free[1][2] during canceling requets
of NVMe in nvme_dev_disable(), which can be triggered easily during
NVMe reset & remove test.
[1] oops kernel log when CONFIG_BLK_DEV_INTEGRITY is on
[ 103.412969] BUG: unable to handle kernel NULL pointer dereference at 000000000000000a
[ 103.412980] IP: bio_integrity_advance+0x48/0xf0
[ 103.412981] PGD 275a88067
[ 103.412981] P4D 275a88067
[ 103.412982] PUD 276c43067
[ 103.412983] PMD 0
[ 103.412984]
[ 103.412986] Oops: 0000 [#1] SMP
[ 103.412989] Modules linked in: vfat fat intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel crypto_simd cryptd ipmi_ssif iTCO_wdt iTCO_vendor_support mxm_wmi glue_helper dcdbas ipmi_si mei_me pcspkr mei sg ipmi_devintf lpc_ich ipmi_msghandler shpchp acpi_power_meter wmi nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm crc32c_intel nvme ahci nvme_core libahci libata tg3 i2c_core megaraid_sas ptp pps_core dm_mirror dm_region_hash dm_log dm_mod
[ 103.413035] CPU: 0 PID: 102 Comm: kworker/0:2 Not tainted 4.11.0+ #1
[ 103.413036] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.2.5 09/06/2016
[ 103.413041] Workqueue: events nvme_remove_dead_ctrl_work [nvme]
[ 103.413043] task: ffff9cc8775c8000 task.stack: ffffc033c252c000
[ 103.413045] RIP: 0010:bio_integrity_advance+0x48/0xf0
[ 103.413046] RSP: 0018:ffffc033c252fc10 EFLAGS: 00010202
[ 103.413048] RAX: 0000000000000000 RBX: ffff9cc8720a8cc0 RCX: ffff9cca72958240
[ 103.413049] RDX: ffff9cca72958000 RSI: 0000000000000008 RDI: ffff9cc872537f00
[ 103.413049] RBP: ffffc033c252fc28 R08: 0000000000000000 R09: ffffffffb963a0d5
[ 103.413050] R10: 000000000000063e R11: 0000000000000000 R12: ffff9cc8720a8d18
[ 103.413051] R13: 0000000000001000 R14: ffff9cc872682e00 R15: 00000000fffffffb
[ 103.413053] FS: 0000000000000000(0000) GS:ffff9cc877c00000(0000) knlGS:0000000000000000
[ 103.413054] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 103.413055] CR2: 000000000000000a CR3: 0000000276c41000 CR4: 00000000001406f0
[ 103.413056] Call Trace:
[ 103.413063] bio_advance+0x2a/0xe0
[ 103.413067] blk_update_request+0x76/0x330
[ 103.413072] blk_mq_end_request+0x1a/0x70
[ 103.413074] blk_mq_dispatch_rq_list+0x370/0x410
[ 103.413076] ? blk_mq_flush_busy_ctxs+0x94/0xe0
[ 103.413080] blk_mq_sched_dispatch_requests+0x173/0x1a0
[ 103.413083] __blk_mq_run_hw_queue+0x8e/0xa0
[ 103.413085] __blk_mq_delay_run_hw_queue+0x9d/0xa0
[ 103.413088] blk_mq_start_hw_queue+0x17/0x20
[ 103.413090] blk_mq_start_hw_queues+0x32/0x50
[ 103.413095] nvme_kill_queues+0x54/0x80 [nvme_core]
[ 103.413097] nvme_remove_dead_ctrl_work+0x1f/0x40 [nvme]
[ 103.413103] process_one_work+0x149/0x360
[ 103.413105] worker_thread+0x4d/0x3c0
[ 103.413109] kthread+0x109/0x140
[ 103.413111] ? rescuer_thread+0x380/0x380
[ 103.413113] ? kthread_park+0x60/0x60
[ 103.413120] ret_from_fork+0x2c/0x40
[ 103.413121] Code: 08 4c 8b 63 50 48 8b 80 80 00 00 00 48 8b 90 d0 03 00 00 31 c0 48 83 ba 40 02 00 00 00 48 8d 8a 40 02 00 00 48 0f 45 c1 c1 ee 09 <0f> b6 48 0a 0f b6 40 09 41 89 f5 83 e9 09 41 d3 ed 44 0f af e8
[ 103.413145] RIP: bio_integrity_advance+0x48/0xf0 RSP: ffffc033c252fc10
[ 103.413146] CR2: 000000000000000a
[ 103.413157] ---[ end trace cd6875d16eb5a11e ]---
[ 103.455368] Kernel panic - not syncing: Fatal exception
[ 103.459826] Kernel Offset: 0x37600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[ 103.850916] ---[ end Kernel panic - not syncing: Fatal exception
[ 103.857637] sched: Unexpected reschedule of offline CPU#1!
[ 103.863762] ------------[ cut here ]------------
[2] kernel hang in blk_mq_freeze_queue_wait() when CONFIG_BLK_DEV_INTEGRITY is off
[ 247.129825] INFO: task nvme-test:1772 blocked for more than 120 seconds.
[ 247.137311] Not tainted 4.12.0-rc2.upstream+ #4
[ 247.142954] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 247.151704] Call Trace:
[ 247.154445] __schedule+0x28a/0x880
[ 247.158341] schedule+0x36/0x80
[ 247.161850] blk_mq_freeze_queue_wait+0x4b/0xb0
[ 247.166913] ? remove_wait_queue+0x60/0x60
[ 247.171485] blk_freeze_queue+0x1a/0x20
[ 247.175770] blk_cleanup_queue+0x7f/0x140
[ 247.180252] nvme_ns_remove+0xa3/0xb0 [nvme_core]
[ 247.185503] nvme_remove_namespaces+0x32/0x50 [nvme_core]
[ 247.191532] nvme_uninit_ctrl+0x2d/0xa0 [nvme_core]
[ 247.196977] nvme_remove+0x70/0x110 [nvme]
[ 247.201545] pci_device_remove+0x39/0xc0
[ 247.205927] device_release_driver_internal+0x141/0x200
[ 247.211761] device_release_driver+0x12/0x20
[ 247.216531] pci_stop_bus_device+0x8c/0xa0
[ 247.221104] pci_stop_and_remove_bus_device_locked+0x1a/0x30
[ 247.227420] remove_store+0x7c/0x90
[ 247.231320] dev_attr_store+0x18/0x30
[ 247.235409] sysfs_kf_write+0x3a/0x50
[ 247.239497] kernfs_fop_write+0xff/0x180
[ 247.243867] __vfs_write+0x37/0x160
[ 247.247757] ? selinux_file_permission+0xe5/0x120
[ 247.253011] ? security_file_permission+0x3b/0xc0
[ 247.258260] vfs_write+0xb2/0x1b0
[ 247.261964] ? syscall_trace_enter+0x1d0/0x2b0
[ 247.266924] SyS_write+0x55/0xc0
[ 247.270540] do_syscall_64+0x67/0x150
[ 247.274636] entry_SYSCALL64_slow_path+0x25/0x25
[ 247.279794] RIP: 0033:0x7f5c96740840
[ 247.283785] RSP: 002b:00007ffd00e87ee8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 247.292238] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f5c96740840
[ 247.300194] RDX: 0000000000000002 RSI: 00007f5c97060000 RDI: 0000000000000001
[ 247.308159] RBP: 00007f5c97060000 R08: 000000000000000a R09: 00007f5c97059740
[ 247.316123] R10: 0000000000000001 R11: 0000000000000246 R12: 00007f5c96a14400
[ 247.324087] R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
[ 370.016340] INFO: task nvme-test:1772 blocked for more than 120 seconds.
Fixes: 12d70958a2e8(blk-mq: don't fail allocating driver tag for stopped hw queue)
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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When direct issue is done on request picked up from plug list,
the hctx need to be updated with the actual hw queue, otherwise
wrong hctx is used and may hurt performance, especially when
wrong SRCU readlock is acquired/released
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
Bart Van Assche
Goldwyn Rodrigues
Ingo Molnar
Ming Lei
NeilBrown
Christoph Hellwig
Jens Axboe
Jens Axboe
Paolo Valente
Shaohua Li
Joseph Qi