It is nontrivial to derive from the blk-mq source code when
blk_mq_tags.active_queues is decremented. Hence add a comment that
explains this.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
UFS partitions from newer versions of FreeBSD 10 and 11 use relative
addressing for their subpartitions. But older versions of FreeBSD still
use absolute addressing just like OpenBSD and NetBSD.
Instead of simply testing for a FreeBSD partition, the code needs to
also test if the starting offset of the C subpartition is zero.
https://bugzilla.kernel.org/show_bug.cgi?id=197733
Signed-off-by: Richard Narron <comet.berkeley@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit '7b9e93616399' ("blk-mq-sched: unify request finished methods")
changed the old name of current bfq_finish_request method, but left it
unchanged elsewhere in the code (related comments, part of function
name bfq_put_rq_priv_body).
This commit fixes all occurrences of the old name of this method by
changing them into the current name.
Fixes: 7b9e936163 ("blk-mq-sched: unify request finished methods")
Reviewed-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Federico Motta <federico@willer.it>
Signed-off-by: Chiara Bruschi <bruschi.chiara@outlook.it>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit a2d37968d7.
If max segment size isn't 512-aligned, this patch won't work well.
Also once multipage bvec is enabled, adjacent bvecs won't be physically
contiguous if page is added via bio_add_page(), so we don't need this
kind of complicated logic.
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's not available if we don't have group io scheduling set, and
there's no need to call it.
Fixes: 0d52af5905 ("block, bfq: release oom-queue ref to root group on exit")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 3a025e1d1c ("Add optional check for bad kernel-doc comments")
causes W=1 the kernel-doc script to be run and thereby causes several
new warnings to appear when building the kernel with W=1. Fix the
block layer kernel-doc headers such that the block layer again builds
cleanly with W=1.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Change "nedeing" into "needing" and "caes" into "cases".
Fixes: commit f906a6a0f4 ("blk-mq: improve tag waiting setup for non-shared tags")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In some stupider versions of gcc, it complains:
block/blk-mq.c: In function ‘blk_mq_complete_request’:
./include/linux/srcu.h:175:2: warning: ‘srcu_idx’ may be used uninitialized in this function [-Wmaybe-uninitialized]
__srcu_read_unlock(sp, idx);
^
block/blk-mq.c:620:6: note: ‘srcu_idx’ was declared here
int srcu_idx;
^
which is completely bogus, since we only use srcu_idx when
hctx->flags & BLK_MQ_F_BLOCKING is set, and that's the case where
hctx_lock() has initialized it.
Just set it to '0' in the normal path in hctx_lock() to silence
this annoying warning.
Fixes: 04ced159ce ("blk-mq: move hctx lock/unlock into a helper")
Fixes: 5197c05e16 ("blk-mq: protect completion path with RCU")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The RCU protection has been expanded to cover both queueing and
completion paths making ->queue_rq_srcu a misnomer. Rename it to
->srcu as suggested by Bart.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After the recent updates to use generation number and state based
synchronization, we can easily replace REQ_ATOM_STARTED usages by
adding an extra state to distinguish completed but not yet freed
state.
Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with
blk_mq_rq_state() tests. REQ_ATOM_STARTED no longer has any users
left and is removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After the recent updates to use generation number and state based
synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except
to avoid firing the same timeout multiple times.
Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag
RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple
times. This removes atomic bitops from hot paths too.
v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out().
v3: Added RQF_MQ_TIMEOUT_EXPIRED flag.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With issue/complete and timeout paths now using the generation number
and state based synchronization, blk_abort_request() is the only one
which depends on REQ_ATOM_COMPLETE for arbitrating completion.
There's no reason for blk_abort_request() to be a completely separate
path. This patch makes blk_abort_request() piggyback on the timeout
path instead of trying to terminate the request directly.
This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq.
Note that this makes blk_abort_request() asynchronous - it initiates
abortion but the actual termination will happen after a short while,
even when the caller owns the request. AFAICS, SCSI and ATA should be
fine with that and I think mtip32xx and dasd should be safe but not
completely sure. It'd be great if people who know the drivers take a
look.
v2: - Add comment explaining the lack of synchronization around
->deadline update as requested by Bart.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi SP <asamymuthupa@micron.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_mq_check_inflight() and blk_mq_poll_hybrid_sleep() test
REQ_ATOM_COMPLETE to determine the request state. Both uses are
speculative and we can test REQ_ATOM_STARTED and blk_mq_rq_state() for
equivalent results. Replace the tests. This will allow removing
REQ_ATOM_COMPLETE usages from blk-mq.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, blk-mq timeout path synchronizes against the usual
issue/completion path using a complex scheme involving atomic
bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence
rules. Unfortunately, it contains quite a few holes.
There's a complex dancing around REQ_ATOM_STARTED and
REQ_ATOM_COMPLETE between issue/completion and timeout paths; however,
they don't have a synchronization point across request recycle
instances and it isn't clear what the barriers add.
blk_mq_check_expired() can easily read STARTED from N-2'th iteration,
deadline from N-1'th, blk_mark_rq_complete() against Nth instance.
In fact, it's pretty easy to make blk_mq_check_expired() terminate a
later instance of a request. If we induce 5 sec delay before
time_after_eq() test in blk_mq_check_expired(), shorten the timeout to
2s, and issue back-to-back large IOs, blk-mq starts timing out
requests spuriously pretty quickly. Nothing actually timed out. It
just made the call on a recycle instance of a request and then
terminated a later instance long after the original instance finished.
The scenario isn't theoretical either.
This patch replaces the broken synchronization mechanism with a RCU
and generation number based one.
1. Each request has a u64 generation + state value, which can be
updated only by the request owner. Whenever a request becomes
in-flight, the generation number gets bumped up too. This provides
the basis for the timeout path to distinguish different recycle
instances of the request.
Also, marking a request in-flight and setting its deadline are
protected with a seqcount so that the timeout path can fetch both
values coherently.
2. The timeout path fetches the generation, state and deadline. If
the verdict is timeout, it records the generation into a dedicated
request abortion field and does RCU wait.
3. The completion path is also protected by RCU (from the previous
patch) and checks whether the current generation number and state
match the abortion field. If so, it skips completion.
4. The timeout path, after RCU wait, scans requests again and
terminates the ones whose generation and state still match the ones
requested for abortion.
By now, the timeout path knows that either the generation number
and state changed if it lost the race or the completion will yield
to it and can safely timeout the request.
While it's more lines of code, it's conceptually simpler, doesn't
depend on direct use of subtle memory ordering or coherence, and
hopefully doesn't terminate the wrong instance.
While this change makes REQ_ATOM_COMPLETE synchronization unnecessary
between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't
removed yet as it's still used in other places. Future patches will
move all state tracking to the new mechanism and remove all bitops in
the hot paths.
Note that this patch adds a comment explaining a race condition in
BLK_EH_RESET_TIMER path. The race has always been there and this
patch doesn't change it. It's just documenting the existing race.
v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao.
- s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter.
- READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter.
v3: - Fixed possible extended seqcount / u64_stats_sync read looping
spotted by Peter.
- MQ_RQ_IDLE was incorrectly being set in complete_request instead
of free_request. Fixed.
v4: - Rebased on top of hctx_lock() refactoring patch.
- Added comment explaining the use of hctx_lock() in completion path.
v5: - Added comments requested by Bart.
- Note the addition of BLK_EH_RESET_TIMER race condition in the
commit message.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, blk-mq protects only the issue path with RCU. This patch
puts the completion path under the same RCU protection. This will be
used to synchronize issue/completion against timeout by later patches,
which will also add the comments.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the RCU vs SRCU logic into lock/unlock helpers, which makes
the actual functional bits within the locked region much easier
to read.
tj: Reordered in front of timeout revamp patches and added the missing
blk_mq_run_hw_queue() conversion.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On scheduler init, a reference to the root group, and a reference to
its corresponding blkg are taken for the oom queue. Yet these
references are not released on scheduler exit, which prevents these
objects from be freed. This commit adds the missing reference
releases.
Reported-by: Davide Ferrari <davideferrari8@gmail.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For each pair [device for which bfq is selected as I/O scheduler,
group in blkio/io], bfq maintains a corresponding bfq group. Each such
bfq group contains a set of async queues, with each async queue
created on demand, i.e., when some I/O request arrives for it. On
creation, an async queue gets an extra reference, to make sure that
the queue is not freed as long as its bfq group exists. Accordingly,
to allow the queue to be freed after the group exited, this extra
reference must released on group exit.
The above holds also for a bfq root group, i.e., for the bfq group
corresponding to the root blkio/io root for a given device. Yet, by
mistake, the references to the existing async queues of a root group
are not released when the latter exits. This causes a memory leak when
the instance of bfq for a given device exits. In a similar vein,
bfqg_stats_xfer_dead is not executed for a root group.
This commit fixes bfq_pd_offline so that the latter executes the above
missing operations for a root group too.
Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reported-by: Guoqing Jiang <gqjiang@suse.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Davide Ferrari <davideferrari8@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In both elevator_switch_mq() and blk_mq_update_nr_hw_queues(), sched tags
can be allocated, and q->nr_hw_queue is used, and race is inevitable, for
example: blk_mq_init_sched() may trigger use-after-free on hctx, which is
freed in blk_mq_realloc_hw_ctxs() when nr_hw_queues is decreased.
This patch fixes the race be holding q->sysfs_lock.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Dispatch may still be in-progress after queue is frozen, so we have to
quiesce queue before switching IO scheduler and updating nr_requests.
Also when switching io schedulers, blk_mq_run_hw_queue() may still be
called somewhere(such as from nvme_reset_work()), and io scheduler's
per-hctx data may not be setup yet, so cause oops even inside
blk_mq_hctx_has_pending(), such as it can be run just between:
ret = e->ops.mq.init_sched(q, e);
AND
ret = e->ops.mq.init_hctx(hctx, i)
inside blk_mq_init_sched().
This reverts commit 7a148c2fcff8330(block: don't call blk_mq_quiesce_queue()
after queue is frozen) basically, and makes sure blk_mq_hctx_has_pending
won't be called if queue is quiesced.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixes: 7a148c2fcff83309(block: don't call blk_mq_quiesce_queue() after queue is frozen)
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't pass in the hardware queue to __dd_dispatch_request(), since it
leads the reader to believe that we are returning a request for that
specific hardware queue. That's not how mq-deadline works, the state
for determining which request to serve next is shared across all
hardware queues for a device.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In this case, 'sectors' can't be zero at all, so remove the check
and let the bio be split.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When merging one bvec into segment, if the bvec is too big
to merge, current policy is to move the whole bvec into another
new segment.
This patchset changes the policy into trying to maximize size of
front segments, that means in above situation, part of bvec
is merged into current segment, and the remainder is put
into next segment.
This patch prepares for support multipage bvec because
it can be quite common to see this case and we should try
to make front segments in full size.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is enough to check and compute bio->bi_seg_front_size just
after the 1st segment is found, but current code checks that
for each bvec, which is inefficient.
This patch follows the way in __blk_recalc_rq_segments()
for computing bio->bi_seg_front_size, and it is more efficient
and code becomes more readable too.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bcache is the only user of bio_alloc_pages(), so move this function into
bcache, and avoid it being misused in the future.
Also rename it to bch_bio_allo_pages() since it is bcache only.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Firstly this patch introduces BVEC_ITER_ALL_INIT for iterating one bio
from start to end.
As we need to support multipage bvecs, don't access bio->bi_io_vec
in copy_to_high_bio_irq(), and just use the standard iterator for that.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We will support multipage bvecs in the future, so change to iterator way
for getting bv_page of bvec from original bio.
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit a33801e8b4 ("block, bfq: move debug blkio stats behind
CONFIG_DEBUG_BLK_CGROUP") introduced two batches of confusing ifdefs:
one reported in [1], plus a similar one in another function. This
commit removes both batches, in the way suggested in [1].
[1] https://www.spinics.net/lists/linux-block/msg20043.html
Fixes: a33801e8b4 ("block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
BFQ privileges the I/O of soft real-time applications, such as video
players, to guarantee to these application a high bandwidth and a low
latency. In this respect, it is not easy to correctly detect when an
application is soft real-time. A particularly nasty false positive is
that of an I/O-bound application that occasionally happens to meet all
requirements to be deemed as soft real-time. After being detected as
soft real-time, such an application monopolizes the device. Fortunately,
BFQ will realize soon that the application is actually not soft
real-time and suspend every privilege. Yet, the application may happen
again to be wrongly detected as soft real-time, and so on.
As highlighted by our tests, this problem causes BFQ to occasionally
fail to guarantee a high responsiveness, in the presence of heavy
background I/O workloads. The reason is that the background workload
happens to be detected as soft real-time, more or less frequently,
during the execution of the interactive task under test. To give an
idea, because of this problem, Libreoffice Writer occasionally takes 8
seconds, instead of 3, to start up, if there are sequential reads and
writes in the background, on a Kingston SSDNow V300.
This commit addresses this issue by leveraging the following facts.
The reason why some applications are detected as soft real-time despite
all BFQ checks to avoid false positives, is simply that, during high
CPU or storage-device load, I/O-bound applications may happen to do
I/O slowly enough to meet all soft real-time requirements, and pass
all BFQ extra checks. Yet, this happens only for limited time periods:
slow-speed time intervals are usually interspersed between other time
intervals during which these applications do I/O at a very high speed.
To exploit these facts, this commit introduces a little change, in the
detection of soft real-time behavior, to systematically consider also
the recent past: the higher the speed was in the recent past, the
later next I/O should arrive for the application to be considered as
soft real-time. At the beginning of a slow-speed interval, the minimum
arrival time allowed for the next I/O usually happens to still be so
high, to fall *after* the end of the slow-speed period itself. As a
consequence, the application does not risk to be deemed as soft
real-time during the slow-speed interval. Then, during the next
high-speed interval, the application cannot, evidently, be deemed as
soft real-time (exactly because of its speed), and so on.
This extra filtering proved to be rather effective: in the above test,
the frequency of false positives became so low that the start-up time
was 3 seconds in all iterations (apart from occasional outliers,
caused by page-cache-management issues, which are out of the scope of
this commit, and cannot be solved by an I/O scheduler).
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When two or more processes do I/O in a way that the their requests are
sequential in respect to one another, BFQ merges the bfq_queues associated
with the processes. This way the overall I/O pattern becomes sequential,
and thus there is a boost in througput.
These cooperating processes usually start or restart to do I/O shortly
after each other. So, in order to avoid merging non-cooperating processes,
BFQ ensures that none of these queues has been in weight raising for too
long.
In this respect, from commit "block, bfq-sq, bfq-mq: let a queue be merged
only shortly after being created", BFQ checks whether any queue (and not
only weight-raised ones) is doing I/O continuously from too long to be
merged.
This new additional check makes the first one useless: a queue doing
I/O from long enough, if being weight-raised, is also a queue in
weight raising for too long to be merged. Accordingly, this commit
removes the first check.
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In BFQ and CFQ, two processes are said to be cooperating if they do
I/O in such a way that the union of their I/O requests yields a
sequential I/O pattern. To get such a sequential I/O pattern out of
the non-sequential pattern of each cooperating process, BFQ and CFQ
merge the queues associated with these processes. In more detail,
cooperating processes, and thus their associated queues, usually
start, or restart, to do I/O shortly after each other. This is the
case, e.g., for the I/O threads of KVM/QEMU and of the dump
utility. Basing on this assumption, this commit allows a bfq_queue to
be merged only during a short time interval (100ms) after it starts,
or re-starts, to do I/O. This filtering provides two important
benefits.
First, it greatly reduces the probability that two non-cooperating
processes have their queues merged by mistake, if they just happen to
do I/O close to each other for a short time interval. These spurious
merges cause loss of service guarantees. A low-weight bfq_queue may
unjustly get more than its expected share of the throughput: if such a
low-weight queue is merged with a high-weight queue, then the I/O for
the low-weight queue is served as if the queue had a high weight. This
may damage other high-weight queues unexpectedly. For instance,
because of this issue, lxterminal occasionally took 7.5 seconds to
start, instead of 6.5 seconds, when some sequential readers and
writers did I/O in the background on a FUJITSU MHX2300BT HDD. The
reason is that the bfq_queues associated with some of the readers or
the writers were merged with the high-weight queues of some processes
that had to do some urgent but little I/O. The readers then exploited
the inherited high weight for all or most of their I/O, during the
start-up of terminal. The filtering introduced by this commit
eliminated any outlier caused by spurious queue merges in our start-up
time tests.
This filtering also provides a little boost of the throughput
sustainable by BFQ: 3-4%, depending on the CPU. The reason is that,
once a bfq_queue cannot be merged any longer, this commit makes BFQ
stop updating the data needed to handle merging for the queue.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A just-created bfq_queue will certainly be deemed as interactive on
the arrival of its first I/O request, if the low_latency flag is
set. Yet, if the queue is merged with another queue on the arrival of
its first I/O request, it will not have the chance to be flagged as
interactive. Nevertheless, if the queue is then split soon enough, it
has to be flagged as interactive after the split.
To handle this early-merge scenario correctly, BFQ saves the state of
the queue, on the merge, as if the latter had already been deemed
interactive. So, if the queue is split soon, it will get
weight-raised, because the previous state of the queue is resumed on
the split.
Unfortunately, in the act of saving the state of the newly-created
queue, BFQ doesn't check whether the low_latency flag is set, and this
causes early-merged queues to be then weight-raised, on queue splits,
even if low_latency is off. This commit addresses this problem by
adding the missing check.
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If two processes do I/O close to each other, then BFQ merges the
bfq_queues associated with these processes, to get a more sequential
I/O, and thus a higher throughput. In this respect, to detect whether
two processes are doing I/O close to each other, BFQ keeps a list of
the head-of-line I/O requests of all active bfq_queues. The list is
ordered by initial sectors, and implemented through a red-black tree
(rq_pos_tree).
Unfortunately, the update of the rq_pos_tree was incomplete, because
the tree was not updated on the removal of the head-of-line I/O
request of a bfq_queue, in case the queue did not remain empty. This
commit adds the missing update.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If two processes do I/O close to each other, i.e., are cooperating
processes in BFQ (and CFQ'S) nomenclature, then BFQ merges their
associated bfq_queues, so as to get sequential I/O from the union of
the I/O requests of the processes, and thus reach a higher
throughput. A merged queue is then split if its I/O stops being
sequential. In this respect, BFQ deems the I/O of a bfq_queue as
(mostly) sequential only if less than 4 I/O requests are random, out
of the last 32 requests inserted into the queue.
Unfortunately, extensive testing (with the interleaved_io benchmark of
the S suite [1], and with real applications spawning cooperating
processes) has clearly shown that, with such a low threshold, only a
rather low I/O throughput may be reached when several cooperating
processes do I/O. In particular, the outcome of each test run was
bimodal: if queue merging occurred and was stable during the test,
then the throughput was close to the peak rate of the storage device,
otherwise the throughput was arbitrarily low (usually around 1/10 of
the peak rate with a rotational device). The probability to get the
unlucky outcomes grew with the number of cooperating processes: it was
already significant with 5 processes, and close to one with 7 or more
processes.
The cause of the low throughput in the unlucky runs was that the
merged queues containing the I/O of these cooperating processes were
soon split, because they contained more random I/O requests than those
tolerated by the 4/32 threshold, but
- that I/O would have however allowed the storage device to reach
peak throughput or almost peak throughput;
- in contrast, the I/O of these processes, if served individually
(from separate queues) yielded a rather low throughput.
So we repeated our tests with increasing values of the threshold,
until we found the minimum value (19) for which we obtained maximum
throughput, reliably, with at least up to 9 cooperating
processes. Then we checked that the use of that higher threshold value
did not cause any regression for any other benchmark in the suite [1].
This commit raises the threshold to such a higher value.
[1] https://github.com/Algodev-github/S
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce zone write locking to avoid write request reordering with
zoned block devices. This is achieved using a finer selection of the
next request to dispatch:
1) Any non-write request is always allowed to proceed.
2) Any write to a conventional zone is always allowed to proceed.
3) For a write to a sequential zone, the zone lock is first checked.
a) If the zone is not locked, the write is allowed to proceed after
its target zone is locked.
b) If the zone is locked, the write request is skipped and the next
request in the dispatch queue tested (back to step 1).
For a write request that has locked its target zone, the zone is
unlocked either when the request completes and the method
deadline_request_completed() is called, or when the request is requeued
using the method deadline_add_request().
Requests targeting a locked zone are always left in the scheduler queue
to preserve the initial write order. If no write request can be
dispatched, allow reads to be dispatched even if the write batch is not
done.
If the device used is not a zoned block device, or if zoned block device
support is disabled, this patch does not modify deadline behavior.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Avoid directly referencing the next_rq and fifo_list arrays using the
helper functions deadline_next_request() and deadline_fifo_request() to
facilitate changes in the dispatch request selection in
deadline_dispatch_requests() for zoned block devices.
While at it, also remove the unnecessary forward declaration of the
function deadline_move_request().
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce zone write locking to avoid write request reordering with
zoned block devices. This is achieved using a finer selection of the
next request to dispatch:
1) Any non-write request is always allowed to proceed.
2) Any write to a conventional zone is always allowed to proceed.
3) For a write to a sequential zone, the zone lock is first checked.
a) If the zone is not locked, the write is allowed to proceed after
its target zone is locked.
b) If the zone is locked, the write request is skipped and the next
request in the dispatch queue tested (back to step 1).
For a write request that has locked its target zone, the zone is
unlocked either when the request completes with a call to the method
deadline_request_completed() or when the request is requeued using
dd_insert_request().
Requests targeting a locked zone are always left in the scheduler queue
to preserve the lba ordering for write requests. If no write request
can be dispatched, allow reads to be dispatched even if the write batch
is not done.
If the device used is not a zoned block device, or if zoned block device
support is disabled, this patch does not modify mq-deadline behavior.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Avoid directly referencing the next_rq and fifo_list arrays using the
helper functions deadline_next_request() and deadline_fifo_request() to
facilitate changes in the dispatch request selection in
__dd_dispatch_request() for zoned block devices.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Components relying only on the request_queue structure for accessing
block devices (e.g. I/O schedulers) have a limited knowledged of the
device characteristics. In particular, the device capacity cannot be
easily discovered, which for a zoned block device also result in the
inability to easily know the number of zones of the device (the zone
size is indicated by the chunk_sectors field of the queue limits).
Introduce the nr_zones field to the request_queue structure to simplify
access to this information. Also, add the bitmap seq_zone_bitmap which
indicates which zones of the device are sequential zones (write
preferred or write required) and the bitmap seq_zones_wlock which
indicates if a zone is write locked, that is, if a write request
targeting a zone was dispatched to the device. These fields are
initialized by the low level block device driver (sd.c for ZBC/ZAC
disks). They are not initialized by stacking drivers (device mappers)
handling zoned block devices (e.g. dm-linear).
Using this, I/O schedulers can introduce zone write locking to control
request dispatching to a zoned block device and avoid write request
reordering by limiting to at most a single write request per zone
outside of the scheduler at any time.
Based on previous patches from Damien Le Moal.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[Damien]
* Fixed comments and identation in blkdev.h
* Changed helper functions
* Fixed this commit message
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now we track legacy requests with .q_usage_counter in commit 055f6e18e0
("block: Make q_usage_counter also track legacy requests"), but that
commit never runs and drains legacy queue before waiting for this counter
becoming zero, then IO hang is caused in the test of pulling disk during IO.
This patch fixes the issue by draining requests before waiting for
q_usage_counter becoming zero, both Mauricio and chenxiang reported this
issue, and observed that it can be fixed by this patch.
Link: https://marc.info/?l=linux-block&m=151192424731797&w=2
Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests")
Cc: Wen Xiong <wenxiong@us.ibm.com>
Tested-by: "chenxiang (M)" <chenxiang66@hisilicon.com>
Tested-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit de14829740
("blk-mq: introduce .get_budget and .put_budget in blk_mq_ops")
changes the function to return bool type, and then commit 1f460b63d4
("blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE")
changes it back to void, but the comment remains.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Even with a number of waitqueues, we can get into a situation where we
are heavily contended on the waitqueue lock. I got a report on spc1
where we're spending seconds doing this. Arguably the use case is nasty,
I reproduce it with one device and 1000 threads banging on the device.
But that doesn't mean we shouldn't be handling it better.
What ends up happening is that a thread will fail to get a tag, add
itself to the waitqueue, and subsequently get woken up when a tag is
freed - only to find itself going back to sleep on the waitqueue.
Instead of waking all threads, use an exclusive wait and wake up our
sbitmap batch count instead. This seems to work well for me (massive
improvement for this use case), and it survives basic testing. But I
haven't fully verified it yet.
An additional improvement is running the queue and checking for a new
tag BEFORE needing to add ourselves to the waitqueue.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If a bio is throttled and split after throttling, the bio could be
resubmited and enters the throttling again. This will cause part of the
bio to be charged multiple times. If the cgroup has an IO limit, the
double charge will significantly harm the performance. The bio split
becomes quite common after arbitrary bio size change.
To fix this, we always set the BIO_THROTTLED flag if a bio is throttled.
If the bio is cloned/split, we copy the flag to new bio too to avoid a
double charge. However, cloned bio could be directed to a new disk,
keeping the flag be a problem. The observation is we always set new disk
for the bio in this case, so we can clear the flag in bio_set_dev().
This issue exists for a long time, arbitrary bio size change just makes
it worse, so this should go into stable at least since v4.2.
V1-> V2: Not add extra field in bio based on discussion with Tejun
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: stable@vger.kernel.org
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit caa4b02476e3(blk-map: call blk_queue_bounce from blk_rq_append_bio)
moves blk_queue_bounce() into blk_rq_append_bio(), but don't consider
the fact that the bounced bio becomes invisible to caller since the
parameter type is 'struct bio *'. Make it a pointer to a pointer to
a bio, so the caller sees the right bio also after a bounce.
Fixes: caa4b02476 ("blk-map: call blk_queue_bounce from blk_rq_append_bio")
Cc: Christoph Hellwig <hch@lst.de>
Reported-by: Michele Ballabio <barra_cuda@katamail.com>
(handling failure of blk_rq_append_bio(), only call bio_get() after
blk_rq_append_bio() returns OK)
Tested-by: Michele Ballabio <barra_cuda@katamail.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit a8821f3f3("block: Improvements to bounce-buffer handling") tries
to make sure that the bio to .make_request_fn won't exceed BIO_MAX_PAGES,
but ignores that passthrough I/O can use blk_queue_bounce() too.
Especially, passthrough IO may not be sector-aligned, and the check
of 'sectors < bio_sectors(*bio_orig)' inside __blk_queue_bounce() may
become true even though the max bvec number doesn't exceed BIO_MAX_PAGES,
then cause the bio splitted, and the original passthrough bio is submited
to generic_make_request().
This patch fixes this issue by checking if the bio is passthrough IO,
and use bio_kmalloc() to allocate the cloned passthrough bio.
Cc: NeilBrown <neilb@suse.com>
Fixes: a8821f3f3("block: Improvements to bounce-buffer handling")
Tested-by: Michele Ballabio <barra_cuda@katamail.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 8cf4666020 ("kyber: fix hang on domain token wait queue") fixed
a hang caused by leaving wait entries on the domain token wait queue
after the __sbitmap_queue_get() retry succeeded, making that wait entry
a "dud" which won't in turn wake more entries up. However, we can also
get a dud entry if kyber_get_domain_token() fails once but is then
called again and succeeds. This can happen if the hardware queue is
rerun for some other reason, or, more likely, kyber_dispatch_request()
tries the same domain twice.
The fix is to remove our entry from the wait queue whenever we
successfully get a token. The only complication is that we might be on
one of many wait queues in the struct sbitmap_queue, but that's easily
fixed by remembering which wait queue we were put on.
While we're here, only initialize the wait queue entry once instead of
on every wait, and use spin_lock_irq() instead of spin_lock_irqsave(),
since this is always called from process context with irqs enabled.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block fixes from Jens Axboe:
"A selection of fixes/changes that should make it into this series.
This contains:
- NVMe, two merges, containing:
- pci-e, rdma, and fc fixes
- Device quirks
- Fix for a badblocks leak in null_blk
- bcache fix from Rui Hua for a race condition regression where
-EINTR was returned to upper layers that didn't expect it.
- Regression fix for blktrace for a bug introduced in this series.
- blktrace cleanup for cgroup id.
- bdi registration error handling.
- Small series with cleanups for blk-wbt.
- Various little fixes for typos and the like.
Nothing earth shattering, most important are the NVMe and bcache fixes"
* 'for-linus' of git://git.kernel.dk/linux-block: (34 commits)
nvme-pci: fix NULL pointer dereference in nvme_free_host_mem()
nvme-rdma: fix memory leak during queue allocation
blktrace: fix trace mutex deadlock
nvme-rdma: Use mr pool
nvme-rdma: Check remotely invalidated rkey matches our expected rkey
nvme-rdma: wait for local invalidation before completing a request
nvme-rdma: don't complete requests before a send work request has completed
nvme-rdma: don't suppress send completions
bcache: check return value of register_shrinker
bcache: recover data from backing when data is clean
bcache: Fix building error on MIPS
bcache: add a comment in journal bucket reading
nvme-fc: don't use bit masks for set/test_bit() numbers
blk-wbt: fix comments typo
blk-wbt: move wbt_clear_stat to common place in wbt_done
blk-sysfs: remove NULL pointer checking in queue_wb_lat_store
blk-wbt: remove duplicated setting in wbt_init
nvme-pci: add quirk for delay before CHK RDY for WDC SN200
block: remove useless assignment in bio_split
null_blk: fix dev->badblocks leak
...
wbt_done call wbt_clear_stat no matter current stat was tracked
or not, move it to common place.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
wbt_init doesn't set q->rq_wb to NULL, if wbt_init return 0,
so check return value is enough, remove NULL checking.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
rwb->wc and rwb->queue_depth were overwritten by wbt_set_write_cache and
wbt_set_queue_depth, remove the default setting.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove useless assignment to the variable "split" because the variable is
unconditionally assigned later.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: linux-block@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Kees Cook <keescook@chromium.org>
device_add_disk need do more safety error handle, so this patch just
add WARN_ON.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Adapted for current series by me.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull iov_iter updates from Al Viro:
- bio_{map,copy}_user_iov() series; those are cleanups - fixes from the
same pile went into mainline (and stable) in late September.
- fs/iomap.c iov_iter-related fixes
- new primitive - iov_iter_for_each_range(), which applies a function
to kernel-mapped segments of an iov_iter.
Usable for kvec and bvec ones, the latter does kmap()/kunmap() around
the callback. _Not_ usable for iovec- or pipe-backed iov_iter; the
latter is not hard to fix if the need ever appears, the former is by
design.
Another related primitive will have to wait for the next cycle - it
passes page + offset + size instead of pointer + size, and that one
will be usable for everything _except_ kvec. Unfortunately, that one
didn't get exposure in -next yet, so...
- a bit more lustre iov_iter work, including a use case for
iov_iter_for_each_range() (checksum calculation)
- vhost/scsi leak fix in failure exit
- misc cleanups and detritectomy...
* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (21 commits)
iomap_dio_actor(): fix iov_iter bugs
switch ksocknal_lib_recv_...() to use of iov_iter_for_each_range()
lustre: switch struct ksock_conn to iov_iter
vhost/scsi: switch to iov_iter_get_pages()
fix a page leak in vhost_scsi_iov_to_sgl() error recovery
new primitive: iov_iter_for_each_range()
lnet_return_rx_credits_locked: don't abuse list_entry
xen: don't open-code iov_iter_kvec()
orangefs: remove detritus from struct orangefs_kiocb_s
kill iov_shorten()
bio_alloc_map_data(): do bmd->iter setup right there
bio_copy_user_iov(): saner bio size calculation
bio_map_user_iov(): get rid of copying iov_iter
bio_copy_from_iter(): get rid of copying iov_iter
move more stuff down into bio_copy_user_iov()
blk_rq_map_user_iov(): move iov_iter_advance() down
bio_map_user_iov(): get rid of the iov_for_each()
bio_map_user_iov(): move alignment check into the main loop
don't rely upon subsequent bio_add_pc_page() calls failing
... and with iov_iter_get_pages_alloc() it becomes even simpler
...
Pull more block layer updates from Jens Axboe:
"A followup pull request, with some parts that either needed a bit more
testing before going in, merge sync, or just later arriving fixes.
This contains:
- Timer related updates from Kees. These were purposefully delayed
since I didn't want to pull in a later v4.14-rc tag to my block
tree.
- ide-cd prep sense buffer fix from Bart. Also delayed, as not to
clash with the late fix we put into 4.14-rc.
- Small BFQ updates series from Luca and Paolo.
- Single nvmet fix from James, fixing a non-functional case there.
- Bio fast clone fix from Michael, which made bcache return the wrong
data for some cases.
- Legacy IO path regression hang fix from Ming"
* 'for-linus' of git://git.kernel.dk/linux-block:
bio: ensure __bio_clone_fast copies bi_partno
nvmet_fc: fix better length checking
block: wake up all tasks blocked in get_request()
block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP
block, bfq: update blkio stats outside the scheduler lock
block, bfq: add missing invocations of bfqg_stats_update_io_add/remove
doc, block, bfq: update max IOPS sustainable with BFQ
ide: Make ide_cdrom_prep_fs() initialize the sense buffer pointer
md: Convert timers to use timer_setup()
block: swim3: Convert timers to use timer_setup()
block/aoe: Convert timers to use timer_setup()
amifloppy: Convert timers to use timer_setup()
block/floppy: Convert callback to pass timer_list
A new field was introduced in 74d46992e0, bi_partno, instead of using
bdev->bd_contains and encoding the partition information in the bi_bdev
field. __bio_clone_fast was changed to copy the disk information, but
not the partition information. At minimum, this regressed bcache and
caused data corruption.
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Fixes: 74d46992e0 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reported-by: Pavel Goran <via-bcache@pvgoran.name>
Reported-by: Campbell Steven <casteven@gmail.com>
Reviewed-by: Coly Li <colyli@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: <stable@vger.kernel.org> # 4.14
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Once blk_set_queue_dying() is done in blk_cleanup_queue(), we call
blk_freeze_queue() and wait for q->q_usage_counter becoming zero. But
if there are tasks blocked in get_request(), q->q_usage_counter can
never become zero. So we have to wake up all these tasks in
blk_set_queue_dying() first.
Fixes: 3ef28e83ab ("block: generic request_queue reference counting")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that we have a NUMA-aware version of kmalloc_array() we can use it
instead of kmalloc_node() without an overflow check in the size
calculation.
Link: http://lkml.kernel.org/r/20170927082038.3782-3-jthumshirn@suse.de
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Mike Marciniszyn <infinipath@intel.com>
Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
BFQ currently creates, and updates, its own instance of the whole
set of blkio statistics that cfq creates. Yet, from the comments
of Tejun Heo in [1], it turned out that most of these statistics
are meant/useful only for debugging. This commit makes BFQ create
the latter, debugging statistics only if the option
CONFIG_DEBUG_BLK_CGROUP is set.
By doing so, this commit also enables BFQ to enjoy a high perfomance
boost. The reason is that, if CONFIG_DEBUG_BLK_CGROUP is not set, then
BFQ has to update far fewer statistics, and, in particular, not the
heaviest to update. To give an idea of the benefits, if
CONFIG_DEBUG_BLK_CGROUP is not set, then, on an Intel i7-4850HQ, and
with 8 threads doing random I/O in parallel on null_blk (configured
with 0 latency), the throughput of BFQ grows from 310 to 400 KIOPS
(+30%). We have measured similar or even much higher boosts with other
CPUs: e.g., +45% with an ARM CortexTM-A53 Octa-core. Our results have
been obtained and can be reproduced very easily with the script in [1].
[1] https://www.spinics.net/lists/linux-block/msg18943.html
Suggested-by: Tejun Heo <tj@kernel.org>
Suggested-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bfq invokes various blkg_*stats_* functions to update the statistics
contained in the special files blkio.bfq.* in the blkio controller
groups, i.e., the I/O accounting related to the proportional-share
policy provided by bfq. The execution of these functions takes a
considerable percentage, about 40%, of the total per-request execution
time of bfq (i.e., of the sum of the execution time of all the bfq
functions that have to be executed to process an I/O request from its
creation to its destruction). This reduces the request-processing
rate sustainable by bfq noticeably, even on a multicore CPU. In fact,
the bfq functions that invoke blkg_*stats_* functions cannot be
executed in parallel with the rest of the code of bfq, because both
are executed under the same same per-device scheduler lock.
To reduce this slowdown, this commit moves, wherever possible, the
invocation of these functions (more precisely, of the bfq functions
that invoke blkg_*stats_* functions) outside the critical sections
protected by the scheduler lock.
With this change, and with all blkio.bfq.* statistics enabled, the
throughput grows, e.g., from 250 to 310 KIOPS (+25%) on an Intel
i7-4850HQ, in case of 8 threads doing random I/O in parallel on
null_blk, with the latter configured with 0 latency. We obtained the
same or higher throughput boosts, up to +30%, with other processors
(some figures are reported in the documentation). For our tests, we
used the script [1], with which our results can be easily reproduced.
NOTE. This commit still protects the invocation of blkg_*stats_*
functions with the request_queue lock, because the group these
functions are invoked on may otherwise disappear before or while these
functions are executed. Fortunately, tests without even this lock
show, by difference, that the serialization caused by this lock has a
little impact (at most ~5% of throughput reduction).
[1] https://github.com/Algodev-github/IOSpeed
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bfqg_stats_update_io_add and bfqg_stats_update_io_remove are to be
invoked, respectively, when an I/O request enters and when an I/O
request exits the scheduler. Unfortunately, bfq does not fully comply
with this scheme, because it does not invoke these functions for
requests that are inserted into or extracted from its priority
dispatch list. This commit fixes this mistake.
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull MD update from Shaohua Li:
"This update mostly includes bug fixes:
- md-cluster now supports raid10 from Guoqing
- raid5 PPL fixes from Artur
- badblock regression fix from Bo
- suspend hang related fixes from Neil
- raid5 reshape fixes from Neil
- raid1 freeze deadlock fix from Nate
- memleak fixes from Zdenek
- bitmap related fixes from Me and Tao
- other fixes and cleanups"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: (33 commits)
md: free unused memory after bitmap resize
md: release allocated bitset sync_set
md/bitmap: clear BITMAP_WRITE_ERROR bit before writing it to sb
md: be cautious about using ->curr_resync_completed for ->recovery_offset
badblocks: fix wrong return value in badblocks_set if badblocks are disabled
md: don't check MD_SB_CHANGE_CLEAN in md_allow_write
md-cluster: update document for raid10
md: remove redundant variable q
raid1: remove obsolete code in raid1_write_request
md-cluster: Use a small window for raid10 resync
md-cluster: Suspend writes in RAID10 if within range
md-cluster/raid10: set "do_balance = 0" if area is resyncing
md: use lockdep_assert_held
raid1: prevent freeze_array/wait_all_barriers deadlock
md: use TASK_IDLE instead of blocking signals
md: remove special meaning of ->quiesce(.., 2)
md: allow metadata update while suspending.
md: use mddev_suspend/resume instead of ->quiesce()
md: move suspend_hi/lo handling into core md code
md: don't call bitmap_create() while array is quiesced.
...
Pull core block layer updates from Jens Axboe:
"This is the main pull request for block storage for 4.15-rc1.
Nothing out of the ordinary in here, and no API changes or anything
like that. Just various new features for drivers, core changes, etc.
In particular, this pull request contains:
- A patch series from Bart, closing the whole on blk/scsi-mq queue
quescing.
- A series from Christoph, building towards hidden gendisks (for
multipath) and ability to move bio chains around.
- NVMe
- Support for native multipath for NVMe (Christoph).
- Userspace notifications for AENs (Keith).
- Command side-effects support (Keith).
- SGL support (Chaitanya Kulkarni)
- FC fixes and improvements (James Smart)
- Lots of fixes and tweaks (Various)
- bcache
- New maintainer (Michael Lyle)
- Writeback control improvements (Michael)
- Various fixes (Coly, Elena, Eric, Liang, et al)
- lightnvm updates, mostly centered around the pblk interface
(Javier, Hans, and Rakesh).
- Removal of unused bio/bvec kmap atomic interfaces (me, Christoph)
- Writeback series that fix the much discussed hundreds of millions
of sync-all units. This goes all the way, as discussed previously
(me).
- Fix for missing wakeup on writeback timer adjustments (Yafang
Shao).
- Fix laptop mode on blk-mq (me).
- {mq,name} tupple lookup for IO schedulers, allowing us to have
alias names. This means you can use 'deadline' on both !mq and on
mq (where it's called mq-deadline). (me).
- blktrace race fix, oopsing on sg load (me).
- blk-mq optimizations (me).
- Obscure waitqueue race fix for kyber (Omar).
- NBD fixes (Josef).
- Disable writeback throttling by default on bfq, like we do on cfq
(Luca Miccio).
- Series from Ming that enable us to treat flush requests on blk-mq
like any other request. This is a really nice cleanup.
- Series from Ming that improves merging on blk-mq with schedulers,
getting us closer to flipping the switch on scsi-mq again.
- BFQ updates (Paolo).
- blk-mq atomic flags memory ordering fixes (Peter Z).
- Loop cgroup support (Shaohua).
- Lots of minor fixes from lots of different folks, both for core and
driver code"
* 'for-4.15/block' of git://git.kernel.dk/linux-block: (294 commits)
nvme: fix visibility of "uuid" ns attribute
blk-mq: fixup some comment typos and lengths
ide: ide-atapi: fix compile error with defining macro DEBUG
blk-mq: improve tag waiting setup for non-shared tags
brd: remove unused brd_mutex
blk-mq: only run the hardware queue if IO is pending
block: avoid null pointer dereference on null disk
fs: guard_bio_eod() needs to consider partitions
xtensa/simdisk: fix compile error
nvme: expose subsys attribute to sysfs
nvme: create 'slaves' and 'holders' entries for hidden controllers
block: create 'slaves' and 'holders' entries for hidden gendisks
nvme: also expose the namespace identification sysfs files for mpath nodes
nvme: implement multipath access to nvme subsystems
nvme: track shared namespaces
nvme: introduce a nvme_ns_ids structure
nvme: track subsystems
block, nvme: Introduce blk_mq_req_flags_t
block, scsi: Make SCSI quiesce and resume work reliably
block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
...
If we run out of driver tags, we currently treat shared and non-shared
tags the same - both cases hook into the tag waitqueue. This is a bit
more costly than it needs to be on unshared tags, since we have to both
grab the hctx lock, and the waitqueue lock (and disable interrupts).
For the non-shared case, we can simply mark the queue as needing a
restart.
Split blk_mq_dispatch_wait_add() to account for both cases, and
rename it to blk_mq_mark_tag_wait() to better reflect what it
does now.
Without this patch, shared and non-shared performance is about the same
with 4 fio thread hammering on a single null_blk device (~410K, at 75%
sys). With the patch, the shared case is the same, but the non-shared
tags case runs at 431K at 71% sys.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently we are inconsistent in when we decide to run the queue. Using
blk_mq_run_hw_queues() we check if the hctx has pending IO before
running it, but we don't do that from the individual queue run function,
blk_mq_run_hw_queue(). This results in a lot of extra and pointless
queue runs, potentially, on flush requests and (much worse) on tag
starvation situations. This is observable just looking at top output,
with lots of kworkers active. For the !async runs, it just adds to the
CPU overhead of blk-mq.
Move the has-pending check into the run function instead of having
callers do it.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is possible that the pointer disk can be null and hence
we can get a null pointer deference when accessing disk->flags.
Add a null pointer check to avoid the dereference.
Detected by CoverityScan, CID#1461133 ("Explicit null dereferenced")
Fixes: 8ddcd65325 ("block: introduce GENHD_FL_HIDDEN")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When creating nvme multipath devices we should populate the 'slaves' and
'holders' directorys properly to aid userspace topology detection.
Signed-off-by: Hannes Reinecke <hare@suse.com>
[hch: split from a larger patch]
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Several block layer and NVMe core functions accept a combination
of BLK_MQ_REQ_* flags through the 'flags' argument but there is
no verification at compile time whether the right type of block
layer flags is passed. Make it possible for sparse to verify this.
This patch does not change any functionality.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: linux-nvme@lists.infradead.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The contexts from which a SCSI device can be quiesced or resumed are:
* Writing into /sys/class/scsi_device/*/device/state.
* SCSI parallel (SPI) domain validation.
* The SCSI device power management methods. See also scsi_bus_pm_ops.
It is essential during suspend and resume that neither the filesystem
state nor the filesystem metadata in RAM changes. This is why while
the hibernation image is being written or restored that SCSI devices
are quiesced. The SCSI core quiesces devices through scsi_device_quiesce()
and scsi_device_resume(). In the SDEV_QUIESCE state execution of
non-preempt requests is deferred. This is realized by returning
BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI
devices. Avoid that a full queue prevents power management requests
to be submitted by deferring allocation of non-preempt requests for
devices in the quiesced state. This patch has been tested by running
the following commands and by verifying that after each resume the
fio job was still running:
for ((i=0; i<10; i++)); do
(
cd /sys/block/md0/md &&
while true; do
[ "$(<sync_action)" = "idle" ] && echo check > sync_action
sleep 1
done
) &
pids=($!)
for d in /sys/class/block/sd*[a-z]; do
bdev=${d#/sys/class/block/}
hcil=$(readlink "$d/device")
hcil=${hcil#../../../}
echo 4 > "$d/queue/nr_requests"
echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth"
fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 \
--rw=randread --ioengine=libaio --numjobs=4 --iodepth=16 \
--iodepth_batch=1 --thread --loops=$((2**31)) &
pids+=($!)
done
sleep 1
echo "$(date) Hibernating ..." >>hibernate-test-log.txt
systemctl hibernate
sleep 10
kill "${pids[@]}"
echo idle > /sys/block/md0/md/sync_action
wait
echo "$(date) Done." >>hibernate-test-log.txt
done
Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348).
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This flag will be used in the next patch to let the block layer
core know whether or not a SCSI request queue has been quiesced.
A quiesced SCSI queue namely only processes RQF_PREEMPT requests.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Set RQF_PREEMPT if BLK_MQ_REQ_PREEMPT is passed to
blk_get_request_flags().
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A side effect of this patch is that the GFP mask that is passed to
several allocation functions in the legacy block layer is changed
from GFP_KERNEL into __GFP_DIRECT_RECLAIM.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch makes it possible to pause request allocation for
the legacy block layer by calling blk_mq_freeze_queue() and
blk_mq_unfreeze_queue().
Signed-off-by: Ming Lei <ming.lei@redhat.com>
[ bvanassche: Combined two patches into one, edited a comment and made sure
REQ_NOWAIT is handled properly in blk_old_get_request() ]
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Martin Steigerwald <martin@lichtvoll.de>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch attempts to make the case of hctx re-running on driver tag
failure more robust. Without this patch, it's pretty easy to trigger a
stall condition with shared tags. An example is using null_blk like
this:
modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 submit_queues=1 hw_queue_depth=1
which sets up 4 devices, sharing the same tag set with a depth of 1.
Running a fio job ala:
[global]
bs=4k
rw=randread
norandommap
direct=1
ioengine=libaio
iodepth=4
[nullb0]
filename=/dev/nullb0
[nullb1]
filename=/dev/nullb1
[nullb2]
filename=/dev/nullb2
[nullb3]
filename=/dev/nullb3
will inevitably end with one or more threads being stuck waiting for a
scheduler tag. That IO is then stuck forever, until someone else
triggers a run of the queue.
Ensure that we always re-run the hardware queue, if the driver tag we
were waiting for got freed before we added our leftover request entries
back on the dispatch list.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Avoid that removal of a request queue sporadically triggers the
following warning:
list_del corruption. next->prev should be ffff8807d649b970, but was 6b6b6b6b6b6b6b6b
WARNING: CPU: 3 PID: 342 at lib/list_debug.c:56 __list_del_entry_valid+0x92/0xa0
Call Trace:
process_one_work+0x11b/0x660
worker_thread+0x3d/0x3b0
kthread+0x129/0x140
ret_from_fork+0x27/0x40
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We have to put the driver tag if dispatch budget can't be got, otherwise
it might cause IO deadlock, especially in case that size of tags is very
small.
Fixes: de1482974080(blk-mq: introduce .get_budget and .put_budget in blk_mq_ops)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This helper doesn't buy us much over calling kmap_atomic directly.
In fact in the only caller it does a bit of useless work as the
caller already has the bvec at hand, and said caller would even
buggy for a multi-segment bio due to the use of this helper.
So just remove it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This reverts commit 358a3a6bcc.
We have cases that aren't covered 100% in the drivers, so for now
we have to retain the shared tag restart loops.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The idea behind it is simple:
1) for none scheduler, driver tag has to be borrowed for flush rq,
otherwise we may run out of tag, and that causes an IO hang. And
get/put driver tag is actually noop for none, so reordering tags
isn't necessary at all.
2) for a real I/O scheduler, we need not allocate a driver tag upfront
for flush rq. It works just fine to follow the same approach as
normal requests: allocate driver tag for each rq just before calling
->queue_rq().
One driver visible change is that the driver tag isn't shared in the
flush request sequence. That won't be a problem, since we always do that
in legacy path.
Then flush rq need not be treated specially wrt. get/put driver tag.
This cleans up the code - for instance, reorder_tags_to_front() can be
removed, and we needn't worry about request ordering in dispatch list
for avoiding I/O deadlock.
Also we have to put the driver tag before requeueing.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need this helper to put the driver tag for flush rq, since we will
not share tag in the flush request sequence in the following patch
in case that I/O scheduler is applied.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In case of IO scheduler we always pre-allocate one driver tag before
calling blk_insert_flush(), and flush request will be marked as
RQF_FLUSH_SEQ once it is in flush machinery.
So if RQF_FLUSH_SEQ isn't set, we call blk_insert_flush() to handle
the request, otherwise the flush request is dispatched to ->dispatch
list directly.
This is a preparation patch for not preallocating a driver tag for flush
requests, and for not treating flush requests as a special case. This is
similar to what the legacy path does.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In the following patch, we will use RQF_FLUSH_SEQ to decide:
1) if the flag isn't set, the flush rq need to be inserted via
blk_insert_flush()
2) otherwise, the flush rq need to be dispatched directly since
it is in flush machinery now.
So we use blk_mq_request_bypass_insert() for requests of bypassing
flush machinery, just like the legacy path did.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Block flush need this function without running the queue, so add a
parameter controlling whether we run it or not.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_insert_flush() should only insert request since run queue always
follows it.
In case of bypassing flush, we don't need to run queue because every
blk_insert_flush() follows one run queue.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When freeing the driver tag of the next rq with an I/O scheduler
configured, we get the first entry of the list. However, this can
race with requeue of a request, and we end up getting the wrong request
from the head of the list. Free the driver tag of next rq before the
failed one is requeued in the failure branch of queue_rq callback.
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It is enough to just check if we can get the budget via .get_budget().
And we don't need to deal with device state change in .get_budget().
For SCSI, one issue to be fixed is that we have to call
scsi_mq_uninit_cmd() to free allocated ressources if SCSI device fails
to handle the request. And it isn't enough to simply call
blk_mq_end_request() to do that if this request is marked as
RQF_DONTPREP.
Fixes: 0df21c86bdbf(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need to look for an active PM request until the next softbarrier
instead of looking for the first non-PM request. Otherwise any cause
of request reordering might starve the PM request(s).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_mq_get_tag() can modify data->ctx. This means that in the
error path of blk_mq_get_request() data->ctx should be passed to
blk_mq_put_ctx() instead of local_ctx. Note: since blk_mq_put_ctx()
ignores its argument, this patch does not change any functionality.
References: commit 1ad43c0078 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
MD's rdev_set_badblocks() expects that badblocks_set() returns 1 if
badblocks are disabled, otherwise, rdev_set_badblocks() will record
superblock changes and return success in that case and md will fail to
report an IO error which it should.
This bug has existed since badblocks were introduced in commit
9e0e252a04 ("badblocks: Add core badblock management code").
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Acked-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
if blk-mq use "none" io scheduler, nr_request get a wrong value when
input a number > tag_set->queue_depth. blk_mq_tag_update_depth will get
the smaller one min(nr, set->queue_depth), and then q->nr_request get a
wrong value.
Reproduce:
echo none > /sys/block/nvme0n1/queue/scheduler
echo 1000000 > /sys/block/nvme0n1/queue/nr_requests
cat /sys/block/nvme0n1/queue/nr_requests
1000000
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
That we we can also poll non blk-mq queues. Mostly needed for
the NVMe multipath code, but could also be useful elsewhere.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With this flag a driver can create a gendisk that can be used for I/O
submission inside the kernel, but which is not registered as user
facing block device. This will be useful for the NVMe multipath
implementation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The hidden gendisks introduced in the next patch need to keep the dev
field in their struct device empty so that udev won't try to create
block device nodes for them. To support that rewrite disk_devt to
look at the major and first_minor fields in the gendisk itself instead
of looking into the struct device.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This helpers allows to bounce steal the uncompleted bios from a request so
that they can be reissued on another path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This helper allows reinserting a bio into a new queue without much
overhead, but requires all queue limits to be the same for the upper
and lower queues, and it does not provide any recursion preventions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Javier González <javier@cnexlabs.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull NVMe changes from Christoph:
"Below are the currently queue nvme updates for Linux 4.15. There are
a few more things that could make it for this merge window, but I'd
like to get things into linux-next, especially for the unlikely case
that Linus decided to cut -rc8.
Highlights:
- support for SGLs in the PCIe driver (Chaitanya Kulkarni)
- disable I/O schedulers for the admin queue (Israel Rukshin)
- various Fibre Channel fixes and enhancements (James Smart)
- various refactoring for better code sharing between transports
(Sagi Grimberg and me)
as well as lots of little bits from various contributors."
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI restarts its queue in scsi_end_request() automatically, so we don't
need to handle this case in blk-mq.
Especailly any request won't be dequeued in this case, we needn't to
worry about IO hang caused by restart vs. dispatch.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now restart is used in the following cases, and TAG_SHARED is for
SCSI only.
1) .get_budget() returns BLK_STS_RESOURCE
- if resource in target/host level isn't satisfied, this SCSI device
will be added in shost->starved_list, and the whole queue will be rerun
(via SCSI's built-in RESTART) in scsi_end_request() after any request
initiated from this host/targe is completed. Forget to mention, host level
resource can't be an issue for blk-mq at all.
- the same is true if resource in the queue level isn't satisfied.
- if there isn't outstanding request on this queue, then SCSI's RESTART
can't work(blk-mq's can't work too), and the queue will be run after
SCSI_QUEUE_DELAY, and finally all starved sdevs will be handled by SCSI's
RESTART when this request is finished
2) scsi_dispatch_cmd() returns BLK_STS_RESOURCE
- if there isn't onprogressing request on this queue, the queue
will be run after SCSI_QUEUE_DELAY
- otherwise, SCSI's RESTART covers the rerun.
3) blk_mq_get_driver_tag() failed
- BLK_MQ_S_TAG_WAITING covers the cross-queue RESTART for driver
allocation.
In one word, SCSI's built-in RESTART is enough to cover the queue
rerun, and we don't need to pay special attention to TAG_SHARED wrt. restart.
In my test on scsi_debug(8 luns), this patch improves IOPS by 20% ~ 30% when
running I/O on these 8 luns concurrently.
Aslo Roman Pen reported the current RESTART is very expensive especialy
when there are lots of LUNs attached in one host, such as in his
test, RESTART causes half of IOPS be cut.
Fixes: https://marc.info/?l=linux-kernel&m=150832216727524&w=2
Fixes: 6d8c6c0f97 ("blk-mq: Restart a single queue if tag sets are shared")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
SCSI devices use host-wide tagset, and the shared driver tag space is
often quite big. However, there is also a queue depth for each lun(
.cmd_per_lun), which is often small, for example, on both lpfc and
qla2xxx, .cmd_per_lun is just 3.
So lots of requests may stay in sw queue, and we always flush all
belonging to same hw queue and dispatch them all to driver.
Unfortunately it is easy to cause queue busy because of the small
.cmd_per_lun. Once these requests are flushed out, they have to stay in
hctx->dispatch, and no bio merge can happen on these requests, and
sequential IO performance is harmed.
This patch introduces blk_mq_dequeue_from_ctx for dequeuing a request
from a sw queue, so that we can dispatch them in scheduler's way. We can
then avoid dequeueing too many requests from sw queue, since we don't
flush ->dispatch completely.
This patch improves dispatching from sw queue by using the .get_budget
and .put_budget callbacks.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For SCSI devices, there is often a per-request-queue depth, which needs
to be respected before queuing one request.
Currently blk-mq always dequeues the request first, then calls
.queue_rq() to dispatch the request to lld. One obvious issue with this
approach is that I/O merging may not be successful, because when the
per-request-queue depth can't be respected, .queue_rq() has to return
BLK_STS_RESOURCE, and then this request has to stay in hctx->dispatch
list. This means it never gets a chance to be merged with other IO.
This patch introduces .get_budget and .put_budget callback in blk_mq_ops,
then we can try to get reserved budget first before dequeuing request.
If the budget for queueing I/O can't be satisfied, we don't need to
dequeue request at all. Hence the request can be left in the IO
scheduler queue, for more merging opportunities.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There may be request in sw queue, and not fetched to domain queue
yet, so check it in kyber_has_work().
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
So that it becomes easy to support to dispatch from sw queue in the
following patch.
No functional change.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Suggested-by: Christoph Hellwig <hch@lst.de> # for simplifying dispatch logic
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When the hw queue is busy, we shouldn't take requests from the scheduler
queue any more, otherwise it is difficult to do IO merge.
This patch fixes the awful IO performance on some SCSI devices(lpfc,
qla2xxx, ...) when mq-deadline/kyber is used by not taking requests if
hw queue is busy.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make sure that if the timeout timer fires after a queue has been
marked "dying" that the affected requests are finished.
Reported-by: chenxiang (M) <chenxiang66@hisilicon.com>
Fixes: commit 287922eb0b ("block: defer timeouts to a workqueue")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Tested-by: chenxiang (M) <chenxiang66@hisilicon.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Darrick posted the following warning and Dave Chinner analyzed it:
> ======================================================
> WARNING: possible circular locking dependency detected
> 4.14.0-rc1-fixes #1 Tainted: G W
> ------------------------------------------------------
> loop0/31693 is trying to acquire lock:
> (&(&ip->i_mmaplock)->mr_lock){++++}, at: [<ffffffffa00f1b0c>] xfs_ilock+0x23c/0x330 [xfs]
>
> but now in release context of a crosslock acquired at the following:
> ((complete)&ret.event){+.+.}, at: [<ffffffff81326c1f>] submit_bio_wait+0x7f/0xb0
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #2 ((complete)&ret.event){+.+.}:
> lock_acquire+0xab/0x200
> wait_for_completion_io+0x4e/0x1a0
> submit_bio_wait+0x7f/0xb0
> blkdev_issue_zeroout+0x71/0xa0
> xfs_bmapi_convert_unwritten+0x11f/0x1d0 [xfs]
> xfs_bmapi_write+0x374/0x11f0 [xfs]
> xfs_iomap_write_direct+0x2ac/0x430 [xfs]
> xfs_file_iomap_begin+0x20d/0xd50 [xfs]
> iomap_apply+0x43/0xe0
> dax_iomap_rw+0x89/0xf0
> xfs_file_dax_write+0xcc/0x220 [xfs]
> xfs_file_write_iter+0xf0/0x130 [xfs]
> __vfs_write+0xd9/0x150
> vfs_write+0xc8/0x1c0
> SyS_write+0x45/0xa0
> entry_SYSCALL_64_fastpath+0x1f/0xbe
>
> -> #1 (&xfs_nondir_ilock_class){++++}:
> lock_acquire+0xab/0x200
> down_write_nested+0x4a/0xb0
> xfs_ilock+0x263/0x330 [xfs]
> xfs_setattr_size+0x152/0x370 [xfs]
> xfs_vn_setattr+0x6b/0x90 [xfs]
> notify_change+0x27d/0x3f0
> do_truncate+0x5b/0x90
> path_openat+0x237/0xa90
> do_filp_open+0x8a/0xf0
> do_sys_open+0x11c/0x1f0
> entry_SYSCALL_64_fastpath+0x1f/0xbe
>
> -> #0 (&(&ip->i_mmaplock)->mr_lock){++++}:
> up_write+0x1c/0x40
> xfs_iunlock+0x1d0/0x310 [xfs]
> xfs_file_fallocate+0x8a/0x310 [xfs]
> loop_queue_work+0xb7/0x8d0
> kthread_worker_fn+0xb9/0x1f0
>
> Chain exists of:
> &(&ip->i_mmaplock)->mr_lock --> &xfs_nondir_ilock_class --> (complete)&ret.event
>
> Possible unsafe locking scenario by crosslock:
>
> CPU0 CPU1
> ---- ----
> lock(&xfs_nondir_ilock_class);
> lock((complete)&ret.event);
> lock(&(&ip->i_mmaplock)->mr_lock);
> unlock((complete)&ret.event);
>
> *** DEADLOCK ***
The warning is a false positive, caused by the fact that all
wait_for_completion()s in submit_bio_wait() are waiting with the same
lock class.
However, some bios have nothing to do with others, for example in the case
of loop devices, there's no direct connection between the bios of an upper
device and the bios of a lower device(=loop device).
The safest way to assign different lock classes to different devices is
to do it for each gendisk. In other words, this patch assigns a
lockdep_map per gendisk and uses it when initializing completion in
submit_bio_wait().
Analyzed-by: Dave Chinner <david@fromorbit.com>
Reported-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: amir73il@gmail.com
Cc: axboe@kernel.dk
Cc: david@fromorbit.com
Cc: hch@infradead.org
Cc: idryomov@gmail.com
Cc: johan@kernel.org
Cc: johannes.berg@intel.com
Cc: kernel-team@lge.com
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1508921765-15396-10-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The scheduler framework now supports looking up the appropriate
scheduler with the {name,mq} tupple. We can register mq-deadline
with the alias of 'deadline', so that switching to 'deadline'
will do the right thing based on the type of driver attached to
it.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since we now lookup elevator types with the appropriate multiqueue
capability, allow schedulers to register with an alias alongside
the real name. This is in preparation for allowing 'mq-deadline'
to register an alias of 'deadline' as well.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If an IO scheduler is selected via elevator= and it doesn't match
the driver in question wrt blk-mq support, then we fail to boot.
The elevator= parameter is deprecated and only supported for
non-mq devices. Augment the elevator lookup API so that we
pass in if we're looking for an mq capable scheduler or not,
so that we only ever return a valid type for the queue in
question.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196695
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sd_config_write_same() ignores ->max_ws_blocks == 0 and resets it to
permit trying WRITE SAME on older SCSI devices, unless ->no_write_same
is set. Because REQ_OP_WRITE_ZEROES is implemented in terms of WRITE
SAME, blkdev_issue_zeroout() may fail with -EREMOTEIO:
$ fallocate -zn -l 1k /dev/sdg
fallocate: fallocate failed: Remote I/O error
$ fallocate -zn -l 1k /dev/sdg # OK
$ fallocate -zn -l 1k /dev/sdg # OK
The following calls succeed because sd_done() sets ->no_write_same in
response to a sense that would become BLK_STS_TARGET/-EREMOTEIO, causing
__blkdev_issue_zeroout() to fall back to generating ZERO_PAGE bios.
This means blkdev_issue_zeroout() must cope with WRITE ZEROES failing
and fall back to manually zeroing, unless BLKDEV_ZERO_NOFALLBACK is
specified. For BLKDEV_ZERO_NOFALLBACK case, return -EOPNOTSUPP if
sd_done() has just set ->no_write_same thus indicating lack of offload
support.
Fixes: c20cfc27a4 ("block: stop using blkdev_issue_write_same for zeroing")
Cc: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkdev_issue_zeroout() will use this in !BLKDEV_ZERO_NOFALLBACK case.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Check for CAP_SYS_ADMIN before calling into the driver, similar to
blkdev_flushbuf(). This is safer and can spare a check in the driver.
(Currently BLKROSET is overridden by md and rbd, rbd is missing the
check. md has the check, but it covers a lot more than BLKROSET.)
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is reasonable drop page cache on discard, otherwise that pages may
be written by writeback second later, so thin provision devices will
not be happy. This seems to be a security leak in case of secure discard case.
Also add check for queue_discard flag on early stage.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Iterator helper to apply a function on all the
tags in a given tagset. export it as it will be used
outside the block layer later on.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
When we're getting a domain token, if we fail to get a token on our
first attempt, we put the current hardware queue on a wait queue and
then try again just in case a token was freed after our initial attempt
but before we got on the wait queue. If this second attempt succeeds, we
currently leave the hardware queue on the wait queue. Usually this is
okay; we'll just run the hardware queue one extra time when another
token is freed. However, if the hardware queue doesn't have any other
requests waiting, then when it it gets the extra wakeup, it won't have
anything to free and therefore won't wake up any other hardware queues.
If tokens are limited, then we won't make forward progress and the
device will hang.
Reported-by: Bin Zha <zhabin.zb@alibaba-inc.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sphinx treats symbols that end with '_' as a kind of special
documentation indicator, so fix that by adding an ending '*'
to it.
../block/bio.c:404: ERROR: Unknown target name: "gfp".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
it's a bounce buffer; we don't *care* how badly is the real
source/destination fragmented, all that matters is the total
size.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... they might actually succeed in some cases (when we are at the
queue-imposed segments limit, the next page is not mergable with
the last one we'd got in, but the first page covered by the next
iovec *is* mergable). Make sure that once it's failed, we are
done with that bio.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since "block: support large requests in blk_rq_map_user_iov" we
started to call it with partially drained iter; that works fine
on the write side, but reads create a copy of iter for completion
time. And that needs to take the possibility of ->iov_iter != 0
into account...
Cc: stable@vger.kernel.org #v4.5+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
we need to take care of failure exit as well - pages already
in bio should be dropped by analogue of bio_unmap_pages(),
since their refcounts had been bumped only once per reference
in bio.
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
bio_map_user_iov and bio_unmap_user do unbalanced pages refcounting if
IO vector has small consecutive buffers belonging to the same page.
bio_add_pc_page merges them into one, but the page reference is never
dropped.
Cc: stable@vger.kernel.org
Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Legacy queue sets request's request_list, mq doesn't. This makes mq does
the same thing, so we can find cgroup of a request. Note, we really
only use blkg field of request_list, it's pointless to allocate mempool
for request_list in mq case.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix two issues:
- the per-cpu stat flush is unnecessary, nobody uses per-cpu stat except
sum it to global stat. We can do the calculation there. The flush just
wastes cpu time.
- some fields are signed int/s64. I don't see the point.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A null pointer dereference can occur when blkcg is removed manually
with writeback IOs inflight. This is caused by the following case:
Writeback kworker submit the bio and set bio->bi_cg_private to tg
in blk_throtl_assoc_bio.
Then we remove the block cgroup manually, the blkg and tg would be
freed if there is no request inflight.
When the submitted bio come back, blk_throtl_bio_endio() fetch the tg
which was already freed.
Fix this by increasing the refcount of blkg in funcion
blk_throtl_assoc_bio() so that the blkg will not be freed until the
bio_endio called.
Reviewed-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jiufei Xue <jiufei.xjf@alibaba-inc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The commit "block, bfq: decrease burst size when queues in burst
exit" introduced the decrement of burst_size on the removal of a
bfq_queue from the burst list. Unfortunately, this decrement can
happen to be performed even when burst size is already equal to 0,
because of unbalanced decrements. A description follows of the cause
of these unbalanced decrements, namely a wrong assumption, and of the
way how this wrong assumption leads to unbalanced decrements.
The wrong assumption is that a bfq_queue can exit only if the process
associated with the bfq_queue has exited. This is false, because a
bfq_queue, say Q, may exit also as a consequence of a merge with
another bfq_queue. In this case, Q exits because the I/O of its
associated process has been redirected to another bfq_queue.
The decrement unbalance occurs because Q may then be re-created after
a split, and added back to the current burst list, *without*
incrementing burst_size. burst_size is not incremented because Q is
not a new bfq_queue added to the burst list, but a bfq_queue only
temporarily removed from the list, and, before the commit "bfq-sq,
bfq-mq: decrease burst size when queues in burst exit", burst_size was
not decremented when Q was removed.
This commit addresses this issue by just checking whether the exiting
bfq_queue is a merged bfq_queue, and, in that case, not decrementing
burst_size. Unfortunately, this still leaves room for unbalanced
decrements, in the following rarer case: on a split, the bfq_queue
happens to be inserted into a different burst list than that it was
removed from when merged. If this happens, the number of elements in
the new burst list becomes higher than burst_size (by one). When the
bfq_queue then exits, it is of course not in a merged state any
longer, thus burst_size is decremented, which results in an unbalanced
decrement. To handle this sporadic, unlucky case in a simple way,
this commit also checks that burst_size is larger than 0 before
decrementing it.
Finally, this commit removes an useless, extra check: the check that
the bfq_queue is sync, performed before checking whether the bfq_queue
is in the burst list. This extra check is redundant, because only sync
bfq_queues can be inserted into the burst list.
Fixes: 7cb04004fa ("block, bfq: decrease burst size when queues in burst exit")
Reported-by: Philip Müller <philm@manjaro.org>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Philip Müller <philm@manjaro.org>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Similarly to CFQ, BFQ has its write-throttling heuristics, and it
is better not to combine them with further write-throttling
heuristics of a different nature.
So this commit disables write-back throttling for a device if BFQ
is used as I/O scheduler for that device.
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch removes redundant checks for null values on bio_pool and
bvec_pool.
Found using make coccicheck M=block/ on linux-net tree on the
next-20170929 tag.
Signed-off-by: Tim Hansen <devtimhansen@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
mempool_destroy() already checks for a NULL value being passed in, this
eliminates duplicate checks.
This was caught by running make coccicheck M=block/ on linus' tree on
commit 77ede3a014 (current head as of this
patch).
Reviewed-by: Kyle Fortin <kyle.fortin@oracle.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Tim Hansen <devtimhansen@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already have a queue_is_rq_based helper to check if a request_queue
is request based, so we can remove the flag for it.
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For memory ordering guarantees on stores, we need to ensure that
these two bits share the same byte of storage in the unsigned
long. Add a comment as to why, and a BUILD_BUG_ON() to ensure that
we don't violate this requirement.
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Attempt to untangle the ordering in blk-mq. The patch introducing the
single smp_mb__before_atomic() is obviously broken in that it doesn't
clearly specify a pairing barrier and an obtained guarantee.
The comment is further misleading in that it hints that the
deadline store and the COMPLETE store also need to be ordered, but
AFAICT there is no such dependency. However what does appear to be
important is the clear happening _after_ the store, and that worked by
pure accident.
This clarifies blk_mq_start_request() -- we should not get there with
STARTING set -- this simplifies the code and makes the barrier usage
sane (the old code could be read to allow not having _any_ atomic after
the barrier, in which case the barrier hasn't got anything to order). We
then also introduce the missing pairing barrier for it.
Also down-grade the barrier to smp_wmb(), this is cheaper for
PowerPC/ARM and doesn't cost anything extra on x86.
And it documents the STARTING vs COMPLETE ordering. Although I've not
been entirely successful in reverse engineering the blk-mq state
machine so there might still be more funnies around timeout vs
requeue.
If I got anything wrong, feel free to educate me by adding comments to
clarify things ;-)
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Fixes: 538b753418 ("blk-mq: request deadline must be visible before marking rq as started")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When under memory-pressure it is possible that the mempool which backs
the 'struct request_queue' will make use of up to BLKDEV_MIN_RQ count
emergency buffers - in case it can't get a regular allocation. These
buffers are preallocated and once they are also used, they are
re-supplied with old finished requests from the same request_queue (see
mempool_free()).
The bug is, when re-supplying the emergency pool, the old requests are
not again ran through the callback mempool_t->alloc(), and thus also not
through the callback bsg_init_rq(). Thus we skip initialization, and
while the sense-buffer still should be good, scsi_request->cmd might
have become to be an invalid pointer in the meantime. When the request
is initialized in bsg.c, and the user's CDB is larger than BLK_MAX_CDB,
bsg will replace it with a custom allocated buffer, which is freed when
the user's command is finished, thus it dangles afterwards. When next a
command is sent by the user that has a smaller/similar CDB as
BLK_MAX_CDB, bsg will assume that scsi_request->cmd is backed by
scsi_request->__cmd, will not make a custom allocation, and write into
undefined memory.
Fix this by splitting bsg_init_rq() into two functions:
- bsg_init_rq() is changed to only do the allocation of the
sense-buffer, which is used to back the bsg job's reply buffer. This
pointer should never change during the lifetime of a scsi_request, so
it doesn't need re-initialization.
- bsg_initialize_rq() is a new function that makes use of
'struct request_queue's initialize_rq_fn callback (which was
introduced in v4.12). This is always called before the request is
given out via blk_get_request(). This function does the remaining
initialization that was previously done in bsg_init_rq(), and will
also do it when the request is taken from the emergency-pool of the
backing mempool.
Fixes: 50b4d48552 ("bsg-lib: fix kernel panic resulting from missing allocation of reply-buffer")
Cc: <stable@vger.kernel.org> # 4.11+
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In blk_mq_debugfs_register(), I remembered to set up the per-hctx sched
directories if a default scheduler was already configured by
blk_mq_sched_init() from blk_mq_init_allocated_queue(), but I didn't do
the same for the device-wide sched directory. Fix it.
Fixes: d332ce0918 ("blk-mq-debugfs: allow schedulers to register debugfs attributes")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is a case which will lead to io stall. The case is described as
follows.
/test1
|-subtest1
/test2
|-subtest2
And subtest1 and subtest2 each has 32 queued bios already.
Now upgrade to max. In throtl_upgrade_state, it will try to dispatch
bios as follows:
1) tg=subtest1, do nothing;
2) tg=test1, transfer 32 queued bios from subtest1 to test1; no pending
left, no need to schedule next dispatch;
3) tg=subtest2, do nothing;
4) tg=test2, transfer 32 queued bios from subtest2 to test2; no pending
left, no need to schedule next dispatch;
5) tg=/, transfer 8 queued bios from test1 to /, 8 queued bios from
test2 to /, 8 queued bios from test1 to /, and 8 queued bios from test2
to /; note that test1 and test2 each still has 16 queued bios left;
6) tg=/, try to schedule next dispatch, but since disptime is now
(update in tg_update_disptime, wait=0), pending timer is not scheduled
in fact;
7) In throtl_upgrade_state it totally dispatches 32 queued bios and with
32 left. test1 and test2 each has 16 queued bios;
8) throtl_pending_timer_fn sees the left over bios, but could do
nothing, because throtl_select_dispatch returns 0, and test1/test2 has
no pending tg.
The blktrace shows the following:
8,32 0 0 2.539007641 0 m N throtl upgrade to max
8,32 0 0 2.539072267 0 m N throtl /test2 dispatch nr_queued=16 read=0 write=16
8,32 7 0 2.539077142 0 m N throtl /test1 dispatch nr_queued=16 read=0 write=16
So force schedule dispatch if there are pending children.
Reviewed-by: Shaohua Li <shli@fb.com>
Signed-off-by: Joseph Qi <qijiang.qj@alibaba-inc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No need to have this helper inline in a header. Also drop the __ prefix.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If many queues belonging to the same group happen to be created
shortly after each other, then the concurrent processes associated
with these queues have typically a common goal, and they get it done
as soon as possible if not hampered by device idling. Examples are
processes spawned by git grep, or by systemd during boot. As for
device idling, this mechanism is currently necessary for weight
raising to succeed in its goal: privileging I/O. In view of these
facts, BFQ does not provide the above queues with either weight
raising or device idling.
On the other hand, a burst of queue creations may be caused also by
the start-up of a complex application. In this case, these queues need
usually to be served one after the other, and as quickly as possible,
to maximise responsiveness. Therefore, in this case the best strategy
is to weight-raise all the queues created during the burst, i.e., the
exact opposite of the strategy for the above case.
To distinguish between the two cases, BFQ uses an empirical burst-size
threshold, found through extensive tests and monitoring of daily
usage. Only large bursts, i.e., burst with a size above this
threshold, are considered as generated by a high number of parallel
processes. In this respect, upstart-based boot proved to be rather
hard to detect as generating a large burst of queue creations, because
with upstart most of the queues created in a burst exit *before* the
next queues in the same burst are created. To address this issue, I
changed the burst-detection mechanism so as to not decrease the size
of the current burst even if one of the queues in the burst is
eliminated.
Unfortunately, this missing decrease causes false positives on very
fast systems: on the start-up of a complex application, such as
libreoffice writer, so many queues are created, served and exited
shortly after each other, that a large burst of queue creations is
wrongly detected as occurring. These false positives just disappear if
the size of a burst is decreased when one of the queues in the burst
exits. This commit restores the missing burst-size decrease, relying
of the fact that upstart is apparently unlikely to be used on systems
running this and future versions of the kernel.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Mauro Andreolini <mauro.andreolini@unimore.it>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A just-created bfq_queue, say Q, may happen to be merged with another
bfq_queue on the very first invocation of the function
__bfq_insert_request. In such a case, even if Q would clearly deserve
interactive weight raising (as it has just been created), the function
bfq_add_request does not make it to be invoked for Q, and thus to
activate weight raising for Q. As a consequence, when the state of Q
is saved for a possible future restore, after a split of Q from the
other bfq_queue(s), such a state happens to be (unjustly)
non-weight-raised. Then the bfq_queue will not enjoy any weight
raising on the split, even if should still be in an interactive
weight-raising period when the split occurs.
This commit solves this problem as follows, for a just-created
bfq_queue that is being early-merged: it stores directly, in the saved
state of the bfq_queue, the weight-raising state that would have been
assigned to the bfq_queue if not early-merged.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As already explained in the message of commit "block, bfq: fix
wrong init of saved start time for weight raising", if a soft
real-time weight-raising period happens to be nested in a larger
interactive weight-raising period, then BFQ restores the interactive
weight raising at the end of the soft real-time weight raising. In
particular, BFQ checks whether the latter has ended only on request
dispatches.
Unfortunately, the above scheme fails to restore interactive weight
raising in the following corner case: if a bfq_queue, say Q,
1) Is merged with another bfq_queue while it is in a nested soft
real-time weight-raising period. The weight-raising state of Q is
then saved, and not considered any longer until a split occurs.
2) Is split from the other bfq_queue(s) at a time instant when its
soft real-time weight raising is already finished.
On the split, while resuming the previous, soft real-time
weight-raised state of the bfq_queue Q, BFQ checks whether the
current soft real-time weight-raising period is actually over. If so,
BFQ switches weight raising off for Q, *without* checking whether the
soft real-time period was actually nested in a non-yet-finished
interactive weight-raising period.
This commit addresses this issue by adding the above missing check in
bfq_queue splits, and restoring interactive weight raising if needed.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit fixes a bug that causes bfq to fail to guarantee a high
responsiveness on some drives, if there is heavy random read+write I/O
in the background. More precisely, such a failure allowed this bug to
be found [1], but the bug may well cause other yet unreported
anomalies.
BFQ raises the weight of the bfq_queues associated with soft real-time
applications, to privilege the I/O, and thus reduce latency, for these
applications. This mechanism is named soft-real-time weight raising in
BFQ. A soft real-time period may happen to be nested into an
interactive weight raising period, i.e., it may happen that, when a
bfq_queue switches to a soft real-time weight-raised state, the
bfq_queue is already being weight-raised because deemed interactive
too. In this case, BFQ saves in a special variable
wr_start_at_switch_to_srt, the time instant when the interactive
weight-raising period started for the bfq_queue, i.e., the time
instant when BFQ started to deem the bfq_queue interactive. This value
is then used to check whether the interactive weight-raising period
would still be in progress when the soft real-time weight-raising
period ends. If so, interactive weight raising is restored for the
bfq_queue. This restore is useful, in particular, because it prevents
bfq_queues from losing their interactive weight raising prematurely,
as a consequence of spurious, short-lived soft real-time
weight-raising periods caused by wrong detections as soft real-time.
If, instead, a bfq_queue switches to soft-real-time weight raising
while it *is not* already in an interactive weight-raising period,
then the variable wr_start_at_switch_to_srt has no meaning during the
following soft real-time weight-raising period. Unfortunately the
handling of this case is wrong in BFQ: not only the variable is not
flagged somehow as meaningless, but it is also set to the time when
the switch to soft real-time weight-raising occurs. This may cause an
interactive weight-raising period to be considered mistakenly as still
in progress, and thus a spurious interactive weight-raising period to
start for the bfq_queue, at the end of the soft-real-time
weight-raising period. In particular the spurious interactive
weight-raising period will be considered as still in progress, if the
soft-real-time weight-raising period does not last very long. The
bfq_queue will then be wrongly privileged and, if I/O bound, will
unjustly steal bandwidth to truly interactive or soft real-time
bfq_queues, harming responsiveness and low latency.
This commit fixes this issue by just setting wr_start_at_switch_to_srt
to minus infinity (farthest past time instant according to jiffies
macros): when the soft-real-time weight-raising period ends, certainly
no interactive weight-raising period will be considered as still in
progress.
[1] Background I/O Type: Random - Background I/O mix: Reads and writes
- Application to start: LibreOffice Writer in
http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.13-IO-Laptop
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Mirko Montanari <mirkomontanari91@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For some reason, the laptop mode IO completion notified was never wired
up for blk-mq. Ensure that we trigger the callback appropriately, to arm
the laptop mode flush timer.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We don't have any notion of a tagging cache anymore, and haven't
for a long time. Kill off the unused enums.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
since 9bddeb2a5b "blk-mq: make per-sw-queue bio merge as default .bio_merge"
there is no caller for this function.
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
part_stat_show takes a part device not a disk, so we should use
part_to_disk.
Fixes: d62e26b3ffd2("block: pass in queue to inflight accounting")
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The lockdep code had reported the following unsafe locking scenario:
CPU0 CPU1
---- ----
lock(s_active#228);
lock(&bdev->bd_mutex/1);
lock(s_active#228);
lock(&bdev->bd_mutex);
*** DEADLOCK ***
The deadlock may happen when one task (CPU1) is trying to delete a
partition in a block device and another task (CPU0) is accessing
tracing sysfs file (e.g. /sys/block/dm-1/trace/act_mask) in that
partition.
The s_active isn't an actual lock. It is a reference count (kn->count)
on the sysfs (kernfs) file. Removal of a sysfs file, however, require
a wait until all the references are gone. The reference count is
treated like a rwsem using lockdep instrumentation code.
The fact that a thread is in the sysfs callback method or in the
ioctl call means there is a reference to the opended sysfs or device
file. That should prevent the underlying block structure from being
removed.
Instead of using bd_mutex in the block_device structure, a new
blk_trace_mutex is now added to the request_queue structure to protect
access to the blk_trace structure.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fix typo in patch subject line, and prune a comment detailing how
the code used to work.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The job structure is allocated as part of the request, so we should not
free it in the error path of bsg_prepare_job.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A NULL pointer crash was reported for the case of having the BFQ IO
scheduler attached to the underlying blk-mq paths of a DM multipath
device. The crash occured in blk_mq_sched_insert_request()'s call to
e->type->ops.mq.insert_requests().
Paolo Valente correctly summarized why the crash occured with:
"the call chain (dm_mq_queue_rq -> map_request -> setup_clone ->
blk_rq_prep_clone) creates a cloned request without invoking
e->type->ops.mq.prepare_request for the target elevator e. The cloned
request is therefore not initialized for the scheduler, but it is
however inserted into the scheduler by blk_mq_sched_insert_request."
All said, a request-based DM multipath device's IO scheduler should be
the only one used -- when the original requests are issued to the
underlying paths as cloned requests they are inserted directly in the
underlying dispatch queue(s) rather than through an additional elevator.
But commit bd166ef18 ("blk-mq-sched: add framework for MQ capable IO
schedulers") switched blk_insert_cloned_request() from using
blk_mq_insert_request() to blk_mq_sched_insert_request(). Which
incorrectly added elevator machinery into a call chain that isn't
supposed to have any.
To fix this introduce a blk-mq private blk_mq_request_bypass_insert()
that blk_insert_cloned_request() calls to insert the request without
involving any elevator that may be attached to the cloned request's
request_queue.
Fixes: bd166ef183 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Cc: stable@vger.kernel.org
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix possible integer overflow in __blkdev_sectors_to_bio_pages if
sector_t is 32-bit.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 615d22a51c ("block: Fix __blkdev_issue_zeroout loop")
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Users who are booting off their Opal enabled drives are having
issues when they have a shadow MBR set up after s3/resume cycle.
When the Drive has a shadow MBR setup the MBRDone flag is set to
false upon power loss (S3/S4/S5). When the MBRDone flag is false
I/O to LBA 0 -> LBA_END_MBR are remapped to the shadow mbr
of the drive. If the drive contains useful data in the 0 -> end_mbr
range upon s3 resume the user can never get to that data as the
drive will keep remapping it to the MBR. To fix this when we unlock
on S3 resume, we need to tell the drive that we're done with the
shadow mbr (even though we didnt use it) by setting true to MBRDone.
This way the drive will stop the remapping and the user can access
their data.
Acked-by Jon Derrick: <jonathan.derrick@intel.com>
Signed-off-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull followup block layer updates from Jens Axboe:
"I ended up splitting the main pull request for this series into two,
mainly because of clashes between NVMe fixes that went into 4.13 after
the for-4.14 branches were split off. This pull request is mostly
NVMe, but not exclusively. In detail, it contains:
- Two pull request for NVMe changes from Christoph. Nothing new on
the feature front, basically just fixes all over the map for the
core bits, transport, rdma, etc.
- Series from Bart, cleaning up various bits in the BFQ scheduler.
- Series of bcache fixes, which has been lingering for a release or
two. Coly sent this in, but patches from various people in this
area.
- Set of patches for BFQ from Paolo himself, updating both
documentation and fixing some corner cases in performance.
- Series from Omar, attempting to now get the 4k loop support
correct. Our confidence level is higher this time.
- Series from Shaohua for loop as well, improving O_DIRECT
performance and fixing a use-after-free"
* 'for-4.14/block-postmerge' of git://git.kernel.dk/linux-block: (74 commits)
bcache: initialize dirty stripes in flash_dev_run()
loop: set physical block size to logical block size
bcache: fix bch_hprint crash and improve output
bcache: Update continue_at() documentation
bcache: silence static checker warning
bcache: fix for gc and write-back race
bcache: increase the number of open buckets
bcache: Correct return value for sysfs attach errors
bcache: correct cache_dirty_target in __update_writeback_rate()
bcache: gc does not work when triggering by manual command
bcache: Don't reinvent the wheel but use existing llist API
bcache: do not subtract sectors_to_gc for bypassed IO
bcache: fix sequential large write IO bypass
bcache: Fix leak of bdev reference
block/loop: remove unused field
block/loop: fix use after free
bfq: Use icq_to_bic() consistently
bfq: Suppress compiler warnings about comparisons
bfq: Check kstrtoul() return value
bfq: Declare local functions static
...
For the same reasons we already cache the leftmost pointer, apply the same
optimization for rb_last() calls. Users must explicitly do this as
rb_root_cached only deals with the smallest node.
[dave@stgolabs.net: brain fart #1]
Link: http://lkml.kernel.org/r/20170731155955.GD21328@linux-80c1.suse
Link: http://lkml.kernel.org/r/20170719014603.19029-18-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
... with the generic rbtree flavor instead. No changes
in semantics whatsoever.
Link: http://lkml.kernel.org/r/20170719014603.19029-11-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is mostly updates of the usual suspects: lpfc, qla2xxx, hisi_sas, megaraid_sas, zfcp and a host of minor updates.
The major driver change here is the elimination of the block based
cciss driver in favour of the SCSI based hpsa driver (which now drives
all the legacy cases cciss used to be required for). Plus a reset
handler clean up and the redo of the SAS SMP handler to use bsg lib.
Signed-off-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
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Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI updates from James Bottomley:
"This is mostly updates of the usual suspects: lpfc, qla2xxx, hisi_sas,
megaraid_sas, zfcp and a host of minor updates.
The major driver change here is the elimination of the block based
cciss driver in favour of the SCSI based hpsa driver (which now drives
all the legacy cases cciss used to be required for). Plus a reset
handler clean up and the redo of the SAS SMP handler to use bsg lib"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (279 commits)
scsi: scsi-mq: Always unprepare before requeuing a request
scsi: Show .retries and .jiffies_at_alloc in debugfs
scsi: Improve requeuing behavior
scsi: Call scsi_initialize_rq() for filesystem requests
scsi: qla2xxx: Reset the logo flag, after target re-login.
scsi: qla2xxx: Fix slow mem alloc behind lock
scsi: qla2xxx: Clear fc4f_nvme flag
scsi: qla2xxx: add missing includes for qla_isr
scsi: qla2xxx: Fix an integer overflow in sysfs code
scsi: aacraid: report -ENOMEM to upper layer from aac_convert_sgraw2()
scsi: aacraid: get rid of one level of indentation
scsi: aacraid: fix indentation errors
scsi: storvsc: fix memory leak on ring buffer busy
scsi: scsi_transport_sas: switch to bsg-lib for SMP passthrough
scsi: smartpqi: remove the smp_handler stub
scsi: hpsa: remove the smp_handler stub
scsi: bsg-lib: pass the release callback through bsg_setup_queue
scsi: Rework handling of scsi_device.vpd_pg8[03]
scsi: Rework the code for caching Vital Product Data (VPD)
scsi: rcu: Introduce rcu_swap_protected()
...
Pull MD updates from Shaohua Li:
"This update mainly fixes bugs:
- Make raid5 ppl support several ppl from Pawel
- Several raid5-cache bug fixes from Song
- Bitmap fixes from Neil and Me
- One raid1/10 regression fix since 4.12 from Me
- Other small fixes and cleanup"
* tag 'md/4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
md/bitmap: disable bitmap_resize for file-backed bitmaps.
raid5-ppl: Recovery support for multiple partial parity logs
md: Runtime support for multiple ppls
md/raid0: attach correct cgroup info in bio
lib/raid6: align AVX512 constants to 512 bits, not bytes
raid5: remove raid5_build_block
md/r5cache: call mddev_lock/unlock() in r5c_journal_mode_show
md: replace seq_release_private with seq_release
md: notify about new spare disk in the container
md/raid1/10: reset bio allocated from mempool
md/raid5: release/flush io in raid5_do_work()
md/bitmap: copy correct data for bitmap super
Pull block layer updates from Jens Axboe:
"This is the first pull request for 4.14, containing most of the code
changes. It's a quiet series this round, which I think we needed after
the churn of the last few series. This contains:
- Fix for a registration race in loop, from Anton Volkov.
- Overflow complaint fix from Arnd for DAC960.
- Series of drbd changes from the usual suspects.
- Conversion of the stec/skd driver to blk-mq. From Bart.
- A few BFQ improvements/fixes from Paolo.
- CFQ improvement from Ritesh, allowing idling for group idle.
- A few fixes found by Dan's smatch, courtesy of Dan.
- A warning fixup for a race between changing the IO scheduler and
device remova. From David Jeffery.
- A few nbd fixes from Josef.
- Support for cgroup info in blktrace, from Shaohua.
- Also from Shaohua, new features in the null_blk driver to allow it
to actually hold data, among other things.
- Various corner cases and error handling fixes from Weiping Zhang.
- Improvements to the IO stats tracking for blk-mq from me. Can
drastically improve performance for fast devices and/or big
machines.
- Series from Christoph removing bi_bdev as being needed for IO
submission, in preparation for nvme multipathing code.
- Series from Bart, including various cleanups and fixes for switch
fall through case complaints"
* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
kernfs: checking for IS_ERR() instead of NULL
drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
drbd: Fix allyesconfig build, fix recent commit
drbd: switch from kmalloc() to kmalloc_array()
drbd: abort drbd_start_resync if there is no connection
drbd: move global variables to drbd namespace and make some static
drbd: rename "usermode_helper" to "drbd_usermode_helper"
drbd: fix race between handshake and admin disconnect/down
drbd: fix potential deadlock when trying to detach during handshake
drbd: A single dot should be put into a sequence.
drbd: fix rmmod cleanup, remove _all_ debugfs entries
drbd: Use setup_timer() instead of init_timer() to simplify the code.
drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
drbd: new disk-option disable-write-same
drbd: Fix resource role for newly created resources in events2
drbd: mark symbols static where possible
drbd: Send P_NEG_ACK upon write error in protocol != C
drbd: add explicit plugging when submitting batches
drbd: change list_for_each_safe to while(list_first_entry_or_null)
drbd: introduce drbd_recv_header_maybe_unplug
...
Here is the big char/misc driver update for 4.14-rc1.
Lots of different stuff in here, it's been an active development cycle
for some reason. Highlights are:
- updated binder driver, this brings binder up to date with what
shipped in the Android O release, plus some more changes that
happened since then that are in the Android development trees.
- coresight updates and fixes
- mux driver file renames to be a bit "nicer"
- intel_th driver updates
- normal set of hyper-v updates and changes
- small fpga subsystem and driver updates
- lots of const code changes all over the driver trees
- extcon driver updates
- fmc driver subsystem upadates
- w1 subsystem minor reworks and new features and drivers added
- spmi driver updates
Plus a smattering of other minor driver updates and fixes.
All of these have been in linux-next with no reported issues for a
while.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here is the big char/misc driver update for 4.14-rc1.
Lots of different stuff in here, it's been an active development cycle
for some reason. Highlights are:
- updated binder driver, this brings binder up to date with what
shipped in the Android O release, plus some more changes that
happened since then that are in the Android development trees.
- coresight updates and fixes
- mux driver file renames to be a bit "nicer"
- intel_th driver updates
- normal set of hyper-v updates and changes
- small fpga subsystem and driver updates
- lots of const code changes all over the driver trees
- extcon driver updates
- fmc driver subsystem upadates
- w1 subsystem minor reworks and new features and drivers added
- spmi driver updates
Plus a smattering of other minor driver updates and fixes.
All of these have been in linux-next with no reported issues for a
while"
* tag 'char-misc-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (244 commits)
ANDROID: binder: don't queue async transactions to thread.
ANDROID: binder: don't enqueue death notifications to thread todo.
ANDROID: binder: Don't BUG_ON(!spin_is_locked()).
ANDROID: binder: Add BINDER_GET_NODE_DEBUG_INFO ioctl
ANDROID: binder: push new transactions to waiting threads.
ANDROID: binder: remove proc waitqueue
android: binder: Add page usage in binder stats
android: binder: fixup crash introduced by moving buffer hdr
drivers: w1: add hwmon temp support for w1_therm
drivers: w1: refactor w1_slave_show to make the temp reading functionality separate
drivers: w1: add hwmon support structures
eeprom: idt_89hpesx: Support both ACPI and OF probing
mcb: Fix an error handling path in 'chameleon_parse_cells()'
MCB: add support for SC31 to mcb-lpc
mux: make device_type const
char: virtio: constify attribute_group structures.
Documentation/ABI: document the nvmem sysfs files
lkdtm: fix spelling mistake: "incremeted" -> "incremented"
perf: cs-etm: Fix ETMv4 CONFIGR entry in perf.data file
nvmem: include linux/err.h from header
...
- Lots of hfi1 driver updates (mixed with a few qib and core updates as
well)
- rxe updates
- various mlx updates
- Set default roce type to RoCEv2
- Several larger fixes for bnxt_re that were too big for -rc
- Several larger fixes for qedr that, likewise, were too big for -rc
- Misc core changes
- Make the hns_roce driver compilable on arches other than aarch64 so we
can more easily debug build issues related to it
- Add rdma-netlink infrastructure updates
- Add automatic IRQ affinity infrastructure
- Add 32bit lid support
- Lots of misc fixes across the subsystem from random people
- Autoloading of RDMA netlink modules
- PCI pool cleanups from Romain Perier
- mlx5 driver feature additions and fixes
- Hardware tag matchine feature
- Fix sleeping in atomic when resolving roce ah
- Add experimental ioctl interface as posted to linux-api@
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Merge tag 'for-linus-ioctl' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma
Pull rdma updates from Doug Ledford:
"This is a big pull request.
Of note is that I'm sending you the new ioctl API for the rdma
subsystem. We put it up on linux-api@, but didn't get much response.
The API is complex, but it solves two different problems in one go:
1) The bi-directional nature of the RDMA file write calls, which
created the security hole we had to handle (and for which the fix
is now causing problems for systems in production, we were a bit
over zealous in the fix and the ability to open a device, then
fork, then create new queue pairs on the device and use them is
broken).
2) The bloat caused by different vendors implementing extensions to
the base verbs API. Each vendor's hardware is slightly different,
and the hardware might be suitable for one extension but not
another.
By the time we add generic extensions for all the different ways
that the different hardware can offload things, the API becomes
bloated. Things like our completion structs have started to exceed
a cache line in size because of all the elements needed to support
this. That in turn shows up heavily in the performance graphs with
a noticable drop in performance on 100Gigabit links as our
completion structs go from occupying one cache line to 1+.
This API makes things like the completion structs modular in a
very similar way to netlink so that your structs can only include
the items needed for the offloads/features you are actually using
on a given queue pair. In that way we support everything, but only
use what we need, and our structs stay smaller.
The ioctl API is better explained by the posting on linux-api@ than I
can explain it here, so I'll just leave it at that.
The rest of the pull request is typical stuff.
Updates for 4.14 kernel merge window
- Lots of hfi1 driver updates (mixed with a few qib and core updates
as well)
- rxe updates
- various mlx updates
- Set default roce type to RoCEv2
- Several larger fixes for bnxt_re that were too big for -rc
- Several larger fixes for qedr that, likewise, were too big for -rc
- Misc core changes
- Make the hns_roce driver compilable on arches other than aarch64 so
we can more easily debug build issues related to it
- Add rdma-netlink infrastructure updates
- Add automatic IRQ affinity infrastructure
- Add 32bit lid support
- Lots of misc fixes across the subsystem from random people
- Autoloading of RDMA netlink modules
- PCI pool cleanups from Romain Perier
- mlx5 driver feature additions and fixes
- Hardware tag matchine feature
- Fix sleeping in atomic when resolving roce ah
- Add experimental ioctl interface as posted to linux-api@"
* tag 'for-linus-ioctl' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (328 commits)
IB/core: Expose ioctl interface through experimental Kconfig
IB/core: Assign root to all drivers
IB/core: Add completion queue (cq) object actions
IB/core: Add legacy driver's user-data
IB/core: Export ioctl enum types to user-space
IB/core: Explicitly destroy an object while keeping uobject
IB/core: Add macros for declaring methods and attributes
IB/core: Add uverbs merge trees functionality
IB/core: Add DEVICE object and root tree structure
IB/core: Declare an object instead of declaring only type attributes
IB/core: Add new ioctl interface
RDMA/vmw_pvrdma: Fix a signedness
RDMA/vmw_pvrdma: Report network header type in WC
IB/core: Add might_sleep() annotation to ib_init_ah_from_wc()
IB/cm: Fix sleeping in atomic when RoCE is used
IB/core: Add support to finalize objects in one transaction
IB/core: Add a generic way to execute an operation on a uobject
Documentation: Hardware tag matching
IB/mlx5: Support IB_SRQT_TM
net/mlx5: Add XRQ support
...
Some code uses icq_to_bic() to convert an io_cq pointer to a
bfq_io_cq pointer while other code uses a direct cast. Convert
the code that uses a direct cast such that it uses icq_to_bic().
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch avoids that the following warnings are reported when
building with W=1:
block/bfq-iosched.c: In function 'bfq_back_seek_max_store':
block/bfq-iosched.c:4860:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
if (__data < (MIN)) \
^
block/bfq-iosched.c:4876:1: note: in expansion of macro 'STORE_FUNCTION'
STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
^~~~~~~~~~~~~~
block/bfq-iosched.c: In function 'bfq_slice_idle_store':
block/bfq-iosched.c:4860:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
if (__data < (MIN)) \
^
block/bfq-iosched.c:4879:1: note: in expansion of macro 'STORE_FUNCTION'
STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
^~~~~~~~~~~~~~
block/bfq-iosched.c: In function 'bfq_slice_idle_us_store':
block/bfq-iosched.c:4892:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
if (__data < (MIN)) \
^
block/bfq-iosched.c:4899:1: note: in expansion of macro 'USEC_STORE_FUNCTION'
USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
^~~~~~~~~~~~~~~~~~~
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make sysfs writes fail for invalid numbers instead of storing
uninitialized data copied from the stack. This patch removes
all uninitialized_var() occurrences from the BFQ source code.
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This patch avoids that gcc 7 issues a warning about fall-through
when building with W=1.
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the function bfq_update_next_in_service is invoked as a consequence
of the activation or requeueing of an entity, say E, then it doesn't
invoke bfq_lookup_next_entity to get the next-in-service entity. In
contrast, it follows a shorter path: if E happens to be eligible (see
commit "bfq-sq-mq: make lookup_next_entity push up vtime on
expirations" for details on eligibility) and to have a lower virtual
finish time than the current candidate as next-in-service entity, then
E directly becomes the next-in-service entity. Unfortunately, there is
a corner case for which this shorter path makes
bfq_update_next_in_service choose a non eligible entity: it occurs if
both E and the current next-in-service entity happen to be non
eligible when bfq_update_next_in_service is invoked. In this case, E
is not set as next-in-service, and, since bfq_lookup_next_entity is
not invoked, the state of the parent entity is not updated so as to
end up with an eligible entity as the proper next-in-service entity.
In this respect, next-in-service is actually allowed to be non
eligible while some queue is in service: since no system-virtual-time
push-up can be performed in that case (see again commit "bfq-sq-mq:
make lookup_next_entity push up vtime on expirations" for details),
next-in-service is chosen, speculatively, as a function of the
possible value that the system virtual time may get after a push
up. But the correctness of the schedule breaks if next-in-service is
still a non eligible entity when it is time to set in service the next
entity. Unfortunately, this may happen in the above corner case.
This commit fixes this problem by making bfq_update_next_in_service
invoke bfq_lookup_next_entity not only if the above shorter path
cannot be taken, but also if the shorter path is taken but fails to
yield an eligible next-in-service entity.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the function bfq_update_next_in_service is invoked as a consequence
of the activation or requeueing of an entity, say E, and finds out
that E belongs to a higher-priority class than that of the current
next-in-service entity, then it sets next_in_service directly to
E. But this may lead to anomalous schedules, because E may happen not
be eligible for service, because its virtual start time is higher than
the system virtual time for its service tree.
This commit addresses this issue by simply removing this direct
switch.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
To provide a very smooth service, bfq starts to serve a bfq_queue
only if the queue is 'eligible', i.e., if the same queue would
have started to be served in the ideal, perfectly fair system that
bfq simulates internally. This is obtained by associating each
queue with a virtual start time, and by computing a special system
virtual time quantity: a queue is eligible only if the system
virtual time has reached the virtual start time of the
queue. Finally, bfq guarantees that, when a new queue must be set
in service, there is always at least one eligible entity for each
active parent entity in the scheduler. To provide this guarantee,
the function __bfq_lookup_next_entity pushes up, for each parent
entity on which it is invoked, the system virtual time to the
minimum among the virtual start times of the entities in the
active tree for the parent entity (more precisely, the push up
occurs if the system virtual time happens to be lower than all
such virtual start times).
There is however a circumstance in which __bfq_lookup_next_entity
cannot push up the system virtual time for a parent entity, even
if the system virtual time is lower than the virtual start times
of all the child entities in the active tree. It happens if one of
the child entities is in service. In fact, in such a case, there
is already an eligible entity, the in-service one, even if it may
not be not present in the active tree (because in-service entities
may be removed from the active tree).
Unfortunately, in the last re-design of the
hierarchical-scheduling engine, the reset of the pointer to the
in-service entity for a given parent entity--reset to be done as a
consequence of the expiration of the in-service entity--always
happens after the function __bfq_lookup_next_entity has been
invoked. This causes the function to think that there is still an
entity in service for the parent entity, and then that the system
virtual time cannot be pushed up, even if actually such a
no-more-in-service entity has already been properly reinserted
into the active tree (or in some other tree if no more
active). Yet, the system virtual time *had* to be pushed up, to be
ready to correctly choose the next queue to serve. Because of the
lack of this push up, bfq may wrongly set in service a queue that
had been speculatively pre-computed as the possible
next-in-service queue, but that would no more be the one to serve
after the expiration and the reinsertion into the active trees of
the previously in-service entities.
This commit addresses this issue by making
__bfq_lookup_next_entity properly push up the system virtual time
if an expiration is occurring.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The SAS code will need it. Also mark the name argument const to match
bsg_register_queue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
The block core requests modules with the "-iosched" name suffix, but
mq-deadline does not have that suffix. Add an alias.
Fixes: 945ffb60c1 ("mq-deadline: add blk-mq adaptation of the deadline ...")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The block core requests modules with the "-iosched" name suffix, but
bfq no longer has that suffix. Add an alias.
Fixes: ea25da4808 ("block, bfq: split bfq-iosched.c into multiple ...")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The only caller of this function is blk_start_request() in the same
file. Fix blk_start_request() description accordingly.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
struct call_single_data is used in IPIs to transfer information between
CPUs. Its size is bigger than sizeof(unsigned long) and less than
cache line size. Currently it is not allocated with any explicit alignment
requirements. This makes it possible for allocated call_single_data to
cross two cache lines, which results in double the number of the cache lines
that need to be transferred among CPUs.
This can be fixed by requiring call_single_data to be aligned with the
size of call_single_data. Currently the size of call_single_data is the
power of 2. If we add new fields to call_single_data, we may need to
add padding to make sure the size of new definition is the power of 2
as well.
Fortunately, this is enforced by GCC, which will report bad sizes.
To set alignment requirements of call_single_data to the size of
call_single_data, a struct definition and a typedef is used.
To test the effect of the patch, I used the vm-scalability multiple
thread swap test case (swap-w-seq-mt). The test will create multiple
threads and each thread will eat memory until all RAM and part of swap
is used, so that huge number of IPIs are triggered when unmapping
memory. In the test, the throughput of memory writing improves ~5%
compared with misaligned call_single_data, because of faster IPIs.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Huang, Ying <ying.huang@intel.com>
[ Add call_single_data_t and align with size of call_single_data. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/87bmnqd6lz.fsf@yhuang-mobile.sh.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is a race between changing I/O elevator and request_queue removal
which can trigger the warning in kobject_add_internal. A program can
use sysfs to request a change of elevator at the same time another task
is unregistering the request_queue the elevator would be attached to.
The elevator's kobject will then attempt to be connected to the
request_queue in the object tree when the request_queue has just been
removed from sysfs. This triggers the warning in kobject_add_internal
as the request_queue no longer has a sysfs directory:
kobject_add_internal failed for iosched (error: -2 parent: queue)
------------[ cut here ]------------
WARNING: CPU: 3 PID: 14075 at lib/kobject.c:244 kobject_add_internal+0x103/0x2d0
To fix this warning, we can check the QUEUE_FLAG_REGISTERED flag when
changing the elevator and use the request_queue's sysfs_lock to
serialize between clearing the flag and the elevator testing the flag.
Signed-off-by: David Jeffery <djeffery@redhat.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The last parameter "count" never be used in xxx_var_store,
convert these functions to void.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Normally I wouldn't bother with this, but in my opinion the comments are
the most important part of this whole file since without them no one
would have any clue how this insanity works.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The symbolic constants QUEUE_FLAG_SCSI_PASSTHROUGH, QUEUE_FLAG_QUIESCED
and REQ_NOWAIT are missing from blk-mq-debugfs.c. Add these to
blk-mq-debugfs.c such that these appear as names in debugfs instead of
as numbers.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
put_device(pdev) will call pdev->type->release finally, and blk_free_devt
has been called in part_release(), so remove it.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since we split the scsi_request out of struct request bsg fails to
provide a reply-buffer for the drivers. This was done via the pointer
for sense-data, that is not preallocated anymore.
Failing to allocate/assign it results in illegal dereferences because
LLDs use this pointer unquestioned.
An example panic on s390x, using the zFCP driver, looks like this (I had
debugging on, otherwise NULL-pointer dereferences wouldn't even panic on
s390x):
Unable to handle kernel pointer dereference in virtual kernel address space
Failing address: 6b6b6b6b6b6b6000 TEID: 6b6b6b6b6b6b6403
Fault in home space mode while using kernel ASCE.
AS:0000000001590007 R3:0000000000000024
Oops: 0038 ilc:2 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in: <Long List>
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.12.0-bsg-regression+ #3
Hardware name: IBM 2964 N96 702 (z/VM 6.4.0)
task: 0000000065cb0100 task.stack: 0000000065cb4000
Krnl PSW : 0704e00180000000 000003ff801e4156 (zfcp_fc_ct_els_job_handler+0x16/0x58 [zfcp])
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
Krnl GPRS: 0000000000000001 000000005fa9d0d0 000000005fa9d078 0000000000e16866
000003ff00000290 6b6b6b6b6b6b6b6b 0000000059f78f00 000000000000000f
00000000593a0958 00000000593a0958 0000000060d88800 000000005ddd4c38
0000000058b50100 07000000659cba08 000003ff801e8556 00000000659cb9a8
Krnl Code: 000003ff801e4146: e31020500004 lg %r1,80(%r2)
000003ff801e414c: 58402040 l %r4,64(%r2)
#000003ff801e4150: e35020200004 lg %r5,32(%r2)
>000003ff801e4156: 50405004 st %r4,4(%r5)
000003ff801e415a: e54c50080000 mvhi 8(%r5),0
000003ff801e4160: e33010280012 lt %r3,40(%r1)
000003ff801e4166: a718fffb lhi %r1,-5
000003ff801e416a: 1803 lr %r0,%r3
Call Trace:
([<000003ff801e8556>] zfcp_fsf_req_complete+0x726/0x768 [zfcp])
[<000003ff801ea82a>] zfcp_fsf_reqid_check+0x102/0x180 [zfcp]
[<000003ff801eb980>] zfcp_qdio_int_resp+0x230/0x278 [zfcp]
[<00000000009b91b6>] qdio_kick_handler+0x2ae/0x2c8
[<00000000009b9e3e>] __tiqdio_inbound_processing+0x406/0xc10
[<00000000001684c2>] tasklet_action+0x15a/0x1d8
[<0000000000bd28ec>] __do_softirq+0x3ec/0x848
[<00000000001675a4>] irq_exit+0x74/0xf8
[<000000000010dd6a>] do_IRQ+0xba/0xf0
[<0000000000bd19e8>] io_int_handler+0x104/0x2d4
[<00000000001033b6>] enabled_wait+0xb6/0x188
([<000000000010339e>] enabled_wait+0x9e/0x188)
[<000000000010396a>] arch_cpu_idle+0x32/0x50
[<0000000000bd0112>] default_idle_call+0x52/0x68
[<00000000001cd0fa>] do_idle+0x102/0x188
[<00000000001cd41e>] cpu_startup_entry+0x3e/0x48
[<0000000000118c64>] smp_start_secondary+0x11c/0x130
[<0000000000bd2016>] restart_int_handler+0x62/0x78
[<0000000000000000>] (null)
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<000003ff801e41d6>] zfcp_fc_ct_job_handler+0x3e/0x48 [zfcp]
Kernel panic - not syncing: Fatal exception in interrupt
This patch moves bsg-lib to allocate and setup struct bsg_job ahead of
time, including the allocation of a buffer for the reply-data.
This means, struct bsg_job is not allocated separately anymore, but as part
of struct request allocation - similar to struct scsi_cmd. Reflect this in
the function names that used to handle creation/destruction of struct
bsg_job.
Reported-by: Steffen Maier <maier@linux.vnet.ibm.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Fixes: 82ed4db499 ("block: split scsi_request out of struct request")
Cc: <stable@vger.kernel.org> #4.11+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In dm-integrity target we register integrity profile that have
both generate_fn and verify_fn callbacks set to NULL.
This is used if dm-integrity is stacked under a dm-crypt device
for authenticated encryption (integrity payload contains authentication
tag and IV seed).
In this case the verification is done through own crypto API
processing inside dm-crypt; integrity profile is only holder
of these data. (And memory is owned by dm-crypt as well.)
After the commit (and previous changes)
Commit 7c20f11680
Author: Christoph Hellwig <hch@lst.de>
Date: Mon Jul 3 16:58:43 2017 -0600
bio-integrity: stop abusing bi_end_io
we get this crash:
: BUG: unable to handle kernel NULL pointer dereference at (null)
: IP: (null)
: *pde = 00000000
...
:
: Workqueue: kintegrityd bio_integrity_verify_fn
: task: f48ae180 task.stack: f4b5c000
: EIP: (null)
: EFLAGS: 00210286 CPU: 0
: EAX: f4b5debc EBX: 00001000 ECX: 00000001 EDX: 00000000
: ESI: 00001000 EDI: ed25f000 EBP: f4b5dee8 ESP: f4b5dea4
: DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
: CR0: 80050033 CR2: 00000000 CR3: 32823000 CR4: 001406d0
: Call Trace:
: ? bio_integrity_process+0xe3/0x1e0
: bio_integrity_verify_fn+0xea/0x150
: process_one_work+0x1c7/0x5c0
: worker_thread+0x39/0x380
: kthread+0xd6/0x110
: ? process_one_work+0x5c0/0x5c0
: ? kthread_worker_fn+0x100/0x100
: ? kthread_worker_fn+0x100/0x100
: ret_from_fork+0x19/0x24
: Code: Bad EIP value.
: EIP: (null) SS:ESP: 0068:f4b5dea4
: CR2: 0000000000000000
Patch just skip the whole verify workqueue if verify_fn is set to NULL.
Fixes: 7c20f116 ("bio-integrity: stop abusing bi_end_io")
Signed-off-by: Milan Broz <gmazyland@gmail.com>
[hch: trivial whitespace fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
discard request usually is very big and easily use all bandwidth budget
of a cgroup. discard request size doesn't really mean the size of data
written, so it doesn't make sense to account it into bandwidth budget.
Jens pointed out treating the size 0 doesn't make sense too, because
discard request does have cost. But it's not easy to find the actual
cost. This patch simply makes the size one sector.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This way we don't need a block_device structure to submit I/O. The
block_device has different life time rules from the gendisk and
request_queue and is usually only available when the block device node
is open. Other callers need to explicitly create one (e.g. the lightnvm
passthrough code, or the new nvme multipathing code).
For the actual I/O path all that we need is the gendisk, which exists
once per block device. But given that the block layer also does
partition remapping we additionally need a partition index, which is
used for said remapping in generic_make_request.
Note that all the block drivers generally want request_queue or
sometimes the gendisk, so this removes a layer of indirection all
over the stack.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This helper allows looking up a partion under RCU protection without
grabbing a reference to it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The timeout handler set by blk_queue_rq_timed_out() is only used
in single queue mode. Calling this function for blk-mq drivers is
wrong. Hence issue a warning if this function is called by a blk-mq
driver.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Calling blk_start_queue() from interrupt context with the queue
lock held and without disabling IRQs, as the skd driver does, is
safe. This patch avoids that loading the skd driver triggers the
following warning:
WARNING: CPU: 11 PID: 1348 at block/blk-core.c:283 blk_start_queue+0x84/0xa0
RIP: 0010:blk_start_queue+0x84/0xa0
Call Trace:
skd_unquiesce_dev+0x12a/0x1d0 [skd]
skd_complete_internal+0x1e7/0x5a0 [skd]
skd_complete_other+0xc2/0xd0 [skd]
skd_isr_completion_posted.isra.30+0x2a5/0x470 [skd]
skd_isr+0x14f/0x180 [skd]
irq_forced_thread_fn+0x2a/0x70
irq_thread+0x144/0x1a0
kthread+0x125/0x140
ret_from_fork+0x2a/0x40
Fixes: commit a038e25364 ("[PATCH] blk_start_queue() must be called with irq disabled - add warning")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Annotate gendisk.part_tbl and disk_part_tbl.part dereferences with
rcu_dereference_protected(). This patch does not change the behavior
of the modified code but ensures that sparse does not complain about
disk->part_tbl manipulations nor about part_tbl->part accesses.
Additionally, improve documentation of the locking requirements of
the modified functions.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This was detected by sparse.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since blk_mq_ops.reinit_request is only called from inside
blk_mq_reinit_tagset(), make this function pointer an argument of
blk_mq_reinit_tagset() instead of a member of struct blk_mq_ops.
This patch does not change any functionality but makes
blk_mq_reinit_tagset() calls easier to read and to analyze.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: James Smart <james.smart@broadcom.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This function is only used inside the block layer core. Hence
unexport it.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since patch "blk-mq: switch .queue_rq return value to blk_status_t"
.queue_rq() returns a BLK_STS_* value instead of a BLK_MQ_RQ_*
value. Hence refer to the former in comments about .queue_rq()
return values.
Fixes: commit 39a70c76b8 ("blk-mq: clarify dispatch may not be drained/blocked by stopping queue")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
While pci_irq_get_affinity should never fail for SMP kernel that
implement the affinity mapping, it will always return NULL in the
UP case, so provide a fallback mapping of all queues to CPU 0 in
that case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_mq_get_request() does not release the callers queue usage counter
when allocation fails. The caller still needs to account for its own
queue usage when it is unable to allocate a request.
Fixes: 1ad43c0078 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
Reported-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In below scenario blkio cgroup does not work as per their assigned
weights :-
1. When the underlying device is nonrotational with a single HW queue
with depth of >= CFQ_HW_QUEUE_MIN
2. When the use case is forming two blkio cgroups cg1(weight 1000) &
cg2(wight 100) and two processes(file1 and file2) doing sync IO in
their respective blkio cgroups.
For above usecase result of fio (without this patch):-
file1: (groupid=0, jobs=1): err= 0: pid=685: Thu Jan 1 19:41:49 1970
write: IOPS=1315, BW=41.1MiB/s (43.1MB/s)(1024MiB/24906msec)
<...>
file2: (groupid=0, jobs=1): err= 0: pid=686: Thu Jan 1 19:41:49 1970
write: IOPS=1295, BW=40.5MiB/s (42.5MB/s)(1024MiB/25293msec)
<...>
// both the process BW is equal even though they belong to diff.
cgroups with weight of 1000(cg1) and 100(cg2)
In above case (for non rotational NCQ devices),
as soon as the request from cg1 is completed and even
though it is provided with higher set_slice=10, because of CFQ
algorithm when the driver tries to fetch the request, CFQ expires
this group without providing any idle time nor weight priority
and schedules another cfq group (in this case cg2).
And thus both cfq groups(cg1 & cg2) keep alternating to get the
disk time and hence loses the cgroup weight based scheduling.
Below patch gives a chance to cfq algorithm (cfq_arm_slice_timer)
to arm the slice timer in case group_idle is enabled.
In case if group_idle is also not required (including for nonrotational
NCQ drives), we need to explicitly set group_idle = 0 from sysfs for
such cases.
With this patch result of fio(for above usecase) :-
file1: (groupid=0, jobs=1): err= 0: pid=690: Thu Jan 1 00:06:08 1970
write: IOPS=1706, BW=53.3MiB/s (55.9MB/s)(1024MiB/19197msec)
<..>
file2: (groupid=0, jobs=1): err= 0: pid=691: Thu Jan 1 00:06:08 1970
write: IOPS=1043, BW=32.6MiB/s (34.2MB/s)(1024MiB/31401msec)
<..>
// In this processes BW is as per their respective cgroups weight.
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When a queue associated with a process remains empty, there are cases
where throughput gets boosted if the device is idled to await the
arrival of a new I/O request for that queue. Currently, BFQ assumes
that one of these cases is when the device has no internal queueing
(regardless of the properties of the I/O being served). Unfortunately,
this condition has proved to be too general. So, this commit refines it
as "the device has no internal queueing and is rotational".
This refinement provides a significant throughput boost with random
I/O, on flash-based storage without internal queueing. For example, on
a HiKey board, throughput increases by up to 125%, growing, e.g., from
6.9MB/s to 15.6MB/s with two or three random readers in parallel.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The logic that decides whether to idle the device is scattered across
three functions. Almost all of the logic is in the function
bfq_bfqq_may_idle, but (1) part of the decision is made in
bfq_update_idle_window, and (2) the function bfq_bfqq_must_idle may
switch off idling regardless of the output of bfq_bfqq_may_idle. In
addition, both bfq_update_idle_window and bfq_bfqq_must_idle make
their decisions as a function of parameters that are used, for similar
purposes, also in bfq_bfqq_may_idle. This commit addresses these
issues by moving all the logic into bfq_bfqq_may_idle.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We haven't used these in years, but somehow the definitions still
remained. Kill them, and renumber the QUEUE_FLAG_ space. We had
a hole in the beginning of the space, too.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The blk_mq_delay_kick_requeue_list() function is used by the device
mapper and only by the device mapper to rerun the queue and requeue
list after a delay. This function is called once per request that
gets requeued. Modify this function such that the queue is run once
per path change event instead of once per request that is requeued.
Fixes: commit 2849450ad3 ("blk-mq: introduce blk_mq_delay_kick_requeue_list()")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This gets us back to the behavior in 4.12 and earlier.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 7c20f116 ("bio-integrity: stop abusing bi_end_io")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In dm-integrity target we register integrity profile that have
both generate_fn and verify_fn callbacks set to NULL.
This is used if dm-integrity is stacked under a dm-crypt device
for authenticated encryption (integrity payload contains authentication
tag and IV seed).
In this case the verification is done through own crypto API
processing inside dm-crypt; integrity profile is only holder
of these data. (And memory is owned by dm-crypt as well.)
After the commit (and previous changes)
Commit 7c20f11680
Author: Christoph Hellwig <hch@lst.de>
Date: Mon Jul 3 16:58:43 2017 -0600
bio-integrity: stop abusing bi_end_io
we get this crash:
: BUG: unable to handle kernel NULL pointer dereference at (null)
: IP: (null)
: *pde = 00000000
...
:
: Workqueue: kintegrityd bio_integrity_verify_fn
: task: f48ae180 task.stack: f4b5c000
: EIP: (null)
: EFLAGS: 00210286 CPU: 0
: EAX: f4b5debc EBX: 00001000 ECX: 00000001 EDX: 00000000
: ESI: 00001000 EDI: ed25f000 EBP: f4b5dee8 ESP: f4b5dea4
: DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
: CR0: 80050033 CR2: 00000000 CR3: 32823000 CR4: 001406d0
: Call Trace:
: ? bio_integrity_process+0xe3/0x1e0
: bio_integrity_verify_fn+0xea/0x150
: process_one_work+0x1c7/0x5c0
: worker_thread+0x39/0x380
: kthread+0xd6/0x110
: ? process_one_work+0x5c0/0x5c0
: ? kthread_worker_fn+0x100/0x100
: ? kthread_worker_fn+0x100/0x100
: ret_from_fork+0x19/0x24
: Code: Bad EIP value.
: EIP: (null) SS:ESP: 0068:f4b5dea4
: CR2: 0000000000000000
Patch just skip the whole verify workqueue if verify_fn is set to NULL.
Fixes: 7c20f116 ("bio-integrity: stop abusing bi_end_io")
Signed-off-by: Milan Broz <gmazyland@gmail.com>
[hch: trivial whitespace fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Modify blk_mq_in_flight() to count both a partition and root at
the same time. Then we only have to call it once, instead of
potentially looping the tags twice.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We don't have to inc/dec some counter, since we can just
iterate the tags. That makes inc/dec a noop, but means we
have to iterate busy tags to get an in-flight count.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Instead of returning the count that matches the partition, pass
in an array of two ints. Index 0 will be filled with the inflight
count for the partition in question, and index 1 will filled
with the root inflight count, if the partition passed in is not the
root.
This is in preparation for being able to calculate both in one
go.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
No functional change in this patch, just in preparation for
basing the inflight mechanism on the queue in question.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since we introduced blk-mq-sched, the tags->rqs[] array has been
dynamically assigned. So we need to check for NULL when iterating,
since there's a window of time where the bit is set, but we haven't
dynamically assigned the tags->rqs[] array position yet.
This is perfectly safe, since the memory backing of the request is
never going away while the device is alive.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This makes the code more obvious, and moves the most likely branch first
in the function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Like pci and virtio, we add a rdma helper for affinity
spreading. This achieves optimal mq affinity assignments
according to the underlying rdma device affinity maps.
Reviewed-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>
submit_bio_wait() does not consume bio reference. Add comment about
that.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When blk_mq_get_request() failed, preempt counter isn't
released, and blk_mq_make_request() doesn't release the counter
too.
This patch fixes the issue, and makes sure that preempt counter
is only held if rq is allocated successfully. The same policy is
applied on .q_usage_counter too.
Signed-off-by: Ming Lei <minlei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We recently had a bug in the IPR SCSI driver, where it would end up
making the SCSI mid layer run the mq hardware queue with interrupts
disabled. This isn't legal, since the software queue locking relies
on never being grabbed from interrupt context. Additionally, drivers
that set BLK_MQ_F_BLOCKING may schedule from this context.
Add a WARN_ON_ONCE() to catch bad users up front.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Groups of BFQ queues are represented by generic entities in BFQ. When
a queue belonging to a parent entity is deactivated, the parent entity
may need to be deactivated too, in case the deactivated queue was the
only active queue for the parent entity. This deactivation may need to
be propagated upwards if the entity belongs, in its turn, to a further
higher-level entity, and so on. In particular, the upward propagation
of deactivation stops at the first parent entity that remains active
even if one of its child entities has been deactivated.
To decide whether the last non-deactivation condition holds for a
parent entity, BFQ checks whether the field next_in_service is still
not NULL for the parent entity, after the deactivation of one of its
child entity. If it is not NULL, then there are certainly other active
entities in the parent entity, and deactivations can stop.
Unfortunately, this check misses a corner case: if in_service_entity
is not NULL, then next_in_service may happen to be NULL, although the
parent entity is evidently active. This happens if: 1) the entity
pointed by in_service_entity is the only active entity in the parent
entity, and 2) according to the definition of next_in_service, the
in_service_entity cannot be considered as next_in_service. See the
comments on the definition of next_in_service for details on this
second point.
Hitting the above corner case causes crashes.
To address this issue, this commit:
1) Extends the above check on only next_in_service to controlling both
next_in_service and in_service_entity (if any of them is not NULL,
then no further deactivation is performed)
2) Improves the (important) comments on how next_in_service is defined
and updated; in particular it fixes a few rather obscure paragraphs
Reported-by: Eric Wheeler <bfq-sched@lists.ewheeler.net>
Reported-by: Rick Yiu <rick_yiu@htc.com>
Reported-by: Tom X Nguyen <tom81094@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Eric Wheeler <bfq-sched@lists.ewheeler.net>
Tested-by: Rick Yiu <rick_yiu@htc.com>
Tested-by: Laurentiu Nicola <lnicola@dend.ro>
Tested-by: Tom X Nguyen <tom81094@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
BFQ implements hierarchical scheduling by representing each group of
queues with a generic parent entity. For each parent entity, BFQ
maintains an in_service_entity pointer: if one of the child entities
happens to be in service, in_service_entity points to it. The
resetting of these pointers happens only on queue expirations: when
the in-service queue is expired, i.e., stops to be the queue in
service, BFQ resets all in_service_entity pointers along the
parent-entity path from this queue to the root entity.
Functions handling the scheduling of entities assume, naturally, that
in-service entities are active, i.e., have pending I/O requests (or,
as a special case, even if they have no pending requests, they are
expected to receive a new request very soon, with the scheduler idling
the storage device while waiting for such an event). Unfortunately,
the above resetting scheme of the in_service_entity pointers may cause
this assumption to be violated. For example, the in-service queue may
happen to remain without requests because of a request merge. In this
case the queue does become idle, and all related data structures are
updated accordingly. But in_service_entity still points to the queue
in the parent entity. This inconsistency may even propagate to
higher-level parent entities, if they happen to become idle as well,
as a consequence of the leaf queue becoming idle. For this queue and
parent entities, scheduling functions have an undefined behaviour,
and, as reported, may easily lead to kernel crashes or hangs.
This commit addresses this issue by simply resetting the
in_service_entity field also when it is detected to point to an entity
becoming idle (regardless of why the entity becomes idle).
Reported-by: Laurentiu Nicola <lnicola@dend.ro>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Laurentiu Nicola <lnicola@dend.ro>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently cfq/bfq/blk-throttle output cgroup info in trace in their own
way. Now we have standard blktrace API for this, so convert them to use
it.
Note, this changes the behavior a little bit. cgroup info isn't output
by default, we only do this with 'blk_cgroup' option enabled. cgroup
info isn't output as a string by default too, we only do this with
'blk_cgname' option enabled. Also cgroup info is output in different
position of the note string. I think these behavior changes aren't a big
issue (actually we make trace data shorter which is good), since the
blktrace note is solely for debugging.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkcg_bio_issue_check() already gets blkcg for a BIO.
bio_associate_blkcg() uses a percpu refcounter, so it's a very cheap
operation. There is no point we don't attach the cgroup info into bio at
blkcg_bio_issue_check. This also makes blktrace outputs correct cgroup
info.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already do this for PCI mappings, and the higher level code now
expects that CPU on/offlining doesn't have an affect on the queue
mappings.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The blk-mq code lacks support for looking at the rpm_status field, tracking
active requests and the RQF_PM flag.
Due to the default switch to blk-mq for scsi people start to run into
suspend / resume issue due to this fact, so make sure we disable the runtime
PM functionality until it is properly implemented.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
