Currently block plug holds up to 16 non-mergeable requests. This makes
sense if the request size is small, eg, reduce lock contention. But if
request size is big enough, we don't need to worry about lock
contention. Holding such request makes no sense and it lows the disk
utilization.
In practice, this improves 10% throughput for my raid5 sequential write
workload.
The size (128k) is arbitrary right now, but it makes sure lock
contention is small. This probably could be more intelligent, eg, check
average request size holded. Since this is mainly for sequential IO,
probably not worthy.
V2: check the last request instead of the first request, so as long as
there is one big size request we flush the plug.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
bsg_validate_sgv4_hdr() doesn't care about the request_queue, so drop it
from it's arguments.
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls
are followed by kicking the requeue list. Hence add an argument to
these two functions that allows to kick the requeue list. This was
proposed by Christoph Hellwig.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
blk_mq_quiesce_queue() waits until ongoing .queue_rq() invocations
have finished. This function does *not* wait until all outstanding
requests have finished (this means invocation of request.end_io()).
The algorithm used by blk_mq_quiesce_queue() is as follows:
* Hold either an RCU read lock or an SRCU read lock around
.queue_rq() calls. The former is used if .queue_rq() does not
block and the latter if .queue_rq() may block.
* blk_mq_quiesce_queue() first calls blk_mq_stop_hw_queues()
followed by synchronize_srcu() or synchronize_rcu(). The latter
call waits for .queue_rq() invocations that started before
blk_mq_quiesce_queue() was called.
* The blk_mq_hctx_stopped() calls that control whether or not
.queue_rq() will be called are called with the (S)RCU read lock
held. This is necessary to avoid race conditions against
blk_mq_quiesce_queue().
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Since blk_mq_requeue_work() no longer restarts stopped queues
canceling requeue work is no longer needed to prevent that a
stopped queue would be restarted. Hence remove this function.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Since blk_mq_requeue_work() starts stopped queues and since
execution of this function can be scheduled after a queue has
been stopped it is not possible to stop queues without using
an additional state variable to track whether or not the queue
has been stopped. Hence modify blk_mq_requeue_work() such that it
does not start stopped queues. My conclusion after a review of
the blk_mq_stop_hw_queues() and blk_mq_{delay_,}kick_requeue_list()
callers is as follows:
* In the dm driver starting and stopping queues should only happen
if __dm_suspend() or __dm_resume() is called and not if the
requeue list is processed.
* In the SCSI core queue stopping and starting should only be
performed by the scsi_internal_device_block() and
scsi_internal_device_unblock() functions but not by any other
function. Although the blk_mq_stop_hw_queue() call in
scsi_queue_rq() may help to reduce CPU load if a LLD queue is
full, figuring out whether or not a queue should be restarted
when requeueing a command would require to introduce additional
locking in scsi_mq_requeue_cmd() to avoid a race with
scsi_internal_device_block(). Avoid this complexity by removing
the blk_mq_stop_hw_queue() call from scsi_queue_rq().
* In the NVMe core only the functions that call
blk_mq_start_stopped_hw_queues() explicitly should start stopped
queues.
* A blk_mq_start_stopped_hwqueues() call must be added in the
xen-blkfront driver in its blkif_recover() function.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Roger Pau Monné <roger.pau@citrix.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: James Bottomley <jejb@linux.vnet.ibm.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Move the "hctx stopped" test and the insert request calls into
blk_mq_direct_issue_request(). Rename that function into
blk_mq_try_issue_directly() to reflect its new semantics. Pass
the hctx pointer to that function instead of looking it up a
second time. These changes avoid that code has to be duplicated
in the next patch.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
The function blk_queue_stopped() allows to test whether or not a
traditional request queue has been stopped. Introduce a helper
function that allows block drivers to query easily whether or not
one or more hardware contexts of a blk-mq queue have been stopped.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Multiple functions test the BLK_MQ_S_STOPPED bit so introduce
a helper function that performs this test.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
The meaning of the BLK_MQ_S_STOPPED flag is "do not call
.queue_rq()". Hence modify blk_mq_make_request() such that requests
are queued instead of issued if a queue has been stopped.
Reported-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
This is a helper that pins down a range from an iov_iter and adds it to
a bio without requiring a separate memory allocation for the page array.
It will be used for upcoming direct I/O implementations for block devices
and iomap based file systems.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[hch: ported to the iov_iter interface, renamed and added comments.
All blame should be directed to me and all fame should go to Kent
after this!]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Remove the WRITE_* and READ_SYNC wrappers, and just use the flags
directly. Where applicable this also drops usage of the
bio_set_op_attrs wrapper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Noidle should be the default for writes as seen by all the compounds
definitions in fs.h using it. In fact only direct I/O really should
be using NODILE, so turn the whole flag around to get the defaults
right, which will make our life much easier especially onces the
WRITE_* defines go away.
This assumes all the existing "raw" users of REQ_SYNC for writes
want noidle behavior, which seems to be spot on from a quick audit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Now that we don't need the common flags to overflow outside the range
of a 32-bit type we can encode them the same way for both the bio and
request fields. This in addition allows us to place the operation
first (and make some room for more ops while we're at it) and to
stop having to shift around the operation values.
In addition this allows passing around only one value in the block layer
instead of two (and eventuall also in the file systems, but we can do
that later) and thus clean up a lot of code.
Last but not least this allows decreasing the size of the cmd_flags
field in struct request to 32-bits. Various functions passing this
value could also be updated, but I'd like to avoid the churn for now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
A lot of the REQ_* flags are only used on struct requests, and only of
use to the block layer and a few drivers that dig into struct request
internals.
This patch adds a new req_flags_t rq_flags field to struct request for
them, and thus dramatically shrinks the number of common requests. It
also removes the unfortunate situation where we have to fit the fields
from the same enum into 32 bits for struct bio and 64 bits for
struct request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
It's the last bio-only REQ_* flag, and we have space for it in the bio
bi_flags field.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
With the addition of the zoned operations the tests in this function
became incorrect. But I think it's much better to just open code the
allow operations in the only caller anyway.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
We can just use struct blk_mq_alloc_data - it has a few more
members, but we allocate it further down the stack anyway. So
this cleans up the code, and reduces the stack overhead a bit.
Signed-off-by: Jens Axboe <axboe@fb.com>
If we end up sleeping due to running out of requests, we should
update the hardware and software queues in the map ctx structure.
Otherwise we could end up having rq->mq_ctx point to the pre-sleep
context, and risk corrupting ctx->rq_list since we'll be
grabbing the wrong lock when inserting the request.
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Chris Mason <clm@fb.com>
Fixes: 63581af3f3 ("blk-mq: remove non-blocking pass in blk_mq_map_request")
Signed-off-by: Jens Axboe <axboe@fb.com>
If we end up sleeping due to running out of requests, we should
update the hardware and software queues in the map ctx structure.
Otherwise we could end up having rq->mq_ctx point to the pre-sleep
context, and risk corrupting ctx->rq_list since we'll be
grabbing the wrong lock when inserting the request.
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Chris Mason <clm@fb.com>
Fixes: 63581af3f3 ("blk-mq: remove non-blocking pass in blk_mq_map_request")
Signed-off-by: Jens Axboe <axboe@fb.com>
This patch fixes one issue reported by Kent, which can
be triggered in bcachefs over sata disk. Actually it
is a generic issue in block flush vs. blk-tag.
Cc: Christoph Hellwig <hch@infradead.org>
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The blkdev_report_zones produces a harmless warning when
-Wmaybe-uninitialized is set, after gcc gets a little confused
about the multiple 'goto' here:
block/blk-zoned.c: In function 'blkdev_report_zones':
block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Moving the assignment to nr_zones makes this a little simpler
while also avoiding the warning reliably. I'm removing the
extraneous initialization of 'int ret' in the same patch, as
that is semi-related and could cause an uninitialized use of
that variable to not produce a warning.
Fixes: 6a0cb1bc10 ("block: Implement support for zoned block devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
When bandblocks_set acknowledges a range or badblocks_clear a range,
it's possible all badblocks are acknowledged. We should update
unacked_exist if this occurs.
Signed-off-by: Shaohua Li <shli@fb.com>
Reviewed-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Tested-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Pull block fixes from Jens Axboe:
"A set of fixes that missed the merge window, mostly due to me being
away around that time.
Nothing major here, a mix of nvme cleanups and fixes, and one fix for
the badblocks handling"
* 'for-linus' of git://git.kernel.dk/linux-block:
nvmet: use symbolic constants for CNS values
nvme: use symbolic constants for CNS values
nvme.h: add an enum for cns values
nvme.h: don't use uuid_be
nvme.h: resync with nvme-cli
nvme: Add tertiary number to NVME_VS
nvme : Add sysfs entry for NVMe CMBs when appropriate
nvme: don't schedule multiple resets
nvme: Delete created IO queues on reset
nvme: Stop probing a removed device
badblocks: fix overlapping check for clearing
Patch adds an association between iocontext ioprio and the ioprio of a
request. This is done to enable request based drivers the ability to
act on priority information stored in the request. An example being
ATA devices that support command priorities. If the ATA driver discovers
that the device supports command priorities and the request has valid
priority information indicating the request is high priority, then a high
priority command can be sent to the device. This should improve tail
latencies for high priority IO on any device that queues requests
internally and can make use of the priority information stored in the
request.
The ioprio of the request is set in blk_rq_set_prio which takes the
request and the ioc as arguments. If the ioc is valid in blk_rq_set_prio
then the iopriority of the request is set as the iopriority of the ioc.
In init_request_from_bio a check is made to see if the ioprio of the bio
is valid and if so then the request prio comes from the bio.
Signed-off-by: Adam Manzananares <adam.manzanares@wdc.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Adds the new BLKREPORTZONE and BLKRESETZONE ioctls for respectively
obtaining the zone configuration of a zoned block device and resetting
the write pointer of sequential zones of a zoned block device.
The BLKREPORTZONE ioctl maps directly to a single call of the function
blkdev_report_zones. The zone information result is passed as an array
of struct blk_zone identical to the structure used internally for
processing the REQ_OP_ZONE_REPORT operation. The BLKRESETZONE ioctl
maps to a single call of the blkdev_reset_zones function.
Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Implement zoned block device zone information reporting and reset.
Zone information are reported as struct blk_zone. This implementation
does not differentiate between host-aware and host-managed device
models and is valid for both. Two functions are provided:
blkdev_report_zones for discovering the zone configuration of a
zoned block device, and blkdev_reset_zones for resetting the write
pointer of sequential zones. The helper function blk_queue_zone_size
and bdev_zone_size are also provided for, as the name suggest,
obtaining the zone size (in 512B sectors) of the zones of the device.
Signed-off-by: Hannes Reinecke <hare@suse.de>
[Damien: * Removed the zone cache
* Implement report zones operation based on earlier proposal
by Shaun Tancheff <shaun.tancheff@seagate.com>]
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Define REQ_OP_ZONE_REPORT and REQ_OP_ZONE_RESET for handling zones of
host-managed and host-aware zoned block devices. With with these two
new operations, the total number of operations defined reaches 8 and
still fits with the 3 bits definition of REQ_OP_BITS.
Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The queue limits already have a 'chunk_sectors' setting, so
we should be presenting it via sysfs.
Signed-off-by: Hannes Reinecke <hare@suse.de>
[Damien: Updated Documentation/ABI/testing/sysfs-block]
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Add the zoned queue limit to indicate the zoning model of a block device.
Defined values are 0 (BLK_ZONED_NONE) for regular block devices,
1 (BLK_ZONED_HA) for host-aware zone block devices and 2 (BLK_ZONED_HM)
for host-managed zone block devices. The standards defined drive managed
model is not defined here since these block devices do not provide any
command for accessing zone information. Drive managed model devices will
be reported as BLK_ZONED_NONE.
The helper functions blk_queue_zoned_model and bdev_zoned_model return
the zoned limit and the functions blk_queue_is_zoned and bdev_is_zoned
return a boolean for callers to test if a block device is zoned.
The zoned attribute is also exported as a string to applications via
sysfs. BLK_ZONED_NONE shows as "none", BLK_ZONED_HA as "host-aware" and
BLK_ZONED_HM as "host-managed".
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.
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Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugins update from Kees Cook:
"This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot
time as possible, hoping to capitalize on any possible variation in
CPU operation (due to runtime data differences, hardware differences,
SMP ordering, thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example
for how to manipulate kernel code using the gcc plugin internals"
* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
latent_entropy: Mark functions with __latent_entropy
gcc-plugins: Add latent_entropy plugin
Pull cgroup updates from Tejun Heo:
- tracepoints for basic cgroup management operations added
- kernfs and cgroup path formatting functions updated to behave in the
style of strlcpy()
- non-critical bug fixes
* 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL
cgroup: fix error handling regressions in proc_cgroup_show() and cgroup_release_agent()
cpuset: fix error handling regression in proc_cpuset_show()
cgroup: add tracepoints for basic operations
cgroup: make cgroup_path() and friends behave in the style of strlcpy()
kernfs: remove kernfs_path_len()
kernfs: make kernfs_path*() behave in the style of strlcpy()
kernfs: add dummy implementation of kernfs_path_from_node()
Current bad block clear implementation assumes the range to clear
overlaps with at least one bad block already stored. If given range to
clear precedes first bad block in a list, the first entry is incorrectly
updated.
Check not only if stored block end is past clear block end but also if
stored block start is before clear block end.
Signed-off-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Make sure that the offset and length arguments that we're using to
construct WRITE SAME and DISCARD requests are actually aligned to the
logical block size. Failure to do this causes other errors in other parts
of the block layer or the SCSI layer because disks don't support partial
logical block writes.
Link: http://lkml.kernel.org/r/147518379026.22791.4437508871355153928.stgit@birch.djwong.org
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Mike Snitzer <snitzer@redhat.com> # tweaked header
Cc: Brian Foster <bfoster@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "fallocate for block devices", v11.
This is a patchset to fix page cache coherency with BLKZEROOUT and
implement fallocate for block devices.
The first patch is a fix to the existing BLKZEROOUT ioctl to invalidate
the page cache if the zeroing command to the underlying device succeeds.
Without this patch we still have the pagecache coherence bug that's been
in the kernel forever.
The second patch changes the internal block device functions to reject
attempts to discard or zeroout that are not aligned to the logical block
size. Previously, we only checked that the start/len parameters were
512-byte aligned, which caused kernel BUG_ONs for unaligned IOs to 4k-LBA
devices.
The third patch creates an fallocate handler for block devices, wires up
the FALLOC_FL_PUNCH_HOLE flag to zeroing-discard, and connects
FALLOC_FL_ZERO_RANGE to write-same so that we can have a consistent
fallocate interface between files and block devices. It also allows the
combination of PUNCH_HOLE and NO_HIDE_STALE to invoke non-zeroing discard.
Test cases for the new block device fallocate are now in xfstests as
generic/349-351.
This patch (of 3):
Invalidate the page cache (as a regular O_DIRECT write would do) to avoid
returning stale cache contents at a later time.
Link: http://lkml.kernel.org/r/147518378313.22791.16649519283678515021.stgit@birch.djwong.org
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The __latent_entropy gcc attribute can be used only on functions and
variables. If it is on a function then the plugin will instrument it for
gathering control-flow entropy. If the attribute is on a variable then
the plugin will initialize it with random contents. The variable must
be an integer, an integer array type or a structure with integer fields.
These specific functions have been selected because they are init
functions (to help gather boot-time entropy), are called at unpredictable
times, or they have variable loops, each of which provide some level of
latent entropy.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
Pull blk-mq CPU hotplug update from Jens Axboe:
"This is the conversion of blk-mq to the new hotplug state machine"
* 'for-4.9/block-smp' of git://git.kernel.dk/linux-block:
blk-mq: fixup "Convert to new hotplug state machine"
blk-mq: Convert to new hotplug state machine
blk-mq/cpu-notif: Convert to new hotplug state machine
Pull blk-mq irq/cpu mapping updates from Jens Axboe:
"This is the block-irq topic branch for 4.9-rc. It's mostly from
Christoph, and it allows drivers to specify their own mappings, and
more importantly, to share the blk-mq mappings with the IRQ affinity
mappings. It's a good step towards making this work better out of the
box"
* 'for-4.9/block-irq' of git://git.kernel.dk/linux-block:
blk_mq: linux/blk-mq.h does not include all the headers it depends on
blk-mq: kill unused blk_mq_create_mq_map()
blk-mq: get rid of the cpumask in struct blk_mq_tags
nvme: remove the post_scan callout
nvme: switch to use pci_alloc_irq_vectors
blk-mq: provide a default queue mapping for PCI device
blk-mq: allow the driver to pass in a queue mapping
blk-mq: remove ->map_queue
blk-mq: only allocate a single mq_map per tag_set
blk-mq: don't redistribute hardware queues on a CPU hotplug event
Pull block layer updates from Jens Axboe:
"This is the main pull request for block layer changes in 4.9.
As mentioned at the last merge window, I've changed things up and now
do just one branch for core block layer changes, and driver changes.
This avoids dependencies between the two branches. Outside of this
main pull request, there are two topical branches coming as well.
This pull request contains:
- A set of fixes, and a conversion to blk-mq, of nbd. From Josef.
- Set of fixes and updates for lightnvm from Matias, Simon, and Arnd.
Followup dependency fix from Geert.
- General fixes from Bart, Baoyou, Guoqing, and Linus W.
- CFQ async write starvation fix from Glauber.
- Add supprot for delayed kick of the requeue list, from Mike.
- Pull out the scalable bitmap code from blk-mq-tag.c and make it
generally available under the name of sbitmap. Only blk-mq-tag uses
it for now, but the blk-mq scheduling bits will use it as well.
From Omar.
- bdev thaw error progagation from Pierre.
- Improve the blk polling statistics, and allow the user to clear
them. From Stephen.
- Set of minor cleanups from Christoph in block/blk-mq.
- Set of cleanups and optimizations from me for block/blk-mq.
- Various nvme/nvmet/nvmeof fixes from the various folks"
* 'for-4.9/block' of git://git.kernel.dk/linux-block: (54 commits)
fs/block_dev.c: return the right error in thaw_bdev()
nvme: Pass pointers, not dma addresses, to nvme_get/set_features()
nvme/scsi: Remove power management support
nvmet: Make dsm number of ranges zero based
nvmet: Use direct IO for writes
admin-cmd: Added smart-log command support.
nvme-fabrics: Add host_traddr options field to host infrastructure
nvme-fabrics: revise host transport option descriptions
nvme-fabrics: rework nvmf_get_address() for variable options
nbd: use BLK_MQ_F_BLOCKING
blkcg: Annotate blkg_hint correctly
cfq: fix starvation of asynchronous writes
blk-mq: add flag for drivers wanting blocking ->queue_rq()
blk-mq: remove non-blocking pass in blk_mq_map_request
blk-mq: get rid of manual run of queue with __blk_mq_run_hw_queue()
block: export bio_free_pages to other modules
lightnvm: propagate device_add() error code
lightnvm: expose device geometry through sysfs
lightnvm: control life of nvm_dev in driver
blk-mq: register device instead of disk
...
Pull CPU hotplug updates from Thomas Gleixner:
"Yet another batch of cpu hotplug core updates and conversions:
- Provide core infrastructure for multi instance drivers so the
drivers do not have to keep custom lists.
- Convert custom lists to the new infrastructure. The block-mq custom
list conversion comes through the block tree and makes the diffstat
tip over to more lines removed than added.
- Handle unbalanced hotplug enable/disable calls more gracefully.
- Remove the obsolete CPU_STARTING/DYING notifier support.
- Convert another batch of notifier users.
The relayfs changes which conflicted with the conversion have been
shipped to me by Andrew.
The remaining lot is targeted for 4.10 so that we finally can remove
the rest of the notifiers"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
cpufreq: Fix up conversion to hotplug state machine
blk/mq: Reserve hotplug states for block multiqueue
x86/apic/uv: Convert to hotplug state machine
s390/mm/pfault: Convert to hotplug state machine
mips/loongson/smp: Convert to hotplug state machine
mips/octeon/smp: Convert to hotplug state machine
fault-injection/cpu: Convert to hotplug state machine
padata: Convert to hotplug state machine
cpufreq: Convert to hotplug state machine
ACPI/processor: Convert to hotplug state machine
virtio scsi: Convert to hotplug state machine
oprofile/timer: Convert to hotplug state machine
block/softirq: Convert to hotplug state machine
lib/irq_poll: Convert to hotplug state machine
x86/microcode: Convert to hotplug state machine
sh/SH-X3 SMP: Convert to hotplug state machine
ia64/mca: Convert to hotplug state machine
ARM/OMAP/wakeupgen: Convert to hotplug state machine
ARM/shmobile: Convert to hotplug state machine
arm64/FP/SIMD: Convert to hotplug state machine
...
Unlocking a mutex twice is wrong. Hence modify blkcg_policy_register()
such that blkcg_pol_mutex is unlocked once if cpd == NULL. This patch
avoids that smatch reports the following error:
block/blk-cgroup.c:1378: blkcg_policy_register() error: double unlock 'mutex:&blkcg_pol_mutex'
Fixes: 06b285bd11 ("blkcg: fix blkcg_policy_data allocation bug")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Tejun Heo <tj@kernel.org>
This provides the caller a feedback that a given hctx is not mapped and thus
no command can be sent on it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
While debugging timeouts happening in my application workload (ScyllaDB), I have
observed calls to open() taking a long time, ranging everywhere from 2 seconds -
the first ones that are enough to time out my application - to more than 30
seconds.
The problem seems to happen because XFS may block on pending metadata updates
under certain circumnstances, and that's confirmed with the following backtrace
taken by the offcputime tool (iovisor/bcc):
ffffffffb90c57b1 finish_task_switch
ffffffffb97dffb5 schedule
ffffffffb97e310c schedule_timeout
ffffffffb97e1f12 __down
ffffffffb90ea821 down
ffffffffc046a9dc xfs_buf_lock
ffffffffc046abfb _xfs_buf_find
ffffffffc046ae4a xfs_buf_get_map
ffffffffc046babd xfs_buf_read_map
ffffffffc0499931 xfs_trans_read_buf_map
ffffffffc044a561 xfs_da_read_buf
ffffffffc0451390 xfs_dir3_leaf_read.constprop.16
ffffffffc0452b90 xfs_dir2_leaf_lookup_int
ffffffffc0452e0f xfs_dir2_leaf_lookup
ffffffffc044d9d3 xfs_dir_lookup
ffffffffc047d1d9 xfs_lookup
ffffffffc0479e53 xfs_vn_lookup
ffffffffb925347a path_openat
ffffffffb9254a71 do_filp_open
ffffffffb9242a94 do_sys_open
ffffffffb9242b9e sys_open
ffffffffb97e42b2 entry_SYSCALL_64_fastpath
00007fb0698162ed [unknown]
Inspecting my run with blktrace, I can see that the xfsaild kthread exhibit very
high "Dispatch wait" times, on the dozens of seconds range and consistent with
the open() times I have saw in that run.
Still from the blktrace output, we can after searching a bit, identify the
request that wasn't dispatched:
8,0 11 152 81.092472813 804 A WM 141698288 + 8 <- (8,1) 141696240
8,0 11 153 81.092472889 804 Q WM 141698288 + 8 [xfsaild/sda1]
8,0 11 154 81.092473207 804 G WM 141698288 + 8 [xfsaild/sda1]
8,0 11 206 81.092496118 804 I WM 141698288 + 8 ( 22911) [xfsaild/sda1]
<==== 'I' means Inserted (into the IO scheduler) ===================================>
8,0 0 289372 96.718761435 0 D WM 141698288 + 8 (15626265317) [swapper/0]
<==== Only 15s later the CFQ scheduler dispatches the request ======================>
As we can see above, in this particular example CFQ took 15 seconds to dispatch
this request. Going back to the full trace, we can see that the xfsaild queue
had plenty of opportunity to run, and it was selected as the active queue many
times. It would just always be preempted by something else (example):
8,0 1 0 81.117912979 0 m N cfq1618SN / insert_request
8,0 1 0 81.117913419 0 m N cfq1618SN / add_to_rr
8,0 1 0 81.117914044 0 m N cfq1618SN / preempt
8,0 1 0 81.117914398 0 m N cfq767A / slice expired t=1
8,0 1 0 81.117914755 0 m N cfq767A / resid=40
8,0 1 0 81.117915340 0 m N / served: vt=1948520448 min_vt=1948520448
8,0 1 0 81.117915858 0 m N cfq767A / sl_used=1 disp=0 charge=0 iops=1 sect=0
where cfq767 is the xfsaild queue and cfq1618 corresponds to one of the ScyllaDB
IO dispatchers.
The requests preempting the xfsaild queue are synchronous requests. That's a
characteristic of ScyllaDB workloads, as we only ever issue O_DIRECT requests.
While it can be argued that preempting ASYNC requests in favor of SYNC is part
of the CFQ logic, I don't believe that doing so for 15+ seconds is anyone's
goal.
Moreover, unless I am misunderstanding something, that breaks the expectation
set by the "fifo_expire_async" tunable, which in my system is set to the
default.
Looking at the code, it seems to me that the issue is that after we make
an async queue active, there is no guarantee that it will execute any request.
When the queue itself tests if it cfq_may_dispatch() it can bail if it sees SYNC
requests in flight. An incoming request from another queue can also preempt it
in such situation before we have the chance to execute anything (as seen in the
trace above).
This patch sets the must_dispatch flag if we notice that we have requests
that are already fifo_expired. This flag is always cleared after
cfq_dispatch_request() returns from cfq_dispatch_requests(), so it won't pin
the queue for subsequent requests (unless they are themselves expired)
Care is taken during preempt to still allow rt requests to preempt us
regardless.
Testing my workload with this patch applied produces much better results.
From the application side I see no timeouts, and the open() latency histogram
generated by systemtap looks much better, with the worst outlier at 131ms:
Latency histogram of xfs_buf_lock acquisition (microseconds):
value |-------------------------------------------------- count
0 | 11
1 |@@@@ 161
2 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1966
4 |@ 54
8 | 36
16 | 7
32 | 0
64 | 0
~
1024 | 0
2048 | 0
4096 | 1
8192 | 1
16384 | 2
32768 | 0
65536 | 0
131072 | 1
262144 | 0
524288 | 0
Signed-off-by: Glauber Costa <glauber@scylladb.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: linux-block@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The "blk_mq_queue_reinit_dead()" just cleared the cpumask instead doing
a copy. Since we might never had an online callback we could end up with
a ZERO mask which in turn leads to crash as test robot demonstarted.
Fixes: 65d5291eee ("blk-mq: Convert to new hotplug state machine")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
If a driver sets BLK_MQ_F_BLOCKING, it is allowed to block in its
->queue_rq() handler. For that case, blk-mq ensures that we always
calls it from a safe context.
Signed-off-by: Jens Axboe <axboe@fb.com>
Tested-by: Josef Bacik <jbacik@fb.com>
bt_get already does a non-blocking pass as well as running the queue
when scheduling internally, no need to duplicate it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Two cases:
1) blk_mq_alloc_request() needlessly re-runs the queue, after
calling into the tag allocation without NOWAIT set. We don't
need to do that.
2) blk_mq_map_request() should just use blk_mq_run_hw_queue() with
the async flag set to false.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Install the callbacks via the state machine so we can phase out the cpu
hotplug notifiers mess.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
Link: http://lkml.kernel.org/r/20160919212601.180033814@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Replace the block-mq notifier list management with the multi instance
facility in the cpu hotplug state machine.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
bio_free_pages is introduced in commit 1dfa0f68c0
("block: add a helper to free bio bounce buffer pages"),
we can reuse the func in other modules after it was
imported.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Enable devices without a gendisk instance to register itself with blk-mq
and expose the associated multi-queue sysfs entries.
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
Right now, if slice is expired, we start a new slice. If a bio is
queued, we keep on extending slice by throtle_slice interval (100ms).
This worked well as long as pending timer function got executed with-in
few milli seconds of scheduled time. But looks like with recent changes
in timer subsystem, slack can be much longer depending on the expiry time
of the scheduled timer.
commit 500462a9de ("timers: Switch to a non-cascading wheel")
This means, by the time timer function gets executed, it is possible the
delay from scheduled time is more than 100ms. That means current code
will conclude that existing slice has expired and a new one needs to
be started. New slice will be 100ms by default and that will not be
sufficient to meet rate requirement of group given the bio size and
bio will not be dispatched and we will start a new timer function to
wait. And when that timer expires, same process will repeat and we
will wait again and this can easily be an infinite loop.
Solve this issue by starting a new slice only if throttle gropup is
empty. If it is not empty, that means there should be an active slice
going on. Ideally it should not be expired but given the slack, it is
possible that it has expired.
Reported-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
and building block/blk-mq-pci.o should depend on CONFIG_BLOCK
Fixes: 973c4e372c ("blk-mq: provide a default queue mapping for PCI device")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
In order to get good cache behavior from a sbitmap, we want each CPU to
stick to its own cacheline(s) as much as possible. This might happen
naturally as the bitmap gets filled up and the alloc_hint values spread
out, but we really want this behavior from the start. blk-mq apparently
intended to do this, but the code to do this was never wired up. Get rid
of the dead code and make it part of the sbitmap library.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Again, there's no point in passing this in every time. Make it part of
struct sbitmap_queue and clean up the API.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Allocating your own per-cpu allocation hint separately makes for an
awkward API. Instead, allocate the per-cpu hint as part of the struct
sbitmap_queue. There's no point for a struct sbitmap_queue without the
cache, but you can still use a bare struct sbitmap.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This is a generally useful data structure, so make it available to
anyone else who might want to use it. It's also a nice cleanup
separating the allocation logic from the rest of the tag handling logic.
The code is behind a new Kconfig option, CONFIG_SBITMAP, which is only
selected by CONFIG_BLOCK for now.
This should be a complete noop functionality-wise.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
We currently account a '0' dispatch, and anything above that still falls
below the range set by BLK_MQ_MAX_DISPATCH_ORDER. If we dispatch more,
we don't account it.
Change the last bucket to be inclusive of anything above the range we
track, and have the sysfs file reflect that by including a '+' in the
output:
$ cat /sys/block/nvme0n1/mq/0/dispatched
0 1006
1 20229
2 1
4 0
8 0
16 0
32+ 0
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Unused now that NVMe sets up irq affinity before calling into blk-mq.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This allows drivers specify their own queue mapping by overriding the
setup-time function that builds the mq_map. This can be used for
example to build the map based on the MSI-X vector mapping provided
by the core interrupt layer for PCI devices.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
All drivers use the default, so provide an inline version of it. If we
ever need other queue mapping we can add an optional method back,
although supporting will also require major changes to the queue setup
code.
This provides better code generation, and better debugability as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The mapping is identical for all queues in a tag_set, so stop wasting
memory for building multiple. Note that for now I've kept the mq_map
pointer in the request_queue, but we'll need to investigate if we can
remove it without suffering too much from the additional pointer chasing.
The same would apply to the mq_ops pointer as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Currently blk-mq will totally remap hardware context when a CPU hotplug
even happened, which causes major havoc for drivers, as they are never
told about this remapping. E.g. any carefully sorted out CPU affinity
will just be completely messed up.
The rebuild also doesn't really help for the common case of cpu
hotplug, which is soft onlining / offlining of cpus - in this case we
should just leave the queue and irq mapping as is. If it actually
worked it would have helped in the case of physical cpu hotplug,
although for that we'd need a way to actually notify the driver.
Note that drivers may already be able to accommodate such a topology
change on their own, e.g. using the reset_controller sysfs file in NVMe
will cause the driver to get things right for this case.
With the rebuild removed we will simplify retain the queue mapping for
a soft offlined CPU that will work when it comes back online, and will
map any newly onlined CPU to queue 0 until the driver initiates
a rebuild of the queue map.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
blk_mq_delay_kick_requeue_list() provides the ability to kick the
q->requeue_list after a specified time. To do this the request_queue's
'requeue_work' member was changed to a delayed_work.
blk_mq_delay_kick_requeue_list() allows DM to defer processing requeued
requests while it doesn't make sense to immediately requeue them
(e.g. when all paths in a DM multipath have failed).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
commit e1defc4ff0
"block: Do away with the notion of hardsect_size"
removed the notion of "hardware sector size" from
the kernel in favor of logical block size, but
references remain in comments and documentation.
Update the remaining sites mentioning hardsect.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Allow the io_poll statistics to be zeroed to make for easier logging
of polling event.
Signed-off-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
In order to help determine the effectiveness of polling in a running
system it is usful to determine the ratio of how often the poll
function is called vs how often the completion is checked. For this
reason we add a poll_considered variable and add it to the sysfs entry
for io_poll.
Signed-off-by: Stephen Bates <sbates@raithlin.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
When drivers or the core calls this function, they usually
dereference the request shortly there after. Prefetch the first
cache line.
Profiling IO workloads shows that this is the most common cache
miss on the block side of things.
Signed-off-by: Jens Axboe <axboe@fb.com>
__blk_mq_run_hw_queue() currently warns if we are running the queue on a
CPU that isn't set in its mask. However, this can happen if a CPU is
being offlined, and the workqueue handling will place the work on CPU0
instead. Improve the warning so that it only triggers if the batch cpu
in the hardware queue is currently online. If it triggers for that
case, then it's indicative of a flow problem in blk-mq, so we want to
retain it for that case.
Signed-off-by: Jens Axboe <axboe@fb.com>
We do this in a few places, if the CPU is offline. This isn't allowed,
though, since on multi queue hardware, we can't just move a request
from one software queue to another, if they map to different hardware
queues. The request and tag isn't valid on another hardware queue.
This can happen if plugging races with CPU offlining. But it does
no harm, since it can only happen in the window where we are
currently busy freezing the queue and flushing IO, in preparation
for redoing the software <-> hardware queue mappings.
Signed-off-by: Jens Axboe <axboe@fb.com>
After arbitrary bio size was introduced, the incoming bio may
be very big. We have to split the bio into small bios so that
each holds at most BIO_MAX_PAGES bvecs for safety reason, such
as bio_clone().
This patch fixes the following kernel crash:
> [ 172.660142] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
> [ 172.660229] IP: [<ffffffff811e53b4>] bio_trim+0xf/0x2a
> [ 172.660289] PGD 7faf3e067 PUD 7f9279067 PMD 0
> [ 172.660399] Oops: 0000 [#1] SMP
> [...]
> [ 172.664780] Call Trace:
> [ 172.664813] [<ffffffffa007f3be>] ? raid1_make_request+0x2e8/0xad7 [raid1]
> [ 172.664846] [<ffffffff811f07da>] ? blk_queue_split+0x377/0x3d4
> [ 172.664880] [<ffffffffa005fb5f>] ? md_make_request+0xf6/0x1e9 [md_mod]
> [ 172.664912] [<ffffffff811eb860>] ? generic_make_request+0xb5/0x155
> [ 172.664947] [<ffffffffa0445c89>] ? prio_io+0x85/0x95 [bcache]
> [ 172.664981] [<ffffffffa0448252>] ? register_cache_set+0x355/0x8d0 [bcache]
> [ 172.665016] [<ffffffffa04497d3>] ? register_bcache+0x1006/0x1174 [bcache]
The issue can be reproduced by the following steps:
- create one raid1 over two virtio-blk
- build bcache device over the above raid1 and another cache device
and bucket size is set as 2Mbytes
- set cache mode as writeback
- run random write over ext4 on the bcache device
Fixes: 54efd50(block: make generic_make_request handle arbitrarily sized bios)
Reported-by: Sebastian Roesner <sroesner-kernelorg@roesner-online.de>
Reported-by: Eric Wheeler <bcache@lists.ewheeler.net>
Cc: stable@vger.kernel.org (4.3+)
Cc: Shaohua Li <shli@fb.com>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
blk_set_queue_dying() can be called while another thread is
submitting I/O or changing queue flags, e.g. through dm_stop_queue().
Hence protect the QUEUE_FLAG_DYING flag change with locking.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Commit 288dab8a35 ("block: add a separate operation type for secure
erase") split REQ_OP_SECURE_ERASE from REQ_OP_DISCARD without considering
all the places REQ_OP_DISCARD was being used to mean either. Fix those.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: 288dab8a35 ("block: add a separate operation type for secure erase")
Signed-off-by: Jens Axboe <axboe@fb.com>
Since commit 63a4cc2486, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.
No intended functional changes in this commit.
Signed-off-by: Jens Axboe <axboe@fb.com>
If we fail registering any of the hardware queues, we call
into blk_mq_unregister_disk() with the hotplug mutex already
held. Since blk_mq_unregister_disk() attempts to acquire the
same mutex, we end up in a less than happy place.
Reported-by: Jinpu Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The name for a bdi of a gendisk is derived from the gendisk's devt.
However, since the gendisk is destroyed before the bdi it leaves a
window where a new gendisk could dynamically reuse the same devt while a
bdi with the same name is still live. Arrange for the bdi to hold a
reference against its "owner" disk device while it is registered.
Otherwise we can hit sysfs duplicate name collisions like the following:
WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1'
Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015
0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec
ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351
0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8
Call Trace:
[<ffffffff8134caec>] dump_stack+0x63/0x87
[<ffffffff8108c351>] __warn+0xd1/0xf0
[<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80
[<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80
[<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90
[<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320
[<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0
[<ffffffff8134ff55>] kobject_add+0x75/0xd0
[<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f
[<ffffffff8148b0a5>] device_add+0x125/0x610
[<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100
[<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20
[<ffffffff811b775c>] bdi_register+0x8c/0x180
[<ffffffff811b7877>] bdi_register_dev+0x27/0x30
[<ffffffff813317f5>] add_disk+0x175/0x4a0
Cc: <stable@vger.kernel.org>
Reported-by: Yi Zhang <yizhan@redhat.com>
Tested-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Fixed up missing 0 return in bdi_register_owner().
Signed-off-by: Jens Axboe <axboe@fb.com>
In case a submitted request gets stuck for some reason, the block layer
can prevent the request starvation by starting the scheduled timeout work.
If this stuck request occurs at the same time another thread has started
a queue freeze, the blk_mq_timeout_work will not be able to acquire the
queue reference and will return silently, thus not issuing the timeout.
But since the request is already holding a q_usage_counter reference and
is unable to complete, it will never release its reference, preventing
the queue from completing the freeze started by first thread. This puts
the request_queue in a hung state, forever waiting for the freeze
completion.
This was observed while running IO to a NVMe device at the same time we
toggled the CPU hotplug code. Eventually, once a request got stuck
requiring a timeout during a queue freeze, we saw the CPU Hotplug
notification code get stuck inside blk_mq_freeze_queue_wait, as shown in
the trace below.
[c000000deaf13690] [c000000deaf13738] 0xc000000deaf13738 (unreliable)
[c000000deaf13860] [c000000000015ce8] __switch_to+0x1f8/0x350
[c000000deaf138b0] [c000000000ade0e4] __schedule+0x314/0x990
[c000000deaf13940] [c000000000ade7a8] schedule+0x48/0xc0
[c000000deaf13970] [c0000000005492a4] blk_mq_freeze_queue_wait+0x74/0x110
[c000000deaf139e0] [c00000000054b6a8] blk_mq_queue_reinit_notify+0x1a8/0x2e0
[c000000deaf13a40] [c0000000000e7878] notifier_call_chain+0x98/0x100
[c000000deaf13a90] [c0000000000b8e08] cpu_notify_nofail+0x48/0xa0
[c000000deaf13ac0] [c0000000000b92f0] _cpu_down+0x2a0/0x400
[c000000deaf13b90] [c0000000000b94a8] cpu_down+0x58/0xa0
[c000000deaf13bc0] [c0000000006d5dcc] cpu_subsys_offline+0x2c/0x50
[c000000deaf13bf0] [c0000000006cd244] device_offline+0x104/0x140
[c000000deaf13c30] [c0000000006cd40c] online_store+0x6c/0xc0
[c000000deaf13c80] [c0000000006c8c78] dev_attr_store+0x68/0xa0
[c000000deaf13cc0] [c0000000003974d0] sysfs_kf_write+0x80/0xb0
[c000000deaf13d00] [c0000000003963e8] kernfs_fop_write+0x188/0x200
[c000000deaf13d50] [c0000000002e0f6c] __vfs_write+0x6c/0xe0
[c000000deaf13d90] [c0000000002e1ca0] vfs_write+0xc0/0x230
[c000000deaf13de0] [c0000000002e2cdc] SyS_write+0x6c/0x110
[c000000deaf13e30] [c000000000009204] system_call+0x38/0xb4
The fix is to allow the timeout work to execute in the window between
dropping the initial refcount reference and the release of the last
reference, which actually marks the freeze completion. This can be
achieved with percpu_refcount_tryget, which does not require the counter
to be alive. This way the timeout work can do it's job and terminate a
stuck request even during a freeze, returning its reference and avoiding
the deadlock.
Allowing the timeout to run is just a part of the fix, since for some
devices, we might get stuck again inside the device driver's timeout
handler, should it attempt to allocate a new request in that path -
which is a quite common action for Abort commands, which need to be sent
after a timeout. In NVMe, for instance, we call blk_mq_alloc_request
from inside the timeout handler, which will fail during a freeze, since
it also tries to acquire a queue reference.
I considered a similar change to blk_mq_alloc_request as a generic
solution for further device driver hangs, but we can't do that, since it
would allow new requests to disturb the freeze process. I thought about
creating a new function in the block layer to support unfreezable
requests for these occasions, but after working on it for a while, I
feel like this should be handled in a per-driver basis. I'm now
experimenting with changes to the NVMe timeout path, but I'm open to
suggestions of ways to make this generic.
Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Cc: Brian King <brking@linux.vnet.ibm.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: linux-nvme@lists.infradead.org
Cc: linux-block@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
I got a KASAN report of use-after-free:
==================================================================
BUG: KASAN: use-after-free in klist_iter_exit+0x61/0x70 at addr ffff8800b6581508
Read of size 8 by task trinity-c1/315
=============================================================================
BUG kmalloc-32 (Not tainted): kasan: bad access detected
-----------------------------------------------------------------------------
Disabling lock debugging due to kernel taint
INFO: Allocated in disk_seqf_start+0x66/0x110 age=144 cpu=1 pid=315
___slab_alloc+0x4f1/0x520
__slab_alloc.isra.58+0x56/0x80
kmem_cache_alloc_trace+0x260/0x2a0
disk_seqf_start+0x66/0x110
traverse+0x176/0x860
seq_read+0x7e3/0x11a0
proc_reg_read+0xbc/0x180
do_loop_readv_writev+0x134/0x210
do_readv_writev+0x565/0x660
vfs_readv+0x67/0xa0
do_preadv+0x126/0x170
SyS_preadv+0xc/0x10
do_syscall_64+0x1a1/0x460
return_from_SYSCALL_64+0x0/0x6a
INFO: Freed in disk_seqf_stop+0x42/0x50 age=160 cpu=1 pid=315
__slab_free+0x17a/0x2c0
kfree+0x20a/0x220
disk_seqf_stop+0x42/0x50
traverse+0x3b5/0x860
seq_read+0x7e3/0x11a0
proc_reg_read+0xbc/0x180
do_loop_readv_writev+0x134/0x210
do_readv_writev+0x565/0x660
vfs_readv+0x67/0xa0
do_preadv+0x126/0x170
SyS_preadv+0xc/0x10
do_syscall_64+0x1a1/0x460
return_from_SYSCALL_64+0x0/0x6a
CPU: 1 PID: 315 Comm: trinity-c1 Tainted: G B 4.7.0+ #62
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
ffffea0002d96000 ffff880119b9f918 ffffffff81d6ce81 ffff88011a804480
ffff8800b6581500 ffff880119b9f948 ffffffff8146c7bd ffff88011a804480
ffffea0002d96000 ffff8800b6581500 fffffffffffffff4 ffff880119b9f970
Call Trace:
[<ffffffff81d6ce81>] dump_stack+0x65/0x84
[<ffffffff8146c7bd>] print_trailer+0x10d/0x1a0
[<ffffffff814704ff>] object_err+0x2f/0x40
[<ffffffff814754d1>] kasan_report_error+0x221/0x520
[<ffffffff8147590e>] __asan_report_load8_noabort+0x3e/0x40
[<ffffffff83888161>] klist_iter_exit+0x61/0x70
[<ffffffff82404389>] class_dev_iter_exit+0x9/0x10
[<ffffffff81d2e8ea>] disk_seqf_stop+0x3a/0x50
[<ffffffff8151f812>] seq_read+0x4b2/0x11a0
[<ffffffff815f8fdc>] proc_reg_read+0xbc/0x180
[<ffffffff814b24e4>] do_loop_readv_writev+0x134/0x210
[<ffffffff814b4c45>] do_readv_writev+0x565/0x660
[<ffffffff814b8a17>] vfs_readv+0x67/0xa0
[<ffffffff814b8de6>] do_preadv+0x126/0x170
[<ffffffff814b92ec>] SyS_preadv+0xc/0x10
This problem can occur in the following situation:
open()
- pread()
- .seq_start()
- iter = kmalloc() // succeeds
- seqf->private = iter
- .seq_stop()
- kfree(seqf->private)
- pread()
- .seq_start()
- iter = kmalloc() // fails
- .seq_stop()
- class_dev_iter_exit(seqf->private) // boom! old pointer
As the comment in disk_seqf_stop() says, stop is called even if start
failed, so we need to reinitialise the private pointer to NULL when seq
iteration stops.
An alternative would be to set the private pointer to NULL when the
kmalloc() in disk_seqf_start() fails.
Cc: stable@vger.kernel.org
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
When a bio is cloned, the newly created bio must be associated with
the same blkcg as the original bio (if BLK_CGROUP is enabled). If
this operation is not performed, then the new bio is not associated
with any group, and the group of the current task is returned when
the group of the bio is requested.
Depending on the cloning frequency, this may cause a large
percentage of the bios belonging to a given group to be treated
as if belonging to other groups (in most cases as if belonging to
the root group). The expected group isolation may thereby be broken.
This commit adds the missing association in bio-cloning functions.
Fixes: da2f0f74cf ("Btrfs: add support for blkio controllers")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Nikolay Borisov <kernel@kyup.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
'nr_undestroyed_grps' in struct throtl_data was used to count
the number of throtl_grp related with throtl_data, but now
throtl_grp is tracked by blkcg_gq, so it is useless anymore.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The functionality for block device DAX was already removed with commit
acc93d30d7 ("Revert "block: enable dax for raw block devices"")
However, we still had a config option hanging around that was always
disabled because it depended on CONFIG_BROKEN. This config option was
introduced in commit 03cdadb040 ("block: disable block device DAX by
default")
This change reverts that commit, removing the dead config option.
Link: http://lkml.kernel.org/r/20160729182314.6368-1-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull block driver updates from Jens Axboe:
"This branch also contains core changes. I've come to the conclusion
that from 4.9 and forward, I'll be doing just a single branch. We
often have dependencies between core and drivers, and it's hard to
always split them up appropriately without pulling core into drivers
when that happens.
That said, this contains:
- separate secure erase type for the core block layer, from
Christoph.
- set of discard fixes, from Christoph.
- bio shrinking fixes from Christoph, as a followup up to the
op/flags change in the core branch.
- map and append request fixes from Christoph.
- NVMeF (NVMe over Fabrics) code from Christoph. This is pretty
exciting!
- nvme-loop fixes from Arnd.
- removal of ->driverfs_dev from Dan, after providing a
device_add_disk() helper.
- bcache fixes from Bhaktipriya and Yijing.
- cdrom subchannel read fix from Vchannaiah.
- set of lightnvm updates from Wenwei, Matias, Johannes, and Javier.
- set of drbd updates and fixes from Fabian, Lars, and Philipp.
- mg_disk error path fix from Bart.
- user notification for failed device add for loop, from Minfei.
- NVMe in general:
+ NVMe delay quirk from Guilherme.
+ SR-IOV support and command retry limits from Keith.
+ fix for memory-less NUMA node from Masayoshi.
+ use UINT_MAX for discard sectors, from Minfei.
+ cancel IO fixes from Ming.
+ don't allocate unused major, from Neil.
+ error code fixup from Dan.
+ use constants for PSDT/FUSE from James.
+ variable init fix from Jay.
+ fabrics fixes from Ming, Sagi, and Wei.
+ various fixes"
* 'for-4.8/drivers' of git://git.kernel.dk/linux-block: (115 commits)
nvme/pci: Provide SR-IOV support
nvme: initialize variable before logical OR'ing it
block: unexport various bio mapping helpers
scsi/osd: open code blk_make_request
target: stop using blk_make_request
block: simplify and export blk_rq_append_bio
block: ensure bios return from blk_get_request are properly initialized
virtio_blk: use blk_rq_map_kern
memstick: don't allow REQ_TYPE_BLOCK_PC requests
block: shrink bio size again
block: simplify and cleanup bvec pool handling
block: get rid of bio_rw and READA
block: don't ignore -EOPNOTSUPP blkdev_issue_write_same
block: introduce BLKDEV_DISCARD_ZERO to fix zeroout
NVMe: don't allocate unused nvme_major
nvme: avoid crashes when node 0 is memoryless node.
nvme: Limit command retries
loop: Make user notify for adding loop device failed
nvme-loop: fix nvme-loop Kconfig dependencies
nvmet: fix return value check in nvmet_subsys_alloc()
...
Pull core block updates from Jens Axboe:
- the big change is the cleanup from Mike Christie, cleaning up our
uses of command types and modified flags. This is what will throw
some merge conflicts
- regression fix for the above for btrfs, from Vincent
- following up to the above, better packing of struct request from
Christoph
- a 2038 fix for blktrace from Arnd
- a few trivial/spelling fixes from Bart Van Assche
- a front merge check fix from Damien, which could cause issues on
SMR drives
- Atari partition fix from Gabriel
- convert cfq to highres timers, since jiffies isn't granular enough
for some devices these days. From Jan and Jeff
- CFQ priority boost fix idle classes, from me
- cleanup series from Ming, improving our bio/bvec iteration
- a direct issue fix for blk-mq from Omar
- fix for plug merging not involving the IO scheduler, like we do for
other types of merges. From Tahsin
- expose DAX type internally and through sysfs. From Toshi and Yigal
* 'for-4.8/core' of git://git.kernel.dk/linux-block: (76 commits)
block: Fix front merge check
block: do not merge requests without consulting with io scheduler
block: Fix spelling in a source code comment
block: expose QUEUE_FLAG_DAX in sysfs
block: add QUEUE_FLAG_DAX for devices to advertise their DAX support
Btrfs: fix comparison in __btrfs_map_block()
block: atari: Return early for unsupported sector size
Doc: block: Fix a typo in queue-sysfs.txt
cfq-iosched: Charge at least 1 jiffie instead of 1 ns
cfq-iosched: Fix regression in bonnie++ rewrite performance
cfq-iosched: Convert slice_resid from u64 to s64
block: Convert fifo_time from ulong to u64
blktrace: avoid using timespec
block/blk-cgroup.c: Declare local symbols static
block/bio-integrity.c: Add #include "blk.h"
block/partition-generic.c: Remove a set-but-not-used variable
block: bio: kill BIO_MAX_SIZE
cfq-iosched: temporarily boost queue priority for idle classes
block: drbd: avoid to use BIO_MAX_SIZE
block: bio: remove BIO_MAX_SECTORS
...
Pull timer updates from Thomas Gleixner:
"This update provides the following changes:
- The rework of the timer wheel which addresses the shortcomings of
the current wheel (cascading, slow search for next expiring timer,
etc). That's the first major change of the wheel in almost 20
years since Finn implemted it.
- A large overhaul of the clocksource drivers init functions to
consolidate the Device Tree initialization
- Some more Y2038 updates
- A capability fix for timerfd
- Yet another clock chip driver
- The usual pile of updates, comment improvements all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (130 commits)
tick/nohz: Optimize nohz idle enter
clockevents: Make clockevents_subsys static
clocksource/drivers/time-armada-370-xp: Fix return value check
timers: Implement optimization for same expiry time in mod_timer()
timers: Split out index calculation
timers: Only wake softirq if necessary
timers: Forward the wheel clock whenever possible
timers/nohz: Remove pointless tick_nohz_kick_tick() function
timers: Optimize collect_expired_timers() for NOHZ
timers: Move __run_timers() function
timers: Remove set_timer_slack() leftovers
timers: Switch to a non-cascading wheel
timers: Reduce the CPU index space to 256k
timers: Give a few structs and members proper names
hlist: Add hlist_is_singular_node() helper
signals: Use hrtimer for sigtimedwait()
timers: Remove the deprecated mod_timer_pinned() API
timers, net/ipv4/inet: Initialize connection request timers as pinned
timers, drivers/tty/mips_ejtag: Initialize the poll timer as pinned
timers, drivers/tty/metag_da: Initialize the poll timer as pinned
...
For a front merge, the maximum number of sectors of the
request must be checked against the front merge BIO sector,
not the current sector of the request.
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Before merging a bio into an existing request, io scheduler is called to
get its approval first. However, the requests that come from a plug
flush may get merged by block layer without consulting with io
scheduler.
In case of CFQ, this can cause fairness problems. For instance, if a
request gets merged into a low weight cgroup's request, high weight cgroup
now will depend on low weight cgroup to get scheduled. If high weigt cgroup
needs that io request to complete before submitting more requests, then it
will also lose its timeslice.
Following script demonstrates the problem. Group g1 has a low weight, g2
and g3 have equal high weights but g2's requests are adjacent to g1's
requests so they are subject to merging. Due to these merges, g2 gets
poor disk time allocation.
cat > cfq-merge-repro.sh << "EOF"
#!/bin/bash
set -e
IO_ROOT=/mnt-cgroup/io
mkdir -p $IO_ROOT
if ! mount | grep -qw $IO_ROOT; then
mount -t cgroup none -oblkio $IO_ROOT
fi
cd $IO_ROOT
for i in g1 g2 g3; do
if [ -d $i ]; then
rmdir $i
fi
done
mkdir g1 && echo 10 > g1/blkio.weight
mkdir g2 && echo 495 > g2/blkio.weight
mkdir g3 && echo 495 > g3/blkio.weight
RUNTIME=10
(echo $BASHPID > g1/cgroup.procs &&
fio --readonly --name name1 --filename /dev/sdb \
--rw read --size 64k --bs 64k --time_based \
--runtime=$RUNTIME --offset=0k &> /dev/null)&
(echo $BASHPID > g2/cgroup.procs &&
fio --readonly --name name1 --filename /dev/sdb \
--rw read --size 64k --bs 64k --time_based \
--runtime=$RUNTIME --offset=64k &> /dev/null)&
(echo $BASHPID > g3/cgroup.procs &&
fio --readonly --name name1 --filename /dev/sdb \
--rw read --size 64k --bs 64k --time_based \
--runtime=$RUNTIME --offset=256k &> /dev/null)&
sleep $((RUNTIME+1))
for i in g1 g2 g3; do
echo ---- $i ----
cat $i/blkio.time
done
EOF
# ./cfq-merge-repro.sh
---- g1 ----
8:16 162
---- g2 ----
8:16 165
---- g3 ----
8:16 686
After applying the patch:
# ./cfq-merge-repro.sh
---- g1 ----
8:16 90
---- g2 ----
8:16 445
---- g3 ----
8:16 471
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Provides the ability to identify DAX enabled devices in userspace.
Signed-off-by: Yigal Korman <yigal@plexistor.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
They are unused and potential new users really should use the
blk_rq_map* versions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
I wish the OSD code could simply use blk_rq_map_* helpers like
everyone else, but the complex nature of deciding if we have
DATA IN and/or DATA OUT buffers might make this impossible
(at least for a mere human like me).
But using blk_rq_append_bio at least allows sharing the setup code
between request with or without dat a buffers, and given that this
is the last user of blk_make_request it allows getting rid of that
somewhat awkward interface.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Boaz Harrosh <ooo@electrozaur.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The target SCSI passthrough backend is much better served with the low-level
blk_rq_append_bio construct then the helpers built on top of it, so export it.
Also use the opportunity to remove the pointless request_queue argument and
make the code flow a little more readable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
blk_get_request is used for BLOCK_PC and similar passthrough requests.
Currently we always need to call blk_rq_set_block_pc or an open coded
version of it to allow appending bios using the request mapping helpers
later on, which is a somewhat awkward API. Instead move the
initialization part of blk_rq_set_block_pc into blk_get_request, so that
we always have a safe to use request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Instead of a flag and an index just make sure an index of 0 means
no need to free the bvec array. Also move the constants related
to the bvec pools together and use a consistent naming scheme for
them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Shaohua Li
Johannes Thumshirn
Bart Van Assche
Kent Overstreet
Christoph Hellwig
Jens Axboe
Ming Lei
Arnd Bergmann
Linus Torvalds
Adam Manzanares
Shaun Tancheff
Hannes Reinecke
Shaun Tancheff
Damien Le Moal
Tomasz Majchrzak
Darrick J. Wong
Emese Revfy
Glauber Costa
Sebastian Andrzej Siewior
Thomas Gleixner
Guoqing Jiang
Matias Bjørling
Vivek Goyal
Stephen Rothwell
Omar Sandoval
Mike Snitzer
Linus Walleij
Stephen Bates
Ming Lei
Adrian Hunter
Dan Williams
Gabriel Krisman Bertazi
Vegard Nossum
Paolo Valente
Hou Tao
Ross Zwisler
Tahsin Erdogan
Yigal Korman