fix #28528017

In case of virtio-blk device, checking /sys/block/<device>/queue/io_poll
will show 1 and user can't disable it. Actually virtio-blk doesn't
support poll yet, so it will confuse end user. The root cause is mq
initialization will default set bit QUEUE_FLAG_POLL.

This fix takes ideas from the following upstream commits:
6544d229bf43 ("block: enable polling by default if a poll map is initalized")
6e0de61107f0 ("blk-mq: remove QUEUE_FLAG_POLL from default MQ flags")
Since we don't want to get HCTX_TYPE_POLL related logic involved, so
just check mq_ops->poll and then set QUEUE_FLAG_POLL.
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

to #24913189

commit c780e86dd48ef6467a1146cf7d0fe1e05a635039 upstream.

KASAN is reporting that __blk_add_trace() has a use-after-free issue
when accessing q->blk_trace. Indeed the switching of block tracing (and
thus eventual freeing of q->blk_trace) is completely unsynchronized with
the currently running tracing and thus it can happen that the blk_trace
structure is being freed just while __blk_add_trace() works on it.
Protect accesses to q->blk_trace by RCU during tracing and make sure we
wait for the end of RCU grace period when shutting down tracing. Luckily
that is rare enough event that we can afford that. Note that postponing
the freeing of blk_trace to an RCU callback should better be avoided as
it could have unexpected user visible side-effects as debugfs files
would be still existing for a short while block tracing has been shut
down.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=205711
CC: stable@vger.kernel.org
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Tested-by: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Reported-by: NTristan Madani <tristmd@gmail.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
[bwh: Backported to 4.19: adjust context]
Signed-off-by: NBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: NSasha Levin <sashal@kernel.org>
References: CVE-2019-19768
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 1db4909e76f64a85f4aaa187f0f683f5c85a471d upstream.

Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime
from block layer's view, actually they don't because userspace may
grab one kobject anytime via sysfs.

This patch fixes the issue by the following approach:

1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing
all ctxs

2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release
handler of .mq_kobj

3) grab one ref of .mq_kobj before initializing each ctx->kobj, so that
.mq_kobj is always released after all ctxs are freed.

This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE
is enabled.
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

Background:
  We do not have a dependable block layer interface to determine whether
block device has io requests which have not been completed for somewhat
long time. Currently we have 'in_flight' interface, it counts the number
of I/O requests that have been issued to the device driver but have
not yet completed, and it does not include I/O requests that are in the
queue but not yet issued to the device driver, which means it will not
count io requests that have been stucked in block layer.
  Also say that there are steady io requests issued to device driver,
'in_flight' maybe always non-zero, but you could not determine whether
there is one io request which has not been completed for too long.

Solution:
  To find io requests which have not been completed for too long, here
add 3 new inferfaces:
  /sys/block/vdb/queue/hang_threshold
If one io request's running time has been greater than this value, count
this io as hang.

  /sys/block/vdb/hang
Show read/write io requests' hang counter.

  /sys/kernel/debug/block/vdb/rq_hang
Show all hang io requests's detailed info, like below:
  ffff97db96301200 {.op=WRITE, .cmd_flags=SYNC, .rq_flags=STARTED|
ELVPRIV|IO_STAT|STATS, .state=in_flight, .tag=30, .internal_tag=169,
.start_time_ns=140634088407, .io_start_time_ns=140634102958,
.current_time=146497371953, .bio = ffff97db91e8e000,
.bio_pages = { ffffd096a0602540 }, .bio = ffff97db91e8ec00,
.bio_pages = { ffffd096a070eec0 }, .bio = ffff97db91e8f600,
.bio_pages = { ffffd096a0424cc0 }, .bio = ffff97db91e8f300,
.bio_pages = { ffffd096a0600a80 }}

With above info, we can easily see this request's latency distribution,
and see next patch for bio_pages's usage.

Note, /sys/kernel/debug/block/vdb/rq_hang only exists in blk-mq device driver
and needs CONFIG_BLK_DEBUG_FS enabled.
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit 529262d56dbebe6a26df5d2fd24cc0e1bc8579e5 upstream.

This was intended to support users like nvme multipath, but is just
getting in the way and adding another indirect call.
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 0a1b8b87d064a47fad9ec475316002da28559207 upstream.

blk_poll() has always kept spinning until it found an IO. This is
fine for SYNC polling, since we need to find one request we have
pending, but in preparation for ASYNC polling it can be beneficial
to just check if we have any entries available or not.

Existing callers are converted to pass in 'spin == true', to retain
the old behavior.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 1052b8ac5282daf35df331edcbdb645839d17e6a upstream.

If we want to support async IO polling, then we have to allow finding
completions that aren't just for the one we are looking for. Always pass
in -1 to the mq_ops->poll() helper, and have that return how many events
were found in this poll loop.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 85f4d4b65fdd67f1d6dc9eeb1d91923cef07eb6a upstream.

We currently only really support sync poll, ie poll with 1 IO in flight.
This prepares us for supporting async poll.

Note that the returned value isn't necessarily 100% accurate. If poll
races with IRQ completion, we assume that the fact that the task is now
runnable means we found at least one entry. In reality it could be more
than 1, or not even 1. This is fine, the caller will just need to take
this into account.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

We reserve some fields beforehand for core structures prone to change,
so that we won't hurt when extra fields have to be added for hotfix,
thereby inceasing the success rate, we even can hot add features with
this enhancement.

After reserving, normally cache does not matter as the reserved fields
(usually at tail) are not accessed at all.

Currently involve the following structures:
    MM:
    struct zone
    struct pglist_data
    struct mm_struct
    struct vm_area_struct
    struct mem_cgroup
    struct writeback_control

    Block:
    struct gendisk
    struct backing_dev_info
    struct bio
    struct queue_limits
    struct request_queue
    struct blkcg
    struct blkcg_policy
    struct blk_mq_hw_ctx
    struct blk_mq_tag_set
    struct blk_mq_queue_data
    struct blk_mq_ops
    struct elevator_mq_ops
    struct inode
    struct dentry
    struct address_space
    struct block_device
    struct hd_struct
    struct bio_set

    Network:
    struct sk_buff
    struct sock
    struct net_device_ops
    struct xt_target
    struct dst_entry
    struct dst_ops
    struct fib_rule

    Scheduler:
    struct task_struct
    struct cfs_rq
    struct rq
    struct sched_statistics
    struct sched_entity
    struct signal_struct
    struct task_group
    struct cpuacct

    cgroup:
    struct cgroup_root
    struct cgroup_subsys_state
    struct cgroup_subsys
    struct css_set
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>
[ caspar: use SPDX-License-Identifier ]
Signed-off-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 6f816b4b746c2241540e537682d30d8e9997d674 upstream.

There are currently two start time timestamps - start_time_ns and
io_start_time_ns.  The former marks the request allocation and and the
second issue-to-device time.  The planned io.weight controller needs
to measure the total time bios take to execute after it leaves rq_qos
including the time spent waiting for request to become available,
which can easily dominate on saturated devices.

This patch adds request->alloc_time_ns which records when the request
allocation attempt started.  As it isn't used for the usual stats,
make it optional behind CONFIG_BLK_RQ_ALLOC_TIME and
QUEUE_FLAG_RQ_ALLOC_TIME so that it can be compiled out when there are
no users and it's active only on queues which need it even when
compiled in.

v2: s/pre_start_time/alloc_time/ and add CONFIG_BLK_RQ_ALLOC_TIME
    gating as suggested by Jens.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit cd84a62e0078dce09f4ed349bec84f86c9d54b30 upstream.

The RQF_PREEMPT flag is used for three purposes:
- In the SCSI core, for making sure that power management requests
  are executed even if a device is in the "quiesced" state.
- For domain validation by SCSI drivers that use the parallel port.
- In the IDE driver, for IDE preempt requests.
Rename "preempt-only" into "pm-only" because the primary purpose of
this mode is power management. Since the power management core may
but does not have to resume a runtime suspended device before
performing system-wide suspend and since a later patch will set
"pm-only" mode as long as a block device is runtime suspended, make
it possible to set "pm-only" mode from more than one context. Since
with this change scsi_device_quiesce() is no longer idempotent, make
that function return early if it is called for a quiesced queue.
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After merging the iolatency policy, we potentially now have 4 policies
being registered, but only support 3. This causes one of them to fail
loading. Takashi reports that BFQ no longer works for him, because it
fails to load due to policy registration failure.

Bump to 5 policies, and also add a warning for when we have exceeded
the global amount. If we have to touch this again, we should switch
to a dynamic scheme instead.
Reported-by: NTakashi Iwai <tiwai@suse.de>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Tested-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Commit 12f5b931 ("blk-mq: Remove generation seqeunce") removed the
only seqcount_t and u64_stats_sync instances from <linux/blkdev.h> but
did not remove the corresponding #include directives. Since these
include directives are no longer needed, remove them.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>,
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This allows bio_integrity_bytes() to be called from drivers instead of
open coding it.
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NGreg Edwards <gedwards@ddn.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

c11f0c0b ("block/mm: make bdev_ops->rw_page() take a bool for
read/write") replaced @OP with boolean @is_write, which limited the
amount of information going into ->rw_page() and more importantly
page_endio(), which removed the need to expose block internals to mm.

Unfortunately, we want to track discards separately and @is_write
isn't enough information.  This patch updates bdev_ops->rw_page() to
take REQ_OP instead but leaves page_endio() to take bool @is_write.
This allows the block part of operations to have enough information
while not leaking it to mm.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove blkdev_entry_to_request() macro, which remained unused through
the observable history, also note that it repeats list_entry_rq() macro
verbatim.
Signed-off-by: NVladimir Zapolskiy <vz@mleia.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis.  Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We have to remove synchronize_rcu() from blk_queue_cleanup(),
otherwise long delay can be caused during lun probe. For removing
it, we have to avoid to iterate the set->tag_list in IO path, eg,
blk_mq_sched_restart().

This patch reverts 5b79413946d (Revert "blk-mq: don't handle
TAG_SHARED in restart"). Given we have fixed enough IO hang issue,
and there isn't any reason to restart all queues in one tags any more,
see the following reasons:

1) blk-mq core can deal with shared-tags case well via blk_mq_get_driver_tag(),
which can wake up queues waiting for driver tag.

2) SCSI is a bit special because it may return BLK_STS_RESOURCE if queue,
target or host is ready, but SCSI built-in restart can cover all these well,
see scsi_end_request(), queue will be rerun after any request initiated from
this host/target is completed.

In my test on scsi_debug(8 luns), this patch may improve IOPS by 20% ~ 30%
when running I/O on these 8 luns concurrently.

Fixes: 705cda97 ("blk-mq: Make it safe to use RCU to iterate over blk_mq_tag_set.tag_list")
Cc: Omar Sandoval <osandov@fb.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reported-by: NAndrew Jones <drjones@redhat.com>
Tested-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Exclude zoned block device members from struct request_queue for
CONFIG_BLK_DEV_ZONED == n. Avoid breaking the build by only building
the code that uses these struct request_queue members if
CONFIG_BLK_DEV_ZONED != n.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Cc: Matias Bjorling <mb@lightnvm.io>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since the implementation of blk_queue_nr_zones() is trivial and since
it only has a single caller, inline this function.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Cc: Matias Bjorling <mb@lightnvm.io>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove this function since it has no callers. This function was
introduced in commit 6cc77e9c ("block: introduce zoned block
devices zone write locking").
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjorling <mb@lightnvm.io>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

A device may have boundary restrictions where the number of sectors
between boundaries exceeds its max transfer size. In this case, we need
to cap the max size to the smaller of the two limits.
Reported-by: NJitendra Bhivare <jitendra.bhivare@broadcom.com>
Tested-by: NJitendra Bhivare <jitendra.bhivare@broadcom.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This function is entirely unused, so remove it and the tag_queue_busy
member of struct request_queue.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We can currently call the timeout handler again on a request that has
already been handed over to the timeout handler.  Prevent that with a new
flag.

Fixes: 12f5b931 ("blk-mq: Remove generation seqeunce")
Reported-by: NAndrew Randrianasulu <randrianasulu@gmail.com>
Tested-by: NAndrew Randrianasulu <randrianasulu@gmail.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Convert the core block functionality to embedded bio sets.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NKent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

After the recent timeout handling changes, we have two holes in
the struct. Move the timeout near the deadline, killing both,
and moving related members closer together. On my config on
x86-64, this shrinks struct request from 312 to 304 bytes.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The BLK_EH_NOT_HANDLED implies nothing happen, but very often that
is not what is happening - instead the driver already completed the
command.  Fix the symbolic name to reflect that a little better.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch simplifies the timeout handling by relying on the request
reference counting to ensure the iterator is operating on an inflight
and truly timed out request. Since the reference counting prevents the
tag from being reallocated, the block layer no longer needs to prevent
drivers from completing their requests while the timeout handler is
operating on it: a driver completing a request is allowed to proceed to
the next state without additional syncronization with the block layer.

This also removes any need for generation sequence numbers since the
request lifetime is prevented from being reallocated as a new sequence
while timeout handling is operating on it.

To enables this a refcount is added to struct request so that request
users can be sure they're operating on the same request without it
changing while they're processing it.  The request's tag won't be
released for reuse until both the timeout handler and the completion
are done with it.
Signed-off-by: NKeith Busch <keith.busch@intel.com>
[hch: slight cleanups, added back submission side hctx lock, use cmpxchg
 for completions]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Switch everyone to blk_get_request_flags, and then rename
blk_get_request_flags to blk_get_request.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Currently, struct request has four timestamp fields:

- A start time, set at get_request time, in jiffies, used for iostats
- An I/O start time, set at start_request time, in ktime nanoseconds,
  used for blk-stats (i.e., wbt, kyber, hybrid polling)
- Another start time and another I/O start time, used for cfq and bfq

These can all be consolidated into one start time and one I/O start
time, both in ktime nanoseconds, shaving off up to 16 bytes from struct
request depending on the kernel config.
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

cfq and bfq have some internal fields that use sched_clock() which can
trivially use ktime_get_ns() instead. Their timestamp fields in struct
request can also use ktime_get_ns(), which resolves the 8 year old
comment added by commit 28f4197e ("block: disable preemption before
using sched_clock()").
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

struct blk_issue_stat squashes three things into one u64:

- The time the driver started working on a request
- The original size of the request (for the io.low controller)
- Flags for writeback throttling

It turns out that on x86_64, we have a 4 byte hole in struct request
which we can fill with the non-timestamp fields from blk_issue_stat,
simplifying things quite a bit.
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since SCSI scanning occurs asynchronously, since sd_revalidate_disk() is
called from sd_probe_async() and since sd_revalidate_disk() calls
sd_zbc_read_zones() it can happen that sd_zbc_read_zones() is called
concurrently with blkdev_report_zones() and/or blkdev_reset_zones().  That can
cause these functions to fail with -EIO because sd_zbc_read_zones() e.g. sets
q->nr_zones to zero before restoring it to the actual value, even if no drive
characteristics have changed.  Avoid that this can happen by making the
following changes:

- Protect the code that updates zone information with blk_queue_enter()
  and blk_queue_exit().
- Modify sd_zbc_setup_seq_zones_bitmap() and sd_zbc_setup() such that
  these functions do not modify struct scsi_disk before all zone
  information has been obtained.

Note: since commit 055f6e18 ("block: Make q_usage_counter also track
legacy requests"; kernel v4.15) the request queue freezing mechanism also
affects legacy request queues.

Fixes: 89d94756 ("sd: Implement support for ZBC devices")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: stable@vger.kernel.org # v4.16
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

So we can check FUA support status from the iomap direct IO code.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It happens often while I'm preparing a patch for a block driver that
I'm wondering: is a definition of SECTOR_SIZE and/or SECTOR_SHIFT
available for this driver? Do I have to introduce definitions of these
constants before I can use these constants? To avoid this confusion,
move the existing definitions of SECTOR_SIZE and SECTOR_SHIFT into the
<linux/blkdev.h> header file such that these become available for all
block drivers. Make the SECTOR_SIZE definition in the uapi msdos_fs.h
header file conditional to avoid that including that header file after
<linux/blkdev.h> causes the compiler to complain about a SECTOR_SIZE
redefinition.

Note: the SECTOR_SIZE / SECTOR_SHIFT / SECTOR_BITS definitions have
not been removed from uapi header files nor from NAND drivers in
which these constants are used for another purpose than converting
block layer offsets and sizes into a number of sectors.

Cc: David S. Miller <davem@davemloft.net>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Reviewed-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch helps to avoid that new code gets introduced in block drivers
that manipulates queue flags without holding the queue lock when that
lock should be held.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since it is not safe to use queue_flag_(set|clear)_unlocked()
without holding the queue lock after the sysfs entries for a
queue have been created, complain if this happens.

Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Introduce functions that modify the queue flags and that protect
these modifications with the request queue lock. Except for moving
one wake_up_all() call from inside to outside a critical section,
this patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>