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Merge tag 'for-4.21/block-20181221' of git://git.kernel.dk/linux-block
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Pull block updates from Jens Axboe:
 "This is the main pull request for block/storage for 4.21.

  Larger than usual, it was a busy round with lots of goodies queued up.
  Most notable is the removal of the old IO stack, which has been a long
  time coming. No new features for a while, everything coming in this
  week has all been fixes for things that were previously merged.

  This contains:

   - Use atomic counters instead of semaphores for mtip32xx (Arnd)

   - Cleanup of the mtip32xx request setup (Christoph)

   - Fix for circular locking dependency in loop (Jan, Tetsuo)

   - bcache (Coly, Guoju, Shenghui)
      * Optimizations for writeback caching
      * Various fixes and improvements

   - nvme (Chaitanya, Christoph, Sagi, Jay, me, Keith)
      * host and target support for NVMe over TCP
      * Error log page support
      * Support for separate read/write/poll queues
      * Much improved polling
      * discard OOM fallback
      * Tracepoint improvements

   - lightnvm (Hans, Hua, Igor, Matias, Javier)
      * Igor added packed metadata to pblk. Now drives without metadata
        per LBA can be used as well.
      * Fix from Geert on uninitialized value on chunk metadata reads.
      * Fixes from Hans and Javier to pblk recovery and write path.
      * Fix from Hua Su to fix a race condition in the pblk recovery
        code.
      * Scan optimization added to pblk recovery from Zhoujie.
      * Small geometry cleanup from me.

   - Conversion of the last few drivers that used the legacy path to
     blk-mq (me)

   - Removal of legacy IO path in SCSI (me, Christoph)

   - Removal of legacy IO stack and schedulers (me)

   - Support for much better polling, now without interrupts at all.
     blk-mq adds support for multiple queue maps, which enables us to
     have a map per type. This in turn enables nvme to have separate
     completion queues for polling, which can then be interrupt-less.
     Also means we're ready for async polled IO, which is hopefully
     coming in the next release.

   - Killing of (now) unused block exports (Christoph)

   - Unification of the blk-rq-qos and blk-wbt wait handling (Josef)

   - Support for zoned testing with null_blk (Masato)

   - sx8 conversion to per-host tag sets (Christoph)

   - IO priority improvements (Damien)

   - mq-deadline zoned fix (Damien)

   - Ref count blkcg series (Dennis)

   - Lots of blk-mq improvements and speedups (me)

   - sbitmap scalability improvements (me)

   - Make core inflight IO accounting per-cpu (Mikulas)

   - Export timeout setting in sysfs (Weiping)

   - Cleanup the direct issue path (Jianchao)

   - Export blk-wbt internals in block debugfs for easier debugging
     (Ming)

   - Lots of other fixes and improvements"

* tag 'for-4.21/block-20181221' of git://git.kernel.dk/linux-block: (364 commits)
  kyber: use sbitmap add_wait_queue/list_del wait helpers
  sbitmap: add helpers for add/del wait queue handling
  block: save irq state in blkg_lookup_create()
  dm: don't reuse bio for flushes
  nvme-pci: trace SQ status on completions
  nvme-rdma: implement polling queue map
  nvme-fabrics: allow user to pass in nr_poll_queues
  nvme-fabrics: allow nvmf_connect_io_queue to poll
  nvme-core: optionally poll sync commands
  block: make request_to_qc_t public
  nvme-tcp: fix spelling mistake "attepmpt" -> "attempt"
  nvme-tcp: fix endianess annotations
  nvmet-tcp: fix endianess annotations
  nvme-pci: refactor nvme_poll_irqdisable to make sparse happy
  nvme-pci: only set nr_maps to 2 if poll queues are supported
  nvmet: use a macro for default error location
  nvmet: fix comparison of a u16 with -1
  blk-mq: enable IO poll if .nr_queues of type poll > 0
  blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()
  blk-mq: skip zero-queue maps in blk_mq_map_swqueue
  ...
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torvalds committed Dec 28, 2018
2 parents b12a912 + 00203ba commit 0e9da3f
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12 changes: 10 additions & 2 deletions Documentation/ABI/testing/sysfs-block
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Expand Up @@ -244,7 +244,7 @@ Description:

What: /sys/block/<disk>/queue/zoned
Date: September 2016
Contact: Damien Le Moal <damien.lemoal@hgst.com>
Contact: Damien Le Moal <damien.lemoal@wdc.com>
Description:
zoned indicates if the device is a zoned block device
and the zone model of the device if it is indeed zoned.
Expand All @@ -259,6 +259,14 @@ Description:
zone commands, they will be treated as regular block
devices and zoned will report "none".

What: /sys/block/<disk>/queue/nr_zones
Date: November 2018
Contact: Damien Le Moal <damien.lemoal@wdc.com>
Description:
nr_zones indicates the total number of zones of a zoned block
device ("host-aware" or "host-managed" zone model). For regular
block devices, the value is always 0.

What: /sys/block/<disk>/queue/chunk_sectors
Date: September 2016
Contact: Hannes Reinecke <hare@suse.com>
Expand All @@ -268,6 +276,6 @@ Description:
indicates the size in 512B sectors of the RAID volume
stripe segment. For a zoned block device, either
host-aware or host-managed, chunk_sectors indicates the
size of 512B sectors of the zones of the device, with
size in 512B sectors of the zones of the device, with
the eventual exception of the last zone of the device
which may be smaller.
8 changes: 5 additions & 3 deletions Documentation/admin-guide/cgroup-v2.rst
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Expand Up @@ -1879,8 +1879,10 @@ following two functions.

wbc_init_bio(@wbc, @bio)
Should be called for each bio carrying writeback data and
associates the bio with the inode's owner cgroup. Can be
called anytime between bio allocation and submission.
associates the bio with the inode's owner cgroup and the
corresponding request queue. This must be called after
a queue (device) has been associated with the bio and
before submission.

wbc_account_io(@wbc, @page, @bytes)
Should be called for each data segment being written out.
Expand All @@ -1899,7 +1901,7 @@ the configuration, the bio may be executed at a lower priority and if
the writeback session is holding shared resources, e.g. a journal
entry, may lead to priority inversion. There is no one easy solution
for the problem. Filesystems can try to work around specific problem
cases by skipping wbc_init_bio() or using bio_associate_blkcg()
cases by skipping wbc_init_bio() and using bio_associate_blkg()
directly.


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88 changes: 0 additions & 88 deletions Documentation/block/biodoc.txt
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Expand Up @@ -65,7 +65,6 @@ Description of Contents:
3.2.3 I/O completion
3.2.4 Implications for drivers that do not interpret bios (don't handle
multiple segments)
3.2.5 Request command tagging
3.3 I/O submission
4. The I/O scheduler
5. Scalability related changes
Expand Down Expand Up @@ -708,93 +707,6 @@ is crossed on completion of a transfer. (The end*request* functions should
be used if only if the request has come down from block/bio path, not for
direct access requests which only specify rq->buffer without a valid rq->bio)

3.2.5 Generic request command tagging

3.2.5.1 Tag helpers

Block now offers some simple generic functionality to help support command
queueing (typically known as tagged command queueing), ie manage more than
one outstanding command on a queue at any given time.

blk_queue_init_tags(struct request_queue *q, int depth)

Initialize internal command tagging structures for a maximum
depth of 'depth'.

blk_queue_free_tags((struct request_queue *q)

Teardown tag info associated with the queue. This will be done
automatically by block if blk_queue_cleanup() is called on a queue
that is using tagging.

The above are initialization and exit management, the main helpers during
normal operations are:

blk_queue_start_tag(struct request_queue *q, struct request *rq)

Start tagged operation for this request. A free tag number between
0 and 'depth' is assigned to the request (rq->tag holds this number),
and 'rq' is added to the internal tag management. If the maximum depth
for this queue is already achieved (or if the tag wasn't started for
some other reason), 1 is returned. Otherwise 0 is returned.

blk_queue_end_tag(struct request_queue *q, struct request *rq)

End tagged operation on this request. 'rq' is removed from the internal
book keeping structures.

To minimize struct request and queue overhead, the tag helpers utilize some
of the same request members that are used for normal request queue management.
This means that a request cannot both be an active tag and be on the queue
list at the same time. blk_queue_start_tag() will remove the request, but
the driver must remember to call blk_queue_end_tag() before signalling
completion of the request to the block layer. This means ending tag
operations before calling end_that_request_last()! For an example of a user
of these helpers, see the IDE tagged command queueing support.

3.2.5.2 Tag info

Some block functions exist to query current tag status or to go from a
tag number to the associated request. These are, in no particular order:

blk_queue_tagged(q)

Returns 1 if the queue 'q' is using tagging, 0 if not.

blk_queue_tag_request(q, tag)

Returns a pointer to the request associated with tag 'tag'.

blk_queue_tag_depth(q)

Return current queue depth.

blk_queue_tag_queue(q)

Returns 1 if the queue can accept a new queued command, 0 if we are
at the maximum depth already.

blk_queue_rq_tagged(rq)

Returns 1 if the request 'rq' is tagged.

3.2.5.2 Internal structure

Internally, block manages tags in the blk_queue_tag structure:

struct blk_queue_tag {
struct request **tag_index; /* array or pointers to rq */
unsigned long *tag_map; /* bitmap of free tags */
struct list_head busy_list; /* fifo list of busy tags */
int busy; /* queue depth */
int max_depth; /* max queue depth */
};

Most of the above is simple and straight forward, however busy_list may need
a bit of explaining. Normally we don't care too much about request ordering,
but in the event of any barrier requests in the tag queue we need to ensure
that requests are restarted in the order they were queue.

3.3 I/O Submission

The routine submit_bio() is used to submit a single io. Higher level i/o
Expand Down
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