Merge tag 'for-5.5/block-20191121' of git://git.kernel.dk/linux-block

Pull core block updates from Jens Axboe:
 "Due to more granular branches, this one is small and will be followed
  with other core branches that add specific features. I meant to just
  have a core and drivers branch, but external dependencies we ended up
  adding a few more that are also core.

  The changes are:

   - Fixes and improvements for the zoned device support (Ajay, Damien)

   - sed-opal table writing and datastore UID (Revanth)

   - blk-cgroup (and bfq) blk-cgroup stat fixes (Tejun)

   - Improvements to the block stats tracking (Pavel)

   - Fix for overruning sysfs buffer for large number of CPUs (Ming)

   - Optimization for small IO (Ming, Christoph)

   - Fix typo in RWH lifetime hint (Eugene)

   - Dead code removal and documentation (Bart)

   - Reduction in memory usage for queue and tag set (Bart)

   - Kerneldoc header documentation (André)

   - Device/partition revalidation fixes (Jan)

   - Stats tracking for flush requests (Konstantin)

   - Various other little fixes here and there (et al)"

* tag 'for-5.5/block-20191121' of git://git.kernel.dk/linux-block: (48 commits)
  Revert "block: split bio if the only bvec's length is > SZ_4K"
  block: add iostat counters for flush requests
  block,bfq: Skip tracing hooks if possible
  block: sed-opal: Introduce SUM_SET_LIST parameter and append it using 'add_token_u64'
  blk-cgroup: cgroup_rstat_updated() shouldn't be called on cgroup1
  block: Don't disable interrupts in trigger_softirq()
  sbitmap: Delete sbitmap_any_bit_clear()
  blk-mq: Delete blk_mq_has_free_tags() and blk_mq_can_queue()
  block: split bio if the only bvec's length is > SZ_4K
  block: still try to split bio if the bvec crosses pages
  blk-cgroup: separate out blkg_rwstat under CONFIG_BLK_CGROUP_RWSTAT
  blk-cgroup: reimplement basic IO stats using cgroup rstat
  blk-cgroup: remove now unused blkg_print_stat_{bytes|ios}_recursive()
  blk-throtl: stop using blkg->stat_bytes and ->stat_ios
  bfq-iosched: stop using blkg->stat_bytes and ->stat_ios
  bfq-iosched: relocate bfqg_*rwstat*() helpers
  block: add zone open, close and finish ioctl support
  block: add zone open, close and finish operations
  block: Simplify REQ_OP_ZONE_RESET_ALL handling
  block: Remove REQ_OP_ZONE_RESET plugging
  ...

4 files changed, 32 insertions, 2 deletions

diff --git a/Documentation/ABI/testing/procfs-diskstats b/Documentation/ABI/testing/procfs-diskstats
index 2c44b4f1b060..70dcaf2481f4 100644
--- a/Documentation/ABI/testing/procfs-diskstats
+++ b/Documentation/ABI/testing/procfs-diskstats
@@ -29,4 +29,9 @@ Description:
 		17 - sectors discarded
 		18 - time spent discarding
 
+		Kernel 5.5+ appends two more fields for flush requests:
+
+		19 - flush requests completed successfully
+		20 - time spent flushing
+
 		For more details refer to Documentation/admin-guide/iostats.rst
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index f8c7c7126bb1..ed8c14f161ee 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -15,6 +15,12 @@ Description:
 		 9 - I/Os currently in progress
 		10 - time spent doing I/Os (ms)
 		11 - weighted time spent doing I/Os (ms)
+		12 - discards completed
+		13 - discards merged
+		14 - sectors discarded
+		15 - time spent discarding (ms)
+		16 - flush requests completed
+		17 - time spent flushing (ms)
 		For more details refer Documentation/admin-guide/iostats.rst
 
 
diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst
index 5d63b18bd6d1..4f0462af3ca7 100644
--- a/Documentation/admin-guide/iostats.rst
+++ b/Documentation/admin-guide/iostats.rst
@@ -121,6 +121,15 @@ Field 15 -- # of milliseconds spent discarding
     This is the total number of milliseconds spent by all discards (as
     measured from __make_request() to end_that_request_last()).
 
+Field 16 -- # of flush requests completed
+    This is the total number of flush requests completed successfully.
+
+    Block layer combines flush requests and executes at most one at a time.
+    This counts flush requests executed by disk. Not tracked for partitions.
+
+Field 17 -- # of milliseconds spent flushing
+    This is the total number of milliseconds spent by all flush requests.
+
 To avoid introducing performance bottlenecks, no locks are held while
 modifying these counters.  This implies that minor inaccuracies may be
 introduced when changes collide, so (for instance) adding up all the
diff --git a/Documentation/block/stat.rst b/Documentation/block/stat.rst
index 9c07bc22b0bc..77311335c08b 100644
--- a/Documentation/block/stat.rst
+++ b/Documentation/block/stat.rst
@@ -41,6 +41,8 @@ discard I/Os    requests      number of discard I/Os processed
 discard merges  requests      number of discard I/Os merged with in-queue I/O
 discard sectors sectors       number of sectors discarded
 discard ticks   milliseconds  total wait time for discard requests
+flush I/Os      requests      number of flush I/Os processed
+flush ticks     milliseconds  total wait time for flush requests
 =============== ============= =================================================
 
 read I/Os, write I/Os, discard I/0s
@@ -48,6 +50,14 @@ read I/Os, write I/Os, discard I/0s
 
 These values increment when an I/O request completes.
 
+flush I/Os
+==========
+
+These values increment when an flush I/O request completes.
+
+Block layer combines flush requests and executes at most one at a time.
+This counts flush requests executed by disk. Not tracked for partitions.
+
 read merges, write merges, discard merges
 =========================================
 
@@ -62,8 +72,8 @@ discarded from this block device.  The "sectors" in question are the
 standard UNIX 512-byte sectors, not any device- or filesystem-specific
 block size.  The counters are incremented when the I/O completes.
 
-read ticks, write ticks, discard ticks
-======================================
+read ticks, write ticks, discard ticks, flush ticks
+===================================================
 
 These values count the number of milliseconds that I/O requests have
 waited on this block device.  If there are multiple I/O requests waiting,