Seperate read and write statistics of in_flight requests

Currently, there is a single in_flight counter measuring the number of
requests in the request_queue. But some monitoring tools would like to
know how many read requests and write requests are in progress. Split the
current in_flight counter into two seperate counters for read and write.

This information is exported as a sysfs attribute, as changing the
currently available stat files would break the existing tools.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

3 files changed, 7 insertions, 5 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 982d634e67f9..182ebe3eb9e0 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -69,7 +69,7 @@ static void drive_stat_acct(struct request *rq, int new_io)
                 part_stat_inc(cpu, part, merges[rw]);
         else {
                 part_round_stats(cpu, part);
-                part_inc_in_flight(part);
+                part_inc_in_flight(part, rw);
         }
 
         part_stat_unlock();
@@ -1030,7 +1030,7 @@ static void part_round_stats_single(int cpu, struct hd_struct *part,
 
         if (part->in_flight) {
                 __part_stat_add(cpu, part, time_in_queue,
-                                part->in_flight * (now - part->stamp));
+                                part_in_flight(part) * (now - part->stamp));
                 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
         }
         part->stamp = now;
@@ -1737,7 +1737,7 @@ static void blk_account_io_done(struct request *req)
                 part_stat_inc(cpu, part, ios[rw]);
                 part_stat_add(cpu, part, ticks[rw], duration);
                 part_round_stats(cpu, part);
-                part_dec_in_flight(part);
+                part_dec_in_flight(part, rw);
 
                 part_stat_unlock();
         }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b0de8574fdc8..99cb5cf1f447 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -351,7 +351,7 @@ static void blk_account_io_merge(struct request *req)
                 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
 
                 part_round_stats(cpu, part);
-                part_dec_in_flight(part);
+                part_dec_in_flight(part, rq_data_dir(req));
 
                 part_stat_unlock();
         }
diff --git a/block/genhd.c b/block/genhd.c
index b89328eceee2..5b76bf55d05c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -869,6 +869,7 @@ static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
 static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
 static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
 static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
+static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 static struct device_attribute dev_attr_fail =
         __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
@@ -888,6 +889,7 @@ static struct attribute *disk_attrs[] = {
         &dev_attr_alignment_offset.attr,
         &dev_attr_capability.attr,
         &dev_attr_stat.attr,
+        &dev_attr_inflight.attr,
 #ifdef CONFIG_FAIL_MAKE_REQUEST
         &dev_attr_fail.attr,
 #endif
@@ -1053,7 +1055,7 @@ static int diskstats_show(struct seq_file *seqf, void *v)
                            part_stat_read(hd, merges[1]),
                            (unsigned long long)part_stat_read(hd, sectors[1]),
                            jiffies_to_msecs(part_stat_read(hd, ticks[1])),
-                           hd->in_flight,
+                           part_in_flight(hd),
                            jiffies_to_msecs(part_stat_read(hd, io_ticks)),
                            jiffies_to_msecs(part_stat_read(hd, time_in_queue))
                         );