for-linus-20180922

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Merge tag 'for-linus-20180922' of git://git.kernel.dk/linux-block

Jens writes:
  "Just a single fix in this pull request, fixing a regression in
  /proc/diskstats caused by the unification of timestamps."

* tag 'for-linus-20180922' of git://git.kernel.dk/linux-block:
  block: use nanosecond resolution for iostat

block/bio.c

@@ -1684,7 +1684,7 @@ void generic_end_io_acct(struct request_queue *q, int req_op,
 	const int sgrp = op_stat_group(req_op);
 	int cpu = part_stat_lock();
 
-	part_stat_add(cpu, part, ticks[sgrp], duration);
+	part_stat_add(cpu, part, nsecs[sgrp], jiffies_to_nsecs(duration));
 	part_round_stats(q, cpu, part);
 	part_dec_in_flight(q, part, op_is_write(req_op));
 

block/blk-core.c

@@ -2733,17 +2733,15 @@ void blk_account_io_done(struct request *req, u64 now)
 	 * containing request is enough.
 	 */
 	if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
-		unsigned long duration;
 		const int sgrp = op_stat_group(req_op(req));
 		struct hd_struct *part;
 		int cpu;
 
-		duration = nsecs_to_jiffies(now - req->start_time_ns);
 		cpu = part_stat_lock();
 		part = req->part;
 
 		part_stat_inc(cpu, part, ios[sgrp]);
-		part_stat_add(cpu, part, ticks[sgrp], duration);
+		part_stat_add(cpu, part, nsecs[sgrp], now - req->start_time_ns);
 		part_round_stats(req->q, cpu, part);
 		part_dec_in_flight(req->q, part, rq_data_dir(req));
 

block/genhd.c

@@ -1343,18 +1343,18 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 			   part_stat_read(hd, ios[STAT_READ]),
 			   part_stat_read(hd, merges[STAT_READ]),
 			   part_stat_read(hd, sectors[STAT_READ]),
-			   jiffies_to_msecs(part_stat_read(hd, ticks[STAT_READ])),
+			   (unsigned int)part_stat_read_msecs(hd, STAT_READ),
 			   part_stat_read(hd, ios[STAT_WRITE]),
 			   part_stat_read(hd, merges[STAT_WRITE]),
 			   part_stat_read(hd, sectors[STAT_WRITE]),
-			   jiffies_to_msecs(part_stat_read(hd, ticks[STAT_WRITE])),
+			   (unsigned int)part_stat_read_msecs(hd, STAT_WRITE),
 			   inflight[0],
 			   jiffies_to_msecs(part_stat_read(hd, io_ticks)),
 			   jiffies_to_msecs(part_stat_read(hd, time_in_queue)),
 			   part_stat_read(hd, ios[STAT_DISCARD]),
 			   part_stat_read(hd, merges[STAT_DISCARD]),
 			   part_stat_read(hd, sectors[STAT_DISCARD]),
-			   jiffies_to_msecs(part_stat_read(hd, ticks[STAT_DISCARD]))
+			   (unsigned int)part_stat_read_msecs(hd, STAT_DISCARD)
 			);
 	}
 	disk_part_iter_exit(&piter);

block/partition-generic.c

@@ -136,18 +136,18 @@ ssize_t part_stat_show(struct device *dev,
 		part_stat_read(p, ios[STAT_READ]),
 		part_stat_read(p, merges[STAT_READ]),
 		(unsigned long long)part_stat_read(p, sectors[STAT_READ]),
-		jiffies_to_msecs(part_stat_read(p, ticks[STAT_READ])),
+		(unsigned int)part_stat_read_msecs(p, STAT_READ),
 		part_stat_read(p, ios[STAT_WRITE]),
 		part_stat_read(p, merges[STAT_WRITE]),
 		(unsigned long long)part_stat_read(p, sectors[STAT_WRITE]),
-		jiffies_to_msecs(part_stat_read(p, ticks[STAT_WRITE])),
+		(unsigned int)part_stat_read_msecs(p, STAT_WRITE),
 		inflight[0],
 		jiffies_to_msecs(part_stat_read(p, io_ticks)),
 		jiffies_to_msecs(part_stat_read(p, time_in_queue)),
 		part_stat_read(p, ios[STAT_DISCARD]),
 		part_stat_read(p, merges[STAT_DISCARD]),
 		(unsigned long long)part_stat_read(p, sectors[STAT_DISCARD]),
-		jiffies_to_msecs(part_stat_read(p, ticks[STAT_DISCARD])));
+		(unsigned int)part_stat_read_msecs(p, STAT_DISCARD));
 }
 
 ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,

include/linux/genhd.h

@@ -83,10 +83,10 @@ struct partition {
 } __attribute__((packed));
 
 struct disk_stats {
+	u64 nsecs[NR_STAT_GROUPS];
 	unsigned long sectors[NR_STAT_GROUPS];
 	unsigned long ios[NR_STAT_GROUPS];
 	unsigned long merges[NR_STAT_GROUPS];
-	unsigned long ticks[NR_STAT_GROUPS];
 	unsigned long io_ticks;
 	unsigned long time_in_queue;
 };
@@ -354,6 +354,9 @@ static inline void free_part_stats(struct hd_struct *part)
 
 #endif /* CONFIG_SMP */
 
+#define part_stat_read_msecs(part, which)				\
+	div_u64(part_stat_read(part, nsecs[which]), NSEC_PER_MSEC)
+
 #define part_stat_read_accum(part, field)				\
 	(part_stat_read(part, field[STAT_READ]) +			\
 	 part_stat_read(part, field[STAT_WRITE]) +			\