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Subject[PATCH] block: describe difference between flags IO_STAT and STATS
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This adds reasonable comments, but they definitely needs better names.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
include/linux/blkdev.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6980014357d4..4f8440dc469b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -108,7 +108,7 @@ typedef __u32 __bitwise req_flags_t;
#define RQF_QUIET ((__force req_flags_t)(1 << 11))
/* elevator private data attached */
#define RQF_ELVPRIV ((__force req_flags_t)(1 << 12))
-/* account I/O stat */
+/* account into disk and partition IO statistics */
#define RQF_IO_STAT ((__force req_flags_t)(1 << 13))
/* request came from our alloc pool */
#define RQF_ALLOCED ((__force req_flags_t)(1 << 14))
@@ -116,7 +116,7 @@ typedef __u32 __bitwise req_flags_t;
#define RQF_PM ((__force req_flags_t)(1 << 15))
/* on IO scheduler merge hash */
#define RQF_HASHED ((__force req_flags_t)(1 << 16))
-/* IO stats tracking on */
+/* track IO completion time */
#define RQF_STATS ((__force req_flags_t)(1 << 17))
/* Look at ->special_vec for the actual data payload instead of the
bio chain. */
@@ -679,7 +679,7 @@ struct request_queue {
#define QUEUE_FLAG_FAIL_IO 7 /* fake timeout */
#define QUEUE_FLAG_NONROT 9 /* non-rotational device (SSD) */
#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
-#define QUEUE_FLAG_IO_STAT 10 /* do IO stats */
+#define QUEUE_FLAG_IO_STAT 10 /* do disk/partitions IO accounting */
#define QUEUE_FLAG_DISCARD 11 /* supports DISCARD */
#define QUEUE_FLAG_NOXMERGES 12 /* No extended merges */
#define QUEUE_FLAG_ADD_RANDOM 13 /* Contributes to random pool */
@@ -693,7 +693,7 @@ struct request_queue {
#define QUEUE_FLAG_FUA 21 /* device supports FUA writes */
#define QUEUE_FLAG_FLUSH_NQ 22 /* flush not queueuable */
#define QUEUE_FLAG_DAX 23 /* device supports DAX */
-#define QUEUE_FLAG_STATS 24 /* track rq completion times */
+#define QUEUE_FLAG_STATS 24 /* track IO start and completion times */
#define QUEUE_FLAG_POLL_STATS 25 /* collecting stats for hybrid polling */
#define QUEUE_FLAG_REGISTERED 26 /* queue has been registered to a disk */
#define QUEUE_FLAG_SCSI_PASSTHROUGH 27 /* queue supports SCSI commands */
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