[PATCH v3 0/9] md: fix is_mddev_idle()

[PATCH v3 0/9] md: fix is_mddev_idle()

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Changes in v3:
 - add review tag for patch 1-5;
 - fix some typo and words;
Changes in v2:
 - add patch 1-5;
 - add reviewed-by in patch 6,7,9;
 - rename mddev->last_events to mddev->normal_IO_events in patch 8;

Yu Kuai (9):
  blk-mq: remove blk_mq_in_flight()
  block: reuse part_in_flight_rw for part_in_flight
  block: WARN if bdev inflight counter is negative
  block: clean up blk_mq_in_flight_rw()
  block: export API to get the number of bdev inflight IO
  md: record dm-raid gendisk in mddev
  md: add a new api sync_io_depth
  md: fix is_mddev_idle()
  md: clean up accounting for issued sync IO

 block/blk-core.c          |   2 +-
 block/blk-mq.c            |  22 ++---
 block/blk-mq.h            |   5 +-
 block/blk.h               |   1 -
 block/genhd.c             |  69 ++++++++------
 drivers/md/dm-raid.c      |   3 +
 drivers/md/md.c           | 190 ++++++++++++++++++++++++++------------
 drivers/md/md.h           |  18 +---
 drivers/md/raid1.c        |   3 -
 drivers/md/raid10.c       |   9 --
 drivers/md/raid5.c        |   8 --
 include/linux/blkdev.h    |   1 -
 include/linux/part_stat.h |   2 +
 13 files changed, 191 insertions(+), 142 deletions(-)

-- 
2.39.2

[PATCH v3 1/9] blk-mq: remove blk_mq_in_flight()

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

After commit 7be835694dae ("block: fix that util can be greater than
100%"), it's not used and can be removed.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-mq.c | 10 ----------
 block/blk-mq.h |  2 --
 2 files changed, 12 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 83c651a7facd..45989960a89d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -101,16 +101,6 @@ static bool blk_mq_check_inflight(struct request *rq, void *priv)
 	return true;
 }
 
-unsigned int blk_mq_in_flight(struct request_queue *q,
-		struct block_device *part)
-{
-	struct mq_inflight mi = { .part = part };
-
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
-
-	return mi.inflight[0] + mi.inflight[1];
-}
-
 void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
 		unsigned int inflight[2])
 {
diff --git a/block/blk-mq.h b/block/blk-mq.h
index d15ff1e130c8..eeac0d47c878 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -246,8 +246,6 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
 	return hctx->nr_ctx && hctx->tags;
 }
 
-unsigned int blk_mq_in_flight(struct request_queue *q,
-		struct block_device *part);
 void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
 		unsigned int inflight[2]);
 
-- 
2.39.2

[PATCH v3 2/9] block: reuse part_in_flight_rw for part_in_flight

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

They are almost identical, to make code cleaner.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 block/genhd.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index c2bd86cd09de..f671d9ee00c4 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -125,21 +125,6 @@ static void part_stat_read_all(struct block_device *part,
 	}
 }
 
-unsigned int part_in_flight(struct block_device *part)
-{
-	unsigned int inflight = 0;
-	int cpu;
-
-	for_each_possible_cpu(cpu) {
-		inflight += part_stat_local_read_cpu(part, in_flight[0], cpu) +
-			    part_stat_local_read_cpu(part, in_flight[1], cpu);
-	}
-	if ((int)inflight < 0)
-		inflight = 0;
-
-	return inflight;
-}
-
 static void part_in_flight_rw(struct block_device *part,
 		unsigned int inflight[2])
 {
@@ -157,6 +142,15 @@ static void part_in_flight_rw(struct block_device *part,
 		inflight[1] = 0;
 }
 
+unsigned int part_in_flight(struct block_device *part)
+{
+	unsigned int inflight[2];
+
+	part_in_flight_rw(part, inflight);
+
+	return inflight[READ] + inflight[WRITE];
+}
+
 /*
  * Can be deleted altogether. Later.
  *
-- 
2.39.2

[PATCH v3 3/9] block: WARN if bdev inflight counter is negative

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Which means there is a bug for related bio-based disk driver, or blk-mq
for rq-based disk, it's better not to hide the bug.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 block/genhd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index f671d9ee00c4..d158c25237b6 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -136,9 +136,9 @@ static void part_in_flight_rw(struct block_device *part,
 		inflight[0] += part_stat_local_read_cpu(part, in_flight[0], cpu);
 		inflight[1] += part_stat_local_read_cpu(part, in_flight[1], cpu);
 	}
-	if ((int)inflight[0] < 0)
+	if (WARN_ON_ONCE((int)inflight[0] < 0))
 		inflight[0] = 0;
-	if ((int)inflight[1] < 0)
+	if (WARN_ON_ONCE((int)inflight[1] < 0))
 		inflight[1] = 0;
 }
 
-- 
2.39.2

[PATCH v3 4/9] block: clean up blk_mq_in_flight_rw()

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Also add comment for part_inflight_show() for the difference between
bio-based and rq-based device.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-mq.c | 12 ++++++------
 block/blk-mq.h |  3 +--
 block/genhd.c  | 43 +++++++++++++++++++++++++------------------
 3 files changed, 32 insertions(+), 26 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 45989960a89d..4722a4ad4121 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -89,7 +89,7 @@ struct mq_inflight {
 	unsigned int inflight[2];
 };
 
-static bool blk_mq_check_inflight(struct request *rq, void *priv)
+static bool blk_mq_check_in_driver(struct request *rq, void *priv)
 {
 	struct mq_inflight *mi = priv;
 
@@ -101,14 +101,14 @@ static bool blk_mq_check_inflight(struct request *rq, void *priv)
 	return true;
 }
 
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2])
+void blk_mq_in_driver_rw(struct block_device *part, unsigned int inflight[2])
 {
 	struct mq_inflight mi = { .part = part };
 
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
-	inflight[0] = mi.inflight[0];
-	inflight[1] = mi.inflight[1];
+	blk_mq_queue_tag_busy_iter(bdev_get_queue(part), blk_mq_check_in_driver,
+				   &mi);
+	inflight[READ] = mi.inflight[READ];
+	inflight[WRITE] = mi.inflight[WRITE];
 }
 
 #ifdef CONFIG_LOCKDEP
diff --git a/block/blk-mq.h b/block/blk-mq.h
index eeac0d47c878..affb2e14b56e 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -246,8 +246,7 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
 	return hctx->nr_ctx && hctx->tags;
 }
 
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2]);
+void blk_mq_in_driver_rw(struct block_device *part, unsigned int inflight[2]);
 
 static inline void blk_mq_put_dispatch_budget(struct request_queue *q,
 					      int budget_token)
diff --git a/block/genhd.c b/block/genhd.c
index d158c25237b6..2470099b492b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -126,27 +126,32 @@ static void part_stat_read_all(struct block_device *part,
 }
 
 static void part_in_flight_rw(struct block_device *part,
-		unsigned int inflight[2])
+		unsigned int inflight[2], bool mq_driver)
 {
 	int cpu;
 
-	inflight[0] = 0;
-	inflight[1] = 0;
-	for_each_possible_cpu(cpu) {
-		inflight[0] += part_stat_local_read_cpu(part, in_flight[0], cpu);
-		inflight[1] += part_stat_local_read_cpu(part, in_flight[1], cpu);
+	if (mq_driver) {
+		blk_mq_in_driver_rw(part, inflight);
+	} else {
+		for_each_possible_cpu(cpu) {
+			inflight[READ] += part_stat_local_read_cpu(
+						part, in_flight[READ], cpu);
+			inflight[WRITE] += part_stat_local_read_cpu(
+						part, in_flight[WRITE], cpu);
+		}
 	}
-	if (WARN_ON_ONCE((int)inflight[0] < 0))
-		inflight[0] = 0;
-	if (WARN_ON_ONCE((int)inflight[1] < 0))
-		inflight[1] = 0;
+
+	if (WARN_ON_ONCE((int)inflight[READ] < 0))
+		inflight[READ] = 0;
+	if (WARN_ON_ONCE((int)inflight[WRITE] < 0))
+		inflight[WRITE] = 0;
 }
 
 unsigned int part_in_flight(struct block_device *part)
 {
-	unsigned int inflight[2];
+	unsigned int inflight[2] = {0};
 
-	part_in_flight_rw(part, inflight);
+	part_in_flight_rw(part, inflight, false);
 
 	return inflight[READ] + inflight[WRITE];
 }
@@ -1036,19 +1041,21 @@ ssize_t part_stat_show(struct device *dev,
 		(unsigned int)div_u64(stat.nsecs[STAT_FLUSH], NSEC_PER_MSEC));
 }
 
+/*
+ * Show the number of IOs issued to driver.
+ * For bio-based device, started from bdev_start_io_acct();
+ * For rq-based device, started from blk_mq_start_request();
+ */
 ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
 	struct block_device *bdev = dev_to_bdev(dev);
 	struct request_queue *q = bdev_get_queue(bdev);
-	unsigned int inflight[2];
+	unsigned int inflight[2] = {0};
 
-	if (queue_is_mq(q))
-		blk_mq_in_flight_rw(q, bdev, inflight);
-	else
-		part_in_flight_rw(bdev, inflight);
+	part_in_flight_rw(bdev, inflight, queue_is_mq(q));
 
-	return sysfs_emit(buf, "%8u %8u\n", inflight[0], inflight[1]);
+	return sysfs_emit(buf, "%8u %8u\n", inflight[READ], inflight[WRITE]);
 }
 
 static ssize_t disk_capability_show(struct device *dev,
-- 
2.39.2

[PATCH 4/9] block: cleanup blk_mq_in_flight_rw()

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Also add comment for part_inflight_show() for the difference between
bio-based and rq-based device.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 block/blk-mq.c | 12 ++++++------
 block/blk-mq.h |  3 +--
 block/genhd.c  | 43 +++++++++++++++++++++++++------------------
 3 files changed, 32 insertions(+), 26 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 301dbd3e1743..0067e8226e05 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -89,7 +89,7 @@ struct mq_inflight {
 	unsigned int inflight[2];
 };
 
-static bool blk_mq_check_inflight(struct request *rq, void *priv)
+static bool blk_mq_check_in_driver(struct request *rq, void *priv)
 {
 	struct mq_inflight *mi = priv;
 
@@ -101,14 +101,14 @@ static bool blk_mq_check_inflight(struct request *rq, void *priv)
 	return true;
 }
 
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2])
+void blk_mq_in_driver_rw(struct block_device *part, unsigned int inflight[2])
 {
 	struct mq_inflight mi = { .part = part };
 
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
-	inflight[0] = mi.inflight[0];
-	inflight[1] = mi.inflight[1];
+	blk_mq_queue_tag_busy_iter(bdev_get_queue(part), blk_mq_check_in_driver,
+				   &mi);
+	inflight[READ] = mi.inflight[READ];
+	inflight[WRITE] = mi.inflight[WRITE];
 }
 
 #ifdef CONFIG_LOCKDEP
diff --git a/block/blk-mq.h b/block/blk-mq.h
index a23d5812d08f..4205da1a4836 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -246,8 +246,7 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
 	return hctx->nr_ctx && hctx->tags;
 }
 
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2]);
+void blk_mq_in_driver_rw(struct block_device *part, unsigned int inflight[2]);
 
 static inline void blk_mq_put_dispatch_budget(struct request_queue *q,
 					      int budget_token)
diff --git a/block/genhd.c b/block/genhd.c
index d158c25237b6..2470099b492b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -126,27 +126,32 @@ static void part_stat_read_all(struct block_device *part,
 }
 
 static void part_in_flight_rw(struct block_device *part,
-		unsigned int inflight[2])
+		unsigned int inflight[2], bool mq_driver)
 {
 	int cpu;
 
-	inflight[0] = 0;
-	inflight[1] = 0;
-	for_each_possible_cpu(cpu) {
-		inflight[0] += part_stat_local_read_cpu(part, in_flight[0], cpu);
-		inflight[1] += part_stat_local_read_cpu(part, in_flight[1], cpu);
+	if (mq_driver) {
+		blk_mq_in_driver_rw(part, inflight);
+	} else {
+		for_each_possible_cpu(cpu) {
+			inflight[READ] += part_stat_local_read_cpu(
+						part, in_flight[READ], cpu);
+			inflight[WRITE] += part_stat_local_read_cpu(
+						part, in_flight[WRITE], cpu);
+		}
 	}
-	if (WARN_ON_ONCE((int)inflight[0] < 0))
-		inflight[0] = 0;
-	if (WARN_ON_ONCE((int)inflight[1] < 0))
-		inflight[1] = 0;
+
+	if (WARN_ON_ONCE((int)inflight[READ] < 0))
+		inflight[READ] = 0;
+	if (WARN_ON_ONCE((int)inflight[WRITE] < 0))
+		inflight[WRITE] = 0;
 }
 
 unsigned int part_in_flight(struct block_device *part)
 {
-	unsigned int inflight[2];
+	unsigned int inflight[2] = {0};
 
-	part_in_flight_rw(part, inflight);
+	part_in_flight_rw(part, inflight, false);
 
 	return inflight[READ] + inflight[WRITE];
 }
@@ -1036,19 +1041,21 @@ ssize_t part_stat_show(struct device *dev,
 		(unsigned int)div_u64(stat.nsecs[STAT_FLUSH], NSEC_PER_MSEC));
 }
 
+/*
+ * Show the number of IOs issued to driver.
+ * For bio-based device, started from bdev_start_io_acct();
+ * For rq-based device, started from blk_mq_start_request();
+ */
 ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
 	struct block_device *bdev = dev_to_bdev(dev);
 	struct request_queue *q = bdev_get_queue(bdev);
-	unsigned int inflight[2];
+	unsigned int inflight[2] = {0};
 
-	if (queue_is_mq(q))
-		blk_mq_in_flight_rw(q, bdev, inflight);
-	else
-		part_in_flight_rw(bdev, inflight);
+	part_in_flight_rw(bdev, inflight, queue_is_mq(q));
 
-	return sysfs_emit(buf, "%8u %8u\n", inflight[0], inflight[1]);
+	return sysfs_emit(buf, "%8u %8u\n", inflight[READ], inflight[WRITE]);
 }
 
 static ssize_t disk_capability_show(struct device *dev,
-- 
2.39.2

[PATCH v3 5/9] block: export API to get the number of bdev inflight IO

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

- rename part_in_{flight, flight_rw} to bdev_count_{inflight, inflight_rw}
- export bdev_count_inflight, to fix a problem in mdraid that foreground
  IO can be starved by background sync IO in later patches

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-core.c          |  2 +-
 block/blk.h               |  1 -
 block/genhd.c             | 22 ++++++++++++++++------
 include/linux/part_stat.h |  2 ++
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index e8cc270a453f..b862c66018f2 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1018,7 +1018,7 @@ void update_io_ticks(struct block_device *part, unsigned long now, bool end)
 	stamp = READ_ONCE(part->bd_stamp);
 	if (unlikely(time_after(now, stamp)) &&
 	    likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) &&
-	    (end || part_in_flight(part)))
+	    (end || bdev_count_inflight(part)))
 		__part_stat_add(part, io_ticks, now - stamp);
 
 	if (bdev_is_partition(part)) {
diff --git a/block/blk.h b/block/blk.h
index ff21f234b62f..c5a18f0fd3a9 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -421,7 +421,6 @@ void blk_apply_bdi_limits(struct backing_dev_info *bdi,
 int blk_dev_init(void);
 
 void update_io_ticks(struct block_device *part, unsigned long now, bool end);
-unsigned int part_in_flight(struct block_device *part);
 
 static inline void req_set_nomerge(struct request_queue *q, struct request *req)
 {
diff --git a/block/genhd.c b/block/genhd.c
index 2470099b492b..fdaeafddfc4c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -125,7 +125,7 @@ static void part_stat_read_all(struct block_device *part,
 	}
 }
 
-static void part_in_flight_rw(struct block_device *part,
+static void bdev_count_inflight_rw(struct block_device *part,
 		unsigned int inflight[2], bool mq_driver)
 {
 	int cpu;
@@ -147,14 +147,24 @@ static void part_in_flight_rw(struct block_device *part,
 		inflight[WRITE] = 0;
 }
 
-unsigned int part_in_flight(struct block_device *part)
+/**
+ * bdev_count_inflight - get the number of inflight IOs for a block device.
+ *
+ * @part: the block device.
+ *
+ * Inflight here means started IO accounting, from bdev_start_io_acct() for
+ * bio-based block device, and from blk_account_io_start() for rq-based block
+ * device.
+ */
+unsigned int bdev_count_inflight(struct block_device *part)
 {
 	unsigned int inflight[2] = {0};
 
-	part_in_flight_rw(part, inflight, false);
+	bdev_count_inflight_rw(part, inflight, false);
 
 	return inflight[READ] + inflight[WRITE];
 }
+EXPORT_SYMBOL_GPL(bdev_count_inflight);
 
 /*
  * Can be deleted altogether. Later.
@@ -1004,7 +1014,7 @@ ssize_t part_stat_show(struct device *dev,
 	struct disk_stats stat;
 	unsigned int inflight;
 
-	inflight = part_in_flight(bdev);
+	inflight = bdev_count_inflight(bdev);
 	if (inflight) {
 		part_stat_lock();
 		update_io_ticks(bdev, jiffies, true);
@@ -1053,7 +1063,7 @@ ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
 	struct request_queue *q = bdev_get_queue(bdev);
 	unsigned int inflight[2] = {0};
 
-	part_in_flight_rw(bdev, inflight, queue_is_mq(q));
+	bdev_count_inflight_rw(bdev, inflight, queue_is_mq(q));
 
 	return sysfs_emit(buf, "%8u %8u\n", inflight[READ], inflight[WRITE]);
 }
@@ -1308,7 +1318,7 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 		if (bdev_is_partition(hd) && !bdev_nr_sectors(hd))
 			continue;
 
-		inflight = part_in_flight(hd);
+		inflight = bdev_count_inflight(hd);
 		if (inflight) {
 			part_stat_lock();
 			update_io_ticks(hd, jiffies, true);
diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index c5e9cac0575e..eeeff2a04529 100644
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -79,4 +79,6 @@ static inline void part_stat_set_all(struct block_device *part, int value)
 #define part_stat_local_read_cpu(part, field, cpu)			\
 	local_read(&(part_stat_get_cpu(part, field, cpu)))
 
+unsigned int bdev_count_inflight(struct block_device *part);
+
 #endif /* _LINUX_PART_STAT_H */
-- 
2.39.2

[PATCH v3 6/9] md: record dm-raid gendisk in mddev

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Following patch will use gendisk to check if there are normal IO
completed or inflight, to fix a problem in mdraid that foreground IO
can be starved by background sync IO in later patches.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
---
 drivers/md/dm-raid.c | 3 +++
 drivers/md/md.h      | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 6adc55fd90d3..127138c61be5 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -14,6 +14,7 @@
 #include "raid5.h"
 #include "raid10.h"
 #include "md-bitmap.h"
+#include "dm-core.h"
 
 #include <linux/device-mapper.h>
 
@@ -3308,6 +3309,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	/* Disable/enable discard support on raid set. */
 	configure_discard_support(rs);
+	rs->md.dm_gendisk = ti->table->md->disk;
 
 	mddev_unlock(&rs->md);
 	return 0;
@@ -3327,6 +3329,7 @@ static void raid_dtr(struct dm_target *ti)
 
 	mddev_lock_nointr(&rs->md);
 	md_stop(&rs->md);
+	rs->md.dm_gendisk = NULL;
 	mddev_unlock(&rs->md);
 
 	if (work_pending(&rs->md.event_work))
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1cf00a04bcdd..9d55b4630077 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -404,7 +404,8 @@ struct mddev {
 						       * are happening, so run/
 						       * takeover/stop are not safe
 						       */
-	struct gendisk			*gendisk;
+	struct gendisk			*gendisk;    /* mdraid gendisk */
+	struct gendisk			*dm_gendisk; /* dm-raid gendisk */
 
 	struct kobject			kobj;
 	int				hold_active;
-- 
2.39.2

[PATCH v3 7/9] md: add a new api sync_io_depth

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

Currently if sync speed is above speed_min and below speed_max,
md_do_sync() will wait for all sync IOs to be done before issuing new
sync IO, means sync IO depth is limited to just 1.

This limit is too low, in order to prevent sync speed drop conspicuously
after fixing is_mddev_idle() in the next patch, add a new api for
limiting sync IO depth, the default value is 32.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
---
 drivers/md/md.c | 109 +++++++++++++++++++++++++++++++++++++++---------
 drivers/md/md.h |   1 +
 2 files changed, 91 insertions(+), 19 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9daa78c5fe33..541151bcfe81 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -111,32 +111,48 @@ static void md_wakeup_thread_directly(struct md_thread __rcu *thread);
 /* Default safemode delay: 200 msec */
 #define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
 /*
- * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
- * is 1000 KB/sec, so the extra system load does not show up that much.
- * Increase it if you want to have more _guaranteed_ speed. Note that
- * the RAID driver will use the maximum available bandwidth if the IO
- * subsystem is idle. There is also an 'absolute maximum' reconstruction
- * speed limit - in case reconstruction slows down your system despite
- * idle IO detection.
+ * Current RAID-1,4,5,6,10 parallel reconstruction 'guaranteed speed limit'
+ * is sysctl_speed_limit_min, 1000 KB/sec by default, so the extra system load
+ * does not show up that much. Increase it if you want to have more guaranteed
+ * speed. Note that the RAID driver will use the maximum bandwidth
+ * sysctl_speed_limit_max, 200 MB/sec by default, if the IO subsystem is idle.
  *
- * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
- * or /sys/block/mdX/md/sync_speed_{min,max}
+ * Background sync IO speed control:
+ *
+ * - below speed min:
+ *   no limit;
+ * - above speed min and below speed max:
+ *   a) if mddev is idle, then no limit;
+ *   b) if mddev is busy handling normal IO, then limit inflight sync IO
+ *   to sync_io_depth;
+ * - above speed max:
+ *   sync IO can't be issued;
+ *
+ * Following configurations can be changed via /proc/sys/dev/raid/ for system
+ * or /sys/block/mdX/md/ for one array.
  */
-
 static int sysctl_speed_limit_min = 1000;
 static int sysctl_speed_limit_max = 200000;
-static inline int speed_min(struct mddev *mddev)
+static int sysctl_sync_io_depth = 32;
+
+static int speed_min(struct mddev *mddev)
 {
 	return mddev->sync_speed_min ?
 		mddev->sync_speed_min : sysctl_speed_limit_min;
 }
 
-static inline int speed_max(struct mddev *mddev)
+static int speed_max(struct mddev *mddev)
 {
 	return mddev->sync_speed_max ?
 		mddev->sync_speed_max : sysctl_speed_limit_max;
 }
 
+static int sync_io_depth(struct mddev *mddev)
+{
+	return mddev->sync_io_depth ?
+		mddev->sync_io_depth : sysctl_sync_io_depth;
+}
+
 static void rdev_uninit_serial(struct md_rdev *rdev)
 {
 	if (!test_and_clear_bit(CollisionCheck, &rdev->flags))
@@ -293,14 +309,21 @@ static const struct ctl_table raid_table[] = {
 		.procname	= "speed_limit_min",
 		.data		= &sysctl_speed_limit_min,
 		.maxlen		= sizeof(int),
-		.mode		= S_IRUGO|S_IWUSR,
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
 	{
 		.procname	= "speed_limit_max",
 		.data		= &sysctl_speed_limit_max,
 		.maxlen		= sizeof(int),
-		.mode		= S_IRUGO|S_IWUSR,
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "sync_io_depth",
+		.data		= &sysctl_sync_io_depth,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
 };
@@ -5091,7 +5114,7 @@ static ssize_t
 sync_min_show(struct mddev *mddev, char *page)
 {
 	return sprintf(page, "%d (%s)\n", speed_min(mddev),
-		       mddev->sync_speed_min ? "local": "system");
+		       mddev->sync_speed_min ? "local" : "system");
 }
 
 static ssize_t
@@ -5100,7 +5123,7 @@ sync_min_store(struct mddev *mddev, const char *buf, size_t len)
 	unsigned int min;
 	int rv;
 
-	if (strncmp(buf, "system", 6)==0) {
+	if (strncmp(buf, "system", 6) == 0) {
 		min = 0;
 	} else {
 		rv = kstrtouint(buf, 10, &min);
@@ -5120,7 +5143,7 @@ static ssize_t
 sync_max_show(struct mddev *mddev, char *page)
 {
 	return sprintf(page, "%d (%s)\n", speed_max(mddev),
-		       mddev->sync_speed_max ? "local": "system");
+		       mddev->sync_speed_max ? "local" : "system");
 }
 
 static ssize_t
@@ -5129,7 +5152,7 @@ sync_max_store(struct mddev *mddev, const char *buf, size_t len)
 	unsigned int max;
 	int rv;
 
-	if (strncmp(buf, "system", 6)==0) {
+	if (strncmp(buf, "system", 6) == 0) {
 		max = 0;
 	} else {
 		rv = kstrtouint(buf, 10, &max);
@@ -5145,6 +5168,35 @@ sync_max_store(struct mddev *mddev, const char *buf, size_t len)
 static struct md_sysfs_entry md_sync_max =
 __ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);
 
+static ssize_t
+sync_io_depth_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", sync_io_depth(mddev),
+		       mddev->sync_io_depth ? "local" : "system");
+}
+
+static ssize_t
+sync_io_depth_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int max;
+	int rv;
+
+	if (strncmp(buf, "system", 6) == 0) {
+		max = 0;
+	} else {
+		rv = kstrtouint(buf, 10, &max);
+		if (rv < 0)
+			return rv;
+		if (max == 0)
+			return -EINVAL;
+	}
+	mddev->sync_io_depth = max;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_io_depth =
+__ATTR_RW(sync_io_depth);
+
 static ssize_t
 degraded_show(struct mddev *mddev, char *page)
 {
@@ -5671,6 +5723,7 @@ static struct attribute *md_redundancy_attrs[] = {
 	&md_mismatches.attr,
 	&md_sync_min.attr,
 	&md_sync_max.attr,
+	&md_sync_io_depth.attr,
 	&md_sync_speed.attr,
 	&md_sync_force_parallel.attr,
 	&md_sync_completed.attr,
@@ -8927,6 +8980,23 @@ static sector_t md_sync_position(struct mddev *mddev, enum sync_action action)
 	}
 }
 
+static bool sync_io_within_limit(struct mddev *mddev)
+{
+	int io_sectors;
+
+	/*
+	 * For raid456, sync IO is stripe(4k) per IO, for other levels, it's
+	 * RESYNC_PAGES(64k) per IO.
+	 */
+	if (mddev->level == 4 || mddev->level == 5 || mddev->level == 6)
+		io_sectors = 8;
+	else
+		io_sectors = 128;
+
+	return atomic_read(&mddev->recovery_active) <
+		io_sectors * sync_io_depth(mddev);
+}
+
 #define SYNC_MARKS	10
 #define	SYNC_MARK_STEP	(3*HZ)
 #define UPDATE_FREQUENCY (5*60*HZ)
@@ -9195,7 +9265,8 @@ void md_do_sync(struct md_thread *thread)
 				msleep(500);
 				goto repeat;
 			}
-			if (!is_mddev_idle(mddev, 0)) {
+			if (!sync_io_within_limit(mddev) &&
+			    !is_mddev_idle(mddev, 0)) {
 				/*
 				 * Give other IO more of a chance.
 				 * The faster the devices, the less we wait.
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 9d55b4630077..b57842188f18 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -484,6 +484,7 @@ struct mddev {
 	/* if zero, use the system-wide default */
 	int				sync_speed_min;
 	int				sync_speed_max;
+	int				sync_io_depth;
 
 	/* resync even though the same disks are shared among md-devices */
 	int				parallel_resync;
-- 
2.39.2

[PATCH v3 8/9] md: fix is_mddev_idle()

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

If sync_speed is above speed_min, then is_mddev_idle() will be called
for each sync IO to check if the array is idle, and inflight sync_io
will be limited if the array is not idle.

However, while mkfs.ext4 for a large raid5 array while recovery is in
progress, it's found that sync_speed is already above speed_min while
lots of stripes are used for sync IO, causing long delay for mkfs.ext4.

Root cause is the following checking from is_mddev_idle():

t1: submit sync IO: events1 = completed IO - issued sync IO
t2: submit next sync IO: events2  = completed IO - issued sync IO
if (events2 - events1 > 64)

For consequence, the more sync IO issued, the less likely checking will
pass. And when completed normal IO is more than issued sync IO, the
condition will finally pass and is_mddev_idle() will return false,
however, last_events will be updated hence is_mddev_idle() can only
return false once in a while.

Fix this problem by changing the checking as following:

1) mddev doesn't have normal IO completed;
2) mddev doesn't have normal IO inflight;
3) if any member disks is partition, and all other partitions doesn't
   have IO completed.

Also change rdev->last_events to unsigned long to cleanup type casting.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 drivers/md/md.c | 81 ++++++++++++++++++++++++++-----------------------
 drivers/md/md.h |  3 +-
 2 files changed, 45 insertions(+), 39 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 541151bcfe81..0fde115e921f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8625,50 +8625,55 @@ void md_cluster_stop(struct mddev *mddev)
 	put_cluster_ops(mddev);
 }
 
-static int is_mddev_idle(struct mddev *mddev, int init)
+static bool is_rdev_holder_idle(struct md_rdev *rdev, bool init)
 {
+	unsigned long last_events = rdev->last_events;
+
+	if (!bdev_is_partition(rdev->bdev))
+		return true;
+
+	/*
+	 * If rdev is partition, and user doesn't issue IO to the array, the
+	 * array is still not idle if user issues IO to other partitions.
+	 */
+	rdev->last_events = part_stat_read_accum(rdev->bdev->bd_disk->part0,
+						 sectors) -
+			    part_stat_read_accum(rdev->bdev, sectors);
+
+	return init || rdev->last_events <= last_events;
+}
+
+/*
+ * mddev is idle if following conditions are matched since last check:
+ * 1) mddev doesn't have normal IO completed;
+ * 2) mddev doesn't have inflight normal IO;
+ * 3) if any member disk is partition, and other partitions don't have IO
+ *    completed;
+ *
+ * Noted this checking rely on IO accounting is enabled.
+ */
+static bool is_mddev_idle(struct mddev *mddev, int init)
+{
+	unsigned long last_events = mddev->normal_io_events;
+	struct gendisk *disk;
 	struct md_rdev *rdev;
-	int idle;
-	int curr_events;
+	bool idle = true;
 
-	idle = 1;
-	rcu_read_lock();
-	rdev_for_each_rcu(rdev, mddev) {
-		struct gendisk *disk = rdev->bdev->bd_disk;
+	disk = mddev_is_dm(mddev) ? mddev->dm_gendisk : mddev->gendisk;
+	if (!disk)
+		return true;
 
-		if (!init && !blk_queue_io_stat(disk->queue))
-			continue;
+	mddev->normal_io_events = part_stat_read_accum(disk->part0, sectors);
+	if (!init && (mddev->normal_io_events > last_events ||
+		      bdev_count_inflight(disk->part0)))
+		idle = false;
 
-		curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
-			      atomic_read(&disk->sync_io);
-		/* sync IO will cause sync_io to increase before the disk_stats
-		 * as sync_io is counted when a request starts, and
-		 * disk_stats is counted when it completes.
-		 * So resync activity will cause curr_events to be smaller than
-		 * when there was no such activity.
-		 * non-sync IO will cause disk_stat to increase without
-		 * increasing sync_io so curr_events will (eventually)
-		 * be larger than it was before.  Once it becomes
-		 * substantially larger, the test below will cause
-		 * the array to appear non-idle, and resync will slow
-		 * down.
-		 * If there is a lot of outstanding resync activity when
-		 * we set last_event to curr_events, then all that activity
-		 * completing might cause the array to appear non-idle
-		 * and resync will be slowed down even though there might
-		 * not have been non-resync activity.  This will only
-		 * happen once though.  'last_events' will soon reflect
-		 * the state where there is little or no outstanding
-		 * resync requests, and further resync activity will
-		 * always make curr_events less than last_events.
-		 *
-		 */
-		if (init || curr_events - rdev->last_events > 64) {
-			rdev->last_events = curr_events;
-			idle = 0;
-		}
-	}
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev)
+		if (!is_rdev_holder_idle(rdev, init))
+			idle = false;
 	rcu_read_unlock();
+
 	return idle;
 }
 
diff --git a/drivers/md/md.h b/drivers/md/md.h
index b57842188f18..1982f1f18627 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -132,7 +132,7 @@ struct md_rdev {
 
 	sector_t sectors;		/* Device size (in 512bytes sectors) */
 	struct mddev *mddev;		/* RAID array if running */
-	int last_events;		/* IO event timestamp */
+	unsigned long last_events;	/* IO event timestamp */
 
 	/*
 	 * If meta_bdev is non-NULL, it means that a separate device is
@@ -520,6 +520,7 @@ struct mddev {
 							 * adding a spare
 							 */
 
+	unsigned long			normal_io_events; /* IO event timestamp */
 	atomic_t			recovery_active; /* blocks scheduled, but not written */
 	wait_queue_head_t		recovery_wait;
 	sector_t			recovery_cp;
-- 
2.39.2

[PATCH v3 9/9] md: clean up accounting for issued sync IO

[Yu Kuai]

From: Yu Kuai <yukuai3@huawei.com>

It's no longer used and can be removed, also remove the field
'gendisk->sync_io'.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>
---
 drivers/md/md.h        | 11 -----------
 drivers/md/raid1.c     |  3 ---
 drivers/md/raid10.c    |  9 ---------
 drivers/md/raid5.c     |  8 --------
 include/linux/blkdev.h |  1 -
 5 files changed, 32 deletions(-)

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1982f1f18627..d45a9e6ead80 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -717,17 +717,6 @@ static inline int mddev_trylock(struct mddev *mddev)
 }
 extern void mddev_unlock(struct mddev *mddev);
 
-static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
-{
-	if (blk_queue_io_stat(bdev->bd_disk->queue))
-		atomic_add(nr_sectors, &bdev->bd_disk->sync_io);
-}
-
-static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
-{
-	md_sync_acct(bio->bi_bdev, nr_sectors);
-}
-
 struct md_personality
 {
 	struct md_submodule_head head;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index de9bccbe7337..657d481525be 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2382,7 +2382,6 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
 
 		wbio->bi_end_io = end_sync_write;
 		atomic_inc(&r1_bio->remaining);
-		md_sync_acct(conf->mirrors[i].rdev->bdev, bio_sectors(wbio));
 
 		submit_bio_noacct(wbio);
 	}
@@ -3055,7 +3054,6 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 			bio = r1_bio->bios[i];
 			if (bio->bi_end_io == end_sync_read) {
 				read_targets--;
-				md_sync_acct_bio(bio, nr_sectors);
 				if (read_targets == 1)
 					bio->bi_opf &= ~MD_FAILFAST;
 				submit_bio_noacct(bio);
@@ -3064,7 +3062,6 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 	} else {
 		atomic_set(&r1_bio->remaining, 1);
 		bio = r1_bio->bios[r1_bio->read_disk];
-		md_sync_acct_bio(bio, nr_sectors);
 		if (read_targets == 1)
 			bio->bi_opf &= ~MD_FAILFAST;
 		submit_bio_noacct(bio);
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index ba32bac975b8..dce06bf65016 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2426,7 +2426,6 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 
 		atomic_inc(&conf->mirrors[d].rdev->nr_pending);
 		atomic_inc(&r10_bio->remaining);
-		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(tbio));
 
 		if (test_bit(FailFast, &conf->mirrors[d].rdev->flags))
 			tbio->bi_opf |= MD_FAILFAST;
@@ -2448,8 +2447,6 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 			bio_copy_data(tbio, fbio);
 		d = r10_bio->devs[i].devnum;
 		atomic_inc(&r10_bio->remaining);
-		md_sync_acct(conf->mirrors[d].replacement->bdev,
-			     bio_sectors(tbio));
 		submit_bio_noacct(tbio);
 	}
 
@@ -2583,13 +2580,10 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 	d = r10_bio->devs[1].devnum;
 	if (wbio->bi_end_io) {
 		atomic_inc(&conf->mirrors[d].rdev->nr_pending);
-		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));
 		submit_bio_noacct(wbio);
 	}
 	if (wbio2) {
 		atomic_inc(&conf->mirrors[d].replacement->nr_pending);
-		md_sync_acct(conf->mirrors[d].replacement->bdev,
-			     bio_sectors(wbio2));
 		submit_bio_noacct(wbio2);
 	}
 }
@@ -3757,7 +3751,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		r10_bio->sectors = nr_sectors;
 
 		if (bio->bi_end_io == end_sync_read) {
-			md_sync_acct_bio(bio, nr_sectors);
 			bio->bi_status = 0;
 			submit_bio_noacct(bio);
 		}
@@ -4880,7 +4873,6 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
 	r10_bio->sectors = nr_sectors;
 
 	/* Now submit the read */
-	md_sync_acct_bio(read_bio, r10_bio->sectors);
 	atomic_inc(&r10_bio->remaining);
 	read_bio->bi_next = NULL;
 	submit_bio_noacct(read_bio);
@@ -4940,7 +4932,6 @@ static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 			continue;
 
 		atomic_inc(&rdev->nr_pending);
-		md_sync_acct_bio(b, r10_bio->sectors);
 		atomic_inc(&r10_bio->remaining);
 		b->bi_next = NULL;
 		submit_bio_noacct(b);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 6389383166c0..ca5b0e8ba707 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1240,10 +1240,6 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 		}
 
 		if (rdev) {
-			if (s->syncing || s->expanding || s->expanded
-			    || s->replacing)
-				md_sync_acct(rdev->bdev, RAID5_STRIPE_SECTORS(conf));
-
 			set_bit(STRIPE_IO_STARTED, &sh->state);
 
 			bio_init(bi, rdev->bdev, &dev->vec, 1, op | op_flags);
@@ -1300,10 +1296,6 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 				submit_bio_noacct(bi);
 		}
 		if (rrdev) {
-			if (s->syncing || s->expanding || s->expanded
-			    || s->replacing)
-				md_sync_acct(rrdev->bdev, RAID5_STRIPE_SECTORS(conf));
-
 			set_bit(STRIPE_IO_STARTED, &sh->state);
 
 			bio_init(rbi, rrdev->bdev, &dev->rvec, 1, op | op_flags);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5ccb961ee2ae..d3fab37e4daa 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -182,7 +182,6 @@ struct gendisk {
 	struct list_head slave_bdevs;
 #endif
 	struct timer_rand_state *random;
-	atomic_t sync_io;		/* RAID */
 	struct disk_events *ev;
 
 #ifdef CONFIG_BLK_DEV_ZONED
-- 
2.39.2

Re: [PATCH 4/9] block: cleanup blk_mq_in_flight_rw()

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v3 3/9] block: WARN if bdev inflight counter is negative

[John Garry]

On 06/05/2025 13:48, Yu Kuai wrote:
> From: Yu Kuai<yukuai3@huawei.com>
> 
> Which means there is a bug for related bio-based disk driver, or blk-mq
> for rq-based disk, it's better not to hide the bug.
> 
> Signed-off-by: Yu Kuai<yukuai3@huawei.com>
> Reviewed-by: Christoph Hellwig<hch@lst.de>
> Reviewed-by: Hannes Reinecke<hare@suse.de>

Reviewed-by: John Garry <john.g.garry@oracle.com>

Re: [PATCH v3 8/9] md: fix is_mddev_idle()

[Xiao Ni]

在 2025/5/6 下午8:49, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@huawei.com>
>
> If sync_speed is above speed_min, then is_mddev_idle() will be called
> for each sync IO to check if the array is idle, and inflight sync_io
> will be limited if the array is not idle.
>
> However, while mkfs.ext4 for a large raid5 array while recovery is in
> progress, it's found that sync_speed is already above speed_min while
> lots of stripes are used for sync IO, causing long delay for mkfs.ext4.
>
> Root cause is the following checking from is_mddev_idle():
>
> t1: submit sync IO: events1 = completed IO - issued sync IO
> t2: submit next sync IO: events2  = completed IO - issued sync IO
> if (events2 - events1 > 64)
>
> For consequence, the more sync IO issued, the less likely checking will
> pass. And when completed normal IO is more than issued sync IO, the
> condition will finally pass and is_mddev_idle() will return false,
> however, last_events will be updated hence is_mddev_idle() can only
> return false once in a while.
>
> Fix this problem by changing the checking as following:
>
> 1) mddev doesn't have normal IO completed;
> 2) mddev doesn't have normal IO inflight;
> 3) if any member disks is partition, and all other partitions doesn't
>     have IO completed.
>
> Also change rdev->last_events to unsigned long to cleanup type casting.
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>   drivers/md/md.c | 81 ++++++++++++++++++++++++++-----------------------
>   drivers/md/md.h |  3 +-
>   2 files changed, 45 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 541151bcfe81..0fde115e921f 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8625,50 +8625,55 @@ void md_cluster_stop(struct mddev *mddev)
>   	put_cluster_ops(mddev);
>   }
>   
> -static int is_mddev_idle(struct mddev *mddev, int init)
> +static bool is_rdev_holder_idle(struct md_rdev *rdev, bool init)
>   {
> +	unsigned long last_events = rdev->last_events;
> +
> +	if (!bdev_is_partition(rdev->bdev))
> +		return true;
> +
> +	/*
> +	 * If rdev is partition, and user doesn't issue IO to the array, the
> +	 * array is still not idle if user issues IO to other partitions.
> +	 */
> +	rdev->last_events = part_stat_read_accum(rdev->bdev->bd_disk->part0,
> +						 sectors) -
> +			    part_stat_read_accum(rdev->bdev, sectors);
> +
> +	return init || rdev->last_events <= last_events;
> +}
> +
> +/*
> + * mddev is idle if following conditions are matched since last check:
> + * 1) mddev doesn't have normal IO completed;
> + * 2) mddev doesn't have inflight normal IO;
> + * 3) if any member disk is partition, and other partitions don't have IO
> + *    completed;
> + *
> + * Noted this checking rely on IO accounting is enabled.
> + */
> +static bool is_mddev_idle(struct mddev *mddev, int init)
> +{
> +	unsigned long last_events = mddev->normal_io_events;
> +	struct gendisk *disk;
>   	struct md_rdev *rdev;
> -	int idle;
> -	int curr_events;
> +	bool idle = true;
>   
> -	idle = 1;
> -	rcu_read_lock();
> -	rdev_for_each_rcu(rdev, mddev) {
> -		struct gendisk *disk = rdev->bdev->bd_disk;
> +	disk = mddev_is_dm(mddev) ? mddev->dm_gendisk : mddev->gendisk;
> +	if (!disk)
> +		return true;
>   
> -		if (!init && !blk_queue_io_stat(disk->queue))
> -			continue;
> +	mddev->normal_io_events = part_stat_read_accum(disk->part0, sectors);
> +	if (!init && (mddev->normal_io_events > last_events ||
> +		      bdev_count_inflight(disk->part0)))
> +		idle = false;
>   
> -		curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
> -			      atomic_read(&disk->sync_io);
> -		/* sync IO will cause sync_io to increase before the disk_stats
> -		 * as sync_io is counted when a request starts, and
> -		 * disk_stats is counted when it completes.
> -		 * So resync activity will cause curr_events to be smaller than
> -		 * when there was no such activity.
> -		 * non-sync IO will cause disk_stat to increase without
> -		 * increasing sync_io so curr_events will (eventually)
> -		 * be larger than it was before.  Once it becomes
> -		 * substantially larger, the test below will cause
> -		 * the array to appear non-idle, and resync will slow
> -		 * down.
> -		 * If there is a lot of outstanding resync activity when
> -		 * we set last_event to curr_events, then all that activity
> -		 * completing might cause the array to appear non-idle
> -		 * and resync will be slowed down even though there might
> -		 * not have been non-resync activity.  This will only
> -		 * happen once though.  'last_events' will soon reflect
> -		 * the state where there is little or no outstanding
> -		 * resync requests, and further resync activity will
> -		 * always make curr_events less than last_events.
> -		 *
> -		 */
> -		if (init || curr_events - rdev->last_events > 64) {
> -			rdev->last_events = curr_events;
> -			idle = 0;
> -		}
> -	}
> +	rcu_read_lock();
> +	rdev_for_each_rcu(rdev, mddev)
> +		if (!is_rdev_holder_idle(rdev, init))
> +			idle = false;
>   	rcu_read_unlock();
> +
>   	return idle;
>   }
>   
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index b57842188f18..1982f1f18627 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -132,7 +132,7 @@ struct md_rdev {
>   
>   	sector_t sectors;		/* Device size (in 512bytes sectors) */
>   	struct mddev *mddev;		/* RAID array if running */
> -	int last_events;		/* IO event timestamp */
> +	unsigned long last_events;	/* IO event timestamp */
>   
>   	/*
>   	 * If meta_bdev is non-NULL, it means that a separate device is
> @@ -520,6 +520,7 @@ struct mddev {
>   							 * adding a spare
>   							 */
>   
> +	unsigned long			normal_io_events; /* IO event timestamp */
>   	atomic_t			recovery_active; /* blocks scheduled, but not written */
>   	wait_queue_head_t		recovery_wait;
>   	sector_t			recovery_cp;


Looks good to me

Reviewed-by: Xiao Ni <xni@redhat.com>