* [PATCH 1/3] Don't jump to compute_result state from check_result state
[not found] <20190329174617.3670341-1-songliubraving@fb.com>
@ 2019-03-29 17:46 ` Song Liu
2019-03-29 17:51 ` Jens Axboe
2019-03-29 17:46 ` [PATCH 2/3] Revert "MD: fix lock contention for flush bios" Song Liu
2019-03-29 17:46 ` [PATCH 3/3] md: batch flush requests Song Liu
2 siblings, 1 reply; 5+ messages in thread
From: Song Liu @ 2019-03-29 17:46 UTC (permalink / raw)
To: linux-raid, linux-block
Cc: kernel-team, neilb, xni, ncroxon, axboe, stable, David Jeffy,
Song Liu
From: Nigel Croxon <ncroxon@redhat.com>
Changing state from check_state_check_result to
check_state_compute_result not only is unsafe but also doesn't
appear to serve a valid purpose. A raid6 check should only be
pushing out extra writes if doing repair and a mis-match occurs.
The stripe dev management will already try and do repair writes
for failing sectors.
This patch makes the raid6 check_state_check_result handling
work more like raid5's. If somehow too many failures for a
check, just quit the check operation for the stripe. When any
checks pass, don't try and use check_state_compute_result for
a purpose it isn't needed for and is unsafe for. Just mark the
stripe as in sync for passing its parity checks and let the
stripe dev read/write code and the bad blocks list do their
job handling I/O errors.
Repro steps from Xiao:
These are the steps to reproduce this problem:
1. redefined OPT_MEDIUM_ERR_ADDR to 12000 in scsi_debug.c
2. insmod scsi_debug.ko dev_size_mb=11000 max_luns=1 num_tgts=1
3. mdadm --create /dev/md127 --level=6 --raid-devices=5 /dev/sde1 /dev/sde2 /dev/sde3 /dev/sde5 /dev/sde6
sde is the disk created by scsi_debug
4. echo "2" >/sys/module/scsi_debug/parameters/opts
5. raid-check
It panic:
[ 4854.730899] md: data-check of RAID array md127
[ 4854.857455] sd 5:0:0:0: [sdr] tag#80 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[ 4854.859246] sd 5:0:0:0: [sdr] tag#80 Sense Key : Medium Error [current]
[ 4854.860694] sd 5:0:0:0: [sdr] tag#80 Add. Sense: Unrecovered read error
[ 4854.862207] sd 5:0:0:0: [sdr] tag#80 CDB: Read(10) 28 00 00 00 2d 88 00 04 00 00
[ 4854.864196] print_req_error: critical medium error, dev sdr, sector 11656 flags 0
[ 4854.867409] sd 5:0:0:0: [sdr] tag#100 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[ 4854.869469] sd 5:0:0:0: [sdr] tag#100 Sense Key : Medium Error [current]
[ 4854.871206] sd 5:0:0:0: [sdr] tag#100 Add. Sense: Unrecovered read error
[ 4854.872858] sd 5:0:0:0: [sdr] tag#100 CDB: Read(10) 28 00 00 00 2e e0 00 00 08 00
[ 4854.874587] print_req_error: critical medium error, dev sdr, sector 12000 flags 4000
[ 4854.876456] sd 5:0:0:0: [sdr] tag#101 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[ 4854.878552] sd 5:0:0:0: [sdr] tag#101 Sense Key : Medium Error [current]
[ 4854.880278] sd 5:0:0:0: [sdr] tag#101 Add. Sense: Unrecovered read error
[ 4854.881846] sd 5:0:0:0: [sdr] tag#101 CDB: Read(10) 28 00 00 00 2e e8 00 00 08 00
[ 4854.883691] print_req_error: critical medium error, dev sdr, sector 12008 flags 4000
[ 4854.893927] sd 5:0:0:0: [sdr] tag#166 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[ 4854.896002] sd 5:0:0:0: [sdr] tag#166 Sense Key : Medium Error [current]
[ 4854.897561] sd 5:0:0:0: [sdr] tag#166 Add. Sense: Unrecovered read error
[ 4854.899110] sd 5:0:0:0: [sdr] tag#166 CDB: Read(10) 28 00 00 00 2e e0 00 00 10 00
[ 4854.900989] print_req_error: critical medium error, dev sdr, sector 12000 flags 0
[ 4854.902757] md/raid:md127: read error NOT corrected!! (sector 9952 on sdr1).
[ 4854.904375] md/raid:md127: read error NOT corrected!! (sector 9960 on sdr1).
[ 4854.906201] ------------[ cut here ]------------
[ 4854.907341] kernel BUG at drivers/md/raid5.c:4190!
raid5.c:4190 above is this BUG_ON:
handle_parity_checks6()
...
BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
Cc: <stable@vger.kernel.org> # v3.16+
OriginalAuthor: David Jeffery <djeffery@redhat.com>
Cc: Xiao Ni <xni@redhat.com>
Tested-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: David Jeffy <djeffery@redhat.com>
Signed-off-by: Nigel Croxon <ncroxon@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
drivers/md/raid5.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c033bfcb209e..4204a972ecf2 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4223,26 +4223,15 @@ static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
case check_state_check_result:
sh->check_state = check_state_idle;
+ if (s->failed > 1)
+ break;
/* handle a successful check operation, if parity is correct
* we are done. Otherwise update the mismatch count and repair
* parity if !MD_RECOVERY_CHECK
*/
if (sh->ops.zero_sum_result == 0) {
- /* both parities are correct */
- if (!s->failed)
- set_bit(STRIPE_INSYNC, &sh->state);
- else {
- /* in contrast to the raid5 case we can validate
- * parity, but still have a failure to write
- * back
- */
- sh->check_state = check_state_compute_result;
- /* Returning at this point means that we may go
- * off and bring p and/or q uptodate again so
- * we make sure to check zero_sum_result again
- * to verify if p or q need writeback
- */
- }
+ /* Any parity checked was correct */
+ set_bit(STRIPE_INSYNC, &sh->state);
} else {
atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery)) {
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 2/3] Revert "MD: fix lock contention for flush bios"
[not found] <20190329174617.3670341-1-songliubraving@fb.com>
2019-03-29 17:46 ` [PATCH 1/3] Don't jump to compute_result state from check_result state Song Liu
@ 2019-03-29 17:46 ` Song Liu
2019-03-29 17:46 ` [PATCH 3/3] md: batch flush requests Song Liu
2 siblings, 0 replies; 5+ messages in thread
From: Song Liu @ 2019-03-29 17:46 UTC (permalink / raw)
To: linux-raid, linux-block
Cc: kernel-team, neilb, xni, ncroxon, axboe, stable, Song Liu
From: NeilBrown <neilb@suse.com>
This reverts commit 5a409b4f56d50b212334f338cb8465d65550cd85.
This patch has two problems.
1/ it make multiple calls to submit_bio() from inside a make_request_fn.
The bios thus submitted will be queued on current->bio_list and not
submitted immediately. As the bios are allocated from a mempool,
this can theoretically result in a deadlock - all the pool of requests
could be in various ->bio_list queues and a subsequent mempool_alloc
could block waiting for one of them to be released.
2/ It aims to handle a case when there are many concurrent flush requests.
It handles this by submitting many requests in parallel - all of which
are identical and so most of which do nothing useful.
It would be more efficient to just send one lower-level request, but
allow that to satisfy multiple upper-level requests.
Fixes: 5a409b4f56d5 ("MD: fix lock contention for flush bios")
Cc: <stable@vger.kernel.org> # v4.19+
Tested-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
drivers/md/md.c | 159 +++++++++++++++++-------------------------------
drivers/md/md.h | 22 +++----
2 files changed, 62 insertions(+), 119 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 05ffffb8b769..021e522001c1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -132,24 +132,6 @@ static inline int speed_max(struct mddev *mddev)
mddev->sync_speed_max : sysctl_speed_limit_max;
}
-static void * flush_info_alloc(gfp_t gfp_flags, void *data)
-{
- return kzalloc(sizeof(struct flush_info), gfp_flags);
-}
-static void flush_info_free(void *flush_info, void *data)
-{
- kfree(flush_info);
-}
-
-static void * flush_bio_alloc(gfp_t gfp_flags, void *data)
-{
- return kzalloc(sizeof(struct flush_bio), gfp_flags);
-}
-static void flush_bio_free(void *flush_bio, void *data)
-{
- kfree(flush_bio);
-}
-
static struct ctl_table_header *raid_table_header;
static struct ctl_table raid_table[] = {
@@ -423,54 +405,30 @@ static int md_congested(void *data, int bits)
/*
* Generic flush handling for md
*/
-static void submit_flushes(struct work_struct *ws)
-{
- struct flush_info *fi = container_of(ws, struct flush_info, flush_work);
- struct mddev *mddev = fi->mddev;
- struct bio *bio = fi->bio;
-
- bio->bi_opf &= ~REQ_PREFLUSH;
- md_handle_request(mddev, bio);
-
- mempool_free(fi, mddev->flush_pool);
-}
-static void md_end_flush(struct bio *fbio)
+static void md_end_flush(struct bio *bio)
{
- struct flush_bio *fb = fbio->bi_private;
- struct md_rdev *rdev = fb->rdev;
- struct flush_info *fi = fb->fi;
- struct bio *bio = fi->bio;
- struct mddev *mddev = fi->mddev;
+ struct md_rdev *rdev = bio->bi_private;
+ struct mddev *mddev = rdev->mddev;
rdev_dec_pending(rdev, mddev);
- if (atomic_dec_and_test(&fi->flush_pending)) {
- if (bio->bi_iter.bi_size == 0) {
- /* an empty barrier - all done */
- bio_endio(bio);
- mempool_free(fi, mddev->flush_pool);
- } else {
- INIT_WORK(&fi->flush_work, submit_flushes);
- queue_work(md_wq, &fi->flush_work);
- }
+ if (atomic_dec_and_test(&mddev->flush_pending)) {
+ /* The pre-request flush has finished */
+ queue_work(md_wq, &mddev->flush_work);
}
-
- mempool_free(fb, mddev->flush_bio_pool);
- bio_put(fbio);
+ bio_put(bio);
}
-void md_flush_request(struct mddev *mddev, struct bio *bio)
+static void md_submit_flush_data(struct work_struct *ws);
+
+static void submit_flushes(struct work_struct *ws)
{
+ struct mddev *mddev = container_of(ws, struct mddev, flush_work);
struct md_rdev *rdev;
- struct flush_info *fi;
-
- fi = mempool_alloc(mddev->flush_pool, GFP_NOIO);
-
- fi->bio = bio;
- fi->mddev = mddev;
- atomic_set(&fi->flush_pending, 1);
+ INIT_WORK(&mddev->flush_work, md_submit_flush_data);
+ atomic_set(&mddev->flush_pending, 1);
rcu_read_lock();
rdev_for_each_rcu(rdev, mddev)
if (rdev->raid_disk >= 0 &&
@@ -480,40 +438,59 @@ void md_flush_request(struct mddev *mddev, struct bio *bio)
* we reclaim rcu_read_lock
*/
struct bio *bi;
- struct flush_bio *fb;
atomic_inc(&rdev->nr_pending);
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
-
- fb = mempool_alloc(mddev->flush_bio_pool, GFP_NOIO);
- fb->fi = fi;
- fb->rdev = rdev;
-
bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
- bio_set_dev(bi, rdev->bdev);
bi->bi_end_io = md_end_flush;
- bi->bi_private = fb;
+ bi->bi_private = rdev;
+ bio_set_dev(bi, rdev->bdev);
bi->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
-
- atomic_inc(&fi->flush_pending);
+ atomic_inc(&mddev->flush_pending);
submit_bio(bi);
-
rcu_read_lock();
rdev_dec_pending(rdev, mddev);
}
rcu_read_unlock();
+ if (atomic_dec_and_test(&mddev->flush_pending))
+ queue_work(md_wq, &mddev->flush_work);
+}
- if (atomic_dec_and_test(&fi->flush_pending)) {
- if (bio->bi_iter.bi_size == 0) {
- /* an empty barrier - all done */
- bio_endio(bio);
- mempool_free(fi, mddev->flush_pool);
- } else {
- INIT_WORK(&fi->flush_work, submit_flushes);
- queue_work(md_wq, &fi->flush_work);
- }
+static void md_submit_flush_data(struct work_struct *ws)
+{
+ struct mddev *mddev = container_of(ws, struct mddev, flush_work);
+ struct bio *bio = mddev->flush_bio;
+
+ /*
+ * must reset flush_bio before calling into md_handle_request to avoid a
+ * deadlock, because other bios passed md_handle_request suspend check
+ * could wait for this and below md_handle_request could wait for those
+ * bios because of suspend check
+ */
+ mddev->flush_bio = NULL;
+ wake_up(&mddev->sb_wait);
+
+ if (bio->bi_iter.bi_size == 0) {
+ /* an empty barrier - all done */
+ bio_endio(bio);
+ } else {
+ bio->bi_opf &= ~REQ_PREFLUSH;
+ md_handle_request(mddev, bio);
}
}
+
+void md_flush_request(struct mddev *mddev, struct bio *bio)
+{
+ spin_lock_irq(&mddev->lock);
+ wait_event_lock_irq(mddev->sb_wait,
+ !mddev->flush_bio,
+ mddev->lock);
+ mddev->flush_bio = bio;
+ spin_unlock_irq(&mddev->lock);
+
+ INIT_WORK(&mddev->flush_work, submit_flushes);
+ queue_work(md_wq, &mddev->flush_work);
+}
EXPORT_SYMBOL(md_flush_request);
static inline struct mddev *mddev_get(struct mddev *mddev)
@@ -560,6 +537,7 @@ void mddev_init(struct mddev *mddev)
atomic_set(&mddev->openers, 0);
atomic_set(&mddev->active_io, 0);
spin_lock_init(&mddev->lock);
+ atomic_set(&mddev->flush_pending, 0);
init_waitqueue_head(&mddev->sb_wait);
init_waitqueue_head(&mddev->recovery_wait);
mddev->reshape_position = MaxSector;
@@ -5511,22 +5489,6 @@ int md_run(struct mddev *mddev)
if (err)
return err;
}
- if (mddev->flush_pool == NULL) {
- mddev->flush_pool = mempool_create(NR_FLUSH_INFOS, flush_info_alloc,
- flush_info_free, mddev);
- if (!mddev->flush_pool) {
- err = -ENOMEM;
- goto abort;
- }
- }
- if (mddev->flush_bio_pool == NULL) {
- mddev->flush_bio_pool = mempool_create(NR_FLUSH_BIOS, flush_bio_alloc,
- flush_bio_free, mddev);
- if (!mddev->flush_bio_pool) {
- err = -ENOMEM;
- goto abort;
- }
- }
spin_lock(&pers_lock);
pers = find_pers(mddev->level, mddev->clevel);
@@ -5686,11 +5648,8 @@ int md_run(struct mddev *mddev)
return 0;
abort:
- mempool_destroy(mddev->flush_bio_pool);
- mddev->flush_bio_pool = NULL;
- mempool_destroy(mddev->flush_pool);
- mddev->flush_pool = NULL;
-
+ bioset_exit(&mddev->bio_set);
+ bioset_exit(&mddev->sync_set);
return err;
}
EXPORT_SYMBOL_GPL(md_run);
@@ -5894,14 +5853,6 @@ static void __md_stop(struct mddev *mddev)
mddev->to_remove = &md_redundancy_group;
module_put(pers->owner);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
- if (mddev->flush_bio_pool) {
- mempool_destroy(mddev->flush_bio_pool);
- mddev->flush_bio_pool = NULL;
- }
- if (mddev->flush_pool) {
- mempool_destroy(mddev->flush_pool);
- mddev->flush_pool = NULL;
- }
}
void md_stop(struct mddev *mddev)
diff --git a/drivers/md/md.h b/drivers/md/md.h
index c52afb52c776..2deb84fa93f9 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -252,19 +252,6 @@ enum mddev_sb_flags {
MD_SB_NEED_REWRITE, /* metadata write needs to be repeated */
};
-#define NR_FLUSH_INFOS 8
-#define NR_FLUSH_BIOS 64
-struct flush_info {
- struct bio *bio;
- struct mddev *mddev;
- struct work_struct flush_work;
- atomic_t flush_pending;
-};
-struct flush_bio {
- struct flush_info *fi;
- struct md_rdev *rdev;
-};
-
struct mddev {
void *private;
struct md_personality *pers;
@@ -470,8 +457,13 @@ struct mddev {
* metadata and bitmap writes
*/
- mempool_t *flush_pool;
- mempool_t *flush_bio_pool;
+ /* Generic flush handling.
+ * The last to finish preflush schedules a worker to submit
+ * the rest of the request (without the REQ_PREFLUSH flag).
+ */
+ struct bio *flush_bio;
+ atomic_t flush_pending;
+ struct work_struct flush_work;
struct work_struct event_work; /* used by dm to report failure event */
void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
struct md_cluster_info *cluster_info;
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 3/3] md: batch flush requests.
[not found] <20190329174617.3670341-1-songliubraving@fb.com>
2019-03-29 17:46 ` [PATCH 1/3] Don't jump to compute_result state from check_result state Song Liu
2019-03-29 17:46 ` [PATCH 2/3] Revert "MD: fix lock contention for flush bios" Song Liu
@ 2019-03-29 17:46 ` Song Liu
2 siblings, 0 replies; 5+ messages in thread
From: Song Liu @ 2019-03-29 17:46 UTC (permalink / raw)
To: linux-raid, linux-block
Cc: kernel-team, neilb, xni, ncroxon, axboe, stable, Song Liu
From: NeilBrown <neilb@suse.com>
Currently if many flush requests are submitted to an md device is quick
succession, they are serialized and can take a long to process them all.
We don't really need to call flush all those times - a single flush call
can satisfy all requests submitted before it started.
So keep track of when the current flush started and when it finished,
allow any pending flush that was requested before the flush started
to complete without waiting any more.
Test results from Xiao:
Test is done on a raid10 device which is created by 4 SSDs. The tool is
dbench.
1. The latest linux stable kernel
Operation Count AvgLat MaxLat
--------------------------------------------------
Deltree 768 10.509 78.305
Flush 2078376 0.013 10.094
Close 21787697 0.019 18.821
LockX 96580 0.007 3.184
Mkdir 384 0.008 0.062
Rename 1255883 0.191 23.534
ReadX 46495589 0.020 14.230
WriteX 14790591 7.123 60.706
Unlink 5989118 0.440 54.551
UnlockX 96580 0.005 2.736
FIND_FIRST 10393845 0.042 12.079
SET_FILE_INFORMATION 2415558 0.129 10.088
QUERY_FILE_INFORMATION 4711725 0.005 8.462
QUERY_PATH_INFORMATION 26883327 0.032 21.715
QUERY_FS_INFORMATION 4929409 0.010 8.238
NTCreateX 29660080 0.100 53.268
Throughput 1034.88 MB/sec (sync open) 128 clients 128 procs
max_latency=60.712 ms
2. With patch1 "Revert "MD: fix lock contention for flush bios""
Operation Count AvgLat MaxLat
--------------------------------------------------
Deltree 256 8.326 36.761
Flush 693291 3.974 180.269
Close 7266404 0.009 36.929
LockX 32160 0.006 0.840
Mkdir 128 0.008 0.021
Rename 418755 0.063 29.945
ReadX 15498708 0.007 7.216
WriteX 4932310 22.482 267.928
Unlink 1997557 0.109 47.553
UnlockX 32160 0.004 1.110
FIND_FIRST 3465791 0.036 7.320
SET_FILE_INFORMATION 805825 0.015 1.561
QUERY_FILE_INFORMATION 1570950 0.005 2.403
QUERY_PATH_INFORMATION 8965483 0.013 14.277
QUERY_FS_INFORMATION 1643626 0.009 3.314
NTCreateX 9892174 0.061 41.278
Throughput 345.009 MB/sec (sync open) 128 clients 128 procs
max_latency=267.939 m
3. With patch1 and patch2
Operation Count AvgLat MaxLat
--------------------------------------------------
Deltree 768 9.570 54.588
Flush 2061354 0.666 15.102
Close 21604811 0.012 25.697
LockX 95770 0.007 1.424
Mkdir 384 0.008 0.053
Rename 1245411 0.096 12.263
ReadX 46103198 0.011 12.116
WriteX 14667988 7.375 60.069
Unlink 5938936 0.173 30.905
UnlockX 95770 0.005 4.147
FIND_FIRST 10306407 0.041 11.715
SET_FILE_INFORMATION 2395987 0.048 7.640
QUERY_FILE_INFORMATION 4672371 0.005 9.291
QUERY_PATH_INFORMATION 26656735 0.018 19.719
QUERY_FS_INFORMATION 4887940 0.010 7.654
NTCreateX 29410811 0.059 28.551
Throughput 1026.21 MB/sec (sync open) 128 clients 128 procs
max_latency=60.075 ms
Cc: <stable@vger.kernel.org> # v4.19+
Tested-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
drivers/md/md.c | 27 +++++++++++++++++++++++----
drivers/md/md.h | 3 +++
2 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 021e522001c1..d0f688399a56 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -427,6 +427,7 @@ static void submit_flushes(struct work_struct *ws)
struct mddev *mddev = container_of(ws, struct mddev, flush_work);
struct md_rdev *rdev;
+ mddev->start_flush = ktime_get_boottime();
INIT_WORK(&mddev->flush_work, md_submit_flush_data);
atomic_set(&mddev->flush_pending, 1);
rcu_read_lock();
@@ -467,6 +468,7 @@ static void md_submit_flush_data(struct work_struct *ws)
* could wait for this and below md_handle_request could wait for those
* bios because of suspend check
*/
+ mddev->last_flush = mddev->start_flush;
mddev->flush_bio = NULL;
wake_up(&mddev->sb_wait);
@@ -481,15 +483,32 @@ static void md_submit_flush_data(struct work_struct *ws)
void md_flush_request(struct mddev *mddev, struct bio *bio)
{
+ ktime_t start = ktime_get_boottime();
spin_lock_irq(&mddev->lock);
wait_event_lock_irq(mddev->sb_wait,
- !mddev->flush_bio,
+ !mddev->flush_bio ||
+ ktime_after(mddev->last_flush, start),
mddev->lock);
- mddev->flush_bio = bio;
+ if (!ktime_after(mddev->last_flush, start)) {
+ WARN_ON(mddev->flush_bio);
+ mddev->flush_bio = bio;
+ bio = NULL;
+ }
spin_unlock_irq(&mddev->lock);
- INIT_WORK(&mddev->flush_work, submit_flushes);
- queue_work(md_wq, &mddev->flush_work);
+ if (!bio) {
+ INIT_WORK(&mddev->flush_work, submit_flushes);
+ queue_work(md_wq, &mddev->flush_work);
+ } else {
+ /* flush was performed for some other bio while we waited. */
+ if (bio->bi_iter.bi_size == 0)
+ /* an empty barrier - all done */
+ bio_endio(bio);
+ else {
+ bio->bi_opf &= ~REQ_PREFLUSH;
+ mddev->pers->make_request(mddev, bio);
+ }
+ }
}
EXPORT_SYMBOL(md_flush_request);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 2deb84fa93f9..257cb4c9e22b 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -463,6 +463,9 @@ struct mddev {
*/
struct bio *flush_bio;
atomic_t flush_pending;
+ ktime_t start_flush, last_flush; /* last_flush is when the last completed
+ * flush was started.
+ */
struct work_struct flush_work;
struct work_struct event_work; /* used by dm to report failure event */
void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
--
2.17.1
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