diff options
author | NeilBrown <neilb@suse.com> | 2016-06-02 16:19:53 +1000 |
---|---|---|
committer | Shaohua Li <shli@fb.com> | 2016-06-13 11:54:22 -0700 |
commit | d787be4092e27728cb4c012bee9762098ef3c662 (patch) | |
tree | b8de57ed842d3c01f6fdd4f6ee5be6408763a993 /drivers | |
parent | f5b67ae86ee317db20c0e10d54f16a0bbbd3207d (diff) | |
download | op-kernel-dev-d787be4092e27728cb4c012bee9762098ef3c662.zip op-kernel-dev-d787be4092e27728cb4c012bee9762098ef3c662.tar.gz |
md: reduce the number of synchronize_rcu() calls when multiple devices fail.
Every time a device is removed with ->hot_remove_disk() a synchronize_rcu() call is made
which can delay several milliseconds in some case.
If lots of devices fail at once - as could happen with a large RAID10 where one set
of devices are removed all at once - these delays can add up to be very inconcenient.
As failure is not reversible we can check for that first, setting a
separate flag if it is found, and then all synchronize_rcu() once for
all the flagged devices. Then ->hot_remove_disk() function can skip the
synchronize_rcu() step if the flag is set.
fix build error(Shaohua)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/md/md.c | 29 | ||||
-rw-r--r-- | drivers/md/md.h | 5 | ||||
-rw-r--r-- | drivers/md/multipath.c | 14 | ||||
-rw-r--r-- | drivers/md/raid1.c | 17 | ||||
-rw-r--r-- | drivers/md/raid10.c | 19 | ||||
-rw-r--r-- | drivers/md/raid5.c | 15 |
6 files changed, 69 insertions, 30 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 0793754..2ed547f 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8180,15 +8180,34 @@ static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *rdev; int spares = 0; int removed = 0; + bool remove_some = false; - rdev_for_each(rdev, mddev) + rdev_for_each(rdev, mddev) { + if ((this == NULL || rdev == this) && + rdev->raid_disk >= 0 && + !test_bit(Blocked, &rdev->flags) && + test_bit(Faulty, &rdev->flags) && + atomic_read(&rdev->nr_pending)==0) { + /* Faulty non-Blocked devices with nr_pending == 0 + * never get nr_pending incremented, + * never get Faulty cleared, and never get Blocked set. + * So we can synchronize_rcu now rather than once per device + */ + remove_some = true; + set_bit(RemoveSynchronized, &rdev->flags); + } + } + + if (remove_some) + synchronize_rcu(); + rdev_for_each(rdev, mddev) { if ((this == NULL || rdev == this) && rdev->raid_disk >= 0 && !test_bit(Blocked, &rdev->flags) && - (test_bit(Faulty, &rdev->flags) || + ((test_bit(RemoveSynchronized, &rdev->flags) || (!test_bit(In_sync, &rdev->flags) && !test_bit(Journal, &rdev->flags))) && - atomic_read(&rdev->nr_pending)==0) { + atomic_read(&rdev->nr_pending)==0)) { if (mddev->pers->hot_remove_disk( mddev, rdev) == 0) { sysfs_unlink_rdev(mddev, rdev); @@ -8196,6 +8215,10 @@ static int remove_and_add_spares(struct mddev *mddev, removed++; } } + if (remove_some && test_bit(RemoveSynchronized, &rdev->flags)) + clear_bit(RemoveSynchronized, &rdev->flags); + } + if (removed && mddev->kobj.sd) sysfs_notify(&mddev->kobj, NULL, "degraded"); diff --git a/drivers/md/md.h b/drivers/md/md.h index 03b19aa..dc65ca6 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -163,6 +163,11 @@ enum flag_bits { * than other devices in the array */ ClusterRemove, + RemoveSynchronized, /* synchronize_rcu() was called after + * this device was known to be faulty, + * so it is safe to remove without + * another synchronize_rcu() call. + */ }; static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors, diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c index 7eb9972..c145a5a 100644 --- a/drivers/md/multipath.c +++ b/drivers/md/multipath.c @@ -298,12 +298,14 @@ static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev) goto abort; } p->rdev = NULL; - synchronize_rcu(); - if (atomic_read(&rdev->nr_pending)) { - /* lost the race, try later */ - err = -EBUSY; - p->rdev = rdev; - goto abort; + if (!test_bit(RemoveSynchronized, &rdev->flags)) { + synchronize_rcu(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + p->rdev = rdev; + goto abort; + } } err = md_integrity_register(mddev); } diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 34f20c0..5027ef4 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1656,13 +1656,16 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev) goto abort; } p->rdev = NULL; - synchronize_rcu(); - if (atomic_read(&rdev->nr_pending)) { - /* lost the race, try later */ - err = -EBUSY; - p->rdev = rdev; - goto abort; - } else if (conf->mirrors[conf->raid_disks + number].rdev) { + if (!test_bit(RemoveSynchronized, &rdev->flags)) { + synchronize_rcu(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + p->rdev = rdev; + goto abort; + } + } + if (conf->mirrors[conf->raid_disks + number].rdev) { /* We just removed a device that is being replaced. * Move down the replacement. We drain all IO before * doing this to avoid confusion. diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 34facda..8ee5d96 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1766,7 +1766,7 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev) err = -EBUSY; goto abort; } - /* Only remove faulty devices if recovery + /* Only remove non-faulty devices if recovery * is not possible. */ if (!test_bit(Faulty, &rdev->flags) && @@ -1778,13 +1778,16 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev) goto abort; } *rdevp = NULL; - synchronize_rcu(); - if (atomic_read(&rdev->nr_pending)) { - /* lost the race, try later */ - err = -EBUSY; - *rdevp = rdev; - goto abort; - } else if (p->replacement) { + if (!test_bit(RemoveSynchronized, &rdev->flags)) { + synchronize_rcu(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + *rdevp = rdev; + goto abort; + } + } + if (p->replacement) { /* We must have just cleared 'rdev' */ p->rdev = p->replacement; clear_bit(Replacement, &p->replacement->flags); diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index f6a191a..413cc7d 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7197,12 +7197,15 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev) goto abort; } *rdevp = NULL; - synchronize_rcu(); - if (atomic_read(&rdev->nr_pending)) { - /* lost the race, try later */ - err = -EBUSY; - *rdevp = rdev; - } else if (p->replacement) { + if (!test_bit(RemoveSynchronized, &rdev->flags)) { + synchronize_rcu(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + *rdevp = rdev; + } + } + if (p->replacement) { /* We must have just cleared 'rdev' */ p->rdev = p->replacement; clear_bit(Replacement, &p->replacement->flags); |