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| 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/md/raid1.c | |
| parent | f5b67ae86ee317db20c0e10d54f16a0bbbd3207d (diff) | |
| download | linux-d787be4092e27728cb4c012bee9762098ef3c662.tar.gz linux-d787be4092e27728cb4c012bee9762098ef3c662.tar.bz2 linux-d787be4092e27728cb4c012bee9762098ef3c662.zip | |
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/md/raid1.c')
| -rw-r--r-- | drivers/md/raid1.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 34f20c03d1f6..5027ef4752ac 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. |