forked from luck/tmp_suning_uos_patched
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>
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@ -8180,15 +8180,34 @@ static int remove_and_add_spares(struct mddev *mddev,
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struct md_rdev *rdev;
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int spares = 0;
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int removed = 0;
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bool remove_some = false;
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rdev_for_each(rdev, mddev)
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rdev_for_each(rdev, mddev) {
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if ((this == NULL || rdev == this) &&
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rdev->raid_disk >= 0 &&
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!test_bit(Blocked, &rdev->flags) &&
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(test_bit(Faulty, &rdev->flags) ||
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test_bit(Faulty, &rdev->flags) &&
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atomic_read(&rdev->nr_pending)==0) {
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/* Faulty non-Blocked devices with nr_pending == 0
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* never get nr_pending incremented,
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* never get Faulty cleared, and never get Blocked set.
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* So we can synchronize_rcu now rather than once per device
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*/
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remove_some = true;
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set_bit(RemoveSynchronized, &rdev->flags);
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}
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}
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if (remove_some)
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synchronize_rcu();
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rdev_for_each(rdev, mddev) {
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if ((this == NULL || rdev == this) &&
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rdev->raid_disk >= 0 &&
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!test_bit(Blocked, &rdev->flags) &&
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((test_bit(RemoveSynchronized, &rdev->flags) ||
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(!test_bit(In_sync, &rdev->flags) &&
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!test_bit(Journal, &rdev->flags))) &&
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atomic_read(&rdev->nr_pending)==0) {
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atomic_read(&rdev->nr_pending)==0)) {
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if (mddev->pers->hot_remove_disk(
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mddev, rdev) == 0) {
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sysfs_unlink_rdev(mddev, rdev);
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@ -8196,6 +8215,10 @@ static int remove_and_add_spares(struct mddev *mddev,
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removed++;
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}
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}
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if (remove_some && test_bit(RemoveSynchronized, &rdev->flags))
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clear_bit(RemoveSynchronized, &rdev->flags);
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}
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if (removed && mddev->kobj.sd)
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sysfs_notify(&mddev->kobj, NULL, "degraded");
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@ -163,6 +163,11 @@ enum flag_bits {
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* than other devices in the array
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*/
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ClusterRemove,
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RemoveSynchronized, /* synchronize_rcu() was called after
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* this device was known to be faulty,
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* so it is safe to remove without
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* another synchronize_rcu() call.
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*/
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};
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static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
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@ -298,12 +298,14 @@ static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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goto abort;
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}
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p->rdev = NULL;
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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p->rdev = rdev;
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goto abort;
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if (!test_bit(RemoveSynchronized, &rdev->flags)) {
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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p->rdev = rdev;
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goto abort;
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}
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}
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err = md_integrity_register(mddev);
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}
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@ -1656,13 +1656,16 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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goto abort;
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}
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p->rdev = NULL;
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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p->rdev = rdev;
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goto abort;
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} else if (conf->mirrors[conf->raid_disks + number].rdev) {
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if (!test_bit(RemoveSynchronized, &rdev->flags)) {
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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p->rdev = rdev;
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goto abort;
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}
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}
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if (conf->mirrors[conf->raid_disks + number].rdev) {
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/* We just removed a device that is being replaced.
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* Move down the replacement. We drain all IO before
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* doing this to avoid confusion.
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@ -1766,7 +1766,7 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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err = -EBUSY;
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goto abort;
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}
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/* Only remove faulty devices if recovery
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/* Only remove non-faulty devices if recovery
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* is not possible.
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*/
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if (!test_bit(Faulty, &rdev->flags) &&
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@ -1778,13 +1778,16 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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goto abort;
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}
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*rdevp = NULL;
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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*rdevp = rdev;
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goto abort;
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} else if (p->replacement) {
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if (!test_bit(RemoveSynchronized, &rdev->flags)) {
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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*rdevp = rdev;
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goto abort;
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}
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}
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if (p->replacement) {
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/* We must have just cleared 'rdev' */
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p->rdev = p->replacement;
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clear_bit(Replacement, &p->replacement->flags);
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@ -7197,12 +7197,15 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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goto abort;
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}
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*rdevp = NULL;
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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*rdevp = rdev;
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} else if (p->replacement) {
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if (!test_bit(RemoveSynchronized, &rdev->flags)) {
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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*rdevp = rdev;
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}
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}
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if (p->replacement) {
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/* We must have just cleared 'rdev' */
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p->rdev = p->replacement;
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clear_bit(Replacement, &p->replacement->flags);
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