Commit 7513c2a7 authored by Jonathan Brassow's avatar Jonathan Brassow Committed by Alasdair G Kergon
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dm raid1: add is_remote_recovering hook for clusters 



The logging API needs an extra function to make cluster mirroring
possible.  This new function allows us to check whether a mirror
region is being recovered on another machine in the cluster.  This
helps us prevent simultaneous recovery I/O and process I/O to the
same locations on disk.

Cluster-aware log modules will implement this function.  Single
machine log modules will not.  So, there is no performance
penalty for single machine mirrors.

Signed-off-by: default avatarJonathan Brassow <jbrassow@redhat.com>
Acked-by: default avatarHeinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent b2a11465

drivers/md/dm-raid1.c

+23 −2
Original line number Diff line number Diff line
@@ -588,6 +588,9 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes) 
	int state;

	struct bio *bio;

	struct bio_list sync, nosync, recover, *this_list = NULL;

	struct bio_list requeue;

	struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);

	region_t region;



	if (!writes->head)

		return;
@@ -598,10 +601,18 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes) 
	bio_list_init(&sync);

	bio_list_init(&nosync);

	bio_list_init(&recover);

	bio_list_init(&requeue);



	while ((bio = bio_list_pop(writes))) {

		state = dm_rh_get_state(ms->rh,

					dm_rh_bio_to_region(ms->rh, bio), 1);

		region = dm_rh_bio_to_region(ms->rh, bio);



		if (log->type->is_remote_recovering &&

		    log->type->is_remote_recovering(log, region)) {

			bio_list_add(&requeue, bio);

			continue;

		}



		state = dm_rh_get_state(ms->rh, region, 1);

		switch (state) {

		case DM_RH_CLEAN:

		case DM_RH_DIRTY:
@@ -620,6 +631,16 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes) 
		bio_list_add(this_list, bio);

	}



	/*

	 * Add bios that are delayed due to remote recovery

	 * back on to the write queue

	 */

	if (unlikely(requeue.head)) {

		spin_lock_irq(&ms->lock);

		bio_list_merge(&ms->writes, &requeue);

		spin_unlock_irq(&ms->lock);

	}



	/*

	 * Increment the pending counts for any regions that will

	 * be written to (writes to recover regions are going to

include/linux/dm-dirty-log.h

+10 −0
Original line number Diff line number Diff line
@@ -116,6 +116,16 @@ struct dm_dirty_log_type { 
	 */

	int (*status)(struct dm_dirty_log *log, status_type_t status_type,

		      char *result, unsigned maxlen);



	/*

	 * is_remote_recovering is necessary for cluster mirroring. It provides

	 * a way to detect recovery on another node, so we aren't writing

	 * concurrently.  This function is likely to block (when a cluster log

	 * is used).

	 *

	 * Returns: 0, 1

	 */

	int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);

};



int dm_dirty_log_type_register(struct dm_dirty_log_type *type);

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