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: Jonathan Brassow <jbrassow@redhat.com>
Acked-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 62d594889ac3..536ef0bef154 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -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:
@@ -621,6 +632,16 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
         }
 
         /*
+         * 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
          * be delayed).