[PATCH] device-mapper raid1: add default mirror

This patch introduces a new field to the mirror_set (default_mirror) to store
the default mirror.

(A subsequent patch will allow us to change the default mirror in the event of
a failure.)

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 6b0fc16..6cfa8d4 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -562,6 +562,8 @@ struct mirror_set {
        region_t nr_regions;
        int in_sync;
 
+       struct mirror *default_mirror;  /* Default mirror */
+
        unsigned int nr_mirrors;
        struct mirror mirror[0];
 };
@@ -611,7 +613,7 @@ static int recover(struct mirror_set *ms, struct region *reg)
        unsigned long flags = 0;
 
        /* fill in the source */
-       m = ms->mirror + DEFAULT_MIRROR;
+       m = ms->default_mirror;
        from.bdev = m->dev->bdev;
        from.sector = m->offset + region_to_sector(reg->rh, reg->key);
        if (reg->key == (ms->nr_regions - 1)) {
@@ -627,7 +629,7 @@ static int recover(struct mirror_set *ms, struct region *reg)
 
        /* fill in the destinations */
        for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
-               if (i == DEFAULT_MIRROR)
+               if (&ms->mirror[i] == ms->default_mirror)
                        continue;
 
                m = ms->mirror + i;
@@ -682,7 +684,7 @@ static void do_recovery(struct mirror_set *ms)
 static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
 {
        /* FIXME: add read balancing */
-       return ms->mirror + DEFAULT_MIRROR;
+       return ms->default_mirror;
 }
 
 /*
@@ -709,7 +711,7 @@ static void do_reads(struct mirror_set *ms, struct bio_list *reads)
                if (rh_in_sync(&ms->rh, region, 0))
                        m = choose_mirror(ms, bio->bi_sector);
                else
-                       m = ms->mirror + DEFAULT_MIRROR;
+                       m = ms->default_mirror;
 
                map_bio(ms, m, bio);
                generic_make_request(bio);
@@ -833,7 +835,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
                rh_delay(&ms->rh, bio);
 
        while ((bio = bio_list_pop(&nosync))) {
-               map_bio(ms, ms->mirror + DEFAULT_MIRROR, bio);
+               map_bio(ms, ms->default_mirror, bio);
                generic_make_request(bio);
        }
 }
@@ -900,6 +902,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
        ms->nr_mirrors = nr_mirrors;
        ms->nr_regions = dm_sector_div_up(ti->len, region_size);
        ms->in_sync = 0;
+       ms->default_mirror = &ms->mirror[DEFAULT_MIRROR];
 
        if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
                ti->error = "dm-mirror: Error creating dirty region hash";