md/raid5: prepare for allowing reshape to change layout

Add prev_algo to raid5_conf_t along the same lines as prev_chunk
and previous_raid_disks.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 20 insertions, 14 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7638cc31e7e8..80ec9a6d8a18 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1273,6 +1273,8 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
         int pd_idx, qd_idx;
         int ddf_layout = 0;
         sector_t new_sector;
+        int algorithm = previous ? conf->prev_algo
+                                 : conf->algorithm;
         int sectors_per_chunk = previous ? (conf->prev_chunk >> 9)
                                          : (conf->chunk_size >> 9);
         int raid_disks = previous ? conf->previous_raid_disks
@@ -1307,7 +1309,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                 pd_idx = data_disks;
                 break;
         case 5:
-                switch (conf->algorithm) {
+                switch (algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
                         pd_idx = data_disks - stripe % raid_disks;
                         if (*dd_idx >= pd_idx)
@@ -1335,13 +1337,13 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                         break;
                 default:
                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
-                                conf->algorithm);
+                                algorithm);
                         BUG();
                 }
                 break;
         case 6:
 
-                switch (conf->algorithm) {
+                switch (algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
                         pd_idx = raid_disks - 1 - (stripe % raid_disks);
                         qd_idx = pd_idx + 1;
@@ -1454,7 +1456,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
 
                 default:
                         printk(KERN_CRIT "raid6: unsupported algorithm %d\n",
-                               conf->algorithm);
+                               algorithm);
                         BUG();
                 }
                 break;
@@ -1481,6 +1483,8 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
         sector_t new_sector = sh->sector, check;
         int sectors_per_chunk = previous ? (conf->prev_chunk >> 9)
                                          : (conf->chunk_size >> 9);
+        int algorithm = previous ? conf->prev_algo
+                                 : conf->algorithm;
         sector_t stripe;
         int chunk_offset;
         int chunk_number, dummy1, dd_idx = i;
@@ -1497,7 +1501,7 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
         switch(conf->level) {
         case 4: break;
         case 5:
-                switch (conf->algorithm) {
+                switch (algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
                 case ALGORITHM_RIGHT_ASYMMETRIC:
                         if (i > sh->pd_idx)
@@ -1516,14 +1520,14 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                         break;
                 default:
                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
-                               conf->algorithm);
+                               algorithm);
                         BUG();
                 }
                 break;
         case 6:
                 if (i == sh->qd_idx)
                         return 0; /* It is the Q disk */
-                switch (conf->algorithm) {
+                switch (algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
                 case ALGORITHM_RIGHT_ASYMMETRIC:
                 case ALGORITHM_ROTATING_ZERO_RESTART:
@@ -1571,7 +1575,7 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                         break;
                 default:
                         printk(KERN_CRIT "raid6: unsupported algorithm %d\n",
-                               conf->algorithm);
+                               algorithm);
                         BUG();
                 }
                 break;
@@ -4330,8 +4334,10 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
         conf->algorithm = mddev->new_layout;
         conf->max_nr_stripes = NR_STRIPES;
         conf->reshape_progress = mddev->reshape_position;
-        if (conf->reshape_progress != MaxSector)
+        if (conf->reshape_progress != MaxSector) {
                 conf->prev_chunk = mddev->chunk_size;
+                conf->prev_algo = mddev->layout;
+        }
 
         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
                  conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
@@ -4472,14 +4478,14 @@ static int run(mddev_t *mddev)
 
         if (mddev->degraded == 0)
                 printk("raid5: raid level %d set %s active with %d out of %d"
-                        " devices, algorithm %d\n", conf->level, mdname(mddev), 
-                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
-                        conf->algorithm);
+                       " devices, algorithm %d\n", conf->level, mdname(mddev),
+                       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
+                       mddev->new_layout);
         else
                 printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
                         " out of %d devices, algorithm %d\n", conf->level,
                         mdname(mddev), mddev->raid_disks - mddev->degraded,
-                        mddev->raid_disks, conf->algorithm);
+                        mddev->raid_disks, mddev->new_layout);
 
         print_raid5_conf(conf);
 
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index b9c93280fc1d..cdd045681720 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -350,7 +350,7 @@ struct raid5_private_data {
          */
         sector_t                reshape_safe;
         int                     previous_raid_disks;
-        int                     prev_chunk;
+        int                     prev_chunk, prev_algo;
         short                   generation; /* increments with every reshape */
 
         struct list_head        handle_list; /* stripes needing handling */