md/raid10: prepare data structures for handling replacement.

Allow each slot in the RAID10 to have 2 devices, the want_replacement
and the replacement.

Also an r10bio to have 2 bios, and for resync/recovery allocate the
second bio if there are any replacement devices.

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

2 files changed, 78 insertions, 31 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index f5088dda4dca..9722065022fa 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -73,7 +73,8 @@ static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
         struct r10conf *conf = data;
         int size = offsetof(struct r10bio, devs[conf->copies]);
 
-        /* allocate a r10bio with room for raid_disks entries in the bios array */
+        /* allocate a r10bio with room for raid_disks entries in the
+         * bios array */
         return kzalloc(size, gfp_flags);
 }
 
@@ -123,12 +124,19 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
                 if (!bio)
                         goto out_free_bio;
                 r10_bio->devs[j].bio = bio;
+                if (!conf->have_replacement)
+                        continue;
+                bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
+                if (!bio)
+                        goto out_free_bio;
+                r10_bio->devs[j].repl_bio = bio;
         }
         /*
          * Allocate RESYNC_PAGES data pages and attach them
          * where needed.
          */
         for (j = 0 ; j < nalloc; j++) {
+                struct bio *rbio = r10_bio->devs[j].repl_bio;
                 bio = r10_bio->devs[j].bio;
                 for (i = 0; i < RESYNC_PAGES; i++) {
                         if (j == 1 && !test_bit(MD_RECOVERY_SYNC,
@@ -143,6 +151,8 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
                                 goto out_free_pages;
 
                         bio->bi_io_vec[i].bv_page = page;
+                        if (rbio)
+                                rbio->bi_io_vec[i].bv_page = page;
                 }
         }
 
@@ -156,8 +166,11 @@ out_free_pages:
                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
         j = -1;
 out_free_bio:
-        while ( ++j < nalloc )
+        while (++j < nalloc) {
                 bio_put(r10_bio->devs[j].bio);
+                if (r10_bio->devs[j].repl_bio)
+                        bio_put(r10_bio->devs[j].repl_bio);
+        }
         r10bio_pool_free(r10_bio, conf);
         return NULL;
 }
@@ -178,6 +191,9 @@ static void r10buf_pool_free(void *__r10_bio, void *data)
                         }
                         bio_put(bio);
                 }
+                bio = r10bio->devs[j].repl_bio;
+                if (bio)
+                        bio_put(bio);
         }
         r10bio_pool_free(r10bio, conf);
 }
@@ -191,6 +207,10 @@ static void put_all_bios(struct r10conf *conf, struct r10bio *r10_bio)
                 if (!BIO_SPECIAL(*bio))
                         bio_put(*bio);
                 *bio = NULL;
+                bio = &r10_bio->devs[i].repl_bio;
+                if (r10_bio->read_slot < 0 && !BIO_SPECIAL(*bio))
+                        bio_put(*bio);
+                *bio = NULL;
         }
 }
 
@@ -275,19 +295,27 @@ static inline void update_head_pos(int slot, struct r10bio *r10_bio)
  * Find the disk number which triggered given bio
  */
 static int find_bio_disk(struct r10conf *conf, struct r10bio *r10_bio,
-                         struct bio *bio, int *slotp)
+                         struct bio *bio, int *slotp, int *replp)
 {
         int slot;
+        int repl = 0;
 
-        for (slot = 0; slot < conf->copies; slot++)
+        for (slot = 0; slot < conf->copies; slot++) {
                 if (r10_bio->devs[slot].bio == bio)
                         break;
+                if (r10_bio->devs[slot].repl_bio == bio) {
+                        repl = 1;
+                        break;
+                }
+        }
 
         BUG_ON(slot == conf->copies);
         update_head_pos(slot, r10_bio);
 
         if (slotp)
                 *slotp = slot;
+        if (replp)
+                *replp = repl;
         return r10_bio->devs[slot].devnum;
 }
 
@@ -368,7 +396,7 @@ static void raid10_end_write_request(struct bio *bio, int error)
         struct r10conf *conf = r10_bio->mddev->private;
         int slot;
 
-        dev = find_bio_disk(conf, r10_bio, bio, &slot);
+        dev = find_bio_disk(conf, r10_bio, bio, &slot, NULL);
 
         /*
          * this branch is our 'one mirror IO has finished' event handler:
@@ -1025,6 +1053,7 @@ read_again:
          */
         plugged = mddev_check_plugged(mddev);
 
+        r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
         raid10_find_phys(conf, r10_bio);
 retry_write:
         blocked_rdev = NULL;
@@ -1431,7 +1460,7 @@ static void end_sync_read(struct bio *bio, int error)
         struct r10conf *conf = r10_bio->mddev->private;
         int d;
 
-        d = find_bio_disk(conf, r10_bio, bio, NULL);
+        d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
 
         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
                 set_bit(R10BIO_Uptodate, &r10_bio->state);
@@ -1493,7 +1522,7 @@ static void end_sync_write(struct bio *bio, int error)
         int bad_sectors;
         int slot;
 
-        d = find_bio_disk(conf, r10_bio, bio, &slot);
+        d = find_bio_disk(conf, r10_bio, bio, &slot, NULL);
 
         if (!uptodate) {
                 set_bit(WriteErrorSeen, &conf->mirrors[d].rdev->flags);
@@ -2271,9 +2300,14 @@ static void raid10d(struct mddev *mddev)
 static int init_resync(struct r10conf *conf)
 {
         int buffs;
+        int i;
 
         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
         BUG_ON(conf->r10buf_pool);
+        conf->have_replacement = 0;
+        for (i = 0; i < conf->raid_disks; i++)
+                if (conf->mirrors[i].replacement)
+                        conf->have_replacement = 1;
         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
         if (!conf->r10buf_pool)
                 return -ENOMEM;
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
index 7facfdf841f4..7c615613c381 100644
--- a/drivers/md/raid10.h
+++ b/drivers/md/raid10.h
@@ -2,7 +2,7 @@
 #define _RAID10_H
 
 struct mirror_info {
-        struct md_rdev  *rdev;
+        struct md_rdev  *rdev, *replacement;
         sector_t        head_position;
         int             recovery_disabled;      /* matches
                                                  * mddev->recovery_disabled
@@ -18,12 +18,13 @@ struct r10conf {
         spinlock_t              device_lock;