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>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index f5088dd..9722065 100644 (file)
--- 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 7facfdf..7c61561 100644 (file)
--- 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;
 
        /* geometry */
-       int                     near_copies;  /* number of copies laid out raid0 style */
+       int                     near_copies;  /* number of copies laid out
+                                              * raid0 style */
        int                     far_copies;   /* number of copies laid out
                                               * at large strides across drives
                                               */
-       int                     far_offset;   /* far_copies are offset by 1 stripe
-                                              * instead of many
+       int                     far_offset;   /* far_copies are offset by 1
+                                              * stripe instead of many
                                               */
        int                     copies;       /* near_copies * far_copies.
                                               * must be <= raid_disks
@@ -34,10 +35,11 @@ struct r10conf {
                                               * 1 stripe.
                                               */
 
-       sector_t                dev_sectors;  /* temp copy of mddev->dev_sectors */
+       sector_t                dev_sectors;  /* temp copy of
+                                              * mddev->dev_sectors */
 
-       int chunk_shift; /* shift from chunks to sectors */
-       sector_t chunk_mask;
+       int                     chunk_shift; /* shift from chunks to sectors */
+       sector_t                chunk_mask;
 
        struct list_head        retry_list;
        /* queue pending writes and submit them on unplug */
@@ -45,20 +47,22 @@ struct r10conf {
        int                     pending_count;
 
        spinlock_t              resync_lock;
-       int nr_pending;
-       int nr_waiting;
-       int nr_queued;
-       int barrier;
+       int                     nr_pending;
+       int                     nr_waiting;
+       int                     nr_queued;
+       int                     barrier;
        sector_t                next_resync;
        int                     fullsync;  /* set to 1 if a full sync is needed,
                                            * (fresh device added).
                                            * Cleared when a sync completes.
                                            */
-
+       int                     have_replacement; /* There is at least one
+                                                  * replacement device.
+                                                  */
        wait_queue_head_t       wait_barrier;
 
-       mempool_t *r10bio_pool;
-       mempool_t *r10buf_pool;
+       mempool_t               *r10bio_pool;
+       mempool_t               *r10buf_pool;
        struct page             *tmppage;
 
        /* When taking over an array from a different personality, we store
@@ -98,11 +102,18 @@ struct r10bio {
         * When resyncing we also use one for each copy.
         * When reconstructing, we use 2 bios, one for read, one for write.
         * We choose the number when they are allocated.
+        * We sometimes need an extra bio to write to the replacement.
         */
        struct {
-               struct bio              *bio;
-               sector_t addr;
-               int devnum;
+               struct bio      *bio;
+               union {
+                       struct bio      *repl_bio; /* used for resync and
+                                                   * writes */
+                       struct md_rdev  *rdev;     /* used for reads
+                                                   * (read_slot >= 0) */
+               };
+               sector_t        addr;
+               int             devnum;
        } devs[0];
 };
 
@@ -121,17 +132,19 @@ struct r10bio {
 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
 
 /* bits for r10bio.state */
-#define        R10BIO_Uptodate 0
-#define        R10BIO_IsSync   1
-#define        R10BIO_IsRecover 2
-#define        R10BIO_Degraded 3
+enum r10bio_state {
+       R10BIO_Uptodate,
+       R10BIO_IsSync,
+       R10BIO_IsRecover,
+       R10BIO_Degraded,
 /* Set ReadError on bios that experience a read error
  * so that raid10d knows what to do with them.
  */
-#define        R10BIO_ReadError 4
+       R10BIO_ReadError,
 /* If a write for this request means we can clear some
  * known-bad-block records, we set this flag.
  */
-#define        R10BIO_MadeGood 5
-#define        R10BIO_WriteError 6
+       R10BIO_MadeGood,
+       R10BIO_WriteError,
+};
 #endif