2 files changed, 64 insertions, 30 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 6c20b44509d8..7a6df515b008 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -178,10 +178,10 @@ static int grow_buffers(struct stripe_head *sh, int num)
 
 static void raid5_build_block (struct stripe_head *sh, int i);
 
-static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
+static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
 {
         raid5_conf_t *conf = sh->raid_conf;
-        int disks = conf->raid_disks, i;
+        int i;
 
         if (atomic_read(&sh->count) != 0)
                 BUG();
@@ -198,7 +198,9 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
         sh->pd_idx = pd_idx;
         sh->state = 0;
 
-        for (i=disks; i--; ) {
+        sh->disks = disks;
+
+        for (i = sh->disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
 
                 if (dev->toread || dev->towrite || dev->written ||
@@ -215,7 +217,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
         insert_hash(conf, sh);
 }
 
-static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
+static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, int disks)
 {
         struct stripe_head *sh;
         struct hlist_node *hn;
@@ -223,7 +225,7 @@ static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
         CHECK_DEVLOCK();
         PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
-                if (sh->sector == sector)
+                if (sh->sector == sector && sh->disks == disks)
                         return sh;
         PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
         return NULL;
@@ -232,8 +234,8 @@ static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector)
 static void unplug_slaves(mddev_t *mddev);
 static void raid5_unplug_device(request_queue_t *q);
 
-static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector,
-                                             int pd_idx, int noblock) 
+static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
+                                             int pd_idx, int noblock)
 {
         struct stripe_head *sh;
 
@@ -245,7 +247,7 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
                 wait_event_lock_irq(conf->wait_for_stripe,
                                     conf->quiesce == 0,
                                     conf->device_lock, /* nothing */);
-                sh = __find_stripe(conf, sector);
+                sh = __find_stripe(conf, sector, disks);
                 if (!sh) {
                         if (!conf->inactive_blocked)
                                 sh = get_free_stripe(conf);
@@ -263,7 +265,7 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
                                         );
                                 conf->inactive_blocked = 0;
                         } else
-                                init_stripe(sh, sector, pd_idx);
+                                init_stripe(sh, sector, pd_idx, disks);
                 } else {
                         if (atomic_read(&sh->count)) {
                                 if (!list_empty(&sh->lru))
@@ -300,6 +302,7 @@ static int grow_one_stripe(raid5_conf_t *conf)
                 kmem_cache_free(conf->slab_cache, sh);
                 return 0;
         }
+        sh->disks = conf->raid_disks;
         /* we just created an active stripe so... */
         atomic_set(&sh->count, 1);
         atomic_inc(&conf->active_stripes);
@@ -483,7 +486,7 @@ static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
 {
         struct stripe_head *sh = bi->bi_private;
         raid5_conf_t *conf = sh->raid_conf;
-        int disks = conf->raid_disks, i;
+        int disks = sh->disks, i;
         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 
         if (bi->bi_size)
@@ -581,7 +584,7 @@ static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done,
 {
         struct stripe_head *sh = bi->bi_private;
         raid5_conf_t *conf = sh->raid_conf;
-        int disks = conf->raid_disks, i;
+        int disks = sh->disks, i;
         unsigned long flags;
         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
 
@@ -735,7 +738,7 @@ static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
 static sector_t compute_blocknr(struct stripe_head *sh, int i)
 {
         raid5_conf_t *conf = sh->raid_conf;
-        int raid_disks = conf->raid_disks, data_disks = raid_disks - 1;
+        int raid_disks = sh->disks, data_disks = raid_disks - 1;
         sector_t new_sector = sh->sector, check;
         int sectors_per_chunk = conf->chunk_size >> 9;
         sector_t stripe;
@@ -836,8 +839,7 @@ static void copy_data(int frombio, struct bio *bio,
 
 static void compute_block(struct stripe_head *sh, int dd_idx)
 {
-        raid5_conf_t *conf = sh->raid_conf;
-        int i, count, disks = conf->raid_disks;
+        int i, count, disks = sh->disks;
         void *ptr[MAX_XOR_BLOCKS], *p;
 
         PRINTK("compute_block, stripe %llu, idx %d\n", 
@@ -867,7 +869,7 @@ static void compute_block(struct stripe_head *sh, int dd_idx)
 static void compute_parity(struct stripe_head *sh, int method)
 {
         raid5_conf_t *conf = sh->raid_conf;
-        int i, pd_idx = sh->pd_idx, disks = conf->raid_disks, count;
+        int i, pd_idx = sh->pd_idx, disks = sh->disks, count;
         void *ptr[MAX_XOR_BLOCKS];
         struct bio *chosen;
 
@@ -1055,7 +1057,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 static void handle_stripe(struct stripe_head *sh)
 {
         raid5_conf_t *conf = sh->raid_conf;
-        int disks = conf->raid_disks;
+        int disks = sh->disks;
         struct bio *return_bi= NULL;
         struct bio *bi;
         int i;
@@ -1649,12 +1651,10 @@ static inline void raid5_plug_device(raid5_conf_t *conf)
         spin_unlock_irq(&conf->device_lock);
 }
 
-static int make_request (request_queue_t *q, struct bio * bi)
+static int make_request(request_queue_t *q, struct bio * bi)
 {
         mddev_t *mddev = q->queuedata;
         raid5_conf_t *conf = mddev_to_conf(mddev);
-        const unsigned int raid_disks = conf->raid_disks;
-        const unsigned int data_disks = raid_disks - 1;
         unsigned int dd_idx, pd_idx;
         sector_t new_sector;
         sector_t logical_sector, last_sector;
@@ -1678,20 +1678,48 @@ static int make_request (request_queue_t *q, struct bio * bi)
 
         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
                 DEFINE_WAIT(w);
+                int disks;
                 
-                new_sector = raid5_compute_sector(logical_sector,
-                                                  raid_disks, data_disks, &dd_idx, &pd_idx, conf);
-
+        retry:
+                if (likely(conf->expand_progress == MaxSector))
+                        disks = conf->raid_disks;
+                else {
+                        spin_lock_irq(&conf->device_lock);
+                        disks = conf->raid_disks;
+                        if (logical_sector >= conf->expand_progress)
+                                disks = conf->previous_raid_disks;
+                        spin_unlock_irq(&conf->device_lock);
+                }
+                new_sector = raid5_compute_sector(logical_sector, disks, disks - 1,
+                                                  &dd_idx, &pd_idx, conf);
                 PRINTK("raid5: make_request, sector %llu logical %llu\n",
                         (unsigned long long)new_sector, 
                         (unsigned long long)logical_sector);
 
-        retry:
                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
-                sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
+                sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
                 if (sh) {
-                        if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
-                                /* Add failed due to overlap.  Flush everything
+                        if (unlikely(conf->expand_progress != MaxSector)) {
+                                /* expansion might have moved on while waiting for a
+                                 * stripe, so we much do the range check again.
+                                 */
+                                int must_retry = 0;
+                                spin_lock_irq(&conf->device_lock);
+                                if (logical_sector <  conf->expand_progress &&
+                                    disks == conf->previous_raid_disks)
+                                        /* mismatch, need to try again */
+                                        must_retry = 1;
+                                spin_unlock_irq(&conf->device_lock);
+                                if (must_retry) {
+                                        release_stripe(sh);
+                                        goto retry;
+                                }
+                        }
+
+                        if (test_bit(STRIPE_EXPANDING, &sh->state) ||
+                            !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
+                                /* Stripe is busy expanding or
+                                 * add failed due to overlap.  Flush everything
                                  * and wait a while
                                  */
                                 raid5_unplug_device(mddev->queue);
@@ -1703,7 +1731,6 @@ static int make_request (request_queue_t *q, struct bio * bi)
                         raid5_plug_device(conf);
                         handle_stripe(sh);
                         release_stripe(sh);
-
                 } else {
                         /* cannot get stripe for read-ahead, just give-up */
                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
@@ -1779,9 +1806,9 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
 
         first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk
                 + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf);
-        sh = get_active_stripe(conf, sector_nr, pd_idx, 1);
+        sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
         if (sh == NULL) {
-                sh = get_active_stripe(conf, sector_nr, pd_idx, 0);
+                sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
                 /* make sure we don't swamp the stripe cache if someone else
                  * is trying to get access 
                  */
@@ -1998,6 +2025,7 @@ static int run(mddev_t *mddev)
         conf->level = mddev->level;
         conf->algorithm = mddev->layout;
         conf->max_nr_stripes = NR_STRIPES;
+        conf->expand_progress = MaxSector;
 
         /* device size must be a multiple of chunk size */
         mddev->size &= ~(mddev->chunk_size/1024 -1);
@@ -2128,7 +2156,7 @@ static void print_sh (struct stripe_head *sh)
         printk("sh %llu,  count %d.\n",
                 (unsigned long long)sh->sector, atomic_read(&sh->count));
         printk("sh %llu, ", (unsigned long long)sh->sector);
-        for (i = 0; i < sh->raid_conf->raid_disks; i++) {
+        for (i = 0; i < sh->disks; i++) {
                 printk("(cache%d: %p %ld) ", 
                         i, sh->dev[i].page, sh->dev[i].flags);
         }
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index b7b2653af7bb..6fa274aea2a0 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -135,6 +135,7 @@ struct stripe_head {
         atomic_t                count;                  /* nr of active thread/requests */
         spinlock_t              lock;
         int                     bm_seq; /* sequence number for bitmap flushes */
+        int                     disks;                  /* disks in stripe */
         struct r5dev {
                 struct bio      req;
                 struct bio_vec  vec;
@@ -174,6 +175,7 @@ struct stripe_head {
 #define STRIPE_DELAYED          6
 #define STRIPE_DEGRADED         7
 #define STRIPE_BIT_DELAY        8
+#define STRIPE_EXPANDING        9
 
 /*
  * Plugging:
@@ -211,6 +213,10 @@ struct raid5_private_data {
         int                     raid_disks, working_disks, failed_disks;
         int                     max_nr_stripes;
 
+        /* used during an expand */
+        sector_t                expand_progress;        /* MaxSector when no expand happening */
+        int                     previous_raid_disks;
+
         struct list_head        handle_list; /* stripes needing handling */
         struct list_head        delayed_list; /* stripes that have plugged requests */
         struct list_head        bitmap_list; /* stripes delaying awaiting bitmap update */