Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff
[linux-2.6.git] / drivers / md / raid5.c
index 3cb11ac..3184360 100644 (file)
 #include <linux/raid/raid5.h>
 #include <linux/highmem.h>
 #include <linux/bitops.h>
+#include <linux/kthread.h>
 #include <asm/atomic.h>
 
+#include <linux/raid/bitmap.h>
+
 /*
  * Stripe cache
  */
 #define STRIPE_SHIFT           (PAGE_SHIFT - 9)
 #define STRIPE_SECTORS         (STRIPE_SIZE>>9)
 #define        IO_THRESHOLD            1
-#define HASH_PAGES             1
-#define HASH_PAGES_ORDER       0
-#define NR_HASH                        (HASH_PAGES * PAGE_SIZE / sizeof(struct stripe_head *))
+#define NR_HASH                        (PAGE_SIZE / sizeof(struct hlist_head))
 #define HASH_MASK              (NR_HASH - 1)
 
-#define stripe_hash(conf, sect)        ((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK])
+#define stripe_hash(conf, sect)        (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
 
 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
  * order without overlap.  There may be several bio's per stripe+device, and
 
 static void print_raid5_conf (raid5_conf_t *conf);
 
-static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
+static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
 {
        if (atomic_dec_and_test(&sh->count)) {
-               if (!list_empty(&sh->lru))
-                       BUG();
-               if (atomic_read(&conf->active_stripes)==0)
-                       BUG();
+               BUG_ON(!list_empty(&sh->lru));
+               BUG_ON(atomic_read(&conf->active_stripes)==0);
                if (test_bit(STRIPE_HANDLE, &sh->state)) {
                        if (test_bit(STRIPE_DELAYED, &sh->state))
                                list_add_tail(&sh->lru, &conf->delayed_list);
-                       else
+                       else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
+                                conf->seq_write == sh->bm_seq)
+                               list_add_tail(&sh->lru, &conf->bitmap_list);
+                       else {
+                               clear_bit(STRIPE_BIT_DELAY, &sh->state);
                                list_add_tail(&sh->lru, &conf->handle_list);
+                       }
                        md_wakeup_thread(conf->mddev->thread);
                } else {
                        if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
@@ -88,11 +92,11 @@ static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
                                if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
                                        md_wakeup_thread(conf->mddev->thread);
                        }
-                       list_add_tail(&sh->lru, &conf->inactive_list);
                        atomic_dec(&conf->active_stripes);
-                       if (!conf->inactive_blocked ||
-                           atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
+                       if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
+                               list_add_tail(&sh->lru, &conf->inactive_list);
                                wake_up(&conf->wait_for_stripe);
+                       }
                }
        }
 }
@@ -106,29 +110,21 @@ static void release_stripe(struct stripe_head *sh)
        spin_unlock_irqrestore(&conf->device_lock, flags);
 }
 
-static void remove_hash(struct stripe_head *sh)
+static inline void remove_hash(struct stripe_head *sh)
 {
        PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 
-       if (sh->hash_pprev) {
-               if (sh->hash_next)
-                       sh->hash_next->hash_pprev = sh->hash_pprev;
-               *sh->hash_pprev = sh->hash_next;
-               sh->hash_pprev = NULL;
-       }
+       hlist_del_init(&sh->hash);
 }
 
-static __inline__ void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
+static void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
 {
-       struct stripe_head **shp = &stripe_hash(conf, sh->sector);
+       struct hlist_head *hp = stripe_hash(conf, sh->sector);
 
        PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector);
 
        CHECK_DEVLOCK();
-       if ((sh->hash_next = *shp) != NULL)
-               (*shp)->hash_pprev = &sh->hash_next;
-       *shp = sh;
-       sh->hash_pprev = shp;
+       hlist_add_head(&sh->hash, hp);
 }
 
 
@@ -160,7 +156,7 @@ static void shrink_buffers(struct stripe_head *sh, int num)
                if (!p)
                        continue;
                sh->dev[i].page = NULL;
-               page_cache_release(p);
+               put_page(p);
        }
 }
 
@@ -181,15 +177,13 @@ static int grow_buffers(struct stripe_head *sh, int num)
 
 static void raid5_build_block (struct stripe_head *sh, int i);
 
-static inline 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();
-       if (test_bit(STRIPE_HANDLE, &sh->state))
-               BUG();
+       BUG_ON(atomic_read(&sh->count) != 0);
+       BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
        
        CHECK_DEVLOCK();
        PRINTK("init_stripe called, stripe %llu\n", 
@@ -201,7 +195,9 @@ static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_i
        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 ||
@@ -218,14 +214,15 @@ static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_i
        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;
 
        CHECK_DEVLOCK();
        PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector);
-       for (sh = stripe_hash(conf, sector); sh; sh = sh->hash_next)
-               if (sh->sector == sector)
+       hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
+               if (sh->sector == sector && sh->disks == disks)
                        return sh;
        PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector);
        return NULL;
@@ -234,8 +231,8 @@ 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;
 
@@ -244,7 +241,10 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
        spin_lock_irq(&conf->device_lock);
 
        do {
-               sh = __find_stripe(conf, sector);
+               wait_event_lock_irq(conf->wait_for_stripe,
+                                   conf->quiesce == 0,
+                                   conf->device_lock, /* nothing */);
+               sh = __find_stripe(conf, sector, disks);
                if (!sh) {
                        if (!conf->inactive_blocked)
                                sh = get_free_stripe(conf);
@@ -254,24 +254,23 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
                                conf->inactive_blocked = 1;
                                wait_event_lock_irq(conf->wait_for_stripe,
                                                    !list_empty(&conf->inactive_list) &&
-                                                   (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
+                                                   (atomic_read(&conf->active_stripes)
+                                                    < (conf->max_nr_stripes *3/4)
                                                     || !conf->inactive_blocked),
                                                    conf->device_lock,
-                                                   unplug_slaves(conf->mddev);
+                                                   unplug_slaves(conf->mddev)
                                        );
                                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))
-                                       BUG();
+                         BUG_ON(!list_empty(&sh->lru));
                        } else {
                                if (!test_bit(STRIPE_HANDLE, &sh->state))
                                        atomic_inc(&conf->active_stripes);
-                               if (list_empty(&sh->lru))
-                                       BUG();
-                               list_del_init(&sh->lru);
+                               if (!list_empty(&sh->lru))
+                                       list_del_init(&sh->lru);
                        }
                }
        } while (sh == NULL);
@@ -283,68 +282,207 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
        return sh;
 }
 
-static int grow_stripes(raid5_conf_t *conf, int num)
+static int grow_one_stripe(raid5_conf_t *conf)
 {
        struct stripe_head *sh;
+       sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
+       if (!sh)
+               return 0;
+       memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
+       sh->raid_conf = conf;
+       spin_lock_init(&sh->lock);
+
+       if (grow_buffers(sh, conf->raid_disks)) {
+               shrink_buffers(sh, conf->raid_disks);
+               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);
+       INIT_LIST_HEAD(&sh->lru);
+       release_stripe(sh);
+       return 1;
+}
+
+static int grow_stripes(raid5_conf_t *conf, int num)
+{
        kmem_cache_t *sc;
        int devs = conf->raid_disks;
 
-       sprintf(conf->cache_name, "raid5/%s", mdname(conf->mddev));
-
-       sc = kmem_cache_create(conf->cache_name, 
+       sprintf(conf->cache_name[0], "raid5/%s", mdname(conf->mddev));
+       sprintf(conf->cache_name[1], "raid5/%s-alt", mdname(conf->mddev));
+       conf->active_name = 0;
+       sc = kmem_cache_create(conf->cache_name[conf->active_name],
                               sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
                               0, 0, NULL, NULL);
        if (!sc)
                return 1;
        conf->slab_cache = sc;
+       conf->pool_size = devs;
        while (num--) {
-               sh = kmem_cache_alloc(sc, GFP_KERNEL);
-               if (!sh)
-                       return 1;
-               memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev));
-               sh->raid_conf = conf;
-               spin_lock_init(&sh->lock);
-
-               if (grow_buffers(sh, conf->raid_disks)) {
-                       shrink_buffers(sh, conf->raid_disks);
-                       kmem_cache_free(sc, sh);
+               if (!grow_one_stripe(conf))
                        return 1;
-               }
-               /* we just created an active stripe so... */
-               atomic_set(&sh->count, 1);
-               atomic_inc(&conf->active_stripes);
-               INIT_LIST_HEAD(&sh->lru);
-               release_stripe(sh);
        }
        return 0;
 }
 
-static void shrink_stripes(raid5_conf_t *conf)
+#ifdef CONFIG_MD_RAID5_RESHAPE
+static int resize_stripes(raid5_conf_t *conf, int newsize)
 {
-       struct stripe_head *sh;
+       /* Make all the stripes able to hold 'newsize' devices.
+        * New slots in each stripe get 'page' set to a new page.
+        *
+        * This happens in stages:
+        * 1/ create a new kmem_cache and allocate the required number of
+        *    stripe_heads.
+        * 2/ gather all the old stripe_heads and tranfer the pages across
+        *    to the new stripe_heads.  This will have the side effect of
+        *    freezing the array as once all stripe_heads have been collected,
+        *    no IO will be possible.  Old stripe heads are freed once their
+        *    pages have been transferred over, and the old kmem_cache is
+        *    freed when all stripes are done.
+        * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
+        *    we simple return a failre status - no need to clean anything up.
+        * 4/ allocate new pages for the new slots in the new stripe_heads.
+        *    If this fails, we don't bother trying the shrink the
+        *    stripe_heads down again, we just leave them as they are.
+        *    As each stripe_head is processed the new one is released into
+        *    active service.
+        *
+        * Once step2 is started, we cannot afford to wait for a write,
+        * so we use GFP_NOIO allocations.
+        */
+       struct stripe_head *osh, *nsh;
+       LIST_HEAD(newstripes);
+       struct disk_info *ndisks;
+       int err = 0;
+       kmem_cache_t *sc;
+       int i;
 
-       while (1) {
+       if (newsize <= conf->pool_size)
+               return 0; /* never bother to shrink */
+
+       /* Step 1 */
+       sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
+                              sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
+                              0, 0, NULL, NULL);
+       if (!sc)
+               return -ENOMEM;
+
+       for (i = conf->max_nr_stripes; i; i--) {
+               nsh = kmem_cache_alloc(sc, GFP_KERNEL);
+               if (!nsh)
+                       break;
+
+               memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
+
+               nsh->raid_conf = conf;
+               spin_lock_init(&nsh->lock);
+
+               list_add(&nsh->lru, &newstripes);
+       }
+       if (i) {
+               /* didn't get enough, give up */
+               while (!list_empty(&newstripes)) {
+                       nsh = list_entry(newstripes.next, struct stripe_head, lru);
+                       list_del(&nsh->lru);
+                       kmem_cache_free(sc, nsh);
+               }
+               kmem_cache_destroy(sc);
+               return -ENOMEM;
+       }
+       /* Step 2 - Must use GFP_NOIO now.
+        * OK, we have enough stripes, start collecting inactive
+        * stripes and copying them over
+        */
+       list_for_each_entry(nsh, &newstripes, lru) {
                spin_lock_irq(&conf->device_lock);
-               sh = get_free_stripe(conf);
+               wait_event_lock_irq(conf->wait_for_stripe,
+                                   !list_empty(&conf->inactive_list),
+                                   conf->device_lock,
+                                   unplug_slaves(conf->mddev)
+                       );
+               osh = get_free_stripe(conf);
                spin_unlock_irq(&conf->device_lock);
-               if (!sh)
-                       break;
-               if (atomic_read(&sh->count))
-                       BUG();
-               shrink_buffers(sh, conf->raid_disks);
-               kmem_cache_free(conf->slab_cache, sh);
-               atomic_dec(&conf->active_stripes);
+               atomic_set(&nsh->count, 1);
+               for(i=0; i<conf->pool_size; i++)
+                       nsh->dev[i].page = osh->dev[i].page;
+               for( ; i<newsize; i++)
+                       nsh->dev[i].page = NULL;
+               kmem_cache_free(conf->slab_cache, osh);
        }
        kmem_cache_destroy(conf->slab_cache);
+
+       /* Step 3.
+        * At this point, we are holding all the stripes so the array
+        * is completely stalled, so now is a good time to resize
+        * conf->disks.
+        */
+       ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
+       if (ndisks) {
+               for (i=0; i<conf->raid_disks; i++)
+                       ndisks[i] = conf->disks[i];
+               kfree(conf->disks);
+               conf->disks = ndisks;
+       } else
+               err = -ENOMEM;
+
+       /* Step 4, return new stripes to service */
+       while(!list_empty(&newstripes)) {
+               nsh = list_entry(newstripes.next, struct stripe_head, lru);
+               list_del_init(&nsh->lru);
+               for (i=conf->raid_disks; i < newsize; i++)
+                       if (nsh->dev[i].page == NULL) {
+                               struct page *p = alloc_page(GFP_NOIO);
+                               nsh->dev[i].page = p;
+                               if (!p)
+                                       err = -ENOMEM;
+                       }
+               release_stripe(nsh);
+       }
+       /* critical section pass, GFP_NOIO no longer needed */
+
+       conf->slab_cache = sc;
+       conf->active_name = 1-conf->active_name;
+       conf->pool_size = newsize;
+       return err;
+}
+#endif
+
+static int drop_one_stripe(raid5_conf_t *conf)
+{
+       struct stripe_head *sh;
+
+       spin_lock_irq(&conf->device_lock);
+       sh = get_free_stripe(conf);
+       spin_unlock_irq(&conf->device_lock);
+       if (!sh)
+               return 0;
+       BUG_ON(atomic_read(&sh->count));
+       shrink_buffers(sh, conf->pool_size);
+       kmem_cache_free(conf->slab_cache, sh);
+       atomic_dec(&conf->active_stripes);
+       return 1;
+}
+
+static void shrink_stripes(raid5_conf_t *conf)
+{
+       while (drop_one_stripe(conf))
+               ;
+
+       if (conf->slab_cache)
+               kmem_cache_destroy(conf->slab_cache);
        conf->slab_cache = NULL;
 }
 
-static int raid5_end_read_request (struct bio * bi, unsigned int bytes_done,
+static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done,
                                   int error)
 {
        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)
@@ -391,10 +529,36 @@ static int raid5_end_read_request (struct bio * bi, unsigned int bytes_done,
                }
 #else
                set_bit(R5_UPTODATE, &sh->dev[i].flags);
-#endif         
+#endif
+               if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
+                       printk(KERN_INFO "raid5: read error corrected!!\n");
+                       clear_bit(R5_ReadError, &sh->dev[i].flags);
+                       clear_bit(R5_ReWrite, &sh->dev[i].flags);
+               }
+               if (atomic_read(&conf->disks[i].rdev->read_errors))
+                       atomic_set(&conf->disks[i].rdev->read_errors, 0);
        } else {
-               md_error(conf->mddev, conf->disks[i].rdev);
+               int retry = 0;
                clear_bit(R5_UPTODATE, &sh->dev[i].flags);
+               atomic_inc(&conf->disks[i].rdev->read_errors);
+               if (conf->mddev->degraded)
+                       printk(KERN_WARNING "raid5: read error not correctable.\n");
+               else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
+                       /* Oh, no!!! */
+                       printk(KERN_WARNING "raid5: read error NOT corrected!!\n");
+               else if (atomic_read(&conf->disks[i].rdev->read_errors)
+                        > conf->max_nr_stripes)
+                       printk(KERN_WARNING
+                              "raid5: Too many read errors, failing device.\n");
+               else
+                       retry = 1;
+               if (retry)
+                       set_bit(R5_ReadError, &sh->dev[i].flags);
+               else {
+                       clear_bit(R5_ReadError, &sh->dev[i].flags);
+                       clear_bit(R5_ReWrite, &sh->dev[i].flags);
+                       md_error(conf->mddev, conf->disks[i].rdev);
+               }
        }
        rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
 #if 0
@@ -416,7 +580,7 @@ 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);
 
@@ -477,19 +641,19 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
        raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
        PRINTK("raid5: error called\n");
 
-       if (!rdev->faulty) {
+       if (!test_bit(Faulty, &rdev->flags)) {
                mddev->sb_dirty = 1;
-               if (rdev->in_sync) {
+               if (test_bit(In_sync, &rdev->flags)) {
                        conf->working_disks--;
                        mddev->degraded++;
                        conf->failed_disks++;
-                       rdev->in_sync = 0;
+                       clear_bit(In_sync, &rdev->flags);
                        /*
                         * if recovery was running, make sure it aborts.
                         */
                        set_bit(MD_RECOVERY_ERR, &mddev->recovery);
                }
-               rdev->faulty = 1;
+               set_bit(Faulty, &rdev->flags);
                printk (KERN_ALERT
                        "raid5: Disk failure on %s, disabling device."
                        " Operation continuing on %d devices\n",
@@ -555,7 +719,7 @@ static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
                        *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
                        break;
                default:
-                       printk("raid5: unsupported algorithm %d\n",
+                       printk(KERN_ERR "raid5: unsupported algorithm %d\n",
                                conf->algorithm);
        }
 
@@ -570,7 +734,7 @@ 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;
@@ -596,7 +760,7 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
                        i -= (sh->pd_idx + 1);
                        break;
                default:
-                       printk("raid5: unsupported algorithm %d\n",
+                       printk(KERN_ERR "raid5: unsupported algorithm %d\n",
                                conf->algorithm);
        }
 
@@ -605,7 +769,7 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 
        check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
        if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
-               printk("compute_blocknr: map not correct\n");
+               printk(KERN_ERR "compute_blocknr: map not correct\n");
                return 0;
        }
        return r_sector;
@@ -671,8 +835,7 @@ 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", 
@@ -688,7 +851,7 @@ static void compute_block(struct stripe_head *sh, int dd_idx)
                if (test_bit(R5_UPTODATE, &sh->dev[i].flags))
                        ptr[count++] = p;
                else
-                       printk("compute_block() %d, stripe %llu, %d"
+                       printk(KERN_ERR "compute_block() %d, stripe %llu, %d"
                                " not present\n", dd_idx,
                                (unsigned long long)sh->sector, i);
 
@@ -702,7 +865,7 @@ 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;
 
@@ -713,8 +876,7 @@ static void compute_parity(struct stripe_head *sh, int method)
        ptr[0] = page_address(sh->dev[pd_idx].page);
        switch(method) {
        case READ_MODIFY_WRITE:
-               if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags))
-                       BUG();
+               BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags));
                for (i=disks ; i-- ;) {
                        if (i==pd_idx)
                                continue;
@@ -727,7 +889,7 @@ static void compute_parity(struct stripe_head *sh, int method)
                                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
                                        wake_up(&conf->wait_for_overlap);
 
-                               if (sh->dev[i].written) BUG();
+                               BUG_ON(sh->dev[i].written);
                                sh->dev[i].written = chosen;
                                check_xor();
                        }
@@ -743,7 +905,7 @@ static void compute_parity(struct stripe_head *sh, int method)
                                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
                                        wake_up(&conf->wait_for_overlap);
 
-                               if (sh->dev[i].written) BUG();
+                               BUG_ON(sh->dev[i].written);
                                sh->dev[i].written = chosen;
                        }
                break;
@@ -803,6 +965,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 {
        struct bio **bip;
        raid5_conf_t *conf = sh->raid_conf;
+       int firstwrite=0;
 
        PRINTK("adding bh b#%llu to stripe s#%llu\n",
                (unsigned long long)bi->bi_sector,
@@ -811,9 +974,11 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 
        spin_lock(&sh->lock);
        spin_lock_irq(&conf->device_lock);
-       if (forwrite)
+       if (forwrite) {
                bip = &sh->dev[dd_idx].towrite;
-       else
+               if (*bip == NULL && sh->dev[dd_idx].written == NULL)
+                       firstwrite = 1;
+       } else
                bip = &sh->dev[dd_idx].toread;
        while (*bip && (*bip)->bi_sector < bi->bi_sector) {
                if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
@@ -823,8 +988,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
        if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
                goto overlap;
 
-       if (*bip && bi->bi_next && (*bip) != bi->bi_next)
-               BUG();
+       BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
        if (*bip)
                bi->bi_next = *bip;
        *bip = bi;
@@ -836,6 +1000,13 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
                (unsigned long long)bi->bi_sector,
                (unsigned long long)sh->sector, dd_idx);
 
+       if (conf->mddev->bitmap && firstwrite) {
+               sh->bm_seq = conf->seq_write;
+               bitmap_startwrite(conf->mddev->bitmap, sh->sector,
+                                 STRIPE_SECTORS, 0);
+               set_bit(STRIPE_BIT_DELAY, &sh->state);
+       }
+
        if (forwrite) {
                /* check if page is covered */
                sector_t sector = sh->dev[dd_idx].sector;
@@ -858,6 +1029,20 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
        return 0;
 }
 
+static void end_reshape(raid5_conf_t *conf);
+
+static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
+{
+       int sectors_per_chunk = conf->chunk_size >> 9;
+       sector_t x = stripe;
+       int pd_idx, dd_idx;
+       int chunk_offset = sector_div(x, sectors_per_chunk);
+       stripe = x;
+       raid5_compute_sector(stripe*(disks-1)*sectors_per_chunk
+                            + chunk_offset, disks, disks-1, &dd_idx, &pd_idx, conf);
+       return pd_idx;
+}
+
 
 /*
  * handle_stripe - do things to a stripe.
@@ -880,11 +1065,11 @@ 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;
-       int syncing;
+       int syncing, expanding, expanded;
        int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
        int non_overwrite = 0;
        int failed_num=0;
@@ -899,13 +1084,15 @@ static void handle_stripe(struct stripe_head *sh)
        clear_bit(STRIPE_DELAYED, &sh->state);
 
        syncing = test_bit(STRIPE_SYNCING, &sh->state);
+       expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
+       expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
        /* Now to look around and see what can be done */
 
+       rcu_read_lock();
        for (i=disks; i--; ) {
                mdk_rdev_t *rdev;
                dev = &sh->dev[i];
                clear_bit(R5_Insync, &dev->flags);
-               clear_bit(R5_Syncio, &dev->flags);
 
                PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
                        i, dev->flags, dev->toread, dev->towrite, dev->written);
@@ -944,13 +1131,20 @@ static void handle_stripe(struct stripe_head *sh)
                                non_overwrite++;
                }
                if (dev->written) written++;
-               rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
-               if (!rdev || !rdev->in_sync) {
+               rdev = rcu_dereference(conf->disks[i].rdev);
+               if (!rdev || !test_bit(In_sync, &rdev->flags)) {
+                       /* The ReadError flag will just be confusing now */
+                       clear_bit(R5_ReadError, &dev->flags);
+                       clear_bit(R5_ReWrite, &dev->flags);
+               }
+               if (!rdev || !test_bit(In_sync, &rdev->flags)
+                   || test_bit(R5_ReadError, &dev->flags)) {
                        failed++;
                        failed_num = i;
                } else
                        set_bit(R5_Insync, &dev->flags);
        }
+       rcu_read_unlock();
        PRINTK("locked=%d uptodate=%d to_read=%d"
                " to_write=%d failed=%d failed_num=%d\n",
                locked, uptodate, to_read, to_write, failed, failed_num);
@@ -958,12 +1152,24 @@ static void handle_stripe(struct stripe_head *sh)
         * need to be failed
         */
        if (failed > 1 && to_read+to_write+written) {
-               spin_lock_irq(&conf->device_lock);
                for (i=disks; i--; ) {
+                       int bitmap_end = 0;
+
+                       if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
+                               mdk_rdev_t *rdev;
+                               rcu_read_lock();
+                               rdev = rcu_dereference(conf->disks[i].rdev);
+                               if (rdev && test_bit(In_sync, &rdev->flags))
+                                       /* multiple read failures in one stripe */
+                                       md_error(conf->mddev, rdev);
+                               rcu_read_unlock();
+                       }
+
+                       spin_lock_irq(&conf->device_lock);
                        /* fail all writes first */
                        bi = sh->dev[i].towrite;
                        sh->dev[i].towrite = NULL;
-                       if (bi) to_write--;
+                       if (bi) { to_write--; bitmap_end = 1; }
 
                        if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
                                wake_up(&conf->wait_for_overlap);
@@ -981,6 +1187,7 @@ static void handle_stripe(struct stripe_head *sh)
                        /* and fail all 'written' */
                        bi = sh->dev[i].written;
                        sh->dev[i].written = NULL;
+                       if (bi) bitmap_end = 1;
                        while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) {
                                struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
                                clear_bit(BIO_UPTODATE, &bi->bi_flags);
@@ -993,7 +1200,8 @@ static void handle_stripe(struct stripe_head *sh)
                        }
 
                        /* fail any reads if this device is non-operational */
-                       if (!test_bit(R5_Insync, &sh->dev[i].flags)) {
+                       if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
+                           test_bit(R5_ReadError, &sh->dev[i].flags)) {
                                bi = sh->dev[i].toread;
                                sh->dev[i].toread = NULL;
                                if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
@@ -1009,8 +1217,11 @@ static void handle_stripe(struct stripe_head *sh)
                                        bi = nextbi;
                                }
                        }
+                       spin_unlock_irq(&conf->device_lock);
+                       if (bitmap_end)
+                               bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+                                               STRIPE_SECTORS, 0, 0);
                }
-               spin_unlock_irq(&conf->device_lock);
        }
        if (failed > 1 && syncing) {
                md_done_sync(conf->mddev, STRIPE_SECTORS,0);
@@ -1038,6 +1249,7 @@ static void handle_stripe(struct stripe_head *sh)
                         test_bit(R5_UPTODATE, &dev->flags) ) {
                        /* We can return any write requests */
                            struct bio *wbi, *wbi2;
+                           int bitmap_end = 0;
                            PRINTK("Return write for disc %d\n", i);
                            spin_lock_irq(&conf->device_lock);
                            wbi = dev->written;
@@ -1051,7 +1263,13 @@ static void handle_stripe(struct stripe_head *sh)
                                    }
                                    wbi = wbi2;
                            }
+                           if (dev->towrite == NULL)
+                                   bitmap_end = 1;
                            spin_unlock_irq(&conf->device_lock);
+                           if (bitmap_end)
+                                   bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+                                                   STRIPE_SECTORS,
+                                                   !test_bit(STRIPE_DEGRADED, &sh->state), 0);
                    }
                }
        }
@@ -1060,13 +1278,14 @@ static void handle_stripe(struct stripe_head *sh)
         * parity, or to satisfy requests
         * or to load a block that is being partially written.
         */
-       if (to_read || non_overwrite || (syncing && (uptodate < disks))) {
+       if (to_read || non_overwrite || (syncing && (uptodate < disks)) || expanding) {
                for (i=disks; i--;) {
                        dev = &sh->dev[i];
                        if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
                            (dev->toread ||
                             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
                             syncing ||
+                            expanding ||
                             (failed && (sh->dev[failed_num].toread ||
                                         (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
                                    )
@@ -1093,9 +1312,6 @@ static void handle_stripe(struct stripe_head *sh)
                                        locked++;
                                        PRINTK("Reading block %d (sync=%d)\n", 
                                                i, syncing);
-                                       if (syncing)
-                                               md_sync_acct(conf->disks[i].rdev->bdev,
-                                                            STRIPE_SECTORS);
                                }
                        }
                }
@@ -1175,7 +1391,8 @@ static void handle_stripe(struct stripe_head *sh)
                                }
                        }
                /* now if nothing is locked, and if we have enough data, we can start a write request */
-               if (locked == 0 && (rcw == 0 ||rmw == 0)) {
+               if (locked == 0 && (rcw == 0 ||rmw == 0) &&
+                   !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
                        PRINTK("Computing parity...\n");
                        compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE);
                        /* now every locked buffer is ready to be written */
@@ -1201,12 +1418,11 @@ static void handle_stripe(struct stripe_head *sh)
         * is available
         */
        if (syncing && locked == 0 &&
-           !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 1) {
+           !test_bit(STRIPE_INSYNC, &sh->state)) {
                set_bit(STRIPE_HANDLE, &sh->state);
                if (failed == 0) {
                        char *pagea;
-                       if (uptodate != disks)
-                               BUG();
+                       BUG_ON(uptodate != disks);
                        compute_parity(sh, CHECK_PARITY);
                        uptodate--;
                        pagea = page_address(sh->dev[sh->pd_idx].page);
@@ -1214,33 +1430,121 @@ static void handle_stripe(struct stripe_head *sh)
                            !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) {
                                /* parity is correct (on disc, not in buffer any more) */
                                set_bit(STRIPE_INSYNC, &sh->state);
+                       } else {
+                               conf->mddev->resync_mismatches += STRIPE_SECTORS;
+                               if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
+                                       /* don't try to repair!! */
+                                       set_bit(STRIPE_INSYNC, &sh->state);
+                               else {
+                                       compute_block(sh, sh->pd_idx);
+                                       uptodate++;
+                               }
                        }
                }
                if (!test_bit(STRIPE_INSYNC, &sh->state)) {
+                       /* either failed parity check, or recovery is happening */
                        if (failed==0)
                                failed_num = sh->pd_idx;
-                       /* should be able to compute the missing block and write it to spare */
-                       if (!test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)) {
-                               if (uptodate+1 != disks)
-                                       BUG();
-                               compute_block(sh, failed_num);
-                               uptodate++;
-                       }
-                       if (uptodate != disks)
-                               BUG();
                        dev = &sh->dev[failed_num];
+                       BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
+                       BUG_ON(uptodate != disks);
+
                        set_bit(R5_LOCKED, &dev->flags);
                        set_bit(R5_Wantwrite, &dev->flags);
+                       clear_bit(STRIPE_DEGRADED, &sh->state);
                        locked++;
                        set_bit(STRIPE_INSYNC, &sh->state);
-                       set_bit(R5_Syncio, &dev->flags);
                }
        }
        if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
                md_done_sync(conf->mddev, STRIPE_SECTORS,1);
                clear_bit(STRIPE_SYNCING, &sh->state);
        }
-       
+
+       /* If the failed drive is just a ReadError, then we might need to progress
+        * the repair/check process
+        */
+       if (failed == 1 && ! conf->mddev->ro &&
+           test_bit(R5_ReadError, &sh->dev[failed_num].flags)
+           && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)
+           && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)
+               ) {
+               dev = &sh->dev[failed_num];
+               if (!test_bit(R5_ReWrite, &dev->flags)) {
+                       set_bit(R5_Wantwrite, &dev->flags);
+                       set_bit(R5_ReWrite, &dev->flags);
+                       set_bit(R5_LOCKED, &dev->flags);
+                       locked++;
+               } else {
+                       /* let's read it back */
+                       set_bit(R5_Wantread, &dev->flags);
+                       set_bit(R5_LOCKED, &dev->flags);
+                       locked++;
+               }
+       }
+
+       if (expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
+               /* Need to write out all blocks after computing parity */
+               sh->disks = conf->raid_disks;
+               sh->pd_idx = stripe_to_pdidx(sh->sector, conf, conf->raid_disks);
+               compute_parity(sh, RECONSTRUCT_WRITE);
+               for (i= conf->raid_disks; i--;) {
+                       set_bit(R5_LOCKED, &sh->dev[i].flags);
+                       locked++;
+                       set_bit(R5_Wantwrite, &sh->dev[i].flags);
+               }
+               clear_bit(STRIPE_EXPANDING, &sh->state);
+       } else if (expanded) {
+               clear_bit(STRIPE_EXPAND_READY, &sh->state);
+               atomic_dec(&conf->reshape_stripes);
+               wake_up(&conf->wait_for_overlap);
+               md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
+       }
+
+       if (expanding && locked == 0) {
+               /* We have read all the blocks in this stripe and now we need to
+                * copy some of them into a target stripe for expand.
+                */
+               clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
+               for (i=0; i< sh->disks; i++)
+                       if (i != sh->pd_idx) {
+                               int dd_idx, pd_idx, j;
+                               struct stripe_head *sh2;
+
+                               sector_t bn = compute_blocknr(sh, i);
+                               sector_t s = raid5_compute_sector(bn, conf->raid_disks,
+                                                                 conf->raid_disks-1,
+                                                                 &dd_idx, &pd_idx, conf);
+                               sh2 = get_active_stripe(conf, s, conf->raid_disks, pd_idx, 1);
+                               if (sh2 == NULL)
+                                       /* so far only the early blocks of this stripe
+                                        * have been requested.  When later blocks
+                                        * get requested, we will try again
+                                        */
+                                       continue;
+                               if(!test_bit(STRIPE_EXPANDING, &sh2->state) ||
+                                  test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
+                                       /* must have already done this block */
+                                       release_stripe(sh2);
+                                       continue;
+                               }
+                               memcpy(page_address(sh2->dev[dd_idx].page),
+                                      page_address(sh->dev[i].page),
+                                      STRIPE_SIZE);
+                               set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
+                               set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
+                               for (j=0; j<conf->raid_disks; j++)
+                                       if (j != sh2->pd_idx &&
+                                           !test_bit(R5_Expanded, &sh2->dev[j].flags))
+                                               break;
+                               if (j == conf->raid_disks) {
+                                       set_bit(STRIPE_EXPAND_READY, &sh2->state);
+                                       set_bit(STRIPE_HANDLE, &sh2->state);
+                               }
+                               release_stripe(sh2);
+                       }
+       }
+
        spin_unlock(&sh->lock);
 
        while ((bi=return_bi)) {
@@ -1271,15 +1575,15 @@ static void handle_stripe(struct stripe_head *sh)
                        bi->bi_end_io = raid5_end_read_request;
  
                rcu_read_lock();
-               rdev = conf->disks[i].rdev;
-               if (rdev && rdev->faulty)
+               rdev = rcu_dereference(conf->disks[i].rdev);
+               if (rdev && test_bit(Faulty, &rdev->flags))
                        rdev = NULL;
                if (rdev)
                        atomic_inc(&rdev->nr_pending);
                rcu_read_unlock();
  
                if (rdev) {
-                       if (test_bit(R5_Syncio, &sh->dev[i].flags))
+                       if (syncing || expanding || expanded)
                                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 
                        bi->bi_bdev = rdev->bdev;
@@ -1296,8 +1600,13 @@ static void handle_stripe(struct stripe_head *sh)
                        bi->bi_io_vec[0].bv_offset = 0;
                        bi->bi_size = STRIPE_SIZE;
                        bi->bi_next = NULL;
+                       if (rw == WRITE &&
+                           test_bit(R5_ReWrite, &sh->dev[i].flags))
+                               atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
                        generic_make_request(bi);
                } else {
+                       if (rw == 1)
+                               set_bit(STRIPE_DEGRADED, &sh->state);
                        PRINTK("skip op %ld on disc %d for sector %llu\n",
                                bi->bi_rw, i, (unsigned long long)sh->sector);
                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
@@ -1306,7 +1615,7 @@ static void handle_stripe(struct stripe_head *sh)
        }
 }
 
-static inline void raid5_activate_delayed(raid5_conf_t *conf)
+static void raid5_activate_delayed(raid5_conf_t *conf)
 {
        if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
                while (!list_empty(&conf->delayed_list)) {
@@ -1322,6 +1631,20 @@ static inline void raid5_activate_delayed(raid5_conf_t *conf)
        }
 }
 
+static void activate_bit_delay(raid5_conf_t *conf)
+{
+       /* device_lock is held */
+       struct list_head head;
+       list_add(&head, &conf->bitmap_list);
+       list_del_init(&conf->bitmap_list);
+       while (!list_empty(&head)) {
+               struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
+               list_del_init(&sh->lru);
+               atomic_inc(&sh->count);
+               __release_stripe(conf, sh);
+       }
+}
+
 static void unplug_slaves(mddev_t *mddev)
 {
        raid5_conf_t *conf = mddev_to_conf(mddev);
@@ -1329,8 +1652,8 @@ static void unplug_slaves(mddev_t *mddev)
 
        rcu_read_lock();
        for (i=0; i<mddev->raid_disks; i++) {
-               mdk_rdev_t *rdev = conf->disks[i].rdev;
-               if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
+               mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
+               if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
                        request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
 
                        atomic_inc(&rdev->nr_pending);
@@ -1354,8 +1677,10 @@ static void raid5_unplug_device(request_queue_t *q)
 
        spin_lock_irqsave(&conf->device_lock, flags);
 
-       if (blk_remove_plug(q))
+       if (blk_remove_plug(q)) {
+               conf->seq_flush++;
                raid5_activate_delayed(conf);
+       }
        md_wakeup_thread(mddev->thread);
 
        spin_unlock_irqrestore(&conf->device_lock, flags);
@@ -1372,8 +1697,8 @@ static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk,
 
        rcu_read_lock();
        for (i=0; i<mddev->raid_disks && ret == 0; i++) {
-               mdk_rdev_t *rdev = conf->disks[i].rdev;
-               if (rdev && !rdev->faulty) {
+               mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
+               if (rdev && !test_bit(Faulty, &rdev->flags)) {
                        struct block_device *bdev = rdev->bdev;
                        request_queue_t *r_queue = bdev_get_queue(bdev);
 
@@ -1400,47 +1725,105 @@ 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;
        struct stripe_head *sh;
+       const int rw = bio_data_dir(bi);
+       int remaining;
 
-       if (bio_data_dir(bi)==WRITE) {
-               disk_stat_inc(mddev->gendisk, writes);
-               disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
-       } else {
-               disk_stat_inc(mddev->gendisk, reads);
-               disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi));
+       if (unlikely(bio_barrier(bi))) {
+               bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
+               return 0;
        }
 
+       md_write_start(mddev, bi);
+
+       disk_stat_inc(mddev->gendisk, ios[rw]);
+       disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bi));
+
        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
        last_sector = bi->bi_sector + (bi->bi_size>>9);
        bi->bi_next = NULL;
        bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
-       if ( bio_data_dir(bi) == WRITE )
-               md_write_start(mddev);
+
        for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
                DEFINE_WAIT(w);
-               
-               new_sector = raid5_compute_sector(logical_sector,
-                                                 raid_disks, data_disks, &dd_idx, &pd_idx, conf);
+               int disks;
 
+       retry:
+               prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
+               if (likely(conf->expand_progress == MaxSector))
+                       disks = conf->raid_disks;
+               else {
+                       /* spinlock is needed as expand_progress may be
+                        * 64bit on a 32bit platform, and so it might be
+                        * possible to see a half-updated value
+                        * Ofcourse expand_progress could change after
+                        * the lock is dropped, so once we get a reference
+                        * to the stripe that we think it is, we will have
+                        * to check again.
+                        */
+                       spin_lock_irq(&conf->device_lock);
+                       disks = conf->raid_disks;
+                       if (logical_sector >= conf->expand_progress)
+                               disks = conf->previous_raid_disks;
+                       else {
+                               if (logical_sector >= conf->expand_lo) {
+                                       spin_unlock_irq(&conf->device_lock);
+                                       schedule();
+                                       goto retry;
+                               }
+                       }
+                       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 must do the range check again.
+                                * Expansion could still move past after this
+                                * test, but as we are holding a reference to
+                                * 'sh', we know that if that happens,
+                                *  STRIPE_EXPANDING will get set and the expansion
+                                * won't proceed until we finish with the stripe.
+                                */
+                               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;
+                               }
+                       }
+                       /* FIXME what if we get a false positive because these
+                        * are being updated.
+                        */
+                       if (logical_sector >= mddev->suspend_lo &&
+                           logical_sector < mddev->suspend_hi) {
+                               release_stripe(sh);
+                               schedule();
+                               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);
@@ -1452,7 +1835,6 @@ 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);
@@ -1462,7 +1844,9 @@ static int make_request (request_queue_t *q, struct bio * bi)
                        
        }
        spin_lock_irq(&conf->device_lock);
-       if (--bi->bi_phys_segments == 0) {
+       remaining = --bi->bi_phys_segments;
+       spin_unlock_irq(&conf->device_lock);
+       if (remaining == 0) {
                int bytes = bi->bi_size;
 
                if ( bio_data_dir(bi) == WRITE )
@@ -1470,55 +1854,183 @@ static int make_request (request_queue_t *q, struct bio * bi)
                bi->bi_size = 0;
                bi->bi_end_io(bi, bytes, 0);
        }
-       spin_unlock_irq(&conf->device_lock);
        return 0;
 }
 
 /* FIXME go_faster isn't used */
-static int sync_request (mddev_t *mddev, sector_t sector_nr, int go_faster)
+static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
 {
        raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
        struct stripe_head *sh;
-       int sectors_per_chunk = conf->chunk_size >> 9;
-       sector_t x;
-       unsigned long stripe;
-       int chunk_offset;
-       int dd_idx, pd_idx;
-       sector_t first_sector;
+       int pd_idx;
+       sector_t first_sector, last_sector;
        int raid_disks = conf->raid_disks;
        int data_disks = raid_disks-1;
+       sector_t max_sector = mddev->size << 1;
+       int sync_blocks;
 
-       if (sector_nr >= mddev->size <<1) {
+       if (sector_nr >= max_sector) {
                /* just being told to finish up .. nothing much to do */
                unplug_slaves(mddev);
+               if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
+                       end_reshape(conf);
+                       return 0;
+               }
+
+               if (mddev->curr_resync < max_sector) /* aborted */
+                       bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
+                                       &sync_blocks, 1);
+               else /* compelted sync */
+                       conf->fullsync = 0;
+               bitmap_close_sync(mddev->bitmap);
+
                return 0;
        }
+
+       if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
+               /* reshaping is quite different to recovery/resync so it is
+                * handled quite separately ... here.
+                *
+                * On each call to sync_request, we gather one chunk worth of
+                * destination stripes and flag them as expanding.
+                * Then we find all the source stripes and request reads.
+                * As the reads complete, handle_stripe will copy the data
+                * into the destination stripe and release that stripe.
+                */
+               int i;
+               int dd_idx;
+               sector_t writepos, safepos, gap;
+
+               if (sector_nr == 0 &&
+                   conf->expand_progress != 0) {
+                       /* restarting in the middle, skip the initial sectors */
+                       sector_nr = conf->expand_progress;
+                       sector_div(sector_nr, conf->raid_disks-1);
+                       *skipped = 1;
+                       return sector_nr;
+               }
+
+               /* we update the metadata when there is more than 3Meg
+                * in the block range (that is rather arbitrary, should
+                * probably be time based) or when the data about to be
+                * copied would over-write the source of the data at
+                * the front of the range.
+                * i.e. one new_stripe forward from expand_progress new_maps
+                * to after where expand_lo old_maps to
+                */
+               writepos = conf->expand_progress +
+                       conf->chunk_size/512*(conf->raid_disks-1);
+               sector_div(writepos, conf->raid_disks-1);
+               safepos = conf->expand_lo;
+               sector_div(safepos, conf->previous_raid_disks-1);
+               gap = conf->expand_progress - conf->expand_lo;
+
+               if (writepos >= safepos ||
+                   gap > (conf->raid_disks-1)*3000*2 /*3Meg*/) {
+                       /* Cannot proceed until we've updated the superblock... */
+                       wait_event(conf->wait_for_overlap,
+                                  atomic_read(&conf->reshape_stripes)==0);
+                       mddev->reshape_position = conf->expand_progress;
+                       mddev->sb_dirty = 1;
+                       md_wakeup_thread(mddev->thread);
+                       wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
+                                  kthread_should_stop());
+                       spin_lock_irq(&conf->device_lock);
+                       conf->expand_lo = mddev->reshape_position;
+                       spin_unlock_irq(&conf->device_lock);
+                       wake_up(&conf->wait_for_overlap);
+               }
+
+               for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
+                       int j;
+                       int skipped = 0;
+                       pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
+                       sh = get_active_stripe(conf, sector_nr+i,
+                                              conf->raid_disks, pd_idx, 0);
+                       set_bit(STRIPE_EXPANDING, &sh->state);
+                       atomic_inc(&conf->reshape_stripes);
+                       /* If any of this stripe is beyond the end of the old
+                        * array, then we need to zero those blocks
+                        */
+                       for (j=sh->disks; j--;) {
+                               sector_t s;
+                               if (j == sh->pd_idx)
+                                       continue;
+                               s = compute_blocknr(sh, j);
+                               if (s < (mddev->array_size<<1)) {
+                                       skipped = 1;
+                                       continue;
+                               }
+                               memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
+                               set_bit(R5_Expanded, &sh->dev[j].flags);
+                               set_bit(R5_UPTODATE, &sh->dev[j].flags);
+                       }
+                       if (!skipped) {
+                               set_bit(STRIPE_EXPAND_READY, &sh->state);
+                               set_bit(STRIPE_HANDLE, &sh->state);
+                       }
+                       release_stripe(sh);
+               }
+               spin_lock_irq(&conf->device_lock);
+               conf->expand_progress = (sector_nr + i)*(conf->raid_disks-1);
+               spin_unlock_irq(&conf->device_lock);
+               /* Ok, those stripe are ready. We can start scheduling
+                * reads on the source stripes.
+                * The source stripes are determined by mapping the first and last
+                * block on the destination stripes.
+                */
+               raid_disks = conf->previous_raid_disks;
+               data_disks = raid_disks - 1;
+               first_sector =
+                       raid5_compute_sector(sector_nr*(conf->raid_disks-1),
+                                            raid_disks, data_disks,
+                                            &dd_idx, &pd_idx, conf);
+               last_sector =
+                       raid5_compute_sector((sector_nr+conf->chunk_size/512)
+                                              *(conf->raid_disks-1) -1,
+                                            raid_disks, data_disks,
+                                            &dd_idx, &pd_idx, conf);
+               if (last_sector >= (mddev->size<<1))
+                       last_sector = (mddev->size<<1)-1;
+               while (first_sector <= last_sector) {
+                       pd_idx = stripe_to_pdidx(first_sector, conf, conf->previous_raid_disks);
+                       sh = get_active_stripe(conf, first_sector,
+                                              conf->previous_raid_disks, pd_idx, 0);
+                       set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
+                       set_bit(STRIPE_HANDLE, &sh->state);
+                       release_stripe(sh);
+                       first_sector += STRIPE_SECTORS;
+               }
+               return conf->chunk_size>>9;
+       }
        /* if there is 1 or more failed drives and we are trying
         * to resync, then assert that we are finished, because there is
         * nothing we can do.
         */
        if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
-               int rv = (mddev->size << 1) - sector_nr;
-               md_done_sync(mddev, rv, 1);
+               sector_t rv = (mddev->size << 1) - sector_nr;
+               *skipped = 1;
                return rv;
        }
+       if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
+           !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
+           !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
+               /* we can skip this block, and probably more */
+               sync_blocks /= STRIPE_SECTORS;
+               *skipped = 1;
+               return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
+       }
 
-       x = sector_nr;
-       chunk_offset = sector_div(x, sectors_per_chunk);
-       stripe = x;
-       BUG_ON(x != stripe);
-
-       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);
+       pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
+       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 
                 */
-               set_current_state(TASK_UNINTERRUPTIBLE);
-               schedule_timeout(1);
+               schedule_timeout_uninterruptible(1);
        }
+       bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 0);
        spin_lock(&sh->lock);   
        set_bit(STRIPE_SYNCING, &sh->state);
        clear_bit(STRIPE_INSYNC, &sh->state);
@@ -1546,13 +2058,21 @@ static void raid5d (mddev_t *mddev)
        PRINTK("+++ raid5d active\n");
 
        md_check_recovery(mddev);
-       md_handle_safemode(mddev);
 
        handled = 0;
        spin_lock_irq(&conf->device_lock);
        while (1) {
                struct list_head *first;
 
+               if (conf->seq_flush - conf->seq_write > 0) {
+                       int seq = conf->seq_flush;
+                       spin_unlock_irq(&conf->device_lock);
+                       bitmap_unplug(mddev->bitmap);
+                       spin_lock_irq(&conf->device_lock);
+                       conf->seq_write = seq;
+                       activate_bit_delay(conf);
+               }
+
                if (list_empty(&conf->handle_list) &&
                    atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD &&
                    !blk_queue_plugged(mddev->queue) &&
@@ -1567,8 +2087,7 @@ static void raid5d (mddev_t *mddev)
 
                list_del_init(first);
                atomic_inc(&sh->count);
-               if (atomic_read(&sh->count)!= 1)
-                       BUG();
+               BUG_ON(atomic_read(&sh->count)!= 1);
                spin_unlock_irq(&conf->device_lock);
                
                handled++;
@@ -1586,7 +2105,75 @@ static void raid5d (mddev_t *mddev)
        PRINTK("--- raid5d inactive\n");
 }
 
-static int run (mddev_t *mddev)
+static ssize_t
+raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+       if (conf)
+               return sprintf(page, "%d\n", conf->max_nr_stripes);
+       else
+               return 0;
+}
+
+static ssize_t
+raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+       char *end;
+       int new;
+       if (len >= PAGE_SIZE)
+               return -EINVAL;
+       if (!conf)
+               return -ENODEV;
+
+       new = simple_strtoul(page, &end, 10);
+       if (!*page || (*end && *end != '\n') )
+               return -EINVAL;
+       if (new <= 16 || new > 32768)
+               return -EINVAL;
+       while (new < conf->max_nr_stripes) {
+               if (drop_one_stripe(conf))
+                       conf->max_nr_stripes--;
+               else
+                       break;
+       }
+       while (new > conf->max_nr_stripes) {
+               if (grow_one_stripe(conf))
+                       conf->max_nr_stripes++;
+               else break;
+       }
+       return len;
+}
+
+static struct md_sysfs_entry
+raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
+                               raid5_show_stripe_cache_size,
+                               raid5_store_stripe_cache_size);
+
+static ssize_t
+stripe_cache_active_show(mddev_t *mddev, char *page)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+       if (conf)
+               return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
+       else
+               return 0;
+}
+
+static struct md_sysfs_entry
+raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
+
+static struct attribute *raid5_attrs[] =  {
+       &raid5_stripecache_size.attr,
+       &raid5_stripecache_active.attr,
+       NULL,
+};
+static struct attribute_group raid5_attrs_group = {
+       .name = NULL,
+       .attrs = raid5_attrs,
+};
+
+static int run(mddev_t *mddev)
 {
        raid5_conf_t *conf;
        int raid_disk, memory;
@@ -1595,27 +2182,81 @@ static int run (mddev_t *mddev)
        struct list_head *tmp;
 
        if (mddev->level != 5 && mddev->level != 4) {
-               printk("raid5: %s: raid level not set to 4/5 (%d)\n", mdname(mddev), mddev->level);
+               printk(KERN_ERR "raid5: %s: raid level not set to 4/5 (%d)\n",
+                      mdname(mddev), mddev->level);
                return -EIO;
        }
 
-       mddev->private = kmalloc (sizeof (raid5_conf_t)
-                                 + mddev->raid_disks * sizeof(struct disk_info),
-                                 GFP_KERNEL);
+       if (mddev->reshape_position != MaxSector) {
+               /* Check that we can continue the reshape.
+                * Currently only disks can change, it must
+                * increase, and we must be past the point where
+                * a stripe over-writes itself
+                */
+               sector_t here_new, here_old;
+               int old_disks;
+
+               if (mddev->new_level != mddev->level ||
+                   mddev->new_layout != mddev->layout ||
+                   mddev->new_chunk != mddev->chunk_size) {
+                       printk(KERN_ERR "raid5: %s: unsupported reshape required - aborting.\n",
+                              mdname(mddev));
+                       return -EINVAL;
+               }
+               if (mddev->delta_disks <= 0) {
+                       printk(KERN_ERR "raid5: %s: unsupported reshape (reduce disks) required - aborting.\n",
+                              mdname(mddev));
+                       return -EINVAL;
+               }
+               old_disks = mddev->raid_disks - mddev->delta_disks;
+               /* reshape_position must be on a new-stripe boundary, and one
+                * further up in new geometry must map after here in old geometry.
+                */
+               here_new = mddev->reshape_position;
+               if (sector_div(here_new, (mddev->chunk_size>>9)*(mddev->raid_disks-1))) {
+                       printk(KERN_ERR "raid5: reshape_position not on a stripe boundary\n");
+                       return -EINVAL;
+               }
+               /* here_new is the stripe we will write to */
+               here_old = mddev->reshape_position;
+               sector_div(here_old, (mddev->chunk_size>>9)*(old_disks-1));
+               /* here_old is the first stripe that we might need to read from */
+               if (here_new >= here_old) {
+                       /* Reading from the same stripe as writing to - bad */
+                       printk(KERN_ERR "raid5: reshape_position too early for auto-recovery - aborting.\n");
+                       return -EINVAL;
+               }
+               printk(KERN_INFO "raid5: reshape will continue\n");
+               /* OK, we should be able to continue; */
+       }
+
+
+       mddev->private = kzalloc(sizeof (raid5_conf_t), GFP_KERNEL);
        if ((conf = mddev->private) == NULL)
                goto abort;
-       memset (conf, 0, sizeof (*conf) + mddev->raid_disks * sizeof(struct disk_info) );
+       if (mddev->reshape_position == MaxSector) {
+               conf->previous_raid_disks = conf->raid_disks = mddev->raid_disks;
+       } else {
+               conf->raid_disks = mddev->raid_disks;
+               conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
+       }
+
+       conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
+                             GFP_KERNEL);
+       if (!conf->disks)
+               goto abort;
+
        conf->mddev = mddev;
 
-       if ((conf->stripe_hashtbl = (struct stripe_head **) __get_free_pages(GFP_ATOMIC, HASH_PAGES_ORDER)) == NULL)
+       if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
                goto abort;
-       memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE);
 
        spin_lock_init(&conf->device_lock);
        init_waitqueue_head(&conf->wait_for_stripe);
        init_waitqueue_head(&conf->wait_for_overlap);
        INIT_LIST_HEAD(&conf->handle_list);
        INIT_LIST_HEAD(&conf->delayed_list);
+       INIT_LIST_HEAD(&conf->bitmap_list);
        INIT_LIST_HEAD(&conf->inactive_list);
        atomic_set(&conf->active_stripes, 0);
        atomic_set(&conf->preread_active_stripes, 0);
@@ -1624,14 +2265,14 @@ static int run (mddev_t *mddev)
 
        ITERATE_RDEV(mddev,rdev,tmp) {
                raid_disk = rdev->raid_disk;
-               if (raid_disk >= mddev->raid_disks
+               if (raid_disk >= conf->raid_disks
                    || raid_disk < 0)
                        continue;
                disk = conf->disks + raid_disk;
 
                disk->rdev = rdev;
 
-               if (rdev->in_sync) {
+               if (test_bit(In_sync, &rdev->flags)) {
                        char b[BDEVNAME_SIZE];
                        printk(KERN_INFO "raid5: device %s operational as raid"
                                " disk %d\n", bdevname(rdev->bdev,b),
@@ -1640,7 +2281,6 @@ static int run (mddev_t *mddev)
                }
        }
 
-       conf->raid_disks = mddev->raid_disks;
        /*
         * 0 for a fully functional array, 1 for a degraded array.
         */
@@ -1650,9 +2290,11 @@ static int run (mddev_t *mddev)
        conf->level = mddev->level;
        conf->algorithm = mddev->layout;
        conf->max_nr_stripes = NR_STRIPES;
+       conf->expand_progress = mddev->reshape_position;
 
        /* device size must be a multiple of chunk size */
        mddev->size &= ~(mddev->chunk_size/1024 -1);
+       mddev->resync_max_sectors = mddev->size << 1;
 
        if (!conf->chunk_size || conf->chunk_size % 4) {
                printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
@@ -1674,10 +2316,17 @@ static int run (mddev_t *mddev)
 
        if (mddev->degraded == 1 &&
            mddev->recovery_cp != MaxSector) {
-               printk(KERN_ERR 
-                       "raid5: cannot start dirty degraded array for %s\n",
-                       mdname(mddev));
-               goto abort;
+               if (mddev->ok_start_degraded)
+                       printk(KERN_WARNING
+                              "raid5: starting dirty degraded array: %s"
+                              "- data corruption possible.\n",
+                              mdname(mddev));
+               else {
+                       printk(KERN_ERR
+                              "raid5: cannot start dirty degraded array for %s\n",
+                              mdname(mddev));
+                       goto abort;
+               }
        }
 
        {
@@ -1689,7 +2338,7 @@ static int run (mddev_t *mddev)
                        goto abort;
                }
        }
-memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
+       memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
                 conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
        if (grow_stripes(conf, conf->max_nr_stripes)) {
                printk(KERN_ERR 
@@ -1714,29 +2363,44 @@ memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
 
        print_raid5_conf(conf);
 
+       if (conf->expand_progress != MaxSector) {
+               printk("...ok start reshape thread\n");
+               conf->expand_lo = conf->expand_progress;
+               atomic_set(&conf->reshape_stripes, 0);
+               clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+               clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+               set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+               set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+               mddev->sync_thread = md_register_thread(md_do_sync, mddev,
+                                                       "%s_reshape");
+               /* FIXME if md_register_thread fails?? */
+               md_wakeup_thread(mddev->sync_thread);
+
+       }
+
        /* read-ahead size must cover two whole stripes, which is
         * 2 * (n-1) * chunksize where 'n' is the number of raid devices
         */
        {
                int stripe = (mddev->raid_disks-1) * mddev->chunk_size
-                       / PAGE_CACHE_SIZE;
+                       / PAGE_SIZE;
                if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
                        mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
        }
 
        /* Ok, everything is just fine now */
+       sysfs_create_group(&mddev->kobj, &raid5_attrs_group);
 
        mddev->queue->unplug_fn = raid5_unplug_device;
        mddev->queue->issue_flush_fn = raid5_issue_flush;
+       mddev->array_size =  mddev->size * (conf->previous_raid_disks - 1);
 
-       mddev->array_size =  mddev->size * (mddev->raid_disks - 1);
        return 0;
 abort:
        if (conf) {
                print_raid5_conf(conf);
-               if (conf->stripe_hashtbl)
-                       free_pages((unsigned long) conf->stripe_hashtbl,
-                                                       HASH_PAGES_ORDER);
+               kfree(conf->disks);
+               kfree(conf->stripe_hashtbl);
                kfree(conf);
        }
        mddev->private = NULL;
@@ -1746,15 +2410,17 @@ abort:
 
 
 
-static int stop (mddev_t *mddev)
+static int stop(mddev_t *mddev)
 {
        raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
 
        md_unregister_thread(mddev->thread);
        mddev->thread = NULL;
        shrink_stripes(conf);
-       free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER);
+       kfree(conf->stripe_hashtbl);
        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+       sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
+       kfree(conf->disks);
        kfree(conf);
        mddev->private = NULL;
        return 0;
@@ -1770,7 +2436,7 @@ 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);
        }
@@ -1780,12 +2446,12 @@ static void print_sh (struct stripe_head *sh)
 static void printall (raid5_conf_t *conf)
 {
        struct stripe_head *sh;
+       struct hlist_node *hn;
        int i;
 
        spin_lock_irq(&conf->device_lock);
        for (i = 0; i < NR_HASH; i++) {
-               sh = conf->stripe_hashtbl[i];
-               for (; sh; sh = sh->hash_next) {
+               hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
                        if (sh->raid_conf != conf)
                                continue;
                        print_sh(sh);
@@ -1805,7 +2471,7 @@ static void status (struct seq_file *seq, mddev_t *mddev)
        for (i = 0; i < conf->raid_disks; i++)
                seq_printf (seq, "%s",
                               conf->disks[i].rdev &&
-                              conf->disks[i].rdev->in_sync ? "U" : "_");
+                              test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
        seq_printf (seq, "]");
 #if RAID5_DEBUG
 #define D(x) \
@@ -1832,7 +2498,7 @@ static void print_raid5_conf (raid5_conf_t *conf)
                tmp = conf->disks + i;
                if (tmp->rdev)
                printk(" disk %d, o:%d, dev:%s\n",
-                       i, !tmp->rdev->faulty,
+                       i, !test_bit(Faulty, &tmp->rdev->flags),
                        bdevname(tmp->rdev->bdev,b));
        }
 }
@@ -1846,12 +2512,12 @@ static int raid5_spare_active(mddev_t *mddev)
        for (i = 0; i < conf->raid_disks; i++) {
                tmp = conf->disks + i;
                if (tmp->rdev
-                   && !tmp->rdev->faulty
-                   && !tmp->rdev->in_sync) {
+                   && !test_bit(Faulty, &tmp->rdev->flags)
+                   && !test_bit(In_sync, &tmp->rdev->flags)) {
                        mddev->degraded--;
                        conf->failed_disks--;
                        conf->working_disks++;
-                       tmp->rdev->in_sync = 1;
+                       set_bit(In_sync, &tmp->rdev->flags);
                }
        }
        print_raid5_conf(conf);
@@ -1868,7 +2534,7 @@ static int raid5_remove_disk(mddev_t *mddev, int number)
        print_raid5_conf(conf);
        rdev = p->rdev;
        if (rdev) {
-               if (rdev->in_sync ||
+               if (test_bit(In_sync, &rdev->flags) ||
                    atomic_read(&rdev->nr_pending)) {
                        err = -EBUSY;
                        goto abort;
@@ -1901,12 +2567,14 @@ static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
        /*
         * find the disk ...
         */
-       for (disk=0; disk < mddev->raid_disks; disk++)
+       for (disk=0; disk < conf->raid_disks; disk++)
                if ((p=conf->disks + disk)->rdev == NULL) {
-                       rdev->in_sync = 0;
+                       clear_bit(In_sync, &rdev->flags);
                        rdev->raid_disk = disk;
                        found = 1;
-                       p->rdev = rdev;
+                       if (rdev->saved_raid_disk != disk)
+                               conf->fullsync = 1;
+                       rcu_assign_pointer(p->rdev, rdev);
                        break;
                }
        print_raid5_conf(conf);
@@ -1931,12 +2599,195 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        }
        mddev->size = sectors /2;
+       mddev->resync_max_sectors = sectors;
        return 0;
 }
 
-static mdk_personality_t raid5_personality=
+#ifdef CONFIG_MD_RAID5_RESHAPE
+static int raid5_check_reshape(mddev_t *mddev)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+       int err;
+
+       if (mddev->delta_disks < 0 ||
+           mddev->new_level != mddev->level)
+               return -EINVAL; /* Cannot shrink array or change level yet */
+       if (mddev->delta_disks == 0)
+               return 0; /* nothing to do */
+
+       /* Can only proceed if there are plenty of stripe_heads.
+        * We need a minimum of one full stripe,, and for sensible progress
+        * it is best to have about 4 times that.
+        * If we require 4 times, then the default 256 4K stripe_heads will
+        * allow for chunk sizes up to 256K, which is probably OK.
+        * If the chunk size is greater, user-space should request more
+        * stripe_heads first.
+        */
+       if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
+           (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
+               printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
+                      (mddev->chunk_size / STRIPE_SIZE)*4);
+               return -ENOSPC;
+       }
+
+       err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
+       if (err)
+               return err;
+
+       /* looks like we might be able to manage this */
+       return 0;
+}
+
+static int raid5_start_reshape(mddev_t *mddev)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+       mdk_rdev_t *rdev;
+       struct list_head *rtmp;
+       int spares = 0;
+       int added_devices = 0;
+
+       if (mddev->degraded ||
+           test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+               return -EBUSY;
+
+       ITERATE_RDEV(mddev, rdev, rtmp)
+               if (rdev->raid_disk < 0 &&
+                   !test_bit(Faulty, &rdev->flags))
+                       spares++;
+
+       if (spares < mddev->delta_disks-1)
+               /* Not enough devices even to make a degraded array
+                * of that size
+                */
+               return -EINVAL;
+
+       atomic_set(&conf->reshape_stripes, 0);
+       spin_lock_irq(&conf->device_lock);
+       conf->previous_raid_disks = conf->raid_disks;
+       conf->raid_disks += mddev->delta_disks;
+       conf->expand_progress = 0;
+       conf->expand_lo = 0;
+       spin_unlock_irq(&conf->device_lock);
+
+       /* Add some new drives, as many as will fit.
+        * We know there are enough to make the newly sized array work.
+        */
+       ITERATE_RDEV(mddev, rdev, rtmp)
+               if (rdev->raid_disk < 0 &&
+                   !test_bit(Faulty, &rdev->flags)) {
+                       if (raid5_add_disk(mddev, rdev)) {
+                               char nm[20];
+                               set_bit(In_sync, &rdev->flags);
+                               conf->working_disks++;
+                               added_devices++;
+                               sprintf(nm, "rd%d", rdev->raid_disk);
+                               sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
+                       } else
+                               break;
+               }
+
+       mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
+       mddev->raid_disks = conf->raid_disks;
+       mddev->reshape_position = 0;
+       mddev->sb_dirty = 1;
+
+       clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+       clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+       set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+       set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+       mddev->sync_thread = md_register_thread(md_do_sync, mddev,
+                                               "%s_reshape");
+       if (!mddev->sync_thread) {
+               mddev->recovery = 0;
+               spin_lock_irq(&conf->device_lock);
+               mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
+               conf->expand_progress = MaxSector;
+               spin_unlock_irq(&conf->device_lock);
+               return -EAGAIN;
+       }
+       md_wakeup_thread(mddev->sync_thread);
+       md_new_event(mddev);
+       return 0;
+}
+#endif
+
+static void end_reshape(raid5_conf_t *conf)
+{
+       struct block_device *bdev;
+
+       if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
+               conf->mddev->array_size = conf->mddev->size * (conf->raid_disks-1);
+               set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
+               conf->mddev->changed = 1;
+
+               bdev = bdget_disk(conf->mddev->gendisk, 0);
+               if (bdev) {
+                       mutex_lock(&bdev->bd_inode->i_mutex);
+                       i_size_write(bdev->bd_inode, conf->mddev->array_size << 10);
+                       mutex_unlock(&bdev->bd_inode->i_mutex);
+                       bdput(bdev);
+               }
+               spin_lock_irq(&conf->device_lock);
+               conf->expand_progress = MaxSector;
+               spin_unlock_irq(&conf->device_lock);
+               conf->mddev->reshape_position = MaxSector;
+       }
+}
+
+static void raid5_quiesce(mddev_t *mddev, int state)
+{
+       raid5_conf_t *conf = mddev_to_conf(mddev);
+
+       switch(state) {
+       case 2: /* resume for a suspend */
+               wake_up(&conf->wait_for_overlap);
+               break;
+
+       case 1: /* stop all writes */
+               spin_lock_irq(&conf->device_lock);
+               conf->quiesce = 1;
+               wait_event_lock_irq(conf->wait_for_stripe,
+                                   atomic_read(&conf->active_stripes) == 0,
+                                   conf->device_lock, /* nothing */);
+               spin_unlock_irq(&conf->device_lock);
+               break;
+
+       case 0: /* re-enable writes */
+               spin_lock_irq(&conf->device_lock);
+               conf->quiesce = 0;
+               wake_up(&conf->wait_for_stripe);
+               wake_up(&conf->wait_for_overlap);
+               spin_unlock_irq(&conf->device_lock);
+               break;
+       }
+}
+
+static struct mdk_personality raid5_personality =
 {
        .name           = "raid5",
+       .level          = 5,
+       .owner          = THIS_MODULE,
+       .make_request   = make_request,
+       .run            = run,
+       .stop           = stop,
+       .status         = status,
+       .error_handler  = error,
+       .hot_add_disk   = raid5_add_disk,
+       .hot_remove_disk= raid5_remove_disk,
+       .spare_active   = raid5_spare_active,
+       .sync_request   = sync_request,
+       .resize         = raid5_resize,
+#ifdef CONFIG_MD_RAID5_RESHAPE
+       .check_reshape  = raid5_check_reshape,
+       .start_reshape  = raid5_start_reshape,
+#endif
+       .quiesce        = raid5_quiesce,
+};
+
+static struct mdk_personality raid4_personality =
+{
+       .name           = "raid4",
+       .level          = 4,
        .owner          = THIS_MODULE,
        .make_request   = make_request,
        .run            = run,
@@ -1948,19 +2799,27 @@ static mdk_personality_t raid5_personality=
        .spare_active   = raid5_spare_active,
        .sync_request   = sync_request,
        .resize         = raid5_resize,
+       .quiesce        = raid5_quiesce,
 };
 
-static int __init raid5_init (void)
+static int __init raid5_init(void)
 {
-       return register_md_personality (RAID5, &raid5_personality);
+       register_md_personality(&raid5_personality);
+       register_md_personality(&raid4_personality);
+       return 0;
 }
 
-static void raid5_exit (void)
+static void raid5_exit(void)
 {
-       unregister_md_personality (RAID5);
+       unregister_md_personality(&raid5_personality);
+       unregister_md_personality(&raid4_personality);
 }
 
 module_init(raid5_init);
 module_exit(raid5_exit);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("md-personality-4"); /* RAID5 */
+MODULE_ALIAS("md-raid5");
+MODULE_ALIAS("md-raid4");
+MODULE_ALIAS("md-level-5");
+MODULE_ALIAS("md-level-4");