md: convert cpu notifier to return encapsulate errno value
[safe/jmp/linux-2.6] / drivers / md / raid5.c
index c3e5967..d2c0f94 100644 (file)
 #include <linux/async.h>
 #include <linux/seq_file.h>
 #include <linux/cpu.h>
+#include <linux/slab.h>
 #include "md.h"
 #include "raid5.h"
+#include "raid0.h"
 #include "bitmap.h"
 
 /*
@@ -156,13 +158,16 @@ static inline int raid6_next_disk(int disk, int raid_disks)
 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
                             int *count, int syndrome_disks)
 {
-       int slot;
+       int slot = *count;
 
+       if (sh->ddf_layout)
+               (*count)++;
        if (idx == sh->pd_idx)
                return syndrome_disks;
        if (idx == sh->qd_idx)
                return syndrome_disks + 1;
-       slot = (*count)++;
+       if (!sh->ddf_layout)
+               (*count)++;
        return slot;
 }
 
@@ -717,7 +722,7 @@ static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
        int i;
 
        for (i = 0; i < disks; i++)
-               srcs[i] = (void *)raid6_empty_zero_page;
+               srcs[i] = NULL;
 
        count = 0;
        i = d0_idx;
@@ -727,9 +732,8 @@ static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
                srcs[slot] = sh->dev[i].page;
                i = raid6_next_disk(i, disks);
        } while (i != d0_idx);
-       BUG_ON(count != syndrome_disks);
 
-       return count;
+       return syndrome_disks;
 }
 
 static struct dma_async_tx_descriptor *
@@ -814,7 +818,7 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
         * slot number conversion for 'faila' and 'failb'
         */
        for (i = 0; i < disks ; i++)
-               blocks[i] = (void *)raid6_empty_zero_page;
+               blocks[i] = NULL;
        count = 0;
        i = d0_idx;
        do {
@@ -828,7 +832,6 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
                        failb = slot;
                i = raid6_next_disk(i, disks);
        } while (i != d0_idx);
-       BUG_ON(count != syndrome_disks);
 
        BUG_ON(faila == failb);
        if (failb < faila)
@@ -845,7 +848,7 @@ ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
                        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
                                          ops_complete_compute, sh,
                                          to_addr_conv(sh, percpu));
-                       return async_gen_syndrome(blocks, 0, count+2,
+                       return async_gen_syndrome(blocks, 0, syndrome_disks+2,
                                                  STRIPE_SIZE, &submit);
                } else {
                        struct page *dest;
@@ -1139,7 +1142,7 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
                           &sh->ops.zero_sum_result, percpu->spare_page, &submit);
 }
 
-static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
+static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
 {
        int overlap_clear = 0, i, disks = sh->disks;
        struct dma_async_tx_descriptor *tx = NULL;
@@ -1204,22 +1207,55 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
        put_cpu();
 }
 
+#ifdef CONFIG_MULTICORE_RAID456
+static void async_run_ops(void *param, async_cookie_t cookie)
+{
+       struct stripe_head *sh = param;
+       unsigned long ops_request = sh->ops.request;
+
+       clear_bit_unlock(STRIPE_OPS_REQ_PENDING, &sh->state);
+       wake_up(&sh->ops.wait_for_ops);
+
+       __raid_run_ops(sh, ops_request);
+       release_stripe(sh);
+}
+
+static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
+{
+       /* since handle_stripe can be called outside of raid5d context
+        * we need to ensure sh->ops.request is de-staged before another
+        * request arrives
+        */
+       wait_event(sh->ops.wait_for_ops,
+                  !test_and_set_bit_lock(STRIPE_OPS_REQ_PENDING, &sh->state));
+       sh->ops.request = ops_request;
+
+       atomic_inc(&sh->count);
+       async_schedule(async_run_ops, sh);
+}
+#else
+#define raid_run_ops __raid_run_ops
+#endif
+
 static int grow_one_stripe(raid5_conf_t *conf)
 {
        struct stripe_head *sh;
+       int disks = max(conf->raid_disks, conf->previous_raid_disks);
        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));
+       memset(sh, 0, sizeof(*sh) + (disks-1)*sizeof(struct r5dev));
        sh->raid_conf = conf;
        spin_lock_init(&sh->lock);
+       #ifdef CONFIG_MULTICORE_RAID456
+       init_waitqueue_head(&sh->ops.wait_for_ops);
+       #endif
 
-       if (grow_buffers(sh, conf->raid_disks)) {
-               shrink_buffers(sh, conf->raid_disks);
+       if (grow_buffers(sh, disks)) {
+               shrink_buffers(sh, 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);
@@ -1231,7 +1267,7 @@ static int grow_one_stripe(raid5_conf_t *conf)
 static int grow_stripes(raid5_conf_t *conf, int num)
 {
        struct kmem_cache *sc;
-       int devs = conf->raid_disks;
+       int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
        sprintf(conf->cache_name[0],
                "raid%d-%s", conf->level, mdname(conf->mddev));
@@ -1329,6 +1365,9 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
 
                nsh->raid_conf = conf;
                spin_lock_init(&nsh->lock);
+               #ifdef CONFIG_MULTICORE_RAID456
+               init_waitqueue_head(&nsh->ops.wait_for_ops);
+               #endif
 
                list_add(&nsh->lru, &newstripes);
        }
@@ -1471,7 +1510,7 @@ static void raid5_end_read_request(struct bio * bi, int error)
                set_bit(R5_UPTODATE, &sh->dev[i].flags);
                if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
                        rdev = conf->disks[i].rdev;
-                       printk_rl(KERN_INFO "raid5:%s: read error corrected"
+                       printk_rl(KERN_INFO "md/raid:%s: read error corrected"
                                  " (%lu sectors at %llu on %s)\n",
                                  mdname(conf->mddev), STRIPE_SECTORS,
                                  (unsigned long long)(sh->sector
@@ -1489,9 +1528,9 @@ static void raid5_end_read_request(struct bio * bi, int error)
 
                clear_bit(R5_UPTODATE, &sh->dev[i].flags);
                atomic_inc(&rdev->read_errors);
-               if (conf->mddev->degraded)
+               if (conf->mddev->degraded >= conf->max_degraded)
                        printk_rl(KERN_WARNING
-                                 "raid5:%s: read error not correctable "
+                                 "md/raid:%s: read error not correctable "
                                  "(sector %llu on %s).\n",
                                  mdname(conf->mddev),
                                  (unsigned long long)(sh->sector
@@ -1500,7 +1539,7 @@ static void raid5_end_read_request(struct bio * bi, int error)
                else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
                        /* Oh, no!!! */
                        printk_rl(KERN_WARNING
-                                 "raid5:%s: read error NOT corrected!! "
+                                 "md/raid:%s: read error NOT corrected!! "
                                  "(sector %llu on %s).\n",
                                  mdname(conf->mddev),
                                  (unsigned long long)(sh->sector
@@ -1509,7 +1548,7 @@ static void raid5_end_read_request(struct bio * bi, int error)
                else if (atomic_read(&rdev->read_errors)
                         > conf->max_nr_stripes)
                        printk(KERN_WARNING
-                              "raid5:%s: Too many read errors, failing device %s.\n",
+                              "md/raid:%s: Too many read errors, failing device %s.\n",
                               mdname(conf->mddev), bdn);
                else
                        retry = 1;
@@ -1581,8 +1620,8 @@ static void raid5_build_block(struct stripe_head *sh, int i, int previous)
 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 {
        char b[BDEVNAME_SIZE];
-       raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
-       pr_debug("raid5: error called\n");
+       raid5_conf_t *conf = mddev->private;
+       pr_debug("raid456: error called\n");
 
        if (!test_bit(Faulty, &rdev->flags)) {
                set_bit(MD_CHANGE_DEVS, &mddev->flags);
@@ -1598,9 +1637,13 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
                }
                set_bit(Faulty, &rdev->flags);
                printk(KERN_ALERT
-                      "raid5: Disk failure on %s, disabling device.\n"
-                      "raid5: Operation continuing on %d devices.\n",
-                      bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
+                      "md/raid:%s: Disk failure on %s, disabling device.\n"
+                      KERN_ALERT
+                      "md/raid:%s: Operation continuing on %d devices.\n",
+                      mdname(mddev),
+                      bdevname(rdev->bdev, b),
+                      mdname(mddev),
+                      conf->raid_disks - mddev->degraded);
        }
 }
 
@@ -1612,8 +1655,8 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                                     int previous, int *dd_idx,
                                     struct stripe_head *sh)
 {
-       long stripe;
-       unsigned long chunk_number;
+       sector_t stripe, stripe2;
+       sector_t chunk_number;
        unsigned int chunk_offset;
        int pd_idx, qd_idx;
        int ddf_layout = 0;
@@ -1633,18 +1676,13 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
         */
        chunk_offset = sector_div(r_sector, sectors_per_chunk);
        chunk_number = r_sector;
-       BUG_ON(r_sector != chunk_number);
 
        /*
         * Compute the stripe number
         */
-       stripe = chunk_number / data_disks;
-
-       /*
-        * Compute the data disk and parity disk indexes inside the stripe
-        */
-       *dd_idx = chunk_number % data_disks;
-
+       stripe = chunk_number;
+       *dd_idx = sector_div(stripe, data_disks);
+       stripe2 = stripe;
        /*
         * Select the parity disk based on the user selected algorithm.
         */
@@ -1656,21 +1694,21 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
        case 5:
                switch (algorithm) {
                case ALGORITHM_LEFT_ASYMMETRIC:
-                       pd_idx = data_disks - stripe % raid_disks;
+                       pd_idx = data_disks - sector_div(stripe2, raid_disks);
                        if (*dd_idx >= pd_idx)
                                (*dd_idx)++;
                        break;
                case ALGORITHM_RIGHT_ASYMMETRIC:
-                       pd_idx = stripe % raid_disks;
+                       pd_idx = sector_div(stripe2, raid_disks);
                        if (*dd_idx >= pd_idx)
                                (*dd_idx)++;
                        break;
                case ALGORITHM_LEFT_SYMMETRIC:
-                       pd_idx = data_disks - stripe % raid_disks;
+                       pd_idx = data_disks - sector_div(stripe2, raid_disks);
                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
                        break;
                case ALGORITHM_RIGHT_SYMMETRIC:
-                       pd_idx = stripe % raid_disks;
+                       pd_idx = sector_div(stripe2, raid_disks);
                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
                        break;
                case ALGORITHM_PARITY_0:
@@ -1681,8 +1719,6 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                        pd_idx = data_disks;
                        break;
                default:
-                       printk(KERN_ERR "raid5: unsupported algorithm %d\n",
-                               algorithm);
                        BUG();
                }
                break;
@@ -1690,7 +1726,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
 
                switch (algorithm) {
                case ALGORITHM_LEFT_ASYMMETRIC:
-                       pd_idx = raid_disks - 1 - (stripe % raid_disks);
+                       pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
                        qd_idx = pd_idx + 1;
                        if (pd_idx == raid_disks-1) {
                                (*dd_idx)++;    /* Q D D D P */
@@ -1699,7 +1735,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                                (*dd_idx) += 2; /* D D P Q D */
                        break;
                case ALGORITHM_RIGHT_ASYMMETRIC:
-                       pd_idx = stripe % raid_disks;
+                       pd_idx = sector_div(stripe2, raid_disks);
                        qd_idx = pd_idx + 1;
                        if (pd_idx == raid_disks-1) {
                                (*dd_idx)++;    /* Q D D D P */
@@ -1708,12 +1744,12 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                                (*dd_idx) += 2; /* D D P Q D */
                        break;
                case ALGORITHM_LEFT_SYMMETRIC:
-                       pd_idx = raid_disks - 1 - (stripe % raid_disks);
+                       pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
                        qd_idx = (pd_idx + 1) % raid_disks;
                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
                        break;
                case ALGORITHM_RIGHT_SYMMETRIC:
-                       pd_idx = stripe % raid_disks;
+                       pd_idx = sector_div(stripe2, raid_disks);
                        qd_idx = (pd_idx + 1) % raid_disks;
                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
                        break;
@@ -1732,7 +1768,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                        /* Exactly the same as RIGHT_ASYMMETRIC, but or
                         * of blocks for computing Q is different.
                         */
-                       pd_idx = stripe % raid_disks;
+                       pd_idx = sector_div(stripe2, raid_disks);
                        qd_idx = pd_idx + 1;
                        if (pd_idx == raid_disks-1) {
                                (*dd_idx)++;    /* Q D D D P */
@@ -1747,7 +1783,8 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                         * D D D P Q  rather than
                         * Q D D D P
                         */
-                       pd_idx = raid_disks - 1 - ((stripe + 1) % raid_disks);
+                       stripe2 += 1;
+                       pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
                        qd_idx = pd_idx + 1;
                        if (pd_idx == raid_disks-1) {
                                (*dd_idx)++;    /* Q D D D P */
@@ -1759,7 +1796,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
 
                case ALGORITHM_ROTATING_N_CONTINUE:
                        /* Same as left_symmetric but Q is before P */
-                       pd_idx = raid_disks - 1 - (stripe % raid_disks);
+                       pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
                        qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
                        ddf_layout = 1;
@@ -1767,27 +1804,27 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
 
                case ALGORITHM_LEFT_ASYMMETRIC_6:
                        /* RAID5 left_asymmetric, with Q on last device */
-                       pd_idx = data_disks - stripe % (raid_disks-1);
+                       pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
                        if (*dd_idx >= pd_idx)
                                (*dd_idx)++;
                        qd_idx = raid_disks - 1;
                        break;
 
                case ALGORITHM_RIGHT_ASYMMETRIC_6:
-                       pd_idx = stripe % (raid_disks-1);
+                       pd_idx = sector_div(stripe2, raid_disks-1);
                        if (*dd_idx >= pd_idx)
                                (*dd_idx)++;
                        qd_idx = raid_disks - 1;
                        break;
 
                case ALGORITHM_LEFT_SYMMETRIC_6:
-                       pd_idx = data_disks - stripe % (raid_disks-1);
+                       pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
                        qd_idx = raid_disks - 1;
                        break;
 
                case ALGORITHM_RIGHT_SYMMETRIC_6:
-                       pd_idx = stripe % (raid_disks-1);
+                       pd_idx = sector_div(stripe2, raid_disks-1);
                        *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
                        qd_idx = raid_disks - 1;
                        break;
@@ -1798,10 +1835,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                        qd_idx = raid_disks - 1;
                        break;
 
-
                default:
-                       printk(KERN_CRIT "raid6: unsupported algorithm %d\n",
-                              algorithm);
                        BUG();
                }
                break;
@@ -1832,14 +1866,14 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                                 : conf->algorithm;
        sector_t stripe;
        int chunk_offset;
-       int chunk_number, dummy1, dd_idx = i;
+       sector_t chunk_number;
+       int dummy1, dd_idx = i;
        sector_t r_sector;
        struct stripe_head sh2;
 
 
        chunk_offset = sector_div(new_sector, sectors_per_chunk);
        stripe = new_sector;
-       BUG_ON(new_sector != stripe);
 
        if (i == sh->pd_idx)
                return 0;
@@ -1864,8 +1898,6 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                case ALGORITHM_PARITY_N:
                        break;
                default:
-                       printk(KERN_ERR "raid5: unsupported algorithm %d\n",
-                              algorithm);
                        BUG();
                }
                break;
@@ -1899,10 +1931,15 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                case ALGORITHM_PARITY_N:
                        break;
                case ALGORITHM_ROTATING_N_CONTINUE:
+                       /* Like left_symmetric, but P is before Q */
                        if (sh->pd_idx == 0)
                                i--;    /* P D D D Q */
-                       else if (i > sh->pd_idx)
-                               i -= 2; /* D D Q P D */
+                       else {
+                               /* D D Q P D */
+                               if (i < sh->pd_idx)
+                                       i += raid_disks;
+                               i -= (sh->pd_idx + 1);
+                       }
                        break;
                case ALGORITHM_LEFT_ASYMMETRIC_6:
                case ALGORITHM_RIGHT_ASYMMETRIC_6:
@@ -1919,21 +1956,20 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
                        i -= 1;
                        break;
                default:
-                       printk(KERN_CRIT "raid6: unsupported algorithm %d\n",
-                              algorithm);
                        BUG();
                }
                break;
        }
 
        chunk_number = stripe * data_disks + i;
-       r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
+       r_sector = chunk_number * sectors_per_chunk + chunk_offset;
 
        check = raid5_compute_sector(conf, r_sector,
                                     previous, &dummy1, &sh2);
        if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
                || sh2.qd_idx != sh->qd_idx) {
-               printk(KERN_ERR "compute_blocknr: map not correct\n");
+               printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
+                      mdname(conf->mddev));
                return 0;
        }
        return r_sector;
@@ -2905,6 +2941,7 @@ static void handle_stripe5(struct stripe_head *sh)
        struct r5dev *dev;
        mdk_rdev_t *blocked_rdev = NULL;
        int prexor;
+       int dec_preread_active = 0;
 
        memset(&s, 0, sizeof(s));
        pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
@@ -3054,12 +3091,8 @@ static void handle_stripe5(struct stripe_head *sh)
                                        set_bit(STRIPE_INSYNC, &sh->state);
                        }
                }
-               if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-                       atomic_dec(&conf->preread_active_stripes);
-                       if (atomic_read(&conf->preread_active_stripes) <
-                               IO_THRESHOLD)
-                               md_wakeup_thread(conf->mddev->thread);
-               }
+               if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+                       dec_preread_active = 1;
        }
 
        /* Now to consider new write requests and what else, if anything
@@ -3166,6 +3199,16 @@ static void handle_stripe5(struct stripe_head *sh)
 
        ops_run_io(sh, &s);
 
+       if (dec_preread_active) {
+               /* We delay this until after ops_run_io so that if make_request
+                * is waiting on a barrier, it won't continue until the writes
+                * have actually been submitted.
+                */
+               atomic_dec(&conf->preread_active_stripes);
+               if (atomic_read(&conf->preread_active_stripes) <
+                   IO_THRESHOLD)
+                       md_wakeup_thread(conf->mddev->thread);
+       }
        return_io(return_bi);
 }
 
@@ -3179,6 +3222,7 @@ static void handle_stripe6(struct stripe_head *sh)
        struct r6_state r6s;
        struct r5dev *dev, *pdev, *qdev;
        mdk_rdev_t *blocked_rdev = NULL;
+       int dec_preread_active = 0;
 
        pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
                "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
@@ -3316,7 +3360,6 @@ static void handle_stripe6(struct stripe_head *sh)
         * completed
         */
        if (sh->reconstruct_state == reconstruct_state_drain_result) {
-               int qd_idx = sh->qd_idx;
 
                sh->reconstruct_state = reconstruct_state_idle;
                /* All the 'written' buffers and the parity blocks are ready to
@@ -3338,12 +3381,8 @@ static void handle_stripe6(struct stripe_head *sh)
                                        set_bit(STRIPE_INSYNC, &sh->state);
                        }
                }
-               if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-                       atomic_dec(&conf->preread_active_stripes);
-                       if (atomic_read(&conf->preread_active_stripes) <
-                               IO_THRESHOLD)
-                               md_wakeup_thread(conf->mddev->thread);
-               }
+               if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+                       dec_preread_active = 1;
        }
 
        /* Now to consider new write requests and what else, if anything
@@ -3452,6 +3491,18 @@ static void handle_stripe6(struct stripe_head *sh)
 
        ops_run_io(sh, &s);
 
+
+       if (dec_preread_active) {
+               /* We delay this until after ops_run_io so that if make_request
+                * is waiting on a barrier, it won't continue until the writes
+                * have actually been submitted.
+                */
+               atomic_dec(&conf->preread_active_stripes);
+               if (atomic_read(&conf->preread_active_stripes) <
+                   IO_THRESHOLD)
+                       md_wakeup_thread(conf->mddev->thread);
+       }
+
        return_io(return_bi);
 }
 
@@ -3498,9 +3549,10 @@ static void unplug_slaves(mddev_t *mddev)
 {
        raid5_conf_t *conf = mddev->private;
        int i;
+       int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
        rcu_read_lock();
-       for (i = 0; i < conf->raid_disks; i++) {
+       for (i = 0; i < devs; i++) {
                mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
                if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
                        struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
@@ -3654,10 +3706,10 @@ static void raid5_align_endio(struct bio *bi, int error)
 
        bio_put(bi);
 
-       mddev = raid_bi->bi_bdev->bd_disk->queue->queuedata;
-       conf = mddev->private;
        rdev = (void*)raid_bi->bi_next;
        raid_bi->bi_next = NULL;
+       mddev = rdev->mddev;
+       conf = mddev->private;
 
        rdev_dec_pending(rdev, conf->mddev);
 
@@ -3681,7 +3733,7 @@ static int bio_fits_rdev(struct bio *bi)
        if ((bi->bi_size>>9) > queue_max_sectors(q))
                return 0;
        blk_recount_segments(q, bi);
-       if (bi->bi_phys_segments > queue_max_phys_segments(q))
+       if (bi->bi_phys_segments > queue_max_segments(q))
                return 0;
 
        if (q->merge_bvec_fn)
@@ -3694,11 +3746,10 @@ static int bio_fits_rdev(struct bio *bi)
 }
 
 
-static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
+static int chunk_aligned_read(mddev_t *mddev, struct bio * raid_bio)
 {
-       mddev_t *mddev = q->queuedata;
        raid5_conf_t *conf = mddev->private;
-       unsigned int dd_idx;
+       int dd_idx;
        struct bio* align_bi;
        mdk_rdev_t *rdev;
 
@@ -3811,33 +3862,32 @@ static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
        return sh;
 }
 
-static int make_request(struct request_queue *q, struct bio * bi)
+static int make_request(mddev_t *mddev, struct bio * bi)
 {
-       mddev_t *mddev = q->queuedata;
        raid5_conf_t *conf = mddev->private;
        int dd_idx;
        sector_t new_sector;
        sector_t logical_sector, last_sector;
        struct stripe_head *sh;
        const int rw = bio_data_dir(bi);
-       int cpu, remaining;
+       int remaining;
 
        if (unlikely(bio_rw_flagged(bi, BIO_RW_BARRIER))) {
-               bio_endio(bi, -EOPNOTSUPP);
+               /* Drain all pending writes.  We only really need
+                * to ensure they have been submitted, but this is
+                * easier.
+                */
+               mddev->pers->quiesce(mddev, 1);
+               mddev->pers->quiesce(mddev, 0);
+               md_barrier_request(mddev, bi);
                return 0;
        }
 
        md_write_start(mddev, bi);
 
-       cpu = part_stat_lock();
-       part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
-       part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
-                     bio_sectors(bi));
-       part_stat_unlock();
-
        if (rw == READ &&
             mddev->reshape_position == MaxSector &&
-            chunk_aligned_read(q,bi))
+            chunk_aligned_read(mddev,bi))
                return 0;
 
        logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
@@ -3885,7 +3935,7 @@ static int make_request(struct request_queue *q, struct bio * bi)
                new_sector = raid5_compute_sector(conf, logical_sector,
                                                  previous,
                                                  &dd_idx, NULL);
-               pr_debug("raid5: make_request, sector %llu logical %llu\n",
+               pr_debug("raid456: make_request, sector %llu logical %llu\n",
                        (unsigned long long)new_sector, 
                        (unsigned long long)logical_sector);
 
@@ -3947,6 +3997,9 @@ static int make_request(struct request_queue *q, struct bio * bi)
                        finish_wait(&conf->wait_for_overlap, &w);
                        set_bit(STRIPE_HANDLE, &sh->state);
                        clear_bit(STRIPE_DELAYED, &sh->state);
+                       if (mddev->barrier && 
+                           !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+                               atomic_inc(&conf->preread_active_stripes);
                        release_stripe(sh);
                } else {
                        /* cannot get stripe for read-ahead, just give-up */
@@ -3966,6 +4019,14 @@ static int make_request(struct request_queue *q, struct bio * bi)
 
                bio_endio(bi, 0);
        }
+
+       if (mddev->barrier) {
+               /* We need to wait for the stripes to all be handled.
+                * So: wait for preread_active_stripes to drop to 0.
+                */
+               wait_event(mddev->thread->wqueue,
+                          atomic_read(&conf->preread_active_stripes) == 0);
+       }
        return 0;
 }
 
@@ -3982,7 +4043,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
         * As the reads complete, handle_stripe will copy the data
         * into the destination stripe and release that stripe.
         */
-       raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
+       raid5_conf_t *conf = mddev->private;
        struct stripe_head *sh;
        sector_t first_sector, last_sector;
        int raid_disks = conf->previous_raid_disks;
@@ -4006,6 +4067,8 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
                        sector_nr = conf->reshape_progress;
                sector_div(sector_nr, new_data_disks);
                if (sector_nr) {
+                       mddev->curr_resync_completed = sector_nr;
+                       sysfs_notify(&mddev->kobj, NULL, "sync_completed");
                        *skipped = 1;
                        return sector_nr;
                }
@@ -4189,7 +4252,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
 /* FIXME go_faster isn't used */
 static inline 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;
+       raid5_conf_t *conf = mddev->private;
        struct stripe_head *sh;
        sector_t max_sector = mddev->dev_sectors;
        int sync_blocks;
@@ -4342,37 +4405,6 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
        return handled;
 }
 
-#ifdef CONFIG_MULTICORE_RAID456
-static void __process_stripe(void *param, async_cookie_t cookie)
-{
-       struct stripe_head *sh = param;
-
-       handle_stripe(sh);
-       release_stripe(sh);
-}
-
-static void process_stripe(struct stripe_head *sh, struct list_head *domain)
-{
-       async_schedule_domain(__process_stripe, sh, domain);
-}
-
-static void synchronize_stripe_processing(struct list_head *domain)
-{
-       async_synchronize_full_domain(domain);
-}
-#else
-static void process_stripe(struct stripe_head *sh, struct list_head *domain)
-{
-       handle_stripe(sh);
-       release_stripe(sh);
-       cond_resched();
-}
-
-static void synchronize_stripe_processing(struct list_head *domain)
-{
-}
-#endif
-
 
 /*
  * This is our raid5 kernel thread.
@@ -4386,7 +4418,6 @@ static void raid5d(mddev_t *mddev)
        struct stripe_head *sh;
        raid5_conf_t *conf = mddev->private;
        int handled;
-       LIST_HEAD(raid_domain);
 
        pr_debug("+++ raid5d active\n");
 
@@ -4423,7 +4454,9 @@ static void raid5d(mddev_t *mddev)
                spin_unlock_irq(&conf->device_lock);
                
                handled++;
-               process_stripe(sh, &raid_domain);
+               handle_stripe(sh);
+               release_stripe(sh);
+               cond_resched();
 
                spin_lock_irq(&conf->device_lock);
        }
@@ -4431,7 +4464,6 @@ static void raid5d(mddev_t *mddev)
 
        spin_unlock_irq(&conf->device_lock);
 
-       synchronize_stripe_processing(&raid_domain);
        async_tx_issue_pending_all();
        unplug_slaves(mddev);
 
@@ -4551,13 +4583,9 @@ raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 
        if (!sectors)
                sectors = mddev->dev_sectors;
-       if (!raid_disks) {
+       if (!raid_disks)
                /* size is defined by the smallest of previous and new size */
-               if (conf->raid_disks < conf->previous_raid_disks)
-                       raid_disks = conf->raid_disks;
-               else
-                       raid_disks = conf->previous_raid_disks;
-       }
+               raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
 
        sectors &= ~((sector_t)mddev->chunk_sectors - 1);
        sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
@@ -4617,7 +4645,7 @@ static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
                        kfree(percpu->scribble);
                        pr_err("%s: failed memory allocation for cpu%ld\n",
                               __func__, cpu);
-                       return NOTIFY_BAD;
+                       return notifier_from_errno(-ENOMEM);
                }
                break;
        case CPU_DEAD:
@@ -4638,7 +4666,7 @@ static int raid5_alloc_percpu(raid5_conf_t *conf)
 {
        unsigned long cpu;
        struct page *spare_page;
-       struct raid5_percpu *allcpus;
+       struct raid5_percpu __percpu *allcpus;
        void *scribble;
        int err;
 
@@ -4658,7 +4686,7 @@ static int raid5_alloc_percpu(raid5_conf_t *conf)
                        }
                        per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
                }
-               scribble = kmalloc(scribble_len(conf->raid_disks), GFP_KERNEL);
+               scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
                if (!scribble) {
                        err = -ENOMEM;
                        break;
@@ -4679,14 +4707,14 @@ static int raid5_alloc_percpu(raid5_conf_t *conf)
 static raid5_conf_t *setup_conf(mddev_t *mddev)
 {
        raid5_conf_t *conf;
-       int raid_disk, memory;
+       int raid_disk, memory, max_disks;
        mdk_rdev_t *rdev;
        struct disk_info *disk;
 
        if (mddev->new_level != 5
            && mddev->new_level != 4
            && mddev->new_level != 6) {
-               printk(KERN_ERR "raid5: %s: raid level not set to 4/5/6 (%d)\n",
+               printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
                       mdname(mddev), mddev->new_level);
                return ERR_PTR(-EIO);
        }
@@ -4694,12 +4722,12 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
             && !algorithm_valid_raid5(mddev->new_layout)) ||
            (mddev->new_level == 6
             && !algorithm_valid_raid6(mddev->new_layout))) {
-               printk(KERN_ERR "raid5: %s: layout %d not supported\n",
+               printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
                       mdname(mddev), mddev->new_layout);
                return ERR_PTR(-EIO);
        }
        if (mddev->new_level == 6 && mddev->raid_disks < 4) {
-               printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
+               printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
                       mdname(mddev), mddev->raid_disks);
                return ERR_PTR(-EINVAL);
        }
@@ -4707,8 +4735,8 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        if (!mddev->new_chunk_sectors ||
            (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
            !is_power_of_2(mddev->new_chunk_sectors)) {
-               printk(KERN_ERR "raid5: invalid chunk size %d for %s\n",
-                      mddev->new_chunk_sectors << 9, mdname(mddev));
+               printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
+                      mdname(mddev), mddev->new_chunk_sectors << 9);
                return ERR_PTR(-EINVAL);
        }
 
@@ -4729,13 +4757,14 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        conf->bypass_threshold = BYPASS_THRESHOLD;
 
        conf->raid_disks = mddev->raid_disks;
-       conf->scribble_len = scribble_len(conf->raid_disks);
        if (mddev->reshape_position == MaxSector)
                conf->previous_raid_disks = mddev->raid_disks;
        else
                conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
+       max_disks = max(conf->raid_disks, conf->previous_raid_disks);
+       conf->scribble_len = scribble_len(max_disks);
 
-       conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
+       conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
                              GFP_KERNEL);
        if (!conf->disks)
                goto abort;
@@ -4749,11 +4778,11 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        if (raid5_alloc_percpu(conf) != 0)
                goto abort;
 
-       pr_debug("raid5: run(%s) called.\n", mdname(mddev));
+       pr_debug("raid456: run(%s) called.\n", mdname(mddev));
 
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                raid_disk = rdev->raid_disk;
-               if (raid_disk >= conf->raid_disks
+               if (raid_disk >= max_disks
                    || raid_disk < 0)
                        continue;
                disk = conf->disks + raid_disk;
@@ -4762,9 +4791,9 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 
                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),
-                               raid_disk);
+                       printk(KERN_INFO "md/raid:%s: device %s operational as raid"
+                              " disk %d\n",
+                              mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
                } else
                        /* Cannot rely on bitmap to complete recovery */
                        conf->fullsync = 1;
@@ -4785,19 +4814,20 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        }
 
        memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
-                conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
+                max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
        if (grow_stripes(conf, conf->max_nr_stripes)) {
                printk(KERN_ERR
-                       "raid5: couldn't allocate %dkB for buffers\n", memory);
+                      "md/raid:%s: couldn't allocate %dkB for buffers\n",
+                      mdname(mddev), memory);
                goto abort;
        } else
-               printk(KERN_INFO "raid5: allocated %dkB for %s\n",
-                       memory, mdname(mddev));
+               printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
+                      mdname(mddev), memory);
 
        conf->thread = md_register_thread(raid5d, mddev, NULL);
        if (!conf->thread) {
                printk(KERN_ERR
-                      "raid5: couldn't allocate thread for %s\n",
+                      "md/raid:%s: couldn't allocate thread.\n",
                       mdname(mddev));
                goto abort;
        }
@@ -4812,14 +4842,43 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
                return ERR_PTR(-ENOMEM);
 }
 
+
+static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
+{
+       switch (algo) {
+       case ALGORITHM_PARITY_0:
+               if (raid_disk < max_degraded)
+                       return 1;
+               break;
+       case ALGORITHM_PARITY_N:
+               if (raid_disk >= raid_disks - max_degraded)
+                       return 1;
+               break;
+       case ALGORITHM_PARITY_0_6:
+               if (raid_disk == 0 || 
+                   raid_disk == raid_disks - 1)
+                       return 1;
+               break;
+       case ALGORITHM_LEFT_ASYMMETRIC_6:
+       case ALGORITHM_RIGHT_ASYMMETRIC_6:
+       case ALGORITHM_LEFT_SYMMETRIC_6:
+       case ALGORITHM_RIGHT_SYMMETRIC_6:
+               if (raid_disk == raid_disks - 1)
+                       return 1;
+       }
+       return 0;
+}
+
 static int run(mddev_t *mddev)
 {
        raid5_conf_t *conf;
        int working_disks = 0, chunk_size;
+       int dirty_parity_disks = 0;
        mdk_rdev_t *rdev;
+       sector_t reshape_offset = 0;
 
        if (mddev->recovery_cp != MaxSector)
-               printk(KERN_NOTICE "raid5: %s is not clean"
+               printk(KERN_NOTICE "md/raid:%s: not clean"
                       " -- starting background reconstruction\n",
                       mdname(mddev));
        if (mddev->reshape_position != MaxSector) {
@@ -4833,7 +4892,7 @@ static int run(mddev_t *mddev)
                int max_degraded = (mddev->level == 6 ? 2 : 1);
 
                if (mddev->new_level != mddev->level) {
-                       printk(KERN_ERR "raid5: %s: unsupported reshape "
+                       printk(KERN_ERR "md/raid:%s: unsupported reshape "
                               "required - aborting.\n",
                               mdname(mddev));
                        return -EINVAL;
@@ -4846,10 +4905,11 @@ static int run(mddev_t *mddev)
                here_new = mddev->reshape_position;
                if (sector_div(here_new, mddev->new_chunk_sectors *
                               (mddev->raid_disks - max_degraded))) {
-                       printk(KERN_ERR "raid5: reshape_position not "
-                              "on a stripe boundary\n");
+                       printk(KERN_ERR "md/raid:%s: reshape_position not "
+                              "on a stripe boundary\n", mdname(mddev));
                        return -EINVAL;
                }
+               reshape_offset = here_new * mddev->new_chunk_sectors;
                /* here_new is the stripe we will write to */
                here_old = mddev->reshape_position;
                sector_div(here_old, mddev->chunk_sectors *
@@ -4867,8 +4927,9 @@ static int run(mddev_t *mddev)
                        if ((here_new * mddev->new_chunk_sectors != 
                             here_old * mddev->chunk_sectors) ||
                            mddev->ro == 0) {
-                               printk(KERN_ERR "raid5: in-place reshape must be started"
-                                      " in read-only mode - aborting\n");
+                               printk(KERN_ERR "md/raid:%s: in-place reshape must be started"
+                                      " in read-only mode - aborting\n",
+                                      mdname(mddev));
                                return -EINVAL;
                        }
                } else if (mddev->delta_disks < 0
@@ -4877,11 +4938,13 @@ static int run(mddev_t *mddev)
                    : (here_new * mddev->new_chunk_sectors >=
                       here_old * mddev->chunk_sectors)) {
                        /* Reading from the same stripe as writing to - bad */
-                       printk(KERN_ERR "raid5: reshape_position too early for "
-                              "auto-recovery - aborting.\n");
+                       printk(KERN_ERR "md/raid:%s: reshape_position too early for "
+                              "auto-recovery - aborting.\n",
+                              mdname(mddev));
                        return -EINVAL;
                }
-               printk(KERN_INFO "raid5: reshape will continue\n");
+               printk(KERN_INFO "md/raid:%s: reshape will continue\n",
+                      mdname(mddev));
                /* OK, we should be able to continue; */
        } else {
                BUG_ON(mddev->level != mddev->new_level);
@@ -4905,15 +4968,45 @@ static int run(mddev_t *mddev)
        /*
         * 0 for a fully functional array, 1 or 2 for a degraded array.
         */
-       list_for_each_entry(rdev, &mddev->disks, same_set)
-               if (rdev->raid_disk >= 0 &&
-                   test_bit(In_sync, &rdev->flags))
+       list_for_each_entry(rdev, &mddev->disks, same_set) {
+               if (rdev->raid_disk < 0)
+                       continue;
+               if (test_bit(In_sync, &rdev->flags))
                        working_disks++;
+               /* This disc is not fully in-sync.  However if it
+                * just stored parity (beyond the recovery_offset),
+                * when we don't need to be concerned about the
+                * array being dirty.
+                * When reshape goes 'backwards', we never have
+                * partially completed devices, so we only need
+                * to worry about reshape going forwards.
+                */
+               /* Hack because v0.91 doesn't store recovery_offset properly. */
+               if (mddev->major_version == 0 &&
+                   mddev->minor_version > 90)
+                       rdev->recovery_offset = reshape_offset;
+                       
+               if (rdev->recovery_offset < reshape_offset) {
+                       /* We need to check old and new layout */
+                       if (!only_parity(rdev->raid_disk,
+                                        conf->algorithm,
+                                        conf->raid_disks,
+                                        conf->max_degraded))
+                               continue;
+               }
+               if (!only_parity(rdev->raid_disk,
+                                conf->prev_algo,
+                                conf->previous_raid_disks,
+                                conf->max_degraded))
+                       continue;
+               dirty_parity_disks++;
+       }
 
-       mddev->degraded = conf->raid_disks - working_disks;
+       mddev->degraded = (max(conf->raid_disks, conf->previous_raid_disks)
+                          - working_disks);
 
        if (mddev->degraded > conf->max_degraded) {
-               printk(KERN_ERR "raid5: not enough operational devices for %s"
+               printk(KERN_ERR "md/raid:%s: not enough operational devices"
                        " (%d/%d failed)\n",
                        mdname(mddev), mddev->degraded, conf->raid_disks);
                goto abort;
@@ -4923,36 +5016,36 @@ static int run(mddev_t *mddev)
        mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
        mddev->resync_max_sectors = mddev->dev_sectors;
 
-       if (mddev->degraded > 0 &&
+       if (mddev->degraded > dirty_parity_disks &&
            mddev->recovery_cp != MaxSector) {
                if (mddev->ok_start_degraded)
                        printk(KERN_WARNING
-                              "raid5: starting dirty degraded array: %s"
-                              "- data corruption possible.\n",
+                              "md/raid:%s: starting dirty degraded array"
+                              " - data corruption possible.\n",
                               mdname(mddev));
                else {
                        printk(KERN_ERR
-                              "raid5: cannot start dirty degraded array for %s\n",
+                              "md/raid:%s: cannot start dirty degraded array.\n",
                               mdname(mddev));
                        goto abort;
                }
        }
 
        if (mddev->degraded == 0)
-               printk("raid5: raid level %d set %s active with %d out of %d"
-                      " devices, algorithm %d\n", conf->level, mdname(mddev),
+               printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
+                      " devices, algorithm %d\n", mdname(mddev), conf->level,
                       mddev->raid_disks-mddev->degraded, mddev->raid_disks,
                       mddev->new_layout);
        else
-               printk(KERN_ALERT "raid5: raid level %d set %s active with %d"
-                       " out of %d devices, algorithm %d\n", conf->level,
-                       mdname(mddev), mddev->raid_disks - mddev->degraded,
-                       mddev->raid_disks, mddev->new_layout);
+               printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
+                      " out of %d devices, algorithm %d\n",
+                      mdname(mddev), conf->level,
+                      mddev->raid_disks - mddev->degraded,
+                      mddev->raid_disks, mddev->new_layout);
 
        print_raid5_conf(conf);
 
        if (conf->reshape_progress != MaxSector) {
-               printk("...ok start reshape thread\n");
                conf->reshape_safe = conf->reshape_progress;
                atomic_set(&conf->reshape_stripes, 0);
                clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
@@ -4975,9 +5068,11 @@ static int run(mddev_t *mddev)
        }
 
        /* Ok, everything is just fine now */
-       if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
+       if (mddev->to_remove == &raid5_attrs_group)
+               mddev->to_remove = NULL;
+       else if (sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
                printk(KERN_WARNING
-                      "raid5: failed to create sysfs attributes for %s\n",
+                      "md/raid:%s: failed to create sysfs attributes.\n",
                       mdname(mddev));
 
        mddev->queue->queue_lock = &conf->device_lock;
@@ -5007,23 +5102,21 @@ abort:
                free_conf(conf);
        }
        mddev->private = NULL;
-       printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev));
+       printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
        return -EIO;
 }
 
-
-
 static int stop(mddev_t *mddev)
 {
-       raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
+       raid5_conf_t *conf = mddev->private;
 
        md_unregister_thread(mddev->thread);
        mddev->thread = NULL;
        mddev->queue->backing_dev_info.congested_fn = NULL;
        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
-       sysfs_remove_group(&mddev->kobj, &raid5_attrs_group);
        free_conf(conf);
        mddev->private = NULL;
+       mddev->to_remove = &raid5_attrs_group;
        return 0;
 }
 
@@ -5064,7 +5157,7 @@ static void printall(struct seq_file *seq, raid5_conf_t *conf)
 
 static void status(struct seq_file *seq, mddev_t *mddev)
 {
-       raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
+       raid5_conf_t *conf = mddev->private;
        int i;
 
        seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
@@ -5086,21 +5179,22 @@ static void print_raid5_conf (raid5_conf_t *conf)
        int i;
        struct disk_info *tmp;
 
-       printk("RAID5 conf printout:\n");
+       printk(KERN_DEBUG "RAID conf printout:\n");
        if (!conf) {
                printk("(conf==NULL)\n");
                return;
        }
-       printk(" --- rd:%d wd:%d\n", conf->raid_disks,
-                conf->raid_disks - conf->mddev->degraded);
+       printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
+              conf->raid_disks,
+              conf->raid_disks - conf->mddev->degraded);
 
        for (i = 0; i < conf->raid_disks; i++) {
                char b[BDEVNAME_SIZE];
                tmp = conf->disks + i;
                if (tmp->rdev)
-               printk(" disk %d, o:%d, dev:%s\n",
-                       i, !test_bit(Faulty, &tmp->rdev->flags),
-                       bdevname(tmp->rdev->bdev,b));
+                       printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
+                              i, !test_bit(Faulty, &tmp->rdev->flags),
+                              bdevname(tmp->rdev->bdev, b));
        }
 }
 
@@ -5223,7 +5317,6 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
            raid5_size(mddev, sectors, mddev->raid_disks))
                return -EINVAL;
        set_capacity(mddev->gendisk, mddev->array_sectors);
-       mddev->changed = 1;
        revalidate_disk(mddev->gendisk);
        if (sectors > mddev->dev_sectors && mddev->recovery_cp == MaxSector) {
                mddev->recovery_cp = mddev->dev_sectors;
@@ -5249,7 +5342,8 @@ static int check_stripe_cache(mddev_t *mddev)
            > conf->max_nr_stripes ||
            ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
            > conf->max_nr_stripes) {
-               printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
+               printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
+                      mdname(mddev),
                       ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
                        / STRIPE_SIZE)*4);
                return 0;
@@ -5320,7 +5414,7 @@ static int raid5_start_reshape(mddev_t *mddev)
         */
        if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
            < mddev->array_sectors) {
-               printk(KERN_ERR "md%s: array size must be reduced "
+               printk(KERN_ERR "md/raid:%s: array size must be reduced "
                       "before number of disks\n", mdname(mddev));
                return -EINVAL;
        }
@@ -5349,23 +5443,28 @@ static int raid5_start_reshape(mddev_t *mddev)
                    !test_bit(Faulty, &rdev->flags)) {
                        if (raid5_add_disk(mddev, rdev) == 0) {
                                char nm[20];
-                               set_bit(In_sync, &rdev->flags);
-                               added_devices++;
-                               rdev->recovery_offset = 0;
+                               if (rdev->raid_disk >= conf->previous_raid_disks) {
+                                       set_bit(In_sync, &rdev->flags);
+                                       added_devices++;
+                               } else
+                                       rdev->recovery_offset = 0;
                                sprintf(nm, "rd%d", rdev->raid_disk);
                                if (sysfs_create_link(&mddev->kobj,
                                                      &rdev->kobj, nm))
                                        printk(KERN_WARNING
-                                              "raid5: failed to create "
-                                              " link %s for %s\n",
-                                              nm, mdname(mddev));
+                                              "md/raid:%s: failed to create "
+                                              " link %s\n",
+                                              mdname(mddev), nm);
                        } else
                                break;
                }
 
+       /* When a reshape changes the number of devices, ->degraded
+        * is measured against the large of the pre and post number of
+        * devices.*/
        if (mddev->delta_disks > 0) {
                spin_lock_irqsave(&conf->device_lock, flags);
-               mddev->degraded = (conf->raid_disks - conf->previous_raid_disks)
+               mddev->degraded += (conf->raid_disks - conf->previous_raid_disks)
                        - added_devices;
                spin_unlock_irqrestore(&conf->device_lock, flags);
        }
@@ -5432,7 +5531,6 @@ static void raid5_finish_reshape(mddev_t *mddev)
                if (mddev->delta_disks > 0) {
                        md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
                        set_capacity(mddev->gendisk, mddev->array_sectors);
-                       mddev->changed = 1;
                        revalidate_disk(mddev->gendisk);
                } else {
                        int d;
@@ -5497,6 +5595,29 @@ static void raid5_quiesce(mddev_t *mddev, int state)
 }
 
 
+static void *raid45_takeover_raid0(mddev_t *mddev, int level)
+{
+       struct raid0_private_data *raid0_priv = mddev->private;
+
+       /* for raid0 takeover only one zone is supported */
+       if (raid0_priv->nr_strip_zones > 1) {
+               printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
+                      mdname(mddev));
+               return ERR_PTR(-EINVAL);
+       }
+
+       mddev->new_level = level;
+       mddev->new_layout = ALGORITHM_PARITY_N;
+       mddev->new_chunk_sectors = mddev->chunk_sectors;
+       mddev->raid_disks += 1;
+       mddev->delta_disks = 1;
+       /* make sure it will be not marked as dirty */
+       mddev->recovery_cp = MaxSector;
+
+       return setup_conf(mddev);
+}
+
+
 static void *raid5_takeover_raid1(mddev_t *mddev)
 {
        int chunksect;
@@ -5621,12 +5742,13 @@ static int raid6_check_reshape(mddev_t *mddev)
 static void *raid5_takeover(mddev_t *mddev)
 {
        /* raid5 can take over:
-        *  raid0 - if all devices are the same - make it a raid4 layout
+        *  raid0 - if there is only one strip zone - make it a raid4 layout
         *  raid1 - if there are two drives.  We need to know the chunk size
         *  raid4 - trivial - just use a raid4 layout.
         *  raid6 - Providing it is a *_6 layout
         */
-
+       if (mddev->level == 0)
+               return raid45_takeover_raid0(mddev, 5);
        if (mddev->level == 1)
                return raid5_takeover_raid1(mddev);
        if (mddev->level == 4) {
@@ -5640,6 +5762,22 @@ static void *raid5_takeover(mddev_t *mddev)
        return ERR_PTR(-EINVAL);
 }
 
+static void *raid4_takeover(mddev_t *mddev)
+{
+       /* raid4 can take over:
+        *  raid0 - if there is only one strip zone
+        *  raid5 - if layout is right
+        */
+       if (mddev->level == 0)
+               return raid45_takeover_raid0(mddev, 4);
+       if (mddev->level == 5 &&
+           mddev->layout == ALGORITHM_PARITY_N) {
+               mddev->new_layout = 0;
+               mddev->new_level = 4;
+               return setup_conf(mddev);
+       }
+       return ERR_PTR(-EINVAL);
+}
 
 static struct mdk_personality raid5_personality;
 
@@ -5755,6 +5893,7 @@ static struct mdk_personality raid4_personality =
        .start_reshape  = raid5_start_reshape,
        .finish_reshape = raid5_finish_reshape,
        .quiesce        = raid5_quiesce,
+       .takeover       = raid4_takeover,
 };
 
 static int __init raid5_init(void)
@@ -5775,6 +5914,7 @@ static void raid5_exit(void)
 module_init(raid5_init);
 module_exit(raid5_exit);
 MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
 MODULE_ALIAS("md-personality-4"); /* RAID5 */
 MODULE_ALIAS("md-raid5");
 MODULE_ALIAS("md-raid4");