2 files changed, 112 insertions, 14 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index e64c971038d1..b182f86a19dd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -944,6 +944,14 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                             desc->raid_disk < mddev->raid_disks */) {
                         set_bit(In_sync, &rdev->flags);
                         rdev->raid_disk = desc->raid_disk;
+                } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
+                        /* active but not in sync implies recovery up to
+                         * reshape position.  We don't know exactly where
+                         * that is, so set to zero for now */
+                        if (mddev->minor_version >= 91) {
+                                rdev->recovery_offset = 0;
+                                rdev->raid_disk = desc->raid_disk;
+                        }
                 }
                 if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
                         set_bit(WriteMostly, &rdev->flags);
@@ -1032,8 +1040,19 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         list_for_each_entry(rdev2, &mddev->disks, same_set) {
                 mdp_disk_t *d;
                 int desc_nr;
-                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
-                    && !test_bit(Faulty, &rdev2->flags))
+                int is_active = test_bit(In_sync, &rdev2->flags);
+
+                if (rdev2->raid_disk >= 0 &&
+                    sb->minor_version >= 91)
+                        /* we have nowhere to store the recovery_offset,
+                         * but if it is not below the reshape_position,
+                         * we can piggy-back on that.
+                         */
+                        is_active = 1;
+                if (rdev2->raid_disk < 0 ||
+                    test_bit(Faulty, &rdev2->flags))
+                        is_active = 0;
+                if (is_active)
                         desc_nr = rdev2->raid_disk;
                 else
                         desc_nr = next_spare++;
@@ -1043,16 +1062,16 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
                 d->number = rdev2->desc_nr;
                 d->major = MAJOR(rdev2->bdev->bd_dev);
                 d->minor = MINOR(rdev2->bdev->bd_dev);
-                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
-                    && !test_bit(Faulty, &rdev2->flags))
+                if (is_active)
                         d->raid_disk = rdev2->raid_disk;
                 else
                         d->raid_disk = rdev2->desc_nr; /* compatibility */
                 if (test_bit(Faulty, &rdev2->flags))
                         d->state = (1<<MD_DISK_FAULTY);
-                else if (test_bit(In_sync, &rdev2->flags)) {
+                else if (is_active) {
                         d->state = (1<<MD_DISK_ACTIVE);
-                        d->state |= (1<<MD_DISK_SYNC);
+                        if (test_bit(In_sync, &rdev2->flags))
+                                d->state |= (1<<MD_DISK_SYNC);
                         active++;
                         working++;
                 } else {
@@ -1382,8 +1401,6 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 
         if (rdev->raid_disk >= 0 &&
             !test_bit(In_sync, &rdev->flags)) {
-                if (mddev->curr_resync_completed > rdev->recovery_offset)
-                        rdev->recovery_offset = mddev->curr_resync_completed;
                 if (rdev->recovery_offset > 0) {
                         sb->feature_map |=
                                 cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
@@ -1917,6 +1934,14 @@ static void sync_sbs(mddev_t * mddev, int nospares)
          */
         mdk_rdev_t *rdev;
 
+        /* First make sure individual recovery_offsets are correct */
+        list_for_each_entry(rdev, &mddev->disks, same_set) {
+                if (rdev->raid_disk >= 0 &&
+                    !test_bit(In_sync, &rdev->flags) &&
+                    mddev->curr_resync_completed > rdev->recovery_offset)
+                                rdev->recovery_offset = mddev->curr_resync_completed;
+
+        }       
         list_for_each_entry(rdev, &mddev->disks, same_set) {
                 if (rdev->sb_events == mddev->events ||
                     (nospares &&
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index dcce204b6c73..d29215d966da 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4823,11 +4823,40 @@ 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"
@@ -4861,6 +4890,7 @@ static int run(mddev_t *mddev)
                                "on a stripe boundary\n");
                         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 *
@@ -4916,10 +4946,51 @@ 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;
+                        
+                printk("%d: w=%d pa=%d pr=%d m=%d a=%d r=%d op1=%d op2=%d\n",
+                       rdev->raid_disk, working_disks, conf->prev_algo,
+                       conf->previous_raid_disks, conf->max_degraded,
+                       conf->algorithm, conf->raid_disks, 
+                       only_parity(rdev->raid_disk,
+                                   conf->prev_algo,
+                                   conf->previous_raid_disks,
+                                   conf->max_degraded),
+                       only_parity(rdev->raid_disk,
+                                   conf->algorithm,
+                                   conf->raid_disks,
+                                   conf->max_degraded));
+                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 = (max(conf->raid_disks, conf->previous_raid_disks)
                            - working_disks);
@@ -4935,7 +5006,7 @@ 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
@@ -5361,9 +5432,11 @@ 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);
+                                if (rdev->raid_disk >= conf->previous_raid_disks)
+                                        set_bit(In_sync, &rdev->flags);
+                                else
+                                        rdev->recovery_offset = 0;
                                 added_devices++;
-                                rdev->recovery_offset = 0;
                                 sprintf(nm, "rd%d", rdev->raid_disk);
                                 if (sysfs_create_link(&mddev->kobj,
                                                       &rdev->kobj, nm))