A kernel patch needed to add a spare to an active external-metadata array

diff --git a/kernel-patch-2.6.25 b/kernel-patch-2.6.25
new file mode 100644 (file)
index 0000000..d42bf31
--- /dev/null
+++ b/kernel-patch-2.6.25
@@ -0,0 +1,199 @@
+Status: ok
+
+Support adding a spare to a live md array with external metadata.
+
+i.e. extend the 'md/dev-XXX/slot' attribute so that you can
+tell a device to fill an vacant slot in an and md array.
+
+
+Signed-off-by: Neil Brown <neilb@suse.de>
+
+### Diffstat output
+ ./drivers/md/md.c        |   44 ++++++++++++++++++++++++++++++++++++++++----
+ ./drivers/md/multipath.c |    7 ++++++-
+ ./drivers/md/raid1.c     |    7 ++++++-
+ ./drivers/md/raid10.c    |   10 ++++++++--
+ ./drivers/md/raid5.c     |   10 ++++++++--
+ 5 files changed, 68 insertions(+), 10 deletions(-)
+
+diff .prev/drivers/md/md.c ./drivers/md/md.c
+--- .prev/drivers/md/md.c      2008-06-05 09:19:56.000000000 +1000
++++ ./drivers/md/md.c  2008-06-10 10:41:21.000000000 +1000
+@@ -1932,7 +1932,7 @@ slot_store(mdk_rdev_t *rdev, const char 
+               slot = -1;
+       else if (e==buf || (*e && *e!= '\n'))
+               return -EINVAL;
+-      if (rdev->mddev->pers) {
++      if (rdev->mddev->pers && slot == -1) {
+               /* Setting 'slot' on an active array requires also
+                * updating the 'rd%d' link, and communicating
+                * with the personality with ->hot_*_disk.
+@@ -1940,8 +1940,6 @@ slot_store(mdk_rdev_t *rdev, const char 
+                * failed/spare devices.  This normally happens automatically,
+                * but not when the metadata is externally managed.
+                */
+-              if (slot != -1)
+-                      return -EBUSY;
+               if (rdev->raid_disk == -1)
+                       return -EEXIST;
+               /* personality does all needed checks */
+@@ -1955,6 +1953,44 @@ slot_store(mdk_rdev_t *rdev, const char 
+               sysfs_remove_link(&rdev->mddev->kobj, nm);
+               set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+               md_wakeup_thread(rdev->mddev->thread);
++      } else if (rdev->mddev->pers) {
++              mdk_rdev_t *rdev2;
++              struct list_head *tmp;
++              /* Activating a spare .. or possibly reactivating
++               * if we every get bitmaps working here.
++               */
++
++              if (rdev->raid_disk != -1)
++                      return -EBUSY;
++
++              if (rdev->mddev->pers->hot_add_disk == NULL)
++                      return -EINVAL;
++
++              rdev_for_each(rdev2, tmp, rdev->mddev)
++                      if (rdev2->raid_disk == slot)
++                              return -EEXIST;
++
++              rdev->raid_disk = slot;
++              if (test_bit(In_sync, &rdev->flags))
++                      rdev->saved_raid_disk = slot;
++              else
++                      rdev->saved_raid_disk = -1;
++              err = rdev->mddev->pers->
++                      hot_add_disk(rdev->mddev, rdev);
++              if (err != 1) {
++                      rdev->raid_disk = -1;
++                      if (err == 0)
++                              return -EEXIST;
++                      return err;
++              }
++              sprintf(nm, "rd%d", rdev->raid_disk);
++              if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
++                      printk(KERN_WARNING
++                             "md: cannot register "
++                             "%s for %s\n",
++                             nm, mdname(rdev->mddev));
++
++              /* don't wakeup anyone, leave that to userspace. */
+       } else {
+               if (slot >= rdev->mddev->raid_disks)
+                       return -ENOSPC;
+@@ -4205,7 +4241,7 @@ static int add_new_disk(mddev_t * mddev,
+                       super_types[mddev->major_version].
+                               validate_super(mddev, rdev);
+                       err = mddev->pers->hot_add_disk(mddev, rdev);
+-                      if (err)
++                      if (err < 0)
+                               unbind_rdev_from_array(rdev);
+               }
+               if (err)
+
+diff .prev/drivers/md/multipath.c ./drivers/md/multipath.c
+--- .prev/drivers/md/multipath.c       2008-05-30 14:49:31.000000000 +1000
++++ ./drivers/md/multipath.c   2008-06-10 10:35:03.000000000 +1000
+@@ -284,10 +284,15 @@ static int multipath_add_disk(mddev_t *m
+       int found = 0;
+       int path;
+       struct multipath_info *p;
++      int first = 0;
++      int last = mddev->raid_disks - 1;
++
++      if (rdev->raid_disk >= 0)
++              first = last = rdev->raid_disk;
+ 
+       print_multipath_conf(conf);
+ 
+-      for (path=0; path<mddev->raid_disks; path++) 
++      for (path = first; path <= last; path++)
+               if ((p=conf->multipaths+path)->rdev == NULL) {
+                       q = rdev->bdev->bd_disk->queue;
+                       blk_queue_stack_limits(mddev->queue, q);
+
+diff .prev/drivers/md/raid10.c ./drivers/md/raid10.c
+--- .prev/drivers/md/raid10.c  2008-05-30 14:49:31.000000000 +1000
++++ ./drivers/md/raid10.c      2008-06-10 10:28:53.000000000 +1000
+@@ -1116,6 +1116,8 @@ static int raid10_add_disk(mddev_t *mdde
+       int found = 0;
+       int mirror;
+       mirror_info_t *p;
++      int first = 0;
++      int last = mddev->raid_disks;
+ 
+       if (mddev->recovery_cp < MaxSector)
+               /* only hot-add to in-sync arrays, as recovery is
+@@ -1125,12 +1127,16 @@ static int raid10_add_disk(mddev_t *mdde
+       if (!enough(conf))
+               return 0;
+ 
++      if (rdev->raid_disk)
++              first = last = rdev->raid_disk;
++
+       if (rdev->saved_raid_disk >= 0 &&
++          rdev->saved_raid_disk >= first &&
+           conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
+               mirror = rdev->saved_raid_disk;
+       else
+-              mirror = 0;
+-      for ( ; mirror < mddev->raid_disks; mirror++)
++              mirror = first;
++      for ( ; mirror <= last ; mirror++)
+               if ( !(p=conf->mirrors+mirror)->rdev) {
+ 
+                       blk_queue_stack_limits(mddev->queue,
+
+diff .prev/drivers/md/raid1.c ./drivers/md/raid1.c
+--- .prev/drivers/md/raid1.c   2008-05-30 14:49:31.000000000 +1000
++++ ./drivers/md/raid1.c       2008-06-10 10:41:00.000000000 +1000
+@@ -1103,8 +1103,13 @@ static int raid1_add_disk(mddev_t *mddev
+       int found = 0;
+       int mirror = 0;
+       mirror_info_t *p;
++      int first = 0;
++      int last = mddev->raid_disks - 1;
+ 
+-      for (mirror=0; mirror < mddev->raid_disks; mirror++)
++      if (rdev->raid_disk >= 0)
++              first = last = rdev->raid_disk;
++
++      for (mirror = first; mirror <= last; mirror++)
+               if ( !(p=conf->mirrors+mirror)->rdev) {
+ 
+                       blk_queue_stack_limits(mddev->queue,
+
+diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
+--- .prev/drivers/md/raid5.c   2008-05-30 14:49:35.000000000 +1000
++++ ./drivers/md/raid5.c       2008-06-10 10:27:51.000000000 +1000
+@@ -4399,21 +4399,27 @@ static int raid5_add_disk(mddev_t *mddev
+       int found = 0;
+       int disk;
+       struct disk_info *p;
++      int first = 0;
++      int last = conf->raid_disks - 1;
+ 
+       if (mddev->degraded > conf->max_degraded)
+               /* no point adding a device */
+               return 0;
+ 
++      if (rdev->raid_disk >= 0)
++              first = last = rdev->raid_disk;
++
+       /*
+        * find the disk ... but prefer rdev->saved_raid_disk
+        * if possible.
+        */
+       if (rdev->saved_raid_disk >= 0 &&
++          rdev->saved_raid_disk >= first &&
+           conf->disks[rdev->saved_raid_disk].rdev == NULL)
+               disk = rdev->saved_raid_disk;
+       else
+-              disk = 0;
+-      for ( ; disk < conf->raid_disks; disk++)
++              disk = first;
++      for ( ; disk <= last ; disk++)
+               if ((p=conf->disks + disk)->rdev == NULL) {
+                       clear_bit(In_sync, &rdev->flags);
+                       rdev->raid_disk = disk;