Merge tag 'md-3.3' of git://neil.brown.name/md

md update for 3.3

Big change is new hot-replacement.
A slot in an array can hold 2 devices - one that
wants-replacement and one that is the replacement.
Once the replacement is built - either from the
original or (in the case of errors) from elsewhere,
the wants-replacement device will be removed.

* tag 'md-3.3' of git://neil.brown.name/md: (36 commits)
  md/raid1: Mark device want_replacement when we see a write error.
  md/raid1: If there is a spare and a want_replacement device, start replacement.
  md/raid1: recognise replacements when assembling arrays.
  md/raid1: handle activation of replacement device when recovery completes.
  md/raid1: Allow a failed replacement device to be removed.
  md/raid1: Allocate spare to store replacement devices and their bios.
  md/raid1:  Replace use of mddev->raid_disks with conf->raid_disks.
  md/raid10: If there is a spare and a want_replacement device, start replacement.
  md/raid10: recognise replacements when assembling array.
  md/raid10: Allow replacement device to be replace old drive.
  md/raid10: handle recovery of replacement devices.
  md/raid10:  Handle replacement devices during resync.
  md/raid10: writes should get directed to replacement as well as original.
  md/raid10: allow removal of failed replacement devices.
  md/raid10: preferentially read from replacement device if possible.
  md/raid10:  change read_balance to return an rdev
  md/raid10: prepare data structures for handling replacement.
  md/raid5: Mark device want_replacement when we see a write error.
  md/raid5: If there is a spare and a want_replacement device, start replacement.
  md/raid5: recognise replacements when assembling array.
  ...

diff --combined drivers/md/md.c
index 5d1b6762f108263f5e9ea7861215543b34b42685,1c1c562f63dcf8e5a3889f66d05bf2272359cbbc..ca8527fe77ebe1a8ddfb5a7adc2d21ee79123319
--- 1/drivers/md/md.c
--- 2/drivers/md/md.c
+++ b/drivers/md/md.c
@@@ -36,7 -36,8 +36,7 @@@
  #include <linux/blkdev.h>
  #include <linux/sysctl.h>
  #include <linux/seq_file.h>
 -#include <linux/mutex.h>
 -#include <linux/buffer_head.h> /* for invalidate_bdev */
 +#include <linux/fs.h>
  #include <linux/poll.h>
  #include <linux/ctype.h>
  #include <linux/string.h>
@@@ -1713,6 -1714,8 +1713,8 @@@ static int super_1_validate(struct mdde
                }
                if (sb->devflags & WriteMostly1)
                        set_bit(WriteMostly, &rdev->flags);
+               if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
+                       set_bit(Replacement, &rdev->flags);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);
  
@@@ -1766,6 -1769,9 +1768,9 @@@ static void super_1_sync(struct mddev *
                sb->recovery_offset =
                        cpu_to_le64(rdev->recovery_offset);
        }
+       if (test_bit(Replacement, &rdev->flags))
+               sb->feature_map |=
+                       cpu_to_le32(MD_FEATURE_REPLACEMENT);
  
        if (mddev->reshape_position != MaxSector) {
                sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
@@@ -2559,6 -2565,15 +2564,15 @@@ state_show(struct md_rdev *rdev, char *
                len += sprintf(page+len, "%swrite_error", sep);
                sep = ",";
        }
+       if (test_bit(WantReplacement, &rdev->flags)) {
+               len += sprintf(page+len, "%swant_replacement", sep);
+               sep = ",";
+       }
+       if (test_bit(Replacement, &rdev->flags)) {
+               len += sprintf(page+len, "%sreplacement", sep);
+               sep = ",";
+       }
+ 
        return len+sprintf(page+len, "\n");
  }
  
@@@ -2627,6 -2642,42 +2641,42 @@@ state_store(struct md_rdev *rdev, cons
        } else if (cmd_match(buf, "-write_error")) {
                clear_bit(WriteErrorSeen, &rdev->flags);
                err = 0;
+       } else if (cmd_match(buf, "want_replacement")) {
+               /* Any non-spare device that is not a replacement can
+                * become want_replacement at any time, but we then need to
+                * check if recovery is needed.
+                */
+               if (rdev->raid_disk >= 0 &&
+                   !test_bit(Replacement, &rdev->flags))
+                       set_bit(WantReplacement, &rdev->flags);
+               set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+               md_wakeup_thread(rdev->mddev->thread);
+               err = 0;
+       } else if (cmd_match(buf, "-want_replacement")) {
+               /* Clearing 'want_replacement' is always allowed.
+                * Once replacements starts it is too late though.
+                */
+               err = 0;
+               clear_bit(WantReplacement, &rdev->flags);
+       } else if (cmd_match(buf, "replacement")) {
+               /* Can only set a device as a replacement when array has not
+                * yet been started.  Once running, replacement is automatic
+                * from spares, or by assigning 'slot'.
+                */
+               if (rdev->mddev->pers)
+                       err = -EBUSY;
+               else {
+                       set_bit(Replacement, &rdev->flags);
+                       err = 0;
+               }
+       } else if (cmd_match(buf, "-replacement")) {
+               /* Similarly, can only clear Replacement before start */
+               if (rdev->mddev->pers)
+                       err = -EBUSY;
+               else {
+                       clear_bit(Replacement, &rdev->flags);
+                       err = 0;
+               }
        }
        if (!err)
                sysfs_notify_dirent_safe(rdev->sysfs_state);
@@@ -2688,7 -2739,7 +2738,7 @@@ slot_store(struct md_rdev *rdev, const 
                if (rdev->mddev->pers->hot_remove_disk == NULL)
                        return -EINVAL;
                err = rdev->mddev->pers->
-                       hot_remove_disk(rdev->mddev, rdev->raid_disk);
+                       hot_remove_disk(rdev->mddev, rdev);
                if (err)
                        return err;
                sysfs_unlink_rdev(rdev->mddev, rdev);
@@@ -2696,7 -2747,6 +2746,6 @@@
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);
        } else if (rdev->mddev->pers) {
-               struct md_rdev *rdev2;
                /* Activating a spare .. or possibly reactivating
                 * if we ever get bitmaps working here.
                 */
@@@ -2710,10 -2760,6 +2759,6 @@@
                if (rdev->mddev->pers->hot_add_disk == NULL)
                        return -EINVAL;
  
-               list_for_each_entry(rdev2, &rdev->mddev->disks, same_set)
-                       if (rdev2->raid_disk == slot)
-                               return -EEXIST;
- 
                if (slot >= rdev->mddev->raid_disks &&
                    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
                        return -ENOSPC;
@@@ -6053,8 -6099,15 +6098,15 @@@ static int md_ioctl(struct block_devic
        struct mddev *mddev = NULL;
        int ro;
  
-       if (!capable(CAP_SYS_ADMIN))
-               return -EACCES;
+       switch (cmd) {
+       case RAID_VERSION:
+       case GET_ARRAY_INFO:
+       case GET_DISK_INFO:
+               break;
+       default:
+               if (!capable(CAP_SYS_ADMIN))
+                       return -EACCES;
+       }
  
        /*
         * Commands dealing with the RAID driver but not any
@@@ -6714,8 -6767,11 +6766,11 @@@ static int md_seq_show(struct seq_file 
                        if (test_bit(Faulty, &rdev->flags)) {
                                seq_printf(seq, "(F)");
                                continue;
-                       } else if (rdev->raid_disk < 0)
+                       }
+                       if (rdev->raid_disk < 0)
                                seq_printf(seq, "(S)"); /* spare */
+                       if (test_bit(Replacement, &rdev->flags))
+                               seq_printf(seq, "(R)");
                        sectors += rdev->sectors;
                }
  
@@@ -7337,29 -7393,27 +7392,27 @@@ static int remove_and_add_spares(struc
                     ! test_bit(In_sync, &rdev->flags)) &&
                    atomic_read(&rdev->nr_pending)==0) {
                        if (mddev->pers->hot_remove_disk(
-                                   mddev, rdev->raid_disk)==0) {
+                                   mddev, rdev) == 0) {
                                sysfs_unlink_rdev(mddev, rdev);
                                rdev->raid_disk = -1;
                        }
                }
  
-       if (mddev->degraded) {
-               list_for_each_entry(rdev, &mddev->disks, same_set) {
-                       if (rdev->raid_disk >= 0 &&
-                           !test_bit(In_sync, &rdev->flags) &&
-                           !test_bit(Faulty, &rdev->flags))
+       list_for_each_entry(rdev, &mddev->disks, same_set) {
+               if (rdev->raid_disk >= 0 &&
+                   !test_bit(In_sync, &rdev->flags) &&
+                   !test_bit(Faulty, &rdev->flags))
+                       spares++;
+               if (rdev->raid_disk < 0
+                   && !test_bit(Faulty, &rdev->flags)) {
+                       rdev->recovery_offset = 0;
+                       if (mddev->pers->
+                           hot_add_disk(mddev, rdev) == 0) {
+                               if (sysfs_link_rdev(mddev, rdev))
+                                       /* failure here is OK */;
                                spares++;
-                       if (rdev->raid_disk < 0
-                           && !test_bit(Faulty, &rdev->flags)) {
-                               rdev->recovery_offset = 0;
-                               if (mddev->pers->
-                                   hot_add_disk(mddev, rdev) == 0) {
-                                       if (sysfs_link_rdev(mddev, rdev))
-                                               /* failure here is OK */;
-                                       spares++;
-                                       md_new_event(mddev);
-                                       set_bit(MD_CHANGE_DEVS, &mddev->flags);
-                               }
+                               md_new_event(mddev);
+                               set_bit(MD_CHANGE_DEVS, &mddev->flags);
                        }
                }
        }
@@@ -7474,7 -7528,7 +7527,7 @@@ void md_check_recovery(struct mddev *md
                                    test_bit(Faulty, &rdev->flags) &&
                                    atomic_read(&rdev->nr_pending)==0) {
                                        if (mddev->pers->hot_remove_disk(
-                                                   mddev, rdev->raid_disk)==0) {
+                                                   mddev, rdev) == 0) {
                                                sysfs_unlink_rdev(mddev, rdev);
                                                rdev->raid_disk = -1;
                                        }