dm raid: enhance reshape check and factor out reshape setup

Enhance rs_reshape_requested() check function to be more transparent and
fix its raid10 check.

Streamline the constructor by factoring out reshaping preparation into
fucntion rs_prepare_reshape().

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 846c58d2bcf92653375f8ad5642cd0b63d0447dc..473c6d9765f01e9f0e7a7d463a958901d61d72db 100644 (file)
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1700,16 +1700,30 @@ static bool rs_takeover_requested(struct raid_set *rs)
 /* True if @rs is requested to reshape by ctr */
 static bool rs_reshape_requested(struct raid_set *rs)
 {
+       bool change;
        struct mddev *mddev = &rs->md;
 
+       if (rs_takeover_requested(rs))
+               return false;
+
        if (!mddev->level)
                return false;
 
-       return !__is_raid10_far(mddev->new_layout) &&
-              mddev->new_level == mddev->level &&
-              (mddev->new_layout != mddev->layout ||
-               mddev->new_chunk_sectors != mddev->chunk_sectors ||
-               rs->raid_disks + rs->delta_disks != mddev->raid_disks);
+       change = mddev->new_layout != mddev->layout ||
+                mddev->new_chunk_sectors != mddev->chunk_sectors ||
+                rs->delta_disks;
+
+       /* Historical case to support raid1 reshape without delta disks */
+       if (mddev->level == 1)
+               return !change &&
+                      mddev->raid_disks != rs->raid_disks;
+
+       if (mddev->level == 10)
+               return change &&
+                      !__is_raid10_far(mddev->new_layout) &&
+                      rs->delta_disks >= 0;
+
+       return change;
 }
 
 /*  Features */
@@ -1821,7 +1835,7 @@ static int rs_check_reshape(struct raid_set *rs)
                rs->ti->error = "Can't reshape degraded raid set";
        else if (rs_is_recovering(rs))
                rs->ti->error = "Convert request on recovering raid set prohibited";
-       else if (mddev->reshape_position && rs_is_reshaping(rs))
+       else if (rs_is_reshaping(rs))
                rs->ti->error = "raid set already reshaping!";
        else if (!(rs_is_raid10(rs) || rs_is_raid456(rs)))
                rs->ti->error = "Reshaping only supported for raid4/5/6/10";
@@ -2518,6 +2532,69 @@ static int rs_setup_takeover(struct raid_set *rs)
        return 0;
 }
 
+/* Prepare @rs for reshape */
+static int rs_prepare_reshape(struct raid_set *rs)
+{
+       bool reshape;
+       struct mddev *mddev = &rs->md;
+
+       if (rs_is_raid10(rs)) {
+               if (rs->raid_disks != mddev->raid_disks &&
+                   __is_raid10_near(mddev->layout) &&
+                   rs->raid10_copies &&
+                   rs->raid10_copies != __raid10_near_copies(mddev->layout)) {
+                       /*
+                        * raid disk have to be multiple of data copies to allow this conversion,
+                        *
+                        * This is actually not a reshape it is a
+                        * rebuild of any additional mirrors per group
+                        */
+                       if (rs->raid_disks % rs->raid10_copies) {
+                               rs->ti->error = "Can't reshape raid10 mirror groups";
+                               return -EINVAL;
+                       }
+
+                       /* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
+                       __reorder_raid_disk_indexes(rs);
+                       mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
+                                                                  rs->raid10_copies);
+                       mddev->new_layout = mddev->layout;
+                       reshape = false;
+               } else
+                       reshape = true;
+
+       } else if (rs_is_raid456(rs))
+               reshape = true;
+
+       /*
+        * HM FIXME: process raid1 via delta_disks as well?
+        *           Would cause allocations in raid1->check_reshape
+        *           though, thus more issues with potential failures
+        */
+       else if (rs_is_raid1(rs)) {
+               set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+               mddev->raid_disks = rs->raid_disks;
+               reshape = false;
+
+       } else {
+               rs->ti->error = "Called with bogus raid type";
+               return -EINVAL;
+       }
+
+       if (reshape) {
+               set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
+               set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+               set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+       }
+       /* Create new superblocks and bitmaps, if any */
+       if (mddev->raid_disks < rs->raid_disks) {
+               set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+               rs_set_cur(rs);
+       }
+
+       return 0;
+}
+
 /*
  *
  * - change raid layout
@@ -2682,7 +2759,7 @@ static void configure_discard_support(struct raid_set *rs)
 static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
        int r;
-       bool resize = false;
+       bool resize;
        struct raid_type *rt;
        unsigned num_raid_params, num_raid_devs;
        sector_t calculated_dev_sectors;
@@ -2770,6 +2847,12 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
        /* Restore any requested new layout for conversion decision */
        rs_config_restore(rs, &rs_layout);
 
+       /*
+        * Now that we have any superblock metadata available,
+        * check for new, recovering, reshaping, to be taken over,
+        * to be reshaped or an existing, unchanged raid set to
+        * run in sequence.
+        */
        if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
                /* A new raid6 set has to be recovered to ensure proper parity and Q-Syndrome */
                if (rs_is_raid6(rs) &&
@@ -2782,6 +2865,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
                set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
                rs_set_new(rs);
        } else if (rs_is_recovering(rs)) {
+               /* A recovering raid set may be resized */
                ; /* skip setup rs */
        } else if (rs_is_reshaping(rs)) {
                /* Have to reject size change request during reshape */
@@ -2790,7 +2874,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
                        r = -EPERM;
                        goto bad;
                }
-               ; /* skip setup rs */
+               /* skip setup rs */
        } else if (rs_takeover_requested(rs)) {
                if (rs_is_reshaping(rs)) {
                        ti->error = "Can't takeover a reshaping raid set";
@@ -2800,7 +2884,9 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
                /*
                 * If a takeover is needed, userspace sets any additional
-                * devices to rebuild, so set the level to the new requested
+                * devices to rebuild and we can check for a valid request here.
+                *
+                * If acceptible, set the level to the new requested
                 * one, prohibit requesting recovery, allow the raid
                 * set to run and store superblocks during resume.
                 */
@@ -2814,63 +2900,22 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
                set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
                set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
+               /* Takeover ain't recovery, so disable recovery */
                rs_setup_recovery(rs, MaxSector);
                rs_set_new(rs);
        } else if (rs_reshape_requested(rs)) {
-               if (rs_is_reshaping(rs)) {
-                       ti->error = "raid set already reshaping!";
-                       r = -EPERM;
-                       goto bad;
-               }
-
-               if (rs_is_raid10(rs)) {
-                       if (rs->raid_disks != rs->md.raid_disks &&
-                           __is_raid10_near(rs->md.layout) &&
-                           rs->raid10_copies &&
-                           rs->raid10_copies != __raid10_near_copies(rs->md.layout)) {
-                               /*
-                                * raid disk have to be multiple of data copies to allow this conversion,
-                                *
-                                * This is actually not a reshape it is a
-                                * rebuild of any additional mirrors per group
-                                */
-                               if (rs->raid_disks % rs->raid10_copies) {
-                                       ti->error = "Can't reshape raid10 mirror groups";
-                                       r = -EINVAL;
-                                       goto bad;
-                               }
-
-                               /* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
-                               __reorder_raid_disk_indexes(rs);
-                               rs->md.layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
-                                                                          rs->raid10_copies);
-                               rs->md.new_layout = rs->md.layout;
-
-                       } else
-                               set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
-
-               } else if (rs_is_raid456(rs))
-                       set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
-
                /*
-                * HM FIXME: process raid1 via delta_disks as well?
-                *           Would cause allocations in raid1->check_reshape
-                *           though, thus more issues with potential failures
-                */
-               else if (rs_is_raid1(rs)) {
-                       set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
-                       rs->md.raid_disks = rs->raid_disks;
-               }
-
-               if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
-                       set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
-                       set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);
-               }
-
-               /* Create new superblocks and bitmaps, if any */
-               if (rs->md.raid_disks < rs->raid_disks)
-                       set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+                 * We can only prepare for a reshape here, because the
+                 * raid set needs to run to provide the repective reshape
+                 * check functions via its MD personality instance.
+                 *
+                 * So do the reshape check after md_run() succeeded.
+                 */
+               r = rs_prepare_reshape(rs);
+               if (r)
+                       return r;
 
+               /* Reshaping ain't recovery, so disable recovery */
                rs_setup_recovery(rs, MaxSector);
                rs_set_cur(rs);
        } else {