[dm-devel] [PATCH 21/26] dm raid: found way to allow resize during shrink

[heinzm at redhat.com]

From: Heinz Mauelshagen <heinzm at redhat.com>

Signed-off-by: Heinz Mauelshagen <heinzm at redhat.com>
---
 drivers/md/dm-raid.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 1ff469f..846c58d 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -2682,6 +2682,7 @@ 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;
 	struct raid_type *rt;
 	unsigned num_raid_params, num_raid_devs;
 	sector_t calculated_dev_sectors;
@@ -2760,7 +2761,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	if (r)
 		goto bad;
 
-	rs_setup_recovery(rs, calculated_dev_sectors);
+	resize = calculated_dev_sectors != rs->dev[0].rdev.sectors;
 
 	INIT_WORK(&rs->md.event_work, do_table_event);
 	ti->private = rs;
@@ -2770,8 +2771,6 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	rs_config_restore(rs, &rs_layout);
 
 	if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
-		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
-		rs_set_new(rs);
 		/* A new raid6 set has to be recovered to ensure proper parity and Q-Syndrome */
 		if (rs_is_raid6(rs) &&
 		    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
@@ -2780,16 +2779,18 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			goto bad;
 		}
 		rs_setup_recovery(rs, 0);
-	} else if (rs_is_recovering(rs) || rs_is_reshaping(rs)) {
-		/* Have to reject size change request during recovery/reshape */
-		if (calculated_dev_sectors != rs->dev[0].rdev.sectors) {
-			ti->error = rs_is_recovering(rs) ?
-				    "Can't resize a recovering raid set" :
-				    "Can't resize a reshaping raid set";
+		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
+		rs_set_new(rs);
+	} else if (rs_is_recovering(rs)) {
+		; /* skip setup rs */
+	} else if (rs_is_reshaping(rs)) {
+		/* Have to reject size change request during reshape */
+		if (resize) {
+			ti->error = "Can't resize a reshaping raid set";
 			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";
@@ -2799,8 +2800,9 @@ 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 just set the level to the new
-		 * requested one and allow the raid set to run
+		 * devices to rebuild, so set the level to the new requested
+		 * one, prohibit requesting recovery, allow the raid
+		 * set to run and store superblocks during resume.
 		 */
 		r = rs_check_takeover(rs);
 		if (r)
@@ -2812,6 +2814,7 @@ 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);
+		rs_setup_recovery(rs, MaxSector);
 		rs_set_new(rs);
 	} else if (rs_reshape_requested(rs)) {
 		if (rs_is_reshaping(rs)) {
@@ -2868,16 +2871,17 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 		if (rs->md.raid_disks < rs->raid_disks)
 			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
 
-		rs_set_cur(rs);
 		rs_setup_recovery(rs, MaxSector);
-	} else {
 		rs_set_cur(rs);
+	} else {
+		/* May not set recovery when a device rebuild is requested */
 		if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
 			rs_setup_recovery(rs, MaxSector);
 			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
 		} else
 			rs_setup_recovery(rs, test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ?
-					      0 : calculated_dev_sectors);
+					      0 : (resize ? calculated_dev_sectors : MaxSector));
+		rs_set_cur(rs);
 	}
 
 	/* If constructor requested it, change data and new_data offsets */
-- 
2.5.5