dm raid: add write_mostly parameter

Add the write_mostly parameter to RAID1 dm-raid tables.

This allows the user to set the WriteMostly flag on a RAID1 device that
should normally be avoided for read I/O.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 25 insertions, 1 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index a8a1915a450d..88143a0303d2 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -308,6 +308,7 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
  *    [daemon_sleep <ms>]               Time between bitmap daemon work to clear bits
  *    [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
  *    [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
+ *    [write_mostly <idx>]              Indicate a write mostly drive via index
  *    [max_write_behind <sectors>]      See '-write-behind=' (man mdadm)
  *    [stripe_cache <sectors>]          Stripe cache size for higher RAIDs
  *    [region_size <sectors>]           Defines granularity of bitmap
@@ -376,7 +377,21 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                         clear_bit(In_sync, &rs->dev[value].rdev.flags);
                         rs->dev[value].rdev.recovery_offset = 0;
                         rs->print_flags |= DMPF_REBUILD;
+                } else if (!strcasecmp(key, "write_mostly")) {
+                        if (rs->raid_type->level != 1) {
+                                rs->ti->error = "write_mostly option is only valid for RAID1";
+                                return -EINVAL;
+                        }
+                        if (value > rs->md.raid_disks) {
+                                rs->ti->error = "Invalid write_mostly drive index given";
+                                return -EINVAL;
+                        }
+                        set_bit(WriteMostly, &rs->dev[value].rdev.flags);
                 } else if (!strcasecmp(key, "max_write_behind")) {
+                        if (rs->raid_type->level != 1) {
+                                rs->ti->error = "max_write_behind option is only valid for RAID1";
+                                return -EINVAL;
+                        }
                         rs->print_flags |= DMPF_MAX_WRITE_BEHIND;
 
                         /*
@@ -621,11 +636,15 @@ static int raid_status(struct dm_target *ti, status_type_t type,
                 break;
         case STATUSTYPE_TABLE:
                 /* The string you would use to construct this array */
-                for (i = 0; i < rs->md.raid_disks; i++)
+                for (i = 0; i < rs->md.raid_disks; i++) {
                         if ((rs->print_flags & DMPF_REBUILD) &&
                             rs->dev[i].data_dev &&
                             !test_bit(In_sync, &rs->dev[i].rdev.flags))
                                 raid_param_cnt += 2; /* for rebuilds */
+                        if (rs->dev[i].data_dev &&
+                            test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+                                raid_param_cnt += 2;
+                }
 
                 raid_param_cnt += (hweight64(rs->print_flags & ~DMPF_REBUILD) * 2);
                 if (rs->print_flags & (DMPF_SYNC | DMPF_NOSYNC))
@@ -656,6 +675,11 @@ static int raid_status(struct dm_target *ti, status_type_t type,
                 if (rs->print_flags & DMPF_MAX_RECOVERY_RATE)
                         DMEMIT(" max_recovery_rate %d", rs->md.sync_speed_max);
 
+                for (i = 0; i < rs->md.raid_disks; i++)
+                        if (rs->dev[i].data_dev &&
+                            test_bit(WriteMostly, &rs->dev[i].rdev.flags))
+                                DMEMIT(" write_mostly %u", i);
+
                 if (rs->print_flags & DMPF_MAX_WRITE_BEHIND)
                         DMEMIT(" max_write_behind %lu",
                                rs->md.bitmap_info.max_write_behind);