DM RAID: Add support for MD RAID10

Support the MD RAID10 personality through dm-raid.c

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 946c73342cdea1c4afb23cb889828856a5e6308d..1c184495716697610d4bb41e1dde3ab60dce9e51 100644 (file)
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -27,6 +27,10 @@ The target is named "raid" and it accepts the following parameters:
                - rotating parity N (right-to-left) with data restart
   raid6_nc     RAID6 N continue
                - rotating parity N (right-to-left) with data continuation
+  raid10        Various RAID10 inspired algorithms chosen by additional params
+               - RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
+               - RAID1E: Integrated Adjacent Stripe Mirroring
+               -  and other similar RAID10 variants
 
   Reference: Chapter 4 of
   http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
@@ -59,6 +63,28 @@ The target is named "raid" and it accepts the following parameters:
                logical size of the array.  The bitmap records the device
                synchronisation state for each region.
 
+        [raid10_copies   <# copies>]
+        [raid10_format   near]
+               These two options are used to alter the default layout of
+               a RAID10 configuration.  The number of copies is can be
+               specified, but the default is 2.  There are other variations
+               to how the copies are laid down - the default and only current
+               option is "near".  Near copies are what most people think of
+               with respect to mirroring.  If these options are left
+               unspecified, or 'raid10_copies 2' and/or 'raid10_format near'
+               are given, then the layouts for 2, 3 and 4 devices are:
+               2 drives         3 drives          4 drives
+               --------         ----------        --------------
+               A1  A1           A1  A1  A2        A1  A1  A2  A2
+               A2  A2           A2  A3  A3        A3  A3  A4  A4
+               A3  A3           A4  A4  A5        A5  A5  A6  A6
+               A4  A4           A5  A6  A6        A7  A7  A8  A8
+               ..  ..           ..  ..  ..        ..  ..  ..  ..
+               The 2-device layout is equivalent 2-way RAID1.  The 4-device
+               layout is what a traditional RAID10 would look like.  The
+               3-device layout is what might be called a 'RAID1E - Integrated
+               Adjacent Stripe Mirroring'.
+
 <#raid_devs>: The number of devices composing the array.
        Each device consists of two entries.  The first is the device
        containing the metadata (if any); the second is the one containing the

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index f4275a8e860c310ed6e59eb3f4592c045ec2cb2d..691b3c59088e1a479ff26a22f2cb51eacb813160 100644 (file)
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -11,6 +11,7 @@
 #include "md.h"
 #include "raid1.h"
 #include "raid5.h"
+#include "raid10.h"
 #include "bitmap.h"
 
 #include <linux/device-mapper.h>
@@ -52,7 +53,10 @@ struct raid_dev {
 #define DMPF_MAX_RECOVERY_RATE 0x20
 #define DMPF_MAX_WRITE_BEHIND  0x40
 #define DMPF_STRIPE_CACHE      0x80
-#define DMPF_REGION_SIZE       0X100
+#define DMPF_REGION_SIZE       0x100
+#define DMPF_RAID10_COPIES     0x200
+#define DMPF_RAID10_FORMAT     0x400
+
 struct raid_set {
        struct dm_target *ti;
 
@@ -76,6 +80,7 @@ static struct raid_type {
        const unsigned algorithm;       /* RAID algorithm. */
 } raid_types[] = {
        {"raid1",    "RAID1 (mirroring)",               0, 2, 1, 0 /* NONE */},
+       {"raid10",   "RAID10 (striped mirrors)",        0, 2, 10, UINT_MAX /* Varies */},
        {"raid4",    "RAID4 (dedicated parity disk)",   1, 2, 5, ALGORITHM_PARITY_0},
        {"raid5_la", "RAID5 (left asymmetric)",         1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
        {"raid5_ra", "RAID5 (right asymmetric)",        1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
@@ -86,6 +91,17 @@ static struct raid_type {
        {"raid6_nc", "RAID6 (N continue)",              2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
 };
 
+static unsigned raid10_md_layout_to_copies(int layout)
+{
+       return layout & 0xFF;
+}
+
+static int raid10_format_to_md_layout(char *format, unsigned copies)
+{
+       /* 1 "far" copy, and 'copies' "near" copies */
+       return (1 << 8) | (copies & 0xFF);
+}
+
 static struct raid_type *get_raid_type(char *name)
 {
        int i;
@@ -339,10 +355,16 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
  *    [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
+ *
+ * RAID10-only options:
+ *    [raid10_copies <# copies>]        Number of copies.  (Default: 2)
+ *    [raid10_format <near>]            Layout algorithm.  (Default: near)
  */
 static int parse_raid_params(struct raid_set *rs, char **argv,
                             unsigned num_raid_params)
 {
+       char *raid10_format = "near";
+       unsigned raid10_copies = 2;
        unsigned i, rebuild_cnt = 0;
        unsigned long value, region_size = 0;
        sector_t sectors_per_dev = rs->ti->len;
@@ -416,11 +438,28 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                }
 
                key = argv[i++];
+
+               /* Parameters that take a string value are checked here. */
+               if (!strcasecmp(key, "raid10_format")) {
+                       if (rs->raid_type->level != 10) {
+                               rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
+                               return -EINVAL;
+                       }
+                       if (strcmp("near", argv[i])) {
+                               rs->ti->error = "Invalid 'raid10_format' value given";
+                               return -EINVAL;
+                       }
+                       raid10_format = argv[i];
+                       rs->print_flags |= DMPF_RAID10_FORMAT;
+                       continue;
+               }
+
                if (strict_strtoul(argv[i], 10, &value) < 0) {
                        rs->ti->error = "Bad numerical argument given in raid params";
                        return -EINVAL;
                }
 
+               /* Parameters that take a numeric value are checked here */
                if (!strcasecmp(key, "rebuild")) {
                        rebuild_cnt++;
 
@@ -439,6 +478,7 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                                        return -EINVAL;
                                }
                                break;
+                       case 10:
                        default:
                                DMERR("The rebuild parameter is not supported for %s", rs->raid_type->name);
                                rs->ti->error = "Rebuild not supported for this RAID type";
@@ -495,7 +535,8 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                         */
                        value /= 2;
 
-                       if (rs->raid_type->level < 5) {
+                       if ((rs->raid_type->level != 5) &&
+                           (rs->raid_type->level != 6)) {
                                rs->ti->error = "Inappropriate argument: stripe_cache";
                                return -EINVAL;
                        }
@@ -520,6 +561,14 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
                } else if (!strcasecmp(key, "region_size")) {
                        rs->print_flags |= DMPF_REGION_SIZE;
                        region_size = value;
+               } else if (!strcasecmp(key, "raid10_copies") &&
+                          (rs->raid_type->level == 10)) {
+                       if ((value < 2) || (value > 0xFF)) {
+                               rs->ti->error = "Bad value for 'raid10_copies'";
+                               return -EINVAL;
+                       }
+                       rs->print_flags |= DMPF_RAID10_COPIES;
+                       raid10_copies = value;
                } else {
                        DMERR("Unable to parse RAID parameter: %s", key);
                        rs->ti->error = "Unable to parse RAID parameters";
@@ -538,8 +587,22 @@ static int parse_raid_params(struct raid_set *rs, char **argv,
        if (dm_set_target_max_io_len(rs->ti, max_io_len))
                return -EINVAL;
 
-       if ((rs->raid_type->level > 1) &&
-           sector_div(sectors_per_dev, (rs->md.raid_disks - rs->raid_type->parity_devs))) {
+       if (rs->raid_type->level == 10) {
+               if (raid10_copies > rs->md.raid_disks) {
+                       rs->ti->error = "Not enough devices to satisfy specification";
+                       return -EINVAL;
+               }
+
+               /* (Len * #mirrors) / #devices */
+               sectors_per_dev = rs->ti->len * raid10_copies;
+               sector_div(sectors_per_dev, rs->md.raid_disks);
+
+               rs->md.layout = raid10_format_to_md_layout(raid10_format,
+                                                          raid10_copies);
+               rs->md.new_layout = rs->md.layout;
+       } else if ((rs->raid_type->level > 1) &&
+                  sector_div(sectors_per_dev,
+                             (rs->md.raid_disks - rs->raid_type->parity_devs))) {
                rs->ti->error = "Target length not divisible by number of data devices";
                return -EINVAL;
        }
@@ -566,6 +629,9 @@ static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
        if (rs->raid_type->level == 1)
                return md_raid1_congested(&rs->md, bits);
 
+       if (rs->raid_type->level == 10)
+               return md_raid10_congested(&rs->md, bits);
+
        return md_raid5_congested(&rs->md, bits);
 }
 
@@ -884,6 +950,9 @@ static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
        case 6:
                redundancy = rs->raid_type->parity_devs;
                break;
+       case 10:
+               redundancy = raid10_md_layout_to_copies(mddev->layout) - 1;
+               break;
        default:
                ti->error = "Unknown RAID type";
                return -EINVAL;
@@ -1049,12 +1118,19 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
                goto bad;
        }
 
+       if (ti->len != rs->md.array_sectors) {
+               ti->error = "Array size does not match requested target length";
+               ret = -EINVAL;
+               goto size_mismatch;
+       }
        rs->callbacks.congested_fn = raid_is_congested;
        dm_table_add_target_callbacks(ti->table, &rs->callbacks);
 
        mddev_suspend(&rs->md);
        return 0;
 
+size_mismatch:
+       md_stop(&rs->md);
 bad:
        context_free(rs);
 
@@ -1203,6 +1279,13 @@ static int raid_status(struct dm_target *ti, status_type_t type,
                        DMEMIT(" region_size %lu",
                               rs->md.bitmap_info.chunksize >> 9);
 
+               if (rs->print_flags & DMPF_RAID10_COPIES)
+                       DMEMIT(" raid10_copies %u",
+                              raid10_md_layout_to_copies(rs->md.layout));
+
+               if (rs->print_flags & DMPF_RAID10_FORMAT)
+                       DMEMIT(" raid10_format near");
+
                DMEMIT(" %d", rs->md.raid_disks);
                for (i = 0; i < rs->md.raid_disks; i++) {
                        if (rs->dev[i].meta_dev)
@@ -1277,7 +1360,7 @@ static void raid_resume(struct dm_target *ti)
 
 static struct target_type raid_target = {
        .name = "raid",
-       .version = {1, 2, 0},
+       .version = {1, 3, 0},
        .module = THIS_MODULE,
        .ctr = raid_ctr,
        .dtr = raid_dtr,
@@ -1304,6 +1387,8 @@ module_init(dm_raid_init);
 module_exit(dm_raid_exit);
 
 MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_ALIAS("dm-raid1");
+MODULE_ALIAS("dm-raid10");
 MODULE_ALIAS("dm-raid4");
 MODULE_ALIAS("dm-raid5");
 MODULE_ALIAS("dm-raid6");