Patch name: dm-raid-seed-module.patch This patch is the skeleton for the DM target that will be the bridge from DM to MD (specifically, RAID456). It provides a way to use device-mapper interfaces to the MD RAID456 drivers. The original patch came from Neil Brown. I've changed a bit of the patch, but left the original 'Signed-off-by'. <JB> I also basically copied the RAID descriptions from MD for the Kconfig entry... Signed-off-by: NeilBrown <neilb@xxxxxxx> RFC-by: Jonathan Brassow <jbrassow@xxxxxxxxxx> Index: linux-2.6/drivers/md/Kconfig =================================================================== --- linux-2.6.orig/drivers/md/Kconfig +++ linux-2.6/drivers/md/Kconfig @@ -240,6 +240,28 @@ config DM_MIRROR Allow volume managers to mirror logical volumes, also needed for live data migration tools such as 'pvmove'. +config DM_RAID + tristate "RAID 4/5/6 target (EXPERIMENTAL)" + depends on BLK_DEV_DM && MD_RAID456 && EXPERIMENTAL + ---help--- + A dm target that supports RAID4, RAID5 and RAID6 mappings + + A RAID-5 set of N drives with a capacity of C MB per drive provides + the capacity of C * (N - 1) MB, and protects against a failure + of a single drive. For a given sector (row) number, (N - 1) drives + contain data sectors, and one drive contains the parity protection. + For a RAID-4 set, the parity blocks are present on a single drive, + while a RAID-5 set distributes the parity across the drives in one + of the available parity distribution methods. + + A RAID-6 set of N drives with a capacity of C MB per drive + provides the capacity of C * (N - 2) MB, and protects + against a failure of any two drives. For a given sector + (row) number, (N - 2) drives contain data sectors, and two + drives contains two independent redundancy syndromes. Like + RAID-5, RAID-6 distributes the syndromes across the drives + in one of the available parity distribution methods. + config DM_LOG_USERSPACE tristate "Mirror userspace logging (EXPERIMENTAL)" depends on DM_MIRROR && EXPERIMENTAL && NET Index: linux-2.6/drivers/md/Makefile =================================================================== --- linux-2.6.orig/drivers/md/Makefile +++ linux-2.6/drivers/md/Makefile @@ -36,6 +36,7 @@ obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot obj-$(CONFIG_DM_MIRROR) += dm-mirror.o dm-log.o dm-region-hash.o obj-$(CONFIG_DM_LOG_USERSPACE) += dm-log-userspace.o obj-$(CONFIG_DM_ZERO) += dm-zero.o +obj-$(CONFIG_DM_RAID) += dm-raid.o ifeq ($(CONFIG_DM_UEVENT),y) dm-mod-objs += dm-uevent.o Index: linux-2.6/drivers/md/dm-raid.c =================================================================== --- /dev/null +++ linux-2.6/drivers/md/dm-raid.c @@ -0,0 +1,462 @@ + +/* + * dm-raid - implemented as wrapper for md/raid456 + * + */ +#include <linux/slab.h> +#include "md.h" +#include "raid5.h" +#include "dm.h" + +#define DM_MSG_PREFIX "raid" + +struct raid_dev { + /* + * Two DM devices, one to hold metadata and one to hold the + * actual data/parity. The reason for this is to not confuse + * ti->len and give more flexibility in altering size and + * characteristics. + * + * While it is possible for this device to be associated + * with a different physical device than the data_dev, it + * is intended for it to be the same. + * |--------- Physical Device ---------| + * |- meta_dev -|------ data_dev ------| + */ + struct dm_dev *meta_dev; + struct dm_dev *data_dev; + struct mdk_rdev_s rdev; +}; + +struct raid_set { + struct dm_target *ti; + struct mddev_s md; + struct raid_type *raid_type; + struct raid_dev dev[0]; +}; + +/* Supported raid types and properties. */ +static struct raid_type { + const char *name; /* RAID algorithm. */ + const char *descr; /* Descriptor text for logging. */ + const unsigned parity_devs; /* # of parity devices. */ + const unsigned minimal_devs; /* minimal # of devices in set. */ + const unsigned level; /* RAID level. */ + const unsigned algorithm; /* RAID algorithm. */ +} raid_types[] = { + {"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}, + {"raid5_ls", "RAID5 (left symmetric)", 1, 2, 5, ALGORITHM_LEFT_SYMMETRIC}, + {"raid5_rs", "RAID5 (right symmetric)", 1, 2, 5, ALGORITHM_RIGHT_SYMMETRIC}, + {"raid6_zr", "RAID6 (zero restart)", 2, 4, 6, ALGORITHM_ROTATING_ZERO_RESTART}, + {"raid6_nr", "RAID6 (N restart)", 2, 4, 6, ALGORITHM_ROTATING_N_RESTART}, + {"raid6_nc", "RAID6 (N continue)", 2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE} +}; + +static struct raid_type *get_raid_type(char *name) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(raid_types); i++) + if (strcmp(raid_types[i].name, name) == 0) + return &raid_types[i]; + return NULL; +} + +static struct raid_set * +context_alloc(struct dm_target *ti, struct raid_type *raid_type, long raid_devs) +{ + int i; + struct raid_set *rs; + sector_t sectors_per_dev; + + sectors_per_dev = ti->len; + if (sector_div(sectors_per_dev, (raid_devs - raid_type->parity_devs))) { + ti->error = "Target length not divisible by number of data devices"; + return ERR_PTR(-EINVAL); + } + + rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL); + if (!rs) { + ti->error = "Cannot allocate raid context"; + return ERR_PTR(-ENOMEM); + } + + mddev_init(&rs->md); + + rs->ti = ti; + rs->raid_type = raid_type; + rs->md.raid_disks = raid_devs; + rs->md.level = raid_type->level; + rs->md.new_level = rs->md.level; + rs->md.dev_sectors = sectors_per_dev; + rs->md.layout = raid_type->algorithm; + rs->md.new_layout = rs->md.layout; + rs->md.delta_disks = 0; + + for (i = 0; i < raid_devs; i++) + md_rdev_init(&rs->dev[i].rdev); + + /* + * Remaining items to be initialized by further RAID params: + * rs->md.persistent + * rs->md.external + * rs->md.chunk_sectors + * rs->md.new_chunk_sectors + * rs->md.recovery_cp + */ + + return rs; +} + +static void context_free(struct raid_set *rs) +{ + int i; + for (i = 0; i < rs->md.raid_disks; i++) { + if (rs->dev[i].data_dev) + dm_put_device(rs->ti, rs->dev[i].data_dev); + } + kfree(rs); +} + +/* For every device we have two words + * <meta_dev>: meta device name or '-' if missing + * <data_dev>: data device name or '-' if missing + * + * This code parses those words. + */ +static int dev_parms(struct raid_set *rs, char **argv) +{ + int i; + + for (i = 0; i < rs->md.raid_disks; i++, argv += 2) { + int err = 0; + + rs->dev[i].rdev.raid_disk = i; + + rs->dev[i].meta_dev = NULL; + rs->dev[i].data_dev = NULL; + + /* + * There are no offsets, since there is a separate device + * for data and metadata. + */ + rs->dev[i].rdev.data_offset = 0; + rs->dev[i].rdev.mddev = &rs->md; + + if (strcmp(argv[0], "-") != 0) { + rs->ti->error = "Metadata devices not supported"; + return -EINVAL; + } + + if (strcmp(argv[1], "-") == 0) { + rs->ti->error = "Drive designated for rebuild not specified"; + if (!test_bit(In_sync, &rs->dev[i].rdev.flags) && + (rs->dev[i].rdev.recovery_offset == 0)) + return -EINVAL; + + continue; + } + + err = dm_get_device(rs->ti, argv[1], + dm_table_get_mode(rs->ti->table), + &rs->dev[i].data_dev); + rs->ti->error = "RAID device lookup failure"; + if (err) + return err; + + rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev; + list_add(&rs->dev[i].rdev.same_set, &rs->md.disks); + } + + rs->ti->error = NULL; + return 0; +} + +/* + * Possible arguments are... + * RAID4: + * <chunk_size> <parity_rebuild> [[no]sync] + * RAID5*: + * <chunk_size> <parity_rebuild> [[no]sync] + * RAID6*: + * <chunk_size> <parity_rebuildA> <parity_rebuildB> [[no]sync] + * + * The <parity_rebuild> argument causes the parity drive(s) to be rebuilt + * if they are specified (as an index to the device list). -1 indicates + * the parity drive does not need to be rebuilt. + */ +static int parse_raid_params(struct raid_set *rs, char **argv, + unsigned long num_raid_params) +{ + int i, in_sync; + unsigned long chunk_size; + long rebuild; + + rs->ti->error = "Bad chunk size"; + if ((strict_strtoul(argv[0], 10, &chunk_size) < 0) || + !is_power_of_2(chunk_size) || (chunk_size < 8)) + return -EINVAL; + rs->md.new_chunk_sectors = rs->md.chunk_sectors = chunk_size; + argv++; + num_raid_params--; + + for (i = 0; i < rs->md.raid_disks; i++) + set_bit(In_sync, &rs->dev[i].rdev.flags); + + rs->ti->error = "Cannot parse rebuild-drives"; + for (i = 0; i < rs->raid_type->parity_devs; i++) { + if ((strict_strtol(argv[i], 10, &rebuild) < 0) || + (rebuild < -1) || (rebuild >= rs->md.raid_disks)) + return -EINVAL; + if (rebuild >= 0) { + clear_bit(In_sync, &rs->dev[rebuild].rdev.flags); + rs->dev[rebuild].rdev.recovery_offset = 0; + } + } + argv += i; + num_raid_params -= i; + + in_sync = 0; + for (i = 0; i < rs->md.raid_disks; i++) + if (test_bit(In_sync, &rs->dev[i].rdev.flags)) + in_sync++; + rs->ti->error = "Insufficient active RAID devices"; + if (rs->md.raid_disks - in_sync > rs->raid_type->parity_devs) + return -EINVAL; + + rs->ti->error = "Bad RAID option"; + if (num_raid_params) { + if (!strcmp(argv[0], "nosync")) + rs->md.recovery_cp = MaxSector; + else if (!strcmp(argv[0], "sync")) + rs->md.recovery_cp = 0; + else + return -EINVAL; + } + + rs->md.persistent = 0; + rs->md.external = 1; + + rs->ti->error = NULL; + return 0; +} + +static void do_table_event(struct work_struct *ws) +{ + struct raid_set *rs = container_of(ws, struct raid_set, + md.event_work); + dm_table_event(rs->ti->table); +} + +/* + * Construct a RAID4/5/6 mapping: + * Args: + * <raid_type> <#raid_params> <raid_params> \ + * <#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> } + * + * ** metadata devices are not supported yet, use '-' instead ** + * + * <raid_params> varies by <raid_type>. See 'parse_raid_params' for + * details on possible <raid_params>. + */ +static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv) +{ + char *err = NULL; + int errnum = -EINVAL; + struct raid_type *rt; + unsigned long num_raid_params, num_raid_devs; + struct raid_set *rs = NULL; + + /* Must have at least <raid_type> <#raid_params> */ + err = "Too few arguments"; + if (argc < 2) + goto err; + + /* raid type */ + err = "Cannot find raid_type"; + rt = get_raid_type(argv[0]); + if (!rt) + goto err; + argc--; argv++; + + /* number of RAID parameters */ + err = "Cannot understand number of RAID parameters"; + if (strict_strtoul(argv[0], 10, &num_raid_params) < 0) + goto err; + argc--; argv++; + + /* Skip over RAID params for now and find out # of devices */ + err = "Arguments do not agree with counts given"; + if (num_raid_params + 1 > argc) + goto err; + + err = "Bad number of raid devices"; + if (strict_strtol(argv[num_raid_params], 10, &num_raid_devs) < 0) + goto err; + + rs = context_alloc(ti, rt, num_raid_devs); + if (IS_ERR(rs)) + return PTR_ERR(rs); + + errnum = parse_raid_params(rs, argv, num_raid_params); + if (errnum) { + err = ti->error; + goto err; + } + errnum = -EINVAL; + + argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */ + argv += num_raid_params + 1; + + err = "Supplied RAID devices does not match the count given"; + if (argc != (num_raid_devs * 2)) + goto err; + + errnum = dev_parms(rs, argv); + if (errnum) { + err = ti->error; + goto err; + } + + INIT_WORK(&rs->md.event_work, do_table_event); + ti->split_io = rs->md.chunk_sectors; + ti->private = rs; + + mutex_lock(&rs->md.reconfig_mutex); + err = "Fail to run raid array"; + errnum = md_run(&rs->md); + rs->md.in_sync = 0; /* Assume already marked dirty */ + mutex_unlock(&rs->md.reconfig_mutex); + + if (!errnum) + return 0; + +err: + if (rs) + context_free(rs); + ti->error = err; + return errnum; +} + +static void raid_dtr(struct dm_target *ti) +{ + struct raid_set *rs = ti->private; + + md_stop(&rs->md); + context_free(rs); +} + +static int raid_map(struct dm_target *ti, struct bio *bio, + union map_info *map_context) +{ + struct raid_set *rs = ti->private; + mddev_t *mddev = &rs->md; + + mddev->pers->make_request(mddev, bio); + return DM_MAPIO_SUBMITTED; +} + +static int raid_status(struct dm_target *ti, status_type_t type, + char *result, unsigned maxlen) +{ + struct raid_set *rs = ti->private; + struct raid5_private_data *conf = rs->md.private; + int sz = 0; + int rbcnt; + int i; + sector_t sync; + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%d ", rs->md.raid_disks); + for (i = 0; i < rs->md.raid_disks; i++) { + if (rs->dev[i].data_dev) + DMEMIT("%s ", rs->dev[i].data_dev->name); + else + DMEMIT("- "); + } + for (i = 0; i < rs->md.raid_disks; i++) { + if (test_bit(Faulty, &rs->dev[i].rdev.flags)) + DMEMIT("D"); + else if (test_bit(In_sync, &rs->dev[i].rdev.flags)) + DMEMIT("A"); + else + DMEMIT("Ai"); + } + DMEMIT(" %u ", conf->max_nr_stripes); + if (test_bit(MD_RECOVERY_RUNNING, &rs->md.recovery)) + sync = rs->md.curr_resync_completed; + else + sync = rs->md.recovery_cp; + if (sync > rs->md.resync_max_sectors) + sync = rs->md.resync_max_sectors; + DMEMIT("%llu/%llu ", + (unsigned long long) sync, + (unsigned long long) rs->md.resync_max_sectors); + + break; + case STATUSTYPE_TABLE: + /* The string you would use to construct this array */ + DMEMIT("%s ", rs->raid_type->name); + DMEMIT("1 %u ", rs->md.chunk_sectors); + + /* Print 1 or 2 rebuild_dev numbers */ + rbcnt = 0; + for (i = 0; i < rs->md.raid_disks; i++) + if (rs->dev[i].data_dev && + !test_bit(In_sync, &rs->dev[i].rdev.flags) && + rbcnt < rs->raid_type->parity_devs) { + DMEMIT("%u ", i); + rbcnt++; + } + while (rbcnt < rs->raid_type->parity_devs) { + DMEMIT("-1 "); + rbcnt++; + } + + DMEMIT("%d ", rs->md.raid_disks); + for (i = 0; i < rs->md.raid_disks; i++) { + DMEMIT("- "); /* metadata device */ + + if (rs->dev[i].data_dev) + DMEMIT("%s ", rs->dev[i].data_dev->name); + else + DMEMIT("- "); + } + break; + } + return 0; +} + +static struct target_type raid_target = { + .name = "raid", + .version = {1, 0, 0}, + .module = THIS_MODULE, + .ctr = raid_ctr, + .dtr = raid_dtr, + .map = raid_map, + .status = raid_status, +}; + +static int __init dm_raid_init(void) +{ + int r = dm_register_target(&raid_target); + + return r; +} + +static void __exit dm_raid_exit(void) +{ + dm_unregister_target(&raid_target); +} + +module_init(dm_raid_init); +module_exit(dm_raid_exit); + +MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("dm-raid4"); +MODULE_ALIAS("dm-raid5"); +MODULE_ALIAS("dm-raid6"); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel