[dm-devel] [PATCH 4 of 9] dm raid seed module
Jonathan Brassow
jbrassow at redhat.com
Thu Nov 18 23:42:51 UTC 2010
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 at suse.de>
RFC-by: Jonathan Brassow <jbrassow at redhat.com>
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 +1,463 @@
+
+/*
+ * 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);
+ DMEMIT("1 core");
+
+ 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");
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