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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>
This commit is contained in:
Jonathan Brassow 2012-07-31 21:44:26 -05:00 committed by NeilBrown
parent bb181e2e48
commit 63f33b8dda
2 changed files with 116 additions and 5 deletions
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26
Documentation/device-mapper/dm-raid.txt
View File

@ -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

95
drivers/md/dm-raid.c
View File

@ -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");