linux/drivers/md/raid0.c
David Jeffery cc22b5407e md: raid0: account for split bio in iostat accounting
When a bio is split by md raid0, the newly created bio will not be tracked
by md for I/O accounting. Only the portion of I/O still assigned to the
original bio which was reduced by the split will be accounted for. This
results in md iostat data sometimes showing I/O values far below the actual
amount of data being sent through md.

md_account_bio() needs to be called for all bio generated by the bio split.

A simple example of the issue was generated using a raid0 device on partitions
to the same device. Since all raid0 I/O then goes to one device, it makes it
easy to see a gap between the md device and its sd storage. Reading an lvm
device on top of the md device, the iostat output (some 0 columns and extra
devices removed to make the data more compact) was:

Device             tps    kB_read/s    kB_wrtn/s    kB_dscd/s    kB_read
md2               0.00         0.00         0.00         0.00          0
sde               0.00         0.00         0.00         0.00          0
md2            1364.00    411496.00         0.00         0.00     411496
sde            1734.00    646144.00         0.00         0.00     646144
md2            1699.00    510680.00         0.00         0.00     510680
sde            2155.00    802784.00         0.00         0.00     802784
md2             803.00    241480.00         0.00         0.00     241480
sde            1016.00    377888.00         0.00         0.00     377888
md2               0.00         0.00         0.00         0.00          0
sde               0.00         0.00         0.00         0.00          0

I/O was generated doing large direct I/O reads (12M) with dd to a linear
lvm volume on top of the 4 leg raid0 device.

The md2 reads were showing as roughly 2/3 of the reads to the sde device
containing all of md2's raid partitions. The sum of reads to sde was
1826816 kB, which was the expected amount as it was the amount read by
dd. With the patch, the total reads from md will match the reads from
sde and be consistent with the amount of I/O generated.

Fixes: 10764815ff ("md: add io accounting for raid0 and raid5")
Signed-off-by: David Jeffery <djeffery@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230816181433.13289-1-djeffery@redhat.com
2023-08-17 21:11:31 -07:00

835 lines
22 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
raid0.c : Multiple Devices driver for Linux
Copyright (C) 1994-96 Marc ZYNGIER
<zyngier@ufr-info-p7.ibp.fr> or
<maz@gloups.fdn.fr>
Copyright (C) 1999, 2000 Ingo Molnar, Red Hat
RAID-0 management functions.
*/
#include <linux/blkdev.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <trace/events/block.h>
#include "md.h"
#include "raid0.h"
#include "raid5.h"
static int default_layout = 0;
module_param(default_layout, int, 0644);
#define UNSUPPORTED_MDDEV_FLAGS \
((1L << MD_HAS_JOURNAL) | \
(1L << MD_JOURNAL_CLEAN) | \
(1L << MD_FAILFAST_SUPPORTED) |\
(1L << MD_HAS_PPL) | \
(1L << MD_HAS_MULTIPLE_PPLS))
/*
* inform the user of the raid configuration
*/
static void dump_zones(struct mddev *mddev)
{
int j, k;
sector_t zone_size = 0;
sector_t zone_start = 0;
struct r0conf *conf = mddev->private;
int raid_disks = conf->strip_zone[0].nb_dev;
pr_debug("md: RAID0 configuration for %s - %d zone%s\n",
mdname(mddev),
conf->nr_strip_zones, conf->nr_strip_zones==1?"":"s");
for (j = 0; j < conf->nr_strip_zones; j++) {
char line[200];
int len = 0;
for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
len += scnprintf(line+len, 200-len, "%s%pg", k?"/":"",
conf->devlist[j * raid_disks + k]->bdev);
pr_debug("md: zone%d=[%s]\n", j, line);
zone_size = conf->strip_zone[j].zone_end - zone_start;
pr_debug(" zone-offset=%10lluKB, device-offset=%10lluKB, size=%10lluKB\n",
(unsigned long long)zone_start>>1,
(unsigned long long)conf->strip_zone[j].dev_start>>1,
(unsigned long long)zone_size>>1);
zone_start = conf->strip_zone[j].zone_end;
}
}
static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
{
int i, c, err;
sector_t curr_zone_end, sectors;
struct md_rdev *smallest, *rdev1, *rdev2, *rdev, **dev;
struct strip_zone *zone;
int cnt;
struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
unsigned blksize = 512;
*private_conf = ERR_PTR(-ENOMEM);
if (!conf)
return -ENOMEM;
rdev_for_each(rdev1, mddev) {
pr_debug("md/raid0:%s: looking at %pg\n",
mdname(mddev),
rdev1->bdev);
c = 0;
/* round size to chunk_size */
sectors = rdev1->sectors;
sector_div(sectors, mddev->chunk_sectors);
rdev1->sectors = sectors * mddev->chunk_sectors;
blksize = max(blksize, queue_logical_block_size(
rdev1->bdev->bd_disk->queue));
rdev_for_each(rdev2, mddev) {
pr_debug("md/raid0:%s: comparing %pg(%llu)"
" with %pg(%llu)\n",
mdname(mddev),
rdev1->bdev,
(unsigned long long)rdev1->sectors,
rdev2->bdev,
(unsigned long long)rdev2->sectors);
if (rdev2 == rdev1) {
pr_debug("md/raid0:%s: END\n",
mdname(mddev));
break;
}
if (rdev2->sectors == rdev1->sectors) {
/*
* Not unique, don't count it as a new
* group
*/
pr_debug("md/raid0:%s: EQUAL\n",
mdname(mddev));
c = 1;
break;
}
pr_debug("md/raid0:%s: NOT EQUAL\n",
mdname(mddev));
}
if (!c) {
pr_debug("md/raid0:%s: ==> UNIQUE\n",
mdname(mddev));
conf->nr_strip_zones++;
pr_debug("md/raid0:%s: %d zones\n",
mdname(mddev), conf->nr_strip_zones);
}
}
pr_debug("md/raid0:%s: FINAL %d zones\n",
mdname(mddev), conf->nr_strip_zones);
/*
* now since we have the hard sector sizes, we can make sure
* chunk size is a multiple of that sector size
*/
if ((mddev->chunk_sectors << 9) % blksize) {
pr_warn("md/raid0:%s: chunk_size of %d not multiple of block size %d\n",
mdname(mddev),
mddev->chunk_sectors << 9, blksize);
err = -EINVAL;
goto abort;
}
err = -ENOMEM;
conf->strip_zone = kcalloc(conf->nr_strip_zones,
sizeof(struct strip_zone),
GFP_KERNEL);
if (!conf->strip_zone)
goto abort;
conf->devlist = kzalloc(array3_size(sizeof(struct md_rdev *),
conf->nr_strip_zones,
mddev->raid_disks),
GFP_KERNEL);
if (!conf->devlist)
goto abort;
/* The first zone must contain all devices, so here we check that
* there is a proper alignment of slots to devices and find them all
*/
zone = &conf->strip_zone[0];
cnt = 0;
smallest = NULL;
dev = conf->devlist;
err = -EINVAL;
rdev_for_each(rdev1, mddev) {
int j = rdev1->raid_disk;
if (mddev->level == 10) {
/* taking over a raid10-n2 array */
j /= 2;
rdev1->new_raid_disk = j;
}
if (mddev->level == 1) {
/* taiking over a raid1 array-
* we have only one active disk
*/
j = 0;
rdev1->new_raid_disk = j;
}
if (j < 0) {
pr_warn("md/raid0:%s: remove inactive devices before converting to RAID0\n",
mdname(mddev));
goto abort;
}
if (j >= mddev->raid_disks) {
pr_warn("md/raid0:%s: bad disk number %d - aborting!\n",
mdname(mddev), j);
goto abort;
}
if (dev[j]) {
pr_warn("md/raid0:%s: multiple devices for %d - aborting!\n",
mdname(mddev), j);
goto abort;
}
dev[j] = rdev1;
if (!smallest || (rdev1->sectors < smallest->sectors))
smallest = rdev1;
cnt++;
}
if (cnt != mddev->raid_disks) {
pr_warn("md/raid0:%s: too few disks (%d of %d) - aborting!\n",
mdname(mddev), cnt, mddev->raid_disks);
goto abort;
}
zone->nb_dev = cnt;
zone->zone_end = smallest->sectors * cnt;
curr_zone_end = zone->zone_end;
/* now do the other zones */
for (i = 1; i < conf->nr_strip_zones; i++)
{
int j;
zone = conf->strip_zone + i;
dev = conf->devlist + i * mddev->raid_disks;
pr_debug("md/raid0:%s: zone %d\n", mdname(mddev), i);
zone->dev_start = smallest->sectors;
smallest = NULL;
c = 0;
for (j=0; j<cnt; j++) {
rdev = conf->devlist[j];
if (rdev->sectors <= zone->dev_start) {
pr_debug("md/raid0:%s: checking %pg ... nope\n",
mdname(mddev),
rdev->bdev);
continue;
}
pr_debug("md/raid0:%s: checking %pg ..."
" contained as device %d\n",
mdname(mddev),
rdev->bdev, c);
dev[c] = rdev;
c++;
if (!smallest || rdev->sectors < smallest->sectors) {
smallest = rdev;
pr_debug("md/raid0:%s: (%llu) is smallest!.\n",
mdname(mddev),
(unsigned long long)rdev->sectors);
}
}
zone->nb_dev = c;
sectors = (smallest->sectors - zone->dev_start) * c;
pr_debug("md/raid0:%s: zone->nb_dev: %d, sectors: %llu\n",
mdname(mddev),
zone->nb_dev, (unsigned long long)sectors);
curr_zone_end += sectors;
zone->zone_end = curr_zone_end;
pr_debug("md/raid0:%s: current zone start: %llu\n",
mdname(mddev),
(unsigned long long)smallest->sectors);
}
if (conf->nr_strip_zones == 1 || conf->strip_zone[1].nb_dev == 1) {
conf->layout = RAID0_ORIG_LAYOUT;
} else if (mddev->layout == RAID0_ORIG_LAYOUT ||
mddev->layout == RAID0_ALT_MULTIZONE_LAYOUT) {
conf->layout = mddev->layout;
} else if (default_layout == RAID0_ORIG_LAYOUT ||
default_layout == RAID0_ALT_MULTIZONE_LAYOUT) {
conf->layout = default_layout;
} else {
pr_err("md/raid0:%s: cannot assemble multi-zone RAID0 with default_layout setting\n",
mdname(mddev));
pr_err("md/raid0: please set raid0.default_layout to 1 or 2\n");
err = -EOPNOTSUPP;
goto abort;
}
if (conf->layout == RAID0_ORIG_LAYOUT) {
for (i = 1; i < conf->nr_strip_zones; i++) {
sector_t first_sector = conf->strip_zone[i-1].zone_end;
sector_div(first_sector, mddev->chunk_sectors);
zone = conf->strip_zone + i;
/* disk_shift is first disk index used in the zone */
zone->disk_shift = sector_div(first_sector,
zone->nb_dev);
}
}
pr_debug("md/raid0:%s: done.\n", mdname(mddev));
*private_conf = conf;
return 0;
abort:
kfree(conf->strip_zone);
kfree(conf->devlist);
kfree(conf);
*private_conf = ERR_PTR(err);
return err;
}
/* Find the zone which holds a particular offset
* Update *sectorp to be an offset in that zone
*/
static struct strip_zone *find_zone(struct r0conf *conf,
sector_t *sectorp)
{
int i;
struct strip_zone *z = conf->strip_zone;
sector_t sector = *sectorp;
for (i = 0; i < conf->nr_strip_zones; i++)
if (sector < z[i].zone_end) {
if (i)
*sectorp = sector - z[i-1].zone_end;
return z + i;
}
BUG();
}
/*
* remaps the bio to the target device. we separate two flows.
* power 2 flow and a general flow for the sake of performance
*/
static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
sector_t sector, sector_t *sector_offset)
{
unsigned int sect_in_chunk;
sector_t chunk;
struct r0conf *conf = mddev->private;
int raid_disks = conf->strip_zone[0].nb_dev;
unsigned int chunk_sects = mddev->chunk_sectors;
if (is_power_of_2(chunk_sects)) {
int chunksect_bits = ffz(~chunk_sects);
/* find the sector offset inside the chunk */
sect_in_chunk = sector & (chunk_sects - 1);
sector >>= chunksect_bits;
/* chunk in zone */
chunk = *sector_offset;
/* quotient is the chunk in real device*/
sector_div(chunk, zone->nb_dev << chunksect_bits);
} else{
sect_in_chunk = sector_div(sector, chunk_sects);
chunk = *sector_offset;
sector_div(chunk, chunk_sects * zone->nb_dev);
}
/*
* position the bio over the real device
* real sector = chunk in device + starting of zone
* + the position in the chunk
*/
*sector_offset = (chunk * chunk_sects) + sect_in_chunk;
return conf->devlist[(zone - conf->strip_zone)*raid_disks
+ sector_div(sector, zone->nb_dev)];
}
static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
{
sector_t array_sectors = 0;
struct md_rdev *rdev;
WARN_ONCE(sectors || raid_disks,
"%s does not support generic reshape\n", __func__);
rdev_for_each(rdev, mddev)
array_sectors += (rdev->sectors &
~(sector_t)(mddev->chunk_sectors-1));
return array_sectors;
}
static void free_conf(struct mddev *mddev, struct r0conf *conf)
{
kfree(conf->strip_zone);
kfree(conf->devlist);
kfree(conf);
}
static void raid0_free(struct mddev *mddev, void *priv)
{
struct r0conf *conf = priv;
free_conf(mddev, conf);
}
static int raid0_run(struct mddev *mddev)
{
struct r0conf *conf;
int ret;
if (mddev->chunk_sectors == 0) {
pr_warn("md/raid0:%s: chunk size must be set.\n", mdname(mddev));
return -EINVAL;
}
if (md_check_no_bitmap(mddev))
return -EINVAL;
/* if private is not null, we are here after takeover */
if (mddev->private == NULL) {
ret = create_strip_zones(mddev, &conf);
if (ret < 0)
return ret;
mddev->private = conf;
}
conf = mddev->private;
if (mddev->queue) {
struct md_rdev *rdev;
blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
blk_queue_io_opt(mddev->queue,
(mddev->chunk_sectors << 9) * mddev->raid_disks);
rdev_for_each(rdev, mddev) {
disk_stack_limits(mddev->gendisk, rdev->bdev,
rdev->data_offset << 9);
}
}
/* calculate array device size */
md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));
pr_debug("md/raid0:%s: md_size is %llu sectors.\n",
mdname(mddev),
(unsigned long long)mddev->array_sectors);
dump_zones(mddev);
ret = md_integrity_register(mddev);
if (ret)
free_conf(mddev, conf);
return ret;
}
/*
* Convert disk_index to the disk order in which it is read/written.
* For example, if we have 4 disks, they are numbered 0,1,2,3. If we
* write the disks starting at disk 3, then the read/write order would
* be disk 3, then 0, then 1, and then disk 2 and we want map_disk_shift()
* to map the disks as follows 0,1,2,3 => 1,2,3,0. So disk 0 would map
* to 1, 1 to 2, 2 to 3, and 3 to 0. That way we can compare disks in
* that 'output' space to understand the read/write disk ordering.
*/
static int map_disk_shift(int disk_index, int num_disks, int disk_shift)
{
return ((disk_index + num_disks - disk_shift) % num_disks);
}
static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
{
struct r0conf *conf = mddev->private;
struct strip_zone *zone;
sector_t start = bio->bi_iter.bi_sector;
sector_t end;
unsigned int stripe_size;
sector_t first_stripe_index, last_stripe_index;
sector_t start_disk_offset;
unsigned int start_disk_index;
sector_t end_disk_offset;
unsigned int end_disk_index;
unsigned int disk;
sector_t orig_start, orig_end;
orig_start = start;
zone = find_zone(conf, &start);
if (bio_end_sector(bio) > zone->zone_end) {
struct bio *split = bio_split(bio,
zone->zone_end - bio->bi_iter.bi_sector, GFP_NOIO,
&mddev->bio_set);
bio_chain(split, bio);
submit_bio_noacct(bio);
bio = split;
end = zone->zone_end;
} else
end = bio_end_sector(bio);
orig_end = end;
if (zone != conf->strip_zone)
end = end - zone[-1].zone_end;
/* Now start and end is the offset in zone */
stripe_size = zone->nb_dev * mddev->chunk_sectors;
first_stripe_index = start;
sector_div(first_stripe_index, stripe_size);
last_stripe_index = end;
sector_div(last_stripe_index, stripe_size);
/* In the first zone the original and alternate layouts are the same */
if ((conf->layout == RAID0_ORIG_LAYOUT) && (zone != conf->strip_zone)) {
sector_div(orig_start, mddev->chunk_sectors);
start_disk_index = sector_div(orig_start, zone->nb_dev);
start_disk_index = map_disk_shift(start_disk_index,
zone->nb_dev,
zone->disk_shift);
sector_div(orig_end, mddev->chunk_sectors);
end_disk_index = sector_div(orig_end, zone->nb_dev);
end_disk_index = map_disk_shift(end_disk_index,
zone->nb_dev, zone->disk_shift);
} else {
start_disk_index = (int)(start - first_stripe_index * stripe_size) /
mddev->chunk_sectors;
end_disk_index = (int)(end - last_stripe_index * stripe_size) /
mddev->chunk_sectors;
}
start_disk_offset = ((int)(start - first_stripe_index * stripe_size) %
mddev->chunk_sectors) +
first_stripe_index * mddev->chunk_sectors;
end_disk_offset = ((int)(end - last_stripe_index * stripe_size) %
mddev->chunk_sectors) +
last_stripe_index * mddev->chunk_sectors;
for (disk = 0; disk < zone->nb_dev; disk++) {
sector_t dev_start, dev_end;
struct md_rdev *rdev;
int compare_disk;
compare_disk = map_disk_shift(disk, zone->nb_dev,
zone->disk_shift);
if (compare_disk < start_disk_index)
dev_start = (first_stripe_index + 1) *
mddev->chunk_sectors;
else if (compare_disk > start_disk_index)
dev_start = first_stripe_index * mddev->chunk_sectors;
else
dev_start = start_disk_offset;
if (compare_disk < end_disk_index)
dev_end = (last_stripe_index + 1) * mddev->chunk_sectors;
else if (compare_disk > end_disk_index)
dev_end = last_stripe_index * mddev->chunk_sectors;
else
dev_end = end_disk_offset;
if (dev_end <= dev_start)
continue;
rdev = conf->devlist[(zone - conf->strip_zone) *
conf->strip_zone[0].nb_dev + disk];
md_submit_discard_bio(mddev, rdev, bio,
dev_start + zone->dev_start + rdev->data_offset,
dev_end - dev_start);
}
bio_endio(bio);
}
static void raid0_map_submit_bio(struct mddev *mddev, struct bio *bio)
{
struct r0conf *conf = mddev->private;
struct strip_zone *zone;
struct md_rdev *tmp_dev;
sector_t bio_sector = bio->bi_iter.bi_sector;
sector_t sector = bio_sector;
md_account_bio(mddev, &bio);
zone = find_zone(mddev->private, &sector);
switch (conf->layout) {
case RAID0_ORIG_LAYOUT:
tmp_dev = map_sector(mddev, zone, bio_sector, &sector);
break;
case RAID0_ALT_MULTIZONE_LAYOUT:
tmp_dev = map_sector(mddev, zone, sector, &sector);
break;
default:
WARN(1, "md/raid0:%s: Invalid layout\n", mdname(mddev));
bio_io_error(bio);
return;
}
if (unlikely(is_rdev_broken(tmp_dev))) {
bio_io_error(bio);
md_error(mddev, tmp_dev);
return;
}
bio_set_dev(bio, tmp_dev->bdev);
bio->bi_iter.bi_sector = sector + zone->dev_start +
tmp_dev->data_offset;
if (mddev->gendisk)
trace_block_bio_remap(bio, disk_devt(mddev->gendisk),
bio_sector);
mddev_check_write_zeroes(mddev, bio);
submit_bio_noacct(bio);
}
static bool raid0_make_request(struct mddev *mddev, struct bio *bio)
{
sector_t sector;
unsigned chunk_sects;
unsigned sectors;
if (unlikely(bio->bi_opf & REQ_PREFLUSH)
&& md_flush_request(mddev, bio))
return true;
if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) {
raid0_handle_discard(mddev, bio);
return true;
}
sector = bio->bi_iter.bi_sector;
chunk_sects = mddev->chunk_sectors;
sectors = chunk_sects -
(likely(is_power_of_2(chunk_sects))
? (sector & (chunk_sects-1))
: sector_div(sector, chunk_sects));
if (sectors < bio_sectors(bio)) {
struct bio *split = bio_split(bio, sectors, GFP_NOIO,
&mddev->bio_set);
bio_chain(split, bio);
raid0_map_submit_bio(mddev, bio);
bio = split;
}
raid0_map_submit_bio(mddev, bio);
return true;
}
static void raid0_status(struct seq_file *seq, struct mddev *mddev)
{
seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
return;
}
static void raid0_error(struct mddev *mddev, struct md_rdev *rdev)
{
if (!test_and_set_bit(MD_BROKEN, &mddev->flags)) {
char *md_name = mdname(mddev);
pr_crit("md/raid0%s: Disk failure on %pg detected, failing array.\n",
md_name, rdev->bdev);
}
}
static void *raid0_takeover_raid45(struct mddev *mddev)
{
struct md_rdev *rdev;
struct r0conf *priv_conf;
if (mddev->degraded != 1) {
pr_warn("md/raid0:%s: raid5 must be degraded! Degraded disks: %d\n",
mdname(mddev),
mddev->degraded);
return ERR_PTR(-EINVAL);
}
rdev_for_each(rdev, mddev) {
/* check slot number for a disk */
if (rdev->raid_disk == mddev->raid_disks-1) {
pr_warn("md/raid0:%s: raid5 must have missing parity disk!\n",
mdname(mddev));
return ERR_PTR(-EINVAL);
}
rdev->sectors = mddev->dev_sectors;
}
/* Set new parameters */
mddev->new_level = 0;
mddev->new_layout = 0;
mddev->new_chunk_sectors = mddev->chunk_sectors;
mddev->raid_disks--;
mddev->delta_disks = -1;
/* make sure it will be not marked as dirty */
mddev->recovery_cp = MaxSector;
mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
create_strip_zones(mddev, &priv_conf);
return priv_conf;
}
static void *raid0_takeover_raid10(struct mddev *mddev)
{
struct r0conf *priv_conf;
/* Check layout:
* - far_copies must be 1
* - near_copies must be 2
* - disks number must be even
* - all mirrors must be already degraded
*/
if (mddev->layout != ((1 << 8) + 2)) {
pr_warn("md/raid0:%s:: Raid0 cannot takeover layout: 0x%x\n",
mdname(mddev),
mddev->layout);
return ERR_PTR(-EINVAL);
}
if (mddev->raid_disks & 1) {
pr_warn("md/raid0:%s: Raid0 cannot takeover Raid10 with odd disk number.\n",
mdname(mddev));
return ERR_PTR(-EINVAL);
}
if (mddev->degraded != (mddev->raid_disks>>1)) {
pr_warn("md/raid0:%s: All mirrors must be already degraded!\n",
mdname(mddev));
return ERR_PTR(-EINVAL);
}
/* Set new parameters */
mddev->new_level = 0;
mddev->new_layout = 0;
mddev->new_chunk_sectors = mddev->chunk_sectors;
mddev->delta_disks = - mddev->raid_disks / 2;
mddev->raid_disks += mddev->delta_disks;
mddev->degraded = 0;
/* make sure it will be not marked as dirty */
mddev->recovery_cp = MaxSector;
mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
create_strip_zones(mddev, &priv_conf);
return priv_conf;
}
static void *raid0_takeover_raid1(struct mddev *mddev)
{
struct r0conf *priv_conf;
int chunksect;
/* Check layout:
* - (N - 1) mirror drives must be already faulty
*/
if ((mddev->raid_disks - 1) != mddev->degraded) {
pr_err("md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
mdname(mddev));
return ERR_PTR(-EINVAL);
}
/*
* a raid1 doesn't have the notion of chunk size, so
* figure out the largest suitable size we can use.
*/
chunksect = 64 * 2; /* 64K by default */
/* The array must be an exact multiple of chunksize */
while (chunksect && (mddev->array_sectors & (chunksect - 1)))
chunksect >>= 1;
if ((chunksect << 9) < PAGE_SIZE)
/* array size does not allow a suitable chunk size */
return ERR_PTR(-EINVAL);
/* Set new parameters */
mddev->new_level = 0;
mddev->new_layout = 0;
mddev->new_chunk_sectors = chunksect;
mddev->chunk_sectors = chunksect;
mddev->delta_disks = 1 - mddev->raid_disks;
mddev->raid_disks = 1;
/* make sure it will be not marked as dirty */
mddev->recovery_cp = MaxSector;
mddev_clear_unsupported_flags(mddev, UNSUPPORTED_MDDEV_FLAGS);
create_strip_zones(mddev, &priv_conf);
return priv_conf;
}
static void *raid0_takeover(struct mddev *mddev)
{
/* raid0 can take over:
* raid4 - if all data disks are active.
* raid5 - providing it is Raid4 layout and one disk is faulty
* raid10 - assuming we have all necessary active disks
* raid1 - with (N -1) mirror drives faulty
*/
if (mddev->bitmap) {
pr_warn("md/raid0: %s: cannot takeover array with bitmap\n",
mdname(mddev));
return ERR_PTR(-EBUSY);
}
if (mddev->level == 4)
return raid0_takeover_raid45(mddev);
if (mddev->level == 5) {
if (mddev->layout == ALGORITHM_PARITY_N)
return raid0_takeover_raid45(mddev);
pr_warn("md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
mdname(mddev), ALGORITHM_PARITY_N);
}
if (mddev->level == 10)
return raid0_takeover_raid10(mddev);
if (mddev->level == 1)
return raid0_takeover_raid1(mddev);
pr_warn("Takeover from raid%i to raid0 not supported\n",
mddev->level);
return ERR_PTR(-EINVAL);
}
static void raid0_quiesce(struct mddev *mddev, int quiesce)
{
}
static struct md_personality raid0_personality=
{
.name = "raid0",
.level = 0,
.owner = THIS_MODULE,
.make_request = raid0_make_request,
.run = raid0_run,
.free = raid0_free,
.status = raid0_status,
.size = raid0_size,
.takeover = raid0_takeover,
.quiesce = raid0_quiesce,
.error_handler = raid0_error,
};
static int __init raid0_init (void)
{
return register_md_personality (&raid0_personality);
}
static void raid0_exit (void)
{
unregister_md_personality (&raid0_personality);
}
module_init(raid0_init);
module_exit(raid0_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
MODULE_ALIAS("md-personality-2"); /* RAID0 */
MODULE_ALIAS("md-raid0");
MODULE_ALIAS("md-level-0");