585 строки
14 KiB
C
585 строки
14 KiB
C
/*
|
|
* multipath.c : Multiple Devices driver for Linux
|
|
*
|
|
* Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
|
|
*
|
|
* Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
|
|
*
|
|
* MULTIPATH management functions.
|
|
*
|
|
* derived from raid1.c.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
* any later version.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* (for example /usr/src/linux/COPYING); if not, write to the Free
|
|
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/raid/multipath.h>
|
|
#include <linux/buffer_head.h>
|
|
#include <asm/atomic.h>
|
|
|
|
#define MAJOR_NR MD_MAJOR
|
|
#define MD_DRIVER
|
|
#define MD_PERSONALITY
|
|
|
|
#define MAX_WORK_PER_DISK 128
|
|
|
|
#define NR_RESERVED_BUFS 32
|
|
|
|
|
|
static mdk_personality_t multipath_personality;
|
|
|
|
|
|
static void *mp_pool_alloc(unsigned int __nocast gfp_flags, void *data)
|
|
{
|
|
struct multipath_bh *mpb;
|
|
mpb = kmalloc(sizeof(*mpb), gfp_flags);
|
|
if (mpb)
|
|
memset(mpb, 0, sizeof(*mpb));
|
|
return mpb;
|
|
}
|
|
|
|
static void mp_pool_free(void *mpb, void *data)
|
|
{
|
|
kfree(mpb);
|
|
}
|
|
|
|
static int multipath_map (multipath_conf_t *conf)
|
|
{
|
|
int i, disks = conf->raid_disks;
|
|
|
|
/*
|
|
* Later we do read balancing on the read side
|
|
* now we use the first available disk.
|
|
*/
|
|
|
|
rcu_read_lock();
|
|
for (i = 0; i < disks; i++) {
|
|
mdk_rdev_t *rdev = conf->multipaths[i].rdev;
|
|
if (rdev && rdev->in_sync) {
|
|
atomic_inc(&rdev->nr_pending);
|
|
rcu_read_unlock();
|
|
return i;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
|
|
return (-1);
|
|
}
|
|
|
|
static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
|
|
{
|
|
unsigned long flags;
|
|
mddev_t *mddev = mp_bh->mddev;
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
|
|
spin_lock_irqsave(&conf->device_lock, flags);
|
|
list_add(&mp_bh->retry_list, &conf->retry_list);
|
|
spin_unlock_irqrestore(&conf->device_lock, flags);
|
|
md_wakeup_thread(mddev->thread);
|
|
}
|
|
|
|
|
|
/*
|
|
* multipath_end_bh_io() is called when we have finished servicing a multipathed
|
|
* operation and are ready to return a success/failure code to the buffer
|
|
* cache layer.
|
|
*/
|
|
static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
|
|
{
|
|
struct bio *bio = mp_bh->master_bio;
|
|
multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
|
|
|
|
bio_endio(bio, bio->bi_size, err);
|
|
mempool_free(mp_bh, conf->pool);
|
|
}
|
|
|
|
static int multipath_end_request(struct bio *bio, unsigned int bytes_done,
|
|
int error)
|
|
{
|
|
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
|
|
struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private);
|
|
multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
|
|
mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
|
|
|
|
if (bio->bi_size)
|
|
return 1;
|
|
|
|
if (uptodate)
|
|
multipath_end_bh_io(mp_bh, 0);
|
|
else if (!bio_rw_ahead(bio)) {
|
|
/*
|
|
* oops, IO error:
|
|
*/
|
|
char b[BDEVNAME_SIZE];
|
|
md_error (mp_bh->mddev, rdev);
|
|
printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
|
|
bdevname(rdev->bdev,b),
|
|
(unsigned long long)bio->bi_sector);
|
|
multipath_reschedule_retry(mp_bh);
|
|
} else
|
|
multipath_end_bh_io(mp_bh, error);
|
|
rdev_dec_pending(rdev, conf->mddev);
|
|
return 0;
|
|
}
|
|
|
|
static void unplug_slaves(mddev_t *mddev)
|
|
{
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
int i;
|
|
|
|
rcu_read_lock();
|
|
for (i=0; i<mddev->raid_disks; i++) {
|
|
mdk_rdev_t *rdev = conf->multipaths[i].rdev;
|
|
if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
|
|
request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
|
|
|
|
atomic_inc(&rdev->nr_pending);
|
|
rcu_read_unlock();
|
|
|
|
if (r_queue->unplug_fn)
|
|
r_queue->unplug_fn(r_queue);
|
|
|
|
rdev_dec_pending(rdev, mddev);
|
|
rcu_read_lock();
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void multipath_unplug(request_queue_t *q)
|
|
{
|
|
unplug_slaves(q->queuedata);
|
|
}
|
|
|
|
|
|
static int multipath_make_request (request_queue_t *q, struct bio * bio)
|
|
{
|
|
mddev_t *mddev = q->queuedata;
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
struct multipath_bh * mp_bh;
|
|
struct multipath_info *multipath;
|
|
|
|
mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
|
|
|
|
mp_bh->master_bio = bio;
|
|
mp_bh->mddev = mddev;
|
|
|
|
if (bio_data_dir(bio)==WRITE) {
|
|
disk_stat_inc(mddev->gendisk, writes);
|
|
disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
|
|
} else {
|
|
disk_stat_inc(mddev->gendisk, reads);
|
|
disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
|
|
}
|
|
|
|
mp_bh->path = multipath_map(conf);
|
|
if (mp_bh->path < 0) {
|
|
bio_endio(bio, bio->bi_size, -EIO);
|
|
mempool_free(mp_bh, conf->pool);
|
|
return 0;
|
|
}
|
|
multipath = conf->multipaths + mp_bh->path;
|
|
|
|
mp_bh->bio = *bio;
|
|
mp_bh->bio.bi_sector += multipath->rdev->data_offset;
|
|
mp_bh->bio.bi_bdev = multipath->rdev->bdev;
|
|
mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
|
|
mp_bh->bio.bi_end_io = multipath_end_request;
|
|
mp_bh->bio.bi_private = mp_bh;
|
|
generic_make_request(&mp_bh->bio);
|
|
return 0;
|
|
}
|
|
|
|
static void multipath_status (struct seq_file *seq, mddev_t *mddev)
|
|
{
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
int i;
|
|
|
|
seq_printf (seq, " [%d/%d] [", conf->raid_disks,
|
|
conf->working_disks);
|
|
for (i = 0; i < conf->raid_disks; i++)
|
|
seq_printf (seq, "%s",
|
|
conf->multipaths[i].rdev &&
|
|
conf->multipaths[i].rdev->in_sync ? "U" : "_");
|
|
seq_printf (seq, "]");
|
|
}
|
|
|
|
static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk,
|
|
sector_t *error_sector)
|
|
{
|
|
mddev_t *mddev = q->queuedata;
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
int i, ret = 0;
|
|
|
|
rcu_read_lock();
|
|
for (i=0; i<mddev->raid_disks && ret == 0; i++) {
|
|
mdk_rdev_t *rdev = conf->multipaths[i].rdev;
|
|
if (rdev && !rdev->faulty) {
|
|
struct block_device *bdev = rdev->bdev;
|
|
request_queue_t *r_queue = bdev_get_queue(bdev);
|
|
|
|
if (!r_queue->issue_flush_fn)
|
|
ret = -EOPNOTSUPP;
|
|
else {
|
|
atomic_inc(&rdev->nr_pending);
|
|
rcu_read_unlock();
|
|
ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
|
|
error_sector);
|
|
rdev_dec_pending(rdev, mddev);
|
|
rcu_read_lock();
|
|
}
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Careful, this can execute in IRQ contexts as well!
|
|
*/
|
|
static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
|
|
{
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
|
|
if (conf->working_disks <= 1) {
|
|
/*
|
|
* Uh oh, we can do nothing if this is our last path, but
|
|
* first check if this is a queued request for a device
|
|
* which has just failed.
|
|
*/
|
|
printk(KERN_ALERT
|
|
"multipath: only one IO path left and IO error.\n");
|
|
/* leave it active... it's all we have */
|
|
} else {
|
|
/*
|
|
* Mark disk as unusable
|
|
*/
|
|
if (!rdev->faulty) {
|
|
char b[BDEVNAME_SIZE];
|
|
rdev->in_sync = 0;
|
|
rdev->faulty = 1;
|
|
mddev->sb_dirty = 1;
|
|
conf->working_disks--;
|
|
printk(KERN_ALERT "multipath: IO failure on %s,"
|
|
" disabling IO path. \n Operation continuing"
|
|
" on %d IO paths.\n",
|
|
bdevname (rdev->bdev,b),
|
|
conf->working_disks);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void print_multipath_conf (multipath_conf_t *conf)
|
|
{
|
|
int i;
|
|
struct multipath_info *tmp;
|
|
|
|
printk("MULTIPATH conf printout:\n");
|
|
if (!conf) {
|
|
printk("(conf==NULL)\n");
|
|
return;
|
|
}
|
|
printk(" --- wd:%d rd:%d\n", conf->working_disks,
|
|
conf->raid_disks);
|
|
|
|
for (i = 0; i < conf->raid_disks; i++) {
|
|
char b[BDEVNAME_SIZE];
|
|
tmp = conf->multipaths + i;
|
|
if (tmp->rdev)
|
|
printk(" disk%d, o:%d, dev:%s\n",
|
|
i,!tmp->rdev->faulty,
|
|
bdevname(tmp->rdev->bdev,b));
|
|
}
|
|
}
|
|
|
|
|
|
static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
|
|
{
|
|
multipath_conf_t *conf = mddev->private;
|
|
int found = 0;
|
|
int path;
|
|
struct multipath_info *p;
|
|
|
|
print_multipath_conf(conf);
|
|
|
|
for (path=0; path<mddev->raid_disks; path++)
|
|
if ((p=conf->multipaths+path)->rdev == NULL) {
|
|
blk_queue_stack_limits(mddev->queue,
|
|
rdev->bdev->bd_disk->queue);
|
|
|
|
/* as we don't honour merge_bvec_fn, we must never risk
|
|
* violating it, so limit ->max_sector to one PAGE, as
|
|
* a one page request is never in violation.
|
|
* (Note: it is very unlikely that a device with
|
|
* merge_bvec_fn will be involved in multipath.)
|
|
*/
|
|
if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
|
|
mddev->queue->max_sectors > (PAGE_SIZE>>9))
|
|
blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
|
|
|
|
conf->working_disks++;
|
|
rdev->raid_disk = path;
|
|
rdev->in_sync = 1;
|
|
p->rdev = rdev;
|
|
found = 1;
|
|
}
|
|
|
|
print_multipath_conf(conf);
|
|
return found;
|
|
}
|
|
|
|
static int multipath_remove_disk(mddev_t *mddev, int number)
|
|
{
|
|
multipath_conf_t *conf = mddev->private;
|
|
int err = 0;
|
|
mdk_rdev_t *rdev;
|
|
struct multipath_info *p = conf->multipaths + number;
|
|
|
|
print_multipath_conf(conf);
|
|
|
|
rdev = p->rdev;
|
|
if (rdev) {
|
|
if (rdev->in_sync ||
|
|
atomic_read(&rdev->nr_pending)) {
|
|
printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
|
|
err = -EBUSY;
|
|
goto abort;
|
|
}
|
|
p->rdev = NULL;
|
|
synchronize_rcu();
|
|
if (atomic_read(&rdev->nr_pending)) {
|
|
/* lost the race, try later */
|
|
err = -EBUSY;
|
|
p->rdev = rdev;
|
|
}
|
|
}
|
|
abort:
|
|
|
|
print_multipath_conf(conf);
|
|
return err;
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* This is a kernel thread which:
|
|
*
|
|
* 1. Retries failed read operations on working multipaths.
|
|
* 2. Updates the raid superblock when problems encounter.
|
|
* 3. Performs writes following reads for array syncronising.
|
|
*/
|
|
|
|
static void multipathd (mddev_t *mddev)
|
|
{
|
|
struct multipath_bh *mp_bh;
|
|
struct bio *bio;
|
|
unsigned long flags;
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
struct list_head *head = &conf->retry_list;
|
|
|
|
md_check_recovery(mddev);
|
|
for (;;) {
|
|
char b[BDEVNAME_SIZE];
|
|
spin_lock_irqsave(&conf->device_lock, flags);
|
|
if (list_empty(head))
|
|
break;
|
|
mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
|
|
list_del(head->prev);
|
|
spin_unlock_irqrestore(&conf->device_lock, flags);
|
|
|
|
bio = &mp_bh->bio;
|
|
bio->bi_sector = mp_bh->master_bio->bi_sector;
|
|
|
|
if ((mp_bh->path = multipath_map (conf))<0) {
|
|
printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
|
|
" error for block %llu\n",
|
|
bdevname(bio->bi_bdev,b),
|
|
(unsigned long long)bio->bi_sector);
|
|
multipath_end_bh_io(mp_bh, -EIO);
|
|
} else {
|
|
printk(KERN_ERR "multipath: %s: redirecting sector %llu"
|
|
" to another IO path\n",
|
|
bdevname(bio->bi_bdev,b),
|
|
(unsigned long long)bio->bi_sector);
|
|
*bio = *(mp_bh->master_bio);
|
|
bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
|
|
bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
|
|
bio->bi_rw |= (1 << BIO_RW_FAILFAST);
|
|
bio->bi_end_io = multipath_end_request;
|
|
bio->bi_private = mp_bh;
|
|
generic_make_request(bio);
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&conf->device_lock, flags);
|
|
}
|
|
|
|
static int multipath_run (mddev_t *mddev)
|
|
{
|
|
multipath_conf_t *conf;
|
|
int disk_idx;
|
|
struct multipath_info *disk;
|
|
mdk_rdev_t *rdev;
|
|
struct list_head *tmp;
|
|
|
|
if (mddev->level != LEVEL_MULTIPATH) {
|
|
printk("multipath: %s: raid level not set to multipath IO (%d)\n",
|
|
mdname(mddev), mddev->level);
|
|
goto out;
|
|
}
|
|
/*
|
|
* copy the already verified devices into our private MULTIPATH
|
|
* bookkeeping area. [whatever we allocate in multipath_run(),
|
|
* should be freed in multipath_stop()]
|
|
*/
|
|
|
|
conf = kmalloc(sizeof(multipath_conf_t), GFP_KERNEL);
|
|
mddev->private = conf;
|
|
if (!conf) {
|
|
printk(KERN_ERR
|
|
"multipath: couldn't allocate memory for %s\n",
|
|
mdname(mddev));
|
|
goto out;
|
|
}
|
|
memset(conf, 0, sizeof(*conf));
|
|
|
|
conf->multipaths = kmalloc(sizeof(struct multipath_info)*mddev->raid_disks,
|
|
GFP_KERNEL);
|
|
if (!conf->multipaths) {
|
|
printk(KERN_ERR
|
|
"multipath: couldn't allocate memory for %s\n",
|
|
mdname(mddev));
|
|
goto out_free_conf;
|
|
}
|
|
memset(conf->multipaths, 0, sizeof(struct multipath_info)*mddev->raid_disks);
|
|
|
|
conf->working_disks = 0;
|
|
ITERATE_RDEV(mddev,rdev,tmp) {
|
|
disk_idx = rdev->raid_disk;
|
|
if (disk_idx < 0 ||
|
|
disk_idx >= mddev->raid_disks)
|
|
continue;
|
|
|
|
disk = conf->multipaths + disk_idx;
|
|
disk->rdev = rdev;
|
|
|
|
blk_queue_stack_limits(mddev->queue,
|
|
rdev->bdev->bd_disk->queue);
|
|
/* as we don't honour merge_bvec_fn, we must never risk
|
|
* violating it, not that we ever expect a device with
|
|
* a merge_bvec_fn to be involved in multipath */
|
|
if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
|
|
mddev->queue->max_sectors > (PAGE_SIZE>>9))
|
|
blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
|
|
|
|
if (!rdev->faulty)
|
|
conf->working_disks++;
|
|
}
|
|
|
|
conf->raid_disks = mddev->raid_disks;
|
|
mddev->sb_dirty = 1;
|
|
conf->mddev = mddev;
|
|
spin_lock_init(&conf->device_lock);
|
|
INIT_LIST_HEAD(&conf->retry_list);
|
|
|
|
if (!conf->working_disks) {
|
|
printk(KERN_ERR "multipath: no operational IO paths for %s\n",
|
|
mdname(mddev));
|
|
goto out_free_conf;
|
|
}
|
|
mddev->degraded = conf->raid_disks = conf->working_disks;
|
|
|
|
conf->pool = mempool_create(NR_RESERVED_BUFS,
|
|
mp_pool_alloc, mp_pool_free,
|
|
NULL);
|
|
if (conf->pool == NULL) {
|
|
printk(KERN_ERR
|
|
"multipath: couldn't allocate memory for %s\n",
|
|
mdname(mddev));
|
|
goto out_free_conf;
|
|
}
|
|
|
|
{
|
|
mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
|
|
if (!mddev->thread) {
|
|
printk(KERN_ERR "multipath: couldn't allocate thread"
|
|
" for %s\n", mdname(mddev));
|
|
goto out_free_conf;
|
|
}
|
|
}
|
|
|
|
printk(KERN_INFO
|
|
"multipath: array %s active with %d out of %d IO paths\n",
|
|
mdname(mddev), conf->working_disks, mddev->raid_disks);
|
|
/*
|
|
* Ok, everything is just fine now
|
|
*/
|
|
mddev->array_size = mddev->size;
|
|
|
|
mddev->queue->unplug_fn = multipath_unplug;
|
|
mddev->queue->issue_flush_fn = multipath_issue_flush;
|
|
|
|
return 0;
|
|
|
|
out_free_conf:
|
|
if (conf->pool)
|
|
mempool_destroy(conf->pool);
|
|
kfree(conf->multipaths);
|
|
kfree(conf);
|
|
mddev->private = NULL;
|
|
out:
|
|
return -EIO;
|
|
}
|
|
|
|
|
|
static int multipath_stop (mddev_t *mddev)
|
|
{
|
|
multipath_conf_t *conf = mddev_to_conf(mddev);
|
|
|
|
md_unregister_thread(mddev->thread);
|
|
mddev->thread = NULL;
|
|
blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
|
|
mempool_destroy(conf->pool);
|
|
kfree(conf->multipaths);
|
|
kfree(conf);
|
|
mddev->private = NULL;
|
|
return 0;
|
|
}
|
|
|
|
static mdk_personality_t multipath_personality=
|
|
{
|
|
.name = "multipath",
|
|
.owner = THIS_MODULE,
|
|
.make_request = multipath_make_request,
|
|
.run = multipath_run,
|
|
.stop = multipath_stop,
|
|
.status = multipath_status,
|
|
.error_handler = multipath_error,
|
|
.hot_add_disk = multipath_add_disk,
|
|
.hot_remove_disk= multipath_remove_disk,
|
|
};
|
|
|
|
static int __init multipath_init (void)
|
|
{
|
|
return register_md_personality (MULTIPATH, &multipath_personality);
|
|
}
|
|
|
|
static void __exit multipath_exit (void)
|
|
{
|
|
unregister_md_personality (MULTIPATH);
|
|
}
|
|
|
|
module_init(multipath_init);
|
|
module_exit(multipath_exit);
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
|