linux/drivers/md/multipath.c
Kent Overstreet 4f024f3797 block: Abstract out bvec iterator
Immutable biovecs are going to require an explicit iterator. To
implement immutable bvecs, a later patch is going to add a bi_bvec_done
member to this struct; for now, this patch effectively just renames
things.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Boaz Harrosh <bharrosh@panasas.com>
Cc: Benny Halevy <bhalevy@tonian.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Ben Myers <bpm@sgi.com>
Cc: xfs@oss.sgi.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchand@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Peng Tao <tao.peng@emc.com>
Cc: Andy Adamson <andros@netapp.com>
Cc: fanchaoting <fanchaoting@cn.fujitsu.com>
Cc: Jie Liu <jeff.liu@oracle.com>
Cc: Sunil Mushran <sunil.mushran@gmail.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Pankaj Kumar <pankaj.km@samsung.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Mel Gorman <mgorman@suse.de>6
2013-11-23 22:33:47 -08:00

561 lines
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/blkdev.h>
#include <linux/module.h>
#include <linux/raid/md_u.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include "md.h"
#include "multipath.h"
#define MAX_WORK_PER_DISK 128
#define NR_RESERVED_BUFS 32
static int multipath_map (struct mpconf *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++) {
struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
if (rdev && test_bit(In_sync, &rdev->flags)) {
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;
struct mddev *mddev = mp_bh->mddev;
struct mpconf *conf = mddev->private;
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;
struct mpconf *conf = mp_bh->mddev->private;
bio_endio(bio, err);
mempool_free(mp_bh, conf->pool);
}
static void multipath_end_request(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
struct multipath_bh *mp_bh = bio->bi_private;
struct mpconf *conf = mp_bh->mddev->private;
struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev;
if (uptodate)
multipath_end_bh_io(mp_bh, 0);
else if (!(bio->bi_rw & REQ_RAHEAD)) {
/*
* 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_iter.bi_sector);
multipath_reschedule_retry(mp_bh);
} else
multipath_end_bh_io(mp_bh, error);
rdev_dec_pending(rdev, conf->mddev);
}
static void multipath_make_request(struct mddev *mddev, struct bio * bio)
{
struct mpconf *conf = mddev->private;
struct multipath_bh * mp_bh;
struct multipath_info *multipath;
if (unlikely(bio->bi_rw & REQ_FLUSH)) {
md_flush_request(mddev, bio);
return;
}
mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
mp_bh->master_bio = bio;
mp_bh->mddev = mddev;
mp_bh->path = multipath_map(conf);
if (mp_bh->path < 0) {
bio_endio(bio, -EIO);
mempool_free(mp_bh, conf->pool);
return;
}
multipath = conf->multipaths + mp_bh->path;
mp_bh->bio = *bio;
mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
mp_bh->bio.bi_bdev = multipath->rdev->bdev;
mp_bh->bio.bi_rw |= REQ_FAILFAST_TRANSPORT;
mp_bh->bio.bi_end_io = multipath_end_request;
mp_bh->bio.bi_private = mp_bh;
generic_make_request(&mp_bh->bio);
return;
}
static void multipath_status (struct seq_file *seq, struct mddev *mddev)
{
struct mpconf *conf = mddev->private;
int i;
seq_printf (seq, " [%d/%d] [", conf->raid_disks,
conf->raid_disks - mddev->degraded);
for (i = 0; i < conf->raid_disks; i++)
seq_printf (seq, "%s",
conf->multipaths[i].rdev &&
test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
seq_printf (seq, "]");
}
static int multipath_congested(void *data, int bits)
{
struct mddev *mddev = data;
struct mpconf *conf = mddev->private;
int i, ret = 0;
if (mddev_congested(mddev, bits))
return 1;
rcu_read_lock();
for (i = 0; i < mddev->raid_disks ; i++) {
struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
if (rdev && !test_bit(Faulty, &rdev->flags)) {
struct request_queue *q = bdev_get_queue(rdev->bdev);
ret |= bdi_congested(&q->backing_dev_info, bits);
/* Just like multipath_map, we just check the
* first available device
*/
break;
}
}
rcu_read_unlock();
return ret;
}
/*
* Careful, this can execute in IRQ contexts as well!
*/
static void multipath_error (struct mddev *mddev, struct md_rdev *rdev)
{
struct mpconf *conf = mddev->private;
char b[BDEVNAME_SIZE];
if (conf->raid_disks - mddev->degraded <= 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 */
return;
}
/*
* Mark disk as unusable
*/
if (test_and_clear_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
spin_unlock_irqrestore(&conf->device_lock, flags);
}
set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
printk(KERN_ALERT "multipath: IO failure on %s,"
" disabling IO path.\n"
"multipath: Operation continuing"
" on %d IO paths.\n",
bdevname(rdev->bdev, b),
conf->raid_disks - mddev->degraded);
}
static void print_multipath_conf (struct mpconf *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->raid_disks - conf->mddev->degraded,
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,!test_bit(Faulty, &tmp->rdev->flags),
bdevname(tmp->rdev->bdev,b));
}
}
static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
{
struct mpconf *conf = mddev->private;
struct request_queue *q;
int err = -EEXIST;
int path;
struct multipath_info *p;
int first = 0;
int last = mddev->raid_disks - 1;
if (rdev->raid_disk >= 0)
first = last = rdev->raid_disk;
print_multipath_conf(conf);
for (path = first; path <= last; path++)
if ((p=conf->multipaths+path)->rdev == NULL) {
q = rdev->bdev->bd_disk->queue;
disk_stack_limits(mddev->gendisk, rdev->bdev,
rdev->data_offset << 9);
/* as we don't honour merge_bvec_fn, we must never risk
* violating it, so limit ->max_segments to one, lying
* within a single page.
* (Note: it is very unlikely that a device with
* merge_bvec_fn will be involved in multipath.)
*/
if (q->merge_bvec_fn) {
blk_queue_max_segments(mddev->queue, 1);
blk_queue_segment_boundary(mddev->queue,
PAGE_CACHE_SIZE - 1);
}
spin_lock_irq(&conf->device_lock);
mddev->degraded--;
rdev->raid_disk = path;
set_bit(In_sync, &rdev->flags);
spin_unlock_irq(&conf->device_lock);
rcu_assign_pointer(p->rdev, rdev);
err = 0;
md_integrity_add_rdev(rdev, mddev);
break;
}
print_multipath_conf(conf);
return err;
}
static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
{
struct mpconf *conf = mddev->private;
int err = 0;
int number = rdev->raid_disk;
struct multipath_info *p = conf->multipaths + number;
print_multipath_conf(conf);
if (rdev == p->rdev) {
if (test_bit(In_sync, &rdev->flags) ||
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;
goto abort;
}
err = md_integrity_register(mddev);
}
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(struct md_thread *thread)
{
struct mddev *mddev = thread->mddev;
struct multipath_bh *mp_bh;
struct bio *bio;
unsigned long flags;
struct mpconf *conf = mddev->private;
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_iter.bi_sector = mp_bh->master_bio->bi_iter.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_iter.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_iter.bi_sector);
*bio = *(mp_bh->master_bio);
bio->bi_iter.bi_sector +=
conf->multipaths[mp_bh->path].rdev->data_offset;
bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
bio->bi_rw |= REQ_FAILFAST_TRANSPORT;
bio->bi_end_io = multipath_end_request;
bio->bi_private = mp_bh;
generic_make_request(bio);
}
}
spin_unlock_irqrestore(&conf->device_lock, flags);
}
static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks)
{
WARN_ONCE(sectors || raid_disks,
"%s does not support generic reshape\n", __func__);
return mddev->dev_sectors;
}
static int multipath_run (struct mddev *mddev)
{
struct mpconf *conf;
int disk_idx;
struct multipath_info *disk;
struct md_rdev *rdev;
int working_disks;
if (md_check_no_bitmap(mddev))
return -EINVAL;
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 = kzalloc(sizeof(struct mpconf), GFP_KERNEL);
mddev->private = conf;
if (!conf) {
printk(KERN_ERR
"multipath: couldn't allocate memory for %s\n",
mdname(mddev));
goto out;
}
conf->multipaths = kzalloc(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;
}
working_disks = 0;
rdev_for_each(rdev, mddev) {
disk_idx = rdev->raid_disk;
if (disk_idx < 0 ||
disk_idx >= mddev->raid_disks)
continue;
disk = conf->multipaths + disk_idx;
disk->rdev = rdev;
disk_stack_limits(mddev->gendisk, rdev->bdev,
rdev->data_offset << 9);
/* 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) {
blk_queue_max_segments(mddev->queue, 1);
blk_queue_segment_boundary(mddev->queue,
PAGE_CACHE_SIZE - 1);
}
if (!test_bit(Faulty, &rdev->flags))
working_disks++;
}
conf->raid_disks = mddev->raid_disks;
conf->mddev = mddev;
spin_lock_init(&conf->device_lock);
INIT_LIST_HEAD(&conf->retry_list);
if (!working_disks) {
printk(KERN_ERR "multipath: no operational IO paths for %s\n",
mdname(mddev));
goto out_free_conf;
}
mddev->degraded = conf->raid_disks - working_disks;
conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS,
sizeof(struct multipath_bh));
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,
"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->raid_disks - mddev->degraded,
mddev->raid_disks);
/*
* Ok, everything is just fine now
*/
md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
mddev->queue->backing_dev_info.congested_fn = multipath_congested;
mddev->queue->backing_dev_info.congested_data = mddev;
if (md_integrity_register(mddev))
goto out_free_conf;
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 (struct mddev *mddev)
{
struct mpconf *conf = mddev->private;
md_unregister_thread(&mddev->thread);
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 struct md_personality multipath_personality =
{
.name = "multipath",
.level = LEVEL_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,
.size = multipath_size,
};
static int __init multipath_init (void)
{
return register_md_personality (&multipath_personality);
}
static void __exit multipath_exit (void)
{
unregister_md_personality (&multipath_personality);
}
module_init(multipath_init);
module_exit(multipath_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("simple multi-path personality for MD");
MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
MODULE_ALIAS("md-multipath");
MODULE_ALIAS("md-level--4");