584 lines
15 KiB
C
584 lines
15 KiB
C
/*
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* multipath.c : Multiple Devices driver for Linux
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*
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* Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
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*
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* Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
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*
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* MULTIPATH management functions.
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*
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* derived from raid1.c.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* You should have received a copy of the GNU General Public License
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* (for example /usr/src/linux/COPYING); if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/raid/multipath.h>
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#include <linux/buffer_head.h>
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#include <asm/atomic.h>
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#define MAJOR_NR MD_MAJOR
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#define MD_DRIVER
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#define MD_PERSONALITY
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#define MAX_WORK_PER_DISK 128
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#define NR_RESERVED_BUFS 32
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static void *mp_pool_alloc(gfp_t gfp_flags, void *data)
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{
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struct multipath_bh *mpb;
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mpb = kzalloc(sizeof(*mpb), gfp_flags);
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return mpb;
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}
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static void mp_pool_free(void *mpb, void *data)
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{
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kfree(mpb);
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}
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static int multipath_map (multipath_conf_t *conf)
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{
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int i, disks = conf->raid_disks;
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/*
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* Later we do read balancing on the read side
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* now we use the first available disk.
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*/
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rcu_read_lock();
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for (i = 0; i < disks; i++) {
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mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
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if (rdev && test_bit(In_sync, &rdev->flags)) {
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atomic_inc(&rdev->nr_pending);
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rcu_read_unlock();
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return i;
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}
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}
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rcu_read_unlock();
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printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
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return (-1);
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}
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static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
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{
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unsigned long flags;
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mddev_t *mddev = mp_bh->mddev;
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multipath_conf_t *conf = mddev_to_conf(mddev);
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spin_lock_irqsave(&conf->device_lock, flags);
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list_add(&mp_bh->retry_list, &conf->retry_list);
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spin_unlock_irqrestore(&conf->device_lock, flags);
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md_wakeup_thread(mddev->thread);
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}
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/*
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* multipath_end_bh_io() is called when we have finished servicing a multipathed
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* operation and are ready to return a success/failure code to the buffer
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* cache layer.
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*/
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static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
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{
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struct bio *bio = mp_bh->master_bio;
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multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
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bio_endio(bio, bio->bi_size, err);
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mempool_free(mp_bh, conf->pool);
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}
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static int multipath_end_request(struct bio *bio, unsigned int bytes_done,
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int error)
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{
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int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
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struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private);
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multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
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mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
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if (bio->bi_size)
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return 1;
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if (uptodate)
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multipath_end_bh_io(mp_bh, 0);
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else if (!bio_rw_ahead(bio)) {
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/*
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* oops, IO error:
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*/
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char b[BDEVNAME_SIZE];
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md_error (mp_bh->mddev, rdev);
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printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
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bdevname(rdev->bdev,b),
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(unsigned long long)bio->bi_sector);
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multipath_reschedule_retry(mp_bh);
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} else
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multipath_end_bh_io(mp_bh, error);
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rdev_dec_pending(rdev, conf->mddev);
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return 0;
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}
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static void unplug_slaves(mddev_t *mddev)
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{
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multipath_conf_t *conf = mddev_to_conf(mddev);
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int i;
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rcu_read_lock();
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for (i=0; i<mddev->raid_disks; i++) {
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mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
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if (rdev && !test_bit(Faulty, &rdev->flags)
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&& atomic_read(&rdev->nr_pending)) {
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request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
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atomic_inc(&rdev->nr_pending);
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rcu_read_unlock();
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if (r_queue->unplug_fn)
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r_queue->unplug_fn(r_queue);
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rdev_dec_pending(rdev, mddev);
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rcu_read_lock();
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}
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}
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rcu_read_unlock();
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}
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static void multipath_unplug(request_queue_t *q)
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{
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unplug_slaves(q->queuedata);
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}
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static int multipath_make_request (request_queue_t *q, struct bio * bio)
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{
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mddev_t *mddev = q->queuedata;
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multipath_conf_t *conf = mddev_to_conf(mddev);
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struct multipath_bh * mp_bh;
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struct multipath_info *multipath;
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const int rw = bio_data_dir(bio);
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if (unlikely(bio_barrier(bio))) {
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bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
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return 0;
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}
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mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
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mp_bh->master_bio = bio;
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mp_bh->mddev = mddev;
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disk_stat_inc(mddev->gendisk, ios[rw]);
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disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
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mp_bh->path = multipath_map(conf);
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if (mp_bh->path < 0) {
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bio_endio(bio, bio->bi_size, -EIO);
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mempool_free(mp_bh, conf->pool);
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return 0;
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}
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multipath = conf->multipaths + mp_bh->path;
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mp_bh->bio = *bio;
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mp_bh->bio.bi_sector += multipath->rdev->data_offset;
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mp_bh->bio.bi_bdev = multipath->rdev->bdev;
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mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
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mp_bh->bio.bi_end_io = multipath_end_request;
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mp_bh->bio.bi_private = mp_bh;
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generic_make_request(&mp_bh->bio);
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return 0;
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}
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static void multipath_status (struct seq_file *seq, mddev_t *mddev)
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{
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multipath_conf_t *conf = mddev_to_conf(mddev);
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int i;
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seq_printf (seq, " [%d/%d] [", conf->raid_disks,
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conf->working_disks);
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for (i = 0; i < conf->raid_disks; i++)
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seq_printf (seq, "%s",
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conf->multipaths[i].rdev &&
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test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
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seq_printf (seq, "]");
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}
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static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk,
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sector_t *error_sector)
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{
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mddev_t *mddev = q->queuedata;
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multipath_conf_t *conf = mddev_to_conf(mddev);
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int i, ret = 0;
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rcu_read_lock();
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for (i=0; i<mddev->raid_disks && ret == 0; i++) {
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mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);
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if (rdev && !test_bit(Faulty, &rdev->flags)) {
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struct block_device *bdev = rdev->bdev;
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request_queue_t *r_queue = bdev_get_queue(bdev);
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if (!r_queue->issue_flush_fn)
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ret = -EOPNOTSUPP;
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else {
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atomic_inc(&rdev->nr_pending);
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rcu_read_unlock();
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ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
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error_sector);
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rdev_dec_pending(rdev, mddev);
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rcu_read_lock();
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}
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}
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}
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rcu_read_unlock();
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return ret;
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}
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/*
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* Careful, this can execute in IRQ contexts as well!
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*/
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static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
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{
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multipath_conf_t *conf = mddev_to_conf(mddev);
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if (conf->working_disks <= 1) {
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/*
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* Uh oh, we can do nothing if this is our last path, but
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* first check if this is a queued request for a device
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* which has just failed.
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*/
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printk(KERN_ALERT
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"multipath: only one IO path left and IO error.\n");
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/* leave it active... it's all we have */
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} else {
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/*
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* Mark disk as unusable
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*/
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if (!test_bit(Faulty, &rdev->flags)) {
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char b[BDEVNAME_SIZE];
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clear_bit(In_sync, &rdev->flags);
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set_bit(Faulty, &rdev->flags);
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mddev->sb_dirty = 1;
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conf->working_disks--;
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printk(KERN_ALERT "multipath: IO failure on %s,"
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" disabling IO path. \n Operation continuing"
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" on %d IO paths.\n",
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bdevname (rdev->bdev,b),
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conf->working_disks);
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}
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}
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}
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static void print_multipath_conf (multipath_conf_t *conf)
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{
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int i;
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struct multipath_info *tmp;
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printk("MULTIPATH conf printout:\n");
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if (!conf) {
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printk("(conf==NULL)\n");
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return;
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}
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printk(" --- wd:%d rd:%d\n", conf->working_disks,
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conf->raid_disks);
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for (i = 0; i < conf->raid_disks; i++) {
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char b[BDEVNAME_SIZE];
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tmp = conf->multipaths + i;
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if (tmp->rdev)
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printk(" disk%d, o:%d, dev:%s\n",
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i,!test_bit(Faulty, &tmp->rdev->flags),
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bdevname(tmp->rdev->bdev,b));
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}
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}
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static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
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{
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multipath_conf_t *conf = mddev->private;
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struct request_queue *q;
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int found = 0;
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int path;
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struct multipath_info *p;
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print_multipath_conf(conf);
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for (path=0; path<mddev->raid_disks; path++)
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if ((p=conf->multipaths+path)->rdev == NULL) {
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q = rdev->bdev->bd_disk->queue;
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blk_queue_stack_limits(mddev->queue, q);
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/* as we don't honour merge_bvec_fn, we must never risk
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* violating it, so limit ->max_sector to one PAGE, as
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* a one page request is never in violation.
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* (Note: it is very unlikely that a device with
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* merge_bvec_fn will be involved in multipath.)
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*/
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if (q->merge_bvec_fn &&
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mddev->queue->max_sectors > (PAGE_SIZE>>9))
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blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
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conf->working_disks++;
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rdev->raid_disk = path;
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set_bit(In_sync, &rdev->flags);
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rcu_assign_pointer(p->rdev, rdev);
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found = 1;
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}
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print_multipath_conf(conf);
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return found;
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}
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static int multipath_remove_disk(mddev_t *mddev, int number)
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{
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multipath_conf_t *conf = mddev->private;
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int err = 0;
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mdk_rdev_t *rdev;
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struct multipath_info *p = conf->multipaths + number;
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print_multipath_conf(conf);
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rdev = p->rdev;
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if (rdev) {
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if (test_bit(In_sync, &rdev->flags) ||
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atomic_read(&rdev->nr_pending)) {
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printk(KERN_ERR "hot-remove-disk, slot %d is identified" " but is still operational!\n", number);
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err = -EBUSY;
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goto abort;
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}
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p->rdev = NULL;
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synchronize_rcu();
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if (atomic_read(&rdev->nr_pending)) {
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/* lost the race, try later */
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err = -EBUSY;
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p->rdev = rdev;
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}
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}
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abort:
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print_multipath_conf(conf);
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return err;
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}
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/*
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* This is a kernel thread which:
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*
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* 1. Retries failed read operations on working multipaths.
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* 2. Updates the raid superblock when problems encounter.
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* 3. Performs writes following reads for array syncronising.
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*/
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static void multipathd (mddev_t *mddev)
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{
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struct multipath_bh *mp_bh;
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struct bio *bio;
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unsigned long flags;
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multipath_conf_t *conf = mddev_to_conf(mddev);
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struct list_head *head = &conf->retry_list;
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md_check_recovery(mddev);
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for (;;) {
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char b[BDEVNAME_SIZE];
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spin_lock_irqsave(&conf->device_lock, flags);
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if (list_empty(head))
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break;
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mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
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list_del(head->prev);
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spin_unlock_irqrestore(&conf->device_lock, flags);
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bio = &mp_bh->bio;
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bio->bi_sector = mp_bh->master_bio->bi_sector;
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if ((mp_bh->path = multipath_map (conf))<0) {
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printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
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" error for block %llu\n",
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bdevname(bio->bi_bdev,b),
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(unsigned long long)bio->bi_sector);
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multipath_end_bh_io(mp_bh, -EIO);
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} else {
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printk(KERN_ERR "multipath: %s: redirecting sector %llu"
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" to another IO path\n",
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bdevname(bio->bi_bdev,b),
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(unsigned long long)bio->bi_sector);
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*bio = *(mp_bh->master_bio);
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bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
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bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
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bio->bi_rw |= (1 << BIO_RW_FAILFAST);
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bio->bi_end_io = multipath_end_request;
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bio->bi_private = mp_bh;
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generic_make_request(bio);
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}
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}
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spin_unlock_irqrestore(&conf->device_lock, flags);
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}
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|
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static int multipath_run (mddev_t *mddev)
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{
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multipath_conf_t *conf;
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int disk_idx;
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struct multipath_info *disk;
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mdk_rdev_t *rdev;
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struct list_head *tmp;
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|
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if (mddev->level != LEVEL_MULTIPATH) {
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printk("multipath: %s: raid level not set to multipath IO (%d)\n",
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mdname(mddev), mddev->level);
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goto out;
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}
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/*
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* copy the already verified devices into our private MULTIPATH
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* bookkeeping area. [whatever we allocate in multipath_run(),
|
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* should be freed in multipath_stop()]
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*/
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|
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conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL);
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mddev->private = conf;
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if (!conf) {
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printk(KERN_ERR
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"multipath: couldn't allocate memory for %s\n",
|
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mdname(mddev));
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goto out;
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}
|
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|
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conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
|
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GFP_KERNEL);
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if (!conf->multipaths) {
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printk(KERN_ERR
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"multipath: couldn't allocate memory for %s\n",
|
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mdname(mddev));
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goto out_free_conf;
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}
|
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conf->working_disks = 0;
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ITERATE_RDEV(mddev,rdev,tmp) {
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disk_idx = rdev->raid_disk;
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if (disk_idx < 0 ||
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disk_idx >= mddev->raid_disks)
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continue;
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|
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disk = conf->multipaths + disk_idx;
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disk->rdev = rdev;
|
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|
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blk_queue_stack_limits(mddev->queue,
|
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rdev->bdev->bd_disk->queue);
|
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/* as we don't honour merge_bvec_fn, we must never risk
|
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* violating it, not that we ever expect a device with
|
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* a merge_bvec_fn to be involved in multipath */
|
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if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
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mddev->queue->max_sectors > (PAGE_SIZE>>9))
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blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
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|
|
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if (!test_bit(Faulty, &rdev->flags))
|
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conf->working_disks++;
|
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}
|
|
|
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conf->raid_disks = mddev->raid_disks;
|
|
mddev->sb_dirty = 1;
|
|
conf->mddev = mddev;
|
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spin_lock_init(&conf->device_lock);
|
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INIT_LIST_HEAD(&conf->retry_list);
|
|
|
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if (!conf->working_disks) {
|
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printk(KERN_ERR "multipath: no operational IO paths for %s\n",
|
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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 struct mdk_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,
|
|
};
|
|
|
|
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_ALIAS("md-personality-7"); /* MULTIPATH */
|
|
MODULE_ALIAS("md-multipath");
|
|
MODULE_ALIAS("md-level--4");
|