forked from Minki/linux
4246a0b63b
Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
545 lines
14 KiB
C
545 lines
14 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/blkdev.h>
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#include <linux/module.h>
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#include <linux/raid/md_u.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include "md.h"
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#include "multipath.h"
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#define MAX_WORK_PER_DISK 128
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#define NR_RESERVED_BUFS 32
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static int multipath_map (struct mpconf *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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struct md_rdev *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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struct mddev *mddev = mp_bh->mddev;
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struct mpconf *conf = mddev->private;
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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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struct mpconf *conf = mp_bh->mddev->private;
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bio->bi_error = err;
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bio_endio(bio);
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mempool_free(mp_bh, conf->pool);
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}
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static void multipath_end_request(struct bio *bio)
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{
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struct multipath_bh *mp_bh = bio->bi_private;
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struct mpconf *conf = mp_bh->mddev->private;
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struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev;
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if (!bio->bi_error)
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multipath_end_bh_io(mp_bh, 0);
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else if (!(bio->bi_rw & REQ_RAHEAD)) {
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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_iter.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, bio->bi_error);
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rdev_dec_pending(rdev, conf->mddev);
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}
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static void multipath_make_request(struct mddev *mddev, struct bio * bio)
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{
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struct mpconf *conf = mddev->private;
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struct multipath_bh * mp_bh;
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struct multipath_info *multipath;
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if (unlikely(bio->bi_rw & REQ_FLUSH)) {
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md_flush_request(mddev, bio);
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return;
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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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mp_bh->path = multipath_map(conf);
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if (mp_bh->path < 0) {
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bio_io_error(bio);
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mempool_free(mp_bh, conf->pool);
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return;
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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_iter.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 |= REQ_FAILFAST_TRANSPORT;
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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;
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}
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static void multipath_status (struct seq_file *seq, struct mddev *mddev)
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{
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struct mpconf *conf = mddev->private;
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int i;
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seq_printf (seq, " [%d/%d] [", conf->raid_disks,
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conf->raid_disks - mddev->degraded);
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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_congested(struct mddev *mddev, int bits)
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{
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struct mpconf *conf = mddev->private;
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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 ; i++) {
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struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
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if (rdev && !test_bit(Faulty, &rdev->flags)) {
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struct request_queue *q = bdev_get_queue(rdev->bdev);
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ret |= bdi_congested(&q->backing_dev_info, bits);
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/* Just like multipath_map, we just check the
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* first available device
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*/
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break;
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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 (struct mddev *mddev, struct md_rdev *rdev)
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{
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struct mpconf *conf = mddev->private;
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char b[BDEVNAME_SIZE];
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if (conf->raid_disks - mddev->degraded <= 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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return;
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}
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/*
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* Mark disk as unusable
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*/
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if (test_and_clear_bit(In_sync, &rdev->flags)) {
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unsigned long flags;
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spin_lock_irqsave(&conf->device_lock, flags);
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mddev->degraded++;
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spin_unlock_irqrestore(&conf->device_lock, flags);
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}
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set_bit(Faulty, &rdev->flags);
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set_bit(MD_CHANGE_DEVS, &mddev->flags);
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printk(KERN_ALERT "multipath: IO failure on %s,"
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" disabling IO path.\n"
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"multipath: Operation continuing"
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" on %d IO paths.\n",
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bdevname(rdev->bdev, b),
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conf->raid_disks - mddev->degraded);
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}
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static void print_multipath_conf (struct mpconf *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->raid_disks - conf->mddev->degraded,
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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(struct mddev *mddev, struct md_rdev *rdev)
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{
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struct mpconf *conf = mddev->private;
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struct request_queue *q;
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int err = -EEXIST;
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int path;
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struct multipath_info *p;
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int first = 0;
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int last = mddev->raid_disks - 1;
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if (rdev->raid_disk >= 0)
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first = last = rdev->raid_disk;
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print_multipath_conf(conf);
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for (path = first; path <= last; 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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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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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_segments to one, lying
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* within a single page.
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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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blk_queue_max_segments(mddev->queue, 1);
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blk_queue_segment_boundary(mddev->queue,
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PAGE_CACHE_SIZE - 1);
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}
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spin_lock_irq(&conf->device_lock);
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mddev->degraded--;
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rdev->raid_disk = path;
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set_bit(In_sync, &rdev->flags);
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spin_unlock_irq(&conf->device_lock);
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rcu_assign_pointer(p->rdev, rdev);
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err = 0;
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md_integrity_add_rdev(rdev, mddev);
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break;
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}
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print_multipath_conf(conf);
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return err;
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}
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static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
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{
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struct mpconf *conf = mddev->private;
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int err = 0;
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int number = rdev->raid_disk;
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struct multipath_info *p = conf->multipaths + number;
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print_multipath_conf(conf);
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if (rdev == p->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"
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" 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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goto abort;
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}
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err = md_integrity_register(mddev);
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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(struct md_thread *thread)
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{
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struct mddev *mddev = thread->mddev;
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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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struct mpconf *conf = mddev->private;
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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_iter.bi_sector = mp_bh->master_bio->bi_iter.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_iter.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_iter.bi_sector);
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*bio = *(mp_bh->master_bio);
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bio->bi_iter.bi_sector +=
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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 |= REQ_FAILFAST_TRANSPORT;
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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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static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks)
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{
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WARN_ONCE(sectors || raid_disks,
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"%s does not support generic reshape\n", __func__);
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return mddev->dev_sectors;
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}
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static int multipath_run (struct mddev *mddev)
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{
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struct mpconf *conf;
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int disk_idx;
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struct multipath_info *disk;
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struct md_rdev *rdev;
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int working_disks;
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if (md_check_no_bitmap(mddev))
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return -EINVAL;
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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_free()]
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*/
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conf = kzalloc(sizeof(struct mpconf), 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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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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working_disks = 0;
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rdev_for_each(rdev, mddev) {
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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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disk = conf->multipaths + disk_idx;
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disk->rdev = rdev;
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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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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blk_queue_max_segments(mddev->queue, 1);
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blk_queue_segment_boundary(mddev->queue,
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PAGE_CACHE_SIZE - 1);
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}
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if (!test_bit(Faulty, &rdev->flags))
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working_disks++;
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}
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conf->raid_disks = mddev->raid_disks;
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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 (!working_disks) {
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printk(KERN_ERR "multipath: no operational IO paths 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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mddev->degraded = conf->raid_disks - working_disks;
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conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS,
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sizeof(struct multipath_bh));
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if (conf->pool == NULL) {
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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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{
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mddev->thread = md_register_thread(multipathd, mddev,
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"multipath");
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if (!mddev->thread) {
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printk(KERN_ERR "multipath: couldn't allocate thread"
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" for %s\n", mdname(mddev));
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goto out_free_conf;
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}
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}
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printk(KERN_INFO
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"multipath: array %s active with %d out of %d IO paths\n",
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mdname(mddev), conf->raid_disks - mddev->degraded,
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mddev->raid_disks);
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/*
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* Ok, everything is just fine now
|
|
*/
|
|
md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
|
|
|
|
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 void multipath_free(struct mddev *mddev, void *priv)
|
|
{
|
|
struct mpconf *conf = priv;
|
|
|
|
mempool_destroy(conf->pool);
|
|
kfree(conf->multipaths);
|
|
kfree(conf);
|
|
}
|
|
|
|
static struct md_personality multipath_personality =
|
|
{
|
|
.name = "multipath",
|
|
.level = LEVEL_MULTIPATH,
|
|
.owner = THIS_MODULE,
|
|
.make_request = multipath_make_request,
|
|
.run = multipath_run,
|
|
.free = multipath_free,
|
|
.status = multipath_status,
|
|
.error_handler = multipath_error,
|
|
.hot_add_disk = multipath_add_disk,
|
|
.hot_remove_disk= multipath_remove_disk,
|
|
.size = multipath_size,
|
|
.congested = multipath_congested,
|
|
};
|
|
|
|
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");
|