v4.19.13 snapshot.
diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c
new file mode 100644
index 0000000..881487d
--- /dev/null
+++ b/drivers/md/md-multipath.c
@@ -0,0 +1,509 @@
+/*
+ * 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 "md-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) &&
+ !test_bit(Faulty, &rdev->flags)) {
+ atomic_inc(&rdev->nr_pending);
+ rcu_read_unlock();
+ return i;
+ }
+ }
+ rcu_read_unlock();
+
+ pr_crit_ratelimited("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, blk_status_t status)
+{
+ struct bio *bio = mp_bh->master_bio;
+ struct mpconf *conf = mp_bh->mddev->private;
+
+ bio->bi_status = status;
+ bio_endio(bio);
+ mempool_free(mp_bh, &conf->pool);
+}
+
+static void multipath_end_request(struct bio *bio)
+{
+ 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 (!bio->bi_status)
+ multipath_end_bh_io(mp_bh, 0);
+ else if (!(bio->bi_opf & REQ_RAHEAD)) {
+ /*
+ * oops, IO error:
+ */
+ char b[BDEVNAME_SIZE];
+ md_error (mp_bh->mddev, rdev);
+ pr_info("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, bio->bi_status);
+ rdev_dec_pending(rdev, conf->mddev);
+}
+
+static bool 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_opf & REQ_PREFLUSH)) {
+ md_flush_request(mddev, bio);
+ return true;
+ }
+
+ 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_io_error(bio);
+ mempool_free(mp_bh, &conf->pool);
+ return true;
+ }
+ multipath = conf->multipaths + mp_bh->path;
+
+ bio_init(&mp_bh->bio, NULL, 0);
+ __bio_clone_fast(&mp_bh->bio, bio);
+
+ mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
+ bio_set_dev(&mp_bh->bio, multipath->rdev->bdev);
+ mp_bh->bio.bi_opf |= REQ_FAILFAST_TRANSPORT;
+ mp_bh->bio.bi_end_io = multipath_end_request;
+ mp_bh->bio.bi_private = mp_bh;
+ mddev_check_writesame(mddev, &mp_bh->bio);
+ mddev_check_write_zeroes(mddev, &mp_bh->bio);
+ generic_make_request(&mp_bh->bio);
+ return true;
+}
+
+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);
+ rcu_read_lock();
+ for (i = 0; i < conf->raid_disks; i++) {
+ struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
+ seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
+ }
+ rcu_read_unlock();
+ seq_putc(seq, ']');
+}
+
+static int multipath_congested(struct mddev *mddev, int bits)
+{
+ struct mpconf *conf = mddev->private;
+ int i, ret = 0;
+
+ 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.
+ */
+ pr_warn("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_SB_CHANGE_DEVS, &mddev->sb_flags);
+ pr_err("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;
+
+ pr_debug("MULTIPATH conf printout:\n");
+ if (!conf) {
+ pr_debug("(conf==NULL)\n");
+ return;
+ }
+ pr_debug(" --- 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)
+ pr_debug(" 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;
+ 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) {
+ disk_stack_limits(mddev->gendisk, rdev->bdev,
+ rdev->data_offset << 9);
+
+ err = md_integrity_add_rdev(rdev, mddev);
+ if (err)
+ break;
+ 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;
+ 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)) {
+ pr_warn("hot-remove-disk, slot %d is identified but is still operational!\n", number);
+ err = -EBUSY;
+ goto abort;
+ }
+ p->rdev = NULL;
+ if (!test_bit(RemoveSynchronized, &rdev->flags)) {
+ 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) {
+ pr_err("multipath: %s: unrecoverable IO read error for block %llu\n",
+ bio_devname(bio, b),
+ (unsigned long long)bio->bi_iter.bi_sector);
+ multipath_end_bh_io(mp_bh, BLK_STS_IOERR);
+ } else {
+ pr_err("multipath: %s: redirecting sector %llu to another IO path\n",
+ bio_devname(bio, 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_set_dev(bio, conf->multipaths[mp_bh->path].rdev->bdev);
+ bio->bi_opf |= 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;
+ int ret;
+
+ if (md_check_no_bitmap(mddev))
+ return -EINVAL;
+
+ if (mddev->level != LEVEL_MULTIPATH) {
+ pr_warn("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_free()]
+ */
+
+ conf = kzalloc(sizeof(struct mpconf), GFP_KERNEL);
+ mddev->private = conf;
+ if (!conf)
+ goto out;
+
+ conf->multipaths = kcalloc(mddev->raid_disks,
+ sizeof(struct multipath_info),
+ GFP_KERNEL);
+ if (!conf->multipaths)
+ 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);
+
+ 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) {
+ pr_warn("multipath: no operational IO paths for %s\n",
+ mdname(mddev));
+ goto out_free_conf;
+ }
+ mddev->degraded = conf->raid_disks - working_disks;
+
+ ret = mempool_init_kmalloc_pool(&conf->pool, NR_RESERVED_BUFS,
+ sizeof(struct multipath_bh));
+ if (ret)
+ goto out_free_conf;
+
+ mddev->thread = md_register_thread(multipathd, mddev,
+ "multipath");
+ if (!mddev->thread)
+ goto out_free_conf;
+
+ pr_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));
+
+ if (md_integrity_register(mddev))
+ goto out_free_conf;
+
+ return 0;
+
+out_free_conf:
+ mempool_exit(&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_exit(&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");