Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 584 insertions, 0 deletions

diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
new file mode 100644
index 000000000000..c9b134cd1532
--- /dev/null
+++ b/drivers/md/multipath.c
@@ -0,0 +1,584 @@
+/*
+ * multipath.c : Multiple Devices driver for Linux
+ *
+ * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
+ *
+ * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
+ *
+ * MULTIPATH management functions.
+ *
+ * derived from raid1.c.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * (for example /usr/src/linux/COPYING); if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/raid/multipath.h>
+#include <linux/buffer_head.h>
+#include <asm/atomic.h>
+
+#define MAJOR_NR MD_MAJOR
+#define MD_DRIVER
+#define MD_PERSONALITY
+
+#define MAX_WORK_PER_DISK 128
+
+#define NR_RESERVED_BUFS        32
+
+
+static mdk_personality_t multipath_personality;
+
+
+static void *mp_pool_alloc(unsigned int __nocast gfp_flags, void *data)
+{
+        struct multipath_bh *mpb;
+        mpb = kmalloc(sizeof(*mpb), gfp_flags);
+        if (mpb) 
+                memset(mpb, 0, sizeof(*mpb));
+        return mpb;
+}
+
+static void mp_pool_free(void *mpb, void *data)
+{
+        kfree(mpb);
+}
+
+static int multipath_map (multipath_conf_t *conf)
+{
+        int i, disks = conf->raid_disks;
+
+        /*
+         * Later we do read balancing on the read side 
+         * now we use the first available disk.
+         */
+
+        rcu_read_lock();
+        for (i = 0; i < disks; i++) {
+                mdk_rdev_t *rdev = conf->multipaths[i].rdev;
+                if (rdev && rdev->in_sync) {
+                        atomic_inc(&rdev->nr_pending);
+                        rcu_read_unlock();
+                        return i;
+                }
+        }
+        rcu_read_unlock();
+
+        printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
+        return (-1);
+}
+
+static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
+{
+        unsigned long flags;
+        mddev_t *mddev = mp_bh->mddev;
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+
+        spin_lock_irqsave(&conf->device_lock, flags);
+        list_add(&mp_bh->retry_list, &conf->retry_list);
+        spin_unlock_irqrestore(&conf->device_lock, flags);
+        md_wakeup_thread(mddev->thread);
+}
+
+
+/*
+ * multipath_end_bh_io() is called when we have finished servicing a multipathed
+ * operation and are ready to return a success/failure code to the buffer
+ * cache layer.
+ */
+static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
+{
+        struct bio *bio = mp_bh->master_bio;
+        multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
+
+        bio_endio(bio, bio->bi_size, err);
+        mempool_free(mp_bh, conf->pool);
+}
+
+int multipath_end_request(struct bio *bio, unsigned int bytes_done, int error)
+{
+        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+        struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private);
+        multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev);
+        mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev;
+
+        if (bio->bi_size)
+                return 1;
+
+        if (uptodate)
+                multipath_end_bh_io(mp_bh, 0);
+        else if (!bio_rw_ahead(bio)) {
+                /*
+                 * oops, IO error:
+                 */
+                char b[BDEVNAME_SIZE];
+                md_error (mp_bh->mddev, rdev);
+                printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n", 
+                       bdevname(rdev->bdev,b), 
+                       (unsigned long long)bio->bi_sector);
+                multipath_reschedule_retry(mp_bh);
+        } else
+                multipath_end_bh_io(mp_bh, error);
+        rdev_dec_pending(rdev, conf->mddev);
+        return 0;
+}
+
+static void unplug_slaves(mddev_t *mddev)
+{
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+        int i;
+
+        rcu_read_lock();
+        for (i=0; i<mddev->raid_disks; i++) {
+                mdk_rdev_t *rdev = conf->multipaths[i].rdev;
+                if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
+                        request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
+
+                        atomic_inc(&rdev->nr_pending);
+                        rcu_read_unlock();
+
+                        if (r_queue->unplug_fn)
+                                r_queue->unplug_fn(r_queue);
+
+                        rdev_dec_pending(rdev, mddev);
+                        rcu_read_lock();
+                }
+        }
+        rcu_read_unlock();
+}
+
+static void multipath_unplug(request_queue_t *q)
+{
+        unplug_slaves(q->queuedata);
+}
+
+
+static int multipath_make_request (request_queue_t *q, struct bio * bio)
+{
+        mddev_t *mddev = q->queuedata;
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+        struct multipath_bh * mp_bh;
+        struct multipath_info *multipath;
+
+        mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
+
+        mp_bh->master_bio = bio;
+        mp_bh->mddev = mddev;
+
+        if (bio_data_dir(bio)==WRITE) {
+                disk_stat_inc(mddev->gendisk, writes);
+                disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));
+        } else {
+                disk_stat_inc(mddev->gendisk, reads);
+                disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bio));
+        }
+
+        mp_bh->path = multipath_map(conf);
+        if (mp_bh->path < 0) {
+                bio_endio(bio, bio->bi_size, -EIO);
+                mempool_free(mp_bh, conf->pool);
+                return 0;
+        }
+        multipath = conf->multipaths + mp_bh->path;
+
+        mp_bh->bio = *bio;
+        mp_bh->bio.bi_sector += multipath->rdev->data_offset;
+        mp_bh->bio.bi_bdev = multipath->rdev->bdev;
+        mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
+        mp_bh->bio.bi_end_io = multipath_end_request;
+        mp_bh->bio.bi_private = mp_bh;
+        generic_make_request(&mp_bh->bio);
+        return 0;
+}
+
+static void multipath_status (struct seq_file *seq, mddev_t *mddev)
+{
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+        int i;
+        
+        seq_printf (seq, " [%d/%d] [", conf->raid_disks,
+                                                 conf->working_disks);
+        for (i = 0; i < conf->raid_disks; i++)
+                seq_printf (seq, "%s",
+                               conf->multipaths[i].rdev && 
+                               conf->multipaths[i].rdev->in_sync ? "U" : "_");
+        seq_printf (seq, "]");
+}
+
+static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk,
+                                 sector_t *error_sector)
+{
+        mddev_t *mddev = q->queuedata;
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+        int i, ret = 0;
+
+        rcu_read_lock();
+        for (i=0; i<mddev->raid_disks && ret == 0; i++) {
+                mdk_rdev_t *rdev = conf->multipaths[i].rdev;
+                if (rdev && !rdev->faulty) {
+                        struct block_device *bdev = rdev->bdev;
+                        request_queue_t *r_queue = bdev_get_queue(bdev);
+
+                        if (!r_queue->issue_flush_fn)
+                                ret = -EOPNOTSUPP;
+                        else {
+                                atomic_inc(&rdev->nr_pending);
+                                rcu_read_unlock();
+                                ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk,
+                                                              error_sector);
+                                rdev_dec_pending(rdev, mddev);
+                                rcu_read_lock();
+                        }
+                }
+        }
+        rcu_read_unlock();
+        return ret;
+}
+
+/*
+ * Careful, this can execute in IRQ contexts as well!
+ */
+static void multipath_error (mddev_t *mddev, mdk_rdev_t *rdev)
+{
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+
+        if (conf->working_disks <= 1) {
+                /*
+                 * Uh oh, we can do nothing if this is our last path, but
+                 * first check if this is a queued request for a device
+                 * which has just failed.
+                 */
+                printk(KERN_ALERT 
+                        "multipath: only one IO path left and IO error.\n");
+                /* leave it active... it's all we have */
+        } else {
+                /*
+                 * Mark disk as unusable
+                 */
+                if (!rdev->faulty) {
+                        char b[BDEVNAME_SIZE];
+                        rdev->in_sync = 0;
+                        rdev->faulty = 1;
+                        mddev->sb_dirty = 1;
+                        conf->working_disks--;
+                        printk(KERN_ALERT "multipath: IO failure on %s,"
+                                " disabling IO path. \n Operation continuing"
+                                " on %d IO paths.\n",
+                                bdevname (rdev->bdev,b),
+                                conf->working_disks);
+                }
+        }
+}
+
+static void print_multipath_conf (multipath_conf_t *conf)
+{
+        int i;
+        struct multipath_info *tmp;
+
+        printk("MULTIPATH conf printout:\n");
+        if (!conf) {
+                printk("(conf==NULL)\n");
+                return;
+        }
+        printk(" --- wd:%d rd:%d\n", conf->working_disks,
+                         conf->raid_disks);
+
+        for (i = 0; i < conf->raid_disks; i++) {
+                char b[BDEVNAME_SIZE];
+                tmp = conf->multipaths + i;
+                if (tmp->rdev)
+                        printk(" disk%d, o:%d, dev:%s\n",
+                                i,!tmp->rdev->faulty,
+                               bdevname(tmp->rdev->bdev,b));
+        }
+}
+
+
+static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+        multipath_conf_t *conf = mddev->private;
+        int found = 0;
+        int path;
+        struct multipath_info *p;
+
+        print_multipath_conf(conf);
+
+        for (path=0; path<mddev->raid_disks; path++) 
+                if ((p=conf->multipaths+path)->rdev == NULL) {
+                        blk_queue_stack_limits(mddev->queue,
+                                               rdev->bdev->bd_disk->queue);
+
+                /* as we don't honour merge_bvec_fn, we must never risk
+                 * violating it, so limit ->max_sector to one PAGE, as
+                 * a one page request is never in violation.
+                 * (Note: it is very unlikely that a device with
+                 * merge_bvec_fn will be involved in multipath.)
+                 */
+                        if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+                            mddev->queue->max_sectors > (PAGE_SIZE>>9))
+                                blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
+
+                        conf->working_disks++;
+                        rdev->raid_disk = path;
+                        rdev->in_sync = 1;
+                        p->rdev = rdev;
+                        found = 1;
+                }
+
+        print_multipath_conf(conf);
+        return found;
+}
+
+static int multipath_remove_disk(mddev_t *mddev, int number)
+{
+        multipath_conf_t *conf = mddev->private;
+        int err = 0;
+        mdk_rdev_t *rdev;
+        struct multipath_info *p = conf->multipaths + number;
+
+        print_multipath_conf(conf);
+
+        rdev = p->rdev;
+        if (rdev) {
+                if (rdev->in_sync ||
+                    atomic_read(&rdev->nr_pending)) {
+                        printk(KERN_ERR "hot-remove-disk, slot %d is identified"                                " but is still operational!\n", number);
+                        err = -EBUSY;
+                        goto abort;
+                }
+                p->rdev = NULL;
+                synchronize_kernel();
+                if (atomic_read(&rdev->nr_pending)) {
+                        /* lost the race, try later */
+                        err = -EBUSY;
+                        p->rdev = rdev;
+                }
+        }
+abort:
+
+        print_multipath_conf(conf);
+        return err;
+}
+
+
+
+/*
+ * This is a kernel thread which:
+ *
+ *      1.      Retries failed read operations on working multipaths.
+ *      2.      Updates the raid superblock when problems encounter.
+ *      3.      Performs writes following reads for array syncronising.
+ */
+
+static void multipathd (mddev_t *mddev)
+{
+        struct multipath_bh *mp_bh;
+        struct bio *bio;
+        unsigned long flags;
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+        struct list_head *head = &conf->retry_list;
+
+        md_check_recovery(mddev);
+        for (;;) {
+                char b[BDEVNAME_SIZE];
+                spin_lock_irqsave(&conf->device_lock, flags);
+                if (list_empty(head))
+                        break;
+                mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
+                list_del(head->prev);
+                spin_unlock_irqrestore(&conf->device_lock, flags);
+
+                bio = &mp_bh->bio;
+                bio->bi_sector = mp_bh->master_bio->bi_sector;
+                
+                if ((mp_bh->path = multipath_map (conf))<0) {
+                        printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
+                                " error for block %llu\n",
+                                bdevname(bio->bi_bdev,b),
+                                (unsigned long long)bio->bi_sector);
+                        multipath_end_bh_io(mp_bh, -EIO);
+                } else {
+                        printk(KERN_ERR "multipath: %s: redirecting sector %llu"
+                                " to another IO path\n",
+                                bdevname(bio->bi_bdev,b),
+                                (unsigned long long)bio->bi_sector);
+                        *bio = *(mp_bh->master_bio);
+                        bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset;
+                        bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
+                        bio->bi_rw |= (1 << BIO_RW_FAILFAST);
+                        bio->bi_end_io = multipath_end_request;
+                        bio->bi_private = mp_bh;
+                        generic_make_request(bio);
+                }
+        }
+        spin_unlock_irqrestore(&conf->device_lock, flags);
+}
+
+static int multipath_run (mddev_t *mddev)
+{
+        multipath_conf_t *conf;
+        int disk_idx;
+        struct multipath_info *disk;
+        mdk_rdev_t *rdev;
+        struct list_head *tmp;
+
+        if (mddev->level != LEVEL_MULTIPATH) {
+                printk("multipath: %s: raid level not set to multipath IO (%d)\n",
+                       mdname(mddev), mddev->level);
+                goto out;
+        }
+        /*
+         * copy the already verified devices into our private MULTIPATH
+         * bookkeeping area. [whatever we allocate in multipath_run(),
+         * should be freed in multipath_stop()]
+         */
+
+        conf = kmalloc(sizeof(multipath_conf_t), GFP_KERNEL);
+        mddev->private = conf;
+        if (!conf) {
+                printk(KERN_ERR 
+                        "multipath: couldn't allocate memory for %s\n",
+                        mdname(mddev));
+                goto out;
+        }
+        memset(conf, 0, sizeof(*conf));
+
+        conf->multipaths = kmalloc(sizeof(struct multipath_info)*mddev->raid_disks,
+                                   GFP_KERNEL);
+        if (!conf->multipaths) {
+                printk(KERN_ERR 
+                        "multipath: couldn't allocate memory for %s\n",
+                        mdname(mddev));
+                goto out_free_conf;
+        }
+        memset(conf->multipaths, 0, sizeof(struct multipath_info)*mddev->raid_disks);
+
+        mddev->queue->unplug_fn = multipath_unplug;
+
+        mddev->queue->issue_flush_fn = multipath_issue_flush;
+
+        conf->working_disks = 0;
+        ITERATE_RDEV(mddev,rdev,tmp) {
+                disk_idx = rdev->raid_disk;
+                if (disk_idx < 0 ||
+                    disk_idx >= mddev->raid_disks)
+                        continue;
+
+                disk = conf->multipaths + disk_idx;
+                disk->rdev = rdev;
+
+                blk_queue_stack_limits(mddev->queue,
+                                       rdev->bdev->bd_disk->queue);
+                /* as we don't honour merge_bvec_fn, we must never risk
+                 * violating it, not that we ever expect a device with
+                 * a merge_bvec_fn to be involved in multipath */
+                if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+                    mddev->queue->max_sectors > (PAGE_SIZE>>9))
+                        blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
+
+                if (!rdev->faulty) 
+                        conf->working_disks++;
+        }
+
+        conf->raid_disks = mddev->raid_disks;
+        mddev->sb_dirty = 1;
+        conf->mddev = mddev;
+        spin_lock_init(&conf->device_lock);
+        INIT_LIST_HEAD(&conf->retry_list);
+
+        if (!conf->working_disks) {
+                printk(KERN_ERR "multipath: no operational IO paths for %s\n",
+                        mdname(mddev));
+                goto out_free_conf;
+        }
+        mddev->degraded = conf->raid_disks = conf->working_disks;
+
+        conf->pool = mempool_create(NR_RESERVED_BUFS,
+                                    mp_pool_alloc, mp_pool_free,
+                                    NULL);
+        if (conf->pool == NULL) {
+                printk(KERN_ERR 
+                        "multipath: couldn't allocate memory for %s\n",
+                        mdname(mddev));
+                goto out_free_conf;
+        }
+
+        {
+                mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath");
+                if (!mddev->thread) {
+                        printk(KERN_ERR "multipath: couldn't allocate thread"
+                                " for %s\n", mdname(mddev));
+                        goto out_free_conf;
+                }
+        }
+
+        printk(KERN_INFO 
+                "multipath: array %s active with %d out of %d IO paths\n",
+                mdname(mddev), conf->working_disks, mddev->raid_disks);
+        /*
+         * Ok, everything is just fine now
+         */
+        mddev->array_size = mddev->size;
+        return 0;
+
+out_free_conf:
+        if (conf->pool)
+                mempool_destroy(conf->pool);
+        if (conf->multipaths)
+                kfree(conf->multipaths);
+        kfree(conf);
+        mddev->private = NULL;
+out:
+        return -EIO;
+}
+
+
+static int multipath_stop (mddev_t *mddev)
+{
+        multipath_conf_t *conf = mddev_to_conf(mddev);
+
+        md_unregister_thread(mddev->thread);
+        mddev->thread = NULL;
+        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+        mempool_destroy(conf->pool);
+        kfree(conf->multipaths);
+        kfree(conf);
+        mddev->private = NULL;
+        return 0;
+}
+
+static mdk_personality_t multipath_personality=
+{
+        .name           = "multipath",
+        .owner          = THIS_MODULE,
+        .make_request   = multipath_make_request,
+        .run            = multipath_run,
+        .stop           = multipath_stop,
+        .status         = multipath_status,
+        .error_handler  = multipath_error,
+        .hot_add_disk   = multipath_add_disk,
+        .hot_remove_disk= multipath_remove_disk,
+};
+
+static int __init multipath_init (void)
+{
+        return register_md_personality (MULTIPATH, &multipath_personality);
+}
+
+static void __exit multipath_exit (void)
+{
+        unregister_md_personality (MULTIPATH);
+}
+
+module_init(multipath_init);
+module_exit(multipath_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("md-personality-7"); /* MULTIPATH */