1 files changed, 343 insertions, 0 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
new file mode 100644
index 000000000000..161e9aa87291
--- /dev/null
+++ b/drivers/md/linear.c
@@ -0,0 +1,343 @@
+/*
+   linear.c : Multiple Devices driver for Linux
+              Copyright (C) 1994-96 Marc ZYNGIER
+              <zyngier@ufr-info-p7.ibp.fr> or
+              <maz@gloups.fdn.fr>
+
+   Linear mode management functions.
+
+   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/raid/md.h>
+#include <linux/slab.h>
+#include <linux/raid/linear.h>
+
+#define MAJOR_NR MD_MAJOR
+#define MD_DRIVER
+#define MD_PERSONALITY
+
+/*
+ * find which device holds a particular offset 
+ */
+static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
+{
+        dev_info_t *hash;
+        linear_conf_t *conf = mddev_to_conf(mddev);
+        sector_t block = sector >> 1;
+
+        /*
+         * sector_div(a,b) returns the remainer and sets a to a/b
+         */
+        (void)sector_div(block, conf->smallest->size);
+        hash = conf->hash_table[block];
+
+        while ((sector>>1) >= (hash->size + hash->offset))
+                hash++;
+        return hash;
+}
+
+/**
+ *      linear_mergeable_bvec -- tell bio layer if a two requests can be merged
+ *      @q: request queue
+ *      @bio: the buffer head that's been built up so far
+ *      @biovec: the request that could be merged to it.
+ *
+ *      Return amount of bytes we can take at this offset
+ */
+static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
+{
+        mddev_t *mddev = q->queuedata;
+        dev_info_t *dev0;
+        unsigned long maxsectors, bio_sectors = bio->bi_size >> 9;
+        sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
+
+        dev0 = which_dev(mddev, sector);
+        maxsectors = (dev0->size << 1) - (sector - (dev0->offset<<1));
+
+        if (maxsectors < bio_sectors)
+                maxsectors = 0;
+        else
+                maxsectors -= bio_sectors;
+
+        if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
+                return biovec->bv_len;
+        /* The bytes available at this offset could be really big,
+         * so we cap at 2^31 to avoid overflow */
+        if (maxsectors > (1 << (31-9)))
+                return 1<<31;
+        return maxsectors << 9;
+}
+
+static void linear_unplug(request_queue_t *q)
+{
+        mddev_t *mddev = q->queuedata;
+        linear_conf_t *conf = mddev_to_conf(mddev);
+        int i;
+
+        for (i=0; i < mddev->raid_disks; i++) {
+                request_queue_t *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
+                if (r_queue->unplug_fn)
+                        r_queue->unplug_fn(r_queue);
+        }
+}
+
+static int linear_issue_flush(request_queue_t *q, struct gendisk *disk,
+                              sector_t *error_sector)
+{
+        mddev_t *mddev = q->queuedata;
+        linear_conf_t *conf = mddev_to_conf(mddev);
+        int i, ret = 0;
+
+        for (i=0; i < mddev->raid_disks && ret == 0; i++) {
+                struct block_device *bdev = conf->disks[i].rdev->bdev;
+                request_queue_t *r_queue = bdev_get_queue(bdev);
+
+                if (!r_queue->issue_flush_fn)
+                        ret = -EOPNOTSUPP;
+                else
+                        ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, error_sector);
+        }
+        return ret;
+}
+
+static int linear_run (mddev_t *mddev)
+{
+        linear_conf_t *conf;
+        dev_info_t **table;
+        mdk_rdev_t *rdev;
+        int i, nb_zone, cnt;
+        sector_t start;
+        sector_t curr_offset;
+        struct list_head *tmp;
+
+        conf = kmalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t),
+                        GFP_KERNEL);
+        if (!conf)
+                goto out;
+        memset(conf, 0, sizeof(*conf) + mddev->raid_disks*sizeof(dev_info_t));
+        mddev->private = conf;
+
+        /*
+         * Find the smallest device.
+         */
+
+        conf->smallest = NULL;
+        cnt = 0;
+        mddev->array_size = 0;
+
+        ITERATE_RDEV(mddev,rdev,tmp) {
+                int j = rdev->raid_disk;
+                dev_info_t *disk = conf->disks + j;
+
+                if (j < 0 || j > mddev->raid_disks || disk->rdev) {
+                        printk("linear: disk numbering problem. Aborting!\n");
+                        goto out;
+                }
+
+                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, so limit ->max_sector to one PAGE, as
+                 * a one page request is never in violation.
+                 */
+                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);
+
+                disk->size = rdev->size;
+                mddev->array_size += rdev->size;
+
+                if (!conf->smallest || (disk->size < conf->smallest->size))
+                        conf->smallest = disk;
+                cnt++;
+        }
+        if (cnt != mddev->raid_disks) {
+                printk("linear: not enough drives present. Aborting!\n");
+                goto out;
+        }
+
+        /*
+         * This code was restructured to work around a gcc-2.95.3 internal
+         * compiler error.  Alter it with care.
+         */
+        {
+                sector_t sz;
+                unsigned round;
+                unsigned long base;
+
+                sz = mddev->array_size;
+                base = conf->smallest->size;
+                round = sector_div(sz, base);
+                nb_zone = conf->nr_zones = sz + (round ? 1 : 0);
+        }
+                        
+        conf->hash_table = kmalloc (sizeof (dev_info_t*) * nb_zone,
+                                        GFP_KERNEL);
+        if (!conf->hash_table)
+                goto out;
+
+        /*
+         * Here we generate the linear hash table
+         */
+        table = conf->hash_table;
+        start = 0;
+        curr_offset = 0;
+        for (i = 0; i < cnt; i++) {
+                dev_info_t *disk = conf->disks + i;
+
+                disk->offset = curr_offset;
+                curr_offset += disk->size;
+
+                /* 'curr_offset' is the end of this disk
+                 * 'start' is the start of table
+                 */
+                while (start < curr_offset) {
+                        *table++ = disk;
+                        start += conf->smallest->size;
+                }
+        }
+        if (table-conf->hash_table != nb_zone)
+                BUG();
+
+        blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
+        mddev->queue->unplug_fn = linear_unplug;
+        mddev->queue->issue_flush_fn = linear_issue_flush;
+        return 0;
+
+out:
+        if (conf)
+                kfree(conf);
+        return 1;
+}
+
+static int linear_stop (mddev_t *mddev)
+{
+        linear_conf_t *conf = mddev_to_conf(mddev);
+  
+        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+        kfree(conf->hash_table);
+        kfree(conf);
+
+        return 0;
+}
+
+static int linear_make_request (request_queue_t *q, struct bio *bio)
+{
+        mddev_t *mddev = q->queuedata;
+        dev_info_t *tmp_dev;
+        sector_t block;
+
+        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));
+        }
+
+        tmp_dev = which_dev(mddev, bio->bi_sector);
+        block = bio->bi_sector >> 1;
+    
+        if (unlikely(block >= (tmp_dev->size + tmp_dev->offset)
+                     || block < tmp_dev->offset)) {
+                char b[BDEVNAME_SIZE];
+
+                printk("linear_make_request: Block %llu out of bounds on "
+                        "dev %s size %llu offset %llu\n",
+                        (unsigned long long)block,
+                        bdevname(tmp_dev->rdev->bdev, b),
+                        (unsigned long long)tmp_dev->size,
+                        (unsigned long long)tmp_dev->offset);
+                bio_io_error(bio, bio->bi_size);
+                return 0;
+        }
+        if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
+                     (tmp_dev->offset + tmp_dev->size)<<1)) {
+                /* This bio crosses a device boundary, so we have to
+                 * split it.
+                 */
+                struct bio_pair *bp;
+                bp = bio_split(bio, bio_split_pool, 
+                               (bio->bi_sector + (bio->bi_size >> 9) -
+                                (tmp_dev->offset + tmp_dev->size))<<1);
+                if (linear_make_request(q, &bp->bio1))
+                        generic_make_request(&bp->bio1);
+                if (linear_make_request(q, &bp->bio2))
+                        generic_make_request(&bp->bio2);
+                bio_pair_release(bp);
+                return 0;
+        }
+                    
+        bio->bi_bdev = tmp_dev->rdev->bdev;
+        bio->bi_sector = bio->bi_sector - (tmp_dev->offset << 1) + tmp_dev->rdev->data_offset;
+
+        return 1;
+}
+
+static void linear_status (struct seq_file *seq, mddev_t *mddev)
+{
+
+#undef MD_DEBUG
+#ifdef MD_DEBUG
+        int j;
+        linear_conf_t *conf = mddev_to_conf(mddev);
+        sector_t s = 0;
+  
+        seq_printf(seq, "      ");
+        for (j = 0; j < conf->nr_zones; j++)
+        {
+                char b[BDEVNAME_SIZE];
+                s += conf->smallest_size;
+                seq_printf(seq, "[%s",
+                           bdevname(conf->hash_table[j][0].rdev->bdev,b));
+
+                while (s > conf->hash_table[j][0].offset +
+                           conf->hash_table[j][0].size)
+                        seq_printf(seq, "/%s] ",
+                                   bdevname(conf->hash_table[j][1].rdev->bdev,b));
+                else
+                        seq_printf(seq, "] ");
+        }
+        seq_printf(seq, "\n");
+#endif
+        seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
+}
+
+
+static mdk_personality_t linear_personality=
+{
+        .name           = "linear",
+        .owner          = THIS_MODULE,
+        .make_request   = linear_make_request,
+        .run            = linear_run,
+        .stop           = linear_stop,
+        .status         = linear_status,
+};
+
+static int __init linear_init (void)
+{
+        return register_md_personality (LINEAR, &linear_personality);
+}
+
+static void linear_exit (void)
+{
+        unregister_md_personality (LINEAR);
+}
+
+
+module_init(linear_init);
+module_exit(linear_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("md-personality-1"); /* LINEAR */