1 files changed, 343 insertions, 0 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
new file mode 100644
index 00000000000..161e9aa8729
--- /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 */