1 files changed, 369 insertions, 0 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
new file mode 100644
index 00000000..abfb59a6
--- /dev/null
+++ b/drivers/md/linear.c
@@ -0,0 +1,369 @@
+/*
+   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/blkdev.h>
+#include <linux/raid/md_u.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include "md.h"
+#include "linear.h"
+
+/*
+ * find which device holds a particular offset 
+ */
+static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
+{
+	int lo, mid, hi;
+	linear_conf_t *conf;
+
+	lo = 0;
+	hi = mddev->raid_disks - 1;
+	conf = rcu_dereference(mddev->private);
+
+	/*
+	 * Binary Search
+	 */
+
+	while (hi > lo) {
+
+		mid = (hi + lo) / 2;
+		if (sector < conf->disks[mid].end_sector)
+			hi = mid;
+		else
+			lo = mid + 1;
+	}
+
+	return conf->disks + lo;
+}
+
+/**
+ *	linear_mergeable_bvec -- tell bio layer if two requests can be merged
+ *	@q: request queue
+ *	@bvm: properties of new bio
+ *	@biovec: the request that could be merged to it.
+ *
+ *	Return amount of bytes we can take at this offset
+ */
+static int linear_mergeable_bvec(struct request_queue *q,
+				 struct bvec_merge_data *bvm,
+				 struct bio_vec *biovec)
+{
+	mddev_t *mddev = q->queuedata;
+	dev_info_t *dev0;
+	unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
+	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
+
+	rcu_read_lock();
+	dev0 = which_dev(mddev, sector);
+	maxsectors = dev0->end_sector - sector;
+	rcu_read_unlock();
+
+	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 int linear_congested(void *data, int bits)
+{
+	mddev_t *mddev = data;
+	linear_conf_t *conf;
+	int i, ret = 0;
+
+	if (mddev_congested(mddev, bits))
+		return 1;
+
+	rcu_read_lock();
+	conf = rcu_dereference(mddev->private);
+
+	for (i = 0; i < mddev->raid_disks && !ret ; i++) {
+		struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
+		ret |= bdi_congested(&q->backing_dev_info, bits);
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
+{
+	linear_conf_t *conf;
+	sector_t array_sectors;
+
+	rcu_read_lock();
+	conf = rcu_dereference(mddev->private);
+	WARN_ONCE(sectors || raid_disks,
+		  "%s does not support generic reshape\n", __func__);
+	array_sectors = conf->array_sectors;
+	rcu_read_unlock();
+
+	return array_sectors;
+}
+
+static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
+{
+	linear_conf_t *conf;
+	mdk_rdev_t *rdev;
+	int i, cnt;
+
+	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
+			GFP_KERNEL);
+	if (!conf)
+		return NULL;
+
+	cnt = 0;
+	conf->array_sectors = 0;
+
+	list_for_each_entry(rdev, &mddev->disks, same_set) {
+		int j = rdev->raid_disk;
+		dev_info_t *disk = conf->disks + j;
+		sector_t sectors;
+
+		if (j < 0 || j >= raid_disks || disk->rdev) {
+			printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
+			       mdname(mddev));
+			goto out;
+		}
+
+		disk->rdev = rdev;
+		if (mddev->chunk_sectors) {
+			sectors = rdev->sectors;
+			sector_div(sectors, mddev->chunk_sectors);
+			rdev->sectors = sectors * mddev->chunk_sectors;
+		}
+
+		disk_stack_limits(mddev->gendisk, rdev->bdev,
+				  rdev->data_offset << 9);
+		/* as we don't honour merge_bvec_fn, we must never risk
+		 * violating it, so limit max_segments to 1 lying within
+		 * a single page.
+		 */
+		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
+			blk_queue_max_segments(mddev->queue, 1);
+			blk_queue_segment_boundary(mddev->queue,
+						   PAGE_CACHE_SIZE - 1);
+		}
+
+		conf->array_sectors += rdev->sectors;
+		cnt++;
+
+	}
+	if (cnt != raid_disks) {
+		printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
+		       mdname(mddev));
+		goto out;
+	}
+
+	/*
+	 * Here we calculate the device offsets.
+	 */
+	conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
+
+	for (i = 1; i < raid_disks; i++)
+		conf->disks[i].end_sector =
+			conf->disks[i-1].end_sector +
+			conf->disks[i].rdev->sectors;
+
+	return conf;
+
+out:
+	kfree(conf);
+	return NULL;
+}
+
+static int linear_run (mddev_t *mddev)
+{
+	linear_conf_t *conf;
+
+	if (md_check_no_bitmap(mddev))
+		return -EINVAL;
+	conf = linear_conf(mddev, mddev->raid_disks);
+
+	if (!conf)
+		return 1;
+	mddev->private = conf;
+	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
+
+	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
+	mddev->queue->backing_dev_info.congested_fn = linear_congested;
+	mddev->queue->backing_dev_info.congested_data = mddev;
+	return md_integrity_register(mddev);
+}
+
+static void free_conf(struct rcu_head *head)
+{
+	linear_conf_t *conf = container_of(head, linear_conf_t, rcu);
+	kfree(conf);
+}
+
+static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+	/* Adding a drive to a linear array allows the array to grow.
+	 * It is permitted if the new drive has a matching superblock
+	 * already on it, with raid_disk equal to raid_disks.
+	 * It is achieved by creating a new linear_private_data structure
+	 * and swapping it in in-place of the current one.
+	 * The current one is never freed until the array is stopped.
+	 * This avoids races.
+	 */
+	linear_conf_t *newconf, *oldconf;
+
+	if (rdev->saved_raid_disk != mddev->raid_disks)
+		return -EINVAL;
+
+	rdev->raid_disk = rdev->saved_raid_disk;
+
+	newconf = linear_conf(mddev,mddev->raid_disks+1);
+
+	if (!newconf)
+		return -ENOMEM;
+
+	oldconf = rcu_dereference(mddev->private);
+	mddev->raid_disks++;
+	rcu_assign_pointer(mddev->private, newconf);
+	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
+	set_capacity(mddev->gendisk, mddev->array_sectors);
+	revalidate_disk(mddev->gendisk);
+	call_rcu(&oldconf->rcu, free_conf);
+	return 0;
+}
+
+static int linear_stop (mddev_t *mddev)
+{
+	linear_conf_t *conf = mddev->private;
+
+	/*
+	 * We do not require rcu protection here since
+	 * we hold reconfig_mutex for both linear_add and
+	 * linear_stop, so they cannot race.
+	 * We should make sure any old 'conf's are properly
+	 * freed though.
+	 */
+	rcu_barrier();
+	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
+	kfree(conf);
+	mddev->private = NULL;
+
+	return 0;
+}
+
+static int linear_make_request (mddev_t *mddev, struct bio *bio)
+{
+	dev_info_t *tmp_dev;
+	sector_t start_sector;
+
+	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bio);
+		return 0;
+	}
+
+	rcu_read_lock();
+	tmp_dev = which_dev(mddev, bio->bi_sector);
+	start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
+
+
+	if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
+		     || (bio->bi_sector < start_sector))) {
+		char b[BDEVNAME_SIZE];
+
+		printk(KERN_ERR
+		       "md/linear:%s: make_request: Sector %llu out of bounds on "
+		       "dev %s: %llu sectors, offset %llu\n",
+		       mdname(mddev),
+		       (unsigned long long)bio->bi_sector,
+		       bdevname(tmp_dev->rdev->bdev, b),
+		       (unsigned long long)tmp_dev->rdev->sectors,
+		       (unsigned long long)start_sector);
+		rcu_read_unlock();
+		bio_io_error(bio);
+		return 0;
+	}
+	if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
+		     tmp_dev->end_sector)) {
+		/* This bio crosses a device boundary, so we have to
+		 * split it.
+		 */
+		struct bio_pair *bp;
+		sector_t end_sector = tmp_dev->end_sector;
+
+		rcu_read_unlock();
+
+		bp = bio_split(bio, end_sector - bio->bi_sector);
+
+		if (linear_make_request(mddev, &bp->bio1))
+			generic_make_request(&bp->bio1);
+		if (linear_make_request(mddev, &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 - start_sector
+		+ tmp_dev->rdev->data_offset;
+	rcu_read_unlock();
+
+	return 1;
+}
+
+static void linear_status (struct seq_file *seq, mddev_t *mddev)
+{
+
+	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
+}
+
+
+static struct mdk_personality linear_personality =
+{
+	.name		= "linear",
+	.level		= LEVEL_LINEAR,
+	.owner		= THIS_MODULE,
+	.make_request	= linear_make_request,
+	.run		= linear_run,
+	.stop		= linear_stop,
+	.status		= linear_status,
+	.hot_add_disk	= linear_add,
+	.size		= linear_size,
+};
+
+static int __init linear_init (void)
+{
+	return register_md_personality (&linear_personality);
+}
+
+static void linear_exit (void)
+{
+	unregister_md_personality (&linear_personality);
+}
+
+
+module_init(linear_init);
+module_exit(linear_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Linear device concatenation personality for MD");
+MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
+MODULE_ALIAS("md-linear");
+MODULE_ALIAS("md-level--1");