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-rw-r--r--drivers/md/linear.c403
1 files changed, 403 insertions, 0 deletions
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
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--- /dev/null
+++ b/drivers/md/linear.c
@@ -0,0 +1,403 @@
+/*
+ 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/raid/linear.h>
+
+/*
+ * 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 idx = sector >> conf->sector_shift;
+
+ /*
+ * sector_div(a,b) returns the remainer and sets a to a/b
+ */
+ (void)sector_div(idx, conf->spacing);
+ hash = conf->hash_table[idx];
+
+ while (sector >= hash->num_sectors + hash->start_sector)
+ hash++;
+ return hash;
+}
+
+/**
+ * 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);
+
+ dev0 = which_dev(mddev, sector);
+ maxsectors = dev0->num_sectors - (sector - dev0->start_sector);
+
+ 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(struct request_queue *q)
+{
+ mddev_t *mddev = q->queuedata;
+ linear_conf_t *conf = mddev_to_conf(mddev);
+ int i;
+
+ for (i=0; i < mddev->raid_disks; i++) {
+ struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
+ blk_unplug(r_queue);
+ }
+}
+
+static int linear_congested(void *data, int bits)
+{
+ mddev_t *mddev = data;
+ linear_conf_t *conf = mddev_to_conf(mddev);
+ int i, ret = 0;
+
+ 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);
+ }
+ return ret;
+}
+
+static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
+{
+ linear_conf_t *conf;
+ dev_info_t **table;
+ mdk_rdev_t *rdev;
+ int i, nb_zone, cnt;
+ sector_t min_sectors;
+ sector_t curr_sector;
+ struct list_head *tmp;
+
+ conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
+ GFP_KERNEL);
+ if (!conf)
+ return NULL;
+
+ cnt = 0;
+ conf->array_sectors = 0;
+
+ rdev_for_each(rdev, tmp, mddev) {
+ int j = rdev->raid_disk;
+ dev_info_t *disk = conf->disks + j;
+
+ if (j < 0 || j >= 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->num_sectors = rdev->size * 2;
+ conf->array_sectors += rdev->size * 2;
+
+ cnt++;
+ }
+ if (cnt != raid_disks) {
+ printk("linear: not enough drives present. Aborting!\n");
+ goto out;
+ }
+
+ min_sectors = conf->array_sectors;
+ sector_div(min_sectors, PAGE_SIZE/sizeof(struct dev_info *));
+ if (min_sectors == 0)
+ min_sectors = 1;
+
+ /* min_sectors is the minimum spacing that will fit the hash
+ * table in one PAGE. This may be much smaller than needed.
+ * We find the smallest non-terminal set of consecutive devices
+ * that is larger than min_sectors and use the size of that as
+ * the actual spacing
+ */
+ conf->spacing = conf->array_sectors;
+ for (i=0; i < cnt-1 ; i++) {
+ sector_t tmp = 0;
+ int j;
+ for (j = i; j < cnt - 1 && tmp < min_sectors; j++)
+ tmp += conf->disks[j].num_sectors;
+ if (tmp >= min_sectors && tmp < conf->spacing)
+ conf->spacing = tmp;
+ }
+
+ /* spacing may be too large for sector_div to work with,
+ * so we might need to pre-shift
+ */
+ conf->sector_shift = 0;
+ if (sizeof(sector_t) > sizeof(u32)) {
+ sector_t space = conf->spacing;
+ while (space > (sector_t)(~(u32)0)) {
+ space >>= 1;
+ conf->sector_shift++;
+ }
+ }
+ /*
+ * 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 = conf->array_sectors >> conf->sector_shift;
+ sz += 1; /* force round-up */
+ base = conf->spacing >> conf->sector_shift;
+ round = sector_div(sz, base);
+ nb_zone = sz + (round ? 1 : 0);
+ }
+ BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *));
+
+ conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone,
+ GFP_KERNEL);
+ if (!conf->hash_table)
+ goto out;
+
+ /*
+ * Here we generate the linear hash table
+ * First calculate the device offsets.
+ */
+ conf->disks[0].start_sector = 0;
+ for (i = 1; i < raid_disks; i++)
+ conf->disks[i].start_sector =
+ conf->disks[i-1].start_sector +
+ conf->disks[i-1].num_sectors;
+
+ table = conf->hash_table;
+ i = 0;
+ for (curr_sector = 0;
+ curr_sector < conf->array_sectors;
+ curr_sector += conf->spacing) {
+
+ while (i < raid_disks-1 &&
+ curr_sector >= conf->disks[i+1].start_sector)
+ i++;
+
+ *table ++ = conf->disks + i;
+ }
+
+ if (conf->sector_shift) {
+ conf->spacing >>= conf->sector_shift;
+ /* round spacing up so that when we divide by it,
+ * we err on the side of "too-low", which is safest.
+ */
+ conf->spacing++;
+ }
+
+ BUG_ON(table - conf->hash_table > nb_zone);
+
+ return conf;
+
+out:
+ kfree(conf);
+ return NULL;
+}
+
+static int linear_run (mddev_t *mddev)
+{
+ linear_conf_t *conf;
+
+ mddev->queue->queue_lock = &mddev->queue->__queue_lock;
+ conf = linear_conf(mddev, mddev->raid_disks);
+
+ if (!conf)
+ return 1;
+ mddev->private = conf;
+ mddev->array_sectors = conf->array_sectors;
+
+ blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
+ mddev->queue->unplug_fn = linear_unplug;
+ mddev->queue->backing_dev_info.congested_fn = linear_congested;
+ mddev->queue->backing_dev_info.congested_data = mddev;
+ return 0;
+}
+
+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;
+
+ 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;
+
+ newconf->prev = mddev_to_conf(mddev);
+ mddev->private = newconf;
+ mddev->raid_disks++;
+ mddev->array_sectors = newconf->array_sectors;
+ set_capacity(mddev->gendisk, mddev->array_sectors);
+ return 0;
+}
+
+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'*/
+ do {
+ linear_conf_t *t = conf->prev;
+ kfree(conf->hash_table);
+ kfree(conf);
+ conf = t;
+ } while (conf);
+
+ return 0;
+}
+
+static int linear_make_request (struct request_queue *q, struct bio *bio)
+{
+ const int rw = bio_data_dir(bio);
+ mddev_t *mddev = q->queuedata;
+ dev_info_t *tmp_dev;
+ int cpu;
+
+ if (unlikely(bio_barrier(bio))) {
+ bio_endio(bio, -EOPNOTSUPP);
+ return 0;
+ }
+
+ cpu = part_stat_lock();
+ part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
+ part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
+ bio_sectors(bio));
+ part_stat_unlock();
+
+ tmp_dev = which_dev(mddev, bio->bi_sector);
+
+ if (unlikely(bio->bi_sector >= (tmp_dev->num_sectors +
+ tmp_dev->start_sector)
+ || (bio->bi_sector <
+ tmp_dev->start_sector))) {
+ char b[BDEVNAME_SIZE];
+
+ printk("linear_make_request: Sector %llu out of bounds on "
+ "dev %s: %llu sectors, offset %llu\n",
+ (unsigned long long)bio->bi_sector,
+ bdevname(tmp_dev->rdev->bdev, b),
+ (unsigned long long)tmp_dev->num_sectors,
+ (unsigned long long)tmp_dev->start_sector);
+ bio_io_error(bio);
+ return 0;
+ }
+ if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
+ tmp_dev->start_sector + tmp_dev->num_sectors)) {
+ /* This bio crosses a device boundary, so we have to
+ * split it.
+ */
+ struct bio_pair *bp;
+
+ bp = bio_split(bio,
+ tmp_dev->start_sector + tmp_dev->num_sectors
+ - bio->bi_sector);
+
+ 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->start_sector
+ + tmp_dev->rdev->data_offset;
+
+ return 1;
+}
+
+static void linear_status (struct seq_file *seq, mddev_t *mddev)
+{
+
+ seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
+}
+
+
+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,
+};
+
+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_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
+MODULE_ALIAS("md-linear");
+MODULE_ALIAS("md-level--1");
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