Linux 2.6.34-rc3

[pohmelfs.git] / drivers / md / raid0.c

/*
   raid0.c : Multiple Devices driver for Linux
             Copyright (C) 1994-96 Marc ZYNGIER
             <zyngier@ufr-info-p7.ibp.fr> or
             <maz@gloups.fdn.fr>
             Copyright (C) 1999, 2000 Ingo Molnar, Red Hat


   RAID-0 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/seq_file.h>
#include "md.h"
#include "raid0.h"

static void raid0_unplug(struct request_queue *q)
{
        mddev_t *mddev = q->queuedata;
        raid0_conf_t *conf = mddev->private;
        mdk_rdev_t **devlist = conf->devlist;
        int i;

        for (i=0; i<mddev->raid_disks; i++) {
                struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);

                blk_unplug(r_queue);
        }
}

static int raid0_congested(void *data, int bits)
{
        mddev_t *mddev = data;
        raid0_conf_t *conf = mddev->private;
        mdk_rdev_t **devlist = conf->devlist;
        int i, ret = 0;

        if (mddev_congested(mddev, bits))
                return 1;

        for (i = 0; i < mddev->raid_disks && !ret ; i++) {
                struct request_queue *q = bdev_get_queue(devlist[i]->bdev);

                ret |= bdi_congested(&q->backing_dev_info, bits);
        }
        return ret;
}

/*
 * inform the user of the raid configuration
*/
static void dump_zones(mddev_t *mddev)
{
        int j, k, h;
        sector_t zone_size = 0;
        sector_t zone_start = 0;
        char b[BDEVNAME_SIZE];
        raid0_conf_t *conf = mddev->private;
        printk(KERN_INFO "******* %s configuration *********\n",
                mdname(mddev));
        h = 0;
        for (j = 0; j < conf->nr_strip_zones; j++) {
                printk(KERN_INFO "zone%d=[", j);
                for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
                        printk("%s/",
                        bdevname(conf->devlist[j*mddev->raid_disks
                                                + k]->bdev, b));
                printk("]\n");

                zone_size  = conf->strip_zone[j].zone_end - zone_start;
                printk(KERN_INFO "        zone offset=%llukb "
                                "device offset=%llukb size=%llukb\n",
                        (unsigned long long)zone_start>>1,
                        (unsigned long long)conf->strip_zone[j].dev_start>>1,
                        (unsigned long long)zone_size>>1);
                zone_start = conf->strip_zone[j].zone_end;
        }
        printk(KERN_INFO "**********************************\n\n");
}

static int create_strip_zones(mddev_t *mddev)
{
        int i, c, err;
        sector_t curr_zone_end, sectors;
        mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev, **dev;
        struct strip_zone *zone;
        int cnt;
        char b[BDEVNAME_SIZE];
        raid0_conf_t *conf = kzalloc(sizeof(*conf), GFP_KERNEL);

        if (!conf)
                return -ENOMEM;
        list_for_each_entry(rdev1, &mddev->disks, same_set) {
                printk(KERN_INFO "raid0: looking at %s\n",
                        bdevname(rdev1->bdev,b));
                c = 0;

                /* round size to chunk_size */
                sectors = rdev1->sectors;
                sector_div(sectors, mddev->chunk_sectors);
                rdev1->sectors = sectors * mddev->chunk_sectors;

                list_for_each_entry(rdev2, &mddev->disks, same_set) {
                        printk(KERN_INFO "raid0:   comparing %s(%llu)",
                               bdevname(rdev1->bdev,b),
                               (unsigned long long)rdev1->sectors);
                        printk(KERN_INFO " with %s(%llu)\n",
                               bdevname(rdev2->bdev,b),
                               (unsigned long long)rdev2->sectors);
                        if (rdev2 == rdev1) {
                                printk(KERN_INFO "raid0:   END\n");
                                break;
                        }
                        if (rdev2->sectors == rdev1->sectors) {
                                /*
                                 * Not unique, don't count it as a new
                                 * group
                                 */
                                printk(KERN_INFO "raid0:   EQUAL\n");
                                c = 1;
                                break;
                        }
                        printk(KERN_INFO "raid0:   NOT EQUAL\n");
                }
                if (!c) {
                        printk(KERN_INFO "raid0:   ==> UNIQUE\n");
                        conf->nr_strip_zones++;
                        printk(KERN_INFO "raid0: %d zones\n",
                                conf->nr_strip_zones);
                }
        }
        printk(KERN_INFO "raid0: FINAL %d zones\n", conf->nr_strip_zones);
        err = -ENOMEM;
        conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
                                conf->nr_strip_zones, GFP_KERNEL);
        if (!conf->strip_zone)
                goto abort;
        conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
                                conf->nr_strip_zones*mddev->raid_disks,
                                GFP_KERNEL);
        if (!conf->devlist)
                goto abort;

        /* The first zone must contain all devices, so here we check that
         * there is a proper alignment of slots to devices and find them all
         */
        zone = &conf->strip_zone[0];
        cnt = 0;
        smallest = NULL;
        dev = conf->devlist;
        err = -EINVAL;
        list_for_each_entry(rdev1, &mddev->disks, same_set) {
                int j = rdev1->raid_disk;

                if (j < 0 || j >= mddev->raid_disks) {
                        printk(KERN_ERR "raid0: bad disk number %d - "
                                "aborting!\n", j);
                        goto abort;
                }
                if (dev[j]) {
                        printk(KERN_ERR "raid0: multiple devices for %d - "
                                "aborting!\n", j);
                        goto abort;
                }
                dev[j] = rdev1;

                disk_stack_limits(mddev->gendisk, rdev1->bdev,
                                  rdev1->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 (rdev1->bdev->bd_disk->queue->merge_bvec_fn) {
                        blk_queue_max_segments(mddev->queue, 1);
                        blk_queue_segment_boundary(mddev->queue,
                                                   PAGE_CACHE_SIZE - 1);
                }
                if (!smallest || (rdev1->sectors < smallest->sectors))
                        smallest = rdev1;
                cnt++;
        }
        if (cnt != mddev->raid_disks) {
                printk(KERN_ERR "raid0: too few disks (%d of %d) - "
                        "aborting!\n", cnt, mddev->raid_disks);
                goto abort;
        }
        zone->nb_dev = cnt;
        zone->zone_end = smallest->sectors * cnt;

        curr_zone_end = zone->zone_end;

        /* now do the other zones */
        for (i = 1; i < conf->nr_strip_zones; i++)
        {
                int j;

                zone = conf->strip_zone + i;
                dev = conf->devlist + i * mddev->raid_disks;

                printk(KERN_INFO "raid0: zone %d\n", i);
                zone->dev_start = smallest->sectors;
                smallest = NULL;
                c = 0;

                for (j=0; j<cnt; j++) {
                        rdev = conf->devlist[j];
                        printk(KERN_INFO "raid0: checking %s ...",
                                bdevname(rdev->bdev, b));
                        if (rdev->sectors <= zone->dev_start) {
                                printk(KERN_INFO " nope.\n");
                                continue;
                        }
                        printk(KERN_INFO " contained as device %d\n", c);
                        dev[c] = rdev;
                        c++;
                        if (!smallest || rdev->sectors < smallest->sectors) {
                                smallest = rdev;
                                printk(KERN_INFO "  (%llu) is smallest!.\n",
                                        (unsigned long long)rdev->sectors);
                        }
                }

                zone->nb_dev = c;
                sectors = (smallest->sectors - zone->dev_start) * c;
                printk(KERN_INFO "raid0: zone->nb_dev: %d, sectors: %llu\n",
                        zone->nb_dev, (unsigned long long)sectors);

                curr_zone_end += sectors;
                zone->zone_end = curr_zone_end;

                printk(KERN_INFO "raid0: current zone start: %llu\n",
                        (unsigned long long)smallest->sectors);
        }
        mddev->queue->unplug_fn = raid0_unplug;
        mddev->queue->backing_dev_info.congested_fn = raid0_congested;
        mddev->queue->backing_dev_info.congested_data = mddev;

        /*
         * now since we have the hard sector sizes, we can make sure
         * chunk size is a multiple of that sector size
         */
        if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
                printk(KERN_ERR "%s chunk_size of %d not valid\n",
                       mdname(mddev),
                       mddev->chunk_sectors << 9);
                goto abort;
        }

        blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
        blk_queue_io_opt(mddev->queue,
                         (mddev->chunk_sectors << 9) * mddev->raid_disks);

        printk(KERN_INFO "raid0: done.\n");
        mddev->private = conf;
        return 0;
abort:
        kfree(conf->strip_zone);
        kfree(conf->devlist);
        kfree(conf);
        mddev->private = NULL;
        return err;
}

/**
 *      raid0_mergeable_bvec -- tell bio layer if a 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 accept at this offset
 */
static int raid0_mergeable_bvec(struct request_queue *q,
                                struct bvec_merge_data *bvm,
                                struct bio_vec *biovec)
{
        mddev_t *mddev = q->queuedata;
        sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
        int max;
        unsigned int chunk_sectors = mddev->chunk_sectors;
        unsigned int bio_sectors = bvm->bi_size >> 9;

        if (is_power_of_2(chunk_sectors))
                max =  (chunk_sectors - ((sector & (chunk_sectors-1))
                                                + bio_sectors)) << 9;
        else
                max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
                                                + bio_sectors)) << 9;
        if (max < 0) max = 0; /* bio_add cannot handle a negative return */
        if (max <= biovec->bv_len && bio_sectors == 0)
                return biovec->bv_len;
        else 
                return max;
}

static sector_t raid0_size(mddev_t *mddev, sector_t sectors, int raid_disks)
{
        sector_t array_sectors = 0;
        mdk_rdev_t *rdev;

        WARN_ONCE(sectors || raid_disks,
                  "%s does not support generic reshape\n", __func__);

        list_for_each_entry(rdev, &mddev->disks, same_set)
                array_sectors += rdev->sectors;

        return array_sectors;
}

static int raid0_run(mddev_t *mddev)
{
        int ret;

        if (mddev->chunk_sectors == 0) {
                printk(KERN_ERR "md/raid0: chunk size must be set.\n");
                return -EINVAL;
        }
        if (md_check_no_bitmap(mddev))
                return -EINVAL;
        blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
        mddev->queue->queue_lock = &mddev->queue->__queue_lock;

        ret = create_strip_zones(mddev);
        if (ret < 0)
                return ret;

        /* calculate array device size */
        md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));

        printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
                (unsigned long long)mddev->array_sectors);
        /* calculate the max read-ahead size.
         * For read-ahead of large files to be effective, we need to
         * readahead at least twice a whole stripe. i.e. number of devices
         * multiplied by chunk size times 2.
         * If an individual device has an ra_pages greater than the
         * chunk size, then we will not drive that device as hard as it
         * wants.  We consider this a configuration error: a larger
         * chunksize should be used in that case.
         */
        {
                int stripe = mddev->raid_disks *
                        (mddev->chunk_sectors << 9) / PAGE_SIZE;
                if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
                        mddev->queue->backing_dev_info.ra_pages = 2* stripe;
        }

        blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
        dump_zones(mddev);
        md_integrity_register(mddev);
        return 0;
}

static int raid0_stop(mddev_t *mddev)
{
        raid0_conf_t *conf = mddev->private;

        blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
        kfree(conf->strip_zone);
        kfree(conf->devlist);
        kfree(conf);
        mddev->private = NULL;
        return 0;
}

/* Find the zone which holds a particular offset
 * Update *sectorp to be an offset in that zone
 */
static struct strip_zone *find_zone(struct raid0_private_data *conf,
                                    sector_t *sectorp)
{
        int i;
        struct strip_zone *z = conf->strip_zone;
        sector_t sector = *sectorp;

        for (i = 0; i < conf->nr_strip_zones; i++)
                if (sector < z[i].zone_end) {
                        if (i)
                                *sectorp = sector - z[i-1].zone_end;
                        return z + i;
                }
        BUG();
}

/*
 * remaps the bio to the target device. we separate two flows.
 * power 2 flow and a general flow for the sake of perfromance
*/
static mdk_rdev_t *map_sector(mddev_t *mddev, struct strip_zone *zone,
                                sector_t sector, sector_t *sector_offset)
{
        unsigned int sect_in_chunk;
        sector_t chunk;
        raid0_conf_t *conf = mddev->private;
        unsigned int chunk_sects = mddev->chunk_sectors;

        if (is_power_of_2(chunk_sects)) {
                int chunksect_bits = ffz(~chunk_sects);
                /* find the sector offset inside the chunk */
                sect_in_chunk  = sector & (chunk_sects - 1);
                sector >>= chunksect_bits;
                /* chunk in zone */
                chunk = *sector_offset;
                /* quotient is the chunk in real device*/
                sector_div(chunk, zone->nb_dev << chunksect_bits);
        } else{
                sect_in_chunk = sector_div(sector, chunk_sects);
                chunk = *sector_offset;
                sector_div(chunk, chunk_sects * zone->nb_dev);
        }
        /*
        *  position the bio over the real device
        *  real sector = chunk in device + starting of zone
        *       + the position in the chunk
        */
        *sector_offset = (chunk * chunk_sects) + sect_in_chunk;
        return conf->devlist[(zone - conf->strip_zone)*mddev->raid_disks
                             + sector_div(sector, zone->nb_dev)];
}

/*
 * Is io distribute over 1 or more chunks ?
*/
static inline int is_io_in_chunk_boundary(mddev_t *mddev,
                        unsigned int chunk_sects, struct bio *bio)
{
        if (likely(is_power_of_2(chunk_sects))) {
                return chunk_sects >= ((bio->bi_sector & (chunk_sects-1))
                                        + (bio->bi_size >> 9));
        } else{
                sector_t sector = bio->bi_sector;
                return chunk_sects >= (sector_div(sector, chunk_sects)
                                                + (bio->bi_size >> 9));
        }
}

static int raid0_make_request(struct request_queue *q, struct bio *bio)
{
        mddev_t *mddev = q->queuedata;
        unsigned int chunk_sects;
        sector_t sector_offset;
        struct strip_zone *zone;
        mdk_rdev_t *tmp_dev;
        const int rw = bio_data_dir(bio);
        int cpu;

        if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
                md_barrier_request(mddev, bio);
                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();

        chunk_sects = mddev->chunk_sectors;
        if (unlikely(!is_io_in_chunk_boundary(mddev, chunk_sects, bio))) {
                sector_t sector = bio->bi_sector;
                struct bio_pair *bp;
                /* Sanity check -- queue functions should prevent this happening */
                if (bio->bi_vcnt != 1 ||
                    bio->bi_idx != 0)
                        goto bad_map;
                /* This is a one page bio that upper layers
                 * refuse to split for us, so we need to split it.
                 */
                if (likely(is_power_of_2(chunk_sects)))
                        bp = bio_split(bio, chunk_sects - (sector &
                                                           (chunk_sects-1)));
                else
                        bp = bio_split(bio, chunk_sects -
                                       sector_div(sector, chunk_sects));
                if (raid0_make_request(q, &bp->bio1))
                        generic_make_request(&bp->bio1);
                if (raid0_make_request(q, &bp->bio2))
                        generic_make_request(&bp->bio2);

                bio_pair_release(bp);
                return 0;
        }

        sector_offset = bio->bi_sector;
        zone =  find_zone(mddev->private, &sector_offset);
        tmp_dev = map_sector(mddev, zone, bio->bi_sector,
                             &sector_offset);
        bio->bi_bdev = tmp_dev->bdev;
        bio->bi_sector = sector_offset + zone->dev_start +
                tmp_dev->data_offset;
        /*
         * Let the main block layer submit the IO and resolve recursion:
         */
        return 1;

bad_map:
        printk("raid0_make_request bug: can't convert block across chunks"
                " or bigger than %dk %llu %d\n", chunk_sects / 2,
                (unsigned long long)bio->bi_sector, bio->bi_size >> 10);

        bio_io_error(bio);
        return 0;
}

static void raid0_status(struct seq_file *seq, mddev_t *mddev)
{
#undef MD_DEBUG
#ifdef MD_DEBUG
        int j, k, h;
        char b[BDEVNAME_SIZE];
        raid0_conf_t *conf = mddev->private;

        sector_t zone_size;
        sector_t zone_start = 0;
        h = 0;

        for (j = 0; j < conf->nr_strip_zones; j++) {
                seq_printf(seq, "      z%d", j);
                seq_printf(seq, "=[");
                for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
                        seq_printf(seq, "%s/", bdevname(
                                conf->devlist[j*mddev->raid_disks + k]
                                                ->bdev, b));

                zone_size  = conf->strip_zone[j].zone_end - zone_start;
                seq_printf(seq, "] ze=%lld ds=%lld s=%lld\n",
                        (unsigned long long)zone_start>>1,
                        (unsigned long long)conf->strip_zone[j].dev_start>>1,
                        (unsigned long long)zone_size>>1);
                zone_start = conf->strip_zone[j].zone_end;
        }
#endif
        seq_printf(seq, " %dk chunks", mddev->chunk_sectors / 2);
        return;
}

static struct mdk_personality raid0_personality=
{
        .name           = "raid0",
        .level          = 0,
        .owner          = THIS_MODULE,
        .make_request   = raid0_make_request,
        .run            = raid0_run,
        .stop           = raid0_stop,
        .status         = raid0_status,
        .size           = raid0_size,
};

static int __init raid0_init (void)
{
        return register_md_personality (&raid0_personality);
}

static void raid0_exit (void)
{
        unregister_md_personality (&raid0_personality);
}

module_init(raid0_init);
module_exit(raid0_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID0 (striping) personality for MD");
MODULE_ALIAS("md-personality-2"); /* RAID0 */
MODULE_ALIAS("md-raid0");
MODULE_ALIAS("md-level-0");