/*
   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/module.h>
#include <linux/raid/raid0.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER
#define MD_PERSONALITY

static void raid0_unplug(struct request_queue *q)
{
        mddev_t *mddev = q->queuedata;
        raid0_conf_t *conf = mddev_to_conf(mddev);
        mdk_rdev_t **devlist = conf->strip_zone[0].dev;
        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_to_conf(mddev);
        mdk_rdev_t **devlist = conf->strip_zone[0].dev;
        int i, ret = 0;

        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;
}


static int create_strip_zones (mddev_t *mddev)
{
        int i, c, j;
        sector_t current_offset, curr_zone_offset;
        sector_t min_spacing;
        raid0_conf_t *conf = mddev_to_conf(mddev);
        mdk_rdev_t *smallest, *rdev1, *rdev2, *rdev;
        struct list_head *tmp1, *tmp2;
        struct strip_zone *zone;
        int cnt;
        char b[BDEVNAME_SIZE];
 
        /*
         * The number of 'same size groups'
         */
        conf->nr_strip_zones = 0;
 
        ITERATE_RDEV(mddev,rdev1,tmp1) {
                printk("raid0: looking at %s\n",
                        bdevname(rdev1->bdev,b));
                c = 0;
                ITERATE_RDEV(mddev,rdev2,tmp2) {
                        printk("raid0:   comparing %s(%llu)",
                               bdevname(rdev1->bdev,b),
                               (unsigned long long)rdev1->size);
                        printk(" with %s(%llu)\n",
                               bdevname(rdev2->bdev,b),
                               (unsigned long long)rdev2->size);
                        if (rdev2 == rdev1) {
                                printk("raid0:   END\n");
                                break;
                        }
                        if (rdev2->size == rdev1->size)
                        {
                                /*
                                 * Not unique, don't count it as a new
                                 * group
                                 */
                                printk("raid0:   EQUAL\n");
                                c = 1;
                                break;
                        }
                        printk("raid0:   NOT EQUAL\n");
                }
                if (!c) {
                        printk("raid0:   ==> UNIQUE\n");
                        conf->nr_strip_zones++;
                        printk("raid0: %d zones\n", conf->nr_strip_zones);
                }
        }
        printk("raid0: FINAL %d zones\n", conf->nr_strip_zones);

        conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
                                conf->nr_strip_zones, GFP_KERNEL);
        if (!conf->strip_zone)
                return 1;
        conf->devlist = kzalloc(sizeof(mdk_rdev_t*)*
                                conf->nr_strip_zones*mddev->raid_disks,
                                GFP_KERNEL);
        if (!conf->devlist)
                return 1;

        /* 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;
        zone->dev = conf->devlist;
        ITERATE_RDEV(mddev, rdev1, tmp1) {
                int j = rdev1->raid_disk;

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

                blk_queue_stack_limits(mddev->queue,
                                       rdev1->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 (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
                    mddev->queue->max_sectors > (PAGE_SIZE>>9))
                        blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

                if (!smallest || (rdev1->size <smallest->size))
                        smallest = rdev1;
                cnt++;
        }
        if (cnt != mddev->raid_disks) {
                printk("raid0: too few disks (%d of %d) - aborting!\n",
                        cnt, mddev->raid_disks);
                goto abort;
        }
        zone->nb_dev = cnt;
        zone->size = smallest->size * cnt;
        zone->zone_offset = 0;

        current_offset = smallest->size;
        curr_zone_offset = zone->size;

        /* now do the other zones */
        for (i = 1; i < conf->nr_strip_zones; i++)
        {
                zone = conf->strip_zone + i;
                zone->dev = conf->strip_zone[i-1].dev + mddev->raid_disks;

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

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

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

                zone->zone_offset = curr_zone_offset;
                curr_zone_offset += zone->size;

                current_offset = smallest->size;
                printk("raid0: current zone offset: %llu\n",
                        (unsigned long long)current_offset);
        }

        /* Now find appropriate hash spacing.
         * We want a number which causes most hash entries to cover
         * at most two strips, but the hash table must be at most
         * 1 PAGE.  We choose the smallest strip, or contiguous collection
         * of strips, that has big enough size.  We never consider the last
         * strip though as it's size has no bearing on the efficacy of the hash
         * table.
         */
        conf->hash_spacing = curr_zone_offset;
        min_spacing = curr_zone_offset;
        sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
        for (i=0; i < conf->nr_strip_zones-1; i++) {
                sector_t sz = 0;
                for (j=i; j<conf->nr_strip_zones-1 &&
                             sz < min_spacing ; j++)
                        sz += conf->strip_zone[j].size;
                if (sz >= min_spacing && sz < conf->hash_spacing)
                        conf->hash_spacing = sz;
        }

        mddev->queue->unplug_fn = raid0_unplug;

        mddev->queue->backing_dev_info.congested_fn = raid0_congested;
        mddev->queue->backing_dev_info.congested_data = mddev;

        printk("raid0: done.\n");
        return 0;
 abort:
        return 1;
}

/**
 *      raid0_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 accept at this offset
 */
static int raid0_mergeable_bvec(struct request_queue *q, struct bio *bio, struct bio_vec *biovec)
{
        mddev_t *mddev = q->queuedata;
        sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
        int max;
        unsigned int chunk_sectors = mddev->chunk_size >> 9;
        unsigned int bio_sectors = bio->bi_size >> 9;

        max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + 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 int raid0_run (mddev_t *mddev)
{
        unsigned  cur=0, i=0, nb_zone;
        s64 size;
        raid0_conf_t *conf;
        mdk_rdev_t *rdev;
        struct list_head *tmp;

        if (mddev->chunk_size == 0) {
                printk(KERN_ERR "md/raid0: non-zero chunk size required.\n");
                return -EINVAL;
        }
        printk(KERN_INFO "%s: setting max_sectors to %d, segment boundary to %d\n",
               mdname(mddev),
               mddev->chunk_size >> 9,
               (mddev->chunk_size>>1)-1);
        blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
        blk_queue_segment_boundary(mddev->queue, (mddev->chunk_size>>1) - 1);

        conf = kmalloc(sizeof (raid0_conf_t), GFP_KERNEL);
        if (!conf)
                goto out;
        mddev->private = (void *)conf;
 
        conf->strip_zone = NULL;
        conf->devlist = NULL;
        if (create_strip_zones (mddev)) 
                goto out_free_conf;

        /* calculate array device size */
        mddev->array_size = 0;
        ITERATE_RDEV(mddev,rdev,tmp)
                mddev->array_size += rdev->size;

        printk("raid0 : md_size is %llu blocks.\n", 
                (unsigned long long)mddev->array_size);
        printk("raid0 : conf->hash_spacing is %llu blocks.\n",
                (unsigned long long)conf->hash_spacing);
        {
                sector_t s = mddev->array_size;
                sector_t space = conf->hash_spacing;
                int round;
                conf->preshift = 0;
                if (sizeof(sector_t) > sizeof(u32)) {
                        /*shift down space and s so that sector_div will work */
                        while (space > (sector_t) (~(u32)0)) {
                                s >>= 1;
                                space >>= 1;
                                s += 1; /* force round-up */
                                conf->preshift++;
                        }
                }
                round = sector_div(s, (u32)space) ? 1 : 0;
                nb_zone = s + round;
        }
        printk("raid0 : nb_zone is %d.\n", nb_zone);

        printk("raid0 : Allocating %Zd bytes for hash.\n",
                                nb_zone*sizeof(struct strip_zone*));
        conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
        if (!conf->hash_table)
                goto out_free_conf;
        size = conf->strip_zone[cur].size;

        conf->hash_table[0] = conf->strip_zone + cur;
        for (i=1; i< nb_zone; i++) {
                while (size <= conf->hash_spacing) {
                        cur++;
                        size += conf->strip_zone[cur].size;
                }
                size -= conf->hash_spacing;
                conf->hash_table[i] = conf->strip_zone + cur;
        }
        if (conf->preshift) {
                conf->hash_spacing >>= conf->preshift;
                /* round hash_spacing up so when we divide by it, we
                 * err on the side of too-low, which is safest
                 */
                conf->hash_spacing++;
        }

        /* 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_size / 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);
        return 0;

out_free_conf:
        kfree(conf->strip_zone);
        kfree(conf->devlist);
        kfree(conf);
        mddev->private = NULL;
out:
        return -ENOMEM;
}

static int raid0_stop (mddev_t *mddev)
{
        raid0_conf_t *conf = mddev_to_conf(mddev);

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

        return 0;
}

static int raid0_make_request (struct request_queue *q, struct bio *bio)
{
        mddev_t *mddev = q->queuedata;
        unsigned int sect_in_chunk, chunksize_bits,  chunk_size, chunk_sects;
        raid0_conf_t *conf = mddev_to_conf(mddev);
        struct strip_zone *zone;
        mdk_rdev_t *tmp_dev;
        sector_t chunk;
        sector_t block, rsect;
        const int rw = bio_data_dir(bio);

        if (unlikely(bio_barrier(bio))) {
                bio_endio(bio, -EOPNOTSUPP);
                return 0;
        }

        disk_stat_inc(mddev->gendisk, ios[rw]);
        disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));

        chunk_size = mddev->chunk_size >> 10;
        chunk_sects = mddev->chunk_size >> 9;
        chunksize_bits = ffz(~chunk_size);
        block = bio->bi_sector >> 1;
        

        if (unlikely(chunk_sects < (bio->bi_sector & (chunk_sects - 1)) + (bio->bi_size >> 9))) {
                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.
                 */
                bp = bio_split(bio, bio_split_pool, chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
                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_t x = block >> conf->preshift;
                sector_div(x, (u32)conf->hash_spacing);
                zone = conf->hash_table[x];
        }
 
        while (block >= (zone->zone_offset + zone->size)) 
                zone++;
    
        sect_in_chunk = bio->bi_sector & ((chunk_size<<1) -1);


        {
                sector_t x =  (block - zone->zone_offset) >> chunksize_bits;

                sector_div(x, zone->nb_dev);
                chunk = x;

                x = block >> chunksize_bits;
                tmp_dev = zone->dev[sector_div(x, zone->nb_dev)];
        }
        rsect = (((chunk << chunksize_bits) + zone->dev_offset)<<1)
                + sect_in_chunk;
 
        bio->bi_bdev = tmp_dev->bdev;
        bio->bi_sector = rsect + 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_size, 
                (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_to_conf(mddev);

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

                seq_printf(seq, "] zo=%d do=%d s=%d\n",
                                conf->strip_zone[j].zone_offset,
                                conf->strip_zone[j].dev_offset,
                                conf->strip_zone[j].size);
        }
#endif
        seq_printf(seq, " %dk chunks", mddev->chunk_size/1024);
        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,
};

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_ALIAS("md-personality-2"); /* RAID0 */
MODULE_ALIAS("md-raid0");
MODULE_ALIAS("md-level-0");