/* 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 */ block >>= conf->preshift; (void)sector_div(block, conf->hash_spacing); hash = conf->hash_table[block]; while ((sector>>1) >= (hash->size + hash->offset)) hash++; return hash; } /** * linear_mergeable_bvec -- tell bio layer if 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 min_spacing; 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; 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; cnt++; } if (cnt != mddev->raid_disks) { printk("linear: not enough drives present. Aborting!\n"); goto out; } min_spacing = mddev->array_size; sector_div(min_spacing, PAGE_SIZE/sizeof(struct dev_info *)); /* min_spacing 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_spacing as use the size of that as * the actual spacing */ conf->hash_spacing = mddev->array_size; for (i=0; i < cnt-1 ; i++) { sector_t sz = 0; int j; for (j=i; i<cnt-1 && sz < min_spacing ; j++) sz += conf->disks[j].size; if (sz >= min_spacing && sz < conf->hash_spacing) conf->hash_spacing = sz; } /* hash_spacing may be too large for sector_div to work with, * so we might need to pre-shift */ conf->preshift = 0; if (sizeof(sector_t) > sizeof(u32)) { sector_t space = conf->hash_spacing; while (space > (sector_t)(~(u32)0)) { space >>= 1; conf->preshift++; } } /* * 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 >> conf->preshift; sz += 1; /* force round-up */ base = conf->hash_spacing >> conf->preshift; 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].offset = 0; for (i=1; i<mddev->raid_disks; i++) conf->disks[i].offset = conf->disks[i-1].offset + conf->disks[i-1].size; table = conf->hash_table; curr_offset = 0; i = 0; for (curr_offset = 0; curr_offset < mddev->array_size; curr_offset += conf->hash_spacing) { while (i < mddev->raid_disks-1 && curr_offset >= conf->disks[i+1].offset) i++; *table ++ = conf->disks + i; } if (conf->preshift) { conf->hash_spacing >>= conf->preshift; /* round hash_spacing up so that when we divide by it, * we err on the side of "too-low", which is safest. */ conf->hash_spacing++; } BUG_ON(table - conf->hash_table > nb_zone); 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: 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) { const int rw = bio_data_dir(bio); mddev_t *mddev = q->queuedata; dev_info_t *tmp_dev; sector_t block; if (unlikely(bio_barrier(bio))) { bio_endio(bio, bio->bi_size, -EOPNOTSUPP); return 0; } disk_stat_inc(mddev->gendisk, ios[rw]); disk_stat_add(mddev->gendisk, sectors[rw], 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, ((tmp_dev->offset + tmp_dev->size)<<1) - 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->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 < mddev->raid_disks; 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 */