404 lines
10 KiB
C
404 lines
10 KiB
C
/*
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linear.c : Multiple Devices driver for Linux
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Copyright (C) 1994-96 Marc ZYNGIER
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<zyngier@ufr-info-p7.ibp.fr> or
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<maz@gloups.fdn.fr>
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Linear mode management functions.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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You should have received a copy of the GNU General Public License
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(for example /usr/src/linux/COPYING); if not, write to the Free
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Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/raid/linear.h>
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/*
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* find which device holds a particular offset
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*/
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static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
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{
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dev_info_t *hash;
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linear_conf_t *conf = mddev_to_conf(mddev);
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/*
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* sector_div(a,b) returns the remainer and sets a to a/b
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*/
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sector >>= conf->sector_shift;
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(void)sector_div(sector, conf->spacing);
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hash = conf->hash_table[sector];
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while (sector >= hash->num_sectors + hash->start_sector)
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hash++;
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return hash;
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}
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/**
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* linear_mergeable_bvec -- tell bio layer if two requests can be merged
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* @q: request queue
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* @bvm: properties of new bio
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* @biovec: the request that could be merged to it.
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*
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* Return amount of bytes we can take at this offset
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*/
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static int linear_mergeable_bvec(struct request_queue *q,
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struct bvec_merge_data *bvm,
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struct bio_vec *biovec)
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{
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mddev_t *mddev = q->queuedata;
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dev_info_t *dev0;
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unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
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sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
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dev0 = which_dev(mddev, sector);
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maxsectors = dev0->num_sectors - (sector - dev0->start_sector);
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if (maxsectors < bio_sectors)
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maxsectors = 0;
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else
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maxsectors -= bio_sectors;
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if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
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return biovec->bv_len;
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/* The bytes available at this offset could be really big,
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* so we cap at 2^31 to avoid overflow */
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if (maxsectors > (1 << (31-9)))
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return 1<<31;
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return maxsectors << 9;
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}
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static void linear_unplug(struct request_queue *q)
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{
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mddev_t *mddev = q->queuedata;
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linear_conf_t *conf = mddev_to_conf(mddev);
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int i;
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for (i=0; i < mddev->raid_disks; i++) {
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struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
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blk_unplug(r_queue);
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}
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}
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static int linear_congested(void *data, int bits)
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{
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mddev_t *mddev = data;
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linear_conf_t *conf = mddev_to_conf(mddev);
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int i, ret = 0;
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for (i = 0; i < mddev->raid_disks && !ret ; i++) {
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struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
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ret |= bdi_congested(&q->backing_dev_info, bits);
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}
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return ret;
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}
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static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
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{
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linear_conf_t *conf;
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dev_info_t **table;
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mdk_rdev_t *rdev;
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int i, nb_zone, cnt;
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sector_t min_sectors;
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sector_t curr_sector;
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struct list_head *tmp;
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conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
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GFP_KERNEL);
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if (!conf)
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return NULL;
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cnt = 0;
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conf->array_sectors = 0;
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rdev_for_each(rdev, tmp, mddev) {
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int j = rdev->raid_disk;
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dev_info_t *disk = conf->disks + j;
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if (j < 0 || j >= raid_disks || disk->rdev) {
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printk("linear: disk numbering problem. Aborting!\n");
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goto out;
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}
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disk->rdev = rdev;
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blk_queue_stack_limits(mddev->queue,
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rdev->bdev->bd_disk->queue);
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/* as we don't honour merge_bvec_fn, we must never risk
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* violating it, so limit ->max_sector to one PAGE, as
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* a one page request is never in violation.
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*/
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if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
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mddev->queue->max_sectors > (PAGE_SIZE>>9))
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blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
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disk->num_sectors = rdev->size * 2;
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conf->array_sectors += rdev->size * 2;
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cnt++;
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}
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if (cnt != raid_disks) {
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printk("linear: not enough drives present. Aborting!\n");
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goto out;
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}
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min_sectors = conf->array_sectors;
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sector_div(min_sectors, PAGE_SIZE/sizeof(struct dev_info *));
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if (min_sectors == 0)
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min_sectors = 1;
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/* min_sectors is the minimum spacing that will fit the hash
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* table in one PAGE. This may be much smaller than needed.
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* We find the smallest non-terminal set of consecutive devices
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* that is larger than min_sectors and use the size of that as
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* the actual spacing
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*/
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conf->spacing = conf->array_sectors;
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for (i=0; i < cnt-1 ; i++) {
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sector_t tmp = 0;
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int j;
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for (j = i; j < cnt - 1 && tmp < min_sectors; j++)
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tmp += conf->disks[j].num_sectors;
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if (tmp >= min_sectors && tmp < conf->spacing)
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conf->spacing = tmp;
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}
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/* spacing may be too large for sector_div to work with,
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* so we might need to pre-shift
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*/
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conf->sector_shift = 0;
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if (sizeof(sector_t) > sizeof(u32)) {
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sector_t space = conf->spacing;
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while (space > (sector_t)(~(u32)0)) {
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space >>= 1;
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conf->sector_shift++;
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}
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}
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/*
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* This code was restructured to work around a gcc-2.95.3 internal
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* compiler error. Alter it with care.
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*/
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{
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sector_t sz;
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unsigned round;
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unsigned long base;
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sz = conf->array_sectors >> conf->sector_shift;
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sz += 1; /* force round-up */
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base = conf->spacing >> conf->sector_shift;
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round = sector_div(sz, base);
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nb_zone = sz + (round ? 1 : 0);
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}
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BUG_ON(nb_zone > PAGE_SIZE / sizeof(struct dev_info *));
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conf->hash_table = kmalloc (sizeof (struct dev_info *) * nb_zone,
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GFP_KERNEL);
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if (!conf->hash_table)
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goto out;
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/*
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* Here we generate the linear hash table
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* First calculate the device offsets.
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*/
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conf->disks[0].start_sector = 0;
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for (i = 1; i < raid_disks; i++)
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conf->disks[i].start_sector =
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conf->disks[i-1].start_sector +
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conf->disks[i-1].num_sectors;
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table = conf->hash_table;
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i = 0;
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for (curr_sector = 0;
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curr_sector < conf->array_sectors;
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curr_sector += conf->spacing) {
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while (i < raid_disks-1 &&
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curr_sector >= conf->disks[i+1].start_sector)
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i++;
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*table ++ = conf->disks + i;
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}
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if (conf->sector_shift) {
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conf->spacing >>= conf->sector_shift;
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/* round spacing up so that when we divide by it,
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* we err on the side of "too-low", which is safest.
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*/
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conf->spacing++;
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}
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BUG_ON(table - conf->hash_table > nb_zone);
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return conf;
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out:
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kfree(conf);
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return NULL;
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}
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static int linear_run (mddev_t *mddev)
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{
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linear_conf_t *conf;
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mddev->queue->queue_lock = &mddev->queue->__queue_lock;
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conf = linear_conf(mddev, mddev->raid_disks);
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if (!conf)
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return 1;
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mddev->private = conf;
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mddev->array_sectors = conf->array_sectors;
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blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
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mddev->queue->unplug_fn = linear_unplug;
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mddev->queue->backing_dev_info.congested_fn = linear_congested;
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mddev->queue->backing_dev_info.congested_data = mddev;
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return 0;
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}
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static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
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{
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/* Adding a drive to a linear array allows the array to grow.
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* It is permitted if the new drive has a matching superblock
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* already on it, with raid_disk equal to raid_disks.
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* It is achieved by creating a new linear_private_data structure
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* and swapping it in in-place of the current one.
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* The current one is never freed until the array is stopped.
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* This avoids races.
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*/
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linear_conf_t *newconf;
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if (rdev->saved_raid_disk != mddev->raid_disks)
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return -EINVAL;
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rdev->raid_disk = rdev->saved_raid_disk;
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newconf = linear_conf(mddev,mddev->raid_disks+1);
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if (!newconf)
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return -ENOMEM;
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newconf->prev = mddev_to_conf(mddev);
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mddev->private = newconf;
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mddev->raid_disks++;
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mddev->array_sectors = newconf->array_sectors;
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set_capacity(mddev->gendisk, mddev->array_sectors);
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return 0;
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}
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static int linear_stop (mddev_t *mddev)
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{
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linear_conf_t *conf = mddev_to_conf(mddev);
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blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
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do {
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linear_conf_t *t = conf->prev;
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kfree(conf->hash_table);
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kfree(conf);
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conf = t;
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} while (conf);
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return 0;
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}
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static int linear_make_request (struct request_queue *q, struct bio *bio)
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{
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const int rw = bio_data_dir(bio);
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mddev_t *mddev = q->queuedata;
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dev_info_t *tmp_dev;
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int cpu;
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if (unlikely(bio_barrier(bio))) {
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bio_endio(bio, -EOPNOTSUPP);
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return 0;
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}
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cpu = part_stat_lock();
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part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
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part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
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bio_sectors(bio));
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part_stat_unlock();
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tmp_dev = which_dev(mddev, bio->bi_sector);
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if (unlikely(bio->bi_sector >= (tmp_dev->num_sectors +
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tmp_dev->start_sector)
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|| (bio->bi_sector <
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tmp_dev->start_sector))) {
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char b[BDEVNAME_SIZE];
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printk("linear_make_request: Sector %llu out of bounds on "
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"dev %s: %llu sectors, offset %llu\n",
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(unsigned long long)bio->bi_sector,
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bdevname(tmp_dev->rdev->bdev, b),
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(unsigned long long)tmp_dev->num_sectors,
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(unsigned long long)tmp_dev->start_sector);
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bio_io_error(bio);
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return 0;
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}
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if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
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tmp_dev->start_sector + tmp_dev->num_sectors)) {
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/* This bio crosses a device boundary, so we have to
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* split it.
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*/
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struct bio_pair *bp;
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bp = bio_split(bio,
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tmp_dev->start_sector + tmp_dev->num_sectors
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- bio->bi_sector);
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if (linear_make_request(q, &bp->bio1))
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generic_make_request(&bp->bio1);
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if (linear_make_request(q, &bp->bio2))
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generic_make_request(&bp->bio2);
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bio_pair_release(bp);
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return 0;
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}
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bio->bi_bdev = tmp_dev->rdev->bdev;
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bio->bi_sector = bio->bi_sector - tmp_dev->start_sector
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+ tmp_dev->rdev->data_offset;
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return 1;
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}
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static void linear_status (struct seq_file *seq, mddev_t *mddev)
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{
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seq_printf(seq, " %dk rounding", mddev->chunk_size/1024);
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}
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static struct mdk_personality linear_personality =
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{
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.name = "linear",
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.level = LEVEL_LINEAR,
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.owner = THIS_MODULE,
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.make_request = linear_make_request,
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.run = linear_run,
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.stop = linear_stop,
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.status = linear_status,
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.hot_add_disk = linear_add,
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};
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static int __init linear_init (void)
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{
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return register_md_personality (&linear_personality);
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}
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static void linear_exit (void)
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{
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unregister_md_personality (&linear_personality);
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}
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module_init(linear_init);
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module_exit(linear_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
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MODULE_ALIAS("md-linear");
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MODULE_ALIAS("md-level--1");
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