390 lines
9.4 KiB
C
390 lines
9.4 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/blkdev.h>
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#include <linux/raid/md_u.h>
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#include <linux/seq_file.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include "md.h"
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#include "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 struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
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{
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int lo, mid, hi;
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struct linear_conf *conf;
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lo = 0;
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hi = mddev->raid_disks - 1;
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conf = rcu_dereference(mddev->private);
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/*
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* Binary Search
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*/
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while (hi > lo) {
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mid = (hi + lo) / 2;
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if (sector < conf->disks[mid].end_sector)
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hi = mid;
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else
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lo = mid + 1;
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}
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return conf->disks + lo;
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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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struct mddev *mddev = q->queuedata;
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struct dev_info *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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int maxbytes = biovec->bv_len;
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struct request_queue *subq;
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rcu_read_lock();
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dev0 = which_dev(mddev, sector);
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maxsectors = dev0->end_sector - sector;
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subq = bdev_get_queue(dev0->rdev->bdev);
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if (subq->merge_bvec_fn) {
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bvm->bi_bdev = dev0->rdev->bdev;
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bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors;
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maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
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biovec));
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}
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rcu_read_unlock();
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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 maxbytes;
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if (maxsectors > (maxbytes >> 9))
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return maxbytes;
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else
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return maxsectors << 9;
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}
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static int linear_congested(void *data, int bits)
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{
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struct mddev *mddev = data;
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struct linear_conf *conf;
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int i, ret = 0;
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if (mddev_congested(mddev, bits))
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return 1;
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rcu_read_lock();
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conf = rcu_dereference(mddev->private);
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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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rcu_read_unlock();
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return ret;
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}
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static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
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{
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struct linear_conf *conf;
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sector_t array_sectors;
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rcu_read_lock();
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conf = rcu_dereference(mddev->private);
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WARN_ONCE(sectors || raid_disks,
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"%s does not support generic reshape\n", __func__);
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array_sectors = conf->array_sectors;
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rcu_read_unlock();
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return array_sectors;
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}
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static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
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{
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struct linear_conf *conf;
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struct md_rdev *rdev;
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int i, cnt;
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bool discard_supported = false;
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conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
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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, mddev) {
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int j = rdev->raid_disk;
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struct dev_info *disk = conf->disks + j;
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sector_t sectors;
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if (j < 0 || j >= raid_disks || disk->rdev) {
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printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
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mdname(mddev));
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goto out;
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}
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disk->rdev = rdev;
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if (mddev->chunk_sectors) {
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sectors = rdev->sectors;
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sector_div(sectors, mddev->chunk_sectors);
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rdev->sectors = sectors * mddev->chunk_sectors;
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}
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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conf->array_sectors += rdev->sectors;
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cnt++;
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if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
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discard_supported = true;
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}
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if (cnt != raid_disks) {
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printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
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mdname(mddev));
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goto out;
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}
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if (!discard_supported)
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queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
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else
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queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
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/*
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* Here we calculate the device offsets.
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*/
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conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
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for (i = 1; i < raid_disks; i++)
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conf->disks[i].end_sector =
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conf->disks[i-1].end_sector +
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conf->disks[i].rdev->sectors;
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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 (struct mddev *mddev)
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{
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struct linear_conf *conf;
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int ret;
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if (md_check_no_bitmap(mddev))
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return -EINVAL;
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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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md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
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blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
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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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ret = md_integrity_register(mddev);
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if (ret) {
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kfree(conf);
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mddev->private = NULL;
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}
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return ret;
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}
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static int linear_add(struct mddev *mddev, struct md_rdev *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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struct linear_conf *newconf, *oldconf;
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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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rdev->saved_raid_disk = -1;
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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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oldconf = rcu_dereference_protected(mddev->private,
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lockdep_is_held(
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&mddev->reconfig_mutex));
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mddev->raid_disks++;
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rcu_assign_pointer(mddev->private, newconf);
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md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
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set_capacity(mddev->gendisk, mddev->array_sectors);
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revalidate_disk(mddev->gendisk);
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kfree_rcu(oldconf, rcu);
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return 0;
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}
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static int linear_stop (struct mddev *mddev)
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{
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struct linear_conf *conf =
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rcu_dereference_protected(mddev->private,
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lockdep_is_held(
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&mddev->reconfig_mutex));
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/*
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* We do not require rcu protection here since
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* we hold reconfig_mutex for both linear_add and
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* linear_stop, so they cannot race.
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* We should make sure any old 'conf's are properly
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* freed though.
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*/
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rcu_barrier();
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blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
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kfree(conf);
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mddev->private = NULL;
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return 0;
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}
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static void linear_make_request(struct mddev *mddev, struct bio *bio)
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{
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char b[BDEVNAME_SIZE];
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struct dev_info *tmp_dev;
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struct bio *split;
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sector_t start_sector, end_sector, data_offset;
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if (unlikely(bio->bi_rw & REQ_FLUSH)) {
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md_flush_request(mddev, bio);
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return;
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}
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do {
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rcu_read_lock();
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tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);
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start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
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end_sector = tmp_dev->end_sector;
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data_offset = tmp_dev->rdev->data_offset;
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bio->bi_bdev = tmp_dev->rdev->bdev;
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rcu_read_unlock();
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if (unlikely(bio->bi_iter.bi_sector >= end_sector ||
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bio->bi_iter.bi_sector < start_sector))
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goto out_of_bounds;
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if (unlikely(bio_end_sector(bio) > end_sector)) {
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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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split = bio_split(bio, end_sector -
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bio->bi_iter.bi_sector,
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GFP_NOIO, fs_bio_set);
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bio_chain(split, bio);
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} else {
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split = bio;
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}
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split->bi_iter.bi_sector = split->bi_iter.bi_sector -
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start_sector + data_offset;
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if (unlikely((split->bi_rw & REQ_DISCARD) &&
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!blk_queue_discard(bdev_get_queue(split->bi_bdev)))) {
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/* Just ignore it */
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bio_endio(split, 0);
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} else
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generic_make_request(split);
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} while (split != bio);
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return;
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out_of_bounds:
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printk(KERN_ERR
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"md/linear:%s: make_request: Sector %llu out of bounds on "
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"dev %s: %llu sectors, offset %llu\n",
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mdname(mddev),
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(unsigned long long)bio->bi_iter.bi_sector,
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bdevname(tmp_dev->rdev->bdev, b),
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(unsigned long long)tmp_dev->rdev->sectors,
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(unsigned long long)start_sector);
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bio_io_error(bio);
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}
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static void linear_status (struct seq_file *seq, struct mddev *mddev)
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{
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seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
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}
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static struct md_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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.size = linear_size,
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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_DESCRIPTION("Linear device concatenation personality for MD");
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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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