drivers/md/md-linear.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
    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.

 */

 #include <linux/blkdev.h>
 #include <linux/raid/md_u.h>
 #include <linux/seq_file.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <trace/events/block.h>
 #include "md.h"
 #include "md-linear.h"

 /*
  * find which device holds a particular offset
  */
 static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
 {
 	int lo, mid, hi;
 	struct linear_conf *conf;

 	lo = 0;
 	hi = mddev->raid_disks - 1;
 	conf = mddev->private;

 	/*
 	 * Binary Search
 	 */

 	while (hi > lo) {

 		mid = (hi + lo) / 2;
 		if (sector < conf->disks[mid].end_sector)
 			hi = mid;
 		else
 			lo = mid + 1;
 	}

 	return conf->disks + lo;
 }

 static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 {
 	struct linear_conf *conf;
 	sector_t array_sectors;

 	conf = mddev->private;
 	WARN_ONCE(sectors || raid_disks,
 		  "%s does not support generic reshape\n", __func__);
 	array_sectors = conf->array_sectors;

 	return array_sectors;
 }

 static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 {
 	struct linear_conf *conf;
 	struct md_rdev *rdev;
 	int i, cnt;
 	bool discard_supported = false;

 	conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
 	if (!conf)
 		return NULL;

 	cnt = 0;
 	conf->array_sectors = 0;

 	rdev_for_each(rdev, mddev) {
 		int j = rdev->raid_disk;
 		struct dev_info *disk = conf->disks + j;
 		sector_t sectors;

 		if (j < 0 || j >= raid_disks || disk->rdev) {
 			pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
 				mdname(mddev));
 			goto out;
 		}

 		disk->rdev = rdev;
 		if (mddev->chunk_sectors) {
 			sectors = rdev->sectors;
 			sector_div(sectors, mddev->chunk_sectors);
 			rdev->sectors = sectors * mddev->chunk_sectors;
 		}

 		disk_stack_limits(mddev->gendisk, rdev->bdev,
 				  rdev->data_offset << 9);

 		conf->array_sectors += rdev->sectors;
 		cnt++;

 		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 			discard_supported = true;
 	}
 	if (cnt != raid_disks) {
 		pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
 			mdname(mddev));
 		goto out;
 	}

 	if (!discard_supported)
 		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
 	else
 		blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);

 	/*
 	 * Here we calculate the device offsets.
 	 */
 	conf->disks[0].end_sector = conf->disks[0].rdev->sectors;

 	for (i = 1; i < raid_disks; i++)
 		conf->disks[i].end_sector =
 			conf->disks[i-1].end_sector +
 			conf->disks[i].rdev->sectors;

 	/*
 	 * conf->raid_disks is copy of mddev->raid_disks. The reason to
 	 * keep a copy of mddev->raid_disks in struct linear_conf is,
 	 * mddev->raid_disks may not be consistent with pointers number of
 	 * conf->disks[] when it is updated in linear_add() and used to
 	 * iterate old conf->disks[] earray in linear_congested().
 	 * Here conf->raid_disks is always consitent with number of
 	 * pointers in conf->disks[] array, and mddev->private is updated
 	 * with rcu_assign_pointer() in linear_addr(), such race can be
 	 * avoided.
 	 */
 	conf->raid_disks = raid_disks;

 	return conf;

 out:
 	kfree(conf);
 	return NULL;
 }

 static int linear_run (struct mddev *mddev)
 {
 	struct linear_conf *conf;
 	int ret;

 	if (md_check_no_bitmap(mddev))
 		return -EINVAL;
 	conf = linear_conf(mddev, mddev->raid_disks);

 	if (!conf)
 		return 1;
 	mddev->private = conf;
 	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));

 	ret =  md_integrity_register(mddev);
 	if (ret) {
 		kfree(conf);
 		mddev->private = NULL;
 	}
 	return ret;
 }

 static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
 {
 	/* Adding a drive to a linear array allows the array to grow.
 	 * It is permitted if the new drive has a matching superblock
 	 * already on it, with raid_disk equal to raid_disks.
 	 * It is achieved by creating a new linear_private_data structure
 	 * and swapping it in in-place of the current one.
 	 * The current one is never freed until the array is stopped.
 	 * This avoids races.
 	 */
 	struct linear_conf *newconf, *oldconf;

 	if (rdev->saved_raid_disk != mddev->raid_disks)
 		return -EINVAL;

 	rdev->raid_disk = rdev->saved_raid_disk;
 	rdev->saved_raid_disk = -1;

 	newconf = linear_conf(mddev,mddev->raid_disks+1);

 	if (!newconf)
 		return -ENOMEM;

 	/* newconf->raid_disks already keeps a copy of * the increased
 	 * value of mddev->raid_disks, WARN_ONCE() is just used to make
 	 * sure of this. It is possible that oldconf is still referenced
 	 * in linear_congested(), therefore kfree_rcu() is used to free
 	 * oldconf until no one uses it anymore.
 	 */
 	mddev_suspend(mddev);
 	oldconf = rcu_dereference_protected(mddev->private,
 			lockdep_is_held(&mddev->reconfig_mutex));
 	mddev->raid_disks++;
 	WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
 		"copied raid_disks doesn't match mddev->raid_disks");
 	rcu_assign_pointer(mddev->private, newconf);
 	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
 	set_capacity(mddev->gendisk, mddev->array_sectors);
 	mddev_resume(mddev);
 	revalidate_disk_size(mddev->gendisk, true);
 	kfree_rcu(oldconf, rcu);
 	return 0;
 }

 static void linear_free(struct mddev *mddev, void *priv)
 {
 	struct linear_conf *conf = priv;

 	kfree(conf);
 }

 static bool linear_make_request(struct mddev *mddev, struct bio *bio)
 {
 	char b[BDEVNAME_SIZE];
 	struct dev_info *tmp_dev;
 	sector_t start_sector, end_sector, data_offset;
 	sector_t bio_sector = bio->bi_iter.bi_sector;

 	if (unlikely(bio->bi_opf & REQ_PREFLUSH)
 	    && md_flush_request(mddev, bio))
 		return true;

 	tmp_dev = which_dev(mddev, bio_sector);
 	start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
 	end_sector = tmp_dev->end_sector;
 	data_offset = tmp_dev->rdev->data_offset;

 	if (unlikely(bio_sector >= end_sector ||
 		     bio_sector < start_sector))
 		goto out_of_bounds;

 	if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
 		bio_io_error(bio);
 		return true;
 	}

 	if (unlikely(bio_end_sector(bio) > end_sector)) {
 		/* This bio crosses a device boundary, so we have to split it */
 		struct bio *split = bio_split(bio, end_sector - bio_sector,
 					      GFP_NOIO, &mddev->bio_set);
 		bio_chain(split, bio);
 		submit_bio_noacct(bio);
 		bio = split;
 	}

 	bio_set_dev(bio, tmp_dev->rdev->bdev);
 	bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
 		start_sector + data_offset;

 	if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
 		     !blk_queue_discard(bio->bi_disk->queue))) {
 		/* Just ignore it */
 		bio_endio(bio);
 	} else {
 		if (mddev->gendisk)
 			trace_block_bio_remap(bio->bi_disk->queue,
 					      bio, disk_devt(mddev->gendisk),
 					      bio_sector);
 		mddev_check_writesame(mddev, bio);
 		mddev_check_write_zeroes(mddev, bio);
 		submit_bio_noacct(bio);
 	}
 	return true;

 out_of_bounds:
 	pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
 	       mdname(mddev),
 	       (unsigned long long)bio->bi_iter.bi_sector,
 	       bdevname(tmp_dev->rdev->bdev, b),
 	       (unsigned long long)tmp_dev->rdev->sectors,
 	       (unsigned long long)start_sector);
 	bio_io_error(bio);
 	return true;
 }

 static void linear_status (struct seq_file *seq, struct mddev *mddev)
 {
 	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
 }

 static void linear_quiesce(struct mddev *mddev, int state)
 {
 }

 static struct md_personality linear_personality =
 {
 	.name		= "linear",
 	.level		= LEVEL_LINEAR,
 	.owner		= THIS_MODULE,
 	.make_request	= linear_make_request,
 	.run		= linear_run,
 	.free		= linear_free,
 	.status		= linear_status,
 	.hot_add_disk	= linear_add,
 	.size		= linear_size,
 	.quiesce	= linear_quiesce,
 };

 static int __init linear_init (void)
 {
 	return register_md_personality (&linear_personality);
 }

 static void linear_exit (void)
 {
 	unregister_md_personality (&linear_personality);
 }

 module_init(linear_init);
 module_exit(linear_exit);
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
 MODULE_ALIAS("md-linear");
 MODULE_ALIAS("md-level--1");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	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.

	*/

	#include <linux/blkdev.h>
	#include <linux/raid/md_u.h>
	#include <linux/seq_file.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <trace/events/block.h>
	#include "md.h"
	#include "md-linear.h"

	/*
	* find which device holds a particular offset
	*/
	static inline struct dev_info which_dev(struct mddev mddev, sector_t sector)
	{
	int lo, mid, hi;
	struct linear_conf *conf;

	lo = 0;
	hi = mddev->raid_disks - 1;
	conf = mddev->private;

	/*
	* Binary Search
	*/

	while (hi > lo) {

	mid = (hi + lo) / 2;
	if (sector < conf->disks[mid].end_sector)
	hi = mid;
	else
	lo = mid + 1;
	}

	return conf->disks + lo;
	}

	static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disks)
	{
	struct linear_conf *conf;
	sector_t array_sectors;

	conf = mddev->private;
	WARN_ONCE(sectors \|\| raid_disks,
	"%s does not support generic reshape\n", __func__);
	array_sectors = conf->array_sectors;

	return array_sectors;
	}

	static struct linear_conf linear_conf(struct mddev mddev, int raid_disks)
	{
	struct linear_conf *conf;
	struct md_rdev *rdev;
	int i, cnt;
	bool discard_supported = false;

	conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
	if (!conf)
	return NULL;

	cnt = 0;
	conf->array_sectors = 0;

	rdev_for_each(rdev, mddev) {
	int j = rdev->raid_disk;
	struct dev_info *disk = conf->disks + j;
	sector_t sectors;

	if (j < 0 \|\| j >= raid_disks \|\| disk->rdev) {
	pr_warn("md/linear:%s: disk numbering problem. Aborting!\n",
	mdname(mddev));
	goto out;
	}

	disk->rdev = rdev;
	if (mddev->chunk_sectors) {
	sectors = rdev->sectors;
	sector_div(sectors, mddev->chunk_sectors);
	rdev->sectors = sectors * mddev->chunk_sectors;
	}

	disk_stack_limits(mddev->gendisk, rdev->bdev,
	rdev->data_offset << 9);

	conf->array_sectors += rdev->sectors;
	cnt++;

	if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
	discard_supported = true;
	}
	if (cnt != raid_disks) {
	pr_warn("md/linear:%s: not enough drives present. Aborting!\n",
	mdname(mddev));
	goto out;
	}

	if (!discard_supported)
	blk_queue_flag_clear(QUEUE_FLAG_DISCARD, mddev->queue);
	else
	blk_queue_flag_set(QUEUE_FLAG_DISCARD, mddev->queue);

	/*
	* Here we calculate the device offsets.
	*/
	conf->disks[0].end_sector = conf->disks[0].rdev->sectors;

	for (i = 1; i < raid_disks; i++)
	conf->disks[i].end_sector =
	conf->disks[i-1].end_sector +
	conf->disks[i].rdev->sectors;

	/*
	* conf->raid_disks is copy of mddev->raid_disks. The reason to
	* keep a copy of mddev->raid_disks in struct linear_conf is,
	* mddev->raid_disks may not be consistent with pointers number of
	* conf->disks[] when it is updated in linear_add() and used to
	* iterate old conf->disks[] earray in linear_congested().
	* Here conf->raid_disks is always consitent with number of
	* pointers in conf->disks[] array, and mddev->private is updated
	* with rcu_assign_pointer() in linear_addr(), such race can be
	* avoided.
	*/
	conf->raid_disks = raid_disks;

	return conf;

	out:
	kfree(conf);
	return NULL;
	}

	static int linear_run (struct mddev *mddev)
	{
	struct linear_conf *conf;
	int ret;

	if (md_check_no_bitmap(mddev))
	return -EINVAL;
	conf = linear_conf(mddev, mddev->raid_disks);

	if (!conf)
	return 1;
	mddev->private = conf;
	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));

	ret = md_integrity_register(mddev);
	if (ret) {
	kfree(conf);
	mddev->private = NULL;
	}
	return ret;
	}

	static int linear_add(struct mddev mddev, struct md_rdev rdev)
	{
	/* Adding a drive to a linear array allows the array to grow.
	* It is permitted if the new drive has a matching superblock
	* already on it, with raid_disk equal to raid_disks.
	* It is achieved by creating a new linear_private_data structure
	* and swapping it in in-place of the current one.
	* The current one is never freed until the array is stopped.
	* This avoids races.
	*/
	struct linear_conf newconf, oldconf;

	if (rdev->saved_raid_disk != mddev->raid_disks)
	return -EINVAL;

	rdev->raid_disk = rdev->saved_raid_disk;
	rdev->saved_raid_disk = -1;

	newconf = linear_conf(mddev,mddev->raid_disks+1);

	if (!newconf)
	return -ENOMEM;

	/* newconf->raid_disks already keeps a copy of * the increased
	* value of mddev->raid_disks, WARN_ONCE() is just used to make
	* sure of this. It is possible that oldconf is still referenced
	* in linear_congested(), therefore kfree_rcu() is used to free
	* oldconf until no one uses it anymore.
	*/
	mddev_suspend(mddev);
	oldconf = rcu_dereference_protected(mddev->private,
	lockdep_is_held(&mddev->reconfig_mutex));
	mddev->raid_disks++;
	WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
	"copied raid_disks doesn't match mddev->raid_disks");
	rcu_assign_pointer(mddev->private, newconf);
	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
	set_capacity(mddev->gendisk, mddev->array_sectors);
	mddev_resume(mddev);
	revalidate_disk_size(mddev->gendisk, true);
	kfree_rcu(oldconf, rcu);
	return 0;
	}

	static void linear_free(struct mddev mddev, void priv)
	{
	struct linear_conf *conf = priv;

	kfree(conf);
	}

	static bool linear_make_request(struct mddev mddev, struct bio bio)
	{
	char b[BDEVNAME_SIZE];
	struct dev_info *tmp_dev;
	sector_t start_sector, end_sector, data_offset;
	sector_t bio_sector = bio->bi_iter.bi_sector;

	if (unlikely(bio->bi_opf & REQ_PREFLUSH)
	&& md_flush_request(mddev, bio))
	return true;

	tmp_dev = which_dev(mddev, bio_sector);
	start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
	end_sector = tmp_dev->end_sector;
	data_offset = tmp_dev->rdev->data_offset;

	if (unlikely(bio_sector >= end_sector \|\|
	bio_sector < start_sector))
	goto out_of_bounds;

	if (unlikely(is_mddev_broken(tmp_dev->rdev, "linear"))) {
	bio_io_error(bio);
	return true;
	}

	if (unlikely(bio_end_sector(bio) > end_sector)) {
	/* This bio crosses a device boundary, so we have to split it */
	struct bio *split = bio_split(bio, end_sector - bio_sector,
	GFP_NOIO, &mddev->bio_set);
	bio_chain(split, bio);
	submit_bio_noacct(bio);
	bio = split;
	}

	bio_set_dev(bio, tmp_dev->rdev->bdev);
	bio->bi_iter.bi_sector = bio->bi_iter.bi_sector -
	start_sector + data_offset;

	if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
	!blk_queue_discard(bio->bi_disk->queue))) {
	/* Just ignore it */
	bio_endio(bio);
	} else {
	if (mddev->gendisk)
	trace_block_bio_remap(bio->bi_disk->queue,
	bio, disk_devt(mddev->gendisk),
	bio_sector);
	mddev_check_writesame(mddev, bio);
	mddev_check_write_zeroes(mddev, bio);
	submit_bio_noacct(bio);
	}
	return true;

	out_of_bounds:
	pr_err("md/linear:%s: make_request: Sector %llu out of bounds on dev %s: %llu sectors, offset %llu\n",
	mdname(mddev),
	(unsigned long long)bio->bi_iter.bi_sector,
	bdevname(tmp_dev->rdev->bdev, b),
	(unsigned long long)tmp_dev->rdev->sectors,
	(unsigned long long)start_sector);
	bio_io_error(bio);
	return true;
	}

	static void linear_status (struct seq_file seq, struct mddev mddev)
	{
	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
	}

	static void linear_quiesce(struct mddev *mddev, int state)
	{
	}

	static struct md_personality linear_personality =
	{
	.name = "linear",
	.level = LEVEL_LINEAR,
	.owner = THIS_MODULE,
	.make_request = linear_make_request,
	.run = linear_run,
	.free = linear_free,
	.status = linear_status,
	.hot_add_disk = linear_add,
	.size = linear_size,
	.quiesce = linear_quiesce,
	};

	static int __init linear_init (void)
	{
	return register_md_personality (&linear_personality);
	}

	static void linear_exit (void)
	{
	unregister_md_personality (&linear_personality);
	}

	module_init(linear_init);
	module_exit(linear_exit);
	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("Linear device concatenation personality for MD");
	MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
	MODULE_ALIAS("md-linear");
	MODULE_ALIAS("md-level--1");