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Commit 64590f45 authored by NeilBrown's avatar NeilBrown
Browse files

md: make merge_bvec_fn more robust in face of personality changes. 



There is no locking around calls to merge_bvec_fn(), so
it is possible that calls which coincide with a level (or personality)
change could go wrong.

So create a central dispatch point for these functions and use
rcu_read_lock().
If the array is suspended, reject any merge that can be rejected.
If not, we know it is safe to call the function.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 5c675f83

drivers/md/linear.c

+2 −4
Original line number Diff line number Diff line
@@ -60,11 +60,10 @@ static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector) 
 *

 *	Return amount of bytes we can take at this offset

 */

static int linear_mergeable_bvec(struct request_queue *q,

static int linear_mergeable_bvec(struct mddev *mddev,

				 struct bvec_merge_data *bvm,

				 struct bio_vec *biovec)

{

	struct mddev *mddev = q->queuedata;

	struct dev_info *dev0;

	unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;

	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
@@ -213,8 +212,6 @@ static int linear_run (struct mddev *mddev) 
	mddev->private = conf;

	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));



	blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);



	ret =  md_integrity_register(mddev);

	if (ret) {

		kfree(conf);
@@ -361,6 +358,7 @@ static struct md_personality linear_personality = 
	.hot_add_disk	= linear_add,

	.size		= linear_size,

	.congested	= linear_congested,

	.mergeable_bvec	= linear_mergeable_bvec,

};



static int __init linear_init (void)

drivers/md/md.c

+24 −0
Original line number Diff line number Diff line
@@ -339,6 +339,29 @@ static int md_congested(void *data, int bits) 
	return mddev_congested(mddev, bits);

}



static int md_mergeable_bvec(struct request_queue *q,

			     struct bvec_merge_data *bvm,

			     struct bio_vec *biovec)

{

	struct mddev *mddev = q->queuedata;

	int ret;

	rcu_read_lock();

	if (mddev->suspended) {

		/* Must always allow one vec */

		if (bvm->bi_size == 0)

			ret = biovec->bv_len;

		else

			ret = 0;

	} else {

		struct md_personality *pers = mddev->pers;

		if (pers && pers->mergeable_bvec)

			ret = pers->mergeable_bvec(mddev, bvm, biovec);

		else

			ret = biovec->bv_len;

	}

	rcu_read_unlock();

	return ret;

}

/*

 * Generic flush handling for md

 */
@@ -4925,6 +4948,7 @@ int md_run(struct mddev *mddev) 
	if (mddev->queue) {

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

		mddev->queue->backing_dev_info.congested_fn = md_congested;

		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);

	}

	if (mddev->pers->sync_request) {

		if (mddev->kobj.sd &&

drivers/md/md.h

+4 −0
Original line number Diff line number Diff line
@@ -499,6 +499,10 @@ struct md_personality 
	/* congested implements bdi.congested_fn().

	 * Will not be called while array is 'suspended' */

	int (*congested)(struct mddev *mddev, int bits);

	/* mergeable_bvec is use to implement ->merge_bvec_fn */

	int (*mergeable_bvec)(struct mddev *mddev,

			      struct bvec_merge_data *bvm,

			      struct bio_vec *biovec);

};



struct md_sysfs_entry {

drivers/md/raid0.c

+3 −4
Original line number Diff line number Diff line
@@ -350,17 +350,16 @@ static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone, 


/**

 *	raid0_mergeable_bvec -- tell bio layer if two requests can be merged

 *	@q: request queue

 *	@mddev: the md device

 *	@bvm: properties of new bio

 *	@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,

static int raid0_mergeable_bvec(struct mddev *mddev,

				struct bvec_merge_data *bvm,

				struct bio_vec *biovec)

{

	struct mddev *mddev = q->queuedata;

	struct r0conf *conf = mddev->private;

	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);

	sector_t sector_offset = sector;
@@ -465,7 +464,6 @@ static int raid0_run(struct mddev *mddev) 
			mddev->queue->backing_dev_info.ra_pages = 2* stripe;

	}



	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);

	dump_zones(mddev);



	ret = md_integrity_register(mddev);
@@ -724,6 +722,7 @@ static struct md_personality raid0_personality= 
	.takeover	= raid0_takeover,

	.quiesce	= raid0_quiesce,

	.congested	= raid0_congested,

	.mergeable_bvec	= raid0_mergeable_bvec,

};



static int __init raid0_init (void)

drivers/md/raid1.c

+2 −4
Original line number Diff line number Diff line
@@ -701,11 +701,10 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 
	return best_disk;

}



static int raid1_mergeable_bvec(struct request_queue *q,

static int raid1_mergeable_bvec(struct mddev *mddev,

				struct bvec_merge_data *bvm,

				struct bio_vec *biovec)

{

	struct mddev *mddev = q->queuedata;

	struct r1conf *conf = mddev->private;

	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);

	int max = biovec->bv_len;
@@ -2946,8 +2945,6 @@ static int run(struct mddev *mddev) 
	md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));



	if (mddev->queue) {

		blk_queue_merge_bvec(mddev->queue, raid1_mergeable_bvec);



		if (discard_supported)

			queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,

						mddev->queue);
@@ -3183,6 +3180,7 @@ static struct md_personality raid1_personality = 
	.quiesce	= raid1_quiesce,

	.takeover	= raid1_takeover,

	.congested	= raid1_congested,

	.mergeable_bvec	= raid1_mergeable_bvec,

};



static int __init raid_init(void)