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Commit 17be8c24 authored by Martin K. Petersen's avatar Martin K. Petersen Committed by Jens Axboe
Browse files

block: bdev_stack_limits wrapper 



DM does not want to know about partition offsets.  Add a partition-aware
wrapper that DM can use when stacking block devices.

Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Reviewed-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent dd3d145d

block/blk-settings.c

+22 −0
Original line number Diff line number Diff line
@@ -639,6 +639,28 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 
}

EXPORT_SYMBOL(blk_stack_limits);



/**

 * bdev_stack_limits - adjust queue limits for stacked drivers

 * @t:	the stacking driver limits (top device)

 * @bdev:  the component block_device (bottom)

 * @start:  first data sector within component device

 *

 * Description:

 *    Merges queue limits for a top device and a block_device.  Returns

 *    0 if alignment didn't change.  Returns -1 if adding the bottom

 *    device caused misalignment.

 */

int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,

		      sector_t start)

{

	struct request_queue *bq = bdev_get_queue(bdev);



	start += get_start_sect(bdev);



	return blk_stack_limits(t, &bq->limits, start << 9);

}

EXPORT_SYMBOL(bdev_stack_limits);



/**

 * disk_stack_limits - adjust queue limits for stacked drivers

 * @disk:  MD/DM gendisk (top)

include/linux/blkdev.h

+2 −0
Original line number Diff line number Diff line
@@ -938,6 +938,8 @@ extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt); 
extern void blk_set_default_limits(struct queue_limits *lim);

extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,

			    sector_t offset);

extern int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev,

			    sector_t offset);

extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,

			      sector_t offset);

extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);