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block: bdev_stack_limits wrapper

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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: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Martin K. Petersen 2010-01-11 03:21:49 -05:00 committed by Jens Axboe
parent dd3d145d49
commit 17be8c2450
2 changed files with 24 additions and 0 deletions
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22
block/blk-settings.c
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@ -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)

2
include/linux/blkdev.h
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@ -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);