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block, bdi: an active gendisk always has a request_queue associated with it

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bdev_get_queue() returns the request_queue associated with the
specified block_device.  blk_get_backing_dev_info() makes use of
bdev_get_queue() to determine the associated bdi given a block_device.

All the callers of bdev_get_queue() including
blk_get_backing_dev_info() assume that bdev_get_queue() may return
NULL and implement NULL handling; however, bdev_get_queue() requires
the passed in block_device is opened and attached to its gendisk.
Because an active gendisk always has a valid request_queue associated
with it, bdev_get_queue() can never return NULL and neither can
blk_get_backing_dev_info().

Make it clear that neither of the two functions can return NULL and
remove NULL handling from all the callers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2014-09-08 08:03:56 +09:00 • committed by Jens Axboe
parent f4da80727c
commit ff9ea32381
7 changed files with 5 additions and 21 deletions
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2
include/linux/blkdev.h
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@ -865,7 +865,7 @@ extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
{
return bdev->bd_disk->queue;
return bdev->bd_disk->queue; /* this is never NULL */
}
/*