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Commit c8164d89 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Rusty Russell
Browse files

scatterlist: introduce sg_unmark_end 



This is useful in places that recycle the same scatterlist multiple
times, and do not want to incur the cost of sg_init_table every
time in hot paths.

Acked-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 0d2e1a29

block/blk-integrity.c

+1 −1
Original line number Diff line number Diff line
@@ -110,7 +110,7 @@ int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio, 
			if (!sg)

				sg = sglist;

			else {

				sg->page_link &= ~0x02;

				sg_unmark_end(sg);

				sg = sg_next(sg);

			}

block/blk-merge.c

+1 −1
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, 
			 * termination bit to avoid doing a full

			 * sg_init_table() in drivers for each command.

			 */

			(*sg)->page_link &= ~0x02;

			sg_unmark_end(*sg);

			*sg = sg_next(*sg);

		}

include/linux/scatterlist.h

+16 −0
Original line number Diff line number Diff line
@@ -171,6 +171,22 @@ static inline void sg_mark_end(struct scatterlist *sg) 
	sg->page_link &= ~0x01;

}



/**

 * sg_unmark_end - Undo setting the end of the scatterlist

 * @sg:		 SG entryScatterlist

 *

 * Description:

 *   Removes the termination marker from the given entry of the scatterlist.

 *

 **/

static inline void sg_unmark_end(struct scatterlist *sg)

{

#ifdef CONFIG_DEBUG_SG

	BUG_ON(sg->sg_magic != SG_MAGIC);

#endif

	sg->page_link &= ~0x02;

}



/**

 * sg_phys - Return physical address of an sg entry

 * @sg:	     SG entry