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Commit 2e484610 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Jens Axboe
Browse files

scatterlist: add sg_nents 



Useful helper to know the number of entries in scatterlist.

Signed-off-by: default avatarMaxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c2b1ad80

include/linux/scatterlist.h

+1 −0
Original line number Diff line number Diff line
@@ -201,6 +201,7 @@ static inline void *sg_virt(struct scatterlist *sg) 
	return page_address(sg_page(sg)) + sg->offset;

}



int sg_nents(struct scatterlist *sg);

struct scatterlist *sg_next(struct scatterlist *);

struct scatterlist *sg_last(struct scatterlist *s, unsigned int);

void sg_init_table(struct scatterlist *, unsigned int);

lib/scatterlist.c

+22 −0
Original line number Diff line number Diff line
@@ -38,6 +38,28 @@ struct scatterlist *sg_next(struct scatterlist *sg) 
}

EXPORT_SYMBOL(sg_next);



/**

 * sg_nents - return total count of entries in scatterlist

 * @sg:		The scatterlist

 *

 * Description:

 * Allows to know how many entries are in sg, taking into acount

 * chaining as well

 *

 **/

int sg_nents(struct scatterlist *sg)

{

	int nents = 0;

	while (sg) {

		nents++;

		sg = sg_next(sg);

	}



	return nents;

}

EXPORT_SYMBOL(sg_nents);





/**

 * sg_last - return the last scatterlist entry in a list

 * @sgl:	First entry in the scatterlist