Commit 4225fc85 authored by Imre Deak's avatar Imre Deak Committed by Linus Torvalds
Browse files

lib/scatterlist: use page iterator in the mapping iterator 



For better code reuse use the newly added page iterator to iterate
through the pages.  The offset, length within the page is still
calculated by the mapping iterator as well as the actual mapping.  Idea
from Tejun Heo.

Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a321e91b

drivers/mmc/host/dw_mmc.c

+2 −2
Original line number Diff line number Diff line
@@ -1453,7 +1453,7 @@ static void dw_mci_read_data_pio(struct dw_mci *host) 
		if (!sg_miter_next(sg_miter))

			goto done;



		host->sg = sg_miter->__sg;

		host->sg = sg_miter->piter.sg;

		buf = sg_miter->addr;

		remain = sg_miter->length;

		offset = 0;
@@ -1508,7 +1508,7 @@ static void dw_mci_write_data_pio(struct dw_mci *host) 
		if (!sg_miter_next(sg_miter))

			goto done;



		host->sg = sg_miter->__sg;

		host->sg = sg_miter->piter.sg;

		buf = sg_miter->addr;

		remain = sg_miter->length;

		offset = 0;

include/linux/scatterlist.h

+3 −3
Original line number Diff line number Diff line
@@ -293,11 +293,11 @@ struct sg_mapping_iter { 
	void			*addr;		/* pointer to the mapped area */

	size_t			length;		/* length of the mapped area */

	size_t			consumed;	/* number of consumed bytes */

	struct sg_page_iter	piter;		/* page iterator */



	/* these are internal states, keep away */

	struct scatterlist	*__sg;		/* current entry */

	unsigned int		__nents;	/* nr of remaining entries */

	unsigned int		__offset;	/* offset within sg */

	unsigned int		__offset;	/* offset within page */

	unsigned int		__remaining;	/* remaining bytes on page */

	unsigned int		__flags;

};

lib/scatterlist.c

+23 −25
Original line number Diff line number Diff line
@@ -449,9 +449,7 @@ void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, 
{

	memset(miter, 0, sizeof(struct sg_mapping_iter));



	miter->__sg = sgl;

	miter->__nents = nents;

	miter->__offset = 0;

	__sg_page_iter_start(&miter->piter, sgl, nents, 0);

	WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));

	miter->__flags = flags;

}
@@ -476,36 +474,35 @@ EXPORT_SYMBOL(sg_miter_start); 
 */

bool sg_miter_next(struct sg_mapping_iter *miter)

{

	unsigned int off, len;



	/* check for end and drop resources from the last iteration */

	if (!miter->__nents)

		return false;



	sg_miter_stop(miter);



	/* get to the next sg if necessary.  __offset is adjusted by stop */

	while (miter->__offset == miter->__sg->length) {

		if (--miter->__nents) {

			miter->__sg = sg_next(miter->__sg);

			miter->__offset = 0;

		} else

	/*

	 * Get to the next page if necessary.

	 * __remaining, __offset is adjusted by sg_miter_stop

	 */

	if (!miter->__remaining) {

		struct scatterlist *sg;

		unsigned long pgoffset;



		if (!__sg_page_iter_next(&miter->piter))

			return false;

	}



	/* map the next page */

	off = miter->__sg->offset + miter->__offset;

	len = miter->__sg->length - miter->__offset;

		sg = miter->piter.sg;

		pgoffset = miter->piter.sg_pgoffset;



	miter->page = nth_page(sg_page(miter->__sg), off >> PAGE_SHIFT);

	off &= ~PAGE_MASK;

	miter->length = min_t(unsigned int, len, PAGE_SIZE - off);

	miter->consumed = miter->length;

		miter->__offset = pgoffset ? 0 : sg->offset;

		miter->__remaining = sg->offset + sg->length -

				(pgoffset << PAGE_SHIFT) - miter->__offset;

		miter->__remaining = min_t(unsigned long, miter->__remaining,

					   PAGE_SIZE - miter->__offset);

	}

	miter->page = miter->piter.page;

	miter->consumed = miter->length = miter->__remaining;



	if (miter->__flags & SG_MITER_ATOMIC)

		miter->addr = kmap_atomic(miter->page) + off;

		miter->addr = kmap_atomic(miter->page) + miter->__offset;

	else

		miter->addr = kmap(miter->page) + off;

		miter->addr = kmap(miter->page) + miter->__offset;



	return true;

}
@@ -532,6 +529,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter) 
	/* drop resources from the last iteration */

	if (miter->addr) {

		miter->__offset += miter->consumed;

		miter->__remaining -= miter->consumed;



		if (miter->__flags & SG_MITER_TO_SG)

			flush_kernel_dcache_page(miter->page);

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