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authorImre Deak <imre.deak@intel.com>2013-02-27 17:02:57 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 19:10:10 -0800
commit4225fc8555a992c7f91d174ef424384d6781e144 (patch)
tree46f73428afef93acc729fd36842e463b503bab58
parenta321e91b6d73ed011ffceed384c40d2785cf723b (diff)
downloadop-kernel-dev-4225fc8555a992c7f91d174ef424384d6781e144.zip
op-kernel-dev-4225fc8555a992c7f91d174ef424384d6781e144.tar.gz
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: Imre 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/mmc/host/dw_mmc.c4
-rw-r--r--include/linux/scatterlist.h6
-rw-r--r--lib/scatterlist.c48
3 files changed, 28 insertions, 30 deletions
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 60063cc..9834221 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -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;
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 788a853..2d8bdae 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -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;
};
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index a1d1564..b83c144 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -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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