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>
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 @@
{
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 @@
*/
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;
+
+ sg = miter->piter.sg;
+ pgoffset = miter->piter.sg_pgoffset;
+
+ 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);
}
-
- /* map the next page */
- off = miter->__sg->offset + miter->__offset;
- len = miter->__sg->length - miter->__offset;
-
- 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->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 @@
/* 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);