3 files changed, 28 insertions, 30 deletions

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 60063ccb4c4b..98342213ed21 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 788a853aa7a7..2d8bdaef9611 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 a1d15647d7db..b83c144d731f 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);