lib/scatterlist: Add SG_MITER_LOCAL and use it

Add kmap_local support to the scatterlist iterator.  Use it for
all the helper functions in lib/scatterlist.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index d836e7440ee863539e0422b789986d025962858c..138e2f1bd08f2df20312fd35948626fec946bb36 100644 (file)
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -671,6 +671,7 @@ sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
 #define SG_MITER_ATOMIC                (1 << 0)         /* use kmap_atomic */
 #define SG_MITER_TO_SG         (1 << 1)        /* flush back to phys on unmap */
 #define SG_MITER_FROM_SG       (1 << 2)        /* nop */
+#define SG_MITER_LOCAL         (1 << 3)         /* use kmap_local */
 
 struct sg_mapping_iter {
        /* the following three fields can be accessed directly */

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 5bb6b8aff2325640057192111f36367247033e34..b58d5ef1a34b07c8aa015f54d72d190c8c1ad5e6 100644 (file)
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -879,7 +879,7 @@ EXPORT_SYMBOL(sg_miter_skip);
  *   @miter->addr and @miter->length point to the current mapping.
  *
  * Context:
- *   May sleep if !SG_MITER_ATOMIC.
+ *   May sleep if !SG_MITER_ATOMIC && !SG_MITER_LOCAL.
  *
  * Returns:
  *   true if @miter contains the next mapping.  false if end of sg
@@ -901,6 +901,8 @@ bool sg_miter_next(struct sg_mapping_iter *miter)
 
        if (miter->__flags & SG_MITER_ATOMIC)
                miter->addr = kmap_atomic(miter->page) + miter->__offset;
+       else if (miter->__flags & SG_MITER_LOCAL)
+               miter->addr = kmap_local_page(miter->page) + miter->__offset;
        else
                miter->addr = kmap(miter->page) + miter->__offset;
 
@@ -936,7 +938,9 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
                if (miter->__flags & SG_MITER_ATOMIC) {
                        WARN_ON_ONCE(!pagefault_disabled());
                        kunmap_atomic(miter->addr);
-               } else
+               } else if (miter->__flags & SG_MITER_LOCAL)
+                       kunmap_local(miter->addr);
+               else
                        kunmap(miter->page);
 
                miter->page = NULL;
@@ -965,7 +969,7 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
 {
        unsigned int offset = 0;
        struct sg_mapping_iter miter;
-       unsigned int sg_flags = SG_MITER_ATOMIC;
+       unsigned int sg_flags = SG_MITER_LOCAL;
 
        if (to_buffer)
                sg_flags |= SG_MITER_FROM_SG;
@@ -1080,7 +1084,7 @@ size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
 {
        unsigned int offset = 0;
        struct sg_mapping_iter miter;
-       unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
+       unsigned int sg_flags = SG_MITER_LOCAL | SG_MITER_TO_SG;
 
        sg_miter_start(&miter, sgl, nents, sg_flags);