X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=lib%2Fscatterlist.c;h=c2cf2c311b7dba0b055da1bca59bbca20d340420;hb=bfc7931c40908a3e5575c527754ef4be2e24c83b;hp=2882d9ba6607a71490f994518d16bae4e59a16e5;hpb=c39f2d9db0fd81ea20bb5cce9b3f082ca63753e2;p=linux.git

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 2882d9ba6607..c2cf2c311b7d 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -179,7 +179,8 @@ static void sg_kfree(struct scatterlist *sg, unsigned int nents)
  * __sg_free_table - Free a previously mapped sg table
  * @table:	The sg table header to use
  * @max_ents:	The maximum number of entries per single scatterlist
- * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
+ * @nents_first_chunk: Number of entries int the (preallocated) first
+ * 	scatterlist chunk, 0 means no such preallocated first chunk
  * @free_fn:	Free function
  *
  *  Description:
@@ -189,9 +190,10 @@ static void sg_kfree(struct scatterlist *sg, unsigned int nents)
  *
  **/
 void __sg_free_table(struct sg_table *table, unsigned int max_ents,
-		     bool skip_first_chunk, sg_free_fn *free_fn)
+		     unsigned int nents_first_chunk, sg_free_fn *free_fn)
 {
 	struct scatterlist *sgl, *next;
+	unsigned curr_max_ents = nents_first_chunk ?: max_ents;
 
 	if (unlikely(!table->sgl))
 		return;
@@ -207,9 +209,9 @@ void __sg_free_table(struct sg_table *table, unsigned int max_ents,
 		 * sg_size is then one less than alloc size, since the last
 		 * element is the chain pointer.
 		 */
-		if (alloc_size > max_ents) {
-			next = sg_chain_ptr(&sgl[max_ents - 1]);
-			alloc_size = max_ents;
+		if (alloc_size > curr_max_ents) {
+			next = sg_chain_ptr(&sgl[curr_max_ents - 1]);
+			alloc_size = curr_max_ents;
 			sg_size = alloc_size - 1;
 		} else {
 			sg_size = alloc_size;
@@ -217,11 +219,12 @@ void __sg_free_table(struct sg_table *table, unsigned int max_ents,
 		}
 
 		table->orig_nents -= sg_size;
-		if (skip_first_chunk)
-			skip_first_chunk = false;
+		if (nents_first_chunk)
+			nents_first_chunk = 0;
 		else
 			free_fn(sgl, alloc_size);
 		sgl = next;
+		curr_max_ents = max_ents;
 	}
 
 	table->sgl = NULL;
@@ -244,6 +247,8 @@ EXPORT_SYMBOL(sg_free_table);
  * @table:	The sg table header to use
  * @nents:	Number of entries in sg list
  * @max_ents:	The maximum number of entries the allocator returns per call
+ * @nents_first_chunk: Number of entries int the (preallocated) first
+ * 	scatterlist chunk, 0 means no such preallocated chunk provided by user
  * @gfp_mask:	GFP allocation mask
  * @alloc_fn:	Allocator to use
  *
@@ -260,10 +265,13 @@ EXPORT_SYMBOL(sg_free_table);
  **/
 int __sg_alloc_table(struct sg_table *table, unsigned int nents,
 		     unsigned int max_ents, struct scatterlist *first_chunk,
-		     gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
+		     unsigned int nents_first_chunk, gfp_t gfp_mask,
+		     sg_alloc_fn *alloc_fn)
 {
 	struct scatterlist *sg, *prv;
 	unsigned int left;
+	unsigned curr_max_ents = nents_first_chunk ?: max_ents;
+	unsigned prv_max_ents;
 
 	memset(table, 0, sizeof(*table));
 
@@ -279,8 +287,8 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
 	do {
 		unsigned int sg_size, alloc_size = left;
 
-		if (alloc_size > max_ents) {
-			alloc_size = max_ents;
+		if (alloc_size > curr_max_ents) {
+			alloc_size = curr_max_ents;
 			sg_size = alloc_size - 1;
 		} else
 			sg_size = alloc_size;
@@ -314,7 +322,7 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
 		 * If this is not the first mapping, chain previous part.
 		 */
 		if (prv)
-			sg_chain(prv, max_ents, sg);
+			sg_chain(prv, prv_max_ents, sg);
 		else
 			table->sgl = sg;
 
@@ -325,6 +333,8 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
 			sg_mark_end(&sg[sg_size - 1]);
 
 		prv = sg;
+		prv_max_ents = curr_max_ents;
+		curr_max_ents = max_ents;
 	} while (left);
 
 	return 0;
@@ -347,9 +357,9 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
 	int ret;
 
 	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
-			       NULL, gfp_mask, sg_kmalloc);
+			       NULL, 0, gfp_mask, sg_kmalloc);
 	if (unlikely(ret))
-		__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
+		__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
 
 	return ret;
 }
@@ -676,17 +686,18 @@ static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
 {
 	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->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset;
+		miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT;
+		miter->__offset &= PAGE_SIZE - 1;
 		miter->__remaining = sg->offset + sg->length -
-				(pgoffset << PAGE_SHIFT) - miter->__offset;
+				     (miter->piter.sg_pgoffset << PAGE_SHIFT) -
+				     miter->__offset;
 		miter->__remaining = min_t(unsigned long, miter->__remaining,
 					   PAGE_SIZE - miter->__offset);
 	}