*/
#include <linux/module.h>
#include <linux/scatterlist.h>
+#include <linux/highmem.h>
/**
* sg_next - return the next scatterlist entry in a list
/**
* __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
* @free_fn: Free function
*
* Description:
- * Free an sg table previously allocated and setup with __sg_alloc_table().
+ * Free an sg table previously allocated and setup with
+ * __sg_alloc_table(). The @max_ents value must be identical to
+ * that previously used with __sg_alloc_table().
*
**/
-void __sg_free_table(struct sg_table *table, sg_free_fn *free_fn)
+void __sg_free_table(struct sg_table *table, unsigned int max_ents,
+ sg_free_fn *free_fn)
{
struct scatterlist *sgl, *next;
unsigned int sg_size;
/*
- * If we have more than SG_MAX_SINGLE_ALLOC segments left,
+ * If we have more than max_ents segments left,
* then assign 'next' to the sg table after the current one.
* sg_size is then one less than alloc size, since the last
* element is the chain pointer.
*/
- if (alloc_size > SG_MAX_SINGLE_ALLOC) {
- next = sg_chain_ptr(&sgl[SG_MAX_SINGLE_ALLOC - 1]);
- alloc_size = SG_MAX_SINGLE_ALLOC;
+ if (alloc_size > max_ents) {
+ next = sg_chain_ptr(&sgl[max_ents - 1]);
+ alloc_size = max_ents;
sg_size = alloc_size - 1;
} else {
sg_size = alloc_size;
**/
void sg_free_table(struct sg_table *table)
{
- __sg_free_table(table, sg_kfree);
+ __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
}
EXPORT_SYMBOL(sg_free_table);
* __sg_alloc_table - Allocate and initialize an sg table with given allocator
* @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
* @gfp_mask: GFP allocation mask
* @alloc_fn: Allocator to use
*
+ * Description:
+ * This function returns a @table @nents long. The allocator is
+ * defined to return scatterlist chunks of maximum size @max_ents.
+ * Thus if @nents is bigger than @max_ents, the scatterlists will be
+ * chained in units of @max_ents.
+ *
* Notes:
* If this function returns non-0 (eg failure), the caller must call
* __sg_free_table() to cleanup any leftover allocations.
*
**/
-int __sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask,
+int __sg_alloc_table(struct sg_table *table, unsigned int nents,
+ unsigned int max_ents, gfp_t gfp_mask,
sg_alloc_fn *alloc_fn)
{
struct scatterlist *sg, *prv;
unsigned int left;
#ifndef ARCH_HAS_SG_CHAIN
- BUG_ON(nents > SG_MAX_SINGLE_ALLOC);
+ BUG_ON(nents > max_ents);
#endif
memset(table, 0, sizeof(*table));
do {
unsigned int sg_size, alloc_size = left;
- if (alloc_size > SG_MAX_SINGLE_ALLOC) {
- alloc_size = SG_MAX_SINGLE_ALLOC;
+ if (alloc_size > max_ents) {
+ alloc_size = max_ents;
sg_size = alloc_size - 1;
} else
sg_size = alloc_size;
* If this is not the first mapping, chain previous part.
*/
if (prv)
- sg_chain(prv, SG_MAX_SINGLE_ALLOC, sg);
+ sg_chain(prv, max_ents, sg);
else
table->sgl = sg;
{
int ret;
- ret = __sg_alloc_table(table, nents, gfp_mask, sg_kmalloc);
+ ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
+ gfp_mask, sg_kmalloc);
if (unlikely(ret))
- __sg_free_table(table, sg_kfree);
+ __sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
return ret;
}
EXPORT_SYMBOL(sg_alloc_table);
+
+/**
+ * sg_copy_buffer - Copy data between a linear buffer and an SG list
+ * @sgl: The SG list
+ * @nents: Number of SG entries
+ * @buf: Where to copy from
+ * @buflen: The number of bytes to copy
+ * @to_buffer: transfer direction (non zero == from an sg list to a
+ * buffer, 0 == from a buffer to an sg list
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, int to_buffer)
+{
+ struct scatterlist *sg;
+ size_t buf_off = 0;
+ int i;
+
+ WARN_ON(!irqs_disabled());
+
+ for_each_sg(sgl, sg, nents, i) {
+ struct page *page;
+ int n = 0;
+ unsigned int sg_off = sg->offset;
+ unsigned int sg_copy = sg->length;
+
+ if (sg_copy > buflen)
+ sg_copy = buflen;
+ buflen -= sg_copy;
+
+ while (sg_copy > 0) {
+ unsigned int page_copy;
+ void *p;
+
+ page_copy = PAGE_SIZE - sg_off;
+ if (page_copy > sg_copy)
+ page_copy = sg_copy;
+
+ page = nth_page(sg_page(sg), n);
+ p = kmap_atomic(page, KM_BIO_SRC_IRQ);
+
+ if (to_buffer)
+ memcpy(buf + buf_off, p + sg_off, page_copy);
+ else {
+ memcpy(p + sg_off, buf + buf_off, page_copy);
+ flush_kernel_dcache_page(page);
+ }
+
+ kunmap_atomic(p, KM_BIO_SRC_IRQ);
+
+ buf_off += page_copy;
+ sg_off += page_copy;
+ if (sg_off == PAGE_SIZE) {
+ sg_off = 0;
+ n++;
+ }
+ sg_copy -= page_copy;
+ }
+
+ if (!buflen)
+ break;
+ }
+
+ return buf_off;
+}
+
+/**
+ * sg_copy_from_buffer - Copy from a linear buffer to an SG list
+ * @sgl: The SG list
+ * @nents: Number of SG entries
+ * @buf: Where to copy from
+ * @buflen: The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, 0);
+}
+EXPORT_SYMBOL(sg_copy_from_buffer);
+
+/**
+ * sg_copy_to_buffer - Copy from an SG list to a linear buffer
+ * @sgl: The SG list
+ * @nents: Number of SG entries
+ * @buf: Where to copy to
+ * @buflen: The number of bytes to copy
+ *
+ * Returns the number of copied bytes.
+ *
+ **/
+size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, 1);
+}
+EXPORT_SYMBOL(sg_copy_to_buffer);