}
EXPORT_SYMBOL(sg_alloc_table);
+static struct scatterlist *get_next_sg(struct sg_table *table,
+ struct scatterlist *cur,
+ unsigned long needed_sges,
+ gfp_t gfp_mask)
+{
+ struct scatterlist *new_sg, *next_sg;
+ unsigned int alloc_size;
+
+ if (cur) {
+ next_sg = sg_next(cur);
+ /* Check if last entry should be keeped for chainning */
+ if (!sg_is_last(next_sg) || needed_sges == 1)
+ return next_sg;
+ }
+
+ alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC);
+ new_sg = sg_kmalloc(alloc_size, gfp_mask);
+ if (!new_sg)
+ return ERR_PTR(-ENOMEM);
+ sg_init_table(new_sg, alloc_size);
+ if (cur) {
+ __sg_chain(next_sg, new_sg);
+ table->orig_nents += alloc_size - 1;
+ } else {
+ table->sgl = new_sg;
+ table->orig_nents = alloc_size;
+ table->nents = 0;
+ }
+ return new_sg;
+}
+
/**
* __sg_alloc_table_from_pages - Allocate and initialize an sg table from
* an array of pages
* @n_pages: Number of pages in the pages array
* @offset: Offset from start of the first page to the start of a buffer
* @size: Number of valid bytes in the buffer (after offset)
- * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
+ * @max_segment: Maximum size of a scatterlist element in bytes
+ * @prv: Last populated sge in sgt
+ * @left_pages: Left pages caller have to set after this call
* @gfp_mask: GFP allocation mask
*
- * Description:
- * Allocate and initialize an sg table from a list of pages. Contiguous
- * ranges of the pages are squashed into a single scatterlist node up to the
- * maximum size specified in @max_segment. An user may provide an offset at a
- * start and a size of valid data in a buffer specified by the page array.
- * The returned sg table is released by sg_free_table.
+ * Description:
+ * If @prv is NULL, allocate and initialize an sg table from a list of pages,
+ * else reuse the scatterlist passed in at @prv.
+ * Contiguous ranges of the pages are squashed into a single scatterlist
+ * entry up to the maximum size specified in @max_segment. A user may
+ * provide an offset at a start and a size of valid data in a buffer
+ * specified by the page array.
*
* Returns:
- * 0 on success, negative error on failure
+ * Last SGE in sgt on success, PTR_ERR on otherwise.
+ * The allocation in @sgt must be released by sg_free_table.
+ *
+ * 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_from_pages(struct sg_table *sgt, struct page **pages,
- unsigned int n_pages, unsigned int offset,
- unsigned long size, unsigned int max_segment,
- gfp_t gfp_mask)
+struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt,
+ struct page **pages, unsigned int n_pages, unsigned int offset,
+ unsigned long size, unsigned int max_segment,
+ struct scatterlist *prv, unsigned int left_pages,
+ gfp_t gfp_mask)
{
- unsigned int chunks, cur_page, seg_len, i;
- int ret;
- struct scatterlist *s;
+ unsigned int chunks, cur_page, seg_len, i, prv_len = 0;
+ unsigned int added_nents = 0;
+ struct scatterlist *s = prv;
- if (WARN_ON(!max_segment || offset_in_page(max_segment)))
- return -EINVAL;
+ /*
+ * The algorithm below requires max_segment to be aligned to PAGE_SIZE
+ * otherwise it can overshoot.
+ */
+ max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE);
+ if (WARN_ON(max_segment < PAGE_SIZE))
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && prv)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ if (prv) {
+ unsigned long paddr = (page_to_pfn(sg_page(prv)) * PAGE_SIZE +
+ prv->offset + prv->length) /
+ PAGE_SIZE;
+
+ if (WARN_ON(offset))
+ return ERR_PTR(-EINVAL);
+
+ /* Merge contiguous pages into the last SG */
+ prv_len = prv->length;
+ while (n_pages && page_to_pfn(pages[0]) == paddr) {
+ if (prv->length + PAGE_SIZE > max_segment)
+ break;
+ prv->length += PAGE_SIZE;
+ paddr++;
+ pages++;
+ n_pages--;
+ }
+ if (!n_pages)
+ goto out;
+ }
/* compute number of contiguous chunks */
chunks = 1;
}
}
- ret = sg_alloc_table(sgt, chunks, gfp_mask);
- if (unlikely(ret))
- return ret;
-
/* merging chunks and putting them into the scatterlist */
cur_page = 0;
- for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
+ for (i = 0; i < chunks; i++) {
unsigned int j, chunk_size;
/* look for the end of the current chunk */
break;
}
+ /* Pass how many chunks might be left */
+ s = get_next_sg(sgt, s, chunks - i + left_pages, gfp_mask);
+ if (IS_ERR(s)) {
+ /*
+ * Adjust entry length to be as before function was
+ * called.
+ */
+ if (prv)
+ prv->length = prv_len;
+ return s;
+ }
chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
sg_set_page(s, pages[cur_page],
min_t(unsigned long, size, chunk_size), offset);
+ added_nents++;
size -= chunk_size;
offset = 0;
cur_page = j;
}
-
- return 0;
+ sgt->nents += added_nents;
+out:
+ if (!left_pages)
+ sg_mark_end(s);
+ return s;
}
EXPORT_SYMBOL(__sg_alloc_table_from_pages);
unsigned int n_pages, unsigned int offset,
unsigned long size, gfp_t gfp_mask)
{
- return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
- SCATTERLIST_MAX_SEGMENT, gfp_mask);
+ return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages,
+ offset, size, UINT_MAX, NULL, 0, gfp_mask));
}
EXPORT_SYMBOL(sg_alloc_table_from_pages);
elem_len = min_t(u64, length, PAGE_SIZE << order);
page = alloc_pages(gfp, order);
if (!page) {
- sgl_free(sgl);
+ sgl_free_order(sgl, order);
return NULL;
}
sg_miter_start(&miter, sgl, nents, sg_flags);
if (!sg_miter_skip(&miter, skip))
- return false;
+ return 0;
while ((offset < buflen) && sg_miter_next(&miter)) {
unsigned int len;
projects / linux-2.6-microblaze.git / blobdiff