diff options
Diffstat (limited to 'lib/scatterlist.c')
| -rw-r--r-- | lib/scatterlist.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 7874b01e816e..a1d15647d7db 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -394,6 +394,44 @@ int sg_alloc_table_from_pages(struct sg_table *sgt, } EXPORT_SYMBOL(sg_alloc_table_from_pages); +void __sg_page_iter_start(struct sg_page_iter *piter, + struct scatterlist *sglist, unsigned int nents, + unsigned long pgoffset) +{ + piter->__pg_advance = 0; + piter->__nents = nents; + + piter->page = NULL; + piter->sg = sglist; + piter->sg_pgoffset = pgoffset; +} +EXPORT_SYMBOL(__sg_page_iter_start); + +static int sg_page_count(struct scatterlist *sg) +{ + return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; +} + +bool __sg_page_iter_next(struct sg_page_iter *piter) +{ + if (!piter->__nents || !piter->sg) + return false; + + piter->sg_pgoffset += piter->__pg_advance; + piter->__pg_advance = 1; + + while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { + piter->sg_pgoffset -= sg_page_count(piter->sg); + piter->sg = sg_next(piter->sg); + if (!--piter->__nents || !piter->sg) + return false; + } + piter->page = nth_page(sg_page(piter->sg), piter->sg_pgoffset); + + return true; +} +EXPORT_SYMBOL(__sg_page_iter_next); + /** * sg_miter_start - start mapping iteration over a sg list * @miter: sg mapping iter to be started |