Merge iov-extract-base onto cifs/for-next

Merge the two commits to provide iov_iter_extract_pages() onto the for-next
branch of git.samba.org/sfrench/cifs-2.6.git to use as a base for my
iteratorisation-of-cifs patches.

Signed-off-by: David Howells <dhowells@redhat.com>

block/bio.c

@@ -1245,11 +1245,11 @@ static int bio_iov_add_zone_append_page(struct bio *bio, struct page *page,
  */
 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
+	iov_iter_extraction_t extraction_flags = 0;
 	unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
 	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
 	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
 	struct page **pages = (struct page **)bv;
-	unsigned int gup_flags = 0;
 	ssize_t size, left;
 	unsigned len, i = 0;
 	size_t offset, trim;
@@ -1264,7 +1264,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
 
 	if (bio->bi_bdev && blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
-		gup_flags |= FOLL_PCI_P2PDMA;
+		extraction_flags |= ITER_ALLOW_P2PDMA;
 
 	/*
 	 * Each segment in the iov is required to be a block size multiple.
@@ -1275,7 +1275,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	 */
 	size = iov_iter_get_pages(iter, pages,
 				  UINT_MAX - bio->bi_iter.bi_size,
-				  nr_pages, &offset, gup_flags);
+				  nr_pages, &offset, extraction_flags);
 	if (unlikely(size <= 0))
 		return size ? size : -EFAULT;
 

block/blk-map.c

@@ -265,9 +265,9 @@ static struct bio *blk_rq_map_bio_alloc(struct request *rq,
 static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		gfp_t gfp_mask)
 {
+	iov_iter_extraction_t extraction_flags = 0;
 	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
 	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
-	unsigned int gup_flags = 0;
 	struct bio *bio;
 	int ret;
 	int j;
@@ -280,7 +280,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		return -ENOMEM;
 
 	if (blk_queue_pci_p2pdma(rq->q))
-		gup_flags |= FOLL_PCI_P2PDMA;
+		extraction_flags |= ITER_ALLOW_P2PDMA;
 
 	while (iov_iter_count(iter)) {
 		struct page **pages, *stack_pages[UIO_FASTIOV];
@@ -291,10 +291,10 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		if (nr_vecs <= ARRAY_SIZE(stack_pages)) {
 			pages = stack_pages;
 			bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
-						   nr_vecs, &offs, gup_flags);
+						   nr_vecs, &offs, extraction_flags);
 		} else {
 			bytes = iov_iter_get_pages_alloc(iter, &pages,
-						LONG_MAX, &offs, gup_flags);
+						LONG_MAX, &offs, extraction_flags);
 		}
 		if (unlikely(bytes <= 0)) {
 			ret = bytes ? bytes : -EFAULT;

include/linux/uio.h

@@ -13,6 +13,8 @@
 struct page;
 struct pipe_inode_info;
 
+typedef unsigned int __bitwise iov_iter_extraction_t;
+
 struct kvec {
 	void *iov_base; /* and that should *never* hold a userland pointer */
 	size_t iov_len;
@@ -252,12 +254,12 @@ void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *
 		     loff_t start, size_t count);
 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 		size_t maxsize, unsigned maxpages, size_t *start,
-		unsigned gup_flags);
+		iov_iter_extraction_t extraction_flags);
 ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
 			size_t maxsize, unsigned maxpages, size_t *start);
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		struct page ***pages, size_t maxsize, size_t *start,
-		unsigned gup_flags);
+		iov_iter_extraction_t extraction_flags);
 ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
 			size_t maxsize, size_t *start);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);
@@ -359,5 +361,34 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 		.count = count
 	};
 }
+/* Flags for iov_iter_get/extract_pages*() */
+/* Allow P2PDMA on the extracted pages */
+#define ITER_ALLOW_P2PDMA	((__force iov_iter_extraction_t)0x01)
+
+ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,
+			       size_t maxsize, unsigned int maxpages,
+			       iov_iter_extraction_t extraction_flags,
+			       size_t *offset0);
+
+/**
+ * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained
+ * @iter: The iterator
+ *
+ * Examine the iterator and indicate by returning true or false as to how, if
+ * at all, pages extracted from the iterator will be retained by the extraction
+ * function.
+ *
+ * %true indicates that the pages will have a pin placed in them that the
+ * caller must unpin.  This is must be done for DMA/async DIO to force fork()
+ * to forcibly copy a page for the child (the parent must retain the original
+ * page).
+ *
+ * %false indicates that no measures are taken and that it's up to the caller
+ * to retain the pages.
+ */
+static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter)
+{
+	return user_backed_iter(iter);
+}
 
 #endif