switch iov_iter_get_pages() to passing maximal number of pages

... instead of maximal size.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/direct-io.c

@@ -158,7 +158,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 {
 	ssize_t ret;
 
-	ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES * PAGE_SIZE,
+	ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES,
 				&sdio->from);
 
 	if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {

fs/fuse/file.c

@@ -1303,10 +1303,10 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
 	while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
 		unsigned npages;
 		size_t start;
-		unsigned n = req->max_pages - req->num_pages;
 		ssize_t ret = iov_iter_get_pages(ii,
 					&req->pages[req->num_pages],
-					n * PAGE_SIZE, &start);
+					req->max_pages - req->num_pages,
+					&start);
 		if (ret < 0)
 			return ret;
 

include/linux/uio.h

@@ -84,7 +84,7 @@ unsigned long iov_iter_alignment(const struct iov_iter *i);
 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
 			unsigned long nr_segs, size_t count);
 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
-			size_t maxsize, size_t *start);
+			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);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);

mm/iov_iter.c

@@ -310,7 +310,7 @@ void iov_iter_init(struct iov_iter *i, int direction,
 EXPORT_SYMBOL(iov_iter_init);
 
 static ssize_t get_pages_iovec(struct iov_iter *i,
-		   struct page **pages, size_t maxsize,
+		   struct page **pages, unsigned maxpages,
 		   size_t *start)
 {
 	size_t offset = i->iov_offset;
@@ -323,10 +323,10 @@ static ssize_t get_pages_iovec(struct iov_iter *i,
 	len = iov->iov_len - offset;
 	if (len > i->count)
 		len = i->count;
-	if (len > maxsize)
-		len = maxsize;
 	addr = (unsigned long)iov->iov_base + offset;
 	len += *start = addr & (PAGE_SIZE - 1);
+	if (len > maxpages * PAGE_SIZE)
+		len = maxpages * PAGE_SIZE;
 	addr &= ~(PAGE_SIZE - 1);
 	n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
 	res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
@@ -588,15 +588,14 @@ static unsigned long alignment_bvec(const struct iov_iter *i)
 }
 
 static ssize_t get_pages_bvec(struct iov_iter *i,
-		   struct page **pages, size_t maxsize,
+		   struct page **pages, unsigned maxpages,
 		   size_t *start)
 {
 	const struct bio_vec *bvec = i->bvec;
 	size_t len = bvec->bv_len - i->iov_offset;
 	if (len > i->count)
 		len = i->count;
-	if (len > maxsize)
-		len = maxsize;
+	/* can't be more than PAGE_SIZE */
 	*start = bvec->bv_offset + i->iov_offset;
 
 	get_page(*pages = bvec->bv_page);
@@ -712,13 +711,13 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
 EXPORT_SYMBOL(iov_iter_alignment);
 
 ssize_t iov_iter_get_pages(struct iov_iter *i,
-		   struct page **pages, size_t maxsize,
+		   struct page **pages, unsigned maxpages,
 		   size_t *start)
 {
 	if (i->type & ITER_BVEC)
-		return get_pages_bvec(i, pages, maxsize, start);
+		return get_pages_bvec(i, pages, maxpages, start);
 	else
-		return get_pages_iovec(i, pages, maxsize, start);
+		return get_pages_iovec(i, pages, maxpages, start);
 }
 EXPORT_SYMBOL(iov_iter_get_pages);