[PATCH 21/29] iov_iter: Split iov_iter_get_pages()

[David Howells <dhowells@xxxxxxxxxx>]

Split iov_iter_get_pages() by type.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 lib/iov_iter.c |   46 +++++++++++++++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5744ddec854f..a2de201b947f 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1611,6 +1611,8 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 	unsigned int iter_head, npages;
 	size_t capacity;
 
+	if (maxsize > i->count)
+		maxsize = i->count;
 	if (!maxsize)
 		return 0;
 
@@ -1625,19 +1627,14 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 	return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
 }
 
-static ssize_t xxx_get_pages(struct iov_iter *i,
+static ssize_t iovec_get_pages(struct iov_iter *i,
 		   struct page **pages, size_t maxsize, unsigned maxpages,
 		   size_t *start)
 {
 	if (maxsize > i->count)
 		maxsize = i->count;
 
-	if (unlikely(iov_iter_is_pipe(i)))
-		return pipe_get_pages(i, pages, maxsize, maxpages, start);
-	if (unlikely(iov_iter_is_discard(i)))
-		return -EFAULT;
-
-	iterate_all_kinds(i, maxsize, v, ({
+	iterate_over_iovec(i, maxsize, v, ({
 		unsigned long addr = (unsigned long)v.iov_base;
 		size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
 		int n;
@@ -1653,18 +1650,33 @@ static ssize_t xxx_get_pages(struct iov_iter *i,
 		if (unlikely(res < 0))
 			return res;
 		return (res == n ? len : res * PAGE_SIZE) - *start;
-	0;}),({
+	0;}));
+	return 0;
+}
+
+static ssize_t bvec_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize, unsigned maxpages,
+		   size_t *start)
+{
+	if (maxsize > i->count)
+		maxsize = i->count;
+
+	iterate_over_bvec(i, maxsize, v, ({
 		/* can't be more than PAGE_SIZE */
 		*start = v.bv_offset;
 		get_page(*pages = v.bv_page);
 		return v.bv_len;
-	}),({
-		return -EFAULT;
-	})
-	)
+	}));
 	return 0;
 }
 
+static ssize_t no_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize, unsigned maxpages,
+		   size_t *start)
+{
+	return -EFAULT;
+}
+
 static struct page **get_pages_array(size_t n)
 {
 	return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
@@ -2179,7 +2191,7 @@ static const struct iov_iter_ops iovec_iter_ops = {
 	.zero				= iovec_zero,
 	.alignment			= iovec_alignment,
 	.gap_alignment			= iovec_gap_alignment,
-	.get_pages			= xxx_get_pages,
+	.get_pages			= iovec_get_pages,
 	.get_pages_alloc		= xxx_get_pages_alloc,
 	.npages				= xxx_npages,
 	.dup_iter			= xxx_dup_iter,
@@ -2213,7 +2225,7 @@ static const struct iov_iter_ops kvec_iter_ops = {
 	.zero				= kvec_zero,
 	.alignment			= kvec_alignment,
 	.gap_alignment			= kvec_gap_alignment,
-	.get_pages			= xxx_get_pages,
+	.get_pages			= no_get_pages,
 	.get_pages_alloc		= xxx_get_pages_alloc,
 	.npages				= xxx_npages,
 	.dup_iter			= xxx_dup_iter,
@@ -2247,7 +2259,7 @@ static const struct iov_iter_ops bvec_iter_ops = {
 	.zero				= bvec_zero,
 	.alignment			= bvec_alignment,
 	.gap_alignment			= bvec_gap_alignment,
-	.get_pages			= xxx_get_pages,
+	.get_pages			= bvec_get_pages,
 	.get_pages_alloc		= xxx_get_pages_alloc,
 	.npages				= xxx_npages,
 	.dup_iter			= xxx_dup_iter,
@@ -2281,7 +2293,7 @@ static const struct iov_iter_ops pipe_iter_ops = {
 	.zero				= pipe_zero,
 	.alignment			= pipe_alignment,
 	.gap_alignment			= no_gap_alignment,
-	.get_pages			= xxx_get_pages,
+	.get_pages			= pipe_get_pages,
 	.get_pages_alloc		= xxx_get_pages_alloc,
 	.npages				= xxx_npages,
 	.dup_iter			= xxx_dup_iter,
@@ -2315,7 +2327,7 @@ static const struct iov_iter_ops discard_iter_ops = {
 	.zero				= discard_zero,
 	.alignment			= no_alignment,
 	.gap_alignment			= no_gap_alignment,
-	.get_pages			= xxx_get_pages,
+	.get_pages			= no_get_pages,
 	.get_pages_alloc		= xxx_get_pages_alloc,
 	.npages				= xxx_npages,
 	.dup_iter			= xxx_dup_iter,