Re: [PATCH 29/31] get rid of non-advancing variants

[Al Viro <viro@zeniv.linux.org.uk>]

[braino fixed]
From 808b5178c97c4e6789ff727988c571d77b42acf7 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Jun 2022 13:05:12 -0400
Subject: [PATCH 29/31] get rid of non-advancing variants

mechanical change; will be further massaged in subsequent commits

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/uio.h | 24 ++----------------------
 lib/iov_iter.c      | 27 ++++++++++++++++++---------
 2 files changed, 20 insertions(+), 31 deletions(-)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index ab1cc218b9de..f2fc55f88e45 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -245,9 +245,9 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode
 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
 		     loff_t start, size_t count);
-ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
+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,
+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);
 void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
@@ -349,24 +349,4 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 	};
 }
 
-static inline ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
-			size_t maxsize, unsigned maxpages, size_t *start)
-{
-	ssize_t res = iov_iter_get_pages(i, pages, maxsize, maxpages, start);
-
-	if (res >= 0)
-		iov_iter_advance(i, res);
-	return res;
-}
-
-static inline ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
-			size_t maxsize, size_t *start)
-{
-	ssize_t res = iov_iter_get_pages_alloc(i, pages, maxsize, start);
-
-	if (res >= 0)
-		iov_iter_advance(i, res);
-	return res;
-}
-
 #endif
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 2ce062f1817d..d581a204c256 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1229,6 +1229,7 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 		left -= PAGE_SIZE - off;
 		if (left <= 0) {
 			buf->len += maxsize;
+			iov_iter_advance(i, maxsize);
 			return maxsize;
 		}
 		buf->len = PAGE_SIZE;
@@ -1248,7 +1249,9 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 	}
 	if (!npages)
 		return -EFAULT;
-	return maxsize - left;
+	maxsize -= left;
+	iov_iter_advance(i, maxsize);
+	return maxsize;
 }
 
 static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
@@ -1298,7 +1301,9 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
 	if (nr == 0)
 		return 0;
 
-	return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
+	maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
+	iov_iter_advance(i, maxsize);
+	return maxsize;
 }
 
 /* must be done on non-empty ITER_UBUF or ITER_IOVEC one */
@@ -1369,7 +1374,9 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
 		res = get_user_pages_fast(addr, n, gup_flags, *pages);
 		if (unlikely(res <= 0))
 			return res;
-		return min_t(size_t, maxsize, res * PAGE_SIZE - *start);
+		maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - *start);
+		iov_iter_advance(i, maxsize);
+		return maxsize;
 	}
 	if (iov_iter_is_bvec(i)) {
 		struct page **p;
@@ -1381,8 +1388,10 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
 			return n;
 		p = *pages;
 		for (int k = 0; k < n; k++)
-			get_page(*p++ = page++);
-		return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
+			get_page(p[k] = page + k);
+		maxsize = min_t(size_t, maxsize, n * PAGE_SIZE - *start);
+		iov_iter_advance(i, maxsize);
+		return maxsize;
 	}
 	if (iov_iter_is_pipe(i))
 		return pipe_get_pages(i, pages, maxsize, maxpages, start);
@@ -1392,7 +1401,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
 	return -EFAULT;
 }
 
-ssize_t iov_iter_get_pages(struct iov_iter *i,
+ssize_t iov_iter_get_pages2(struct iov_iter *i,
 		   struct page **pages, size_t maxsize, unsigned maxpages,
 		   size_t *start)
 {
@@ -1402,9 +1411,9 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 
 	return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
 }
-EXPORT_SYMBOL(iov_iter_get_pages);
+EXPORT_SYMBOL(iov_iter_get_pages2);
 
-ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize,
 		   size_t *start)
 {
@@ -1419,7 +1428,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 	}
 	return len;
 }
-EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+EXPORT_SYMBOL(iov_iter_get_pages_alloc2);
 
 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
 			       struct iov_iter *i)
-- 
2.30.2