diff mbox series

[38/44] iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()

Message ID 20220622041552.737754-38-viro@zeniv.linux.org.uk (mailing list archive)
State New, archived
Headers show
Series [01/44] 9p: handling Rerror without copy_from_iter_full() | expand

Commit Message

Al Viro June 22, 2022, 4:15 a.m. UTC
... and untangle the cleanup on failure to add into pipe.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/splice.c | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

Comments

Jeff Layton June 28, 2022, 12:18 p.m. UTC | #1
On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote:
> ... and untangle the cleanup on failure to add into pipe.
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  fs/splice.c | 47 ++++++++++++++++++++++++-----------------------
>  1 file changed, 24 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 6645b30ec990..9f84bd21f64c 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1160,39 +1160,40 @@ static int iter_to_pipe(struct iov_iter *from,
>  	};
>  	size_t total = 0;
>  	int ret = 0;
> -	bool failed = false;
>  
> -	while (iov_iter_count(from) && !failed) {
> +	while (iov_iter_count(from)) {
>  		struct page *pages[16];
> -		ssize_t copied;
> +		ssize_t left;
>  		size_t start;
> -		int n;
> +		int i, n;
>  
> -		copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
> -		if (copied <= 0) {
> -			ret = copied;
> +		left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start);
> +		if (left <= 0) {
> +			ret = left;
>  			break;
>  		}
>  
> -		for (n = 0; copied; n++, start = 0) {
> -			int size = min_t(int, copied, PAGE_SIZE - start);
> -			if (!failed) {
> -				buf.page = pages[n];
> -				buf.offset = start;
> -				buf.len = size;
> -				ret = add_to_pipe(pipe, &buf);
> -				if (unlikely(ret < 0)) {
> -					failed = true;
> -				} else {
> -					iov_iter_advance(from, ret);
> -					total += ret;
> -				}
> -			} else {
> -				put_page(pages[n]);
> +		n = DIV_ROUND_UP(left + start, PAGE_SIZE);
> +		for (i = 0; i < n; i++) {
> +			int size = min_t(int, left, PAGE_SIZE - start);
> +
> +			buf.page = pages[i];
> +			buf.offset = start;
> +			buf.len = size;
> +			ret = add_to_pipe(pipe, &buf);
> +			if (unlikely(ret < 0)) {
> +				iov_iter_revert(from, left);
> +				// this one got dropped by add_to_pipe()
> +				while (++i < n)
> +					put_page(pages[i]);
> +				goto out;
>  			}
> -			copied -= size;
> +			total += ret;
> +			left -= size;
> +			start = 0;
>  		}
>  	}
> +out:
>  	return total ? total : ret;
>  }
>  

Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff mbox series

Patch

diff --git a/fs/splice.c b/fs/splice.c
index 6645b30ec990..9f84bd21f64c 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1160,39 +1160,40 @@  static int iter_to_pipe(struct iov_iter *from,
 	};
 	size_t total = 0;
 	int ret = 0;
-	bool failed = false;
 
-	while (iov_iter_count(from) && !failed) {
+	while (iov_iter_count(from)) {
 		struct page *pages[16];
-		ssize_t copied;
+		ssize_t left;
 		size_t start;
-		int n;
+		int i, n;
 
-		copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start);
-		if (copied <= 0) {
-			ret = copied;
+		left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start);
+		if (left <= 0) {
+			ret = left;
 			break;
 		}
 
-		for (n = 0; copied; n++, start = 0) {
-			int size = min_t(int, copied, PAGE_SIZE - start);
-			if (!failed) {
-				buf.page = pages[n];
-				buf.offset = start;
-				buf.len = size;
-				ret = add_to_pipe(pipe, &buf);
-				if (unlikely(ret < 0)) {
-					failed = true;
-				} else {
-					iov_iter_advance(from, ret);
-					total += ret;
-				}
-			} else {
-				put_page(pages[n]);
+		n = DIV_ROUND_UP(left + start, PAGE_SIZE);
+		for (i = 0; i < n; i++) {
+			int size = min_t(int, left, PAGE_SIZE - start);
+
+			buf.page = pages[i];
+			buf.offset = start;
+			buf.len = size;
+			ret = add_to_pipe(pipe, &buf);
+			if (unlikely(ret < 0)) {
+				iov_iter_revert(from, left);
+				// this one got dropped by add_to_pipe()
+				while (++i < n)
+					put_page(pages[i]);
+				goto out;
 			}
-			copied -= size;
+			total += ret;
+			left -= size;
+			start = 0;
 		}
 	}
+out:
 	return total ? total : ret;
 }