From a779638cf622f069a484e8802134cca3c6c71415 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Tue, 27 Sep 2016 10:45:12 +0200
Subject: [PATCH] pipe: add pipe_buf_release() helper

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/fuse/dev.c             |  7 +++----
 fs/pipe.c                 |  5 ++---
 fs/splice.c               | 17 +++++------------
 include/linux/pipe_fs_i.h | 14 ++++++++++++++
 lib/iov_iter.c            |  4 +---
 5 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index b50220c75132..d82414a1f936 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1985,10 +1985,9 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
 
 	ret = fuse_dev_do_write(fud, &cs, len);
 
-	for (idx = 0; idx < nbuf; idx++) {
-		struct pipe_buffer *buf = &bufs[idx];
-		buf->ops->release(pipe, buf);
-	}
+	for (idx = 0; idx < nbuf; idx++)
+		pipe_buf_release(pipe, &bufs[idx]);
+
 out:
 	kfree(bufs);
 	return ret;
diff --git a/fs/pipe.c b/fs/pipe.c
index 4ebe6b2e5217..67b5f1923835 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -299,8 +299,7 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
 			}
 
 			if (!buf->len) {
-				buf->ops = NULL;
-				ops->release(pipe, buf);
+				pipe_buf_release(pipe, buf);
 				curbuf = (curbuf + 1) & (pipe->buffers - 1);
 				pipe->curbuf = curbuf;
 				pipe->nrbufs = --bufs;
@@ -664,7 +663,7 @@ void free_pipe_info(struct pipe_inode_info *pipe)
 	for (i = 0; i < pipe->buffers; i++) {
 		struct pipe_buffer *buf = pipe->bufs + i;
 		if (buf->ops)
-			buf->ops->release(pipe, buf);
+			pipe_buf_release(pipe, buf);
 	}
 	if (pipe->tmp_page)
 		__free_page(pipe->tmp_page);
diff --git a/fs/splice.c b/fs/splice.c
index 188a386bf379..ae90cd1d2999 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -238,8 +238,7 @@ ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
 		pipe->nrbufs++;
 		return buf->len;
 	}
-	buf->ops->release(pipe, buf);
-	buf->ops = NULL;
+	pipe_buf_release(pipe, buf);
 	return ret;
 }
 EXPORT_SYMBOL(add_to_pipe);
@@ -516,7 +515,6 @@ static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_des
 
 	while (pipe->nrbufs) {
 		struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
-		const struct pipe_buf_operations *ops = buf->ops;
 
 		sd->len = buf->len;
 		if (sd->len > sd->total_len)
@@ -542,8 +540,7 @@ static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_des
 		sd->total_len -= ret;
 
 		if (!buf->len) {
-			buf->ops = NULL;
-			ops->release(pipe, buf);
+			pipe_buf_release(pipe, buf);
 			pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
 			pipe->nrbufs--;
 			if (pipe->files)
@@ -789,11 +786,9 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 		while (ret) {
 			struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
 			if (ret >= buf->len) {
-				const struct pipe_buf_operations *ops = buf->ops;
 				ret -= buf->len;
 				buf->len = 0;
-				buf->ops = NULL;
-				ops->release(pipe, buf);
+				pipe_buf_release(pipe, buf);
 				pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
 				pipe->nrbufs--;
 				if (pipe->files)
@@ -1032,10 +1027,8 @@ out_release:
 	for (i = 0; i < pipe->buffers; i++) {
 		struct pipe_buffer *buf = pipe->bufs + i;
 
-		if (buf->ops) {
-			buf->ops->release(pipe, buf);
-			buf->ops = NULL;
-		}
+		if (buf->ops)
+			pipe_buf_release(pipe, buf);
 	}
 
 	if (!bytes)
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 10876f3cb3da..d24fa6da6ae3 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -126,6 +126,20 @@ static inline void pipe_buf_get(struct pipe_inode_info *pipe,
 	buf->ops->get(pipe, buf);
 }
 
+/**
+ * pipe_buf_release - put a reference to a pipe_buffer
+ * @pipe:	the pipe that the buffer belongs to
+ * @buf:	the buffer to put a reference to
+ */
+static inline void pipe_buf_release(struct pipe_inode_info *pipe,
+				    struct pipe_buffer *buf)
+{
+	const struct pipe_buf_operations *ops = buf->ops;
+
+	buf->ops = NULL;
+	ops->release(pipe, buf);
+}
+
 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
 #define PIPE_SIZE		PAGE_SIZE
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 659eaafcde65..48b8c27acabb 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -709,9 +709,7 @@ static void pipe_advance(struct iov_iter *i, size_t size)
 		int unused = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
 		/* [curbuf,unused) is in use.  Free [idx,unused) */
 		while (idx != unused) {
-			buf = &pipe->bufs[idx];
-			buf->ops->release(pipe, buf);
-			buf->ops = NULL;
+			pipe_buf_release(pipe, &pipe->bufs[idx]);
 			idx = next_idx(idx, pipe);
 			pipe->nrbufs--;
 		}