splice: split up __splice_from_pipe()

Split up __splice_from_pipe() into four helper functions:

  splice_from_pipe_begin()
  splice_from_pipe_next()
  splice_from_pipe_feed()
  splice_from_pipe_end()

splice_from_pipe_next() will wait (if necessary) for more buffers to
be added to the pipe.  splice_from_pipe_feed() will feed the buffers
to the supplied actor and return when there's no more data available
(or if all of the requested data has been copied).

This is necessary so that implementations can do locking around the
non-waiting splice_from_pipe_feed().

This patch should not cause any change in behavior.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/splice.h b/include/linux/splice.h
index 528dcb93c2f2..8fc2a635586e 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -36,6 +36,8 @@ struct splice_desc {
                 void *data;             /* cookie */
         } u;
         loff_t pos;                     /* file position */
+        size_t num_spliced;             /* number of bytes already spliced */
+        bool need_wakeup;               /* need to wake up writer */
 };
 
 struct partial_page {
@@ -66,6 +68,14 @@ extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
                                 splice_actor *);
 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
                                   struct splice_desc *, splice_actor *);
+extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
+                                 splice_actor *);
+extern int splice_from_pipe_next(struct pipe_inode_info *,
+                                 struct splice_desc *);
+extern void splice_from_pipe_begin(struct splice_desc *);
+extern void splice_from_pipe_end(struct pipe_inode_info *,
+                                 struct splice_desc *);
+
 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
                               struct splice_pipe_desc *);
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,