[PATCH] splice: add direct fd <-> fd splicing support

It's more efficient for sendfile() emulation. Basically we cache an
internal private pipe and just use that as the intermediate area for
pages. Direct splicing is not available from sys_splice(), it is only
meant to be used for sendfile() emulation.

Additional patch from Ingo Molnar to avoid the PIPE_BUFFERS loop at
exit for the normal fast path.

Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 541f4828f5e7..e194ec75833d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -684,6 +684,7 @@ static inline void prefetch_stack(struct task_struct *t) { }
 
 struct audit_context;           /* See audit.c */
 struct mempolicy;
+struct pipe_inode_info;
 
 enum sleep_type {
         SLEEP_NORMAL,
@@ -882,6 +883,11 @@ struct task_struct {
 
         atomic_t fs_excl;       /* holding fs exclusive resources */
         struct rcu_head rcu;
+
+        /*
+         * cache last used pipe for splice
+         */
+        struct pipe_inode_info *splice_pipe;
 };
 
 static inline pid_t process_group(struct task_struct *tsk)