get rid of pipe->inode

it's used only as a flag to distinguish normal pipes/FIFOs from the
internal per-task one used by file-to-file splice.  And pipe->files
would work just as well for that purpose...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/fuse/dev.c

@@ -1319,7 +1319,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
 		page_nr++;
 		ret += buf->len;
 
-		if (pipe->inode)
+		if (pipe->files)
 			do_wakeup = 1;
 	}
 

fs/pipe.c

@@ -55,7 +55,7 @@ unsigned int pipe_min_size = PAGE_SIZE;
 
 static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
 {
-	if (pipe->inode)
+	if (pipe->files)
 		mutex_lock_nested(&pipe->mutex, subclass);
 }
 
@@ -70,7 +70,7 @@ EXPORT_SYMBOL(pipe_lock);
 
 void pipe_unlock(struct pipe_inode_info *pipe)
 {
-	if (pipe->inode)
+	if (pipe->files)
 		mutex_unlock(&pipe->mutex);
 }
 EXPORT_SYMBOL(pipe_unlock);
@@ -785,7 +785,6 @@ struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
 		if (pipe->bufs) {
 			init_waitqueue_head(&pipe->wait);
 			pipe->r_counter = pipe->w_counter = 1;
-			pipe->inode = inode;
 			pipe->buffers = PIPE_DEF_BUFFERS;
 			mutex_init(&pipe->mutex);
 			return pipe;

fs/splice.c

@@ -218,7 +218,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
 			page_nr++;
 			ret += buf->len;
 
-			if (pipe->inode)
+			if (pipe->files)
 				do_wakeup = 1;
 
 			if (!--spd->nr_pages)
@@ -828,7 +828,7 @@ int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
 			ops->release(pipe, buf);
 			pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
 			pipe->nrbufs--;
-			if (pipe->inode)
+			if (pipe->files)
 				sd->need_wakeup = true;
 		}
 

include/linux/pipe_fs_i.h

@@ -41,7 +41,6 @@ struct pipe_buffer {
  *	@w_counter: writer counter
  *	@fasync_readers: reader side fasync
  *	@fasync_writers: writer side fasync
- *	@inode: inode this pipe is attached to
  *	@bufs: the circular array of pipe buffers
  **/
 struct pipe_inode_info {
@@ -57,7 +56,6 @@ struct pipe_inode_info {
 	struct page *tmp_page;
 	struct fasync_struct *fasync_readers;
 	struct fasync_struct *fasync_writers;
-	struct inode *inode;
 	struct pipe_buffer *bufs;
 };