iov_iter: Kill ITER_PIPE

The ITER_PIPE-type iterator was only used by generic_file_splice_read() and
that has been replaced and removed.  This leaves ITER_PIPE unused - so
remove it too.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-31-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: dhowells

include/linux/uio.h

@@ -11,7 +11,6 @@
 #include <uapi/linux/uio.h>
 
 struct page;
-struct pipe_inode_info;
 
 typedef unsigned int __bitwise iov_iter_extraction_t;
 
@@ -25,7 +24,6 @@ enum iter_type {
 	ITER_IOVEC,
 	ITER_KVEC,
 	ITER_BVEC,
-	ITER_PIPE,
 	ITER_XARRAY,
 	ITER_DISCARD,
 	ITER_UBUF,
@@ -74,18 +72,13 @@ struct iov_iter {
 				const struct kvec *kvec;
 				const struct bio_vec *bvec;
 				struct xarray *xarray;
-				struct pipe_inode_info *pipe;
 				void __user *ubuf;
 			};
 			size_t count;
 		};
 	};
 	union {
 		unsigned long nr_segs;
-		struct {
-			unsigned int head;
-			unsigned int start_head;
-		};
 		loff_t xarray_start;
 	};
 };
@@ -133,11 +126,6 @@ static inline bool iov_iter_is_bvec(const struct iov_iter *i)
 	return iov_iter_type(i) == ITER_BVEC;
 }
 
-static inline bool iov_iter_is_pipe(const struct iov_iter *i)
-{
-	return iov_iter_type(i) == ITER_PIPE;
-}
-
 static inline bool iov_iter_is_discard(const struct iov_iter *i)
 {
 	return iov_iter_type(i) == ITER_DISCARD;
@@ -286,8 +274,6 @@ void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec
 			unsigned long nr_segs, size_t count);
 void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
 			unsigned long nr_segs, size_t count);
-void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
-			size_t count);
 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
 void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
 		     loff_t start, size_t count);