Commit 2bfc6685 authored by David Howells's avatar David Howells Committed by Jakub Kicinski
Browse files

splice, net: Add a splice_eof op to file-ops and socket-ops 



Add an optional method, ->splice_eof(), to allow splice to indicate the
premature termination of a splice to struct file_operations and struct
proto_ops.

This is called if sendfile() or splice() encounters all of the following
conditions inside splice_direct_to_actor():

 (1) the user did not set SPLICE_F_MORE (splice only), and

 (2) an EOF condition occurred (->splice_read() returned 0), and

 (3) we haven't read enough to fulfill the request (ie. len > 0 still), and

 (4) we have already spliced at least one byte.

A further patch will modify the behaviour of SPLICE_F_MORE to always be
passed to the actor if either the user set it or we haven't yet read
sufficient data to fulfill the request.

Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/


Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJakub Kicinski <kuba@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Matthew Wilcox <willy@infradead.org>
cc: Jan Kara <jack@suse.cz>
cc: Jeff Layton <jlayton@kernel.org>
cc: David Hildenbrand <david@redhat.com>
cc: Christian Brauner <brauner@kernel.org>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Boris Pismenny <borisp@nvidia.com>
cc: John Fastabend <john.fastabend@gmail.com>
cc: linux-mm@kvack.org
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 2dc334f1

fs/splice.c

+30 −1
Original line number Diff line number Diff line
@@ -969,6 +969,17 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, 
	return out->f_op->splice_write(pipe, out, ppos, len, flags);

}



/*

 * Indicate to the caller that there was a premature EOF when reading from the

 * source and the caller didn't indicate they would be sending more data after

 * this.

 */

static void do_splice_eof(struct splice_desc *sd)

{

	if (sd->splice_eof)

		sd->splice_eof(sd);

}



/*

 * Attempt to initiate a splice from a file to a pipe.

 */
@@ -1068,7 +1079,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, 


		ret = do_splice_to(in, &pos, pipe, len, flags);

		if (unlikely(ret <= 0))

			goto out_release;

			goto read_failure;



		read_len = ret;

		sd->total_len = read_len;
@@ -1108,6 +1119,15 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, 
	file_accessed(in);

	return bytes;



read_failure:

	/*

	 * If the user did *not* set SPLICE_F_MORE *and* we didn't hit that

	 * "use all of len" case that cleared SPLICE_F_MORE, *and* we did a

	 * "->splice_in()" that returned EOF (ie zero) *and* we have sent at

	 * least 1 byte *then* we will also do the ->splice_eof() call.

	 */

	if (ret == 0 && !more && len > 0 && bytes)

		do_splice_eof(sd);

out_release:

	/*

	 * If we did an incomplete transfer we must release
@@ -1136,6 +1156,14 @@ static int direct_splice_actor(struct pipe_inode_info *pipe, 
			      sd->flags);

}



static void direct_file_splice_eof(struct splice_desc *sd)

{

	struct file *file = sd->u.file;



	if (file->f_op->splice_eof)

		file->f_op->splice_eof(file);

}



/**

 * do_splice_direct - splices data directly between two files

 * @in:		file to splice from
@@ -1161,6 +1189,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, 
		.flags		= flags,

		.pos		= *ppos,

		.u.file		= out,

		.splice_eof	= direct_file_splice_eof,

		.opos		= opos,

	};

	long ret;

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -1796,6 +1796,7 @@ struct file_operations { 
	int (*flock) (struct file *, int, struct file_lock *);

	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);

	ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);

	void (*splice_eof)(struct file *file);

	int (*setlease)(struct file *, long, struct file_lock **, void **);

	long (*fallocate)(struct file *file, int mode, loff_t offset,

			  loff_t len);

include/linux/net.h

+1 −0
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ struct proto_ops { 
				      int offset, size_t size, int flags);

	ssize_t 	(*splice_read)(struct socket *sock,  loff_t *ppos,

				       struct pipe_inode_info *pipe, size_t len, unsigned int flags);

	void		(*splice_eof)(struct socket *sock);

	int		(*set_peek_off)(struct sock *sk, int val);

	int		(*peek_len)(struct socket *sock);

include/linux/splice.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct splice_desc { 
		struct file *file;	/* file to read/write */

		void *data;		/* cookie */

	} u;

	void (*splice_eof)(struct splice_desc *sd); /* Unexpected EOF handler */

	loff_t pos;			/* file position */

	loff_t *opos;			/* sendfile: output position */

	size_t num_spliced;		/* number of bytes already spliced */

include/net/sock.h

+1 −0
Original line number Diff line number Diff line
@@ -1279,6 +1279,7 @@ struct proto { 
					   size_t len, int flags, int *addr_len);

	int			(*sendpage)(struct sock *sk, struct page *page,

					int offset, size_t size, int flags);

	void			(*splice_eof)(struct socket *sock);

	int			(*bind)(struct sock *sk,

					struct sockaddr *addr, int addr_len);

	int			(*bind_add)(struct sock *sk,