Merge branch 'splice-net-rewrite-splice-to-socket-fix-splice_f_more-and-handle-msg_splice_pages-in-af_tls'

David Howells says:

====================
splice, net: Rewrite splice-to-socket, fix SPLICE_F_MORE and handle MSG_SPLICE_PAGES in AF_TLS

Here are patches to do the following:

 (1) Block MSG_SENDPAGE_* flags from leaking into ->sendmsg() from
     userspace, whilst allowing splice_to_socket() to pass them in.

 (2) Allow MSG_SPLICE_PAGES to be passed into tls_*_sendmsg().  Until
     support is added, it will be ignored and a splice-driven sendmsg()
     will be treated like a normal sendmsg().  TCP, UDP, AF_UNIX and
     Chelsio-TLS already handle the flag in net-next.

 (3) Replace a chain of functions to splice-to-sendpage with a single
     function to splice via sendmsg() with MSG_SPLICE_PAGES.  This allows a
     bunch of pages to be spliced from a pipe in a single call using a
     bio_vec[] and pushes the main processing loop down into the bowels of
     the protocol driver rather than repeatedly calling in with a page at a
     time.

 (4) Provide a ->splice_eof() op[2] that allows splice to signal to its
     output that the input observed a premature EOF and that the caller
     didn't flag SPLICE_F_MORE, thereby allowing a corked socket to be
     flushed.  This attempts to maintain the current behaviour.  It is also
     not called if we didn't manage to read any data and so didn't called
     the actor function.

     This needs routing though several layers to get it down to the network
     protocol.

     [!] Note that I chose not to pass in any flags - I'm not sure it's
     	 particularly useful to pass in the splice flags; I also elected
     	 not to return any error code - though we might actually want to do
     	 that.

 (5) Provide tls_{device,sw}_splice_eof() to flush a pending TLS record if
     there is one.

 (6) Provide splice_eof() for UDP, TCP, Chelsio-TLS and AF_KCM.  AF_UNIX
     doesn't seem to pay attention to the MSG_MORE or MSG_SENDPAGE_NOTLAST
     flags.

 (7) Alter the behaviour of sendfile() and fix SPLICE_F_MORE/MSG_MORE
     signalling[1] such SPLICE_F_MORE is always signalled until we have
     read sufficient data to finish the request.  If we get a zero-length
     before we've managed to splice sufficient data, we now leave the
     socket expecting more data and leave it to userspace to deal with it.

 (8) Make AF_TLS handle the MSG_SPLICE_PAGES internal sendmsg flag.
     MSG_SPLICE_PAGES is an internal hint that tells the protocol that it
     should splice the pages supplied if it can.  Its sendpage
     implementations are then turned into wrappers around that.

Link: https://lore.kernel.org/r/499791.1685485603@warthog.procyon.org.uk/ [1]
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/ [2]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=51c78a4d532efe9543a4df019ff405f05c6157f6 # part 1
Link: https://lore.kernel.org/r/20230524153311.3625329-1-dhowells@redhat.com/ # v1
====================

Link: https://lore.kernel.org/r/20230607181920.2294972-1-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 133f0640fb24..de2cb1132f07 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);
@@ -2759,8 +2760,6 @@ extern ssize_t generic_file_splice_read(struct file *, loff_t *,
 		struct pipe_inode_info *, size_t, unsigned int);
 extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
 		struct file *, loff_t *, size_t, unsigned int);
-extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
-		struct file *out, loff_t *, size_t len, unsigned int flags);
 extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 		loff_t *opos, size_t len, unsigned int flags);
 
diff --git a/include/linux/net.h b/include/linux/net.h
index b73ad8e3c212..8defc8f1d82e 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -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);
 
diff --git a/include/linux/socket.h b/include/linux/socket.h
index bd1cc3238851..3fd3436bc09f 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -339,7 +339,9 @@ struct ucred {
 #endif
 
 /* Flags to be cleared on entry by sendmsg and sendmmsg syscalls */
-#define MSG_INTERNAL_SENDMSG_FLAGS (MSG_SPLICE_PAGES)
+#define MSG_INTERNAL_SENDMSG_FLAGS \
+	(MSG_SPLICE_PAGES | MSG_SENDPAGE_NOPOLICY | MSG_SENDPAGE_NOTLAST | \
+	 MSG_SENDPAGE_DECRYPTED)
 
 /* Setsockoptions(2) level. Thanks to BSD these must match IPPROTO_xxx */
 #define SOL_IP		0
diff --git a/include/linux/splice.h b/include/linux/splice.h
index a55179fd60fc..4fab18a6e371 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -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 */
@@ -84,6 +85,8 @@ extern long do_splice(struct file *in, loff_t *off_in,
 
 extern long do_tee(struct file *in, struct file *out, size_t len,
 		   unsigned int flags);
+extern ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,
+				loff_t *ppos, size_t len, unsigned int flags);
 
 /*
  * for dynamic pipe sizing