diff mbox series

[RFC,-next,04/10] splice: Add SPLICE_F_ZC and attach ubuf

Message ID 20250319001521.53249-5-jdamato@fastly.com (mailing list archive)
State RFC
Headers show
Series Add ZC notifications to splice and sendfile | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success Errors and warnings before: 26 (+0) this patch: 26 (+0)
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 23 this patch: 23
netdev/checkpatch warning CHECK: spaces preferred around that '|' (ctx:VxV) WARNING: line length of 94 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 11 this patch: 11
netdev/source_inline success Was 0 now: 0

Commit Message

Joe Damato March 19, 2025, 12:15 a.m. UTC 
Add the SPLICE_F_ZC flag and when it is set, allocate a ubuf and attach
it to generate zerocopy notifications.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 fs/splice.c            | 20 ++++++++++++++++++++
 include/linux/splice.h |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/splice.c b/fs/splice.c
index 1f27ce6d1c34..6dc60f47f84e 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -875,6 +875,11 @@  static ssize_t splice_socket_generic(struct pipe_inode_info *pipe,
 		if (out->f_flags & O_NONBLOCK)
 			msg.msg_flags |= MSG_DONTWAIT;
 
+		if (unlikely(flags & SPLICE_F_ZC) && ubuf_info) {
+			msg.msg_flags = MSG_ZEROCOPY;
+			msg.msg_ubuf = ubuf_info;
+		}
+
 		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, bvec, bc,
 			      len - remain);
 		ret = sock_sendmsg(sock, &msg);
@@ -1223,12 +1228,27 @@  static ssize_t do_splice_direct_actor(struct file *in, loff_t *ppos,
 	if (unlikely(out->f_flags & O_APPEND))
 		return -EINVAL;
 
+	if (unlikely(flags & SPLICE_F_ZC)) {
+		struct socket *sock = sock_from_file(out);
+		struct sock *sk = sock->sk;
+		struct ubuf_info *ubuf_info;
+
+		ubuf_info = msg_zerocopy_realloc(sk, len, NULL);
+		if (!ubuf_info)
+			return -ENOMEM;
+		sd.ubuf_info = ubuf_info;
+	}
+
 	ret = splice_direct_to_actor(in, &sd, actor);
 	if (ret > 0)
 		*ppos = sd.pos;
 
+	if (unlikely(flags & SPLICE_F_ZC))
+		refcount_dec(&sd.ubuf_info->refcnt);
+
 	return ret;
 }
+
 /**
  * do_splice_direct - splices data directly between two files
  * @in:		file to splice from
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 7477df3916e2..a88588cf2754 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -21,8 +21,9 @@ 
 				 /* from/to, of course */
 #define SPLICE_F_MORE	(0x04)	/* expect more data */
 #define SPLICE_F_GIFT	(0x08)	/* pages passed in are a gift */
+#define SPLICE_F_ZC	(0x10)  /* generate zero copy notifications */
 
-#define SPLICE_F_ALL (SPLICE_F_MOVE|SPLICE_F_NONBLOCK|SPLICE_F_MORE|SPLICE_F_GIFT)
+#define SPLICE_F_ALL (SPLICE_F_MOVE|SPLICE_F_NONBLOCK|SPLICE_F_MORE|SPLICE_F_GIFT|SPLICE_F_ZC)
 
 /*
  * Passed to the actors