linux-kernel - [RFC -next 08/10] fs: Add sendfile flags for sendfile2

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Message-ID: <20250319001521.53249-9-jdamato@fastly.com>
Date: Wed, 19 Mar 2025 00:15:19 +0000
From: Joe Damato <jdamato@...tly.com>
To: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	asml.silence@...il.com,
	linux-fsdevel@...r.kernel.org,
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	Joe Damato <jdamato@...tly.com>
Subject: [RFC -next 08/10] fs: Add sendfile flags for sendfile2

Add a default flag (SENDFILE_DEFAULT) and a flag for requesting zerocopy
notifications (SENDFILE_ZC). do_sendfile is updated to pass through the
corresponding splice flag to enable zerocopy notifications.

Signed-off-by: Joe Damato <jdamato@...tly.com>
---
 fs/read_write.c          |  5 +++++
 include/linux/sendfile.h | 10 ++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 include/linux/sendfile.h

diff --git a/fs/read_write.c b/fs/read_write.c
index 057e5f37645d..e3929fd0f605 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/syscalls.h>
 #include <linux/pagemap.h>
+#include <linux/sendfile.h>
 #include <linux/splice.h>
 #include <linux/compat.h>
 #include <linux/mount.h>
@@ -1360,6 +1361,10 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 		retval = rw_verify_area(WRITE, fd_file(out), &out_pos, count);
 		if (retval < 0)
 			return retval;
+
+		if (flags & SENDFILE_ZC)
+			fl |= SPLICE_F_ZC;
+
 		retval = do_splice_direct(fd_file(in), &pos, fd_file(out), &out_pos,
 					  count, fl);
 	} else {
diff --git a/include/linux/sendfile.h b/include/linux/sendfile.h
new file mode 100644
index 000000000000..0bd3c76ea6f2
--- /dev/null
+++ b/include/linux/sendfile.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SENDFILE_H
+#define SENDFILE_H
+
+#define SENDFILE_DEFAULT (0x1)  /* normal sendfile */
+#define SENDFILE_ZC (0x2)       /* sendfile which generates ZC notifications */
+
+#define SENDFILE_ALL (SENDFILE_DEFAULT|SENDFILE_ZC)
+
+#endif
-- 
2.43.0