From 38492c5743f8b7213ca86f0cd72ea625af35d5ef Mon Sep 17 00:00:00 2001
From: Dmitry Safonov <dima@arista.com>
Date: Tue, 7 Oct 2025 04:46:47 +0100
Subject: [PATCH] gen_init_cpio: Ignore fsync() returning EINVAL on pipes

The reproducer:
echo | ./usr/gen_init_cpio /dev/stdin > /dev/null

fsync() on a pipe fd returns -EINVAL, which makes gen_init_cpio fail.
Ignore -EINVAL from fsync().

Fixes: ae18b94099b0 ("gen_init_cpio: support -o <output_file> parameter")
Cc: David Disseldorp <ddiss@suse.de>
Cc: Nicolas Schier <nsc@kernel.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
Link: https://patch.msgid.link/20251007-gen_init_cpio-pipe-v2-1-b098ab94b58a@arista.com
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 usr/gen_init_cpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c
index 75e9561ba313..b7296edc6626 100644
--- a/usr/gen_init_cpio.c
+++ b/usr/gen_init_cpio.c
@@ -112,7 +112,10 @@ static int cpio_trailer(void)
 	    push_pad(padlen(offset, 512)) < 0)
 		return -1;
 
-	return fsync(outfd);
+	if (fsync(outfd) < 0 && errno != EINVAL)
+		return -1;
+
+	return 0;
 }
 
 static int cpio_mkslink(const char *name, const char *target,
-- 
2.47.3