Kernels since version 6.8 have an option CONFIG_BLK_DEV_WRITE_MOUNTED
that, if disabled, prevents accidental writes to and data corruption of
mounted devices.

This breaks online resizing with resize2fs, as it opens the device with
O_RDWR. However, it appears that this is not necessary and by changing
it to O_RDONLY, online resizing works again.

See also: https://unix.stackexchange.com/a/796881

Signed-off-by: Hanno Böck <hanno@hboeck.de>
--- a/resize/main.c	2026-03-06 18:17:36.000000000 +0100
+++ b/resize/main.c	2026-06-13 10:53:46.165030199 +0200
@@ -256,7 +256,7 @@ int main (int argc, char ** argv)
 	int		force_min_size = 0;
 	int		print_min_size = 0;
 	int		fd, ret;
-	int		open_flags = O_RDWR;
+	int		open_flags = O_RDONLY;
 	blk64_t		new_size = 0;
 	blk64_t		max_size = 0;
 	blk64_t		min_size = 0;
@@ -364,9 +364,6 @@ int main (int argc, char ** argv)
 		len = 2 * len;
 	}
 
-	if (print_min_size)
-		open_flags = O_RDONLY;
-
 	fd = ext2fs_open_file(device_name, open_flags, 0);
 	if (fd < 0) {
 		com_err("open", errno, _("while opening %s"),