[PATCH] mount: support "X-" and "x-" options

Daniel Thau danthau at bedrocklinux.org
Sat Jul 3 12:21:37 UTC 2021


util-linux supports userspace application-specific capital "X-" mount
options which serve as /etc/fstab comments.  They should be ignored by
mount and should not be passed to mount(2).

util-linux also supports userspace application-specific lowercase "x-"
mount options which serve as comments both in /etc/fstab and
/run/mount/utab.  Similar to "X-", they should not be passed to
mount(2).  Had busybox support for /run/mount/utab, they should be
stored there; since busybox does not, they are simply ignored
completely.

This is commonly used by systemd, e.g. "x-systemd.device-timeout=0".
---
 util-linux/mount.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/util-linux/mount.c b/util-linux/mount.c
index 831dab9e2..e26db33ed 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -347,6 +347,8 @@ static const int32_t mount_options[] ALIGN4 = {
 		IF_DESKTOP(/* "nofail" */ MOUNT_NOFAIL,)
 		/* "_netdev" */ 0,
 		IF_DESKTOP(/* "comment=" */ 0,) /* systemd uses this in fstab */
+		IF_DESKTOP(/* "X-" */ 0,) /* fstab comment */
+		IF_DESKTOP(/* "x-" */ 0,) /* fstab and utab comment */
 	)
 
 	IF_FEATURE_MOUNT_FLAGS(
@@ -410,6 +412,8 @@ static const char mount_option_str[] ALIGN1 =
 		IF_DESKTOP("nofail\0")
 		"_netdev\0"
 		IF_DESKTOP("comment=\0") /* systemd uses this in fstab */
+		IF_DESKTOP("X-\0") /* fstab comment */
+		IF_DESKTOP("x-\0") /* fstab and utab comment */
 	)
 	IF_FEATURE_MOUNT_FLAGS(
 		// vfs flags
@@ -610,6 +614,8 @@ static unsigned long parse_mount_options(char *options, char **unrecognized)
 			 && (options[opt_len] == '\0'
 			    /* or is it "comment=" thingy in fstab? */
 			    IF_FEATURE_MOUNT_FSTAB(IF_DESKTOP( || option_str[opt_len-1] == '=' ))
+			    /* or is it a "X-" or "x-" fstab comment? */
+			    IF_FEATURE_MOUNT_FSTAB(IF_DESKTOP( || strcasecmp(option_str, "x-") == 0))
 			    )
 			) {
 				unsigned long fl = mount_options[i];
-- 
2.20.1




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