Add the possibility for vfs.root.mountfrom tunable to accept a list of

items rather than a single one. The list is a space separated collection
of items defined as the current one accepted.

While there fix also a nit in a comment.

Obtained from:	Sandvine Incorporated
Reviewed by:	emaste
Tested by:	Giovanni Trematerra
		<giovanni dot trematerra at gmail dot com>
Sponsored by:	Sandvine Incorporated
MFC:		2 weeks

1 files changed, 15 insertions, 6 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 71084f5..962ad67 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -104,13 +104,17 @@ struct vnode	*rootvnode;
  * The root filesystem is detailed in the kernel environment variable
  * vfs.root.mountfrom, which is expected to be in the general format
  *
- * <vfsname>:[<path>]
+ * <vfsname>:[<path>][	<vfsname>:[<path>] ...]
  * vfsname   := the name of a VFS known to the kernel and capable
  *              of being mounted as root
  * path      := disk device name or other data used by the filesystem
  *              to locate its physical store
  *
- * The environment variable vfs.root.mountfrom options is a comma delimited
+ * If the environment variable vfs.root.mountfrom is a space separated list,
+ * each list element is tried in turn and the root filesystem will be mounted
+ * from the first one that suceeds.
+ *
+ * The environment variable vfs.root.mountfrom.options is a comma delimited
  * set of string mount options.  These mount options must be parseable
  * by nmount() in the kernel.
  */
@@ -1643,7 +1647,7 @@ vfs_opterror(struct vfsoptlist *opts, const char *fmt, ...)
 void
 vfs_mountroot(void)
 {
-	char *cp, *options;
+	char *cp, *cpt, *options, *tmpdev;
 	int error, i, asked = 0;
 
 	options = NULL;
@@ -1695,10 +1699,15 @@ vfs_mountroot(void)
 	 */
 	cp = getenv("vfs.root.mountfrom");
 	if (cp != NULL) {
-		error = vfs_mountroot_try(cp, options);
+		cpt = cp;
+		while ((tmpdev = strsep(&cpt, " \t")) != NULL) {
+			error = vfs_mountroot_try(tmpdev, options);
+			if (error == 0) {
+				freeenv(cp);
+				goto mounted;
+			}
+		}
 		freeenv(cp);
-		if (!error)
-			goto mounted;
 	}
 
 	/*