In vfs_nmount(), check to see if "update" mount option was passed

in, and if so, set MNT_UPDATE filesystem flag.
vfs_nmount() calls vfs_domount(), and there is special logic
inside vfs_domount() if MNT_UPDATE is set.  This is very important
when we want to do an update mount of the root filesystem, using nmount().

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index a4260f3..2c02257 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -516,6 +516,15 @@ vfs_donmount(struct thread *td, int fsflags, struct uio *fsoptions)
 	}
 
 	/*
+	 * We need to see if we have the "update" option
+	 * before we call vfs_domount(), since vfs_domount() has special
+	 * logic based on MNT_UPDATE.  This is very important
+	 * when we want to update the root filesystem.
+	 */ 
+	if (vfs_getopt(optlist, "update", NULL, NULL) == 0)
+		fsflags |= MNT_UPDATE;
+
+	/*
 	 * Be ultra-paranoid about making sure the type and fspath
 	 * variables will fit in our mp buffers, including the
 	 * terminating NUL.