Improve the warnings for dump -L and do not bother doing the snapshot if

it is specified for read-only filesystems.

Submitted by:   Jason Young <jyoung8607@hotmail.com>
PR:     46672

2 files changed, 11 insertions, 3 deletions

diff --git a/sbin/dump/dump.8 b/sbin/dump/dump.8
index 2abb594..0e86ebe 100644
--- a/sbin/dump/dump.8
+++ b/sbin/dump/dump.8
@@ -211,6 +211,7 @@ takes a snapshot of the file system in the
 directory in the root of the filesystem being dumped and
 then does a dump of the snapshot.
 The snapshot is removed when the dump is complete.
+This option is ignored for unmounted or read-only filesystems.
 If the
 .Pa .snap
 directory does not exist in the root of the filesystem being dumped,
diff --git a/sbin/dump/main.c b/sbin/dump/main.c
index c6beb2a..baf8a25 100644
--- a/sbin/dump/main.c
+++ b/sbin/dump/main.c
@@ -309,9 +309,16 @@ main(int argc, char *argv[])
 	spcl.c_filesys[NAMELEN-1]='\0';
 
 	if ((mntpt = getmntpt(disk, &mntflags)) != 0) {
-		if (snapdump == 0) {
-			msg("WARNING: %s\n",
-			    "should use -L when dumping live filesystems!");
+		if (mntflags & MNT_RDONLY) {
+			if (snapdump != 0) {
+				msg("WARNING: %s\n",
+				    "-L ignored for read-only filesystem.");
+				snapdump = 0;
+			}
+		} else if (snapdump == 0) {
+			msg("WARNING: %s%s\n",
+			    "should use -L when dumping live read-write ",
+			    "filesystems!");
 		} else {
 			char snapname[BUFSIZ], snapcmd[BUFSIZ];