In the !MNT_BYFSID case, return EINVAL from unmount(2) when the

specified directory is not found in the mount list. Before the
MNT_BYFSID changes, unmount(2) used to return ENOENT for a nonexistent
path and EINVAL for a non-mountpoint, but we can no longer distinguish
between these cases. Of the two error codes, EINVAL was more likely
to occur in practice, and it was the only one of the two that was
documented.

Update the manual page to match the current behaviour.

Suggested by:	tjr
Reviewed by:	tjr

1 files changed, 9 insertions, 2 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index 7d166f02f45d..efc78745bbbf 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1255,8 +1255,15 @@ unmount(td, uap)
 		mtx_unlock(&mountlist_mtx);
 	}
 	free(pathbuf, M_TEMP);
-	if (mp == NULL)
-		return (ENOENT);
+	if (mp == NULL) {
+		/*
+		 * Previously we returned ENOENT for a nonexistent path and
+		 * EINVAL for a non-mountpoint.  We cannot tell these apart
+		 * now, so in the !MNT_BYFSID case return the more likely
+		 * EINVAL for compatibility.
+		 */
+		return ((uap->flags & MNT_BYFSID) ? ENOENT : EINVAL);
+	}
 
 	/*
 	 * Only root, or the user that did the original mount is