overlayfs_mount: create delta dir if it doesn't exist

(This *should* fix the lxc-test-snapshot testcase, but doesn't seem to by itself.) If it doesn't exist, we may as well start with an empty one. This is needed when creating an overlayfs snapshot. Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Stéphane Graber <stgraber@ubuntu.com>

overlayfs_mount: create delta dir if it doesn't exist
e228426c · Serge Hallyn · Stéphane Graber · 1212197e · e228426c
Commit e228426c authored Sep 21, 2015 by Serge Hallyn Committed by Stéphane Graber Sep 21, 2015
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bdev.c src/lxc/bdev.c +4 -0

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--- a/src/lxc/bdev.c
+++ b/src/lxc/bdev.c
@@ -2224,6 +2224,10 @@ static int overlayfs_mount(struct bdev *bdev)
 	*upper = '\0';
 	upper++;

+	// if delta doesn't yet exist, create it
+	if (mkdir_p(upper, 0755) < 0 && errno != EEXIST)
+		return -22;
+
 	// overlayfs.v22 or higher needs workdir option
 	// if upper is /var/lib/lxc/c2/delta0,
 	// then workdir is /var/lib/lxc/c2/olwork