From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Fri, 4 Oct 2019 19:30:51 +0000 (-0700)
Subject: Fix automount for root filesystems
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6bd4f4545d3d334442fbe87d40ad0e0542703ce6;p=zfs

Fix automount for root filesystems

Commit 093bb64 resolved an automount failures for chroot'd processes
but inadvertently broke automounting for root filesystems where the
vfs_mntpoint is NULL.  Resolve the issue by checking for NULL in order
to generate the correct path.

Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9381
Closes #9384
---

diff --git a/module/os/linux/zfs/zfs_ctldir.c b/module/os/linux/zfs/zfs_ctldir.c
index 1e61ef06d..3b2a6eb82 100644
--- a/module/os/linux/zfs/zfs_ctldir.c
+++ b/module/os/linux/zfs/zfs_ctldir.c
@@ -1053,7 +1053,8 @@ zfsctl_snapshot_mount(struct path *path, int flags)
 	 * on mount.zfs(8).
 	 */
 	snprintf(full_path, MAXPATHLEN, "%s/.zfs/snapshot/%s",
-	    zfsvfs->z_vfs->vfs_mntpoint, dname(dentry));
+	    zfsvfs->z_vfs->vfs_mntpoint ? zfsvfs->z_vfs->vfs_mntpoint : "",
+	    dname(dentry));
 
 	/*
 	 * Multiple concurrent automounts of a snapshot are never allowed.