svn commit: r344155 - stable/11/sys/fs/nullfs

[Konstantin Belousov]

Author: kib
Date: Fri Feb 15 11:27:21 2019
New Revision: 344155
URL: https://svnweb.freebsd.org/changeset/base/344155

Log:
  MFC r343897, r343898:
  Some style for nullfs_mount().
  Before using VTONULL(), check that the covered vnode belongs to nullfs.

Modified:
  stable/11/sys/fs/nullfs/null_vfsops.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/fs/nullfs/null_vfsops.c
==============================================================================
--- stable/11/sys/fs/nullfs/null_vfsops.c       Fri Feb 15 11:20:25 2019        
(r344154)
+++ stable/11/sys/fs/nullfs/null_vfsops.c       Fri Feb 15 11:27:21 2019        
(r344155)
@@ -72,14 +72,15 @@ static vfs_extattrctl_t     nullfs_extattrctl;
 static int
 nullfs_mount(struct mount *mp)
 {
-       int error = 0;
        struct vnode *lowerrootvp, *vp;
        struct vnode *nullm_rootvp;
        struct null_mount *xmp;
        struct thread *td = curthread;
+       struct null_node *nn;
+       struct nameidata nd, *ndp;
        char *target;
-       int isvnunlocked = 0, len;
-       struct nameidata nd, *ndp = &nd;
+       int error, len;
+       bool isvnunlocked;
 
        NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
 
@@ -111,14 +112,18 @@ nullfs_mount(struct mount *mp)
        /*
         * Unlock lower node to avoid possible deadlock.
         */
-       if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
+       if (mp->mnt_vnodecovered->v_op == &null_vnodeops &&
            VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
                VOP_UNLOCK(mp->mnt_vnodecovered, 0);
-               isvnunlocked = 1;
+               isvnunlocked = true;
+       } else {
+               isvnunlocked = false;
        }
+
        /*
         * Find lower node
         */
+       ndp = &nd;
        NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
        error = namei(ndp);
 
@@ -141,10 +146,13 @@ nullfs_mount(struct mount *mp)
        /*
         * Check multi null mount to avoid `lock against myself' panic.
         */
-       if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
-               NULLFSDEBUG("nullfs_mount: multi null mount?\n");
-               vput(lowerrootvp);
-               return (EDEADLK);
+       if (mp->mnt_vnodecovered->v_op == &null_vnodeops) {
+               nn = VTONULL(mp->mnt_vnodecovered);
+               if (nn == NULL || lowerrootvp == nn->null_lowervp) {
+                       NULLFSDEBUG("nullfs_mount: multi null mount?\n");
+                       vput(lowerrootvp);
+                       return (EDEADLK);
+               }
        }
 
        xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
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