svn commit: r342135 - head/sys/kern

[Kirk McKusick]

Author: mckusick
Date: Sat Dec 15 19:04:50 2018
New Revision: 342135
URL: https://svnweb.freebsd.org/changeset/base/342135

Log:
  Under UFS/FFS the VFS_ROOT() function will return an error if the inode
  check-hash fails. Panic'ing is not an appropriate response. So, check
  for an error return from VFS_ROOT() and when an error is reported,
  unwind and return the error.
  
  Reported by:  Gary Jennejohn (gj)
  Sponsored by: Netflix

Modified:
  head/sys/kern/vfs_mount.c

Modified: head/sys/kern/vfs_mount.c
==============================================================================
--- head/sys/kern/vfs_mount.c	Sat Dec 15 18:49:30 2018	(r342134)
+++ head/sys/kern/vfs_mount.c	Sat Dec 15 19:04:50 2018	(r342135)
@@ -841,7 +841,7 @@ vfs_domount_first(
 	struct vattr va;
 	struct mount *mp;
 	struct vnode *newdp;
-	int error;
+	int error, error1;
 
 	ASSERT_VOP_ELOCKED(vp, __func__);
 	KASSERT((fsflags & MNT_UPDATE) == 0, ("MNT_UPDATE shouldn't be here"));
@@ -893,8 +893,14 @@ vfs_domount_first(
 	 * XXX The final recipients of VFS_MOUNT just overwrite the ndp they
 	 * get.  No freeing of cn_pnbuf.
 	 */
-	error = VFS_MOUNT(mp);
-	if (error != 0) {
+	error1 = 0;
+	if ((error = VFS_MOUNT(mp)) != 0 ||
+	    (error1 = VFS_ROOT(mp, LK_EXCLUSIVE, &newdp)) != 0) {
+		if (error1 != 0) {
+			error = error1;
+			if ((error1 = VFS_UNMOUNT(mp, 0)) != 0)
+				printf("VFS_UNMOUNT returned %d\n", error1);
+		}
 		vfs_unbusy(mp);
 		mp->mnt_vnodecovered = NULL;
 		vfs_mount_destroy(mp);
@@ -904,6 +910,7 @@ vfs_domount_first(
 		vrele(vp);
 		return (error);
 	}
+	VOP_UNLOCK(newdp, 0);
 
 	if (mp->mnt_opt != NULL)
 		vfs_freeopts(mp->mnt_opt);
@@ -935,8 +942,7 @@ vfs_domount_first(
 	TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
 	mtx_unlock(&mountlist_mtx);
 	vfs_event_signal(NULL, VQ_MOUNT, 0);
-	if (VFS_ROOT(mp, LK_EXCLUSIVE, &newdp))
-		panic("mount: lost mount");
+	vn_lock(newdp, LK_EXCLUSIVE | LK_RETRY);
 	VOP_UNLOCK(vp, 0);
 	EVENTHANDLER_DIRECT_INVOKE(vfs_mounted, mp, newdp, td);
 	VOP_UNLOCK(newdp, 0);