Keep trying to flush the vnode list for the mount while some are still

busy and we are making progress towards making them not busy. This is
needed because smbfs vnodes reference their parent directory but may
appear after their parent in the mount's vnode list; one pass over the
list is not sufficient in this case.

This stops attempts to unmount idle smbfs mounts failing with EBUSY.

3 files changed, 19 insertions, 2 deletions

diff --git a/sys/fs/smbfs/smbfs.h b/sys/fs/smbfs/smbfs.h
index b6f97bec7047..50487916826f 100644
--- a/sys/fs/smbfs/smbfs.h
+++ b/sys/fs/smbfs/smbfs.h
@@ -89,6 +89,7 @@ struct smbmount {
 	struct lock		sm_hashlock;
 	LIST_HEAD(smbnode_hashhead, smbnode) *sm_hash;
 	u_long			sm_hashlen;
+	int			sm_didrele;
 };
 
 #define VFSTOSMBFS(mp)		((struct smbmount *)((mp)->mnt_data))
diff --git a/sys/fs/smbfs/smbfs_node.c b/sys/fs/smbfs/smbfs_node.c
index 7f17967d43fe..0feadd0eec12 100644
--- a/sys/fs/smbfs/smbfs_node.c
+++ b/sys/fs/smbfs/smbfs_node.c
@@ -322,6 +322,11 @@ smbfs_reclaim(ap)
 		if (dvp->v_usecount >= 1) {
 			VI_UNLOCK(dvp);
 			vrele(dvp);
+			/*
+			 * Indicate that we released something; see comment
+			 * in smbfs_unmount().
+			 */
+			smp->sm_didrele = 1;
 		} else {
 			VI_UNLOCK(dvp);
 			SMBERROR("BUG: negative use count for parent!\n");
diff --git a/sys/fs/smbfs/smbfs_vfsops.c b/sys/fs/smbfs/smbfs_vfsops.c
index 8dba8c84a525..db0bc8418a50 100644
--- a/sys/fs/smbfs/smbfs_vfsops.c
+++ b/sys/fs/smbfs/smbfs_vfsops.c
@@ -243,8 +243,19 @@ smbfs_unmount(struct mount *mp, int mntflags, struct thread *td)
 	flags = 0;
 	if (mntflags & MNT_FORCE)
 		flags |= FORCECLOSE;
-	/* There is 1 extra root vnode reference from smbfs_mount(). */
-	error = vflush(mp, 1, flags);
+	/*
+	 * Keep trying to flush the vnode list for the mount while 
+	 * some are still busy and we are making progress towards
+	 * making them not busy. This is needed because smbfs vnodes
+	 * reference their parent directory but may appear after their
+	 * parent in the list; one pass over the vnode list is not
+	 * sufficient in this case.
+	 */
+	do {
+		smp->sm_didrele = 0;
+		/* There is 1 extra root vnode reference from smbfs_mount(). */
+		error = vflush(mp, 1, flags);
+	} while (error == EBUSY && smp->sm_didrele != 0);
 	if (error)
 		return error;
 	smb_makescred(&scred, td, td->td_ucred);