Move the head of byte-level advisory lock list from the

filesystem-specific vnode data to the struct vnode. Provide the
default implementation for the vop_advlock and vop_advlockasync.
Purge the locks on the vnode reclaim by using the lf_purgelocks().
The default implementation is augmented for the nfs and smbfs.
In the nfs_advlock, push the Giant inside the nfs_dolock.

Before the change, the vop_advlock and vop_advlockasync have taken the
unlocked vnode and dereferenced the fs-private inode data, racing with
with the vnode reclamation due to forced unmount. Now, the vop_getattr
under the shared vnode lock is used to obtain the inode size, and
later, in the lf_advlockasync, after locking the vnode interlock, the
VI_DOOMED flag is checked to prevent an operation on the doomed vnode.

The implementation of the lf_purgelocks() is submitted by dfr.

Reported by:	kris
Tested by:	kris, pho
Discussed with:	jeff, dfr
MFC after:	2 weeks

2 files changed, 4 insertions, 5 deletions

diff --git a/sys/fs/smbfs/smbfs_node.h b/sys/fs/smbfs/smbfs_node.h
index 4e923936adbb..f9c08cf76f64 100644
--- a/sys/fs/smbfs/smbfs_node.h
+++ b/sys/fs/smbfs/smbfs_node.h
@@ -66,7 +66,6 @@ struct smbnode {
 	u_char *		n_name;
 	struct smbfs_fctx *	n_dirseq;	/* ff context */
 	long			n_dirofs;	/* last ff offset */
-	struct lockf *		n_lockf;	/* Locking records of file */
 	LIST_ENTRY(smbnode)	n_hash;
 };
 
diff --git a/sys/fs/smbfs/smbfs_vnops.c b/sys/fs/smbfs/smbfs_vnops.c
index 4d5f454abf21..f7ca8062806d 100644
--- a/sys/fs/smbfs/smbfs_vnops.c
+++ b/sys/fs/smbfs/smbfs_vnops.c
@@ -1008,7 +1008,7 @@ smbfs_advlock(ap)
 		    default:
 			return EINVAL;
 		}
-		error = lf_advlock(ap, &np->n_lockf, size);
+		error = lf_advlock(ap, &vp->v_lockf, size);
 		if (error)
 			break;
 		lkop = SMB_LOCK_EXCL;
@@ -1017,16 +1017,16 @@ smbfs_advlock(ap)
 			int oldtype = fl->l_type;
 			fl->l_type = F_UNLCK;
 			ap->a_op = F_UNLCK;
-			lf_advlock(ap, &np->n_lockf, size);
+			lf_advlock(ap, &vp->v_lockf, size);
 			fl->l_type = oldtype;
 		}
 		break;
 	    case F_UNLCK:
-		lf_advlock(ap, &np->n_lockf, size);
+		lf_advlock(ap, &vp->v_lockf, size);
 		error = smbfs_smb_lock(np, SMB_LOCK_RELEASE, id, start, end, &scred);
 		break;
 	    case F_GETLK:
-		error = lf_advlock(ap, &np->n_lockf, size);
+		error = lf_advlock(ap, &vp->v_lockf, size);
 		break;
 	    default:
 		return EINVAL;