nfsd: allow layout state to be admin-revoked.

When there is layout state on a filesystem that is being "unlocked" that
is now revoked, which involves closing the nfsd_file and releasing the
vfs lease.

To avoid races, ->ls_file can now be accessed either:
 - under ->fi_lock for the state's sc_file or
 - under rcu_read_lock() if nfsd_file_get() is used.
To support this, ->fence_client and nfsd4_cb_layout_fail() now take a
second argument being the nfsd_file.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/blocklayout.c

@@ -328,10 +328,10 @@ nfsd4_scsi_proc_layoutcommit(struct inode *inode,
 }
 
 static void
-nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls)
+nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
 {
 	struct nfs4_client *clp = ls->ls_stid.sc_client;
-	struct block_device *bdev = ls->ls_file->nf_file->f_path.mnt->mnt_sb->s_bdev;
+	struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;
 
 	bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
 			nfsd4_scsi_pr_key(clp), 0, true);

fs/nfsd/nfs4layouts.c

@@ -152,6 +152,23 @@ void nfsd4_setup_layout_type(struct svc_export *exp)
 #endif
 }
 
+void nfsd4_close_layout(struct nfs4_layout_stateid *ls)
+{
+	struct nfsd_file *fl;
+
+	spin_lock(&ls->ls_stid.sc_file->fi_lock);
+	fl = ls->ls_file;
+	ls->ls_file = NULL;
+	spin_unlock(&ls->ls_stid.sc_file->fi_lock);
+
+	if (fl) {
+		if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
+			vfs_setlease(fl->nf_file, F_UNLCK, NULL,
+				     (void **)&ls);
+		nfsd_file_put(fl);
+	}
+}
+
 static void
 nfsd4_free_layout_stateid(struct nfs4_stid *stid)
 {
@@ -169,9 +186,7 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid)
 	list_del_init(&ls->ls_perfile);
 	spin_unlock(&fp->fi_lock);
 
-	if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
-		vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls);
-	nfsd_file_put(ls->ls_file);
+	nfsd4_close_layout(ls);
 
 	if (ls->ls_recalled)
 		atomic_dec(&ls->ls_stid.sc_file->fi_lo_recalls);
@@ -605,7 +620,7 @@ nfsd4_return_all_file_layouts(struct nfs4_client *clp, struct nfs4_file *fp)
 }
 
 static void
-nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
+nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
 {
 	struct nfs4_client *clp = ls->ls_stid.sc_client;
 	char addr_str[INET6_ADDRSTRLEN];
@@ -627,7 +642,7 @@ nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
 
 	argv[0] = (char *)nfsd_recall_failed;
 	argv[1] = addr_str;
-	argv[2] = ls->ls_file->nf_file->f_path.mnt->mnt_sb->s_id;
+	argv[2] = file->nf_file->f_path.mnt->mnt_sb->s_id;
 	argv[3] = NULL;
 
 	error = call_usermodehelper(nfsd_recall_failed, argv, envp,
@@ -657,6 +672,7 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
 	struct nfsd_net *nn;
 	ktime_t now, cutoff;
 	const struct nfsd4_layout_ops *ops;
+	struct nfsd_file *fl;
 
 	trace_nfsd_cb_layout_done(&ls->ls_stid.sc_stateid, task);
 	switch (task->tk_status) {
@@ -688,12 +704,17 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
 		 * Unknown error or non-responding client, we'll need to fence.
 		 */
 		trace_nfsd_layout_recall_fail(&ls->ls_stid.sc_stateid);
-
-		ops = nfsd4_layout_ops[ls->ls_layout_type];
-		if (ops->fence_client)
-			ops->fence_client(ls);
-		else
-			nfsd4_cb_layout_fail(ls);
+		rcu_read_lock();
+		fl = nfsd_file_get(ls->ls_file);
+		rcu_read_unlock();
+		if (fl) {
+			ops = nfsd4_layout_ops[ls->ls_layout_type];
+			if (ops->fence_client)
+				ops->fence_client(ls, fl);
+			else
+				nfsd4_cb_layout_fail(ls, fl);
+			nfsd_file_put(fl);
+		}
 		return 1;
 	case -NFS4ERR_NOMATCHING_LAYOUT:
 		trace_nfsd_layout_recall_done(&ls->ls_stid.sc_stateid);

fs/nfsd/nfs4state.c

@@ -1721,7 +1721,7 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
 	unsigned int idhashval;
 	unsigned int sc_types;
 
-	sc_types = SC_TYPE_OPEN | SC_TYPE_LOCK | SC_TYPE_DELEG;
+	sc_types = SC_TYPE_OPEN | SC_TYPE_LOCK | SC_TYPE_DELEG | SC_TYPE_LAYOUT;
 
 	spin_lock(&nn->client_lock);
 	for (idhashval = 0; idhashval < CLIENT_HASH_MASK; idhashval++) {
@@ -1734,6 +1734,7 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
 			if (stid) {
 				struct nfs4_ol_stateid *stp;
 				struct nfs4_delegation *dp;
+				struct nfs4_layout_stateid *ls;
 
 				spin_unlock(&nn->client_lock);
 				switch (stid->sc_type) {
@@ -1789,6 +1790,10 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
 					if (dp)
 						revoke_delegation(dp);
 					break;
+				case SC_TYPE_LAYOUT:
+					ls = layoutstateid(stid);
+					nfsd4_close_layout(ls);
+					break;
 				}
 				nfs4_put_stid(stid);
 				spin_lock(&nn->client_lock);
@@ -2868,7 +2873,6 @@ static int nfs4_show_layout(struct seq_file *s, struct nfs4_stid *st)
 	struct nfsd_file *file;
 
 	ls = container_of(st, struct nfs4_layout_stateid, ls_stid);
-	file = ls->ls_file;
 
 	seq_puts(s, "- ");
 	nfs4_show_stateid(s, &st->sc_stateid);
@@ -2876,12 +2880,15 @@ static int nfs4_show_layout(struct seq_file *s, struct nfs4_stid *st)
 
 	/* XXX: What else would be useful? */
 
+	spin_lock(&ls->ls_stid.sc_file->fi_lock);
+	file = ls->ls_file;
 	if (file) {
 		seq_puts(s, ", ");
 		nfs4_show_superblock(s, file);
 		seq_puts(s, ", ");
 		nfs4_show_fname(s, file);
 	}
+	spin_unlock(&ls->ls_stid.sc_file->fi_lock);
 	if (st->sc_status & SC_STATUS_ADMIN_REVOKED)
 		seq_puts(s, ", admin-revoked");
 	seq_puts(s, " }\n");

fs/nfsd/pnfs.h

@@ -37,7 +37,8 @@ struct nfsd4_layout_ops {
 	__be32 (*proc_layoutcommit)(struct inode *inode,
 			struct nfsd4_layoutcommit *lcp);
 
-	void (*fence_client)(struct nfs4_layout_stateid *ls);
+	void (*fence_client)(struct nfs4_layout_stateid *ls,
+			     struct nfsd_file *file);
 };
 
 extern const struct nfsd4_layout_ops *nfsd4_layout_ops[];
@@ -72,11 +73,13 @@ void nfsd4_setup_layout_type(struct svc_export *exp);
 void nfsd4_return_all_client_layouts(struct nfs4_client *);
 void nfsd4_return_all_file_layouts(struct nfs4_client *clp,
 		struct nfs4_file *fp);
+void nfsd4_close_layout(struct nfs4_layout_stateid *ls);
 int nfsd4_init_pnfs(void);
 void nfsd4_exit_pnfs(void);
 #else
 struct nfs4_client;
 struct nfs4_file;
+struct nfs4_layout_stateid;
 
 static inline void nfsd4_setup_layout_type(struct svc_export *exp)
 {
@@ -89,6 +92,9 @@ static inline void nfsd4_return_all_file_layouts(struct nfs4_client *clp,
 		struct nfs4_file *fp)
 {
 }
+static inline void nfsd4_close_layout(struct nfs4_layout_stateid *ls)
+{
+}
 static inline void nfsd4_exit_pnfs(void)
 {
 }