NFSv4: Follow a referral

Respond to a moved error on NFS lookup by setting up the referral. Note: We don't actually follow the referral during lookup/getattr, but later when we detect fsid mismatch in inode revalidation (similar to the processing done for cloning submounts). Referrals will have fake attributes until they are actually followed or traversed. Signed-off-by: Manoj Naik <manoj@almaden.ibm.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4: Follow a referral
Respond to a moved error on NFS lookup by setting up the referral. Note: We don't actually follow the referral during lookup/getattr, but later when we detect fsid mismatch in inode revalidation (similar to the processing done for cloning submounts). Referrals will have fake attributes until they are actually followed or traversed. Signed-off-by: Manoj Naik <manoj@almaden.ibm.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Manoj Naik · Trond Myklebust
1 parent 9cdb3883c3
Showing 5 changed files with 60 additions and 2 deletions Side-by-side Diff
fs/nfs/inode.c
fs/nfs/namespace.c
fs/nfs/nfs4proc.c
include/linux/nfs_fs.h
include/linux/nfs_xdr.h
@@ -888,7 +888,10 @@
 				set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_FLAGS(inode));
 			/* Deal with crossing mountpoints */
 			if (!nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
-				inode->i_op = &nfs_mountpoint_inode_operations;
+				if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
+					inode->i_op = &nfs_referral_inode_operations;
+				else
+					inode->i_op = &nfs_mountpoint_inode_operations;
 				inode->i_fop = NULL;
 			}
 		} else if (S_ISLNK(inode->i_mode))
@@ -58,7 +58,10 @@
 	if (err != 0)
 		goto out_err;
  
-	mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
+	if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
+		mnt = nfs_do_refmount(nd->mnt, nd->dentry);
+	else
+		mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
 	err = PTR_ERR(mnt);
 	if (IS_ERR(mnt))
 		goto out_err;
@@ -92,6 +95,10 @@
 struct inode_operations nfs_mountpoint_inode_operations = {
 	.follow_link	= nfs_follow_mountpoint,
 	.getattr	= nfs_getattr,
+};
+
+struct inode_operations nfs_referral_inode_operations = {
+	.follow_link	= nfs_follow_mountpoint,
 };
  
 static void nfs_expire_automounts(void *data)
@@ -1462,6 +1462,50 @@
 	return nfs4_map_errors(status);
 }
  
+/*
+ * Get locations and (maybe) other attributes of a referral.
+ * Note that we'll actually follow the referral later when
+ * we detect fsid mismatch in inode revalidation
+ */
+static int nfs4_get_referral(struct inode *dir, struct qstr *name, struct nfs_fattr *fattr, struct nfs_fh *fhandle)
+{
+	int status = -ENOMEM;
+	struct page *page = NULL;
+	struct nfs4_fs_locations *locations = NULL;
+	struct dentry dentry = {};
+
+	page = alloc_page(GFP_KERNEL);
+	if (page == NULL)
+		goto out;
+	locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
+	if (locations == NULL)
+		goto out;
+
+	dentry.d_name.name = name->name;
+	dentry.d_name.len = name->len;
+	status = nfs4_proc_fs_locations(dir, &dentry, locations, page);
+	if (status != 0)
+		goto out;
+	/* Make sure server returned a different fsid for the referral */
+	if (nfs_fsid_equal(&NFS_SERVER(dir)->fsid, &locations->fattr.fsid)) {
+		dprintk("%s: server did not return a different fsid for a referral at %s\n", __FUNCTION__, name->name);
+		status = -EIO;
+		goto out;
+	}
+
+	memcpy(fattr, &locations->fattr, sizeof(struct nfs_fattr));
+	fattr->valid |= NFS_ATTR_FATTR_V4_REFERRAL;
+	if (!fattr->mode)
+		fattr->mode = S_IFDIR;
+	memset(fhandle, 0, sizeof(struct nfs_fh));
+out:
+	if (page)
+		__free_page(page);
+	if (locations)
+		kfree(locations);
+	return status;
+}
+
 static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr)
 {
 	struct nfs4_getattr_arg args = {
@@ -1566,6 +1610,8 @@
  
 	dprintk("NFS call  lookup %s\n", name->name);
 	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
+	if (status == -NFS4ERR_MOVED)
+		status = nfs4_get_referral(dir, name, fattr, fhandle);
 	dprintk("NFS reply lookup: %d\n", status);
 	return status;
 }
@@ -409,6 +409,7 @@
  */
 extern struct list_head nfs_automount_list;
 extern struct inode_operations nfs_mountpoint_inode_operations;
+extern struct inode_operations nfs_referral_inode_operations;
 extern int nfs_mountpoint_expiry_timeout;
 extern void nfs_release_automount_timer(void);
  
@@ -63,6 +63,7 @@
 #define NFS_ATTR_FATTR		0x0002		/* post-op attributes */
 #define NFS_ATTR_FATTR_V3	0x0004		/* NFSv3 attributes */
 #define NFS_ATTR_FATTR_V4	0x0008		/* NFSv4 change attribute */
+#define NFS_ATTR_FATTR_V4_REFERRAL	0x0010		/* NFSv4 referral */
  
 /*
  * Info on the file system
...	...	@@ -888,7 +888,10 @@
888	888	set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_FLAGS(inode));
889	889	/* Deal with crossing mountpoints */
890	890	if (!nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
891		- inode->i_op = &nfs_mountpoint_inode_operations;
	891	+ if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
	892	+ inode->i_op = &nfs_referral_inode_operations;
	893	+ else
	894	+ inode->i_op = &nfs_mountpoint_inode_operations;
892	895	inode->i_fop = NULL;
893	896	}
894	897	} else if (S_ISLNK(inode->i_mode))
...	...	@@ -58,7 +58,10 @@
58	58	if (err != 0)
59	59	goto out_err;
60	60
61		- mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
	61	+ if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
	62	+ mnt = nfs_do_refmount(nd->mnt, nd->dentry);
	63	+ else
	64	+ mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr);
62	65	err = PTR_ERR(mnt);
63	66	if (IS_ERR(mnt))
64	67	goto out_err;
...	...	@@ -92,6 +95,10 @@
92	95	struct inode_operations nfs_mountpoint_inode_operations = {
93	96	.follow_link = nfs_follow_mountpoint,
94	97	.getattr = nfs_getattr,
	98	+};
	99	+
	100	+struct inode_operations nfs_referral_inode_operations = {
	101	+ .follow_link = nfs_follow_mountpoint,
95	102	};
96	103
97	104	static void nfs_expire_automounts(void *data)
...	...	@@ -1462,6 +1462,50 @@
1462	1462	return nfs4_map_errors(status);
1463	1463	}
1464	1464
	1465	+/*
	1466	+ * Get locations and (maybe) other attributes of a referral.
	1467	+ * Note that we'll actually follow the referral later when
	1468	+ * we detect fsid mismatch in inode revalidation
	1469	+ */
	1470	+static int nfs4_get_referral(struct inode dir, struct qstr name, struct nfs_fattr fattr, struct nfs_fh fhandle)
	1471	+{
	1472	+ int status = -ENOMEM;
	1473	+ struct page *page = NULL;
	1474	+ struct nfs4_fs_locations *locations = NULL;
	1475	+ struct dentry dentry = {};
	1476	+
	1477	+ page = alloc_page(GFP_KERNEL);
	1478	+ if (page == NULL)
	1479	+ goto out;
	1480	+ locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
	1481	+ if (locations == NULL)
	1482	+ goto out;
	1483	+
	1484	+ dentry.d_name.name = name->name;
	1485	+ dentry.d_name.len = name->len;
	1486	+ status = nfs4_proc_fs_locations(dir, &dentry, locations, page);
	1487	+ if (status != 0)
	1488	+ goto out;
	1489	+ /* Make sure server returned a different fsid for the referral */
	1490	+ if (nfs_fsid_equal(&NFS_SERVER(dir)->fsid, &locations->fattr.fsid)) {
	1491	+ dprintk("%s: server did not return a different fsid for a referral at %s\n", __FUNCTION__, name->name);
	1492	+ status = -EIO;
	1493	+ goto out;
	1494	+ }
	1495	+
	1496	+ memcpy(fattr, &locations->fattr, sizeof(struct nfs_fattr));
	1497	+ fattr->valid \|= NFS_ATTR_FATTR_V4_REFERRAL;
	1498	+ if (!fattr->mode)
	1499	+ fattr->mode = S_IFDIR;
	1500	+ memset(fhandle, 0, sizeof(struct nfs_fh));
	1501	+out:
	1502	+ if (page)
	1503	+ __free_page(page);
	1504	+ if (locations)
	1505	+ kfree(locations);
	1506	+ return status;
	1507	+}
	1508	+
1465	1509	static int _nfs4_proc_getattr(struct nfs_server server, struct nfs_fh fhandle, struct nfs_fattr *fattr)
1466	1510	{
1467	1511	struct nfs4_getattr_arg args = {
...	...	@@ -1566,6 +1610,8 @@
1566	1610
1567	1611	dprintk("NFS call lookup %s\n", name->name);
1568	1612	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
	1613	+ if (status == -NFS4ERR_MOVED)
	1614	+ status = nfs4_get_referral(dir, name, fattr, fhandle);
1569	1615	dprintk("NFS reply lookup: %d\n", status);
1570	1616	return status;
1571	1617	}
...	...	@@ -409,6 +409,7 @@
409	409	*/
410	410	extern struct list_head nfs_automount_list;
411	411	extern struct inode_operations nfs_mountpoint_inode_operations;
	412	+extern struct inode_operations nfs_referral_inode_operations;
412	413	extern int nfs_mountpoint_expiry_timeout;
413	414	extern void nfs_release_automount_timer(void);
414	415
...	...	@@ -63,6 +63,7 @@
63	63	#define NFS_ATTR_FATTR 0x0002 /* post-op attributes */
64	64	#define NFS_ATTR_FATTR_V3 0x0004 /* NFSv3 attributes */
65	65	#define NFS_ATTR_FATTR_V4 0x0008 /* NFSv4 change attribute */
	66	+#define NFS_ATTR_FATTR_V4_REFERRAL 0x0010 /* NFSv4 referral */
66	67
67	68	/*
68	69	* Info on the file system