NFS: Share NFS superblocks per-protocol per-server per-FSID

The attached patch makes NFS share superblocks between mounts from the same
server and FSID over the same protocol.

It does this by creating each superblock with a false root and returning the
real root dentry in the vfsmount presented by get_sb(). The root dentry set
starts off as an anonymous dentry if we don't already have the dentry for its
inode, otherwise it simply returns the dentry we already have.

We may thus end up with several trees of dentries in the superblock, and if at
some later point one of anonymous tree roots is discovered by normal filesystem
activity to be located in another tree within the superblock, the anonymous
root is named and materialises attached to the second tree at the appropriate
point.

Why do it this way? Why not pass an extra argument to the mount() syscall to
indicate the subpath and then pathwalk from the server root to the desired
directory? You can't guarantee this will work for two reasons:

 (1) The root and intervening nodes may not be accessible to the client.

     With NFS2 and NFS3, for instance, mountd is called on the server to get
     the filehandle for the tip of a path. mountd won't give us handles for
     anything we don't have permission to access, and so we can't set up NFS
     inodes for such nodes, and so can't easily set up dentries (we'd have to
     have ghost inodes or something).

     With this patch we don't actually create dentries until we get handles
     from the server that we can use to set up their inodes, and we don't
     actually bind them into the tree until we know for sure where they go.

 (2) Inaccessible symbolic links.

     If we're asked to mount two exports from the server, eg:

	mount warthog:/warthog/aaa/xxx /mmm
	mount warthog:/warthog/bbb/yyy /nnn

     We may not be able to access anything nearer the root than xxx and yyy,
     but we may find out later that /mmm/www/yyy, say, is actually the same
     directory as the one mounted on /nnn. What we might then find out, for
     example, is that /warthog/bbb was actually a symbolic link to
     /warthog/aaa/xxx/www, but we can't actually determine that by talking to
     the server until /warthog is made available by NFS.

     This would lead to having constructed an errneous dentry tree which we
     can't easily fix. We can end up with a dentry marked as a directory when
     it should actually be a symlink, or we could end up with an apparently
     hardlinked directory.

     With this patch we need not make assumptions about the type of a dentry
     for which we can't retrieve information, nor need we assume we know its
     place in the grand scheme of things until we actually see that place.

This patch reduces the possibility of aliasing in the inode and page caches for
inodes that may be accessed by more than one NFS export. It also reduces the
number of superblocks required for NFS where there are many NFS exports being
used from a server (home directory server + autofs for example).

This in turn makes it simpler to do local caching of network filesystems, as it
can then be guaranteed that there won't be links from multiple inodes in
separate superblocks to the same cache file.

Obviously, cache aliasing between different levels of NFS protocol could still
be a problem, but at least that gives us another key to use when indexing the
cache.

This patch makes the following changes:

 (1) The server record construction/destruction has been abstracted out into
     its own set of functions to make things easier to get right.  These have
     been moved into fs/nfs/client.c.

     All the code in fs/nfs/client.c has to do with the management of
     connections to servers, and doesn't touch superblocks in any way; the
     remaining code in fs/nfs/super.c has to do with VFS superblock management.

 (2) The sequence of events undertaken by NFS mount is now reordered:

     (a) A volume representation (struct nfs_server) is allocated.

     (b) A server representation (struct nfs_client) is acquired.  This may be
     	 allocated or shared, and is keyed on server address, port and NFS
     	 version.

     (c) If allocated, the client representation is initialised.  The state
     	 member variable of nfs_client is used to prevent a race during
     	 initialisation from two mounts.

     (d) For NFS4 a simple pathwalk is performed, walking from FH to FH to find
     	 the root filehandle for the mount (fs/nfs/getroot.c).  For NFS2/3 we
     	 are given the root FH in advance.

     (e) The volume FSID is probed for on the root FH.

     (f) The volume representation is initialised from the FSINFO record
     	 retrieved on the root FH.

     (g) sget() is called to acquire a superblock.  This may be allocated or
     	 shared, keyed on client pointer and FSID.

     (h) If allocated, the superblock is initialised.

     (i) If the superblock is shared, then the new nfs_server record is
     	 discarded.

     (j) The root dentry for this mount is looked up from the root FH.

     (k) The root dentry for this mount is assigned to the vfsmount.

 (3) nfs_readdir_lookup() creates dentries for each of the entries readdir()
     returns; this function now attaches disconnected trees from alternate
     roots that happen to be discovered attached to a directory being read (in
     the same way nfs_lookup() is made to do for lookup ops).

     The new d_materialise_unique() function is now used to do this, thus
     permitting the whole thing to be done under one set of locks, and thus
     avoiding any race between mount and lookup operations on the same
     directory.

 (4) The client management code uses a new debug facility: NFSDBG_CLIENT which
     is set by echoing 1024 to /proc/net/sunrpc/nfs_debug.

 (5) Clone mounts are now called xdev mounts.

 (6) Use the dentry passed to the statfs() op as the handle for retrieving fs
     statistics rather than the root dentry of the superblock (which is now a
     dummy).
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/Makefile

@@ -4,7 +4,7 @@
 
 obj-$(CONFIG_NFS_FS) += nfs.o
 
-nfs-y 			:= client.o dir.o file.o inode.o super.o nfs2xdr.o \
+nfs-y 			:= client.o dir.o file.o getroot.o inode.o super.o nfs2xdr.o \
 			   pagelist.o proc.o read.o symlink.o unlink.o \
 			   write.o namespace.o
 nfs-$(CONFIG_ROOT_NFS)	+= nfsroot.o mount_clnt.o      

fs/nfs/dir.c

@@ -31,6 +31,7 @@
 #include <linux/pagemap.h>
 #include <linux/smp_lock.h>
 #include <linux/namei.h>
+#include <linux/mount.h>
 
 #include "nfs4_fs.h"
 #include "delegation.h"
@@ -870,14 +871,14 @@ int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
 	return (nd->intent.open.flags & O_EXCL) != 0;
 }
 
-static inline int nfs_reval_fsid(struct inode *dir,
-		struct nfs_fh *fh, struct nfs_fattr *fattr)
+static inline int nfs_reval_fsid(struct vfsmount *mnt, struct inode *dir,
+				 struct nfs_fh *fh, struct nfs_fattr *fattr)
 {
 	struct nfs_server *server = NFS_SERVER(dir);
 
 	if (!nfs_fsid_equal(&server->fsid, &fattr->fsid))
 		/* Revalidate fsid on root dir */
-		return __nfs_revalidate_inode(server, dir->i_sb->s_root->d_inode);
+		return __nfs_revalidate_inode(server, mnt->mnt_root->d_inode);
 	return 0;
 }
 
@@ -913,7 +914,7 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
 		res = ERR_PTR(error);
 		goto out_unlock;
 	}
-	error = nfs_reval_fsid(dir, &fhandle, &fattr);
+	error = nfs_reval_fsid(nd->mnt, dir, &fhandle, &fattr);
 	if (error < 0) {
 		res = ERR_PTR(error);
 		goto out_unlock;
@@ -922,8 +923,9 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
 	res = (struct dentry *)inode;
 	if (IS_ERR(res))
 		goto out_unlock;
+
 no_entry:
-	res = d_add_unique(dentry, inode);
+	res = d_materialise_unique(dentry, inode);
 	if (res != NULL)
 		dentry = res;
 	nfs_renew_times(dentry);
@@ -1117,11 +1119,13 @@ static struct dentry *nfs_readdir_lookup(nfs_readdir_descriptor_t *desc)
 		dput(dentry);
 		return NULL;
 	}
-	alias = d_add_unique(dentry, inode);
+
+	alias = d_materialise_unique(dentry, inode);
 	if (alias != NULL) {
 		dput(dentry);
 		dentry = alias;
 	}
+
 	nfs_renew_times(dentry);
 	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
 	return dentry;

fs/nfs/getroot.c

+/* getroot.c: get the root dentry for an NFS mount
+ *
+ * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include <linux/time.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/stats.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+#include <linux/nfs4_mount.h>
+#include <linux/lockd/bind.h>
+#include <linux/smp_lock.h>
+#include <linux/seq_file.h>
+#include <linux/mount.h>
+#include <linux/nfs_idmap.h>
+#include <linux/vfs.h>
+#include <linux/namei.h>
+#include <linux/namespace.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+#include "nfs4_fs.h"
+#include "delegation.h"
+#include "internal.h"
+
+#define NFSDBG_FACILITY		NFSDBG_CLIENT
+#define NFS_PARANOIA 1
+
+/*
+ * get an NFS2/NFS3 root dentry from the root filehandle
+ */
+struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
+{
+	struct nfs_server *server = NFS_SB(sb);
+	struct nfs_fsinfo fsinfo;
+	struct nfs_fattr fattr;
+	struct dentry *mntroot;
+	struct inode *inode;
+	int error;
+
+	/* create a dummy root dentry with dummy inode for this superblock */
+	if (!sb->s_root) {
+		struct nfs_fh dummyfh;
+		struct dentry *root;
+		struct inode *iroot;
+
+		memset(&dummyfh, 0, sizeof(dummyfh));
+		memset(&fattr, 0, sizeof(fattr));
+		nfs_fattr_init(&fattr);
+		fattr.valid = NFS_ATTR_FATTR;
+		fattr.type = NFDIR;
+		fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;
+		fattr.nlink = 2;
+
+		iroot = nfs_fhget(sb, &dummyfh, &fattr);
+		if (IS_ERR(iroot))
+			return ERR_PTR(PTR_ERR(iroot));
+
+		root = d_alloc_root(iroot);
+		if (!root) {
+			iput(iroot);
+			return ERR_PTR(-ENOMEM);
+		}
+
+		sb->s_root = root;
+	}
+
+	/* get the actual root for this mount */
+	fsinfo.fattr = &fattr;
+
+	error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
+	if (error < 0) {
+		dprintk("nfs_get_root: getattr error = %d\n", -error);
+		return ERR_PTR(error);
+	}
+
+	inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
+	if (IS_ERR(inode)) {
+		dprintk("nfs_get_root: get root inode failed\n");
+		return ERR_PTR(PTR_ERR(inode));
+	}
+
+	/* root dentries normally start off anonymous and get spliced in later
+	 * if the dentry tree reaches them; however if the dentry already
+	 * exists, we'll pick it up at this point and use it as the root
+	 */
+	mntroot = d_alloc_anon(inode);
+	if (!mntroot) {
+		iput(inode);
+		dprintk("nfs_get_root: get root dentry failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	if (!mntroot->d_op)
+		mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
+
+	return mntroot;
+}
+
+#ifdef CONFIG_NFS_V4
+
+/*
+ * Do a simple pathwalk from the root FH of the server to the nominated target
+ * of the mountpoint
+ * - give error on symlinks
+ * - give error on ".." occurring in the path
+ * - follow traversals
+ */
+int nfs4_path_walk(struct nfs_server *server,
+		   struct nfs_fh *mntfh,
+		   const char *path)
+{
+	struct nfs_fsinfo fsinfo;
+	struct nfs_fattr fattr;
+	struct nfs_fh lastfh;
+	struct qstr name;
+	int ret;
+	//int referral_count = 0;
+
+	dprintk("--> nfs4_path_walk(,,%s)\n", path);
+
+	fsinfo.fattr = &fattr;
+	nfs_fattr_init(&fattr);
+
+	if (*path++ != '/') {
+		dprintk("nfs4_get_root: Path does not begin with a slash\n");
+		return -EINVAL;
+	}
+
+	/* Start by getting the root filehandle from the server */
+	ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
+	if (ret < 0) {
+		dprintk("nfs4_get_root: getroot error = %d\n", -ret);
+		return ret;
+	}
+
+	if (fattr.type != NFDIR) {
+		printk(KERN_ERR "nfs4_get_root:"
+		       " getroot encountered non-directory\n");
+		return -ENOTDIR;
+	}
+
+	if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
+		printk(KERN_ERR "nfs4_get_root:"
+		       " getroot obtained referral\n");
+		return -EREMOTE;
+	}
+
+next_component:
+	dprintk("Next: %s\n", path);
+
+	/* extract the next bit of the path */
+	if (!*path)
+		goto path_walk_complete;
+
+	name.name = path;
+	while (*path && *path != '/')
+		path++;
+	name.len = path - (const char *) name.name;
+
+eat_dot_dir:
+	while (*path == '/')
+		path++;
+
+	if (path[0] == '.' && (path[1] == '/' || !path[1])) {
+		path += 2;
+		goto eat_dot_dir;
+	}
+
+	if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2])
+	    ) {
+		printk(KERN_ERR "nfs4_get_root:"
+		       " Mount path contains reference to \"..\"\n");
+		return -EINVAL;
+	}
+
+	/* lookup the next FH in the sequence */
+	memcpy(&lastfh, mntfh, sizeof(lastfh));
+
+	dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path);
+
+	ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name,
+						    mntfh, &fattr);
+	if (ret < 0) {
+		dprintk("nfs4_get_root: getroot error = %d\n", -ret);
+		return ret;
+	}
+
+	if (fattr.type != NFDIR) {
+		printk(KERN_ERR "nfs4_get_root:"
+		       " lookupfh encountered non-directory\n");
+		return -ENOTDIR;
+	}
+
+	if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
+		printk(KERN_ERR "nfs4_get_root:"
+		       " lookupfh obtained referral\n");
+		return -EREMOTE;
+	}
+
+	goto next_component;
+
+path_walk_complete:
+	memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid));
+	dprintk("<-- nfs4_path_walk() = 0\n");
+	return 0;
+}
+
+/*
+ * get an NFS4 root dentry from the root filehandle
+ */
+struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
+{
+	struct nfs_server *server = NFS_SB(sb);
+	struct nfs_fattr fattr;
+	struct dentry *mntroot;
+	struct inode *inode;
+	int error;
+
+	dprintk("--> nfs4_get_root()\n");
+
+	/* create a dummy root dentry with dummy inode for this superblock */
+	if (!sb->s_root) {
+		struct nfs_fh dummyfh;
+		struct dentry *root;
+		struct inode *iroot;
+
+		memset(&dummyfh, 0, sizeof(dummyfh));
+		memset(&fattr, 0, sizeof(fattr));
+		nfs_fattr_init(&fattr);
+		fattr.valid = NFS_ATTR_FATTR;
+		fattr.type = NFDIR;
+		fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;
+		fattr.nlink = 2;
+
+		iroot = nfs_fhget(sb, &dummyfh, &fattr);
+		if (IS_ERR(iroot))
+			return ERR_PTR(PTR_ERR(iroot));
+
+		root = d_alloc_root(iroot);
+		if (!root) {
+			iput(iroot);
+			return ERR_PTR(-ENOMEM);
+		}
+
+		sb->s_root = root;
+	}
+
+	/* get the info about the server and filesystem */
+	error = nfs4_server_capabilities(server, mntfh);
+	if (error < 0) {
+		dprintk("nfs_get_root: getcaps error = %d\n",
+			-error);
+		return ERR_PTR(error);
+	}
+
+	/* get the actual root for this mount */
+	error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
+	if (error < 0) {
+		dprintk("nfs_get_root: getattr error = %d\n", -error);
+		return ERR_PTR(error);
+	}
+
+	inode = nfs_fhget(sb, mntfh, &fattr);
+	if (IS_ERR(inode)) {
+		dprintk("nfs_get_root: get root inode failed\n");
+		return ERR_PTR(PTR_ERR(inode));
+	}
+
+	/* root dentries normally start off anonymous and get spliced in later
+	 * if the dentry tree reaches them; however if the dentry already
+	 * exists, we'll pick it up at this point and use it as the root
+	 */
+	mntroot = d_alloc_anon(inode);
+	if (!mntroot) {
+		iput(inode);
+		dprintk("nfs_get_root: get root dentry failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	if (!mntroot->d_op)
+		mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
+
+	dprintk("<-- nfs4_get_root()\n");
+	return mntroot;
+}
+
+#endif /* CONFIG_NFS_V4 */

fs/nfs/idmap.c

@@ -114,8 +114,7 @@ nfs_idmap_new(struct nfs_client *clp)
 	struct idmap *idmap;
 	int error;
 
-	if (clp->cl_idmap != NULL)
-		return 0;
+	BUG_ON(clp->cl_idmap != NULL);
 
         if ((idmap = kzalloc(sizeof(*idmap), GFP_KERNEL)) == NULL)
                 return -ENOMEM;

fs/nfs/inode.c

@@ -1020,7 +1020,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  out_fileid:
 	printk(KERN_ERR "NFS: server %s error: fileid changed\n"
 		"fsid %s: expected fileid 0x%Lx, got 0x%Lx\n",
-		NFS_SERVER(inode)->hostname, inode->i_sb->s_id,
+		NFS_SERVER(inode)->nfs_client->cl_hostname, inode->i_sb->s_id,
 		(long long)nfsi->fileid, (long long)fattr->fileid);
 	goto out_err;
 }

fs/nfs/internal.h

@@ -4,6 +4,18 @@
 
 #include <linux/mount.h>
 
+struct nfs_string;
+struct nfs_mount_data;
+struct nfs4_mount_data;
+
+/* Maximum number of readahead requests
+ * FIXME: this should really be a sysctl so that users may tune it to suit
+ *        their needs. People that do NFS over a slow network, might for
+ *        instance want to reduce it to something closer to 1 for improved
+ *        interactive response.
+ */
+#define NFS_MAX_READAHEAD	(RPC_DEF_SLOT_TABLE - 1)
+
 struct nfs_clone_mount {
 	const struct super_block *sb;
 	const struct dentry *dentry;
@@ -16,12 +28,25 @@ struct nfs_clone_mount {
 };
 
 /* client.c */
+extern struct rpc_program nfs_program;
+
 extern void nfs_put_client(struct nfs_client *);
 extern struct nfs_client *nfs_find_client(const struct sockaddr_in *, int);
-extern struct nfs_client *nfs_get_client(const char *, const struct sockaddr_in *, int);
-extern void nfs_mark_client_ready(struct nfs_client *, int);
-extern int nfs_create_rpc_client(struct nfs_client *, int, unsigned int,
-				 unsigned int, rpc_authflavor_t);
+extern struct nfs_server *nfs_create_server(const struct nfs_mount_data *,
+					    struct nfs_fh *);
+extern struct nfs_server *nfs4_create_server(const struct nfs4_mount_data *,
+					     const char *,
+					     const struct sockaddr_in *,
+					     const char *,
+					     const char *,
+					     rpc_authflavor_t,
+					     struct nfs_fh *);
+extern struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *,
+						      struct nfs_fh *);
+extern void nfs_free_server(struct nfs_server *server);
+extern struct nfs_server *nfs_clone_server(struct nfs_server *,
+					   struct nfs_fh *,
+					   struct nfs_fattr *);
 
 /* nfs4namespace.c */
 #ifdef CONFIG_NFS_V4
@@ -89,10 +114,10 @@ extern void nfs4_clear_inode(struct inode *);
 #endif
 
 /* super.c */
-extern struct file_system_type nfs_referral_nfs4_fs_type;
-extern struct file_system_type clone_nfs_fs_type;
+extern struct file_system_type nfs_xdev_fs_type;
 #ifdef CONFIG_NFS_V4
-extern struct file_system_type clone_nfs4_fs_type;
+extern struct file_system_type nfs4_xdev_fs_type;
+extern struct file_system_type nfs4_referral_fs_type;
 #endif
 
 extern struct rpc_stat nfs_rpcstat;
@@ -101,28 +126,30 @@ extern int __init register_nfs_fs(void);
 extern void __exit unregister_nfs_fs(void);
 
 /* namespace.c */
-extern char *nfs_path(const char *base, const struct dentry *dentry,
+extern char *nfs_path(const char *base,
+		      const struct dentry *droot,
+		      const struct dentry *dentry,
 		      char *buffer, ssize_t buflen);
 
-/*
- * Determine the mount path as a string
- */
+/* getroot.c */
+extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *);
 #ifdef CONFIG_NFS_V4
-static inline char *
-nfs4_path(const struct dentry *dentry, char *buffer, ssize_t buflen)
-{
-	return nfs_path(NFS_SB(dentry->d_sb)->mnt_path, dentry, buffer, buflen);
-}
+extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *);
+
+extern int nfs4_path_walk(struct nfs_server *server,
+			  struct nfs_fh *mntfh,
+			  const char *path);
 #endif
 
 /*
  * Determine the device name as a string
  */
 static inline char *nfs_devname(const struct vfsmount *mnt_parent,
-			 const struct dentry *dentry,
-			 char *buffer, ssize_t buflen)
+				const struct dentry *dentry,
+				char *buffer, ssize_t buflen)
 {
-	return nfs_path(mnt_parent->mnt_devname, dentry, buffer, buflen);
+	return nfs_path(mnt_parent->mnt_devname, mnt_parent->mnt_root,
+			dentry, buffer, buflen);
 }
 
 /*
@@ -178,20 +205,3 @@ void nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
 	if (sb->s_maxbytes > MAX_LFS_FILESIZE || sb->s_maxbytes <= 0)
 		sb->s_maxbytes = MAX_LFS_FILESIZE;
 }
-
-/*
- * Check if the string represents a "valid" IPv4 address
- */
-static inline int valid_ipaddr4(const char *buf)
-{
-	int rc, count, in[4];
-
-	rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
-	if (rc != 4)
-		return -EINVAL;
-	for (count = 0; count < 4; count++) {
-		if (in[count] > 255)
-			return -EINVAL;
-	}
-	return 0;
-}

fs/nfs/namespace.c

@@ -2,6 +2,7 @@
  * linux/fs/nfs/namespace.c
  *
  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
+ * - Modified by David Howells <dhowells@redhat.com>
  *
  * NFS namespace
  */
@@ -28,6 +29,7 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
 /*
  * nfs_path - reconstruct the path given an arbitrary dentry
  * @base - arbitrary string to prepend to the path
+ * @droot - pointer to root dentry for mountpoint
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
@@ -38,7 +40,9 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * This is mainly for use in figuring out the path on the
  * server side when automounting on top of an existing partition.
  */
-char *nfs_path(const char *base, const struct dentry *dentry,
+char *nfs_path(const char *base,
+	       const struct dentry *droot,
+	       const struct dentry *dentry,
 	       char *buffer, ssize_t buflen)
 {
 	char *end = buffer+buflen;
@@ -47,7 +51,7 @@ char *nfs_path(const char *base, const struct dentry *dentry,
 	*--end = '\0';
 	buflen--;
 	spin_lock(&dcache_lock);
-	while (!IS_ROOT(dentry)) {
+	while (!IS_ROOT(dentry) && dentry != droot) {
 		namelen = dentry->d_name.len;
 		buflen -= namelen + 1;
 		if (buflen < 0)
@@ -96,12 +100,13 @@ static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 	struct nfs_fattr fattr;
 	int err;
 
+	dprintk("--> nfs_follow_mountpoint()\n");
+
 	BUG_ON(IS_ROOT(dentry));
 	dprintk("%s: enter\n", __FUNCTION__);
 	dput(nd->dentry);
 	nd->dentry = dget(dentry);
-	if (d_mountpoint(nd->dentry))
-		goto out_follow;
+
 	/* Look it up again */
 	parent = dget_parent(nd->dentry);
 	err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
@@ -134,6 +139,8 @@ static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
 out:
 	dprintk("%s: done, returned %d\n", __FUNCTION__, err);
+
+	dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
 	return ERR_PTR(err);
 out_err:
 	path_release(nd);
@@ -183,14 +190,14 @@ static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
 	switch (server->nfs_client->cl_nfsversion) {
 		case 2:
 		case 3:
-			mnt = vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata);
+			mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
 			break;
 		case 4:
-			mnt = vfs_kern_mount(&clone_nfs4_fs_type, 0, devname, mountdata);
+			mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
 	}
 	return mnt;
 #else
-	return vfs_kern_mount(&clone_nfs_fs_type, 0, devname, mountdata);
+	return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
 #endif
 }
 
@@ -216,6 +223,8 @@ struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
 	char *page = (char *) __get_free_page(GFP_USER);
 	char *devname;
 
+	dprintk("--> nfs_do_submount()\n");
+
 	dprintk("%s: submounting on %s/%s\n", __FUNCTION__,
 			dentry->d_parent->d_name.name,
 			dentry->d_name.name);
@@ -230,5 +239,7 @@ struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
 	free_page((unsigned long)page);
 out:
 	dprintk("%s: done\n", __FUNCTION__);
+
+	dprintk("<-- nfs_do_submount() = %p\n", mnt);
 	return mnt;
 }

fs/nfs/nfs3proc.c

@@ -81,7 +81,7 @@ do_proc_get_root(struct rpc_clnt *client, struct nfs_fh *fhandle,
 }
 
 /*
- * Bare-bones access to getattr: this is for nfs_read_super.
+ * Bare-bones access to getattr: this is for nfs_get_root/nfs_get_sb
  */
 static int
 nfs3_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,

fs/nfs/nfs4_fs.h

@@ -188,8 +188,6 @@ extern void nfs4_kill_renewd(struct nfs_client *);
 extern void nfs4_renew_state(void *);
 
 /* nfs4state.c */
-extern void init_nfsv4_state(struct nfs_server *);
-extern void destroy_nfsv4_state(struct nfs_server *);
 struct rpc_cred *nfs4_get_renew_cred(struct nfs_client *clp);
 extern u32 nfs4_alloc_lockowner_id(struct nfs_client *);
 
@@ -224,10 +222,6 @@ extern struct svc_version nfs4_callback_version1;
 
 #else
 
-#define init_nfsv4_state(server)  do { } while (0)
-#define destroy_nfsv4_state(server)       do { } while (0)
-#define nfs4_put_state_owner(inode, owner) do { } while (0)
-#define nfs4_put_open_state(state) do { } while (0)
 #define nfs4_close_state(a, b) do { } while (0)
 
 #endif /* CONFIG_NFS_V4 */

fs/nfs/nfs4namespace.c

@@ -2,6 +2,7 @@
  * linux/fs/nfs/nfs4namespace.c
  *
  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
+ * - Modified by David Howells <dhowells@redhat.com>
  *
  * NFSv4 namespace
  */
@@ -47,6 +48,68 @@ static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
 	return ERR_PTR(-ENAMETOOLONG);
 }
 
+/*
+ * Determine the mount path as a string
+ */
+static char *nfs4_path(const struct vfsmount *mnt_parent,
+		       const struct dentry *dentry,
+		       char *buffer, ssize_t buflen)
+{
+	const char *srvpath;
+
+	srvpath = strchr(mnt_parent->mnt_devname, ':');
+	if (srvpath)
+		srvpath++;
+	else
+		srvpath = mnt_parent->mnt_devname;
+
+	return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
+}
+
+/*
+ * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
+ * believe to be the server path to this dentry
+ */
+static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
+				const struct dentry *dentry,
+				const struct nfs4_fs_locations *locations,
+				char *page, char *page2)
+{
+	const char *path, *fs_path;
+
+	path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+
+	fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
+	if (IS_ERR(fs_path))
+		return PTR_ERR(fs_path);
+
+	if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
+		dprintk("%s: path %s does not begin with fsroot %s\n",
+			__FUNCTION__, path, fs_path);
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
+/*
+ * Check if the string represents a "valid" IPv4 address
+ */
+static inline int valid_ipaddr4(const char *buf)
+{
+	int rc, count, in[4];
+
+	rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
+	if (rc != 4)
+		return -EINVAL;
+	for (count = 0; count < 4; count++) {
+		if (in[count] > 255)
+			return -EINVAL;
+	}
+	return 0;
+}
 
 /**
  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
@@ -68,10 +131,9 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 		.dentry = dentry,
 		.authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
 	};
-	char *page, *page2;
-	char *path, *fs_path;
+	char *page = NULL, *page2 = NULL;
 	char *devname;
-	int loc, s;
+	int loc, s, error;
 
 	if (locations == NULL || locations->nlocations <= 0)
 		goto out;
@@ -79,31 +141,25 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 	dprintk("%s: referral at %s/%s\n", __FUNCTION__,
 		dentry->d_parent->d_name.name, dentry->d_name.name);
 
-	/* Ensure fs path is a prefix of current dentry path */
 	page = (char *) __get_free_page(GFP_USER);
-	if (page == NULL)
+	if (!page)
 		goto out;
+
 	page2 = (char *) __get_free_page(GFP_USER);
-	if (page2 == NULL)
+	if (!page2)
 		goto out;
 
-	path = nfs4_path(dentry, page, PAGE_SIZE);
-	if (IS_ERR(path))
-		goto out_free;
-
-	fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
-	if (IS_ERR(fs_path))
-		goto out_free;
-
-	if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
-		dprintk("%s: path %s does not begin with fsroot %s\n", __FUNCTION__, path, fs_path);
-		goto out_free;
+	/* Ensure fs path is a prefix of current dentry path */
+	error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
+	if (error < 0) {
+		mnt = ERR_PTR(error);
+		goto out;
 	}
 
 	devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
 	if (IS_ERR(devname)) {
 		mnt = (struct vfsmount *)devname;
-		goto out_free;
+		goto out;
 	}
 
 	loc = 0;
@@ -140,7 +196,7 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 			addr.sin_port = htons(NFS_PORT);
 			mountdata.addr = &addr;
 
-			mnt = vfs_kern_mount(&nfs_referral_nfs4_fs_type, 0, devname, &mountdata);
+			mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, devname, &mountdata);
 			if (!IS_ERR(mnt)) {
 				break;
 			}
@@ -149,10 +205,9 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 		loc++;
 	}
 
-out_free:
-	free_page((unsigned long)page);
-	free_page((unsigned long)page2);
 out:
+	free_page((unsigned long) page);
+	free_page((unsigned long) page2);
 	dprintk("%s: done\n", __FUNCTION__);
 	return mnt;
 }
@@ -165,7 +220,7 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
  */
 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
 {
-	struct vfsmount *mnt = ERR_PTR(-ENOENT);
+	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 	struct dentry *parent;
 	struct nfs4_fs_locations *fs_locations = NULL;
 	struct page *page;
@@ -183,11 +238,16 @@ struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentr
 		goto out_free;
 
 	/* Get locations */
+	mnt = ERR_PTR(-ENOENT);
+
 	parent = dget_parent(dentry);
-	dprintk("%s: getting locations for %s/%s\n", __FUNCTION__, parent->d_name.name, dentry->d_name.name);
+	dprintk("%s: getting locations for %s/%s\n",
+		__FUNCTION__, parent->d_name.name, dentry->d_name.name);
+
 	err = nfs4_proc_fs_locations(parent->d_inode, dentry, fs_locations, page);
 	dput(parent);
-	if (err != 0 || fs_locations->nlocations <= 0 ||
+	if (err != 0 ||
+	    fs_locations->nlocations <= 0 ||
 	    fs_locations->fs_path.ncomponents <= 0)
 		goto out_free;
 

fs/nfs/nfs4proc.c

@@ -1393,70 +1393,19 @@ static int nfs4_lookup_root(struct nfs_server *server, struct nfs_fh *fhandle,
 	return err;
 }
 
+/*
+ * get the file handle for the "/" directory on the server
+ */
 static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
-		struct nfs_fsinfo *info)
+			      struct nfs_fsinfo *info)
 {
-	struct nfs_fattr *	fattr = info->fattr;
-	unsigned char *		p;
-	struct qstr		q;
-	struct nfs4_lookup_arg args = {
-		.dir_fh = fhandle,
-		.name = &q,
-		.bitmask = nfs4_fattr_bitmap,
-	};
-	struct nfs4_lookup_res res = {
-		.server = server,
-		.fattr = fattr,
-		.fh = fhandle,
-	};
-	struct rpc_message msg = {
-		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOOKUP],
-		.rpc_argp = &args,
-		.rpc_resp = &res,
-	};
 	int status;
 
-	/*
-	 * Now we do a separate LOOKUP for each component of the mount path.
-	 * The LOOKUPs are done separately so that we can conveniently
-	 * catch an ERR_WRONGSEC if it occurs along the way...
-	 */
 	status = nfs4_lookup_root(server, fhandle, info);
-	if (status)
-		goto out;
-
-	p = server->mnt_path;
-	for (;;) {
-		struct nfs4_exception exception = { };
-
-		while (*p == '/')
-			p++;
-		if (!*p)
-			break;
-		q.name = p;
-		while (*p && (*p != '/'))
-			p++;
-		q.len = p - q.name;
-
-		do {
-			nfs_fattr_init(fattr);
-			status = nfs4_handle_exception(server,
-					rpc_call_sync(server->client, &msg, 0),
-					&exception);
-		} while (exception.retry);
-		if (status == 0)
-			continue;
-		if (status == -ENOENT) {
-			printk(KERN_NOTICE "NFS: mount path %s does not exist!\n", server->mnt_path);
-			printk(KERN_NOTICE "NFS: suggestion: try mounting '/' instead.\n");
-		}
-		break;
-	}
 	if (status == 0)
 		status = nfs4_server_capabilities(server, fhandle);
 	if (status == 0)
 		status = nfs4_do_fsinfo(server, fhandle, info);
-out:
 	return nfs4_map_errors(status);
 }
 

fs/nfs/nfs4renewd.c

@@ -127,26 +127,13 @@ nfs4_schedule_state_renewal(struct nfs_client *clp)
 void
 nfs4_renewd_prepare_shutdown(struct nfs_server *server)
 {
-	struct nfs_client *clp = server->nfs_client;
-
-	if (!clp)
-		return;
 	flush_scheduled_work();
-	down_write(&clp->cl_sem);
-	if (!list_empty(&server->nfs4_siblings))
-		list_del_init(&server->nfs4_siblings);
-	up_write(&clp->cl_sem);
 }
 
-/* Must be called with clp->cl_sem locked for writes */
 void
 nfs4_kill_renewd(struct nfs_client *clp)
 {
 	down_read(&clp->cl_sem);
-	if (!list_empty(&clp->cl_superblocks)) {
-		up_read(&clp->cl_sem);
-		return;
-	}
 	cancel_delayed_work(&clp->cl_renewd);
 	up_read(&clp->cl_sem);
 	flush_scheduled_work();

fs/nfs/nfs4state.c

@@ -58,24 +58,6 @@ const nfs4_stateid zero_stateid;
 
 static LIST_HEAD(nfs4_clientid_list);
 
-void
-init_nfsv4_state(struct nfs_server *server)
-{
-	server->nfs_client = NULL;
-	INIT_LIST_HEAD(&server->nfs4_siblings);
-}
-
-void
-destroy_nfsv4_state(struct nfs_server *server)
-{
-	kfree(server->mnt_path);
-	server->mnt_path = NULL;
-	if (server->nfs_client) {
-		nfs_put_client(server->nfs_client);
-		server->nfs_client = NULL;
-	}
-}
-
 static int nfs4_init_client(struct nfs_client *clp, struct rpc_cred *cred)
 {
 	int status = nfs4_proc_setclientid(clp, NFS4_CALLBACK,

fs/nfs/read.c

@@ -171,7 +171,7 @@ static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode,
 		rdata->args.offset = page_offset(page) + rdata->args.pgbase;
 
 		dprintk("NFS: nfs_proc_read(%s, (%s/%Ld), %Lu, %u)\n",
-			NFS_SERVER(inode)->hostname,
+			NFS_SERVER(inode)->nfs_client->cl_hostname,
 			inode->i_sb->s_id,
 			(long long)NFS_FILEID(inode),
 			(unsigned long long)rdata->args.pgbase,

fs/nfs/write.c

@@ -1273,7 +1273,7 @@ int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
 		if (time_before(complain, jiffies)) {
 			dprintk("NFS: faulty NFS server %s:"
 				" (committed = %d) != (stable = %d)\n",
-				NFS_SERVER(data->inode)->hostname,
+				NFS_SERVER(data->inode)->nfs_client->cl_hostname,
 				resp->verf->committed, argp->stable);
 			complain = jiffies + 300 * HZ;
 		}

include/linux/nfs_fs_sb.h

@@ -51,7 +51,6 @@ struct nfs_client {
 	unsigned long		cl_lease_time;
 	unsigned long		cl_last_renewal;
 	struct work_struct	cl_renewd;
-	struct work_struct	cl_recoverd;
 
 	struct rpc_wait_queue	cl_rpcwaitq;
 
@@ -74,6 +73,10 @@ struct nfs_client {
  */
 struct nfs_server {
 	struct nfs_client *	nfs_client;	/* shared client and NFS4 state */
+	struct list_head	client_link;	/* List of other nfs_server structs
+						 * that share the same client
+						 */
+	struct list_head	master_link;	/* link in master servers list */
 	struct rpc_clnt *	client;		/* RPC client handle */
 	struct rpc_clnt *	client_acl;	/* ACL RPC client handle */
 	struct nfs_iostats *	io_stats;	/* I/O statistics */
@@ -92,20 +95,13 @@ struct nfs_server {
 	unsigned int		acdirmin;
 	unsigned int		acdirmax;
 	unsigned int		namelen;
-	char *			hostname;	/* remote hostname */
-	struct nfs_fh		fh;
-	struct sockaddr_in	addr;
+
 	struct nfs_fsid		fsid;
+	__u64			maxfilesize;	/* maximum file size */
 	unsigned long		mount_time;	/* when this fs was mounted */
+	dev_t			s_dev;		/* superblock dev numbers */
+
 #ifdef CONFIG_NFS_V4
-	/* Our own IP address, as a null-terminated string.
-	 * This is used to generate the clientid, and the callback address.
-	 */
-	char			ip_addr[16];
-	char *			mnt_path;
-	struct list_head	nfs4_siblings;	/* List of other nfs_server structs
-						 * that share the same clientid
-						 */
 	u32			attr_bitmask[2];/* V4 bitmask representing the set
 						   of attributes supported on this
 						   filesystem */
@@ -113,6 +109,7 @@ struct nfs_server {
 						   that are supported on this
 						   filesystem */
 #endif
+	void (*destroy)(struct nfs_server *);
 };
 
 /* Server capabilities */