Merge branch 'mnt_devname' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'mnt_devname' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  vfs: bury ->get_sb()
  nfs: switch NFS from ->get_sb() to ->mount()
  nfs: stop mangling ->mnt_devname on NFS
  vfs: new superblock methods to override /proc/*/mount{s,info}
  nfs: nfs_do_{ref,sub}mount() superblock argument is redundant
  nfs: make nfs_path() work without vfsmount
  nfs: store devname at disconnected NFS roots
  nfs: propagate devname to nfs{,4}_get_root()

Documentation/filesystems/Locking

@@ -166,13 +166,11 @@ prototypes:
 	void (*kill_sb) (struct super_block *);
 locking rules:
 		may block
-get_sb		yes
 mount		yes
 kill_sb		yes
 
-->get_sb() returns error or 0 with locked superblock attached to the vfsmount
-(exclusive on ->s_umount).
-->mount() returns ERR_PTR or the root dentry.
+->mount() returns ERR_PTR or the root dentry; its superblock should be locked
+on return.
 ->kill_sb() takes a write-locked superblock, does all shutdown work on it,
 unlocks and drops the reference.
 

Documentation/filesystems/porting

@@ -394,3 +394,10 @@ file) you must return -EOPNOTSUPP if FALLOC_FL_PUNCH_HOLE is set in mode.
 Currently you can only have FALLOC_FL_PUNCH_HOLE with FALLOC_FL_KEEP_SIZE set,
 so the i_size should not change when hole punching, even when puching the end of
 a file off.
+
+--
+[mandatory]
+	->get_sb() is gone.  Switch to use of ->mount().  Typically it's just
+a matter of switching from calling get_sb_... to mount_... and changing the
+function type.  If you were doing it manually, just switch from setting ->mnt_root
+to some pointer to returning that pointer.  On errors return ERR_PTR(...).

Documentation/filesystems/vfs.txt

@@ -95,10 +95,11 @@ functions:
    extern int unregister_filesystem(struct file_system_type *);
 
 The passed struct file_system_type describes your filesystem. When a
-request is made to mount a device onto a directory in your filespace,
-the VFS will call the appropriate get_sb() method for the specific
-filesystem. The dentry for the mount point will then be updated to
-point to the root inode for the new filesystem.
+request is made to mount a filesystem onto a directory in your namespace,
+the VFS will call the appropriate mount() method for the specific
+filesystem.  New vfsmount refering to the tree returned by ->mount()
+will be attached to the mountpoint, so that when pathname resolution
+reaches the mountpoint it will jump into the root of that vfsmount.
 
 You can see all filesystems that are registered to the kernel in the
 file /proc/filesystems.
@@ -107,14 +108,14 @@ file /proc/filesystems.
 struct file_system_type
 -----------------------
 
-This describes the filesystem. As of kernel 2.6.22, the following
+This describes the filesystem. As of kernel 2.6.39, the following
 members are defined:
 
 struct file_system_type {
 	const char *name;
 	int fs_flags;
-        int (*get_sb) (struct file_system_type *, int,
-                       const char *, void *, struct vfsmount *);
+        struct dentry (*mount) (struct file_system_type *, int,
+                       const char *, void *);
         void (*kill_sb) (struct super_block *);
         struct module *owner;
         struct file_system_type * next;
@@ -128,11 +129,11 @@ struct file_system_type {
 
   fs_flags: various flags (i.e. FS_REQUIRES_DEV, FS_NO_DCACHE, etc.)
 
-  get_sb: the method to call when a new instance of this
+  mount: the method to call when a new instance of this
 	filesystem should be mounted
 
   kill_sb: the method to call when an instance of this filesystem
-	should be unmounted
+	should be shut down
 
   owner: for internal VFS use: you should initialize this to THIS_MODULE in
   	most cases.
@@ -141,7 +142,7 @@ struct file_system_type {
 
   s_lock_key, s_umount_key: lockdep-specific
 
-The get_sb() method has the following arguments:
+The mount() method has the following arguments:
 
   struct file_system_type *fs_type: describes the filesystem, partly initialized
   	by the specific filesystem code
@@ -153,32 +154,39 @@ The get_sb() method has the following arguments:
   void *data: arbitrary mount options, usually comes as an ASCII
 	string (see "Mount Options" section)
 
-  struct vfsmount *mnt: a vfs-internal representation of a mount point
+The mount() method must return the root dentry of the tree requested by
+caller.  An active reference to its superblock must be grabbed and the
+superblock must be locked.  On failure it should return ERR_PTR(error).
 
-The get_sb() method must determine if the block device specified
-in the dev_name and fs_type contains a filesystem of the type the method
-supports. If it succeeds in opening the named block device, it initializes a
-struct super_block descriptor for the filesystem contained by the block device.
-On failure it returns an error.
+The arguments match those of mount(2) and their interpretation
+depends on filesystem type.  E.g. for block filesystems, dev_name is
+interpreted as block device name, that device is opened and if it
+contains a suitable filesystem image the method creates and initializes
+struct super_block accordingly, returning its root dentry to caller.
+
+->mount() may choose to return a subtree of existing filesystem - it
+doesn't have to create a new one.  The main result from the caller's
+point of view is a reference to dentry at the root of (sub)tree to
+be attached; creation of new superblock is a common side effect.
 
 The most interesting member of the superblock structure that the
-get_sb() method fills in is the "s_op" field. This is a pointer to
+mount() method fills in is the "s_op" field. This is a pointer to
 a "struct super_operations" which describes the next level of the
 filesystem implementation.
 
-Usually, a filesystem uses one of the generic get_sb() implementations
-and provides a fill_super() method instead. The generic methods are:
+Usually, a filesystem uses one of the generic mount() implementations
+and provides a fill_super() callback instead. The generic variants are:
 
-  get_sb_bdev: mount a filesystem residing on a block device
+  mount_bdev: mount a filesystem residing on a block device
 
-  get_sb_nodev: mount a filesystem that is not backed by a device
+  mount_nodev: mount a filesystem that is not backed by a device
 
-  get_sb_single: mount a filesystem which shares the instance between
+  mount_single: mount a filesystem which shares the instance between
   	all mounts
 
-A fill_super() method implementation has the following arguments:
+A fill_super() callback implementation has the following arguments:
 
-  struct super_block *sb: the superblock structure. The method fill_super()
+  struct super_block *sb: the superblock structure. The callback
   	must initialize this properly.
 
   void *data: arbitrary mount options, usually comes as an ASCII

fs/namespace.c

@@ -978,7 +978,13 @@ static int show_vfsmnt(struct seq_file *m, void *v)
 	int err = 0;
 	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 
-	mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (mnt->mnt_sb->s_op->show_devname) {
+		err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+		if (err)
+			goto out;
+	} else {
+		mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	}
 	seq_putc(m, ' ');
 	seq_path(m, &mnt_path, " \t\n\\");
 	seq_putc(m, ' ');
@@ -1025,7 +1031,12 @@ static int show_mountinfo(struct seq_file *m, void *v)
 
 	seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
 		   MAJOR(sb->s_dev), MINOR(sb->s_dev));
-	seq_dentry(m, mnt->mnt_root, " \t\n\\");
+	if (sb->s_op->show_path)
+		err = sb->s_op->show_path(m, mnt);
+	else
+		seq_dentry(m, mnt->mnt_root, " \t\n\\");
+	if (err)
+		goto out;
 	seq_putc(m, ' ');
 	seq_path_root(m, &mnt_path, &root, " \t\n\\");
 	if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
@@ -1060,7 +1071,12 @@ static int show_mountinfo(struct seq_file *m, void *v)
 	seq_puts(m, " - ");
 	show_type(m, sb);
 	seq_putc(m, ' ');
-	mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (sb->s_op->show_devname)
+		err = sb->s_op->show_devname(m, mnt);
+	else
+		mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (err)
+		goto out;
 	seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
 	err = show_sb_opts(m, sb);
 	if (err)
@@ -1086,11 +1102,15 @@ static int show_vfsstat(struct seq_file *m, void *v)
 	int err = 0;
 
 	/* device */
-	if (mnt->mnt_devname) {
-		seq_puts(m, "device ");
-		mangle(m, mnt->mnt_devname);
-	} else
-		seq_puts(m, "no device");
+	if (mnt->mnt_sb->s_op->show_devname) {
+		err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+	} else {
+		if (mnt->mnt_devname) {
+			seq_puts(m, "device ");
+			mangle(m, mnt->mnt_devname);
+		} else
+			seq_puts(m, "no device");
+	}
 
 	/* mount point */
 	seq_puts(m, " mounted on ");
@@ -1104,7 +1124,8 @@ static int show_vfsstat(struct seq_file *m, void *v)
 	/* optional statistics */
 	if (mnt->mnt_sb->s_op->show_stats) {
 		seq_putc(m, ' ');
-		err = mnt->mnt_sb->s_op->show_stats(m, mnt);
+		if (!err)
+			err = mnt->mnt_sb->s_op->show_stats(m, mnt);
 	}
 
 	seq_putc(m, '\n');

fs/nfs/dir.c

@@ -1169,11 +1169,23 @@ static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
 	iput(inode);
 }
 
+static void nfs_d_release(struct dentry *dentry)
+{
+	/* free cached devname value, if it survived that far */
+	if (unlikely(dentry->d_fsdata)) {
+		if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+			WARN_ON(1);
+		else
+			kfree(dentry->d_fsdata);
+	}
+}
+
 const struct dentry_operations nfs_dentry_operations = {
 	.d_revalidate	= nfs_lookup_revalidate,
 	.d_delete	= nfs_dentry_delete,
 	.d_iput		= nfs_dentry_iput,
 	.d_automount	= nfs_d_automount,
+	.d_release	= nfs_d_release,
 };
 
 static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
@@ -1248,6 +1260,7 @@ const struct dentry_operations nfs4_dentry_operations = {
 	.d_delete	= nfs_dentry_delete,
 	.d_iput		= nfs_dentry_iput,
 	.d_automount	= nfs_d_automount,
+	.d_release	= nfs_d_release,
 };
 
 /*

fs/nfs/getroot.c

@@ -75,18 +75,25 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
 /*
  * get an NFS2/NFS3 root dentry from the root filehandle
  */
-struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
+struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
+			    const char *devname)
 {
 	struct nfs_server *server = NFS_SB(sb);
 	struct nfs_fsinfo fsinfo;
 	struct dentry *ret;
 	struct inode *inode;
+	void *name = kstrdup(devname, GFP_KERNEL);
 	int error;
 
+	if (!name)
+		return ERR_PTR(-ENOMEM);
+
 	/* get the actual root for this mount */
 	fsinfo.fattr = nfs_alloc_fattr();
-	if (fsinfo.fattr == NULL)
+	if (fsinfo.fattr == NULL) {
+		kfree(name);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
 	if (error < 0) {
@@ -119,7 +126,15 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
 	}
 
 	security_d_instantiate(ret, inode);
+	spin_lock(&ret->d_lock);
+	if (IS_ROOT(ret) && !(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
+		ret->d_fsdata = name;
+		name = NULL;
+	}
+	spin_unlock(&ret->d_lock);
 out:
+	if (name)
+		kfree(name);
 	nfs_free_fattr(fsinfo.fattr);
 	return ret;
 }
@@ -169,27 +184,35 @@ int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
 /*
  * get an NFS4 root dentry from the root filehandle
  */
-struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
+struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh,
+			     const char *devname)
 {
 	struct nfs_server *server = NFS_SB(sb);
 	struct nfs_fattr *fattr = NULL;
 	struct dentry *ret;
 	struct inode *inode;
+	void *name = kstrdup(devname, GFP_KERNEL);
 	int error;
 
 	dprintk("--> nfs4_get_root()\n");
 
+	if (!name)
+		return ERR_PTR(-ENOMEM);
+
 	/* 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);
+		kfree(name);
 		return ERR_PTR(error);
 	}
 
 	fattr = nfs_alloc_fattr();
-	if (fattr == NULL)
-		return ERR_PTR(-ENOMEM);;
+	if (fattr == NULL) {
+		kfree(name);
+		return ERR_PTR(-ENOMEM);
+	}
 
 	/* get the actual root for this mount */
 	error = server->nfs_client->rpc_ops->getattr(server, mntfh, fattr);
@@ -223,8 +246,15 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
 	}
 
 	security_d_instantiate(ret, inode);
-
+	spin_lock(&ret->d_lock);
+	if (IS_ROOT(ret) && !(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
+		ret->d_fsdata = name;
+		name = NULL;
+	}
+	spin_unlock(&ret->d_lock);
 out:
+	if (name)
+		kfree(name);
 	nfs_free_fattr(fattr);
 	dprintk("<-- nfs4_get_root()\n");
 	return ret;

fs/nfs/internal.h

@@ -163,10 +163,10 @@ static inline void nfs_fs_proc_exit(void)
 
 /* nfs4namespace.c */
 #ifdef CONFIG_NFS_V4
-extern struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry);
+extern struct vfsmount *nfs_do_refmount(struct dentry *dentry);
 #else
 static inline
-struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
+struct vfsmount *nfs_do_refmount(struct dentry *dentry)
 {
 	return ERR_PTR(-ENOENT);
 }
@@ -247,16 +247,16 @@ extern void nfs_sb_active(struct super_block *sb);
 extern void nfs_sb_deactive(struct super_block *sb);
 
 /* namespace.c */
-extern char *nfs_path(const char *base,
-		      const struct dentry *droot,
-		      const struct dentry *dentry,
+extern char *nfs_path(char **p, struct dentry *dentry,
 		      char *buffer, ssize_t buflen);
 extern struct vfsmount *nfs_d_automount(struct path *path);
 
 /* getroot.c */
-extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *);
+extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *,
+				   const char *);
 #ifdef CONFIG_NFS_V4
-extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *);
+extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *,
+				    const char *);
 
 extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh);
 #endif
@@ -288,12 +288,11 @@ extern int _nfs4_call_sync_session(struct nfs_server *server,
 /*
  * Determine the device name as a string
  */
-static inline char *nfs_devname(const struct vfsmount *mnt_parent,
-				const struct dentry *dentry,
+static inline char *nfs_devname(struct dentry *dentry,
 				char *buffer, ssize_t buflen)
 {
-	return nfs_path(mnt_parent->mnt_devname, mnt_parent->mnt_root,
-			dentry, buffer, buflen);
+	char *dummy;
+	return nfs_path(&dummy, dentry, buffer, buflen);
 }
 
 /*

fs/nfs/namespace.c

@@ -25,33 +25,30 @@ static LIST_HEAD(nfs_automount_list);
 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
 int nfs_mountpoint_expiry_timeout = 500 * HZ;
 
-static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
-					const struct dentry *dentry,
+static struct vfsmount *nfs_do_submount(struct dentry *dentry,
 					struct nfs_fh *fh,
 					struct nfs_fattr *fattr);
 
 /*
  * nfs_path - reconstruct the path given an arbitrary dentry
- * @base - arbitrary string to prepend to the path
- * @droot - pointer to root dentry for mountpoint
+ * @base - used to return pointer to the end of devname part of path
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
  *
- * Helper function for constructing the path from the
- * root dentry to an arbitrary hashed dentry.
+ * Helper function for constructing the server pathname
+ * by arbitrary hashed dentry.
  *
  * This is mainly for use in figuring out the path on the
- * server side when automounting on top of an existing partition.
+ * server side when automounting on top of an existing partition
+ * and in generating /proc/mounts and friends.
  */
-char *nfs_path(const char *base,
-	       const struct dentry *droot,
-	       const struct dentry *dentry,
-	       char *buffer, ssize_t buflen)
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
 {
 	char *end;
 	int namelen;
 	unsigned seq;
+	const char *base;
 
 rename_retry:
 	end = buffer+buflen;
@@ -60,7 +57,10 @@ char *nfs_path(const char *base,
 
 	seq = read_seqbegin(&rename_lock);
 	rcu_read_lock();
-	while (!IS_ROOT(dentry) && dentry != droot) {
+	while (1) {
+		spin_lock(&dentry->d_lock);
+		if (IS_ROOT(dentry))
+			break;
 		namelen = dentry->d_name.len;
 		buflen -= namelen + 1;
 		if (buflen < 0)
@@ -68,27 +68,47 @@ char *nfs_path(const char *base,
 		end -= namelen;
 		memcpy(end, dentry->d_name.name, namelen);
 		*--end = '/';
+		spin_unlock(&dentry->d_lock);
 		dentry = dentry->d_parent;
 	}
-	rcu_read_unlock();
-	if (read_seqretry(&rename_lock, seq))
+	if (read_seqretry(&rename_lock, seq)) {
+		spin_unlock(&dentry->d_lock);
+		rcu_read_unlock();
 		goto rename_retry;
+	}
 	if (*end != '/') {
-		if (--buflen < 0)
+		if (--buflen < 0) {
+			spin_unlock(&dentry->d_lock);
+			rcu_read_unlock();
 			goto Elong;
+		}
 		*--end = '/';
 	}
+	*p = end;
+	base = dentry->d_fsdata;
+	if (!base) {
+		spin_unlock(&dentry->d_lock);
+		rcu_read_unlock();
+		WARN_ON(1);
+		return end;
+	}
 	namelen = strlen(base);
 	/* Strip off excess slashes in base string */
 	while (namelen > 0 && base[namelen - 1] == '/')
 		namelen--;
 	buflen -= namelen;
-	if (buflen < 0)
+	if (buflen < 0) {
+		spin_lock(&dentry->d_lock);
+		rcu_read_unlock();
 		goto Elong;
+	}
 	end -= namelen;
 	memcpy(end, base, namelen);
+	spin_unlock(&dentry->d_lock);
+	rcu_read_unlock();
 	return end;
 Elong_unlock:
+	spin_lock(&dentry->d_lock);
 	rcu_read_unlock();
 	if (read_seqretry(&rename_lock, seq))
 		goto rename_retry;
@@ -143,9 +163,9 @@ struct vfsmount *nfs_d_automount(struct path *path)
 	}
 
 	if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
-		mnt = nfs_do_refmount(path->mnt, path->dentry);
+		mnt = nfs_do_refmount(path->dentry);
 	else
-		mnt = nfs_do_submount(path->mnt, path->dentry, fh, fattr);
+		mnt = nfs_do_submount(path->dentry, fh, fattr);
 	if (IS_ERR(mnt))
 		goto out;
 
@@ -209,19 +229,17 @@ static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
 
 /**
  * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
- * @mnt_parent - mountpoint of parent directory
  * @dentry - parent directory
  * @fh - filehandle for new root dentry
  * @fattr - attributes for new root inode
  *
  */
-static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
-					const struct dentry *dentry,
+static struct vfsmount *nfs_do_submount(struct dentry *dentry,
 					struct nfs_fh *fh,
 					struct nfs_fattr *fattr)
 {
 	struct nfs_clone_mount mountdata = {
-		.sb = mnt_parent->mnt_sb,
+		.sb = dentry->d_sb,
 		.dentry = dentry,
 		.fh = fh,
 		.fattr = fattr,
@@ -237,11 +255,11 @@ static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
 			dentry->d_name.name);
 	if (page == NULL)
 		goto out;
-	devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
+	devname = nfs_devname(dentry, page, PAGE_SIZE);
 	mnt = (struct vfsmount *)devname;
 	if (IS_ERR(devname))
 		goto free_page;
-	mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
+	mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
 free_page:
 	free_page((unsigned long)page);
 out:

fs/nfs/nfs4namespace.c

@@ -54,33 +54,29 @@ static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
 /*
  * 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)
+static char *nfs4_path(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);
+	char *limit;
+	char *path = nfs_path(&limit, dentry, buffer, buflen);
+	if (!IS_ERR(path)) {
+		char *colon = strchr(path, ':');
+		if (colon && colon < limit)
+			path = colon + 1;
+	}
+	return path;
 }
 
 /*
  * 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,
+static int nfs4_validate_fspath(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);
+	path = nfs4_path(dentry, page, PAGE_SIZE);
 	if (IS_ERR(path))
 		return PTR_ERR(path);
 
@@ -165,20 +161,18 @@ static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 
 /**
  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
- * @mnt_parent - mountpoint of parent directory
  * @dentry - parent directory
  * @locations - array of NFSv4 server location information
  *
  */
-static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
-					    const struct dentry *dentry,
+static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 					    const struct nfs4_fs_locations *locations)
 {
 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
 	struct nfs_clone_mount mountdata = {
-		.sb = mnt_parent->mnt_sb,
+		.sb = dentry->d_sb,
 		.dentry = dentry,
-		.authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
+		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 	};
 	char *page = NULL, *page2 = NULL;
 	int loc, error;
@@ -198,7 +192,7 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 		goto out;
 
 	/* Ensure fs path is a prefix of current dentry path */
-	error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
+	error = nfs4_validate_fspath(dentry, locations, page, page2);
 	if (error < 0) {
 		mnt = ERR_PTR(error);
 		goto out;
@@ -225,11 +219,10 @@ static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
 
 /*
  * nfs_do_refmount - handle crossing a referral on server
- * @mnt_parent - mountpoint of referral
  * @dentry - dentry of referral
  *
  */
-struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
+struct vfsmount *nfs_do_refmount(struct dentry *dentry)
 {
 	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 	struct dentry *parent;
@@ -262,7 +255,7 @@ struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentr
 	    fs_locations->fs_path.ncomponents <= 0)
 		goto out_free;
 
-	mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
+	mnt = nfs_follow_referral(dentry, fs_locations);
 out_free:
 	__free_page(page);
 	kfree(fs_locations);

fs/nfs/unlink.c

@@ -148,6 +148,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
 	alias = d_lookup(parent, &data->args.name);
 	if (alias != NULL) {
 		int ret = 0;
+		void *devname_garbage = NULL;
 
 		/*
 		 * Hey, we raced with lookup... See if we need to transfer
@@ -157,6 +158,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
 		spin_lock(&alias->d_lock);
 		if (alias->d_inode != NULL &&
 		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
+			devname_garbage = alias->d_fsdata;
 			alias->d_fsdata = data;
 			alias->d_flags |= DCACHE_NFSFS_RENAMED;
 			ret = 1;
@@ -164,6 +166,13 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
 		spin_unlock(&alias->d_lock);
 		nfs_dec_sillycount(dir);
 		dput(alias);
+		/*
+		 * If we'd displaced old cached devname, free it.  At that
+		 * point dentry is definitely not a root, so we won't need
+		 * that anymore.
+		 */
+		if (devname_garbage)
+			kfree(devname_garbage);
 		return ret;
 	}
 	data->dir = igrab(dir);
@@ -252,6 +261,7 @@ nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct nfs_unlinkdata *data;
 	int status = -ENOMEM;
+	void *devname_garbage = NULL;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (data == NULL)
@@ -269,8 +279,16 @@ nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 		goto out_unlock;
 	dentry->d_flags |= DCACHE_NFSFS_RENAMED;
+	devname_garbage = dentry->d_fsdata;
 	dentry->d_fsdata = data;
 	spin_unlock(&dentry->d_lock);
+	/*
+	 * If we'd displaced old cached devname, free it.  At that
+	 * point dentry is definitely not a root, so we won't need
+	 * that anymore.
+	 */
+	if (devname_garbage)
+		kfree(devname_garbage);
 	return 0;
 out_unlock:
 	spin_unlock(&dentry->d_lock);
@@ -299,6 +317,7 @@ nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 		data = dentry->d_fsdata;
+		dentry->d_fsdata = NULL;
 	}
 	spin_unlock(&dentry->d_lock);
 
@@ -315,6 +334,7 @@ nfs_cancel_async_unlink(struct dentry *dentry)
 		struct nfs_unlinkdata *data = dentry->d_fsdata;
 
 		dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
+		dentry->d_fsdata = NULL;
 		spin_unlock(&dentry->d_lock);
 		nfs_free_unlinkdata(data);
 		return;

fs/super.c

@@ -843,23 +843,6 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
 }
 EXPORT_SYMBOL(mount_bdev);
 
-int get_sb_bdev(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt)
-{
-	struct dentry *root;
-
-	root = mount_bdev(fs_type, flags, dev_name, data, fill_super);
-	if (IS_ERR(root))
-		return PTR_ERR(root);
-	mnt->mnt_root = root;
-	mnt->mnt_sb = root->d_sb;
-	return 0;
-}
-
-EXPORT_SYMBOL(get_sb_bdev);
-
 void kill_block_super(struct super_block *sb)
 {
 	struct block_device *bdev = sb->s_bdev;
@@ -897,22 +880,6 @@ struct dentry *mount_nodev(struct file_system_type *fs_type,
 }
 EXPORT_SYMBOL(mount_nodev);
 
-int get_sb_nodev(struct file_system_type *fs_type,
-	int flags, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt)
-{
-	struct dentry *root;
-
-	root = mount_nodev(fs_type, flags, data, fill_super);
-	if (IS_ERR(root))
-		return PTR_ERR(root);
-	mnt->mnt_root = root;
-	mnt->mnt_sb = root->d_sb;
-	return 0;
-}
-EXPORT_SYMBOL(get_sb_nodev);
-
 static int compare_single(struct super_block *s, void *p)
 {
 	return 1;
@@ -943,22 +910,6 @@ struct dentry *mount_single(struct file_system_type *fs_type,
 }
 EXPORT_SYMBOL(mount_single);
 
-int get_sb_single(struct file_system_type *fs_type,
-	int flags, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt)
-{
-	struct dentry *root;
-	root = mount_single(fs_type, flags, data, fill_super);
-	if (IS_ERR(root))
-		return PTR_ERR(root);
-	mnt->mnt_root = root;
-	mnt->mnt_sb = root->d_sb;
-	return 0;
-}
-
-EXPORT_SYMBOL(get_sb_single);
-
 struct vfsmount *
 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
 {
@@ -988,19 +939,13 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
 			goto out_free_secdata;
 	}
 
-	if (type->mount) {
-		root = type->mount(type, flags, name, data);
-		if (IS_ERR(root)) {
-			error = PTR_ERR(root);
-			goto out_free_secdata;
-		}
-		mnt->mnt_root = root;
-		mnt->mnt_sb = root->d_sb;
-	} else {
-		error = type->get_sb(type, flags, name, data, mnt);
-		if (error < 0)
-			goto out_free_secdata;
+	root = type->mount(type, flags, name, data);
+	if (IS_ERR(root)) {
+		error = PTR_ERR(root);
+		goto out_free_secdata;
 	}
+	mnt->mnt_root = root;
+	mnt->mnt_sb = root->d_sb;
 	BUG_ON(!mnt->mnt_sb);
 	WARN_ON(!mnt->mnt_sb->s_bdi);
 	mnt->mnt_sb->s_flags |= MS_BORN;

include/linux/fs.h

@@ -1631,6 +1631,8 @@ struct super_operations {
 	void (*umount_begin) (struct super_block *);
 
 	int (*show_options)(struct seq_file *, struct vfsmount *);
+	int (*show_devname)(struct seq_file *, struct vfsmount *);
+	int (*show_path)(struct seq_file *, struct vfsmount *);
 	int (*show_stats)(struct seq_file *, struct vfsmount *);
 #ifdef CONFIG_QUOTA
 	ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
@@ -1794,8 +1796,6 @@ int sync_inode_metadata(struct inode *inode, int wait);
 struct file_system_type {
 	const char *name;
 	int fs_flags;
-	int (*get_sb) (struct file_system_type *, int,
-		       const char *, void *, struct vfsmount *);
 	struct dentry *(*mount) (struct file_system_type *, int,
 		       const char *, void *);
 	void (*kill_sb) (struct super_block *);
@@ -1818,24 +1818,12 @@ extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
 extern struct dentry *mount_bdev(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data,
 	int (*fill_super)(struct super_block *, void *, int));
-extern int get_sb_bdev(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt);
 extern struct dentry *mount_single(struct file_system_type *fs_type,
 	int flags, void *data,
 	int (*fill_super)(struct super_block *, void *, int));
-extern int get_sb_single(struct file_system_type *fs_type,
-	int flags, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt);
 extern struct dentry *mount_nodev(struct file_system_type *fs_type,
 	int flags, void *data,
 	int (*fill_super)(struct super_block *, void *, int));
-extern int get_sb_nodev(struct file_system_type *fs_type,
-	int flags, void *data,
-	int (*fill_super)(struct super_block *, void *, int),
-	struct vfsmount *mnt);
 void generic_shutdown_super(struct super_block *sb);
 void kill_block_super(struct super_block *sb);
 void kill_anon_super(struct super_block *sb);