1 files changed, 234 insertions, 64 deletions

diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 8ca44b7b25c..b5a0afc3ee1 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -2,31 +2,131 @@
  * linux/fs/nfs/namespace.c
  *
  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
+ * - Modified by David Howells <dhowells@redhat.com>
  *
  * NFS namespace
  */
 
-#include <linux/config.h>
-
+#include <linux/module.h>
 #include <linux/dcache.h>
+#include <linux/gfp.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/nfs_fs.h>
 #include <linux/string.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/vfs.h>
+#include <linux/sunrpc/gss_api.h>
+#include "internal.h"
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
-LIST_HEAD(nfs_automount_list);
-static void nfs_expire_automounts(void *list);
-static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
+static void nfs_expire_automounts(struct work_struct *work);
+
+static LIST_HEAD(nfs_automount_list);
+static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
 int nfs_mountpoint_expiry_timeout = 500 * HZ;
 
 /*
- * nfs_follow_mountpoint - handle crossing a mountpoint on the server
- * @dentry - dentry of mountpoint
- * @nd - nameidata info
+ * nfs_path - reconstruct the path given an arbitrary dentry
+ * @base - used to return pointer to the end of devname part of path
+ * @dentry - pointer to dentry
+ * @buffer - result buffer
+ * @buflen - length of buffer
+ * @flags - options (see below)
+ *
+ * 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
+ * and in generating /proc/mounts and friends.
+ *
+ * Supported flags:
+ * NFS_PATH_CANONICAL: ensure there is exactly one slash after
+ *		       the original device (export) name
+ *		       (if unset, the original name is returned verbatim)
+ */
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
+	       unsigned flags)
+{
+	char *end;
+	int namelen;
+	unsigned seq;
+	const char *base;
+
+rename_retry:
+	end = buffer+buflen;
+	*--end = '\0';
+	buflen--;
+
+	seq = read_seqbegin(&rename_lock);
+	rcu_read_lock();
+	while (1) {
+		spin_lock(&dentry->d_lock);
+		if (IS_ROOT(dentry))
+			break;
+		namelen = dentry->d_name.len;
+		buflen -= namelen + 1;
+		if (buflen < 0)
+			goto Elong_unlock;
+		end -= namelen;
+		memcpy(end, dentry->d_name.name, namelen);
+		*--end = '/';
+		spin_unlock(&dentry->d_lock);
+		dentry = dentry->d_parent;
+	}
+	if (read_seqretry(&rename_lock, seq)) {
+		spin_unlock(&dentry->d_lock);
+		rcu_read_unlock();
+		goto rename_retry;
+	}
+	if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
+		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);
+	if (flags & NFS_PATH_CANONICAL) {
+		/* Strip off excess slashes in base string */
+		while (namelen > 0 && base[namelen - 1] == '/')
+			namelen--;
+	}
+	buflen -= namelen;
+	if (buflen < 0) {
+		spin_unlock(&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_unlock(&dentry->d_lock);
+	rcu_read_unlock();
+	if (read_seqretry(&rename_lock, seq))
+		goto rename_retry;
+Elong:
+	return ERR_PTR(-ENAMETOOLONG);
+}
+EXPORT_SYMBOL_GPL(nfs_path);
+
+/*
+ * nfs_d_automount - Handle crossing a mountpoint on the server
+ * @path - The mountpoint
  *
  * When we encounter a mountpoint on the server, we want to set up
  * a mountpoint on the client too, to prevent inode numbers from
@@ -36,74 +136,77 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * situation, and that different filesystems may want to use
  * different security flavours.
  */
-static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
+struct vfsmount *nfs_d_automount(struct path *path)
 {
 	struct vfsmount *mnt;
-	struct nfs_server *server = NFS_SERVER(dentry->d_inode);
-	struct dentry *parent;
-	struct nfs_fh fh;
-	struct nfs_fattr fattr;
-	int err;
+	struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
+	struct nfs_fh *fh = NULL;
+	struct nfs_fattr *fattr = NULL;
 
-	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->rpc_ops->lookup(parent->d_inode, &nd->dentry->d_name, &fh, &fattr);
-	dput(parent);
-	if (err != 0)
-		goto out_err;
+	dprintk("--> nfs_d_automount()\n");
 
-	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);
+	mnt = ERR_PTR(-ESTALE);
+	if (IS_ROOT(path->dentry))
+		goto out_nofree;
+
+	mnt = ERR_PTR(-ENOMEM);
+	fh = nfs_alloc_fhandle();
+	fattr = nfs_alloc_fattr();
+	if (fh == NULL || fattr == NULL)
+		goto out;
+
+	dprintk("%s: enter\n", __func__);
+
+	mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
 	if (IS_ERR(mnt))
-		goto out_err;
-
-	mntget(mnt);
-	err = do_add_mount(mnt, nd, nd->mnt->mnt_flags|MNT_SHRINKABLE, &nfs_automount_list);
-	if (err < 0) {
-		mntput(mnt);
-		if (err == -EBUSY)
-			goto out_follow;
-		goto out_err;
-	}
-	mntput(nd->mnt);
-	dput(nd->dentry);
-	nd->mnt = mnt;
-	nd->dentry = dget(mnt->mnt_root);
+		goto out;
+
+	dprintk("%s: done, success\n", __func__);
+	mntget(mnt); /* prevent immediate expiration */
+	mnt_set_expiry(mnt, &nfs_automount_list);
 	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+
 out:
-	dprintk("%s: done, returned %d\n", __FUNCTION__, err);
-	return ERR_PTR(err);
-out_err:
-	path_release(nd);
-	goto out;
-out_follow:
-	while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
-		;
-	err = 0;
-	goto out;
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fh);
+out_nofree:
+	if (IS_ERR(mnt))
+		dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
+	else
+		dprintk("<-- %s() = %p\n", __func__, mnt);
+	return mnt;
 }
 
-struct inode_operations nfs_mountpoint_inode_operations = {
-	.follow_link	= nfs_follow_mountpoint,
+static int
+nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+	if (NFS_FH(dentry->d_inode)->size != 0)
+		return nfs_getattr(mnt, dentry, stat);
+	generic_fillattr(dentry->d_inode, stat);
+	return 0;
+}
+
+static int
+nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	if (NFS_FH(dentry->d_inode)->size != 0)
+		return nfs_setattr(dentry, attr);
+	return -EACCES;
+}
+
+const struct inode_operations nfs_mountpoint_inode_operations = {
 	.getattr	= nfs_getattr,
+	.setattr	= nfs_setattr,
 };
 
-struct inode_operations nfs_referral_inode_operations = {
-	.follow_link	= nfs_follow_mountpoint,
+const struct inode_operations nfs_referral_inode_operations = {
+	.getattr	= nfs_namespace_getattr,
+	.setattr	= nfs_namespace_setattr,
 };
 
-static void nfs_expire_automounts(void *data)
+static void nfs_expire_automounts(struct work_struct *work)
 {
-	struct list_head *list = (struct list_head *)data;
+	struct list_head *list = &nfs_automount_list;
 
 	mark_mounts_for_expiry(list);
 	if (!list_empty(list))
@@ -112,8 +215,75 @@ static void nfs_expire_automounts(void *data)
 
 void nfs_release_automount_timer(void)
 {
-	if (list_empty(&nfs_automount_list)) {
+	if (list_empty(&nfs_automount_list))
 		cancel_delayed_work(&nfs_automount_task);
-		flush_scheduled_work();
-	}
 }
+
+/*
+ * Clone a mountpoint of the appropriate type
+ */
+static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
+					   const char *devname,
+					   struct nfs_clone_mount *mountdata)
+{
+	return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
+}
+
+/**
+ * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
+ * @dentry - parent directory
+ * @fh - filehandle for new root dentry
+ * @fattr - attributes for new root inode
+ * @authflavor - security flavor to use when performing the mount
+ *
+ */
+struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
+				 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
+{
+	struct nfs_clone_mount mountdata = {
+		.sb = dentry->d_sb,
+		.dentry = dentry,
+		.fh = fh,
+		.fattr = fattr,
+		.authflavor = authflavor,
+	};
+	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
+	char *page = (char *) __get_free_page(GFP_USER);
+	char *devname;
+
+	dprintk("--> nfs_do_submount()\n");
+
+	dprintk("%s: submounting on %pd2\n", __func__,
+			dentry);
+	if (page == NULL)
+		goto out;
+	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(dentry->d_sb), devname, &mountdata);
+free_page:
+	free_page((unsigned long)page);
+out:
+	dprintk("%s: done\n", __func__);
+
+	dprintk("<-- nfs_do_submount() = %p\n", mnt);
+	return mnt;
+}
+EXPORT_SYMBOL_GPL(nfs_do_submount);
+
+struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
+			      struct nfs_fh *fh, struct nfs_fattr *fattr)
+{
+	int err;
+	struct dentry *parent = dget_parent(dentry);
+
+	/* Look it up again to get its attributes */
+	err = server->nfs_client->rpc_ops->lookup(parent->d_inode, &dentry->d_name, fh, fattr, NULL);
+	dput(parent);
+	if (err != 0)
+		return ERR_PTR(err);
+
+	return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
+}
+EXPORT_SYMBOL_GPL(nfs_submount);