1 files changed, 251 insertions, 0 deletions

diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
new file mode 100644
index 000000000000..60408646176b
--- /dev/null
+++ b/fs/nfs/namespace.c
@@ -0,0 +1,251 @@
+/*
+ * 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/dcache.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 "internal.h"
+
+#define NFSDBG_FACILITY         NFSDBG_VFS
+
+static void nfs_expire_automounts(void *list);
+
+LIST_HEAD(nfs_automount_list);
+static DECLARE_WORK(nfs_automount_task, nfs_expire_automounts, &nfs_automount_list);
+int nfs_mountpoint_expiry_timeout = 500 * HZ;
+
+static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
+                                        const 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
+ * @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.
+ *
+ * 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 *droot,
+               const struct dentry *dentry,
+               char *buffer, ssize_t buflen)
+{
+        char *end = buffer+buflen;
+        int namelen;
+
+        *--end = '\0';
+        buflen--;
+        spin_lock(&dcache_lock);
+        while (!IS_ROOT(dentry) && dentry != droot) {
+                namelen = dentry->d_name.len;
+                buflen -= namelen + 1;
+                if (buflen < 0)
+                        goto Elong_unlock;
+                end -= namelen;
+                memcpy(end, dentry->d_name.name, namelen);
+                *--end = '/';
+                dentry = dentry->d_parent;
+        }
+        spin_unlock(&dcache_lock);
+        namelen = strlen(base);
+        /* Strip off excess slashes in base string */
+        while (namelen > 0 && base[namelen - 1] == '/')
+                namelen--;
+        buflen -= namelen;
+        if (buflen < 0)
+                goto Elong;
+        end -= namelen;
+        memcpy(end, base, namelen);
+        return end;
+Elong_unlock:
+        spin_unlock(&dcache_lock);
+Elong:
+        return ERR_PTR(-ENAMETOOLONG);
+}
+
+/*
+ * nfs_follow_mountpoint - handle crossing a mountpoint on the server
+ * @dentry - dentry of mountpoint
+ * @nd - nameidata info
+ *
+ * When we encounter a mountpoint on the server, we want to set up
+ * a mountpoint on the client too, to prevent inode numbers from
+ * colliding, and to allow "df" to work properly.
+ * On NFSv4, we also want to allow for the fact that different
+ * filesystems may be migrated to different servers in a failover
+ * 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 *mnt;
+        struct nfs_server *server = NFS_SERVER(dentry->d_inode);
+        struct dentry *parent;
+        struct nfs_fh fh;
+        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);
+
+        /* Look it up again */
+        parent = dget_parent(nd->dentry);
+        err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
+                                                  &nd->dentry->d_name,
+                                                  &fh, &fattr);
+        dput(parent);
+        if (err != 0)
+                goto out_err;
+
+        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;
+
+        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);
+        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);
+        goto out;
+out_follow:
+        while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
+                ;
+        err = 0;
+        goto out;
+}
+
+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)
+{
+        struct list_head *list = (struct list_head *)data;
+
+        mark_mounts_for_expiry(list);
+        if (!list_empty(list))
+                schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+}
+
+void nfs_release_automount_timer(void)
+{
+        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)
+{
+#ifdef CONFIG_NFS_V4
+        struct vfsmount *mnt = NULL;
+        switch (server->nfs_client->cl_nfsversion) {
+                case 2:
+                case 3:
+                        mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
+                        break;
+                case 4:
+                        mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
+        }
+        return mnt;
+#else
+        return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
+#endif
+}
+
+/**
+ * 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,
+                                        struct nfs_fh *fh,
+                                        struct nfs_fattr *fattr)
+{
+        struct nfs_clone_mount mountdata = {
+                .sb = mnt_parent->mnt_sb,
+                .dentry = dentry,
+                .fh = fh,
+                .fattr = fattr,
+        };
+        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 %s/%s\n", __FUNCTION__,
+                        dentry->d_parent->d_name.name,
+                        dentry->d_name.name);
+        if (page == NULL)
+                goto out;
+        devname = nfs_devname(mnt_parent, 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);
+free_page:
+        free_page((unsigned long)page);
+out:
+        dprintk("%s: done\n", __FUNCTION__);
+
+        dprintk("<-- nfs_do_submount() = %p\n", mnt);
+        return mnt;
+}