--- /dev/null
+/*
+ * 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/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;
+
+/*
+ * 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
+ *
+ */
+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;
+}
git://git.onelab.eu / linux-2.6.git / blobdiff