267 lines
6.7 KiB
C
267 lines
6.7 KiB
C
/*
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* linux/fs/nfs/namespace.c
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*
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* Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
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* - Modified by David Howells <dhowells@redhat.com>
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*
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* NFS namespace
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*/
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#include <linux/dcache.h>
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#include <linux/gfp.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/nfs_fs.h>
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#include <linux/string.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/vfs.h>
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#include "internal.h"
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#define NFSDBG_FACILITY NFSDBG_VFS
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static void nfs_expire_automounts(struct work_struct *work);
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static LIST_HEAD(nfs_automount_list);
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static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
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int nfs_mountpoint_expiry_timeout = 500 * HZ;
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static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
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const struct dentry *dentry,
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struct nfs_fh *fh,
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struct nfs_fattr *fattr);
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/*
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* nfs_path - reconstruct the path given an arbitrary dentry
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* @base - arbitrary string to prepend to the path
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* @droot - pointer to root dentry for mountpoint
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* @dentry - pointer to dentry
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* @buffer - result buffer
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* @buflen - length of buffer
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*
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* Helper function for constructing the path from the
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* root dentry to an arbitrary hashed dentry.
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*
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* This is mainly for use in figuring out the path on the
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* server side when automounting on top of an existing partition.
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*/
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char *nfs_path(const char *base,
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const struct dentry *droot,
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const struct dentry *dentry,
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char *buffer, ssize_t buflen)
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{
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char *end = buffer+buflen;
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int namelen;
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*--end = '\0';
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buflen--;
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spin_lock(&dcache_lock);
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while (!IS_ROOT(dentry) && dentry != droot) {
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namelen = dentry->d_name.len;
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buflen -= namelen + 1;
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if (buflen < 0)
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goto Elong_unlock;
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end -= namelen;
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memcpy(end, dentry->d_name.name, namelen);
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*--end = '/';
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dentry = dentry->d_parent;
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}
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spin_unlock(&dcache_lock);
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if (*end != '/') {
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if (--buflen < 0)
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goto Elong;
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*--end = '/';
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}
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namelen = strlen(base);
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/* Strip off excess slashes in base string */
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while (namelen > 0 && base[namelen - 1] == '/')
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namelen--;
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buflen -= namelen;
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if (buflen < 0)
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goto Elong;
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end -= namelen;
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memcpy(end, base, namelen);
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return end;
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Elong_unlock:
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spin_unlock(&dcache_lock);
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Elong:
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return ERR_PTR(-ENAMETOOLONG);
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}
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/*
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* nfs_follow_mountpoint - handle crossing a mountpoint on the server
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* @dentry - dentry of mountpoint
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* @nd - nameidata info
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*
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* When we encounter a mountpoint on the server, we want to set up
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* a mountpoint on the client too, to prevent inode numbers from
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* colliding, and to allow "df" to work properly.
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* On NFSv4, we also want to allow for the fact that different
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* filesystems may be migrated to different servers in a failover
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* situation, and that different filesystems may want to use
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* different security flavours.
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*/
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static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
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{
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struct vfsmount *mnt;
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struct nfs_server *server = NFS_SERVER(dentry->d_inode);
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struct dentry *parent;
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struct nfs_fh *fh = NULL;
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struct nfs_fattr *fattr = NULL;
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int err;
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dprintk("--> nfs_follow_mountpoint()\n");
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err = -ESTALE;
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if (IS_ROOT(dentry))
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goto out_err;
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err = -ENOMEM;
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fh = nfs_alloc_fhandle();
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fattr = nfs_alloc_fattr();
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if (fh == NULL || fattr == NULL)
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goto out_err;
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dprintk("%s: enter\n", __func__);
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dput(nd->path.dentry);
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nd->path.dentry = dget(dentry);
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/* Look it up again */
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parent = dget_parent(nd->path.dentry);
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err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
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&nd->path.dentry->d_name,
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fh, fattr);
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dput(parent);
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if (err != 0)
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goto out_err;
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if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
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mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
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else
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mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
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fattr);
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err = PTR_ERR(mnt);
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if (IS_ERR(mnt))
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goto out_err;
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mntget(mnt);
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err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
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&nfs_automount_list);
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if (err < 0) {
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mntput(mnt);
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if (err == -EBUSY)
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goto out_follow;
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goto out_err;
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}
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path_put(&nd->path);
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nd->path.mnt = mnt;
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nd->path.dentry = dget(mnt->mnt_root);
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schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
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out:
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nfs_free_fattr(fattr);
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nfs_free_fhandle(fh);
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dprintk("%s: done, returned %d\n", __func__, err);
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dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
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return ERR_PTR(err);
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out_err:
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path_put(&nd->path);
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goto out;
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out_follow:
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while (d_mountpoint(nd->path.dentry) &&
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follow_down(&nd->path))
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;
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err = 0;
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goto out;
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}
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const struct inode_operations nfs_mountpoint_inode_operations = {
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.follow_link = nfs_follow_mountpoint,
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.getattr = nfs_getattr,
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};
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const struct inode_operations nfs_referral_inode_operations = {
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.follow_link = nfs_follow_mountpoint,
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};
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static void nfs_expire_automounts(struct work_struct *work)
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{
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struct list_head *list = &nfs_automount_list;
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mark_mounts_for_expiry(list);
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if (!list_empty(list))
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schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
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}
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void nfs_release_automount_timer(void)
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{
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if (list_empty(&nfs_automount_list))
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cancel_delayed_work(&nfs_automount_task);
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}
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/*
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* Clone a mountpoint of the appropriate type
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*/
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static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
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const char *devname,
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struct nfs_clone_mount *mountdata)
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{
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#ifdef CONFIG_NFS_V4
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struct vfsmount *mnt = ERR_PTR(-EINVAL);
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switch (server->nfs_client->rpc_ops->version) {
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case 2:
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case 3:
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mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
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break;
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case 4:
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mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
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}
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return mnt;
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#else
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return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
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#endif
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}
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/**
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* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
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* @mnt_parent - mountpoint of parent directory
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* @dentry - parent directory
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* @fh - filehandle for new root dentry
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* @fattr - attributes for new root inode
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*
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*/
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static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
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const struct dentry *dentry,
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struct nfs_fh *fh,
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struct nfs_fattr *fattr)
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{
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struct nfs_clone_mount mountdata = {
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.sb = mnt_parent->mnt_sb,
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.dentry = dentry,
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.fh = fh,
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.fattr = fattr,
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};
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struct vfsmount *mnt = ERR_PTR(-ENOMEM);
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char *page = (char *) __get_free_page(GFP_USER);
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char *devname;
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dprintk("--> nfs_do_submount()\n");
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dprintk("%s: submounting on %s/%s\n", __func__,
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dentry->d_parent->d_name.name,
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dentry->d_name.name);
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if (page == NULL)
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goto out;
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devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
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mnt = (struct vfsmount *)devname;
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if (IS_ERR(devname))
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goto free_page;
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mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
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free_page:
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free_page((unsigned long)page);
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out:
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dprintk("%s: done\n", __func__);
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dprintk("<-- nfs_do_submount() = %p\n", mnt);
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return mnt;
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}
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