kernel-ark/fs/nfs/namespace.c
Arjan van de Ven 92e1d5be91 [PATCH] mark struct inode_operations const 2
Many struct inode_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:46 -08:00

250 lines
6.4 KiB
C

/*
* 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(struct work_struct *work);
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,
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;
}
const struct inode_operations nfs_mountpoint_inode_operations = {
.follow_link = nfs_follow_mountpoint,
.getattr = nfs_getattr,
};
const struct inode_operations nfs_referral_inode_operations = {
.follow_link = nfs_follow_mountpoint,
};
static void nfs_expire_automounts(struct work_struct *work)
{
struct list_head *list = &nfs_automount_list;
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;
}