[linux.git] / fs / nfs / namespace.c

/*
 * linux/fs/nfs/namespace.c
 *
 * Copyright (C) 2005 Trond Myklebust <[email protected]>
 * - Modified by David Howells <[email protected]>
 *
 * NFS namespace
 */

#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 "internal.h"

#define NFSDBG_FACILITY		NFSDBG_VFS

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;

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);
	if (*end != '/') {
		if (--buflen < 0)
			goto Elong;
		*--end = '/';
	}
	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 = NULL;
	struct nfs_fattr *fattr = NULL;
	int err;

	dprintk("--> nfs_follow_mountpoint()\n");

	err = -ESTALE;
	if (IS_ROOT(dentry))
		goto out_err;

	err = -ENOMEM;
	fh = nfs_alloc_fhandle();
	fattr = nfs_alloc_fattr();
	if (fh == NULL || fattr == NULL)
		goto out_err;

	dprintk("%s: enter\n", __func__);
	dput(nd->path.dentry);
	nd->path.dentry = dget(dentry);

	/* Look it up again */
	parent = dget_parent(nd->path.dentry);
	err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
						  &nd->path.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->path.mnt, nd->path.dentry);
	else
		mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
				      fattr);
	err = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out_err;

	mntget(mnt);
	err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
			   &nfs_automount_list);
	if (err < 0) {
		mntput(mnt);
		if (err == -EBUSY)
			goto out_follow;
		goto out_err;
	}
	path_put(&nd->path);
	nd->path.mnt = mnt;
	nd->path.dentry = dget(mnt->mnt_root);
	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
out:
	nfs_free_fattr(fattr);
	nfs_free_fhandle(fh);
	dprintk("%s: done, returned %d\n", __func__, err);

	dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
	return ERR_PTR(err);
out_err:
	path_put(&nd->path);
	goto out;
out_follow:
	while (d_mountpoint(nd->path.dentry) &&
	       follow_down(&nd->path))
		;
	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);
}

/*
 * 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 = ERR_PTR(-EINVAL);
	switch (server->nfs_client->rpc_ops->version) {
		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", __func__,
			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", __func__);

	dprintk("<-- nfs_do_submount() = %p\n", mnt);
	return mnt;
}
Commit	Line	Data
55a97593 TM	1	/*
	2	* linux/fs/nfs/namespace.c
	3	*
	4	* Copyright (C) 2005 Trond Myklebust <[email protected]>
54ceac45	5	* - Modified by David Howells <[email protected]>
55a97593 TM	6	*
	7	* NFS namespace
	8	*/
	9
55a97593	10	#include <linux/dcache.h>
5a0e3ad6	11	#include <linux/gfp.h>
55a97593 TM	12	#include <linux/mount.h>
	13	#include <linux/namei.h>
	14	#include <linux/nfs_fs.h>
	15	#include <linux/string.h>
	16	#include <linux/sunrpc/clnt.h>
	17	#include <linux/vfs.h>
f7b422b1	18	#include "internal.h"
55a97593 TM	19
	20	#define NFSDBG_FACILITY NFSDBG_VFS
	21
65f27f38	22	static void nfs_expire_automounts(struct work_struct *work);
f7b422b1	23
a3dab293	24	static LIST_HEAD(nfs_automount_list);
65f27f38	25	static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
51d8fa6a TM	26	int nfs_mountpoint_expiry_timeout = 500 * HZ;
51d8fa6a TM	27
66f37509 AB	28	static struct vfsmount nfs_do_submount(const struct vfsmount mnt_parent,
	29	const struct dentry *dentry,
	30	struct nfs_fh *fh,
	31	struct nfs_fattr *fattr);
	32
f7b422b1 DH	33	/*
	34	* nfs_path - reconstruct the path given an arbitrary dentry
	35	* @base - arbitrary string to prepend to the path
54ceac45	36	* @droot - pointer to root dentry for mountpoint
f7b422b1 DH	37	* @dentry - pointer to dentry
	38	* @buffer - result buffer
	39	* @buflen - length of buffer
	40	*
	41	* Helper function for constructing the path from the
	42	* root dentry to an arbitrary hashed dentry.
	43	*
	44	* This is mainly for use in figuring out the path on the
	45	* server side when automounting on top of an existing partition.
	46	*/
54ceac45 DH	47	char nfs_path(const char base,
	48	const struct dentry *droot,
	49	const struct dentry *dentry,
f7b422b1 DH	50	char *buffer, ssize_t buflen)
	51	{
	52	char *end = buffer+buflen;
	53	int namelen;
	54
	55	*--end = '\0';
	56	buflen--;
	57	spin_lock(&dcache_lock);
54ceac45	58	while (!IS_ROOT(dentry) && dentry != droot) {
f7b422b1 DH	59	namelen = dentry->d_name.len;
	60	buflen -= namelen + 1;
	61	if (buflen < 0)
ce510193	62	goto Elong_unlock;
f7b422b1 DH	63	end -= namelen;
	64	memcpy(end, dentry->d_name.name, namelen);
	65	*--end = '/';
	66	dentry = dentry->d_parent;
	67	}
	68	spin_unlock(&dcache_lock);
0b75b35c TM	69	if (*end != '/') {
	70	if (--buflen < 0)
	71	goto Elong;
	72	*--end = '/';
	73	}
f7b422b1 DH	74	namelen = strlen(base);
	75	/* Strip off excess slashes in base string */
	76	while (namelen > 0 && base[namelen - 1] == '/')
	77	namelen--;
	78	buflen -= namelen;
	79	if (buflen < 0)
	80	goto Elong;
	81	end -= namelen;
	82	memcpy(end, base, namelen);
	83	return end;
ce510193 JT	84	Elong_unlock:
ce510193 JT	85	spin_unlock(&dcache_lock);
f7b422b1 DH	86	Elong:
	87	return ERR_PTR(-ENAMETOOLONG);
	88	}
	89
55a97593 TM	90	/*
	91	* nfs_follow_mountpoint - handle crossing a mountpoint on the server
	92	* @dentry - dentry of mountpoint
	93	* @nd - nameidata info
	94	*
	95	* When we encounter a mountpoint on the server, we want to set up
	96	* a mountpoint on the client too, to prevent inode numbers from
	97	* colliding, and to allow "df" to work properly.
	98	* On NFSv4, we also want to allow for the fact that different
	99	* filesystems may be migrated to different servers in a failover
	100	* situation, and that different filesystems may want to use
	101	* different security flavours.
	102	*/
	103	static void * nfs_follow_mountpoint(struct dentry dentry, struct nameidata nd)
	104	{
	105	struct vfsmount *mnt;
	106	struct nfs_server *server = NFS_SERVER(dentry->d_inode);
	107	struct dentry *parent;
a4d7f168 TM	108	struct nfs_fh *fh = NULL;
a4d7f168 TM	109	struct nfs_fattr *fattr = NULL;
55a97593 TM	110	int err;
55a97593 TM	111
54ceac45 DH	112	dprintk("--> nfs_follow_mountpoint()\n");
54ceac45 DH	113
44d5759d DL	114	err = -ESTALE;
	115	if (IS_ROOT(dentry))
	116	goto out_err;
	117
a4d7f168 TM	118	err = -ENOMEM;
	119	fh = nfs_alloc_fhandle();
	120	fattr = nfs_alloc_fattr();
	121	if (fh == NULL \|\| fattr == NULL)
	122	goto out_err;
	123
3110ff80	124	dprintk("%s: enter\n", __func__);
4ac91378 JB	125	dput(nd->path.dentry);
4ac91378 JB	126	nd->path.dentry = dget(dentry);
54ceac45	127
55a97593	128	/* Look it up again */
4ac91378	129	parent = dget_parent(nd->path.dentry);
8fa5c000	130	err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
4ac91378	131	&nd->path.dentry->d_name,
a4d7f168	132	fh, fattr);
55a97593 TM	133	dput(parent);
	134	if (err != 0)
	135	goto out_err;
	136
a4d7f168	137	if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
4ac91378	138	mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
6b97fd3d	139	else
a4d7f168 TM	140	mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
a4d7f168 TM	141	fattr);
55a97593 TM	142	err = PTR_ERR(mnt);
	143	if (IS_ERR(mnt))
	144	goto out_err;
	145
	146	mntget(mnt);
8d66bf54	147	err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags\|MNT_SHRINKABLE,
4ac91378	148	&nfs_automount_list);
55a97593 TM	149	if (err < 0) {
	150	mntput(mnt);
	151	if (err == -EBUSY)
	152	goto out_follow;
	153	goto out_err;
	154	}
31f31db1	155	path_put(&nd->path);
4ac91378 JB	156	nd->path.mnt = mnt;
4ac91378 JB	157	nd->path.dentry = dget(mnt->mnt_root);
51d8fa6a	158	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
55a97593	159	out:
a4d7f168 TM	160	nfs_free_fattr(fattr);
a4d7f168 TM	161	nfs_free_fhandle(fh);
3110ff80	162	dprintk("%s: done, returned %d\n", __func__, err);
54ceac45 DH	163
54ceac45 DH	164	dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
55a97593 TM	165	return ERR_PTR(err);
55a97593 TM	166	out_err:
1d957f9b	167	path_put(&nd->path);
55a97593 TM	168	goto out;
55a97593 TM	169	out_follow:
4ac91378	170	while (d_mountpoint(nd->path.dentry) &&
9393bd07	171	follow_down(&nd->path))
55a97593 TM	172	;
	173	err = 0;
	174	goto out;
	175	}
	176
92e1d5be	177	const struct inode_operations nfs_mountpoint_inode_operations = {
55a97593 TM	178	.follow_link = nfs_follow_mountpoint,
	179	.getattr = nfs_getattr,
	180	};
51d8fa6a	181
92e1d5be	182	const struct inode_operations nfs_referral_inode_operations = {
6b97fd3d MN	183	.follow_link = nfs_follow_mountpoint,
	184	};
	185
65f27f38	186	static void nfs_expire_automounts(struct work_struct *work)
51d8fa6a	187	{
65f27f38	188	struct list_head *list = &nfs_automount_list;
51d8fa6a TM	189
	190	mark_mounts_for_expiry(list);
	191	if (!list_empty(list))
	192	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
	193	}
	194
	195	void nfs_release_automount_timer(void)
	196	{
3d39c691	197	if (list_empty(&nfs_automount_list))
560aef74	198	cancel_delayed_work(&nfs_automount_task);
51d8fa6a	199	}
f7b422b1 DH	200
	201	/*
	202	* Clone a mountpoint of the appropriate type
	203	*/
509de811 DH	204	static struct vfsmount nfs_do_clone_mount(struct nfs_server server,
509de811 DH	205	const char *devname,
f7b422b1 DH	206	struct nfs_clone_mount *mountdata)
	207	{
	208	#ifdef CONFIG_NFS_V4
fd08d7e9	209	struct vfsmount *mnt = ERR_PTR(-EINVAL);
40c55319	210	switch (server->nfs_client->rpc_ops->version) {
f7b422b1 DH	211	case 2:
f7b422b1 DH	212	case 3:
54ceac45	213	mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
f7b422b1 DH	214	break;
f7b422b1 DH	215	case 4:
54ceac45	216	mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
f7b422b1 DH	217	}
	218	return mnt;
	219	#else
54ceac45	220	return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
f7b422b1 DH	221	#endif
	222	}
	223
	224	/**
	225	* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
	226	* @mnt_parent - mountpoint of parent directory
	227	* @dentry - parent directory
	228	* @fh - filehandle for new root dentry
	229	* @fattr - attributes for new root inode
	230	*
	231	*/
66f37509 AB	232	static struct vfsmount nfs_do_submount(const struct vfsmount mnt_parent,
	233	const struct dentry *dentry,
	234	struct nfs_fh *fh,
	235	struct nfs_fattr *fattr)
f7b422b1 DH	236	{
	237	struct nfs_clone_mount mountdata = {
	238	.sb = mnt_parent->mnt_sb,
	239	.dentry = dentry,
	240	.fh = fh,
	241	.fattr = fattr,
	242	};
	243	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
	244	char page = (char ) __get_free_page(GFP_USER);
	245	char *devname;
	246
54ceac45 DH	247	dprintk("--> nfs_do_submount()\n");
54ceac45 DH	248
3110ff80	249	dprintk("%s: submounting on %s/%s\n", __func__,
f7b422b1 DH	250	dentry->d_parent->d_name.name,
	251	dentry->d_name.name);
	252	if (page == NULL)
	253	goto out;
	254	devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
	255	mnt = (struct vfsmount *)devname;
	256	if (IS_ERR(devname))
	257	goto free_page;
	258	mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
	259	free_page:
	260	free_page((unsigned long)page);
	261	out:
3110ff80	262	dprintk("%s: done\n", __func__);
54ceac45 DH	263
54ceac45 DH	264	dprintk("<-- nfs_do_submount() = %p\n", mnt);
f7b422b1 DH	265	return mnt;
f7b422b1 DH	266	}