[mirror_ubuntu-bionic-kernel.git] / fs / nfs / namespace.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);

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);
	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", __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, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
			   &nfs_automount_list);
	if (err < 0) {
		mntput(mnt);
		if (err == -EBUSY)
			goto out_follow;
		goto out_err;
	}
	mntput(nd->path.mnt);
	dput(nd->path.dentry);
	nd->path.mnt = mnt;
	nd->path.dentry = dget(mnt->mnt_root);
	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
out:
	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.mnt, &nd->path.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);
}

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