[net-next-2.6.git] / fs / cifs / cifs_dfs_ref.c

/*
 *   Contains the CIFS DFS referral mounting routines used for handling
 *   traversal via DFS junction point
 *
 *   Copyright (c) 2007 Igor Mammedov
 *   Copyright (C) International Business Machines  Corp., 2008
 *   Author(s): Igor Mammedov (niallain@gmail.com)
 *		Steve French (sfrench@us.ibm.com)
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation; either version
 *   2 of the License, or (at your option) any later version.
 */

#include <linux/dcache.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/vfs.h>
#include <linux/fs.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifsfs.h"
#include "dns_resolve.h"
#include "cifs_debug.h"

static LIST_HEAD(cifs_dfs_automount_list);

static void cifs_dfs_expire_automounts(struct work_struct *work);
static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
			    cifs_dfs_expire_automounts);
static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;

static void cifs_dfs_expire_automounts(struct work_struct *work)
{
	struct list_head *list = &cifs_dfs_automount_list;

	mark_mounts_for_expiry(list);
	if (!list_empty(list))
		schedule_delayed_work(&cifs_dfs_automount_task,
				      cifs_dfs_mountpoint_expiry_timeout);
}

void cifs_dfs_release_automount_timer(void)
{
	BUG_ON(!list_empty(&cifs_dfs_automount_list));
	cancel_delayed_work(&cifs_dfs_automount_task);
	flush_scheduled_work();
}

/**
 * cifs_get_share_name	-	extracts share name from UNC
 * @node_name:	pointer to UNC string
 *
 * Extracts sharename form full UNC.
 * i.e. strips from UNC trailing path that is not part of share
 * name and fixup missing '\' in the begining of DFS node refferal
 * if necessary.
 * Returns pointer to share name on success or ERR_PTR on error.
 * Caller is responsible for freeing returned string.
 */
static char *cifs_get_share_name(const char *node_name)
{
	int len;
	char *UNC;
	char *pSep;

	len = strlen(node_name);
	UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
			 GFP_KERNEL);
	if (!UNC)
		return ERR_PTR(-ENOMEM);

	/* get share name and server name */
	if (node_name[1] != '\\') {
		UNC[0] = '\\';
		strncpy(UNC+1, node_name, len);
		len++;
		UNC[len] = 0;
	} else {
		strncpy(UNC, node_name, len);
		UNC[len] = 0;
	}

	/* find server name end */
	pSep = memchr(UNC+2, '\\', len-2);
	if (!pSep) {
		cERROR(1, ("%s: no server name end in node name: %s",
			__func__, node_name));
		kfree(UNC);
		return ERR_PTR(-EINVAL);
	}

	/* find sharename end */
	pSep++;
	pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
	if (pSep) {
		/* trim path up to sharename end
		 * now we have share name in UNC */
		*pSep = 0;
	}

	return UNC;
}


/**
 * cifs_compose_mount_options	-	creates mount options for refferral
 * @sb_mountdata:	parent/root DFS mount options (template)
 * @fullpath:		full path in UNC format
 * @ref:		server's referral
 * @devname:		pointer for saving device name
 *
 * creates mount options for submount based on template options sb_mountdata
 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
 *
 * Returns: pointer to new mount options or ERR_PTR.
 * Caller is responcible for freeing retunrned value if it is not error.
 */
char *cifs_compose_mount_options(const char *sb_mountdata,
				   const char *fullpath,
				   const struct dfs_info3_param *ref,
				   char **devname)
{
	int rc;
	char *mountdata = NULL;
	int md_len;
	char *tkn_e;
	char *srvIP = NULL;
	char sep = ',';
	int off, noff;

	if (sb_mountdata == NULL)
		return ERR_PTR(-EINVAL);

	*devname = cifs_get_share_name(ref->node_name);
	if (IS_ERR(*devname)) {
		rc = PTR_ERR(*devname);
		*devname = NULL;
		goto compose_mount_options_err;
	}

	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
	if (rc != 0) {
		cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
			  __func__, *devname, rc));
		goto compose_mount_options_err;
	}
	/* md_len = strlen(...) + 12 for 'sep+prefixpath='
	 * assuming that we have 'unc=' and 'ip=' in
	 * the original sb_mountdata
	 */
	md_len = strlen(sb_mountdata) + strlen(srvIP) +
		strlen(ref->node_name) + 12;
	mountdata = kzalloc(md_len+1, GFP_KERNEL);
	if (mountdata == NULL) {
		rc = -ENOMEM;
		goto compose_mount_options_err;
	}

	/* copy all options except of unc,ip,prefixpath */
	off = 0;
	if (strncmp(sb_mountdata, "sep=", 4) == 0) {
			sep = sb_mountdata[4];
			strncpy(mountdata, sb_mountdata, 5);
			off += 5;
	}

	do {
		tkn_e = strchr(sb_mountdata + off, sep);
		if (tkn_e == NULL)
			noff = strlen(sb_mountdata + off);
		else
			noff = tkn_e - (sb_mountdata + off) + 1;

		if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
			off += noff;
			continue;
		}
		if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
			off += noff;
			continue;
		}
		if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
			off += noff;
			continue;
		}
		strncat(mountdata, sb_mountdata + off, noff);
		off += noff;
	} while (tkn_e);
	strcat(mountdata, sb_mountdata + off);
	mountdata[md_len] = '\0';

	/* copy new IP and ref share name */
	if (mountdata[strlen(mountdata) - 1] != sep)
		strncat(mountdata, &sep, 1);
	strcat(mountdata, "ip=");
	strcat(mountdata, srvIP);
	strncat(mountdata, &sep, 1);
	strcat(mountdata, "unc=");
	strcat(mountdata, *devname);

	/* find & copy prefixpath */
	tkn_e = strchr(ref->node_name + 2, '\\');
	if (tkn_e == NULL) {
		/* invalid unc, missing share name*/
		rc = -EINVAL;
		goto compose_mount_options_err;
	}

	tkn_e = strchr(tkn_e + 1, '\\');
	if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
		strncat(mountdata, &sep, 1);
		strcat(mountdata, "prefixpath=");
		if (tkn_e)
			strcat(mountdata, tkn_e + 1);
		strcat(mountdata, fullpath + ref->path_consumed);
	}

	/*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
	/*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/

compose_mount_options_out:
	kfree(srvIP);
	return mountdata;

compose_mount_options_err:
	kfree(mountdata);
	mountdata = ERR_PTR(rc);
	goto compose_mount_options_out;
}


static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
		struct dentry *dentry, const struct dfs_info3_param *ref)
{
	struct cifs_sb_info *cifs_sb;
	struct vfsmount *mnt;
	char *mountdata;
	char *devname = NULL;
	char *fullpath;

	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
	/*
	 * this function gives us a path with a double backslash prefix. We
	 * require a single backslash for DFS.
	 */
	fullpath = build_path_from_dentry(dentry);
	if (!fullpath)
		return ERR_PTR(-ENOMEM);

	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
			fullpath + 1, ref, &devname);
	kfree(fullpath);

	if (IS_ERR(mountdata))
		return (struct vfsmount *)mountdata;

	mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
	kfree(mountdata);
	kfree(devname);
	return mnt;

}

static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
				struct list_head *mntlist)
{
	/* stolen from afs code */
	int err;

	mntget(newmnt);
	err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist);
	switch (err) {
	case 0:
		path_put(&nd->path);
		nd->path.mnt = newmnt;
		nd->path.dentry = dget(newmnt->mnt_root);
		schedule_delayed_work(&cifs_dfs_automount_task,
				      cifs_dfs_mountpoint_expiry_timeout);
		break;
	case -EBUSY:
		/* someone else made a mount here whilst we were busy */
		while (d_mountpoint(nd->path.dentry) &&
		       follow_down(&nd->path))
			;
		err = 0;
	default:
		mntput(newmnt);
		break;
	}
	return err;
}

static void dump_referral(const struct dfs_info3_param *ref)
{
	cFYI(1, ("DFS: ref path: %s", ref->path_name));
	cFYI(1, ("DFS: node path: %s", ref->node_name));
	cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
	cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
				ref->path_consumed));
}


static void*
cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
{
	struct dfs_info3_param *referrals = NULL;
	unsigned int num_referrals = 0;
	struct cifs_sb_info *cifs_sb;
	struct cifsSesInfo *ses;
	char *full_path = NULL;
	int xid, i;
	int rc = 0;
	struct vfsmount *mnt = ERR_PTR(-ENOENT);

	cFYI(1, ("in %s", __func__));
	BUG_ON(IS_ROOT(dentry));

	xid = GetXid();

	dput(nd->path.dentry);
	nd->path.dentry = dget(dentry);

	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
	ses = cifs_sb->tcon->ses;

	if (!ses) {
		rc = -EINVAL;
		goto out_err;
	}

	/*
	 * The MSDFS spec states that paths in DFS referral requests and
	 * responses must be prefixed by a single '\' character instead of
	 * the double backslashes usually used in the UNC. This function
	 * gives us the latter, so we must adjust the result.
	 */
	full_path = build_path_from_dentry(dentry);
	if (full_path == NULL) {
		rc = -ENOMEM;
		goto out_err;
	}

	rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
		&num_referrals, &referrals,
		cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);

	for (i = 0; i < num_referrals; i++) {
		int len;
		dump_referral(referrals+i);
		/* connect to a node */
		len = strlen(referrals[i].node_name);
		if (len < 2) {
			cERROR(1, ("%s: Net Address path too short: %s",
					__func__, referrals[i].node_name));
			rc = -EINVAL;
			goto out_err;
		}
		mnt = cifs_dfs_do_refmount(nd->path.mnt,
				nd->path.dentry, referrals + i);
		cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
					referrals[i].node_name, mnt));

		/* complete mount procedure if we accured submount */
		if (!IS_ERR(mnt))
			break;
	}

	/* we need it cause for() above could exit without valid submount */
	rc = PTR_ERR(mnt);
	if (IS_ERR(mnt))
		goto out_err;

	rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);

out:
	FreeXid(xid);
	free_dfs_info_array(referrals, num_referrals);
	kfree(full_path);
	cFYI(1, ("leaving %s" , __func__));
	return ERR_PTR(rc);
out_err:
	path_put(&nd->path);
	goto out;
}

const struct inode_operations cifs_dfs_referral_inode_operations = {
	.follow_link = cifs_dfs_follow_mountpoint,
};
Commit	Line	Data
6d5ae0de IM	1	/*
	2	* Contains the CIFS DFS referral mounting routines used for handling
	3	* traversal via DFS junction point
	4	*
	5	* Copyright (c) 2007 Igor Mammedov
366781c1	6	* Copyright (C) International Business Machines Corp., 2008
6d5ae0de	7	* Author(s): Igor Mammedov (niallain@gmail.com)
366781c1	8	* Steve French (sfrench@us.ibm.com)
6d5ae0de IM	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License
	11	* as published by the Free Software Foundation; either version
	12	* 2 of the License, or (at your option) any later version.
	13	*/
	14
	15	#include <linux/dcache.h>
	16	#include <linux/mount.h>
	17	#include <linux/namei.h>
5a0e3ad6	18	#include <linux/slab.h>
6d5ae0de IM	19	#include <linux/vfs.h>
	20	#include <linux/fs.h>
	21	#include "cifsglob.h"
	22	#include "cifsproto.h"
	23	#include "cifsfs.h"
	24	#include "dns_resolve.h"
	25	#include "cifs_debug.h"
	26
8d142137	27	static LIST_HEAD(cifs_dfs_automount_list);
6d5ae0de	28
78d31a3a IM	29	static void cifs_dfs_expire_automounts(struct work_struct *work);
	30	static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
	31	cifs_dfs_expire_automounts);
	32	static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
	33
	34	static void cifs_dfs_expire_automounts(struct work_struct *work)
	35	{
	36	struct list_head *list = &cifs_dfs_automount_list;
	37
	38	mark_mounts_for_expiry(list);
	39	if (!list_empty(list))
	40	schedule_delayed_work(&cifs_dfs_automount_task,
	41	cifs_dfs_mountpoint_expiry_timeout);
	42	}
6d5ae0de	43
78d31a3a	44	void cifs_dfs_release_automount_timer(void)
6d5ae0de	45	{
78d31a3a IM	46	BUG_ON(!list_empty(&cifs_dfs_automount_list));
	47	cancel_delayed_work(&cifs_dfs_automount_task);
	48	flush_scheduled_work();
6d5ae0de IM	49	}
	50
	51	/**
	52	* cifs_get_share_name - extracts share name from UNC
	53	* @node_name: pointer to UNC string
	54	*
	55	* Extracts sharename form full UNC.
	56	* i.e. strips from UNC trailing path that is not part of share
	57	* name and fixup missing '\' in the begining of DFS node refferal
3ad2f3fb	58	* if necessary.
7b91e266	59	* Returns pointer to share name on success or ERR_PTR on error.
6d5ae0de IM	60	* Caller is responsible for freeing returned string.
	61	*/
	62	static char cifs_get_share_name(const char node_name)
	63	{
	64	int len;
	65	char *UNC;
	66	char *pSep;
	67
	68	len = strlen(node_name);
	69	UNC = kmalloc(len+2 /for term null and additional \ if it's missed /,
	70	GFP_KERNEL);
	71	if (!UNC)
7b91e266	72	return ERR_PTR(-ENOMEM);
6d5ae0de IM	73
	74	/* get share name and server name */
	75	if (node_name[1] != '\\') {
	76	UNC[0] = '\\';
	77	strncpy(UNC+1, node_name, len);
	78	len++;
	79	UNC[len] = 0;
	80	} else {
	81	strncpy(UNC, node_name, len);
	82	UNC[len] = 0;
	83	}
	84
	85	/* find server name end */
	86	pSep = memchr(UNC+2, '\\', len-2);
	87	if (!pSep) {
	88	cERROR(1, ("%s: no server name end in node name: %s",
55f78e17	89	__func__, node_name));
6d5ae0de	90	kfree(UNC);
7b91e266	91	return ERR_PTR(-EINVAL);
6d5ae0de IM	92	}
	93
	94	/* find sharename end */
	95	pSep++;
	96	pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
bf62fd88 IM	97	if (pSep) {
	98	/* trim path up to sharename end
	99	* now we have share name in UNC */
	100	*pSep = 0;
6d5ae0de	101	}
6d5ae0de IM	102
	103	return UNC;
	104	}
	105
	106
	107	/**
c6c00919	108	* cifs_compose_mount_options - creates mount options for refferral
6d5ae0de	109	* @sb_mountdata: parent/root DFS mount options (template)
c6c00919	110	* @fullpath: full path in UNC format
2c55608f	111	* @ref: server's referral
6d5ae0de IM	112	* @devname: pointer for saving device name
	113	*
	114	* creates mount options for submount based on template options sb_mountdata
	115	* and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
	116	*
	117	* Returns: pointer to new mount options or ERR_PTR.
	118	* Caller is responcible for freeing retunrned value if it is not error.
	119	*/
c6c00919 SF	120	char cifs_compose_mount_options(const char sb_mountdata,
c6c00919 SF	121	const char *fullpath,
2c55608f	122	const struct dfs_info3_param *ref,
366781c1	123	char **devname)
6d5ae0de IM	124	{
6d5ae0de IM	125	int rc;
c6fbba05	126	char *mountdata = NULL;
6d5ae0de IM	127	int md_len;
	128	char *tkn_e;
	129	char *srvIP = NULL;
	130	char sep = ',';
	131	int off, noff;
	132
	133	if (sb_mountdata == NULL)
	134	return ERR_PTR(-EINVAL);
	135
2c55608f	136	*devname = cifs_get_share_name(ref->node_name);
7b91e266 JL	137	if (IS_ERR(*devname)) {
	138	rc = PTR_ERR(*devname);
	139	*devname = NULL;
	140	goto compose_mount_options_err;
	141	}
	142
6d5ae0de IM	143	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
6d5ae0de IM	144	if (rc != 0) {
c6fbba05	145	cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
a419aef8	146	__func__, *devname, rc));
c6fbba05	147	goto compose_mount_options_err;
6d5ae0de	148	}
2c55608f IM	149	/* md_len = strlen(...) + 12 for 'sep+prefixpath='
	150	* assuming that we have 'unc=' and 'ip=' in
	151	* the original sb_mountdata
	152	*/
	153	md_len = strlen(sb_mountdata) + strlen(srvIP) +
	154	strlen(ref->node_name) + 12;
6d5ae0de IM	155	mountdata = kzalloc(md_len+1, GFP_KERNEL);
6d5ae0de IM	156	if (mountdata == NULL) {
c6fbba05 SF	157	rc = -ENOMEM;
c6fbba05 SF	158	goto compose_mount_options_err;
6d5ae0de IM	159	}
	160
	161	/* copy all options except of unc,ip,prefixpath */
	162	off = 0;
	163	if (strncmp(sb_mountdata, "sep=", 4) == 0) {
	164	sep = sb_mountdata[4];
	165	strncpy(mountdata, sb_mountdata, 5);
	166	off += 5;
	167	}
2c55608f IM	168
	169	do {
	170	tkn_e = strchr(sb_mountdata + off, sep);
	171	if (tkn_e == NULL)
	172	noff = strlen(sb_mountdata + off);
	173	else
	174	noff = tkn_e - (sb_mountdata + off) + 1;
	175
	176	if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
6d5ae0de IM	177	off += noff;
	178	continue;
	179	}
2c55608f	180	if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
6d5ae0de IM	181	off += noff;
	182	continue;
	183	}
2c55608f	184	if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
6d5ae0de IM	185	off += noff;
	186	continue;
	187	}
2c55608f	188	strncat(mountdata, sb_mountdata + off, noff);
6d5ae0de	189	off += noff;
2c55608f IM	190	} while (tkn_e);
2c55608f IM	191	strcat(mountdata, sb_mountdata + off);
6d5ae0de IM	192	mountdata[md_len] = '\0';
	193
	194	/* copy new IP and ref share name */
2c55608f IM	195	if (mountdata[strlen(mountdata) - 1] != sep)
	196	strncat(mountdata, &sep, 1);
	197	strcat(mountdata, "ip=");
6d5ae0de	198	strcat(mountdata, srvIP);
2c55608f IM	199	strncat(mountdata, &sep, 1);
2c55608f IM	200	strcat(mountdata, "unc=");
6d5ae0de IM	201	strcat(mountdata, *devname);
	202
	203	/* find & copy prefixpath */
2c55608f	204	tkn_e = strchr(ref->node_name + 2, '\\');
c6fbba05 SF	205	if (tkn_e == NULL) {
	206	/* invalid unc, missing share name*/
	207	rc = -EINVAL;
	208	goto compose_mount_options_err;
	209	}
2c55608f	210
2c55608f	211	tkn_e = strchr(tkn_e + 1, '\\');
c6fbba05	212	if (tkn_e \|\| (strlen(fullpath) - ref->path_consumed)) {
2c55608f IM	213	strncat(mountdata, &sep, 1);
	214	strcat(mountdata, "prefixpath=");
	215	if (tkn_e)
	216	strcat(mountdata, tkn_e + 1);
c6fbba05	217	strcat(mountdata, fullpath + ref->path_consumed);
6d5ae0de IM	218	}
6d5ae0de IM	219
55f78e17 HH	220	/cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));/
55f78e17 HH	221	/cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));/
6d5ae0de IM	222
	223	compose_mount_options_out:
	224	kfree(srvIP);
	225	return mountdata;
c6fbba05 SF	226
	227	compose_mount_options_err:
	228	kfree(mountdata);
	229	mountdata = ERR_PTR(rc);
	230	goto compose_mount_options_out;
6d5ae0de IM	231	}
	232
	233
366781c1	234	static struct vfsmount cifs_dfs_do_refmount(const struct vfsmount mnt_parent,
2c55608f	235	struct dentry dentry, const struct dfs_info3_param ref)
6d5ae0de IM	236	{
	237	struct cifs_sb_info *cifs_sb;
	238	struct vfsmount *mnt;
	239	char *mountdata;
366781c1	240	char *devname = NULL;
c6c00919	241	char *fullpath;
6d5ae0de IM	242
6d5ae0de IM	243	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
c6c00919 SF	244	/*
	245	* this function gives us a path with a double backslash prefix. We
	246	* require a single backslash for DFS.
	247	*/
	248	fullpath = build_path_from_dentry(dentry);
	249	if (!fullpath)
	250	return ERR_PTR(-ENOMEM);
	251
	252	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
	253	fullpath + 1, ref, &devname);
	254	kfree(fullpath);
6d5ae0de IM	255
	256	if (IS_ERR(mountdata))
	257	return (struct vfsmount *)mountdata;
	258
	259	mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
	260	kfree(mountdata);
	261	kfree(devname);
	262	return mnt;
	263
	264	}
	265
6d5ae0de IM	266	static int add_mount_helper(struct vfsmount newmnt, struct nameidata nd,
	267	struct list_head *mntlist)
	268	{
	269	/* stolen from afs code */
	270	int err;
	271
	272	mntget(newmnt);
7e1295d9	273	err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags \| MNT_SHRINKABLE, mntlist);
6d5ae0de IM	274	switch (err) {
6d5ae0de IM	275	case 0:
78d31a3a	276	path_put(&nd->path);
4ac91378 JB	277	nd->path.mnt = newmnt;
4ac91378 JB	278	nd->path.dentry = dget(newmnt->mnt_root);
78d31a3a IM	279	schedule_delayed_work(&cifs_dfs_automount_task,
78d31a3a IM	280	cifs_dfs_mountpoint_expiry_timeout);
6d5ae0de IM	281	break;
	282	case -EBUSY:
	283	/* someone else made a mount here whilst we were busy */
4ac91378	284	while (d_mountpoint(nd->path.dentry) &&
9393bd07	285	follow_down(&nd->path))
6d5ae0de IM	286	;
	287	err = 0;
	288	default:
	289	mntput(newmnt);
	290	break;
	291	}
	292	return err;
	293	}
	294
366781c1	295	static void dump_referral(const struct dfs_info3_param *ref)
6d5ae0de IM	296	{
	297	cFYI(1, ("DFS: ref path: %s", ref->path_name));
	298	cFYI(1, ("DFS: node path: %s", ref->node_name));
	299	cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
	300	cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
8aad018b	301	ref->path_consumed));
6d5ae0de IM	302	}
	303
	304
	305	static void*
	306	cifs_dfs_follow_mountpoint(struct dentry dentry, struct nameidata nd)
	307	{
	308	struct dfs_info3_param *referrals = NULL;
	309	unsigned int num_referrals = 0;
	310	struct cifs_sb_info *cifs_sb;
	311	struct cifsSesInfo *ses;
	312	char *full_path = NULL;
	313	int xid, i;
	314	int rc = 0;
	315	struct vfsmount *mnt = ERR_PTR(-ENOENT);
	316
55f78e17	317	cFYI(1, ("in %s", __func__));
6d5ae0de IM	318	BUG_ON(IS_ROOT(dentry));
	319
	320	xid = GetXid();
	321
4ac91378 JB	322	dput(nd->path.dentry);
4ac91378 JB	323	nd->path.dentry = dget(dentry);
6d5ae0de IM	324
	325	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
	326	ses = cifs_sb->tcon->ses;
	327
	328	if (!ses) {
	329	rc = -EINVAL;
	330	goto out_err;
	331	}
	332
c6fbba05 SF	333	/*
	334	* The MSDFS spec states that paths in DFS referral requests and
	335	* responses must be prefixed by a single '\' character instead of
	336	* the double backslashes usually used in the UNC. This function
	337	* gives us the latter, so we must adjust the result.
	338	*/
de2db8d7	339	full_path = build_path_from_dentry(dentry);
6d5ae0de IM	340	if (full_path == NULL) {
	341	rc = -ENOMEM;
	342	goto out_err;
	343	}
	344
c6fbba05	345	rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
6d5ae0de IM	346	&num_referrals, &referrals,
	347	cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
	348
	349	for (i = 0; i < num_referrals; i++) {
cf398e3a	350	int len;
6d5ae0de	351	dump_referral(referrals+i);
1af28ceb	352	/* connect to a node */
1af28ceb IM	353	len = strlen(referrals[i].node_name);
	354	if (len < 2) {
	355	cERROR(1, ("%s: Net Address path too short: %s",
55f78e17	356	__func__, referrals[i].node_name));
1af28ceb IM	357	rc = -EINVAL;
	358	goto out_err;
	359	}
	360	mnt = cifs_dfs_do_refmount(nd->path.mnt,
	361	nd->path.dentry, referrals + i);
	362	cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
6d5ae0de IM	363	referrals[i].node_name, mnt));
6d5ae0de IM	364
1af28ceb IM	365	/* complete mount procedure if we accured submount */
	366	if (!IS_ERR(mnt))
	367	break;
6d5ae0de IM	368	}
	369
	370	/* we need it cause for() above could exit without valid submount */
	371	rc = PTR_ERR(mnt);
	372	if (IS_ERR(mnt))
	373	goto out_err;
	374
6d5ae0de IM	375	rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
	376
	377	out:
	378	FreeXid(xid);
	379	free_dfs_info_array(referrals, num_referrals);
	380	kfree(full_path);
55f78e17	381	cFYI(1, ("leaving %s" , __func__));
6d5ae0de IM	382	return ERR_PTR(rc);
6d5ae0de IM	383	out_err:
1d957f9b	384	path_put(&nd->path);
6d5ae0de IM	385	goto out;
	386	}
	387
6e1d5dcc	388	const struct inode_operations cifs_dfs_referral_inode_operations = {
6d5ae0de IM	389	.follow_link = cifs_dfs_follow_mountpoint,
	390	};
	391