[linux-2.6-block.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/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>
	18	#include <linux/vfs.h>
	19	#include <linux/fs.h>
	20	#include "cifsglob.h"
	21	#include "cifsproto.h"
	22	#include "cifsfs.h"
	23	#include "dns_resolve.h"
	24	#include "cifs_debug.h"
	25
8d142137	26	static LIST_HEAD(cifs_dfs_automount_list);
6d5ae0de	27
78d31a3a IM	28	static void cifs_dfs_expire_automounts(struct work_struct *work);
	29	static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
	30	cifs_dfs_expire_automounts);
	31	static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
	32
	33	static void cifs_dfs_expire_automounts(struct work_struct *work)
	34	{
	35	struct list_head *list = &cifs_dfs_automount_list;
	36
	37	mark_mounts_for_expiry(list);
	38	if (!list_empty(list))
	39	schedule_delayed_work(&cifs_dfs_automount_task,
	40	cifs_dfs_mountpoint_expiry_timeout);
	41	}
6d5ae0de	42
78d31a3a	43	void cifs_dfs_release_automount_timer(void)
6d5ae0de	44	{
78d31a3a IM	45	BUG_ON(!list_empty(&cifs_dfs_automount_list));
	46	cancel_delayed_work(&cifs_dfs_automount_task);
	47	flush_scheduled_work();
6d5ae0de IM	48	}
	49
	50	/**
	51	* cifs_get_share_name - extracts share name from UNC
	52	* @node_name: pointer to UNC string
	53	*
	54	* Extracts sharename form full UNC.
	55	* i.e. strips from UNC trailing path that is not part of share
	56	* name and fixup missing '\' in the begining of DFS node refferal
3ad2f3fb	57	* if necessary.
7b91e266	58	* Returns pointer to share name on success or ERR_PTR on error.
6d5ae0de IM	59	* Caller is responsible for freeing returned string.
	60	*/
	61	static char cifs_get_share_name(const char node_name)
	62	{
	63	int len;
	64	char *UNC;
	65	char *pSep;
	66
	67	len = strlen(node_name);
	68	UNC = kmalloc(len+2 /for term null and additional \ if it's missed /,
	69	GFP_KERNEL);
	70	if (!UNC)
7b91e266	71	return ERR_PTR(-ENOMEM);
6d5ae0de IM	72
	73	/* get share name and server name */
	74	if (node_name[1] != '\\') {
	75	UNC[0] = '\\';
	76	strncpy(UNC+1, node_name, len);
	77	len++;
	78	UNC[len] = 0;
	79	} else {
	80	strncpy(UNC, node_name, len);
	81	UNC[len] = 0;
	82	}
	83
	84	/* find server name end */
	85	pSep = memchr(UNC+2, '\\', len-2);
	86	if (!pSep) {
	87	cERROR(1, ("%s: no server name end in node name: %s",
55f78e17	88	__func__, node_name));
6d5ae0de	89	kfree(UNC);
7b91e266	90	return ERR_PTR(-EINVAL);
6d5ae0de IM	91	}
	92
	93	/* find sharename end */
	94	pSep++;
	95	pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
bf62fd88 IM	96	if (pSep) {
	97	/* trim path up to sharename end
	98	* now we have share name in UNC */
	99	*pSep = 0;
6d5ae0de	100	}
6d5ae0de IM	101
	102	return UNC;
	103	}
	104
	105
	106	/**
c6c00919	107	* cifs_compose_mount_options - creates mount options for refferral
6d5ae0de	108	* @sb_mountdata: parent/root DFS mount options (template)
c6c00919	109	* @fullpath: full path in UNC format
2c55608f	110	* @ref: server's referral
6d5ae0de IM	111	* @devname: pointer for saving device name
	112	*
	113	* creates mount options for submount based on template options sb_mountdata
	114	* and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
	115	*
	116	* Returns: pointer to new mount options or ERR_PTR.
	117	* Caller is responcible for freeing retunrned value if it is not error.
	118	*/
c6c00919 SF	119	char cifs_compose_mount_options(const char sb_mountdata,
c6c00919 SF	120	const char *fullpath,
2c55608f	121	const struct dfs_info3_param *ref,
366781c1	122	char **devname)
6d5ae0de IM	123	{
6d5ae0de IM	124	int rc;
c6fbba05	125	char *mountdata = NULL;
6d5ae0de IM	126	int md_len;
	127	char *tkn_e;
	128	char *srvIP = NULL;
	129	char sep = ',';
	130	int off, noff;
	131
	132	if (sb_mountdata == NULL)
	133	return ERR_PTR(-EINVAL);
	134
2c55608f	135	*devname = cifs_get_share_name(ref->node_name);
7b91e266 JL	136	if (IS_ERR(*devname)) {
	137	rc = PTR_ERR(*devname);
	138	*devname = NULL;
	139	goto compose_mount_options_err;
	140	}
	141
6d5ae0de IM	142	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
6d5ae0de IM	143	if (rc != 0) {
c6fbba05	144	cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
a419aef8	145	__func__, *devname, rc));
c6fbba05	146	goto compose_mount_options_err;
6d5ae0de	147	}
2c55608f IM	148	/* md_len = strlen(...) + 12 for 'sep+prefixpath='
	149	* assuming that we have 'unc=' and 'ip=' in
	150	* the original sb_mountdata
	151	*/
	152	md_len = strlen(sb_mountdata) + strlen(srvIP) +
	153	strlen(ref->node_name) + 12;
6d5ae0de IM	154	mountdata = kzalloc(md_len+1, GFP_KERNEL);
6d5ae0de IM	155	if (mountdata == NULL) {
c6fbba05 SF	156	rc = -ENOMEM;
c6fbba05 SF	157	goto compose_mount_options_err;
6d5ae0de IM	158	}
	159
	160	/* copy all options except of unc,ip,prefixpath */
	161	off = 0;
	162	if (strncmp(sb_mountdata, "sep=", 4) == 0) {
	163	sep = sb_mountdata[4];
	164	strncpy(mountdata, sb_mountdata, 5);
	165	off += 5;
	166	}
2c55608f IM	167
	168	do {
	169	tkn_e = strchr(sb_mountdata + off, sep);
	170	if (tkn_e == NULL)
	171	noff = strlen(sb_mountdata + off);
	172	else
	173	noff = tkn_e - (sb_mountdata + off) + 1;
	174
	175	if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
6d5ae0de IM	176	off += noff;
	177	continue;
	178	}
2c55608f	179	if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
6d5ae0de IM	180	off += noff;
	181	continue;
	182	}
2c55608f	183	if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
6d5ae0de IM	184	off += noff;
	185	continue;
	186	}
2c55608f	187	strncat(mountdata, sb_mountdata + off, noff);
6d5ae0de	188	off += noff;
2c55608f IM	189	} while (tkn_e);
2c55608f IM	190	strcat(mountdata, sb_mountdata + off);
6d5ae0de IM	191	mountdata[md_len] = '\0';
	192
	193	/* copy new IP and ref share name */
2c55608f IM	194	if (mountdata[strlen(mountdata) - 1] != sep)
	195	strncat(mountdata, &sep, 1);
	196	strcat(mountdata, "ip=");
6d5ae0de	197	strcat(mountdata, srvIP);
2c55608f IM	198	strncat(mountdata, &sep, 1);
2c55608f IM	199	strcat(mountdata, "unc=");
6d5ae0de IM	200	strcat(mountdata, *devname);
	201
	202	/* find & copy prefixpath */
2c55608f	203	tkn_e = strchr(ref->node_name + 2, '\\');
c6fbba05 SF	204	if (tkn_e == NULL) {
	205	/* invalid unc, missing share name*/
	206	rc = -EINVAL;
	207	goto compose_mount_options_err;
	208	}
2c55608f	209
2c55608f	210	tkn_e = strchr(tkn_e + 1, '\\');
c6fbba05	211	if (tkn_e \|\| (strlen(fullpath) - ref->path_consumed)) {
2c55608f IM	212	strncat(mountdata, &sep, 1);
	213	strcat(mountdata, "prefixpath=");
	214	if (tkn_e)
	215	strcat(mountdata, tkn_e + 1);
c6fbba05	216	strcat(mountdata, fullpath + ref->path_consumed);
6d5ae0de IM	217	}
6d5ae0de IM	218
55f78e17 HH	219	/cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));/
55f78e17 HH	220	/cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));/
6d5ae0de IM	221
	222	compose_mount_options_out:
	223	kfree(srvIP);
	224	return mountdata;
c6fbba05 SF	225
	226	compose_mount_options_err:
	227	kfree(mountdata);
	228	mountdata = ERR_PTR(rc);
	229	goto compose_mount_options_out;
6d5ae0de IM	230	}
	231
	232
366781c1	233	static struct vfsmount cifs_dfs_do_refmount(const struct vfsmount mnt_parent,
2c55608f	234	struct dentry dentry, const struct dfs_info3_param ref)
6d5ae0de IM	235	{
	236	struct cifs_sb_info *cifs_sb;
	237	struct vfsmount *mnt;
	238	char *mountdata;
366781c1	239	char *devname = NULL;
c6c00919	240	char *fullpath;
6d5ae0de IM	241
6d5ae0de IM	242	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
c6c00919 SF	243	/*
	244	* this function gives us a path with a double backslash prefix. We
	245	* require a single backslash for DFS.
	246	*/
	247	fullpath = build_path_from_dentry(dentry);
	248	if (!fullpath)
	249	return ERR_PTR(-ENOMEM);
	250
	251	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
	252	fullpath + 1, ref, &devname);
	253	kfree(fullpath);
6d5ae0de IM	254
	255	if (IS_ERR(mountdata))
	256	return (struct vfsmount *)mountdata;
	257
	258	mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
	259	kfree(mountdata);
	260	kfree(devname);
	261	return mnt;
	262
	263	}
	264
6d5ae0de IM	265	static int add_mount_helper(struct vfsmount newmnt, struct nameidata nd,
	266	struct list_head *mntlist)
	267	{
	268	/* stolen from afs code */
	269	int err;
	270
	271	mntget(newmnt);
7e1295d9	272	err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags \| MNT_SHRINKABLE, mntlist);
6d5ae0de IM	273	switch (err) {
6d5ae0de IM	274	case 0:
78d31a3a	275	path_put(&nd->path);
4ac91378 JB	276	nd->path.mnt = newmnt;
4ac91378 JB	277	nd->path.dentry = dget(newmnt->mnt_root);
78d31a3a IM	278	schedule_delayed_work(&cifs_dfs_automount_task,
78d31a3a IM	279	cifs_dfs_mountpoint_expiry_timeout);
6d5ae0de IM	280	break;
	281	case -EBUSY:
	282	/* someone else made a mount here whilst we were busy */
4ac91378	283	while (d_mountpoint(nd->path.dentry) &&
9393bd07	284	follow_down(&nd->path))
6d5ae0de IM	285	;
	286	err = 0;
	287	default:
	288	mntput(newmnt);
	289	break;
	290	}
	291	return err;
	292	}
	293
366781c1	294	static void dump_referral(const struct dfs_info3_param *ref)
6d5ae0de IM	295	{
	296	cFYI(1, ("DFS: ref path: %s", ref->path_name));
	297	cFYI(1, ("DFS: node path: %s", ref->node_name));
	298	cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
	299	cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
8aad018b	300	ref->path_consumed));
6d5ae0de IM	301	}
	302
	303
	304	static void*
	305	cifs_dfs_follow_mountpoint(struct dentry dentry, struct nameidata nd)
	306	{
	307	struct dfs_info3_param *referrals = NULL;
	308	unsigned int num_referrals = 0;
	309	struct cifs_sb_info *cifs_sb;
	310	struct cifsSesInfo *ses;
	311	char *full_path = NULL;
	312	int xid, i;
	313	int rc = 0;
	314	struct vfsmount *mnt = ERR_PTR(-ENOENT);
	315
55f78e17	316	cFYI(1, ("in %s", __func__));
6d5ae0de IM	317	BUG_ON(IS_ROOT(dentry));
	318
	319	xid = GetXid();
	320
4ac91378 JB	321	dput(nd->path.dentry);
4ac91378 JB	322	nd->path.dentry = dget(dentry);
6d5ae0de IM	323
	324	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
	325	ses = cifs_sb->tcon->ses;
	326
	327	if (!ses) {
	328	rc = -EINVAL;
	329	goto out_err;
	330	}
	331
c6fbba05 SF	332	/*
	333	* The MSDFS spec states that paths in DFS referral requests and
	334	* responses must be prefixed by a single '\' character instead of
	335	* the double backslashes usually used in the UNC. This function
	336	* gives us the latter, so we must adjust the result.
	337	*/
de2db8d7	338	full_path = build_path_from_dentry(dentry);
6d5ae0de IM	339	if (full_path == NULL) {
	340	rc = -ENOMEM;
	341	goto out_err;
	342	}
	343
c6fbba05	344	rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
6d5ae0de IM	345	&num_referrals, &referrals,
	346	cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
	347
	348	for (i = 0; i < num_referrals; i++) {
cf398e3a	349	int len;
6d5ae0de	350	dump_referral(referrals+i);
1af28ceb	351	/* connect to a node */
1af28ceb IM	352	len = strlen(referrals[i].node_name);
	353	if (len < 2) {
	354	cERROR(1, ("%s: Net Address path too short: %s",
55f78e17	355	__func__, referrals[i].node_name));
1af28ceb IM	356	rc = -EINVAL;
	357	goto out_err;
	358	}
	359	mnt = cifs_dfs_do_refmount(nd->path.mnt,
	360	nd->path.dentry, referrals + i);
	361	cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
6d5ae0de IM	362	referrals[i].node_name, mnt));
6d5ae0de IM	363
1af28ceb IM	364	/* complete mount procedure if we accured submount */
	365	if (!IS_ERR(mnt))
	366	break;
6d5ae0de IM	367	}
	368
	369	/* we need it cause for() above could exit without valid submount */
	370	rc = PTR_ERR(mnt);
	371	if (IS_ERR(mnt))
	372	goto out_err;
	373
6d5ae0de IM	374	rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
	375
	376	out:
	377	FreeXid(xid);
	378	free_dfs_info_array(referrals, num_referrals);
	379	kfree(full_path);
55f78e17	380	cFYI(1, ("leaving %s" , __func__));
6d5ae0de IM	381	return ERR_PTR(rc);
6d5ae0de IM	382	out_err:
1d957f9b	383	path_put(&nd->path);
6d5ae0de IM	384	goto out;
	385	}
	386
6e1d5dcc	387	const struct inode_operations cifs_dfs_referral_inode_operations = {
6d5ae0de IM	388	.follow_link = cifs_dfs_follow_mountpoint,
	389	};
	390