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Commit 6d5ae0de authored by Igor Mammedov's avatar Igor Mammedov Committed by Steve French
Browse files

[CIFS] DFS support: provide shrinkable mounts 



Signed-off-by: default avatarIgor Mammedov <niallain@gmail.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent ed2b9170

fs/cifs/Makefile

+1 −1
Original line number Original line Diff line number Diff line
@@ -10,4 +10,4 @@ cifs-y := cifsfs.o cifssmb.o cifs_debug.o connect.o dir.o file.o inode.o \ 




cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o

cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o





cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o
 
cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o

fs/cifs/cifs_dfs_ref.c

0 → 100644
+375 −0
Original line number Original line Diff line number Diff line 
/*

 *   Contains the CIFS DFS referral mounting routines used for handling

 *   traversal via DFS junction point

 *

 *   Copyright (c) 2007 Igor Mammedov

 *   Author(s): Igor Mammedov (niallain@gmail.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"



LIST_HEAD(cifs_dfs_automount_list);



/*

 * DFS functions

*/



void dfs_shrink_umount_helper(struct vfsmount *vfsmnt)

{

	mark_mounts_for_expiry(&cifs_dfs_automount_list);

	mark_mounts_for_expiry(&cifs_dfs_automount_list);

	shrink_submounts(vfsmnt, &cifs_dfs_automount_list);

}



/**

 * 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 neccessary.

 * Returns pointer to share name on success or NULL 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 NULL;



	/* 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",

			__FUNCTION__, node_name));

		kfree(UNC);

		return NULL;

	}



	/* find sharename end */

	pSep++;

	pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));

	if (!pSep) {

		cERROR(1, ("%s:2 cant find share name in node name: %s",

			__FUNCTION__, node_name));

		kfree(UNC);

		return NULL;

	}

	/* trim path up to sharename end

	 *          * now we have share name in UNC */

	*pSep = 0;



	return UNC;

}





/**

 * compose_mount_options	-	creates mount options for refferral

 * @sb_mountdata:	parent/root DFS mount options (template)

 * @ref_unc:		refferral server UNC

 * @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 *compose_mount_options(const char *sb_mountdata, const char *ref_unc,

				char **devname)

{

	int rc;

	char *mountdata;

	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_unc);

	rc = dns_resolve_server_name_to_ip(*devname, &srvIP);

	if (rc != 0) {

		cERROR(1, ("%s: Failed to resolve server part of %s to IP",

			  __FUNCTION__, *devname));

		mountdata = ERR_PTR(rc);

		goto compose_mount_options_out;

	}

	md_len = strlen(sb_mountdata) + strlen(srvIP) + strlen(ref_unc) + 3;

	mountdata = kzalloc(md_len+1, GFP_KERNEL);

	if (mountdata == NULL) {

		mountdata = ERR_PTR(-ENOMEM);

		goto compose_mount_options_out;

	}



	/* 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;

	}

	while ((tkn_e = strchr(sb_mountdata+off, sep))) {

		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=", 3) == 0) {

			off += noff;

			continue;

		}

		strncat(mountdata, sb_mountdata+off, noff);

		off += noff;

	}

	strcat(mountdata, sb_mountdata+off);

	mountdata[md_len] = '\0';



	/* copy new IP and ref share name */

	strcat(mountdata, ",ip=");

	strcat(mountdata, srvIP);

	strcat(mountdata, ",unc=");

	strcat(mountdata, *devname);



	/* find & copy prefixpath */

	tkn_e = strchr(ref_unc+2, '\\');

	if (tkn_e) {

		tkn_e = strchr(tkn_e+1, '\\');

		if (tkn_e) {

			strcat(mountdata, ",prefixpath=");

			strcat(mountdata, tkn_e);

		}

	}



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

	/*cFYI(1, ("%s: submount mountdata: %s", __FUNCTION__, mountdata ));*/



compose_mount_options_out:

	kfree(srvIP);

	return mountdata;

}





struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,

		struct dentry *dentry, char *ref_unc)

{

	struct cifs_sb_info *cifs_sb;

	struct vfsmount *mnt;

	char *mountdata;

	char *devname;



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

	mountdata = compose_mount_options(cifs_sb->mountdata,

						ref_unc, &devname);



	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 char *build_full_dfs_path_from_dentry(struct dentry *dentry)

{

	char *full_path = NULL;

	char *search_path;

	char *tmp_path;

	size_t l_max_len;

	struct cifs_sb_info *cifs_sb;



	if (dentry->d_inode == NULL)

		return NULL;



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



	if (cifs_sb->tcon == NULL)

		return NULL;



	search_path = build_path_from_dentry(dentry);

	if (search_path == NULL)

		return NULL;



	if (cifs_sb->tcon->Flags & SMB_SHARE_IS_IN_DFS) {

		/* we should use full path name to correct working with DFS */

		l_max_len = strnlen(cifs_sb->tcon->treeName, MAX_TREE_SIZE+1) +

					strnlen(search_path, MAX_PATHCONF) + 1;

		tmp_path = kmalloc(l_max_len, GFP_KERNEL);

		if (tmp_path == NULL) {

			kfree(search_path);

			return NULL;

		}

		strncpy(tmp_path, cifs_sb->tcon->treeName, l_max_len);

		strcat(tmp_path, search_path);

		tmp_path[l_max_len-1] = 0;

		full_path = tmp_path;

		kfree(search_path);

	} else {

		full_path = search_path;

	}

	return full_path;

}



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, nd->mnt->mnt_flags, mntlist);

	switch (err) {

	case 0:

		dput(nd->dentry);

		mntput(nd->mnt);

		nd->mnt = newmnt;

		nd->dentry = dget(newmnt->mnt_root);

		break;

	case -EBUSY:

		/* someone else made a mount here whilst we were busy */

		while (d_mountpoint(nd->dentry) &&

		       follow_down(&nd->mnt, &nd->dentry))

			;

		err = 0;

	default:

		mntput(newmnt);

		break;

	}

	return err;

}



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->PathConsumed));

}





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", __FUNCTION__));

	BUG_ON(IS_ROOT(dentry));



	xid = GetXid();



	dput(nd->dentry);

	nd->dentry = dget(dentry);



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

	ses = cifs_sb->tcon->ses;



	if (!ses) {

		rc = -EINVAL;

		goto out_err;

	}



	full_path = build_full_dfs_path_from_dentry(dentry);

	if (full_path == NULL) {

		rc = -ENOMEM;

		goto out_err;

	}



	rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls,

		&num_referrals, &referrals,

		cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);



	for (i = 0; i < num_referrals; i++) {

		dump_referral(referrals+i);

		/* connect to a storage node */

		if (referrals[i].flags & DFSREF_STORAGE_SERVER) {

			int len;

			len = strlen(referrals[i].node_name);

			if (len < 2) {

				cERROR(1, ("%s: Net Address path too short: %s",

					__FUNCTION__, referrals[i].node_name));

				rc = -EINVAL;

				goto out_err;

			}

			mnt = cifs_dfs_do_refmount(nd->mnt, nd->dentry,

						referrals[i].node_name);

			cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p",

					 __FUNCTION__,

					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;



	nd->mnt->mnt_flags |= MNT_SHRINKABLE;

	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" , __FUNCTION__));

	return ERR_PTR(rc);

out_err:

	path_release(nd);

	goto out;

}



struct inode_operations cifs_dfs_referral_inode_operations = {

	.follow_link = cifs_dfs_follow_mountpoint,

};

fs/cifs/cifsfs.c

+4 −0
Original line number Original line Diff line number Diff line
@@ -471,6 +471,10 @@ static void cifs_umount_begin(struct vfsmount *vfsmnt, int flags) 
	struct cifs_sb_info *cifs_sb;

	struct cifs_sb_info *cifs_sb;

	struct cifsTconInfo *tcon;

	struct cifsTconInfo *tcon;





#ifdef CONFIG_CIFS_DFS_UPCALL

	dfs_shrink_umount_helper(vfsmnt);

#endif /* CONFIG CIFS_DFS_UPCALL */



	if (!(flags & MNT_FORCE))

	if (!(flags & MNT_FORCE))

		return;

		return;

	cifs_sb = CIFS_SB(vfsmnt->mnt_sb);

	cifs_sb = CIFS_SB(vfsmnt->mnt_sb);

fs/cifs/cifsfs.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -61,6 +61,10 @@ extern int cifs_setattr(struct dentry *, struct iattr *); 




extern const struct inode_operations cifs_file_inode_ops;

extern const struct inode_operations cifs_file_inode_ops;

extern const struct inode_operations cifs_symlink_inode_ops;

extern const struct inode_operations cifs_symlink_inode_ops;

extern struct list_head cifs_dfs_automount_list;

extern struct inode_operations cifs_dfs_referral_inode_operations;









/* Functions related to files and directories */

/* Functions related to files and directories */

extern const struct file_operations cifs_file_ops;

extern const struct file_operations cifs_file_ops;

fs/cifs/cifsproto.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -102,6 +102,9 @@ extern int mode_to_acl(struct inode *inode, const char *path, __u64); 
extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,

extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,

			const char *);

			const char *);

extern int cifs_umount(struct super_block *, struct cifs_sb_info *);

extern int cifs_umount(struct super_block *, struct cifs_sb_info *);

#ifdef CONFIG_CIFS_DFS_UPCALL

extern void dfs_shrink_umount_helper(struct vfsmount *vfsmnt);

#endif

void cifs_proc_init(void);

void cifs_proc_init(void);

void cifs_proc_clean(void);

void cifs_proc_clean(void);