[CIFS] DFS support: provide shrinkable mounts
Signed-off-by: Igor Mammedov <niallain@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
new file mode 100644
index 0000000..15e31f8
--- /dev/null
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -0,0 +1,375 @@
+/*
+ * 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,
+};
+