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![Paulo Alcantara](/assets/img/avatar_default.png)
Set the DFS root session pointer earlier when creating a new SMB session to prevent racing with smb2_reconnect(), cifs_reconnect_tcon() and DFS cache refresher. Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com> Cc: stable@vger.kernel.org # 6.2 Signed-off-by: Steve French <stfrench@microsoft.com>
232 lines
5.4 KiB
C
232 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Contains the CIFS DFS referral mounting routines used for handling
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* traversal via DFS junction point
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*
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* Copyright (c) 2007 Igor Mammedov
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* Copyright (C) International Business Machines Corp., 2008
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* Author(s): Igor Mammedov (niallain@gmail.com)
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* Steve French (sfrench@us.ibm.com)
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*/
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#include <linux/dcache.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/slab.h>
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#include <linux/vfs.h>
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#include <linux/fs.h>
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#include <linux/inet.h>
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifsfs.h"
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#include "dns_resolve.h"
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#include "cifs_debug.h"
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#include "dfs.h"
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#include "fs_context.h"
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static LIST_HEAD(cifs_dfs_automount_list);
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static void cifs_dfs_expire_automounts(struct work_struct *work);
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static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
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cifs_dfs_expire_automounts);
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static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
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static void cifs_dfs_expire_automounts(struct work_struct *work)
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{
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struct list_head *list = &cifs_dfs_automount_list;
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mark_mounts_for_expiry(list);
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if (!list_empty(list))
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schedule_delayed_work(&cifs_dfs_automount_task,
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cifs_dfs_mountpoint_expiry_timeout);
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}
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void cifs_dfs_release_automount_timer(void)
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{
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BUG_ON(!list_empty(&cifs_dfs_automount_list));
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cancel_delayed_work_sync(&cifs_dfs_automount_task);
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}
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/**
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* cifs_build_devname - build a devicename from a UNC and optional prepath
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* @nodename: pointer to UNC string
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* @prepath: pointer to prefixpath (or NULL if there isn't one)
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*
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* Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
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* big enough to hold the final thing. Copy the UNC from the nodename, and
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* concatenate the prepath onto the end of it if there is one.
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*
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* Returns pointer to the built string, or a ERR_PTR. Caller is responsible
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* for freeing the returned string.
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*/
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char *
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cifs_build_devname(char *nodename, const char *prepath)
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{
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size_t pplen;
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size_t unclen;
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char *dev;
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char *pos;
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/* skip over any preceding delimiters */
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nodename += strspn(nodename, "\\");
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if (!*nodename)
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return ERR_PTR(-EINVAL);
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/* get length of UNC and set pos to last char */
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unclen = strlen(nodename);
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pos = nodename + unclen - 1;
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/* trim off any trailing delimiters */
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while (*pos == '\\') {
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--pos;
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--unclen;
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}
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/* allocate a buffer:
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* +2 for preceding "//"
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* +1 for delimiter between UNC and prepath
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* +1 for trailing NULL
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*/
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pplen = prepath ? strlen(prepath) : 0;
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dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
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if (!dev)
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return ERR_PTR(-ENOMEM);
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pos = dev;
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/* add the initial "//" */
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*pos = '/';
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++pos;
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*pos = '/';
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++pos;
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/* copy in the UNC portion from referral */
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memcpy(pos, nodename, unclen);
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pos += unclen;
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/* copy the prefixpath remainder (if there is one) */
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if (pplen) {
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*pos = '/';
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++pos;
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memcpy(pos, prepath, pplen);
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pos += pplen;
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}
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/* NULL terminator */
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*pos = '\0';
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convert_delimiter(dev, '/');
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return dev;
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}
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static int set_dest_addr(struct smb3_fs_context *ctx, const char *full_path)
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{
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struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
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int rc;
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rc = dns_resolve_server_name_to_ip(full_path, addr, NULL);
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if (!rc)
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cifs_set_port(addr, ctx->port);
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return rc;
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}
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/*
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* Create a vfsmount that we can automount
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*/
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static struct vfsmount *cifs_dfs_do_automount(struct path *path)
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{
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int rc;
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struct dentry *mntpt = path->dentry;
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struct fs_context *fc;
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struct cifs_sb_info *cifs_sb;
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void *page = NULL;
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struct smb3_fs_context *ctx, *cur_ctx;
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struct smb3_fs_context tmp;
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char *full_path;
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struct vfsmount *mnt;
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if (IS_ROOT(mntpt))
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return ERR_PTR(-ESTALE);
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/*
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* The MSDFS spec states that paths in DFS referral requests and
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* responses must be prefixed by a single '\' character instead of
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* the double backslashes usually used in the UNC. This function
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* gives us the latter, so we must adjust the result.
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*/
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cifs_sb = CIFS_SB(mntpt->d_sb);
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if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
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return ERR_PTR(-EREMOTE);
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cur_ctx = cifs_sb->ctx;
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fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, mntpt);
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if (IS_ERR(fc))
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return ERR_CAST(fc);
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ctx = smb3_fc2context(fc);
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page = alloc_dentry_path();
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full_path = dfs_get_automount_devname(mntpt, page);
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if (IS_ERR(full_path)) {
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mnt = ERR_CAST(full_path);
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goto out;
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}
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convert_delimiter(full_path, '/');
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cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
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tmp = *cur_ctx;
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tmp.source = full_path;
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tmp.leaf_fullpath = NULL;
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tmp.UNC = tmp.prepath = NULL;
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tmp.dfs_root_ses = NULL;
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rc = smb3_fs_context_dup(ctx, &tmp);
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if (rc) {
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mnt = ERR_PTR(rc);
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goto out;
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}
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rc = set_dest_addr(ctx, full_path);
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if (rc) {
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mnt = ERR_PTR(rc);
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goto out;
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}
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rc = smb3_parse_devname(full_path, ctx);
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if (!rc)
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mnt = fc_mount(fc);
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else
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mnt = ERR_PTR(rc);
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out:
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put_fs_context(fc);
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free_dentry_path(page);
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return mnt;
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}
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/*
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* Attempt to automount the referral
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*/
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struct vfsmount *cifs_dfs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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cifs_dbg(FYI, "%s: %pd\n", __func__, path->dentry);
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newmnt = cifs_dfs_do_automount(path);
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if (IS_ERR(newmnt)) {
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cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
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return newmnt;
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}
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
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schedule_delayed_work(&cifs_dfs_automount_task,
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cifs_dfs_mountpoint_expiry_timeout);
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cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
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return newmnt;
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}
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const struct inode_operations cifs_dfs_referral_inode_operations = {
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};
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