cifs: Extract DFS referral expansion logic to separate function

The logic behind the expansion of DFS referrals is now extracted from
cifs_mount into a new static function, expand_dfs_referral.  This will
reduce duplicate code in upcoming commits.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Sean Finney <seanius@seanius.net>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 69 insertions, 36 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 2b511991187..b6c6a3629b0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2745,6 +2745,57 @@ build_unc_path_to_root(const struct smb_vol *volume_info,
         full_path[unc_len + cifs_sb->prepathlen] = 0; /* add trailing null */
         return full_path;
 }
+
+/*
+ * Perform a dfs referral query for a share and (optionally) prefix
+ *
+ * If a referral is found, mount_data will be set to point at a newly
+ * allocated string containing updated options for the submount.
+ * Otherwise it will be left untouched.
+ *
+ * Returns the rc from get_dfs_path to the caller, which can be used to
+ * determine whether there were referrals.
+ */
+static int
+expand_dfs_referral(int xid, struct cifsSesInfo *pSesInfo,
+                    struct smb_vol *volume_info, struct cifs_sb_info *cifs_sb,
+                    char **mount_data, int check_prefix)
+{
+        int rc;
+        unsigned int num_referrals = 0;
+        struct dfs_info3_param *referrals = NULL;
+        char *full_path = NULL, *ref_path = NULL, *mdata = NULL;
+
+        full_path = build_unc_path_to_root(volume_info, cifs_sb);
+        if (IS_ERR(full_path))
+                return PTR_ERR(full_path);
+
+        /* For DFS paths, skip the first '\' of the UNC */
+        ref_path = check_prefix ? full_path + 1 : volume_info->UNC + 1;
+
+        rc = get_dfs_path(xid, pSesInfo , ref_path, cifs_sb->local_nls,
+                          &num_referrals, &referrals,
+                          cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+
+        if (!rc && num_referrals > 0) {
+                char *fake_devname = NULL;
+
+                mdata = cifs_compose_mount_options(cifs_sb->mountdata,
+                                                   full_path + 1, referrals,
+                                                   &fake_devname);
+
+                free_dfs_info_array(referrals, num_referrals);
+                kfree(fake_devname);
+
+                if (IS_ERR(mdata)) {
+                        rc = PTR_ERR(mdata);
+                        mdata = NULL;
+                }
+                *mount_data = mdata;
+        }
+        kfree(full_path);
+        return rc;
+}
 #endif
 
 int
@@ -2761,10 +2812,19 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
         char *mount_data = mount_data_global;
         struct tcon_link *tlink;
 #ifdef CONFIG_CIFS_DFS_UPCALL
-        struct dfs_info3_param *referrals = NULL;
-        unsigned int num_referrals = 0;
         int referral_walks_count = 0;
 try_mount_again:
+
+        /* cleanup activities if we're chasing a referral */
+        if (referral_walks_count) {
+                if (tcon)
+                        cifs_put_tcon(tcon);
+                else if (pSesInfo)
+                        cifs_put_smb_ses(pSesInfo);
+
+                cleanup_volume_info(&volume_info);
+                FreeXid(xid);
+        }
 #endif
         rc = 0;
         tcon = NULL;
@@ -2910,46 +2970,19 @@ remote_path_check:
                 if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)
                         convert_delimiter(cifs_sb->prepath,
                                         CIFS_DIR_SEP(cifs_sb));
-                full_path = build_unc_path_to_root(volume_info, cifs_sb);
-                if (IS_ERR(full_path)) {
-                        rc = PTR_ERR(full_path);
-                        goto mount_fail_check;
-                }
 
-                cFYI(1, "Getting referral for: %s", full_path);
-                rc = get_dfs_path(xid, pSesInfo , full_path + 1,
-                        cifs_sb->local_nls, &num_referrals, &referrals,
-                        cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
-                if (!rc && num_referrals > 0) {
-                        char *fake_devname = NULL;
-
-                        if (mount_data != mount_data_global)
-                                kfree(mount_data);
-
-                        mount_data = cifs_compose_mount_options(
-                                        cifs_sb->mountdata, full_path + 1,
-                                        referrals, &fake_devname);
-
-                        free_dfs_info_array(referrals, num_referrals);
-                        kfree(fake_devname);
-                        kfree(full_path);
-
-                        if (IS_ERR(mount_data)) {
-                                rc = PTR_ERR(mount_data);
-                                mount_data = NULL;
-                                goto mount_fail_check;
-                        }
+                if (mount_data != mount_data_global)
+                        kfree(mount_data);
 
-                        if (tcon)
-                                cifs_put_tcon(tcon);
-                        else if (pSesInfo)
-                                cifs_put_smb_ses(pSesInfo);
+                rc = expand_dfs_referral(xid, pSesInfo, volume_info, cifs_sb,
+                                         &mount_data, true);
 
-                        cleanup_volume_info(&volume_info);
+                if (!rc) {
                         referral_walks_count++;
-                        FreeXid(xid);
                         goto try_mount_again;
                 }
+                mount_data = NULL;
+                goto mount_fail_check;
 #else /* No DFS support, return error on mount */
                 rc = -EOPNOTSUPP;
 #endif