1 files changed, 40 insertions, 91 deletions

diff --git a/fs/cifs/dfs.c b/fs/smb/client/dfs.c
index a93dbca1411b..df3fd3b720da 100644
--- a/fs/cifs/dfs.c
+++ b/fs/smb/client/dfs.c
@@ -54,39 +54,6 @@ out:
 	return rc;
 }
 
-/*
- * cifs_build_path_to_root returns full path to root when we do not have an
- * existing connection (tcon)
- */
-static char *build_unc_path_to_root(const struct smb3_fs_context *ctx,
-				    const struct cifs_sb_info *cifs_sb, bool useppath)
-{
-	char *full_path, *pos;
-	unsigned int pplen = useppath && ctx->prepath ? strlen(ctx->prepath) + 1 : 0;
-	unsigned int unc_len = strnlen(ctx->UNC, MAX_TREE_SIZE + 1);
-
-	if (unc_len > MAX_TREE_SIZE)
-		return ERR_PTR(-EINVAL);
-
-	full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
-	if (full_path == NULL)
-		return ERR_PTR(-ENOMEM);
-
-	memcpy(full_path, ctx->UNC, unc_len);
-	pos = full_path + unc_len;
-
-	if (pplen) {
-		*pos = CIFS_DIR_SEP(cifs_sb);
-		memcpy(pos + 1, ctx->prepath, pplen);
-		pos += pplen;
-	}
-
-	*pos = '\0'; /* add trailing null */
-	convert_delimiter(full_path, CIFS_DIR_SEP(cifs_sb));
-	cifs_dbg(FYI, "%s: full_path=%s\n", __func__, full_path);
-	return full_path;
-}
-
 static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path)
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
@@ -99,6 +66,12 @@ static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path)
 	return rc;
 }
 
+/*
+ * Track individual DFS referral servers used by new DFS mount.
+ *
+ * On success, their lifetime will be shared by final tcon (dfs_ses_list).
+ * Otherwise, they will be put by dfs_put_root_smb_sessions() in cifs_mount().
+ */
 static int add_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
@@ -113,11 +86,12 @@ static int add_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
 		INIT_LIST_HEAD(&root_ses->list);
 
 		spin_lock(&cifs_tcp_ses_lock);
-		ses->ses_count++;
+		cifs_smb_ses_inc_refcount(ses);
 		spin_unlock(&cifs_tcp_ses_lock);
 		root_ses->ses = ses;
 		list_add_tail(&root_ses->list, &mnt_ctx->dfs_ses_list);
 	}
+	/* Select new DFS referral server so that new referrals go through it */
 	ctx->dfs_root_ses = ses;
 	return 0;
 }
@@ -176,9 +150,9 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
 	char *ref_path = NULL, *full_path = NULL;
 	struct dfs_cache_tgt_iterator *tit;
-	struct TCP_Server_Info *server;
 	struct cifs_tcon *tcon;
 	char *origin_fullpath = NULL;
+	char sep = CIFS_DIR_SEP(cifs_sb);
 	int num_links = 0;
 	int rc;
 
@@ -186,7 +160,7 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 	if (IS_ERR(ref_path))
 		return PTR_ERR(ref_path);
 
-	full_path = build_unc_path_to_root(ctx, cifs_sb, true);
+	full_path = smb3_fs_context_fullpath(ctx, sep);
 	if (IS_ERR(full_path)) {
 		rc = PTR_ERR(full_path);
 		full_path = NULL;
@@ -228,7 +202,7 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 				kfree(full_path);
 				ref_path = full_path = NULL;
 
-				full_path = build_unc_path_to_root(ctx, cifs_sb, true);
+				full_path = smb3_fs_context_fullpath(ctx, sep);
 				if (IS_ERR(full_path)) {
 					rc = PTR_ERR(full_path);
 					full_path = NULL;
@@ -246,17 +220,14 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 	} while (rc == -EREMOTE);
 
 	if (!rc) {
-		server = mnt_ctx->server;
 		tcon = mnt_ctx->tcon;
 
-		mutex_lock(&server->refpath_lock);
-		spin_lock(&server->srv_lock);
-		if (!server->origin_fullpath) {
-			server->origin_fullpath = origin_fullpath;
+		spin_lock(&tcon->tc_lock);
+		if (!tcon->origin_fullpath) {
+			tcon->origin_fullpath = origin_fullpath;
 			origin_fullpath = NULL;
 		}
-		spin_unlock(&server->srv_lock);
-		mutex_unlock(&server->refpath_lock);
+		spin_unlock(&tcon->tc_lock);
 
 		if (list_empty(&tcon->dfs_ses_list)) {
 			list_replace_init(&mnt_ctx->dfs_ses_list,
@@ -278,19 +249,13 @@ out:
 int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
-	struct cifs_ses *ses;
-	char *source = ctx->source;
 	bool nodfs = ctx->nodfs;
 	int rc;
 
 	*isdfs = false;
-	/* Temporarily set @ctx->source to NULL as we're not matching DFS
-	 * superblocks yet.  See cifs_match_super() and match_server().
-	 */
-	ctx->source = NULL;
 	rc = get_session(mnt_ctx, NULL);
 	if (rc)
-		goto out;
+		return rc;
 
 	ctx->dfs_root_ses = mnt_ctx->ses;
 	/*
@@ -303,8 +268,9 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 	if (!nodfs) {
 		rc = dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL);
 		if (rc) {
-			if (rc != -ENOENT && rc != -EOPNOTSUPP)
-				goto out;
+			cifs_dbg(FYI, "%s: no dfs referral for %s: %d\n",
+				 __func__, ctx->UNC + 1, rc);
+			cifs_dbg(FYI, "%s: assuming non-dfs mount...\n", __func__);
 			nodfs = true;
 		}
 	}
@@ -312,29 +278,12 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 		rc = cifs_mount_get_tcon(mnt_ctx);
 		if (!rc)
 			rc = cifs_is_path_remote(mnt_ctx);
-		goto out;
+		return rc;
 	}
 
 	*isdfs = true;
-	/*
-	 * Prevent DFS root session of being put in the first call to
-	 * cifs_mount_put_conns().  If another DFS root server was not found
-	 * while chasing the referrals (@ctx->dfs_root_ses == @ses), then we
-	 * can safely put extra refcount of @ses.
-	 */
-	ses = mnt_ctx->ses;
-	mnt_ctx->ses = NULL;
-	mnt_ctx->server = NULL;
-	rc = __dfs_mount_share(mnt_ctx);
-	if (ses == ctx->dfs_root_ses)
-		cifs_put_smb_ses(ses);
-out:
-	/*
-	 * Restore previous value of @ctx->source so DFS superblock can be
-	 * matched in cifs_match_super().
-	 */
-	ctx->source = source;
-	return rc;
+	add_root_smb_session(mnt_ctx);
+	return __dfs_mount_share(mnt_ctx);
 }
 
 /* Update dfs referral path of superblock */
@@ -567,24 +516,25 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
 	int rc;
 	struct TCP_Server_Info *server = tcon->ses->server;
 	const struct smb_version_operations *ops = server->ops;
-	struct super_block *sb = NULL;
-	struct cifs_sb_info *cifs_sb;
 	struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
-	char *tree;
+	struct cifs_sb_info *cifs_sb = NULL;
+	struct super_block *sb = NULL;
 	struct dfs_info3_param ref = {0};
+	char *tree;
 
 	/* only send once per connect */
 	spin_lock(&tcon->tc_lock);
+	if (tcon->status == TID_GOOD) {
+		spin_unlock(&tcon->tc_lock);
+		return 0;
+	}
+
 	if (tcon->status != TID_NEW &&
 	    tcon->status != TID_NEED_TCON) {
 		spin_unlock(&tcon->tc_lock);
 		return -EHOSTDOWN;
 	}
 
-	if (tcon->status == TID_GOOD) {
-		spin_unlock(&tcon->tc_lock);
-		return 0;
-	}
 	tcon->status = TID_IN_TCON;
 	spin_unlock(&tcon->tc_lock);
 
@@ -602,19 +552,18 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
 		goto out;
 	}
 
-	sb = cifs_get_tcp_super(server);
-	if (IS_ERR(sb)) {
-		rc = PTR_ERR(sb);
-		cifs_dbg(VFS, "%s: could not find superblock: %d\n", __func__, rc);
-		goto out;
-	}
-
-	cifs_sb = CIFS_SB(sb);
+	sb = cifs_get_dfs_tcon_super(tcon);
+	if (!IS_ERR(sb))
+		cifs_sb = CIFS_SB(sb);
 
-	/* If it is not dfs or there was no cached dfs referral, then reconnect to same share */
-	if (!server->leaf_fullpath ||
+	/*
+	 * Tree connect to last share in @tcon->tree_name whether dfs super or
+	 * cached dfs referral was not found.
+	 */
+	if (!cifs_sb || !server->leaf_fullpath ||
 	    dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) {
-		rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
+		rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon,
+				       cifs_sb ? cifs_sb->local_nls : nlsc);
 		goto out;
 	}