From patchwork Thu Feb 6 15:24:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josef Bacik X-Patchwork-Id: 11368823 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D241109A for ; Thu, 6 Feb 2020 15:24:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED61722464 for ; Thu, 6 Feb 2020 15:24:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="I3GlkDtu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727787AbgBFPYd (ORCPT ); Thu, 6 Feb 2020 10:24:33 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:46731 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727771AbgBFPYd (ORCPT ); Thu, 6 Feb 2020 10:24:33 -0500 Received: by mail-qt1-f194.google.com with SMTP id e25so4726079qtr.13 for ; Thu, 06 Feb 2020 07:24:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=wCE1OrUi7dG/tAWTXpeobeYMsWGCcBI76eOyzL2rKGY=; b=I3GlkDtuURhAn9l/gc6GUiNrDblKCJTrGzpzFnGtdWKWWPqNf2L0RUPD9Pu8TwP8jb yHD0EgHomB9395/YsoeFBRAIvs4OPr+WedRONfpRXQM4ogKgQZNG1cnxqtYkLCDgavkV Au+W87+Jq/AN8vCJAFtKTuDIYOuRfECoTf4tSXuyvHcw33i+ETqYuyxzs9TCqzryc4// FPs7hoJoG/aZtfL8z3GJs0L+gHiTbiZclPA9+O+/Wojko2DgJyytPlxvT7j4h2LqNawy Js3Xgi3cUsaWZLp/p1mVUR3cVmR14sbdRabl7BA69/dQKCFarMZCnsFvAdy/GaD7vaNi /pnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=wCE1OrUi7dG/tAWTXpeobeYMsWGCcBI76eOyzL2rKGY=; b=bNtCqq0oOnE03xoC4+2J2XVB5v9DYgjp1G/RGLEldun0s7ZFhO+ruJKAKrxkFaarPt vrlXMi0NBwFeUCLo+UlVLSbJCWXSF6YWBFmL9a+xBB01NKt8MiVRa8f/Egsq6AS8IO2+ IutCSSg+g3iFCXdJXA/htxYyDWZsejlmcrluoPZUVJ/xMHFygyX6426faCoWcZb82Vkj TXl6OBR2hBjMjVJq25K9kXkRX3Qsn7FXDzZESIm1OuOIRg6TvgyuuQ95yKGUnf2zA6qm ynT5TL8RCpexxdPGV0ntBYgtlGZ89Iut9KYMM2VEIIOJs/zVd/SIK8p4DUmIt9b4wFRL OU0w== X-Gm-Message-State: APjAAAUla8b279iPNwdmGFwBj9vU+X18WRTDfr7uIkBEznzTlPkIwSes lS4g21IB6IHZgmHaqkw8NAn/rEXaqxQ= X-Google-Smtp-Source: APXvYqxexH2/JbbfX9CczM6Xnt2YTnRtQMxFuTjohg6rcYLPOxAIbWwE5W6J+RxFU6jDiEucYbVKbg== X-Received: by 2002:ac8:584:: with SMTP id a4mr3149830qth.240.1581002671363; Thu, 06 Feb 2020 07:24:31 -0800 (PST) Received: from localhost ([107.15.81.208]) by smtp.gmail.com with ESMTPSA id q73sm1559258qka.56.2020.02.06.07.24.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 07:24:30 -0800 (PST) From: Josef Bacik To: linux-btrfs@vger.kernel.org, kernel-team@fb.com, dsterba@suse.cz Subject: [PATCH][v2] btrfs: hold a ref on the root in get_subvol_name_from_objectid Date: Thu, 6 Feb 2020 10:24:26 -0500 Message-Id: <20200206152426.6312-1-josef@toxicpanda.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200205151902.GS2654@twin.jikos.cz> References: <20200205151902.GS2654@twin.jikos.cz> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org We lookup the name of a subvol which means we'll cross into different roots. Hold a ref while we're doing the look ups in the fs_root we're searching. Signed-off-by: Josef Bacik --- v1->v2: - Moved the btrfs_put_fs_root() to err, but this requires making sure that fs_root == NULL in all the cases we won't have a valid fs_root to drop a ref on. fs/btrfs/super.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index fa74caf39165..96bc10da5ff2 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1028,7 +1028,7 @@ static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, u64 subvol_objectid) { struct btrfs_root *root = fs_info->tree_root; - struct btrfs_root *fs_root; + struct btrfs_root *fs_root = NULL; struct btrfs_root_ref *root_ref; struct btrfs_inode_ref *inode_ref; struct btrfs_key key; @@ -1099,6 +1099,12 @@ static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, fs_root = btrfs_get_fs_root(fs_info, &key, true); if (IS_ERR(fs_root)) { ret = PTR_ERR(fs_root); + fs_root = NULL; + goto err; + } + if (!btrfs_grab_fs_root(fs_root)) { + ret = -ENOENT; + fs_root = NULL; goto err; } @@ -1143,6 +1149,8 @@ static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, ptr[0] = '/'; btrfs_release_path(path); } + btrfs_put_fs_root(fs_root); + fs_root = NULL; } btrfs_free_path(path); @@ -1155,6 +1163,7 @@ static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, return name; err: + btrfs_put_fs_root(fs_root); btrfs_free_path(path); kfree(name); return ERR_PTR(ret);