From patchwork Wed Apr 8 10:58:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 11479779 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 E51A914B4 for ; Wed, 8 Apr 2020 10:58:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5E7620747 for ; Wed, 8 Apr 2020 10:58:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728371AbgDHK6c (ORCPT ); Wed, 8 Apr 2020 06:58:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:36110 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728207AbgDHK6c (ORCPT ); Wed, 8 Apr 2020 06:58:32 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 1F16FAD57; Wed, 8 Apr 2020 10:58:28 +0000 (UTC) From: Luis Henriques To: Greg Kroah-Hartman , Sasha Levin Cc: Jeff Layton , Ilya Dryomov , ceph-devel@vger.kernel.org, stable@vger.kernel.org, Xiubo Li , Luis Henriques Subject: [PATCH 5.4 1/2] ceph: remove the extra slashes in the server path Date: Wed, 8 Apr 2020 11:58:43 +0100 Message-Id: <20200408105844.21840-6-lhenriques@suse.com> In-Reply-To: <20200408105844.21840-1-lhenriques@suse.com> References: <20200408105844.21840-1-lhenriques@suse.com> MIME-Version: 1.0 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Xiubo Li commit 4fbc0c711b2464ee1551850b85002faae0b775d5 upstream. It's possible to pass the mount helper a server path that has more than one contiguous slash character. For example: $ mount -t ceph 192.168.195.165:40176:/// /mnt/cephfs/ In the MDS server side the extra slashes of the server path will be treated as snap dir, and then we can get the following debug logs: ceph: mount opening path // ceph: open_root_inode opening '//' ceph: fill_trace 0000000059b8a3bc is_dentry 0 is_target 1 ceph: alloc_inode 00000000dc4ca00b ceph: get_inode created new inode 00000000dc4ca00b 1.ffffffffffffffff ino 1 ceph: get_inode on 1=1.ffffffffffffffff got 00000000dc4ca00b And then when creating any new file or directory under the mount point, we can hit the following BUG_ON in ceph_fill_trace(): BUG_ON(ceph_snap(dir) != dvino.snap); Have the client ignore the extra slashes in the server path when mounting. This will also canonicalize the path, so that identical mounts can be consilidated. 1) "//mydir1///mydir//" 2) "/mydir1/mydir" 3) "/mydir1/mydir/" Regardless of the internal treatment of these paths, the kernel still stores the original string including the leading '/' for presentation to userland. URL: https://tracker.ceph.com/issues/42771 Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov Signed-off-by: Luis Henriques --- fs/ceph/super.c | 120 ++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 101 insertions(+), 19 deletions(-) diff --git a/fs/ceph/super.c b/fs/ceph/super.c index 62fc7d46032e..54b50452ec1e 100644 --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -106,7 +106,6 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf) return 0; } - static int ceph_sync_fs(struct super_block *sb, int wait) { struct ceph_fs_client *fsc = ceph_sb_to_client(sb); @@ -430,6 +429,73 @@ static int strcmp_null(const char *s1, const char *s2) return strcmp(s1, s2); } +/** + * path_remove_extra_slash - Remove the extra slashes in the server path + * @server_path: the server path and could be NULL + * + * Return NULL if the path is NULL or only consists of "/", or a string + * without any extra slashes including the leading slash(es) and the + * slash(es) at the end of the server path, such as: + * "//dir1////dir2///" --> "dir1/dir2" + */ +static char *path_remove_extra_slash(const char *server_path) +{ + const char *path = server_path; + const char *cur, *end; + char *buf, *p; + int len; + + /* if the server path is omitted */ + if (!path) + return NULL; + + /* remove all the leading slashes */ + while (*path == '/') + path++; + + /* if the server path only consists of slashes */ + if (*path == '\0') + return NULL; + + len = strlen(path); + + buf = kmalloc(len + 1, GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + end = path + len; + p = buf; + do { + cur = strchr(path, '/'); + if (!cur) + cur = end; + + len = cur - path; + + /* including one '/' */ + if (cur != end) + len += 1; + + memcpy(p, path, len); + p += len; + + while (cur <= end && *cur == '/') + cur++; + path = cur; + } while (path < end); + + *p = '\0'; + + /* + * remove the last slash if there has and just to make sure that + * we will get something like "dir1/dir2" + */ + if (*(--p) == '/') + *p = '\0'; + + return buf; +} + static int compare_mount_options(struct ceph_mount_options *new_fsopt, struct ceph_options *new_opt, struct ceph_fs_client *fsc) @@ -437,6 +503,7 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt, struct ceph_mount_options *fsopt1 = new_fsopt; struct ceph_mount_options *fsopt2 = fsc->mount_options; int ofs = offsetof(struct ceph_mount_options, snapdir_name); + char *p1, *p2; int ret; ret = memcmp(fsopt1, fsopt2, ofs); @@ -449,9 +516,21 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt, ret = strcmp_null(fsopt1->mds_namespace, fsopt2->mds_namespace); if (ret) return ret; - ret = strcmp_null(fsopt1->server_path, fsopt2->server_path); + + p1 = path_remove_extra_slash(fsopt1->server_path); + if (IS_ERR(p1)) + return PTR_ERR(p1); + p2 = path_remove_extra_slash(fsopt2->server_path); + if (IS_ERR(p2)) { + kfree(p1); + return PTR_ERR(p2); + } + ret = strcmp_null(p1, p2); + kfree(p1); + kfree(p2); if (ret) return ret; + ret = strcmp_null(fsopt1->fscache_uniq, fsopt2->fscache_uniq); if (ret) return ret; @@ -507,12 +586,14 @@ static int parse_mount_options(struct ceph_mount_options **pfsopt, */ dev_name_end = strchr(dev_name, '/'); if (dev_name_end) { - if (strlen(dev_name_end) > 1) { - fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL); - if (!fsopt->server_path) { - err = -ENOMEM; - goto out; - } + /* + * The server_path will include the whole chars from userland + * including the leading '/'. + */ + fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL); + if (!fsopt->server_path) { + err = -ENOMEM; + goto out; } } else { dev_name_end = dev_name + strlen(dev_name); @@ -842,7 +923,6 @@ static void destroy_caches(void) ceph_fscache_unregister(); } - /* * ceph_umount_begin - initiate forced umount. Tear down down the * mount, skipping steps that may hang while waiting for server(s). @@ -929,9 +1009,6 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc, return root; } - - - /* * mount: join the ceph cluster, and open root directory. */ @@ -945,7 +1022,7 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc) mutex_lock(&fsc->client->mount_mutex); if (!fsc->sb->s_root) { - const char *path; + const char *path, *p; err = __ceph_open_session(fsc->client, started); if (err < 0) goto out; @@ -957,17 +1034,22 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc) goto out; } - if (!fsc->mount_options->server_path) { - path = ""; - dout("mount opening path \\t\n"); - } else { - path = fsc->mount_options->server_path + 1; - dout("mount opening path %s\n", path); + p = path_remove_extra_slash(fsc->mount_options->server_path); + if (IS_ERR(p)) { + err = PTR_ERR(p); + goto out; } + /* if the server path is omitted or just consists of '/' */ + if (!p) + path = ""; + else + path = p; + dout("mount opening path '%s'\n", path); ceph_fs_debugfs_init(fsc); root = open_root_dentry(fsc, path, started); + kfree(p); if (IS_ERR(root)) { err = PTR_ERR(root); goto out;