From mboxrd@z Thu Jan 1 00:00:00 1970 From: hujianyang Subject: [PATCH 3/3] ovl: upper fs should not be R/O Date: Thu, 15 Jan 2015 13:20:57 +0800 Message-ID: <54B74E39.8080405@huawei.com> References: <54B74D70.3000205@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from szxga01-in.huawei.com ([119.145.14.64]:29892 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031AbbAOFVN (ORCPT ); Thu, 15 Jan 2015 00:21:13 -0500 In-Reply-To: <54B74D70.3000205@huawei.com> Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org To: Miklos Szeredi Cc: linux-unionfs@vger.kernel.org, "linux-fsdevel@vger.kernel.org" , Seunghun Lee , Fabian Sturm After importing multi-lower layer support, users could mount a r/o partition as the left most lowerdir instead of using it as upperdir. And a r/o upperdir may cause an error like overlayfs: failed to create directory ./workdir/work during mount. This patch check the *s_flags* of upper fs and return an error if it is a r/o partition. The checking of *upper_mnt->mnt_sb->s_flags* can be removed now. This patch also remove /* FIXME: workdir is not needed for a R/O mount */ from ovl_fill_super() because: 1) for upper fs r/o case Setting a r/o partition as upper is prevented, no need to care about workdir in this case. 2) for "mount overlay -o ro" with a r/w upper fs case Users could remount overlayfs to r/w in this case, so workdir should not be omitted. Signed-off-by: hujianyang --- fs/overlayfs/super.c | 24 +++++++++++++++++++----- 1 files changed, 19 insertions(+), 5 deletions(-) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index edbb3eb..0e7a477 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -529,8 +529,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data) { struct ovl_fs *ufs = sb->s_fs_info; - if (!(*flags & MS_RDONLY) && - (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))) + if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt)) return -EROFS; return 0; @@ -619,6 +618,15 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) return -EINVAL; } } + + /* Workdir is useless in non-upper mount */ + if (!config->upperdir && config->workdir) { + pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", + config->workdir); + kfree(config->workdir); + config->workdir = NULL; + } + return 0; } @@ -838,7 +846,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) sb->s_stack_depth = 0; if (ufs->config.upperdir) { - /* FIXME: workdir is not needed for a R/O mount */ if (!ufs->config.workdir) { pr_err("overlayfs: missing 'workdir'\n"); goto out_free_config; @@ -848,6 +855,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (err) goto out_free_config; + /* Upper fs should not be r/o */ + if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { + pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); + err = -EINVAL; + goto out_put_upperpath; + } + err = ovl_mount_dir(ufs->config.workdir, &workpath); if (err) goto out_put_upperpath; @@ -939,8 +953,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ufs->numlower++; } - /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */ - if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)) + /* If the upper fs is nonexistent, we mark overlayfs r/o too */ + if (!ufs->upper_mnt) sb->s_flags |= MS_RDONLY; sb->s_d_op = &ovl_dentry_operations; -- 1.6.0.2 From mboxrd@z Thu Jan 1 00:00:00 1970 From: hujianyang Subject: [PATCH 3/3] ovl: upper fs should not be R/O Date: Thu, 15 Jan 2015 13:20:57 +0800 Message-ID: <54B74E39.8080405@huawei.com> References: <54B74D70.3000205@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , "linux-fsdevel@vger.kernel.org" , Seunghun Lee , "Fabian Sturm" To: Miklos Szeredi Return-path: In-Reply-To: <54B74D70.3000205@huawei.com> Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org After importing multi-lower layer support, users could mount a r/o partition as the left most lowerdir instead of using it as upperdir. And a r/o upperdir may cause an error like overlayfs: failed to create directory ./workdir/work during mount. This patch check the *s_flags* of upper fs and return an error if it is a r/o partition. The checking of *upper_mnt->mnt_sb->s_flags* can be removed now. This patch also remove /* FIXME: workdir is not needed for a R/O mount */ from ovl_fill_super() because: 1) for upper fs r/o case Setting a r/o partition as upper is prevented, no need to care about workdir in this case. 2) for "mount overlay -o ro" with a r/w upper fs case Users could remount overlayfs to r/w in this case, so workdir should not be omitted. Signed-off-by: hujianyang --- fs/overlayfs/super.c | 24 +++++++++++++++++++----- 1 files changed, 19 insertions(+), 5 deletions(-) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index edbb3eb..0e7a477 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -529,8 +529,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data) { struct ovl_fs *ufs = sb->s_fs_info; - if (!(*flags & MS_RDONLY) && - (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))) + if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt)) return -EROFS; return 0; @@ -619,6 +618,15 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) return -EINVAL; } } + + /* Workdir is useless in non-upper mount */ + if (!config->upperdir && config->workdir) { + pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", + config->workdir); + kfree(config->workdir); + config->workdir = NULL; + } + return 0; } @@ -838,7 +846,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) sb->s_stack_depth = 0; if (ufs->config.upperdir) { - /* FIXME: workdir is not needed for a R/O mount */ if (!ufs->config.workdir) { pr_err("overlayfs: missing 'workdir'\n"); goto out_free_config; @@ -848,6 +855,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (err) goto out_free_config; + /* Upper fs should not be r/o */ + if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { + pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); + err = -EINVAL; + goto out_put_upperpath; + } + err = ovl_mount_dir(ufs->config.workdir, &workpath); if (err) goto out_put_upperpath; @@ -939,8 +953,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ufs->numlower++; } - /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */ - if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)) + /* If the upper fs is nonexistent, we mark overlayfs r/o too */ + if (!ufs->upper_mnt) sb->s_flags |= MS_RDONLY; sb->s_d_op = &ovl_dentry_operations; -- 1.6.0.2