From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755518Ab2HOPtn (ORCPT ); Wed, 15 Aug 2012 11:49:43 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:50392 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755474Ab2HOPr0 (ORCPT ); Wed, 15 Aug 2012 11:47:26 -0400 From: Miklos Szeredi To: viro@ZenIV.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, apw@canonical.com, nbd@openwrt.org, neilb@suse.de, hramrach@centrum.cz, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, ricwheeler@gmail.com, dhowells@redhat.com, hpj@urpla.net, sedat.dilek@googlemail.com, penberg@kernel.org, goran.cetusic@gmail.com, romain@orebokech.com, mszeredi@suse.cz, Erez Zadok Subject: [PATCH 06/13] overlayfs: implement show_options Date: Wed, 15 Aug 2012 17:48:13 +0200 Message-Id: <1345045700-9062-7-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 1.7.7 In-Reply-To: <1345045700-9062-1-git-send-email-miklos@szeredi.hu> References: <1345045700-9062-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Erez Zadok This is useful because of the stacking nature of overlayfs. Users like to find out (via /proc/mounts) which lower/upper directory were used at mount time. Signed-off-by: Erez Zadok Signed-off-by: Miklos Szeredi --- fs/overlayfs/super.c | 63 ++++++++++++++++++++++++++++++++++---------------- 1 files changed, 43 insertions(+), 20 deletions(-) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 484753b..69a2099 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -17,17 +17,27 @@ #include #include #include +#include #include "overlayfs.h" MODULE_AUTHOR("Miklos Szeredi "); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); +struct ovl_config { + char *lowerdir; + char *upperdir; +}; + +/* private information held for overlayfs's superblock */ struct ovl_fs { struct vfsmount *upper_mnt; struct vfsmount *lower_mnt; + /* pathnames of lower and upper dirs, for show_options */ + struct ovl_config config; }; +/* private information held for every overlayfs dentry */ struct ovl_entry { /* * Keep "double reference" on upper dentries, so that @@ -384,6 +394,8 @@ static void ovl_put_super(struct super_block *sb) mntput(ufs->upper_mnt); mntput(ufs->lower_mnt); + kfree(ufs->config.lowerdir); + kfree(ufs->config.upperdir); kfree(ufs); } @@ -425,15 +437,27 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) return path.dentry->d_sb->s_op->statfs(path.dentry, buf); } +/** + * ovl_show_options + * + * Prints the mount options for a given superblock. + * Returns zero; does not fail. + */ +static int ovl_show_options(struct seq_file *m, struct dentry *dentry) +{ + struct super_block *sb = dentry->d_sb; + struct ovl_fs *ufs = sb->s_fs_info; + + seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir); + seq_printf(m, ",upperdir=%s", ufs->config.upperdir); + return 0; +} + static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, .remount_fs = ovl_remount_fs, .statfs = ovl_statfs, -}; - -struct ovl_config { - char *lowerdir; - char *upperdir; + .show_options = ovl_show_options, }; enum { @@ -493,33 +517,32 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_fs *ufs; - struct ovl_config config; int err; - err = ovl_parse_opt((char *) data, &config); - if (err) + err = -ENOMEM; + ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); + if (!ufs) goto out; + err = ovl_parse_opt((char *) data, &ufs->config); + if (err) + goto out_free_ufs; + err = -EINVAL; - if (!config.upperdir || !config.lowerdir) { + if (!ufs->config.upperdir || !ufs->config.lowerdir) { printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n"); goto out_free_config; } - err = -ENOMEM; - ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); - if (!ufs) - goto out_free_config; - oe = ovl_alloc_entry(); if (oe == NULL) - goto out_free_ufs; + goto out_free_config; - err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath); + err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath); if (err) goto out_free_oe; - err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath); + err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath); if (err) goto out_put_upperpath; @@ -595,11 +618,11 @@ out_put_upperpath: path_put(&upperpath); out_free_oe: kfree(oe); +out_free_config: + kfree(ufs->config.lowerdir); + kfree(ufs->config.upperdir); out_free_ufs: kfree(ufs); -out_free_config: - kfree(config.lowerdir); - kfree(config.upperdir); out: return err; } -- 1.7.7