Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933034Ab3CLPmi (ORCPT ); Tue, 12 Mar 2013 11:42:38 -0400 Received: from mail-bk0-f52.google.com ([209.85.214.52]:48950 "EHLO mail-bk0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932934Ab3CLPmb (ORCPT ); Tue, 12 Mar 2013 11:42:31 -0400 From: Miklos Szeredi To: viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, akpm@linux-foundation.org, apw@canonical.com, nbd@openwrt.org, neilb@suse.de, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, dhowells@redhat.com, sedat.dilek@googlemail.com, hooanon05@yahoo.co.jp, mszeredi@suse.cz Subject: [PATCH 05/13] overlayfs-add-statfs-support Date: Tue, 12 Mar 2013 16:41:40 +0100 Message-Id: <1363102908-28956-6-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1363102908-28956-1-git-send-email-miklos@szeredi.hu> References: <1363102908-28956-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3546 Lines: 116 From: Andy Whitcroft Add support for statfs to the overlayfs filesystem. As the upper layer is the target of all write operations assume that the space in that filesystem is the space in the overlayfs. There will be some inaccuracy as overwriting a file will copy it up and consume space we were not expecting, but it is better than nothing. Use the upper layer dentry and mount from the overlayfs root inode, passing the statfs call to that filesystem. Signed-off-by: Andy Whitcroft Signed-off-by: Miklos Szeredi --- fs/overlayfs/super.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 02deecd..928b1b1 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -17,15 +17,19 @@ #include #include #include +#include #include "overlayfs.h" MODULE_AUTHOR("Miklos Szeredi "); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); +#define OVERLAYFS_SUPER_MAGIC 0x794c764f + struct ovl_fs { struct vfsmount *upper_mnt; struct vfsmount *lower_mnt; + long lower_namelen; }; struct ovl_entry { @@ -406,9 +410,36 @@ static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data) return mnt_want_write(ufs->upper_mnt); } +/** + * ovl_statfs + * @sb: The overlayfs super block + * @buf: The struct kstatfs to fill in with stats + * + * Get the filesystem statistics. As writes always target the upper layer + * filesystem pass the statfs to the same filesystem. + */ +static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + struct ovl_fs *ofs = dentry->d_sb->s_fs_info; + struct dentry *root_dentry = dentry->d_sb->s_root; + struct path path; + int err; + + ovl_path_upper(root_dentry, &path); + + err = vfs_statfs(&path, buf); + if (!err) { + buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); + buf->f_type = OVERLAYFS_SUPER_MAGIC; + } + + return err; +} + static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, .remount_fs = ovl_remount_fs, + .statfs = ovl_statfs, }; struct ovl_config { @@ -474,6 +505,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) struct ovl_entry *oe; struct ovl_fs *ufs; struct ovl_config config; + struct kstatfs statfs; int err; err = ovl_parse_opt((char *) data, &config); @@ -508,6 +540,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) !S_ISDIR(lowerpath.dentry->d_inode->i_mode)) goto out_put_lowerpath; + err = vfs_statfs(&lowerpath, &statfs); + if (err) { + printk(KERN_ERR "overlayfs: statfs failed on lowerpath\n"); + goto out_put_lowerpath; + } + ufs->lower_namelen = statfs.f_namelen; + ufs->upper_mnt = clone_private_mount(&upperpath); err = PTR_ERR(ufs->upper_mnt); if (IS_ERR(ufs->upper_mnt)) { @@ -556,6 +595,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) root_dentry->d_fsdata = oe; root_dentry->d_op = &ovl_dentry_operations; + sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_op = &ovl_super_operations; sb->s_root = root_dentry; sb->s_fs_info = ufs; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/