linux-kernel - [PATCH 05/13] overlayfs: add statfs support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1345045700-9062-6-git-send-email-miklos@szeredi.hu>
Date:	Wed, 15 Aug 2012 17:48:12 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	viro@...IV.linux.org.uk
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	hch@...radead.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, apw@...onical.com, nbd@...nwrt.org,
	neilb@...e.de, hramrach@...trum.cz, jordipujolp@...il.com,
	ezk@....cs.sunysb.edu, ricwheeler@...il.com, dhowells@...hat.com,
	hpj@...la.net, sedat.dilek@...glemail.com, penberg@...nel.org,
	goran.cetusic@...il.com, romain@...bokech.com, mszeredi@...e.cz
Subject: [PATCH 05/13] overlayfs: add statfs support

From: Andy Whitcroft <apw@...onical.com>

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 <apw@...onical.com>
Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
---
 fs/overlayfs/super.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 02deecd..484753b 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -406,9 +406,29 @@ 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 dentry *root_dentry = dentry->d_sb->s_root;
+	struct path path;
+	ovl_path_upper(root_dentry, &path);
+
+	if (!path.dentry->d_sb->s_op->statfs)
+		return -ENOSYS;
+	return path.dentry->d_sb->s_op->statfs(path.dentry, buf);
+}
+
 static const struct super_operations ovl_super_operations = {
 	.put_super	= ovl_put_super,
 	.remount_fs	= ovl_remount_fs,
+	.statfs		= ovl_statfs,
 };
 
 struct ovl_config {
-- 
1.7.7

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/