linux-kernel - [RFC][PATCH 2/3] vfs: Add a function to lazily unmount all mounts from any dentry.

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Message-ID: <87a9io1wu1.fsf_-_@xmission.com>
Date:	Fri, 04 Oct 2013 15:43:18 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	"Serge E. Hallyn" <serge@...lyn.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Rob Landley <rob@...dley.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC][PATCH 2/3] vfs: Add a function to lazily unmount all mounts from any dentry.


Signed-off-by: Eric W. Biederman <ebiederman@...tter.com>
---
 fs/mount.h     |    1 +
 fs/namespace.c |   24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/fs/mount.h b/fs/mount.h
index e4342b8dfab1..7a6a2bb3f290 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -79,6 +79,7 @@ static inline int is_mounted(struct vfsmount *mnt)
 }
 
 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
+extern void detach_mounts(struct dentry *dentry);
 
 static inline void get_mnt_ns(struct mnt_namespace *ns)
 {
diff --git a/fs/namespace.c b/fs/namespace.c
index d092964fe7f9..8eaee0c14fdb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1294,6 +1294,30 @@ static int do_umount(struct mount *mnt, int flags)
 	return retval;
 }
 
+void detach_mounts(struct dentry *dentry)
+{
+	struct mount *mnt, *next;
+	struct mountpoint *mp;
+
+	namespace_lock();
+	if (!d_mountpoint(dentry)) {
+		namespace_unlock();
+		return;
+	}
+	mp = new_mountpoint(dentry);
+	if (IS_ERR(mp)) {
+		return;
+	}
+	br_write_lock(&vfsmount_lock);
+	list_for_each_entry_safe(mnt, next, &mp->m_list, mnt_mp_list) {
+		if (!list_empty(&mnt->mnt_list))
+			umount_tree(mnt, 1);
+	}
+	br_write_unlock(&vfsmount_lock);
+	put_mountpoint(mp);
+	namespace_unlock();
+}
+
 /* 
  * Is the caller allowed to modify his namespace?
  */
-- 
1.7.5.4

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