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authorIan Kent <ikent@redhat.com>2016-11-24 08:03:41 +1100
committerAl Viro <viro@zeniv.linux.org.uk>2016-12-03 20:51:35 -0500
commitc6609c0a1c34fc097152b28b496236625673924f (patch)
tree864cfb55fd8727e2a475ca44dd8d7df5a8488005 /fs/mount.h
parentfb5f51c7425ebc808d91329257cbc963e2421368 (diff)
downloadlwn-c6609c0a1c34fc097152b28b496236625673924f.tar.gz
lwn-c6609c0a1c34fc097152b28b496236625673924f.zip
vfs: add path_is_mountpoint() helper
d_mountpoint() can only be used reliably to establish if a dentry is not mounted in any namespace. It isn't aware of the possibility there may be multiple mounts using a given dentry that may be in a different namespace. Add helper functions, path_is_mountpoint(), that checks if a struct path is a mountpoint for this case. Link: http://lkml.kernel.org/r/20161011053358.27645.9729.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/mount.h')
-rw-r--r--fs/mount.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/mount.h b/fs/mount.h
index d2e25d7b64b3..2c856fc47ae3 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -94,6 +94,12 @@ extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);
extern int __legitimize_mnt(struct vfsmount *, unsigned);
extern bool legitimize_mnt(struct vfsmount *, unsigned);
+static inline bool __path_is_mountpoint(const struct path *path)
+{
+ struct mount *m = __lookup_mnt(path->mnt, path->dentry);
+ return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
+}
+
extern void __detach_mounts(struct dentry *dentry);
static inline void detach_mounts(struct dentry *dentry)