[PATCH 4/9] pidfs: add pidfs_root_path() helper

[Christian Brauner <brauner@kernel.org>]

Allow to return the root of the global pidfs filesystem.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/internal.h |  1 +
 fs/pidfs.c    | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/fs/internal.h b/fs/internal.h
index 22ba066d1dba..ad256bccdc85 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -353,3 +353,4 @@ int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path,
 		       unsigned int query_flags);
 int anon_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		       struct iattr *attr);
+void pidfs_get_root(struct path *path);
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 1cf66fd9961e..1b7bd14366dc 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -31,6 +31,14 @@
 static struct kmem_cache *pidfs_attr_cachep __ro_after_init;
 static struct kmem_cache *pidfs_xattr_cachep __ro_after_init;
 
+static struct path pidfs_root_path = {};
+
+void pidfs_get_root(struct path *path)
+{
+	*path = pidfs_root_path;
+	path_get(path);
+}
+
 /*
  * Stashes information that userspace needs to access even after the
  * process has been reaped.
@@ -1065,4 +1073,7 @@ void __init pidfs_init(void)
 	pidfs_mnt = kern_mount(&pidfs_type);
 	if (IS_ERR(pidfs_mnt))
 		panic("Failed to mount pidfs pseudo filesystem");
+
+	pidfs_root_path.mnt = pidfs_mnt;
+	pidfs_root_path.dentry = pidfs_mnt->mnt_root;
 }

-- 
2.47.2