[PATCH 3/6 v9] path: New helpers path_get_pin/path_put_unpin for path pin

From: Kinglong Mee <kinglongmee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: "J. Bruce Fields"
	<bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>,
	Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Cc: "linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	NeilBrown <neilb-l3A5Bk7waGM@public.gmane.org>,
	Trond Myklebust
	<trond.myklebust-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>,
	kinglongmee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Subject: [PATCH 3/6 v9] path: New helpers path_get_pin/path_put_unpin for path pin
Date: Tue, 18 Aug 2015 15:20:31 +0800	[thread overview]
Message-ID: <55D2DCBF.3070106@gmail.com> (raw)
In-Reply-To: <55D2DBF6.3010406-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

Two helpers for filesystem pining to vfsmnt, not mntget.

v9, Update base on NeilBrown's new patch

Signed-off-by: Kinglong Mee <kinglongmee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 fs/namei.c           | 26 ++++++++++++++++++++++++++
 include/linux/path.h |  4 ++++
 2 files changed, 30 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index 1c2105e..4f95e16 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -492,6 +492,32 @@ void path_put(const struct path *path)
 }
 EXPORT_SYMBOL(path_put);
 
+/**
+ * path_get_pin - get a reference to a path's dentry
+ *                and pin to path's vfsmnt
+ * @path: path to get the reference to
+ * @p: the fs_pin pin to vfsmnt
+ */
+void path_get_pin(struct path *path, struct fs_pin *p)
+{
+	dget(path->dentry);
+	pin_insert_group(p, path->mnt, NULL);
+}
+EXPORT_SYMBOL(path_get_pin);
+
+/**
+ * path_put_unpin - put a reference to a path's dentry
+ *                  and remove pin to path's vfsmnt
+ * @path: path to put the reference to
+ * @p: the fs_pin removed from vfsmnt
+ */
+int path_put_unpin(struct path *path, struct fs_pin *p)
+{
+	dput(path->dentry);
+	return pin_remove(p);
+}
+EXPORT_SYMBOL(path_put_unpin);
+
 #define EMBEDDED_LEVELS 2
 struct nameidata {
 	struct path	path;
diff --git a/include/linux/path.h b/include/linux/path.h
index d137218..40d376a 100644
--- a/include/linux/path.h
+++ b/include/linux/path.h
@@ -3,6 +3,7 @@
 
 struct dentry;
 struct vfsmount;
+struct fs_pin;
 
 struct path {
 	struct vfsmount *mnt;
@@ -12,6 +13,9 @@ struct path {
 extern void path_get(const struct path *);
 extern void path_put(const struct path *);
 
+extern void path_get_pin(struct path *, struct fs_pin *);
+extern int path_put_unpin(struct path *, struct fs_pin *);
+
 static inline int path_equal(const struct path *path1, const struct path *path2)
 {
 	return path1->mnt == path2->mnt && path1->dentry == path2->dentry;
-- 
2.4.3

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