[PATCH v4 10/15] vfs: add vfs_get_fsid() helper

[Amir Goldstein <amir73il@gmail.com>]

Wrapper around statfs() interface.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/statfs.c            | 14 ++++++++++++++
 include/linux/statfs.h |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/fs/statfs.c b/fs/statfs.c
index f0216629621d..eea7af6f2f22 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -67,6 +67,20 @@ static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
 	return retval;
 }
 
+int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
+{
+	struct kstatfs st;
+	int error;
+
+	error = statfs_by_dentry(dentry, &st);
+	if (error)
+		return error;
+
+	*fsid = st.f_fsid;
+	return 0;
+}
+EXPORT_SYMBOL(vfs_get_fsid);
+
 int vfs_statfs(const struct path *path, struct kstatfs *buf)
 {
 	int error;
diff --git a/include/linux/statfs.h b/include/linux/statfs.h
index 3142e98546ac..9bc69edb8f18 100644
--- a/include/linux/statfs.h
+++ b/include/linux/statfs.h
@@ -41,4 +41,7 @@ struct kstatfs {
 #define ST_NODIRATIME	0x0800	/* do not update directory access times */
 #define ST_RELATIME	0x1000	/* update atime relative to mtime/ctime */
 
+struct dentry;
+extern int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid);
+
 #endif
-- 
2.17.1