[PATCH 04/14] btrfs: use vfs_utimes to update file timestamps

[Christoph Hellwig]

Btrfs updates the device node timestamps for block device special files
when it stop using the device.

Commit 8f96a5bfa150 ("btrfs: update the bdev time directly when closing")
switch that update from the correct layering to directly call the
low-level helper on the bdev inode.  This is wrong and got fixed in
commit 54fde91f52f5 ("btrfs: update device path inode time instead of
bd_inode") by updating the file system inode instead of the bdev inode,
but this kept the incorrect bypassing of the VFS interfaces and file
system ->update_times method.  Fix this by using the propet vfs_utimes
interface.

Fixes: 8f96a5bfa150 ("btrfs: update the bdev time directly when closing")
Fixes: 54fde91f52f5 ("btrfs: update device path inode time instead of bd_inode")
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 fs/btrfs/volumes.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2bec544d8ba3..259e8b0496df 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2002,14 +2002,11 @@ static int btrfs_add_dev_item(struct btrfs_trans_handle *trans,
 static void update_dev_time(const char *device_path)
 {
 	struct path path;
-	int ret;
 
-	ret = kern_path(device_path, LOOKUP_FOLLOW, &path);
-	if (ret)
-		return;
-
-	inode_update_time(d_inode(path.dentry), S_MTIME | S_CTIME | S_VERSION);
-	path_put(&path);
+	if (!kern_path(device_path, LOOKUP_FOLLOW, &path)) {
+		vfs_utimes(&path, NULL);
+		path_put(&path);
+	}
 }
 
 static int btrfs_rm_dev_item(struct btrfs_trans_handle *trans,
-- 
2.47.3