ANDROID: fs/fuse: Keep FUSE file times consistent with lower file

When FUSE passthrough is used, the lower file system file is manipulated
directly, but neither mtime, atime or ctime of the referencing FUSE file
is updated.

Fix by updating the file times when passthrough operations are
performed.

Bug: 200779468
Bug: 201730208
Reported-by: Fengnan Chang <changfengnan@vivo.com>
Reported-by: Ed Tsai <ed.tsai@mediatek.com>
Signed-off-by: Alessio Balsini <balsini@google.com>
Change-Id: I35b72196b2cc1d79a9f62ddb32e2cfa934c3b6d3

fs/fuse/passthrough.c

@@ -26,11 +26,34 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
 	};
 }
 
+static void fuse_file_accessed(struct file *dst_file, struct file *src_file)
+{
+	struct inode *dst_inode;
+	struct inode *src_inode;
+
+	if (dst_file->f_flags & O_NOATIME)
+		return;
+
+	dst_inode = file_inode(dst_file);
+	src_inode = file_inode(src_file);
+
+	if ((!timespec64_equal(&dst_inode->i_mtime, &src_inode->i_mtime) ||
+	     !timespec64_equal(&dst_inode->i_ctime, &src_inode->i_ctime))) {
+		dst_inode->i_mtime = src_inode->i_mtime;
+		dst_inode->i_ctime = src_inode->i_ctime;
+	}
+
+	touch_atime(&dst_file->f_path);
+}
+
 static void fuse_copyattr(struct file *dst_file, struct file *src_file)
 {
 	struct inode *dst = file_inode(dst_file);
 	struct inode *src = file_inode(src_file);
 
+	dst->i_atime = src->i_atime;
+	dst->i_mtime = src->i_mtime;
+	dst->i_ctime = src->i_ctime;
 	i_size_write(dst, i_size_read(src));
 }
 
@@ -96,6 +119,8 @@ ssize_t fuse_passthrough_read_iter(struct kiocb *iocb_fuse,
 out:
 	revert_creds(old_cred);
 
+	fuse_file_accessed(fuse_filp, passthrough_filp);
+
 	return ret;
 }
 
@@ -115,6 +140,8 @@ ssize_t fuse_passthrough_write_iter(struct kiocb *iocb_fuse,
 
 	inode_lock(fuse_inode);
 
+	fuse_copyattr(fuse_filp, passthrough_filp);
+
 	old_cred = override_creds(ff->passthrough.cred);
 	if (is_sync_kiocb(iocb_fuse)) {
 		file_start_write(passthrough_filp);
@@ -155,9 +182,7 @@ ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma)
 	int ret;
 	const struct cred *old_cred;
 	struct fuse_file *ff = file->private_data;
-	struct inode *fuse_inode = file_inode(file);
 	struct file *passthrough_filp = ff->passthrough.filp;
-	struct inode *passthrough_inode = file_inode(passthrough_filp);
 
 	if (!passthrough_filp->f_op->mmap)
 		return -ENODEV;
@@ -176,17 +201,7 @@ ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma)
 	else
 		fput(file);
 
-	if (file->f_flags & O_NOATIME)
-		return ret;
-
-	if ((!timespec64_equal(&fuse_inode->i_mtime,
-			       &passthrough_inode->i_mtime) ||
-	     !timespec64_equal(&fuse_inode->i_ctime,
-			       &passthrough_inode->i_ctime))) {
-		fuse_inode->i_mtime = passthrough_inode->i_mtime;
-		fuse_inode->i_ctime = passthrough_inode->i_ctime;
-	}
-	touch_atime(&file->f_path);
+	fuse_file_accessed(file, passthrough_filp);
 
 	return ret;
 }