[PATCH 4.4 61/63] usb: gadget: f_fs: Fix use-after-free in ffs_fs_kill_sb()

4.4-stable review patch. If anyone has any objections, please let me know. -- From: Xinyong commit 1a087f032111a88e826877449dfb93ceb22b78b9 upstream. When I debug a kernel crash issue in funcitonfs, found ffs_data.ref overflowed, While

[PATCH 4.4 61/63] usb: gadget: f_fs: Fix use-after-free in ffs_fs_kill_sb()

4.4-stable review patch. If anyone has any objections, please let me know. -- From: Xinyong commit 1a087f032111a88e826877449dfb93ceb22b78b9 upstream. When I debug a kernel crash issue in funcitonfs, found ffs_data.ref overflowed, While functionfs is unmounting, ffs_data is