Re: [btrfs] c0aaf9b7a1: ltp: stuck at diotest4

[David Sterba]

On Thu, Sep 03, 2020 at 02:28:37PM +0800, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed the following commit (built with gcc-9):
> 
> commit: c0aaf9b7a114f6b75e0da97be7d99c102347a751 ("btrfs: switch to iomap_dio_rw() for dio")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master

That's probably the O_DIRECT + O_(D)SYNC deadlock that was found
recently. One of the cases in diotest4 does

	open(filename, O_DIRECT | O_RDWR | O_SYNC)

Fix is work in progress, thanks for the report.