From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Sterba <dsterba@suse.cz>
Date: Thu, 3 Sep 2020 11:11:23 +0200
Subject: [LTP] [btrfs] c0aaf9b7a1: ltp: stuck at diotest4
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Message-ID: <20200903091123.GO28318@suse.cz>
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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.