linux-ext4 - Re: [PATCH] ext4: remove trivial nowait check for buffered write

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Date:   Sat, 1 Feb 2020 17:49:51 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     qiwuchen55@...il.com
Cc:     adilger.kernel@...ger.ca, trivial@...nel.org,
        linux-ext4@...r.kernel.org, chenqiwu <chenqiwu@...omi.com>
Subject: Re: [PATCH] ext4: remove trivial nowait check for buffered write

On Sat, Feb 01, 2020 at 12:00:39PM +0800, qiwuchen55@...il.com wrote:
> From: chenqiwu <chenqiwu@...omi.com>
> 
> Remove trivial nowait check for ext4_buffered_write_iter(),
> since buffered writes will return -EINVAL if IOCB_NOWAIT
> passed in the follow-up function ext4_write_checks()->
> ext4_generic_write_checks()->generic_write_checks().
> 
> Signed-off-by: chenqiwu <chenqiwu@...omi.com>

The reason why we do this check here is so that we return immediately
and not potentially block when we call inode_lock().  Otherwise, an
AIO request with IOCB_NOWAIT could block, and that's not allowed.

    	    	 	     	   	  - Ted