linux-kernel - Re: [PATCH] fs/buffer: adjust the order of might_sleep() in __getblk

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Date:   Thu, 23 Mar 2023 12:23:33 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     gouhao@...ontech.com
Cc:     viro@...iv.linux.org.uk, brauner@...nel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs/buffer: adjust the order of might_sleep() in
 __getblk_gfp()

On Thu, Mar 23, 2023 at 05:37:52PM +0800, gouhao@...ontech.com wrote:
> From: Gou Hao <gouhao@...ontech.com>
> 
> If 'bh' is found in cache, just return directly.
> might_sleep() is only required on slow paths.

You're missing the point.  The caller can't know whether the slow or
fast path will be taken.  So it must _never_ call this function if it
cannot sleep.