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From: Alex Zhuravlev <azhuravlev@whamcloud.com>
To: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 1/2] ext4:  mballoc - prefetching for bitmaps
Date: Sat, 30 May 2020 04:57:39 +0000	[thread overview]
Message-ID: <1877745A-989A-4402-A0F5-BB5B4CA37AA5@whamcloud.com> (raw)
In-Reply-To: <20200528144746.GE228632@mit.edu>



> On 28 May 2020, at 17:47, Theodore Y. Ts'o <tytso@mit.edu> wrote:
> 
> What are you trying to do here?  If nr > 0, we return; if nr < 0, we
> BUG() --- but nr is an unsigned int, so we never can trigger --- which
> was the warning reported by the kbuild test bot.  So we will only get
> past this point if ac_prefetch == group.  But ac_prefetch appears to
> be the last group that we prefetched, so it's not clear that the logic
> is correct here.

You’re right, this part “evolved” since the initial version, but I forgot to make it clear.
Basically this should be replaced with:

If (ac->ac_prefetch != group)
	return;

ac->ac_prefetch is just a cursor for the current process.

Thanks, Alex


  reply	other threads:[~2020-05-30  4:57 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-15 10:07 [PATCH 1/2] ext4: mballoc - prefetching for bitmaps Alex Zhuravlev
2020-05-20  4:45 ` kbuild test robot
2020-05-23 19:27 ` kbuild test robot
2020-05-28 14:47 ` Theodore Y. Ts'o
2020-05-30  4:57   ` Alex Zhuravlev [this message]
2020-05-29 16:19 ` Благодаренко Артём
2020-05-30  5:01   ` Alex Zhuravlev
2020-06-19 17:16     ` Theodore Y. Ts'o
2020-06-19 18:23       ` Alex Zhuravlev

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