linux-ext4 - Re: [PATCH v3 2/2] jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer

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Date:   Tue, 18 Feb 2020 12:04:42 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     "zhangyi (F)" <yi.zhang@...wei.com>
Cc:     Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
        luoshijie1@...wei.com, zhangxiaoxu5@...wei.com
Subject: Re: [PATCH v3 2/2] jbd2: do not clear the BH_Mapped flag when
 forgetting a metadata buffer

On Mon, Feb 17, 2020 at 06:38:23PM +0800, zhangyi (F) wrote:
> >> +			/*
> >> +			 * Block device buffers need to stay mapped all the
> >> +			 * time, so it is enough to clear buffer_jbddirty and
> >> +			 * buffer_freed bits. For the file mapping buffers (i.e.
> >> +			 * journalled data) we need to unmap buffer and clear
> >> +			 * more bits. We also need to be careful about the check
> >> +			 * because the data page mapping can get cleared under
> >> +			 * out hands, which alse need not to clear more bits
> > 			   ^^^ our    ^^^^ Maybe I'd rephrase this like:
> > 
> > ... under our hands. Note that if mapping == NULL, we don't need to make
> > buffer unmapped because the page is already detached from the mapping and
> > buffers cannot get reused.
> > 
> Thanks for your suggestion, Ted has already pushed this patch to upstream,
> I could write an appending patch to fix this.

Feel free to send a patch to fix up the comment if you like.

Thanks,

					- Ted