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Date:   Tue, 25 Aug 2020 13:16:16 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Jan Kara <jack@suse.cz>
Cc:     linux-fsdevel@vger.kernel.org, yebin <yebin10@huawei.com>,
        Christoph Hellwig <hch@infradead.org>,
        linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH RFC 2/2] block: Do not discard buffers under a mounted
 filesystem
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On Tue, Aug 25, 2020 at 02:05:54PM +0200, Jan Kara wrote:
> Discarding blocks and buffers under a mounted filesystem is hardly
> anything admin wants to do. Usually it will confuse the filesystem and
> sometimes the loss of buffer_head state (including b_private field) can
> even cause crashes like:

Doesn't work if the file system uses multiple devices.  I think we
just really need to split the fs buffer_head address space from the
block device one.  Everything else is just going to cause a huge mess.