linux-ext4 - Re: [PATCH] ext4: ext4_read_bh_lock() should submit IO if the buffer isn't uptodate

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Message-Id: <166450797715.256913.16436347919601739345.b4-ty@mit.edu>
Date:   Thu, 29 Sep 2022 23:19:46 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     linux-ext4@...r.kernel.org, Zhang Yi <yi.zhang@...wei.com>
Cc:     "Theodore Ts'o" <tytso@....edu>, adilger.kernel@...ger.ca,
        openglfreak@...glemail.com, jack@...e.cz, yukuai3@...wei.com
Subject: Re: [PATCH] ext4: ext4_read_bh_lock() should submit IO if the buffer isn't uptodate

On Wed, 31 Aug 2022 15:46:29 +0800, Zhang Yi wrote:
> Recently we notice that ext4 filesystem occasionally fail to read
> metadata from disk and report error message, but the disk and block
> layer looks fine. After analyse, we lockon commit 88dbcbb3a484
> ("blkdev: avoid migration stalls for blkdev pages"). It provide a
> migration method for the bdev, we could move page that has buffers
> without extra users now, but it lock the buffers on the page, which
> breaks the fragile metadata read operation on ext4 filesystem,
> ext4_read_bh_lock() was copied from ll_rw_block(), it depends on the
> assumption of that locked buffer means it is under IO. So it just
> trylock the buffer and skip submit IO if it lock failed, after
> wait_on_buffer() we conclude IO error because the buffer is not
> uptodate.
> 
> [...]

Applied, thanks!

[1/1] ext4: ext4_read_bh_lock() should submit IO if the buffer isn't uptodate
      commit: 07e3f4273ff54a4c891f05e9f0f0c842b46578a7

Best regards,
-- 
Theodore Ts'o <tytso@....edu>