linux-kernel - Re: [PATCH v2 1/5] ext4: Fix reusing stale buffer heads from last failed mounting

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Date:   Tue, 14 Mar 2023 13:11:25 +0100
From:   Jan Kara <jack@...e.cz>
To:     Zhihao Cheng <chengzhihao1@...wei.com>
Cc:     Jan Kara <jack@...e.cz>, tytso@....edu, adilger.kernel@...ger.ca,
        jack@...e.com, tudor.ambarus@...aro.org,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com
Subject: Re: [PATCH v2 1/5] ext4: Fix reusing stale buffer heads from last
 failed mounting

On Tue 14-03-23 20:01:46, Zhihao Cheng wrote:
> 在 2023/3/14 19:33, Jan Kara 写道:
> Hi Jan,
> 
> > 
> > > @@ -1271,14 +1277,8 @@ static void ext4_put_super(struct super_block *sb)
> > >   	sync_blockdev(sb->s_bdev);
> > >   	invalidate_bdev(sb->s_bdev);
> 
> For journal in the inode case, journal bhs come from block device, which
> means buffers will be dropped after this line 'invalidate_bdev(sb->s_bdev)'
> being executed.

Right, I've missed that. But then why do you remove the sbi->s_journal_bdev
!= sb->s_bdev condition below?

> > > -	if (sbi->s_journal_bdev && sbi->s_journal_bdev != sb->s_bdev) {
> > > -		/*
> > > -		 * Invalidate the journal device's buffers.  We don't want them
> > > -		 * floating about in memory - the physical journal device may
> > > -		 * hotswapped, and it breaks the `ro-after' testing code.
> > > -		 */
> > > +	if (sbi->s_journal_bdev) {
> > >   		sync_blockdev(sbi->s_journal_bdev);
> > > -		invalidate_bdev(sbi->s_journal_bdev);
> > >   		ext4_blkdev_remove(sbi);
> > >   	}
> >  > Hum, but this will invalidate bhs only if journal is stored on a block
> > device. If journal is in the inode (the common case), we won't invalidate
> > anything (sbi->s_journal_bdev is NULL) and the same problem can happen?
> > 

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR