linux-kernel - Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch

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Date:	Tue, 09 Apr 2013 17:56:15 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	Jason Hrycay <jhrycay@...il.com>, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net, C.Fries@...orola.com,
	jason.hrycay@...orola.com
Subject: Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

2013-04-09 (화), 15:46 +0900, Namjae Jeon:
> 2013/4/9, Jason Hrycay <jhrycay@...il.com>:
> > From: Jason Hrycay <jason.hrycay@...orola.com>
> >
> > Move the f2fs_balance_fs out of the truncate_hole function and only
> > perform that in punch_hole use case.  The commit:
> >
> >   ed60b1644e7f7e5dd67d21caf7e4425dff05dad0
> >
> > intended to do this but moved it into truncate_hole to cover more
> > cases.  However, a deadlock scenario is possible when deleting an inode
> > entry under specific conditions:
> >
> >  f2fs_delete_entry()
> >      mutex_lock_op(sbi, DENTRY_OPS);
> >      truncate_hole()
> >          f2fs_balance_fs()
> >              mutex_lock(&sbi->gc_mutex);
> >              f2fs_gc()
> >                  write_checkpoint()
> >                      block_operations()
> >                          mutex_lock_op(sbi, DENTRY_OPS);
> >
> > Lets move it into the punch_hole case to cover the original intent of
> > avoiding it during fallocate's expand_inode_data case.
> >
> > Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
> > Signed-off-by: Jason Hrycay <jason.hrycay@...orola.com>
> Hi,
> With the latest commit 9995bf953a83749abd9fa22f72ab2b0be341025a
> About introducing the global locking method in ‘f2fs’,
> I think we no longer will have a case of deadlock happening in this path.

Hi, Namjae.
I found that this bug still exists in the new locking model.
Please see the v3 patch. :)
Thanks,

> 
> Thanks.

-- 
Jaegeuk Kim
Samsung

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