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

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Date:	Tue, 9 Apr 2013 15:46:02 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	Jason Hrycay <jhrycay@...il.com>
Cc:	jaegeuk.kim@...sung.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

2013/4/9, 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.

Thanks.
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