linux-kernel - Re: [PATCH] async: Don't call async_synchronize_full_special() while holding sb

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Date:	Mon, 12 Jan 2009 02:31:38 +0000
From:	Jamie Lokier <jamie@...reable.org>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Grissiom <chaos.proton@...il.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] async: Don't call async_synchronize_full_special()	while holding sb_lock

Arjan van de Ven wrote:
> >	- removing a million files and queuing all of the
> >	  deletes in the async queues....
> 
> the async code throttles at 32k outstanding.
> Yes 32K is arbitrary, but if you delete  a million files fast, all but the 
> first few thousand are
> synchronous.

Hmm.

If I call unlink() a thousand times and then call fsync() on the
parent directories covering files I've unlinked... I expect the
deletes to be committed to disk when the last fsync() has returned.  I
require that a crash and restart will not see the files.  Several
kinds of transactional software and even some shell scripts expect this.

Will these asynchronous deletes break the guaranteed
commit-of-the-delete provided by fsync() on the parent directory?

-- Jamie
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