Date: Mon, 12 Jan 2009 02:31:38 +0000
From: Jamie Lokier <jamie@shareable.org>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Grissiom <chaos.proton@gmail.com>, linux-kernel@vger.kernel.org,
       linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH] async: Don't call async_synchronize_full_special()	while holding sb_lock
Message-ID: <20090112023138.GD6428@shareable.org>
References: <a0adeea50901080007q5a3ed5c8y5a744ce37e677325@mail.gmail.com> <1231425472.21528.13.camel@norville.austin.ibm.com> <20090108072111.1ebadebd@infradead.org> <1231429591.27353.14.camel@norville.austin.ibm.com> <20090108225050.GL9448@disturbed> <49668388.708@linux.intel.com> <20090109014054.GN9448@disturbed> <4966D652.4070105@linux.intel.com>
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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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