From: Mingming Cao Subject: Re: [PATCH 3/6] ext2 balloc: fix off-by-one against rsv_end Date: Tue, 28 Nov 2006 11:42:16 -0800 Message-ID: <1164742936.3769.42.camel@dyn9047017103.beaverton.ibm.com> References: <20061114014125.dd315fff.akpm@osdl.org> <20061114184919.GA16020@skynet.ie> <20061114113120.d4c22b02.akpm@osdl.org> <20061115214534.72e6f2e8.akpm@osdl.org> <455C0B6F.7000201@us.ibm.com> <20061115232228.afaf42f2.akpm@osdl.org> <1163666960.4310.40.camel@localhost.localdomain> <20061116011351.1401a00f.akpm@osdl.org> <1163708116.3737.12.camel@dyn9047017103.beaverton.ibm.com> <20061116132724.1882b122.akpm@osdl.org> <1164073652.20900.34.camel@dyn9047017103.beaverton.ibm.com> <1164156193.3804.48.camel@dyn9047017103.beaverton.ibm.com> Reply-To: cmm@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Andrew Morton , Mel Gorman , "Martin J. Bligh" , linux-kernel@vger.kernel.org, "linux-ext4@vger.kernel.org" Return-path: Received: from e33.co.us.ibm.com ([32.97.110.151]:61149 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S936070AbWK1TmU (ORCPT ); Tue, 28 Nov 2006 14:42:20 -0500 To: Hugh Dickins In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, 2006-11-28 at 17:41 +0000, Hugh Dickins wrote: > rsv_end is the last block within the reservation, > so alloc_new_reservation should accept start_block == rsv_end as success. > > Signed-off-by: Hugh Dickins > --- > Thanks, Acked. This is not a problem for now, as the default window size is 8 blocks, and we never shrink the window size. But it could be a issue in the future, if the reservation window could be dynamically shrink, when it keep failing to create a new(large) reservation window, or we keep throw away a just-allocated-window as the application is doing very seeky random write. > fs/ext2/balloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 2.6.19-rc6-mm2/fs/ext2/balloc.c 2006-11-24 08:18:02.000000000 +0000 > +++ linux/fs/ext2/balloc.c 2006-11-27 19:28:41.000000000 +0000 > @@ -950,7 +950,7 @@ retry: > * check if the first free block is within the > * free space we just reserved > */ > - if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end) > + if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end) > return 0; /* success */ > /* > * if the first free bit we found is out of the reservable space