From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [RFC][PATCH 3/9 v1] ext4: add physical block and status member into extent status tree Date: Mon, 31 Dec 2012 22:49:52 +0100 Message-ID: <20121231214952.GL7564@quack.suse.cz> References: <1356335742-11793-1-git-send-email-wenqing.lz@taobao.com> <1356335742-11793-4-git-send-email-wenqing.lz@taobao.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, Zheng Liu To: Zheng Liu Return-path: Received: from cantor2.suse.de ([195.135.220.15]:38124 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750957Ab2LaVtz (ORCPT ); Mon, 31 Dec 2012 16:49:55 -0500 Content-Disposition: inline In-Reply-To: <1356335742-11793-4-git-send-email-wenqing.lz@taobao.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 24-12-12 15:55:36, Zheng Liu wrote: > From: Zheng Liu > > es_pblk is used to record physical block that maps to the disk. es_status is > used to record the status of the extent. Three status are defined, which are > written, unwritten and delayed. So this means one extent is 48 bytes on 64-bit architectures. If I'm a nasty user and create artificially fragmented file (by allocating every second block), extent tree takes 6 MB per GB of file. That's quite a bit and I think you need to provide a way for kernel to reclaim extent structures... Honza > > Signed-off-by: Zheng Liu > --- > fs/ext4/extents_status.h | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h > index 81e9339..85115bb 100644 > --- a/fs/ext4/extents_status.h > +++ b/fs/ext4/extents_status.h > @@ -20,10 +20,18 @@ > #define es_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__) > #endif > > +enum { > + EXTENT_STATUS_WRITTEN = 0, /* written extent */ > + EXTENT_STATUS_UNWRITTEN = 1, /* unwritten extent */ > + EXTENT_STATUS_DELAYED = 2, /* delayed extent */ > +}; > + > struct extent_status { > struct rb_node rb_node; > ext4_lblk_t es_lblk; /* first logical block extent covers */ > ext4_lblk_t es_len; /* length of extent in block */ > + ext4_fsblk_t es_pblk; /* first physical block */ > + int es_status; /* record the status of extent */ > }; > > struct ext4_es_tree { > -- > 1.7.12.rc2.18.g61b472e > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jan Kara SUSE Labs, CR