From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Aneesh Kumar K. V" Subject: Re: [PATCH -V7 6/9] ext4: Add get_fsid callback Date: Fri, 14 May 2010 23:51:56 +0530 Message-ID: <87aas2e43f.fsf@linux.vnet.ibm.com> References: <1273679444-14903-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1273679444-14903-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <4BED8933.4060100@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: hch@infradead.org, viro@zeniv.linux.org.uk, adilger@sun.com, corbet@lwn.net, serue@us.ibm.com, neilb@suse.de, linux-fsdevel@vger.kernel.org, sfrench@us.ibm.com, philippe.deniel@CEA.FR, linux-kernel@vger.kernel.org To: coly.li@suse.de Return-path: Received: from e28smtp02.in.ibm.com ([122.248.162.2]:45373 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751191Ab0ENSWN (ORCPT ); Fri, 14 May 2010 14:22:13 -0400 In-Reply-To: <4BED8933.4060100@suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sat, 15 May 2010 01:32:35 +0800, Coly Li wrote: > > > On 05/12/2010 11:50 PM, Aneesh Kumar K.V Wrote: > > Acked-by: Serge Hallyn > > Signed-off-by: Aneesh Kumar K.V > > --- > > fs/ext4/super.c | 15 +++++++++++++++ > > 1 files changed, 15 insertions(+), 0 deletions(-) > > > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > > index e14d22c..fc7d464 100644 > > --- a/fs/ext4/super.c > > +++ b/fs/ext4/super.c > > @@ -1049,6 +1049,19 @@ static int bdev_try_to_free_page(struct super_block *sb, struct page *page, > > return try_to_free_buffers(page); > > } > > > > +static int ext4_get_fsid(struct super_block *sb, struct uuid *fsid) > > +{ > > + struct ext4_sb_info *sbi = EXT4_SB(sb); > > + struct ext4_super_block *es = sbi->s_es; > > + > > + memcpy(fsid->uuid, es->s_uuid, sizeof(fsid->uuid)); > > + /* > > + * We may want to make sure we return error if the s_uuid is not > > + * exactly unique > > + */ > > + return 0; > > +} > > + > > #ifdef CONFIG_QUOTA > > #define QTYPE2NAME(t) ((t) == USRQUOTA ? "user" : "group") > > #define QTYPE2MOPT(on, t) ((t) == USRQUOTA?((on)##USRJQUOTA):((on)##GRPJQUOTA)) > > @@ -1109,6 +1122,7 @@ static const struct super_operations ext4_sops = { > > .quota_write = ext4_quota_write, > > #endif > > .bdev_try_to_free_page = bdev_try_to_free_page, > > + .get_fsid = ext4_get_fsid, > > }; > > > > static const struct super_operations ext4_nojournal_sops = { > > @@ -1128,6 +1142,7 @@ static const struct super_operations ext4_nojournal_sops = { > > .quota_write = ext4_quota_write, > > #endif > > .bdev_try_to_free_page = bdev_try_to_free_page, > > + .get_fsid = ext4_get_fsid, > > }; > > > > Hi Aneesh, > > Just wondering why not call sb->s_op->statfs() to get the fsid in do_sys_name_to_handle() ? > The overhead is a little bit more code to get fsid from struct kstatfs, but we can gain, > 1) avoid to have one more callback in struct super_operations. > 2) more file system can be supported (since most of file systems have statfs() call back) > sb->s_op->statfs returns fsid of type __kernel_fsid_t which is just 64bits. -aneesh