From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [PATCH 1/3] f2fs: avoid calling i_size_read when it's unnecessary Date: Wed, 30 Dec 2015 10:27:39 -0800 Message-ID: <20151230182739.GC28564@jaegeuk.local> References: <000c01d142df$24fdd450$6ef97cf0$@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1aELTK-00016k-HS for linux-f2fs-devel@lists.sourceforge.net; Wed, 30 Dec 2015 18:27:42 +0000 Received: from mail.kernel.org ([198.145.29.136]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1aELTJ-0005FO-Jv for linux-f2fs-devel@lists.sourceforge.net; Wed, 30 Dec 2015 18:27:42 +0000 Content-Disposition: inline In-Reply-To: <000c01d142df$24fdd450$6ef97cf0$@samsung.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Fan Li Cc: linux-f2fs-devel@lists.sourceforge.net Hi Fan, On Wed, Dec 30, 2015 at 04:49:56PM +0800, Fan Li wrote: > i_size_read does more than reading a value, it's best that we use it > only when we need it. > > Signed-off-by: Fan li > --- > fs/f2fs/data.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index d67c599..a9a4d89 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -780,7 +780,7 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > { > struct buffer_head map_bh; > sector_t start_blk, last_blk; > - loff_t isize = i_size_read(inode); > + loff_t isize; > u64 logical = 0, phys = 0, size = 0; > u32 flags = 0; > int ret = 0; > @@ -795,6 +795,8 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > return ret; > } > > + isize = i_size_read(inode); It seems that we need to get isize after grabbing i_mutex below in order to avoid data race. Thanks, > + > mutex_lock(&inode->i_mutex); > if (start >= isize) > goto out; > -- > 1.7.9.5 > ------------------------------------------------------------------------------