From: Andreas Dilger Subject: Re: Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?) Date: Fri, 15 Apr 2011 23:11:23 -0600 Message-ID: References: <20110414102608.GA1678@x4.trippels.de> <20110414120635.GB1678@x4.trippels.de> <20110414140222.GB1679@x4.trippels.de> <4DA70BD3.1070409@draigBrady.com> <4DA717B2.3020305@sandeen.net> <20110414225904.GK21395@dastard> <4DA7836A.5040604@draigBrady.com> <20110415000940.GL21395@dastard> <76FFF648-CA02-494B-A862-566C66A8CB82@dilger.ca> <20110416005040.GP21395@dastard> Mime-Version: 1.0 (iPhone Mail 8G4) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Cc: Eric Sandeen , xfs-oss , "coreutils-mXXj517/zsQ@public.gmane.org" , "linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Markus Trippelsdorf To: Dave Chinner Return-path: In-Reply-To: <20110416005040.GP21395@dastard> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: coreutils-bounces+gcgcg-coreutils=m.gmane.org-mXXj517/zsQ@public.gmane.org Sender: coreutils-bounces+gcgcg-coreutils=m.gmane.org-mXXj517/zsQ@public.gmane.org List-Id: linux-ext4.vger.kernel.org On 2011-04-15, at 6:50 PM, Dave Chinner wrote: > What you are suggesting is that FIEMAP needs to be page cache > coherent, and that is far, far away from the intended use of the > interface. Even consiering that you need to looking for active pages > in the page cache when mapping extents say to me that you are > doing something very wrong. >=20 > Unwritten extents remain unwritten until the data is physically > written to them. Therefore, to change their state, you need to sync > the data covering the range. In that case, it means cp should just always use FIEMAP_FLAG_SYNC, which is f= ine.=20 Cheers, Andreas