From: Josef Bacik Subject: Re: [PATCH 4/6] Ext4: fail if we try to use hole punch Date: Tue, 16 Nov 2010 11:33:21 -0500 Message-ID: <20101116163320.GB2524@localhost.localdomain> References: <1289840723-3056-1-git-send-email-josef@redhat.com> <1289840723-3056-5-git-send-email-josef@redhat.com> <4CE2AF5B.7020500@draigBrady.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Josef Bacik , david@fromorbit.com, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, cmm@us.ibm.com, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com To: =?iso-8859-1?Q?P=E1draig?= Brady Return-path: Content-Disposition: inline In-Reply-To: <4CE2AF5B.7020500@draigBrady.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, Nov 16, 2010 at 04:20:43PM +0000, P=E1draig Brady wrote: > On 15/11/10 17:05, Josef Bacik wrote: > > Ext4 doesn't have the ability to punch holes yet, so make sure we r= eturn > > EOPNOTSUPP if we try to use hole punching through fallocate. This = support can > > be added later. Thanks, > >=20 > > Signed-off-by: Josef Bacik > > --- > > fs/ext4/extents.c | 4 ++++ > > 1 files changed, 4 insertions(+), 0 deletions(-) > >=20 > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > > index 0554c48..35bca73 100644 > > --- a/fs/ext4/extents.c > > +++ b/fs/ext4/extents.c > > @@ -3622,6 +3622,10 @@ long ext4_fallocate(struct inode *inode, int= mode, loff_t offset, loff_t len) > > struct ext4_map_blocks map; > > unsigned int credits, blkbits =3D inode->i_blkbits; > > =20 > > + /* We only support the FALLOC_FL_KEEP_SIZE mode */ > > + if (mode && (mode !=3D FALLOC_FL_KEEP_SIZE)) > > + return -EOPNOTSUPP; > > + > > /* > > * currently supporting (pre)allocate mode for extent-based > > * files _only_ >=20 > So for older versions of ext4 or other filesystems, how do we know > that fallocate(...,FALLOC_FL_PUNCH_HOLE) is not supported. > I.E. how do we detect at runtime that the call succeeded > and didn't just do a normal fallocate()? > Older kernels won't accept FALLOC_FL_PUNCH_HOLE, so you'll get an error= =2E Thanks, Josef=20