From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Subject: Re: [PATCH 3/6] direct-io: do not merge logically non-contiguous requests Date: Sat, 22 May 2010 10:02:17 -0400 Message-ID: <20100522140217.GS32248@dhcp231-156.rdu.redhat.com> References: <1274461422-18433-1-git-send-email-josef@redhat.com> <1274461422-18433-3-git-send-email-josef@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: Josef Bacik , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, akpm@linux-foundation.org To: Mike Fedyk Return-path: In-Reply-To: List-ID: On Fri, May 21, 2010 at 06:47:36PM -0700, Mike Fedyk wrote: > On Fri, May 21, 2010 at 10:03 AM, Josef Bacik wrot= e: > > Btrfs cannot handle having logically non-contiguous requests submit= ted. =A0For > > example if you have > > > > Logical: =A0[0-4095][HOLE][8192-12287] > > Physical: [0-4095] =A0 =A0 =A0[4096-8191] > > > > Normally the DIO code would put these into the same BIO's. =A0The p= roblem is we > > need to know exactly what offset is associated with what BIO so we = can do our > > checksumming and unlocking properly, so putting them in the same BI= O doesn't > > work. =A0So add another check where we submit the current BIO if th= e physical > > blocks are not contigous OR the logical blocks are not contiguous. > > > > Signed-off-by: Josef Bacik > > --- > > > > V1->V2 > > -Be more verbose in the in-code comment > > > > =A0fs/direct-io.c | =A0 20 ++++++++++++++++++-- > > =A01 files changed, 18 insertions(+), 2 deletions(-) > > >=20 > Btrfs has been pretty much self-contained (working well compiled > against 2.6.32 for example). Is there a way that this wouldn't just > start silently breaking for people compiling the latest btrfs with > dkms against older kernels? Nope, you have to have these generic patches for DIO to work, so buildi= ng btrfs like this will stop working with earlier kernels. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html