From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 29 Sep 2016 13:35:46 -0700 From: "Darrick J. Wong" To: Bart Van Assche Cc: "axboe@kernel.dk" , "akpm@linux-foundation.org" , "hch@infradead.org" , "tytso@mit.edu" , "martin.petersen@oracle.com" , "snitzer@redhat.com" , "linux-api@vger.kernel.org" , "bfoster@redhat.com" , "xfs@oss.sgi.com" , "linux-block@vger.kernel.org" , "dm-devel@redhat.com" , "linux-fsdevel@vger.kernel.org" Subject: Re: [PATCH v2 3/3] block: implement (some of) fallocate for block devices Message-ID: <20160929203545.GF14092@birch.djwong.org> References: <147510957066.8940.13803086684642725401.stgit@birch.djwong.org> <147510959149.8940.2897845352082568677.stgit@birch.djwong.org> <20160929021900.GA4901@birch.djwong.org> <423d057c-d2cc-9039-d8ee-c6526be3ae46@sandisk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <423d057c-d2cc-9039-d8ee-c6526be3ae46@sandisk.com> List-ID: On Thu, Sep 29, 2016 at 01:08:57PM -0700, Bart Van Assche wrote: > On 09/28/2016 07:19 PM, Darrick J. Wong wrote: > >After much discussion, it seems that the fallocate feature flag > >FALLOC_FL_ZERO_RANGE maps nicely to SCSI WRITE SAME; and the feature > >FALLOC_FL_PUNCH_HOLE maps nicely to the devices that have been > >whitelisted for zeroing SCSI UNMAP. Punch still requires that > >FALLOC_FL_KEEP_SIZE is set. A length that goes past the end of the > >device will be clamped to the device size if KEEP_SIZE is set; or will > >return -EINVAL if not. Both start and length must be aligned to the > >device's logical block size. > > > >Since the semantics of fallocate are fairly well established already, > >wire up the two pieces. The other fallocate variants (collapse range, > >insert range, and allocate blocks) are not supported. > > For the FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE > case, it's probably safer not to try to send a discard to block devices that > do not support discard in order not to hit block driver bugs. But that's > something we can still discuss later. Hence: I'll just change it to check the queue flags and post a new revision. At this point I might as well repost the whole thing to reflect the reviewed-bys. --D > Reviewed-by: Bart Van Assche