From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 17 Apr 2019 15:05:27 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20190417140527.GE2839@work-vm> References: <20190416190858.16833-1-bo.liu@linux.alibaba.com> <20190416190858.16833-5-bo.liu@linux.alibaba.com> <20190417131848.GC2839@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] [PATCH 4/4] virtiofsd: use fallocate(2) instead posix_fallocate(3) List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Miklos Szeredi Cc: virtio-fs@redhat.com * Miklos Szeredi (mszeredi@redhat.com) wrote: > On Wed, Apr 17, 2019 at 3:18 PM Dr. David Alan Gilbert > wrote: > > > > * Liu Bo (bo.liu@linux.alibaba.com) wrote: > > > From: Xiaoguang Wang > > > > > > This is because posix_fallocate(3) does not support FALLOC_FL_KEEP_SIZE > > > and FALLOC_FL_PUNCH_HOLE. Our underlying host filesystem is ext4 and > > > ext4 supports FALLOC_FL_KEEP_SIZE and FALLOC_FL_PUNCH_HOLE well, so > > > this change will be ok. > > > > > > Signed-off-by: Xiaoguang Wang > > > > We need to check what 'fuse' expects - is it defined what > > fallocate features it has, and what the semantics are? > > The patch looks good to me. > > Fuse (the kernel part) supports FALLOC_FL_KEEP_SIZE and > FALLOC_FL_PUNCH_HOLE, but returns EOPNOTSUPP for any other flag. > > Even if, at a later time, fuse starts supporting additional fallocate > flags, then the passthrough implementation calling fallocate(2) should > be fine. OK, so then I'll take this patch; would it make sense for it to be sent to upstream fuse? Dave > Thanks, > Miklos -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK