From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58151) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGxus-000714-Va for qemu-devel@nongnu.org; Thu, 29 Jan 2015 17:50:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YGxup-00056O-Pl for qemu-devel@nongnu.org; Thu, 29 Jan 2015 17:50:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56597) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGxup-000560-Fz for qemu-devel@nongnu.org; Thu, 29 Jan 2015 17:50:23 -0500 Message-ID: <54CAB927.4010006@redhat.com> Date: Thu, 29 Jan 2015 17:50:15 -0500 From: Max Reitz MIME-Version: 1.0 References: <1422470338-20465-1-git-send-email-den@openvz.org> <1422470338-20465-7-git-send-email-den@openvz.org> In-Reply-To: <1422470338-20465-7-git-send-email-den@openvz.org> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/7] block/raw-posix: call plain fallocate in handle_aiocb_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" Cc: Kevin Wolf , Fam Zheng , Peter Lieven , qemu-devel@nongnu.org, Stefan Hajnoczi On 2015-01-28 at 13:38, Denis V. Lunev wrote: > There is a possibility that we are extending our image and thus writing > zeroes beyond the end of the file. In this case we do not need to care > about the hole to make sure that there is no data in the file under > this offset (pre-condition to fallocate(0) to work). We could simply call > fallocate(0). > > This improves the performance of writing zeroes even on really old > platforms which do not have even FALLOC_FL_PUNCH_HOLE. > > Before the patch do_fallocate was used when either > CONFIG_FALLOCATE_PUNCH_HOLE or CONFIG_FALLOCATE_ZERO_RANGE are defined. > Now the story is different. CONFIG_FALLOCATE is defined when Linux > fallocate is defined, posix_fallocate is completely different story > (CONFIG_POSIX_FALLOCATE). CONFIG_FALLOCATE is mandatory prerequite > for both CONFIG_FALLOCATE_PUNCH_HOLE and CONFIG_FALLOCATE_ZERO_RANGE > thus we are on the safe side. > > Signed-off-by: Denis V. Lunev > CC: Max Reitz > CC: Kevin Wolf > CC: Stefan Hajnoczi > CC: Peter Lieven > CC: Fam Zheng > --- > block/raw-posix.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 2e24829..3db911a 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -147,6 +147,7 @@ typedef struct BDRVRawState { > bool has_discard:1; > bool has_write_zeroes:1; > bool discard_zeroes:1; > + bool has_fallocate; > bool needs_alignment; > } BDRVRawState; > > @@ -452,6 +453,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, > } > if (S_ISREG(st.st_mode)) { > s->discard_zeroes = true; > + s->has_fallocate = true; > } > if (S_ISBLK(st.st_mode)) { > #ifdef BLKDISCARDZEROES > @@ -902,7 +904,7 @@ static int translate_err(int err) > return err; > } > > -#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_FALLOCATE_ZERO_RANGE) > +#ifdef CONFIG_FALLOCATE > static int do_fallocate(int fd, int mode, off_t offset, off_t len) > { > do { > @@ -980,6 +982,16 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) > } > #endif > > +#ifdef CONFIG_FALLOCATE > + if (s->has_fallocate && aiocb->aio_offset >= bdrv_getlength(aiocb->bs)) { > + int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes); > + if (ret == 0 || ret != -ENOTSUP) { > + return ret; > + } > + s->has_fallocate = false; > + } > +#endif > + > return -ENOTSUP; > } Now that you do have has_fallocate, I think you should be using it in patch 5 as well. So I think you should either you make this patch add it in the area touched by patch 5, or you introduce has_fallocate in patch 5 already and use it there. Max