From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34769) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YH4JE-0008Tu-8o for qemu-devel@nongnu.org; Fri, 30 Jan 2015 00:40:01 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YH4JA-0004uq-SD for qemu-devel@nongnu.org; Fri, 30 Jan 2015 00:40:00 -0500 Received: from mx2.parallels.com ([199.115.105.18]:46897) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YH4JA-0004ai-NK for qemu-devel@nongnu.org; Fri, 30 Jan 2015 00:39:56 -0500 Message-ID: <54CB18F0.3020700@openvz.org> Date: Fri, 30 Jan 2015 08:38:56 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1422470338-20465-1-git-send-email-den@openvz.org> <1422470338-20465-7-git-send-email-den@openvz.org> <54CAB927.4010006@redhat.com> In-Reply-To: <54CAB927.4010006@redhat.com> 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: Max Reitz Cc: Kevin Wolf , Fam Zheng , Peter Lieven , qemu-devel@nongnu.org, Stefan Hajnoczi On 30/01/15 01:50, Max Reitz wrote: > 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 OK. No problem. I do not think that it is ever possible, but why not? I will reorder these patches in the patchset to minimize changes.