From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43575) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGAjZ-0006wn-Dp for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:19:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YGAjU-0006pv-BO for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:19:29 -0500 Received: from mx2.parallels.com ([199.115.105.18]:58576) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGAjU-0006pR-6J for qemu-devel@nongnu.org; Tue, 27 Jan 2015 13:19:24 -0500 Message-ID: <54C7D6A1.6080500@openvz.org> Date: Tue, 27 Jan 2015 21:19:13 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1422366699-17473-1-git-send-email-den@openvz.org> <1422366699-17473-7-git-send-email-den@openvz.org> <54C7D19F.20408@redhat.com> In-Reply-To: <54C7D19F.20408@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 , Peter Lieven , Fam Zheng , qemu-devel@nongnu.org, Stefan Hajnoczi On 27/01/15 20:57, Max Reitz wrote: > On 2015-01-27 at 08:51, 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. >> >> Signed-off-by: Denis V. Lunev >> CC: Kevin Wolf >> CC: Stefan Hajnoczi >> CC: Peter Lieven >> CC: Fam Zheng >> --- >> block/raw-posix.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> diff --git a/block/raw-posix.c b/block/raw-posix.c >> index c039bef..fa05239 100644 >> --- a/block/raw-posix.c >> +++ b/block/raw-posix.c >> @@ -60,7 +60,7 @@ >> #define FS_NOCOW_FL 0x00800000 /* Do not cow >> file */ >> #endif >> #endif >> -#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || >> defined(CONFIG_FALLOCATE_ZERO_RANGE) >> +#ifdef CONFIG_FALLOCATE > > This change doesn't seem right; CONFIG_FALLOCATE is set if > posix_fallocate() is available, not for the Linux-specific fallocate() > from linux/falloc.h. > here is a check for fallocate and posix_fallocate in configure script # check for fallocate fallocate=no cat > $TMPC << EOF #include int main(void) { fallocate(0, 0, 0, 0); return 0; } EOF if compile_prog "" "" ; then fallocate=yes fi ... # check for posix_fallocate posix_fallocate=no cat > $TMPC << EOF #include int main(void) { posix_fallocate(0, 0, 0); return 0; } EOF if compile_prog "" "" ; then posix_fallocate=yes fi ... if test "$fallocate" = "yes" ; then echo "CONFIG_FALLOCATE=y" >> $config_host_mak fi ... if test "$posix_fallocate" = "yes" ; then echo "CONFIG_POSIX_FALLOCATE=y" >> $config_host_mak fi Thus my check looks correct to me. >> #include >> #endif >> #if defined (__FreeBSD__) || defined(__FreeBSD_kernel__) >> @@ -902,7 +902,7 @@ static int translate_err(int err) >> return err; >> } >> -#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || >> defined(CONFIG_FALLOCATE_ZERO_RANGE) >> +#ifdef CONFIG_FALLOCATE > > Same here. > >> static int do_fallocate(int fd, int mode, off_t offset, off_t len) >> { >> do { >> @@ -981,6 +981,12 @@ static ssize_t >> handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) >> } >> #endif >> +#ifdef CONFIG_FALLOCATE >> + if (aiocb->aio_offset >= aiocb->bs->total_sectors << >> BDRV_SECTOR_BITS) { >> + return do_fallocate(s->fd, 0, aiocb->aio_offset, >> aiocb->aio_nbytes); >> + } >> +#endif >> + > > This seems fine though, but as I've asked in patch 5: Do we want to > have a "has_fallocate"? > > Other than that, this is the first usage of bs->total_sectors in this > file; raw_co_get_block_status() does a similar check, but it uses > bdrv_getlength() instead. If bs->total_sectors is correct, > bdrv_getlength() will actually do nothing but return bs->total_sectors > * BDRV_SECTOR_SIZE; it will only do more (that is, update > bs->total_sectors) if it is not correct to use bs->total_sectors (and > I feel like it may not be correct because > BlockDriver.has_variable_length is true). > > Max > ok, will do