From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45781) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHupC-0000c3-F0 for qemu-devel@nongnu.org; Tue, 28 Jun 2016 11:21:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bHup7-0005CW-9A for qemu-devel@nongnu.org; Tue, 28 Jun 2016 11:21:17 -0400 Received: from mail-db3on0135.outbound.protection.outlook.com ([157.55.234.135]:60032 helo=emea01-db3-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHup6-0005CP-Gs for qemu-devel@nongnu.org; Tue, 28 Jun 2016 11:21:13 -0400 References: <1464686130-12265-1-git-send-email-den@openvz.org> <1464686130-12265-4-git-send-email-den@openvz.org> <20160628113000.GD6800@noname.redhat.com> From: Pavel Butsykin Message-ID: <57729264.5030400@virtuozzo.com> Date: Tue, 28 Jun 2016 18:06:12 +0300 MIME-Version: 1.0 In-Reply-To: <20160628113000.GD6800@noname.redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 03/11] qcow2: add qcow2_co_write_compressed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , "Denis V. Lunev" Cc: qemu-devel@nongnu.org, Jeff Cody , Markus Armbruster , Eric Blake , John Snow , Stefan Hajnoczi On 28.06.2016 14:30, Kevin Wolf wrote: > Am 31.05.2016 um 11:15 hat Denis V. Lunev geschrieben: >> From: Pavel Butsykin >> >> Added implementation of the qcow2_co_write_compressed function that >> will allow us to safely use compressed writes for the qcow2 from running VMs. >> >> Signed-off-by: Pavel Butsykin >> Signed-off-by: Denis V. Lunev >> CC: Jeff Cody >> CC: Markus Armbruster >> CC: Eric Blake >> CC: John Snow >> CC: Stefan Hajnoczi >> CC: Kevin Wolf >> --- >> block/qcow2.c | 89 ++++++++++++++++++++++++++++++++++------------------------- >> 1 file changed, 52 insertions(+), 37 deletions(-) >> >> diff --git a/block/qcow2.c b/block/qcow2.c >> index c9306a7..38caa66 100644 >> --- a/block/qcow2.c >> +++ b/block/qcow2.c >> @@ -2535,13 +2535,16 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset) >> >> /* XXX: put compressed sectors first, then all the cluster aligned >> tables to avoid losing bytes in alignment */ >> -static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, >> - const uint8_t *buf, int nb_sectors) >> +static coroutine_fn int >> +qcow2_co_write_compressed(BlockDriverState *bs, int64_t sector_num, >> + int nb_sectors, QEMUIOVector *qiov) >> { >> BDRVQcow2State *s = bs->opaque; >> + QEMUIOVector hd_qiov; >> + struct iovec iov; >> z_stream strm; >> int ret, out_len; >> - uint8_t *out_buf; >> + uint8_t *buf, *out_buf; >> uint64_t cluster_offset; >> >> if (nb_sectors == 0) { >> @@ -2551,29 +2554,25 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, >> return bdrv_truncate(bs->file->bs, cluster_offset); >> } >> >> + buf = qemu_blockalign(bs, s->cluster_size); >> if (nb_sectors != s->cluster_sectors) { >> - ret = -EINVAL; >> - >> - /* Zero-pad last write if image size is not cluster aligned */ >> - if (sector_num + nb_sectors == bs->total_sectors && >> - nb_sectors < s->cluster_sectors) { >> - uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size); >> - memset(pad_buf, 0, s->cluster_size); >> - memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE); >> - ret = qcow2_write_compressed(bs, sector_num, >> - pad_buf, s->cluster_sectors); >> - qemu_vfree(pad_buf); >> + if (nb_sectors > s->cluster_sectors || >> + sector_num + nb_sectors != bs->total_sectors) >> + { >> + qemu_vfree(buf); >> + return -EINVAL; >> } >> - return ret; >> + /* Zero-pad last write if image size is not cluster aligned */ >> + memset(buf, 0, s->cluster_size); >> } >> + qemu_iovec_to_buf(qiov, 0, buf, qiov->size); > > This looks less related to the new interface, but more like an unrelated > (but still worthwhile) cleanup to avoid the recursion. > > Can we separate this out as a cleanup patch before this one? > We can :) > Also, the last parameter of qemu_iovec_to_buf() should be > s->cluster_size, it's the buffer size and not the qiov size. > Additionally, we may want to assert(qiov->size == s->cluster_size). It is not necessary, the qiov size can be less than s->cluster_size. In this case, the remaining part of the cluster is filled with zeros. > >> out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); >> >> /* best compression, small window, no zlib header */ >> memset(&strm, 0, sizeof(strm)); >> - ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, >> - Z_DEFLATED, -12, >> - 9, Z_DEFAULT_STRATEGY); >> + ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, >> + -12, 9, Z_DEFAULT_STRATEGY); > > Unrelated reformatting? Let's drop this, so the semantic changes in the > patch become more visible. > ok >> if (ret != 0) { >> ret = -EINVAL; >> goto fail; >> @@ -2595,34 +2594,50 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, >> deflateEnd(&strm); >> >> if (ret != Z_STREAM_END || out_len >= s->cluster_size) { >> + iov = (struct iovec) { >> + .iov_base = buf, >> + .iov_len = out_len, >> + }; >> + qemu_iovec_init_external(&hd_qiov, &iov, 1); >> /* could not compress: write normal cluster */ >> - ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors); >> + ret = qcow2_co_writev(bs, sector_num, s->cluster_sectors, &hd_qiov); > > Now that it's qcow2_co_pwritev(), you can probably just use the existing > qiov. > >> if (ret < 0) { >> goto fail; >> } >> - } else { >> - cluster_offset = qcow2_alloc_compressed_cluster_offset(bs, >> - sector_num << 9, out_len); >> - if (!cluster_offset) { >> - ret = -EIO; >> - goto fail; >> - } >> - cluster_offset &= s->cluster_offset_mask; >> + goto success; >> + } >> >> - ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len); >> - if (ret < 0) { >> - goto fail; >> - } >> + qemu_co_mutex_lock(&s->lock); >> + cluster_offset = \ > > That backslash isn't necessary. > I know it's just a marker. >> + qcow2_alloc_compressed_cluster_offset(bs, sector_num << 9, out_len); >> + if (!cluster_offset) { >> + qemu_co_mutex_unlock(&s->lock); >> + ret = -EIO; >> + goto fail; >> + } >> + cluster_offset &= s->cluster_offset_mask; > > Kevin >