From: Pavel Butsykin <pbutsy...@virtuozzo.com>
Added implementation of the qcow_co_write_compressed function that
will allow us to safely use compressed writes for the qcow from running
VMs.
Signed-off-by: Pavel Butsykin <pbutsy...@virtuozzo.com>
Signed-off-by: Denis V. Lunev <d...@openvz.org>
CC: Jeff Cody <jc...@redhat.com>
CC: Markus Armbruster <arm...@redhat.com>
CC: Eric Blake <ebl...@redhat.com>
CC: John Snow <js...@redhat.com>
CC: Stefan Hajnoczi <stefa...@redhat.com>
CC: Kevin Wolf <kw...@redhat.com>
---
block/qcow.c | 78 +++++++++++++++++++++++++++++++++++-------------------------
1 file changed, 45 insertions(+), 33 deletions(-)
diff --git a/block/qcow.c b/block/qcow.c
index d6dc1b0..80a4ce8 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -909,38 +909,37 @@ static int qcow_make_empty(BlockDriverState *bs)
/* XXX: put compressed sectors first, then all the cluster aligned
tables to avoid losing bytes in alignment */
-static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
- const uint8_t *buf, int nb_sectors)
+static coroutine_fn int
+qcow_co_write_compressed(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors, QEMUIOVector *qiov)
{
BDRVQcowState *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;
+ 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 = qcow_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);
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);
if (ret != 0) {
ret = -EINVAL;
goto fail;
@@ -962,28 +961,41 @@ static int qcow_write_compressed(BlockDriverState *bs,
int64_t sector_num,
deflateEnd(&strm);
if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
+ struct iovec iov = {
+ .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);
- if (ret < 0) {
- goto fail;
- }
- } else {
- cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
- out_len, 0, 0);
- if (cluster_offset == 0) {
- ret = -EIO;
- goto fail;
- }
-
- cluster_offset &= s->cluster_offset_mask;
- ret = bdrv_pwrite(bs->file->bs, cluster_offset, out_buf, out_len);
+ ret = qcow_co_writev(bs, sector_num, s->cluster_sectors, &hd_qiov);
if (ret < 0) {
goto fail;
}
+ goto success;
}
+ qemu_co_mutex_lock(&s->lock);
+ cluster_offset = get_cluster_offset(bs, sector_num << 9, 2, out_len, 0, 0);
+ qemu_co_mutex_unlock(&s->lock);
+ if (cluster_offset == 0) {
+ ret = -EIO;
+ goto fail;
+ }
+ cluster_offset &= s->cluster_offset_mask;
+
+ iov = (struct iovec) {
+ .iov_base = out_buf,
+ .iov_len = out_len,
+ };
+ qemu_iovec_init_external(&hd_qiov, &iov, 1);
+ ret = bdrv_co_pwritev(bs->file->bs, cluster_offset, out_len, &hd_qiov, 0);
+ if (ret < 0) {
+ goto fail;
+ }
+success:
ret = 0;
fail:
+ qemu_vfree(buf);
g_free(out_buf);
return ret;
}
@@ -1036,7 +1048,7 @@ static BlockDriver bdrv_qcow = {
.bdrv_set_key = qcow_set_key,
.bdrv_make_empty = qcow_make_empty,
- .bdrv_write_compressed = qcow_write_compressed,
+ .bdrv_co_write_compressed = qcow_co_write_compressed,
.bdrv_get_info = qcow_get_info,
.create_opts = &qcow_create_opts,
--
2.1.4
