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authorEdgar Kaziakhmedov <edgar.kaziakhmedov@virtuozzo.com>2018-01-12 12:01:22 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2018-01-22 14:02:33 +0000
commitbcbb3866da19cce4360c828b6ec1c2a137757927 (patch)
treea086d0f3829c7b0b37238b06e4eeeb411d55a57f /block
parent908b1c848e57ef14f17a5540e11aa9eb16219d66 (diff)
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block/parallels: add backing support to readv/writev
Since parallels format supports backing files, refine readv/writev (allocate_clusters) to redirect read/write requests to a backing file (if cluster is not available in the current bs). Signed-off-by: Edgar Kaziakhmedov <edgar.kaziakhmedov@virtuozzo.com> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Denis V. Lunev <den@openvz.org> Signed-off-by: Klim Kireev <klim.kireev@virtuozzo.com> Message-id: 20180112090122.1702-6-klim.kireev@virtuozzo.com CC: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/parallels.c50
1 files changed, 44 insertions, 6 deletions
diff --git a/block/parallels.c b/block/parallels.c
index 7a8e8b0..d380208 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -142,6 +142,7 @@ static int64_t block_status(BDRVParallelsState *s, int64_t sector_num,
static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
+ int ret;
BDRVParallelsState *s = bs->opaque;
int64_t pos, space, idx, to_allocate, i, len;
@@ -170,7 +171,6 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
return len;
}
if (s->data_end + space > (len >> BDRV_SECTOR_BITS)) {
- int ret;
space += s->prealloc_size;
if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE) {
ret = bdrv_pwrite_zeroes(bs->file,
@@ -186,6 +186,37 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
}
}
+ /* Try to read from backing to fill empty clusters
+ * FIXME: 1. previous write_zeroes may be redundant
+ * 2. most of data we read from backing will be rewritten by
+ * parallels_co_writev. On aligned-to-cluster write we do not need
+ * this read at all.
+ * 3. it would be good to combine write of data from backing and new
+ * data into one write call */
+ if (bs->backing) {
+ int64_t nb_cow_sectors = to_allocate * s->tracks;
+ int64_t nb_cow_bytes = nb_cow_sectors << BDRV_SECTOR_BITS;
+ QEMUIOVector qiov;
+ struct iovec iov = {
+ .iov_len = nb_cow_bytes,
+ .iov_base = qemu_blockalign(bs, nb_cow_bytes)
+ };
+ qemu_iovec_init_external(&qiov, &iov, 1);
+
+ ret = bdrv_co_readv(bs->backing, idx * s->tracks, nb_cow_sectors,
+ &qiov);
+ if (ret < 0) {
+ qemu_vfree(iov.iov_base);
+ return ret;
+ }
+
+ ret = bdrv_co_writev(bs->file, s->data_end, nb_cow_sectors, &qiov);
+ qemu_vfree(iov.iov_base);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
for (i = 0; i < to_allocate; i++) {
s->bat_bitmap[idx + i] = cpu_to_le32(s->data_end / s->off_multiplier);
s->data_end += s->tracks;
@@ -309,12 +340,19 @@ static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
nbytes = n << BDRV_SECTOR_BITS;
+ qemu_iovec_reset(&hd_qiov);
+ qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
+
if (position < 0) {
- qemu_iovec_memset(qiov, bytes_done, 0, nbytes);
+ if (bs->backing) {
+ ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
+ if (ret < 0) {
+ break;
+ }
+ } else {
+ qemu_iovec_memset(&hd_qiov, 0, 0, nbytes);
+ }
} else {
- qemu_iovec_reset(&hd_qiov);
- qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
-
ret = bdrv_co_readv(bs->file, position, n, &hd_qiov);
if (ret < 0) {
break;
@@ -748,7 +786,7 @@ static BlockDriver bdrv_parallels = {
.bdrv_co_flush_to_os = parallels_co_flush_to_os,
.bdrv_co_readv = parallels_co_readv,
.bdrv_co_writev = parallels_co_writev,
-
+ .supports_backing = true,
.bdrv_create = parallels_create,
.bdrv_check = parallels_check,
.create_opts = &parallels_create_opts,