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[Qemu-devel] [PATCH v2 5/5] vmdk: add bdrv_co_write_zeroes
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH v2 5/5] vmdk: add bdrv_co_write_zeroes |
Date: |
Mon, 22 Apr 2013 10:07:59 +0800 |
Use special offset to write zeroes efficiently, when zeroed-grain GTE is
available. If zero-write an allocated cluster, cluster is leaked because
its offset pointer is overwritten by "0x1".
Signed-off-by: Fam Zheng <address@hidden>
---
block/vmdk.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 63 insertions(+), 19 deletions(-)
diff --git a/block/vmdk.c b/block/vmdk.c
index 632689b..7475090 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -814,6 +814,7 @@ static int get_whole_cluster(BlockDriverState *bs,
static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data)
{
/* update L2 table */
+ m_data->l2_offset = extent->l1_table[m_data->l1_index];
if (bdrv_pwrite_sync(
extent->file,
((int64_t)m_data->l2_offset * 512)
@@ -905,6 +906,12 @@ static int get_cluster_offset(BlockDriverState *bs,
l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;
*cluster_offset = le32_to_cpu(l2_table[l2_index]);
+ if (m_data) {
+ m_data->valid = 1;
+ m_data->l1_index = l1_index;
+ m_data->l2_index = l2_index;
+ m_data->offset = cpu_to_le32(*cluster_offset);
+ }
if (extent->has_zero_grain && *cluster_offset == VMDK_GTE_ZEROED) {
zeroed = true;
}
@@ -939,10 +946,6 @@ static int get_cluster_offset(BlockDriverState *bs,
if (m_data) {
m_data->offset = tmp;
- m_data->l1_index = l1_index;
- m_data->l2_index = l2_index;
- m_data->l2_offset = l2_offset;
- m_data->valid = 1;
}
}
*cluster_offset <<= 9;
@@ -1165,8 +1168,16 @@ static coroutine_fn int vmdk_co_read(BlockDriverState
*bs, int64_t sector_num,
return ret;
}
+/**
+ * params:
+ * - zeroed: buf is ignored (data is zero), use zeroed_grain GTE
+ * feature if possible, otherwise return -ENOTSUP.
+ * - zero_dry_run: used for zeroed == true only, don't update L2 table, just
+ * try if it's supported
+ */
static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
- const uint8_t *buf, int nb_sectors)
+ const uint8_t *buf, int nb_sectors,
+ bool zeroed, bool zero_dry_run)
{
BDRVVmdkState *s = bs->opaque;
VmdkExtent *extent = NULL;
@@ -1212,7 +1223,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t
sector_num,
&cluster_offset);
}
}
- if (ret) {
+ if (ret == VMDK_ERROR) {
return -EINVAL;
}
extent_begin_sector = extent->end_sector - extent->sectors;
@@ -1222,17 +1233,34 @@ static int vmdk_write(BlockDriverState *bs, int64_t
sector_num,
if (n > nb_sectors) {
n = nb_sectors;
}
-
- ret = vmdk_write_extent(extent,
- cluster_offset, index_in_cluster * 512,
- buf, n, sector_num);
- if (ret) {
- return ret;
- }
- if (m_data.valid) {
- /* update L2 tables */
- if (vmdk_L2update(extent, &m_data) == -1) {
- return -EIO;
+ if (zeroed) {
+ /* Do zeroed write, buf is ignored */
+ if (extent->has_zero_grain &&
+ index_in_cluster == 0 &&
+ n >= extent->cluster_sectors) {
+ n = extent->cluster_sectors;
+ if (!zero_dry_run) {
+ m_data.offset = cpu_to_le32(VMDK_GTE_ZEROED);
+ /* update L2 tables */
+ if (vmdk_L2update(extent, &m_data) == -1) {
+ return -EIO;
+ }
+ }
+ } else {
+ return -ENOTSUP;
+ }
+ } else {
+ ret = vmdk_write_extent(extent,
+ cluster_offset, index_in_cluster * 512,
+ buf, n, sector_num);
+ if (ret) {
+ return ret;
+ }
+ if (m_data.valid) {
+ /* update L2 tables */
+ if (vmdk_L2update(extent, &m_data) == -1) {
+ return -EIO;
+ }
}
}
nb_sectors -= n;
@@ -1258,7 +1286,22 @@ static coroutine_fn int vmdk_co_write(BlockDriverState
*bs, int64_t sector_num,
int ret;
BDRVVmdkState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
- ret = vmdk_write(bs, sector_num, buf, nb_sectors);
+ ret = vmdk_write(bs, sector_num, buf, nb_sectors, false, false);
+ qemu_co_mutex_unlock(&s->lock);
+ return ret;
+}
+
+static int coroutine_fn vmdk_co_write_zeroes(BlockDriverState *bs,
+ int64_t sector_num,
+ int nb_sectors)
+{
+ int ret;
+ BDRVVmdkState *s = bs->opaque;
+ qemu_co_mutex_lock(&s->lock);
+ ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, true);
+ if (!ret) {
+ ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, false);
+ }
qemu_co_mutex_unlock(&s->lock);
return ret;
}
@@ -1290,7 +1333,7 @@ static int vmdk_create_extent(const char *filename,
int64_t filesize,
header.version = zeroed_grain ? 2 : 1;
header.flags = VMDK4_FLAG_RGD | VMDK4_FLAG_NL_DETECT
| (compress ? VMDK4_FLAG_COMPRESS | VMDK4_FLAG_MARKER : 0)
- | (zeroed_grain ? VMDK4_FLAG_ZG : 0);
+ | (zeroed_grain ? VMDK4_FLAG_ZERO_GRAIN : 0);
header.compressAlgorithm = compress ? VMDK4_COMPRESSION_DEFLATE : 0;
header.capacity = filesize / 512;
header.granularity = 128;
@@ -1738,6 +1781,7 @@ static BlockDriver bdrv_vmdk = {
.bdrv_reopen_prepare = vmdk_reopen_prepare,
.bdrv_read = vmdk_co_read,
.bdrv_write = vmdk_co_write,
+ .bdrv_co_write_zeroes = vmdk_co_write_zeroes,
.bdrv_close = vmdk_close,
.bdrv_create = vmdk_create,
.bdrv_co_flush_to_disk = vmdk_co_flush,
--
1.8.1.4