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[Qemu-devel] [PATCH v3 6/6] vmdk: add bdrv_co_write_zeroes
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH v3 6/6] vmdk: add bdrv_co_write_zeroes |
Date: |
Wed, 24 Apr 2013 20:44:35 +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 | 77 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 63 insertions(+), 14 deletions(-)
diff --git a/block/vmdk.c b/block/vmdk.c
index 16e1417..90cb071 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -905,6 +905,13 @@ 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 = *cluster_offset;
+ m_data->l2_offset = extent->l1_table[m_data->l1_index];
+ }
if (extent->has_zero_grain && *cluster_offset == VMDK_GTE_ZEROED) {
zeroed = true;
}
@@ -1165,8 +1172,17 @@ static coroutine_fn int vmdk_co_read(BlockDriverState
*bs, int64_t sector_num,
return ret;
}
+/**
+ * vmdk_write:
+ * @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
+ *
+ * Returns: error code with 0 for success.
+ */
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 +1228,7 @@ 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 +1238,34 @@ 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) != VMDK_OK) {
+ 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) != VMDK_OK) {
+ return -EIO;
+ }
}
}
nb_sectors -= n;
@@ -1258,7 +1291,22 @@ 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;
}
@@ -1738,6 +1786,7 @@ 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
- [Qemu-devel] [PATCH v3 0/6] vmdk: zeroed-grain GTE support, Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 1/6] vmdk: named return code., Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 3/6] vmdk: Add option to create zeroed-grain image, Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 4/6] vmdk: change magic number to macro, Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 2/6] vmdk: add support for “zeroed‐grain” GTE, Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 5/6] vmdk: store fields of VmdkMetaData in cpu endian, Fam Zheng, 2013/04/24
- [Qemu-devel] [PATCH v3 6/6] vmdk: add bdrv_co_write_zeroes,
Fam Zheng <=
- Re: [Qemu-devel] [PATCH v3 0/6] vmdk: zeroed-grain GTE support, Stefan Hajnoczi, 2013/04/25