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[Qemu-devel] [PATCH 3/4] block: Introduce bdrv_pwritev() for qcow2_save_
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 3/4] block: Introduce bdrv_pwritev() for qcow2_save_vmstate |
Date: |
Fri, 5 Apr 2013 21:27:55 +0200 |
Directly pass the QEMUIOVector on instead of linearising it.
Signed-off-by: Kevin Wolf <address@hidden>
---
block.c | 80 +++++++++++++++++++++++++++++++++++++--------------
block/qcow2.c | 8 +-----
include/block/block.h | 2 ++
3 files changed, 61 insertions(+), 29 deletions(-)
diff --git a/block.c b/block.c
index ab1883e..3777810 100644
--- a/block.c
+++ b/block.c
@@ -2134,27 +2134,21 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
}
/*
- * Process a synchronous request using coroutines
+ * Process a vectored synchronous request using coroutines
*/
-static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
- int nb_sectors, bool is_write)
+static int bdrv_rwv_co(BlockDriverState *bs, int64_t sector_num,
+ QEMUIOVector *qiov, bool is_write)
{
- QEMUIOVector qiov;
- struct iovec iov = {
- .iov_base = (void *)buf,
- .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
- };
Coroutine *co;
RwCo rwco = {
.bs = bs,
.sector_num = sector_num,
- .nb_sectors = nb_sectors,
- .qiov = &qiov,
+ .nb_sectors = qiov->size >> BDRV_SECTOR_BITS,
+ .qiov = qiov,
.is_write = is_write,
.ret = NOT_DONE,
};
-
- qemu_iovec_init_external(&qiov, &iov, 1);
+ assert((qiov->size & (BDRV_SECTOR_SIZE - 1)) == 0);
/**
* In sync call context, when the vcpu is blocked, this throttling timer
@@ -2180,6 +2174,22 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t
sector_num, uint8_t *buf,
return rwco.ret;
}
+/*
+ * Process a synchronous request using coroutines
+ */
+static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
+ int nb_sectors, bool is_write)
+{
+ QEMUIOVector qiov;
+ struct iovec iov = {
+ .iov_base = (void *)buf,
+ .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
+ };
+
+ qemu_iovec_init_external(&qiov, &iov, 1);
+ return bdrv_rwv_co(bs, sector_num, &qiov, is_write);
+}
+
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
@@ -2213,6 +2223,11 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num,
return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true);
}
+int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov)
+{
+ return bdrv_rwv_co(bs, sector_num, qiov, true);
+}
+
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count1)
{
@@ -2258,15 +2273,15 @@ int bdrv_pread(BlockDriverState *bs, int64_t offset,
return count1;
}
-int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
- const void *buf, int count1)
+int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov)
{
uint8_t tmp_buf[BDRV_SECTOR_SIZE];
int len, nb_sectors, count;
int64_t sector_num;
int ret;
- count = count1;
+ count = qiov->size;
+
/* first write to align to sector start */
len = (BDRV_SECTOR_SIZE - offset) & (BDRV_SECTOR_SIZE - 1);
if (len > count)
@@ -2275,24 +2290,32 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
if (len > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
- memcpy(tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)), buf, len);
+ qemu_iovec_to_buf(qiov, 0, tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)),
+ len);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
count -= len;
if (count == 0)
- return count1;
+ return qiov->size;
sector_num++;
- buf += len;
}
/* write the sectors "in place" */
nb_sectors = count >> BDRV_SECTOR_BITS;
if (nb_sectors > 0) {
- if ((ret = bdrv_write(bs, sector_num, buf, nb_sectors)) < 0)
+ QEMUIOVector qiov_inplace;
+
+ qemu_iovec_init(&qiov_inplace, qiov->niov);
+ qemu_iovec_concat(&qiov_inplace, qiov, len,
+ nb_sectors << BDRV_SECTOR_BITS);
+ ret = bdrv_writev(bs, sector_num, &qiov_inplace);
+ qemu_iovec_destroy(&qiov_inplace);
+ if (ret < 0) {
return ret;
+ }
+
sector_num += nb_sectors;
len = nb_sectors << BDRV_SECTOR_BITS;
- buf += len;
count -= len;
}
@@ -2300,11 +2323,24 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
if (count > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
- memcpy(tmp_buf, buf, count);
+ qemu_iovec_to_buf(qiov, qiov->size - count, tmp_buf, count);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
}
- return count1;
+ return qiov->size;
+}
+
+int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
+ const void *buf, int count1)
+{
+ QEMUIOVector qiov;
+ struct iovec iov = {
+ .iov_base = (void *) buf,
+ .iov_len = count1,
+ };
+
+ qemu_iovec_init_external(&qiov, &iov, 1);
+ return bdrv_pwritev(bs, offset, &qiov);
}
/*
diff --git a/block/qcow2.c b/block/qcow2.c
index 3dff968..132ff40 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1658,18 +1658,12 @@ static int qcow2_save_vmstate(BlockDriverState *bs,
QEMUIOVector *qiov,
BDRVQcowState *s = bs->opaque;
int growable = bs->growable;
int ret;
- void *buf;
-
- buf = qemu_blockalign(bs, qiov->size);
- qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
bs->growable = 1;
- ret = bdrv_pwrite(bs, qcow2_vm_state_offset(s) + pos, buf, qiov->size);
+ ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
bs->growable = growable;
- qemu_vfree(buf);
-
return ret;
}
diff --git a/include/block/block.h b/include/block/block.h
index e5fc566..ebd9512 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -166,10 +166,12 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t
sector_num,
uint8_t *buf, int nb_sectors);
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
+int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov);
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count);
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count);
+int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov);
int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
const void *buf, int count);
int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
--
1.8.1.4
Re: [Qemu-devel] [PATCH 0/4] block: Vectored bdrv_writev_vmstate, Stefan Hajnoczi, 2013/04/09