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push down vector linearization to posix-aio-compat.c (Christoph Hellwig)
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Make all AIO requests vectored and defer linearization until the actual
I/O thread.  This prepares for using native preadv/pwritev.

Also enables asynchronous direct I/O by handling that case in the I/O thread.

Qcow and qcow2 propably want to be adopted to directly deal with multi-segment
requests, but that can be implemented later.


Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Anthony Liguori <[email protected]>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7020 c046a42c-6fe2-441c-8c8c-71466251a162
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aliguori committed Apr 7, 2009
1 parent c87c067 commit f141eaf
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Showing 7 changed files with 317 additions and 284 deletions.
84 changes: 51 additions & 33 deletions block-qcow.c
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Original file line number Diff line number Diff line change
Expand Up @@ -525,7 +525,9 @@ static int qcow_write(BlockDriverState *bs, int64_t sector_num,
typedef struct QCowAIOCB {
BlockDriverAIOCB common;
int64_t sector_num;
QEMUIOVector *qiov;
uint8_t *buf;
void *orig_buf;
int nb_sectors;
int n;
uint64_t cluster_offset;
Expand All @@ -543,12 +545,8 @@ static void qcow_aio_read_cb(void *opaque, int ret)
int index_in_cluster;

acb->hd_aiocb = NULL;
if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
if (ret < 0)
goto done;

redo:
/* post process the read buffer */
Expand All @@ -570,9 +568,8 @@ static void qcow_aio_read_cb(void *opaque, int ret)

if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
ret = 0;
goto done;
}

/* prepare next AIO request */
Expand All @@ -592,7 +589,7 @@ static void qcow_aio_read_cb(void *opaque, int ret)
acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num,
&acb->hd_qiov, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
goto done;
} else {
/* Note: in this case, no need to wait */
memset(acb->buf, 0, 512 * acb->n);
Expand All @@ -601,14 +598,14 @@ static void qcow_aio_read_cb(void *opaque, int ret)
} else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
if (decompress_cluster(s, acb->cluster_offset) < 0)
goto fail;
goto done;
memcpy(acb->buf,
s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
goto redo;
} else {
if ((acb->cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
goto done;
}
acb->hd_iov.iov_base = acb->buf;
acb->hd_iov.iov_len = acb->n * 512;
Expand All @@ -617,12 +614,22 @@ static void qcow_aio_read_cb(void *opaque, int ret)
(acb->cluster_offset >> 9) + index_in_cluster,
&acb->hd_qiov, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
goto done;
}

return;

done:
if (acb->qiov->niov > 1) {
qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
qemu_vfree(acb->orig_buf);
}
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
}

static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors,
static BlockDriverAIOCB *qcow_aio_readv(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
QCowAIOCB *acb;
Expand All @@ -632,7 +639,11 @@ static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
return NULL;
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->buf = buf;
acb->qiov = qiov;
if (qiov->niov > 1)
acb->buf = acb->orig_buf = qemu_memalign(512, qiov->size);
else
acb->buf = qiov->iov->iov_base;
acb->nb_sectors = nb_sectors;
acb->n = 0;
acb->cluster_offset = 0;
Expand All @@ -652,22 +663,17 @@ static void qcow_aio_write_cb(void *opaque, int ret)

acb->hd_aiocb = NULL;

if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
if (ret < 0)
goto done;

acb->nb_sectors -= acb->n;
acb->sector_num += acb->n;
acb->buf += acb->n * 512;

if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
ret = 0;
goto done;
}

index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
Expand All @@ -679,14 +685,14 @@ static void qcow_aio_write_cb(void *opaque, int ret)
index_in_cluster + acb->n);
if (!cluster_offset || (cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
goto done;
}
if (s->crypt_method) {
if (!acb->cluster_data) {
acb->cluster_data = qemu_mallocz(s->cluster_size);
if (!acb->cluster_data) {
ret = -ENOMEM;
goto fail;
goto done;
}
}
encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
Expand All @@ -704,11 +710,18 @@ static void qcow_aio_write_cb(void *opaque, int ret)
&acb->hd_qiov, acb->n,
qcow_aio_write_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
goto done;
return;

done:
if (acb->qiov->niov > 1)
qemu_vfree(acb->orig_buf);
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
}

static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
int64_t sector_num, const uint8_t *buf, int nb_sectors,
static BlockDriverAIOCB *qcow_aio_writev(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
BDRVQcowState *s = bs->opaque;
Expand All @@ -721,7 +734,12 @@ static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
return NULL;
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->buf = (uint8_t *)buf;
acb->qiov = qiov;
if (qiov->niov > 1) {
acb->buf = acb->orig_buf = qemu_memalign(512, qiov->size);
qemu_iovec_to_buffer(qiov, acb->buf);
} else
acb->buf = qiov->iov->iov_base;
acb->nb_sectors = nb_sectors;
acb->n = 0;

Expand Down Expand Up @@ -909,8 +927,8 @@ BlockDriver bdrv_qcow = {
.bdrv_is_allocated = qcow_is_allocated,
.bdrv_set_key = qcow_set_key,
.bdrv_make_empty = qcow_make_empty,
.bdrv_aio_read = qcow_aio_read,
.bdrv_aio_write = qcow_aio_write,
.bdrv_aio_readv = qcow_aio_readv,
.bdrv_aio_writev = qcow_aio_writev,
.bdrv_aio_cancel = qcow_aio_cancel,
.aiocb_size = sizeof(QCowAIOCB),
.bdrv_write_compressed = qcow_write_compressed,
Expand Down
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