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vdi: basic conversion to coroutines 

Even a basic conversion changing the bdrv_aio_readv/bdrv_aio_writev calls
to bdrv_co_readv/bdrv_co_writev, and callbacks to goto statements can
eliminate a lot of code.  This is because error handling is simplified
and indirections through bottom halves can go away.

After this patch, I/O to the underlying file already happens via
coroutines, but the code still looks a lot like if asynchronous I/O was
being used.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-03-19 18:07:45 +01:00 committed by Kevin Wolf
parent 1fc86bf963
commit 3d46a75aa5
1 changed files with 37 additions and 121 deletions
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158
block/vdi.c
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@ -160,7 +160,6 @@ typedef struct {
void *orig_buf; void *orig_buf;
bool is_write; bool is_write;
int header_modified; int header_modified;
BlockDriverAIOCB *hd_aiocb;
struct iovec hd_iov; struct iovec hd_iov;
QEMUIOVector hd_qiov; QEMUIOVector hd_qiov;
QEMUBH *bh; QEMUBH *bh;
@ -489,33 +488,19 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs,
return VDI_IS_ALLOCATED(bmap_entry); return VDI_IS_ALLOCATED(bmap_entry);
} }
static void vdi_aio_cancel(BlockDriverAIOCB *blockacb)
{
/* TODO: This code is untested. How can I get it executed? */
VdiAIOCB *acb = container_of(blockacb, VdiAIOCB, common);
logout("\n");
if (acb->hd_aiocb) {
bdrv_aio_cancel(acb->hd_aiocb);
}
qemu_aio_release(acb);
}
static AIOPool vdi_aio_pool = { static AIOPool vdi_aio_pool = {
.aiocb_size = sizeof(VdiAIOCB), .aiocb_size = sizeof(VdiAIOCB),
.cancel = vdi_aio_cancel,
}; };
static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num, static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, int nb_sectors, QEMUIOVector *qiov, int nb_sectors, int is_write)
BlockDriverCompletionFunc *cb, void *opaque, int is_write)
{ {
VdiAIOCB *acb; VdiAIOCB *acb;
logout("%p, %" PRId64 ", %p, %d, %p, %p, %d\n", logout("%p, %" PRId64 ", %p, %d, %p, %p, %d\n",
bs, sector_num, qiov, nb_sectors, cb, opaque, is_write); bs, sector_num, qiov, nb_sectors, is_write);
acb = qemu_aio_get(&vdi_aio_pool, bs, cb, opaque); acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);
acb->hd_aiocb = NULL;
acb->sector_num = sector_num; acb->sector_num = sector_num;
acb->qiov = qiov; acb->qiov = qiov;
acb->is_write = is_write; acb->is_write = is_write;
@ -538,42 +523,7 @@ static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
return acb; return acb;
} }
static int vdi_schedule_bh(QEMUBHFunc *cb, VdiAIOCB *acb) static int vdi_aio_read_cb(void *opaque, int ret)
{
logout("\n");
if (acb->bh) {
return -EIO;
}
acb->bh = qemu_bh_new(cb, acb);
if (!acb->bh) {
return -EIO;
}
qemu_bh_schedule(acb->bh);
return 0;
}
static void vdi_aio_read_cb(void *opaque, int ret);
static void vdi_aio_write_cb(void *opaque, int ret);
static void vdi_aio_rw_bh(void *opaque)
{
VdiAIOCB *acb = opaque;
logout("\n");
qemu_bh_delete(acb->bh);
acb->bh = NULL;
if (acb->is_write) {
vdi_aio_write_cb(opaque, 0);
} else {
vdi_aio_read_cb(opaque, 0);
}
}
static void vdi_aio_read_cb(void *opaque, int ret)
{ {
VdiAIOCB *acb = opaque; VdiAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs; BlockDriverState *bs = acb->common.bs;
@ -585,12 +535,7 @@ static void vdi_aio_read_cb(void *opaque, int ret)
logout("%u sectors read\n", acb->n_sectors); logout("%u sectors read\n", acb->n_sectors);
acb->hd_aiocb = NULL; restart:
if (ret < 0) {
goto done;
}
acb->nb_sectors -= acb->n_sectors; acb->nb_sectors -= acb->n_sectors;
if (acb->nb_sectors == 0) { if (acb->nb_sectors == 0) {
@ -618,10 +563,7 @@ static void vdi_aio_read_cb(void *opaque, int ret)
if (!VDI_IS_ALLOCATED(bmap_entry)) { if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Block not allocated, return zeros, no need to wait. */ /* Block not allocated, return zeros, no need to wait. */
memset(acb->buf, 0, n_sectors * SECTOR_SIZE); memset(acb->buf, 0, n_sectors * SECTOR_SIZE);
ret = vdi_schedule_bh(vdi_aio_rw_bh, acb); ret = 0;
if (ret < 0) {
goto done;
}
} else { } else {
uint64_t offset = s->header.offset_data / SECTOR_SIZE + uint64_t offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors + (uint64_t)bmap_entry * s->block_sectors +
@ -629,41 +571,34 @@ static void vdi_aio_read_cb(void *opaque, int ret)
acb->hd_iov.iov_base = (void *)acb->buf; acb->hd_iov.iov_base = (void *)acb->buf;
acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE; acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
acb->hd_aiocb = bdrv_aio_readv(bs->file, offset, &acb->hd_qiov, ret = bdrv_co_readv(bs->file, offset, n_sectors, &acb->hd_qiov);
n_sectors, vdi_aio_read_cb, acb);
} }
return; if (ret >= 0) {
goto restart;
}
done: done:
if (acb->qiov->niov > 1) { if (acb->qiov->niov > 1) {
qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size); qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
qemu_vfree(acb->orig_buf); qemu_vfree(acb->orig_buf);
} }
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb); qemu_aio_release(acb);
return ret;
} }
static BlockDriverAIOCB *vdi_aio_readv(BlockDriverState *bs, static int vdi_co_readv(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
BlockDriverCompletionFunc *cb, void *opaque)
{ {
VdiAIOCB *acb; VdiAIOCB *acb;
int ret; int ret;
logout("\n"); logout("\n");
acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0); acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
ret = vdi_schedule_bh(vdi_aio_rw_bh, acb); ret = vdi_aio_read_cb(acb, 0);
if (ret < 0) { return ret;
if (acb->qiov->niov > 1) {
qemu_vfree(acb->orig_buf);
}
qemu_aio_release(acb);
return NULL;
} }
return &acb->common; static int vdi_aio_write_cb(void *opaque, int ret)
}
static void vdi_aio_write_cb(void *opaque, int ret)
{ {
VdiAIOCB *acb = opaque; VdiAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs; BlockDriverState *bs = acb->common.bs;
@ -673,12 +608,7 @@ static void vdi_aio_write_cb(void *opaque, int ret)
uint32_t sector_in_block; uint32_t sector_in_block;
uint32_t n_sectors; uint32_t n_sectors;
acb->hd_aiocb = NULL; restart:
if (ret < 0) {
goto done;
}
acb->nb_sectors -= acb->n_sectors; acb->nb_sectors -= acb->n_sectors;
acb->sector_num += acb->n_sectors; acb->sector_num += acb->n_sectors;
acb->buf += acb->n_sectors * SECTOR_SIZE; acb->buf += acb->n_sectors * SECTOR_SIZE;
@ -686,6 +616,7 @@ static void vdi_aio_write_cb(void *opaque, int ret)
if (acb->nb_sectors == 0) { if (acb->nb_sectors == 0) {
logout("finished data write\n"); logout("finished data write\n");
acb->n_sectors = 0; acb->n_sectors = 0;
ret = 0;
if (acb->header_modified) { if (acb->header_modified) {
VdiHeader *header = acb->block_buffer; VdiHeader *header = acb->block_buffer;
logout("now writing modified header\n"); logout("now writing modified header\n");
@ -696,10 +627,9 @@ static void vdi_aio_write_cb(void *opaque, int ret)
acb->hd_iov.iov_base = acb->block_buffer; acb->hd_iov.iov_base = acb->block_buffer;
acb->hd_iov.iov_len = SECTOR_SIZE; acb->hd_iov.iov_len = SECTOR_SIZE;
qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
acb->hd_aiocb = bdrv_aio_writev(bs->file, 0, &acb->hd_qiov, 1, ret = bdrv_co_writev(bs->file, 0, 1, &acb->hd_qiov);
vdi_aio_write_cb, acb); }
return; if (ret >= 0 && VDI_IS_ALLOCATED(acb->bmap_first)) {
} else if (VDI_IS_ALLOCATED(acb->bmap_first)) {
/* One or more new blocks were allocated. */ /* One or more new blocks were allocated. */
uint64_t offset; uint64_t offset;
uint32_t bmap_first; uint32_t bmap_first;
@ -722,11 +652,8 @@ static void vdi_aio_write_cb(void *opaque, int ret)
qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
logout("will write %u block map sectors starting from entry %u\n", logout("will write %u block map sectors starting from entry %u\n",
n_sectors, bmap_first); n_sectors, bmap_first);
acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov, ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
n_sectors, vdi_aio_write_cb, acb);
return;
} }
ret = 0;
goto done; goto done;
} }
@ -772,9 +699,7 @@ static void vdi_aio_write_cb(void *opaque, int ret)
acb->hd_iov.iov_base = (void *)block; acb->hd_iov.iov_base = (void *)block;
acb->hd_iov.iov_len = s->block_size; acb->hd_iov.iov_len = s->block_size;
qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &acb->hd_qiov);
&acb->hd_qiov, s->block_sectors,
vdi_aio_write_cb, acb);
} else { } else {
uint64_t offset = s->header.offset_data / SECTOR_SIZE + uint64_t offset = s->header.offset_data / SECTOR_SIZE +
(uint64_t)bmap_entry * s->block_sectors + (uint64_t)bmap_entry * s->block_sectors +
@ -782,39 +707,30 @@ static void vdi_aio_write_cb(void *opaque, int ret)
acb->hd_iov.iov_base = (void *)acb->buf; acb->hd_iov.iov_base = (void *)acb->buf;
acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE; acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1); qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov, ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
n_sectors, vdi_aio_write_cb, acb); }
if (ret >= 0) {
goto restart;
} }
return;
done: done:
if (acb->qiov->niov > 1) { if (acb->qiov->niov > 1) {
qemu_vfree(acb->orig_buf); qemu_vfree(acb->orig_buf);
} }
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb); qemu_aio_release(acb);
return ret;
} }
static BlockDriverAIOCB *vdi_aio_writev(BlockDriverState *bs, static int vdi_co_writev(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
BlockDriverCompletionFunc *cb, void *opaque)
{ {
VdiAIOCB *acb; VdiAIOCB *acb;
int ret; int ret;
logout("\n"); logout("\n");
acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1); acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 1);
ret = vdi_schedule_bh(vdi_aio_rw_bh, acb); ret = vdi_aio_write_cb(acb, 0);
if (ret < 0) { return ret;
if (acb->qiov->niov > 1) {
qemu_vfree(acb->orig_buf);
}
qemu_aio_release(acb);
return NULL;
}
return &acb->common;
} }
static int vdi_create(const char *filename, QEMUOptionParameter *options) static int vdi_create(const char *filename, QEMUOptionParameter *options)
@ -965,9 +881,9 @@ static BlockDriver bdrv_vdi = {
.bdrv_co_is_allocated = vdi_co_is_allocated, .bdrv_co_is_allocated = vdi_co_is_allocated,
.bdrv_make_empty = vdi_make_empty, .bdrv_make_empty = vdi_make_empty,
.bdrv_aio_readv = vdi_aio_readv, .bdrv_co_readv = vdi_co_readv,
#if defined(CONFIG_VDI_WRITE) #if defined(CONFIG_VDI_WRITE)
.bdrv_aio_writev = vdi_aio_writev, .bdrv_co_writev = vdi_co_writev,
#endif #endif
.bdrv_get_info = vdi_get_info, .bdrv_get_info = vdi_get_info,