[Qemu-devel] [PATCH v2 0/7] vdi: convert to coroutines

[Qemu-devel] [PATCH v2 0/7] vdi: convert to coroutines

[Paolo Bonzini]

This squashes in the fix for GCC's uninitialized variables false positive.

Paolo Bonzini (7):
  vdi: basic conversion to coroutines
  vdi: move end-of-I/O handling at the end
  vdi: merge aio_read_cb and aio_write_cb into callers
  vdi: move aiocb fields to locals
  vdi: leave bounce buffering to block layer
  vdi: do not create useless iovecs
  vdi: change goto to loop

 block/vdi.c |  421 +++++++++++++++--------------------------------------------
 1 files changed, 108 insertions(+), 313 deletions(-)

-- 
1.7.7.6

[Qemu-devel] [PATCH v2 1/7] vdi: basic conversion to coroutines

[Paolo Bonzini]

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>
---
 block/vdi.c |  158 ++++++++++++++---------------------------------------------
 1 files changed, 37 insertions(+), 121 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 6a0011f..35edc90 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -160,7 +160,6 @@ typedef struct {
     void *orig_buf;
     bool is_write;
     int header_modified;
-    BlockDriverAIOCB *hd_aiocb;
     struct iovec hd_iov;
     QEMUIOVector hd_qiov;
     QEMUBH *bh;
@@ -489,33 +488,19 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs,
     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 = {
     .aiocb_size = sizeof(VdiAIOCB),
-    .cancel = vdi_aio_cancel,
 };
 
 static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
-        QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque, int is_write)
+        QEMUIOVector *qiov, int nb_sectors, int is_write)
 {
     VdiAIOCB *acb;
 
     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->hd_aiocb = NULL;
+    acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);
     acb->sector_num = sector_num;
     acb->qiov = qiov;
     acb->is_write = is_write;
@@ -538,42 +523,7 @@ static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
     return acb;
 }
 
-static int vdi_schedule_bh(QEMUBHFunc *cb, VdiAIOCB *acb)
-{
-    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)
+static int vdi_aio_read_cb(void *opaque, int ret)
 {
     VdiAIOCB *acb = opaque;
     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);
 
-    acb->hd_aiocb = NULL;
-
-    if (ret < 0) {
-        goto done;
-    }
-
+restart:
     acb->nb_sectors -= acb->n_sectors;
 
     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)) {
         /* Block not allocated, return zeros, no need to wait. */
         memset(acb->buf, 0, n_sectors * SECTOR_SIZE);
-        ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-        if (ret < 0) {
-            goto done;
-        }
+        ret = 0;
     } else {
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (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_len = n_sectors * SECTOR_SIZE;
         qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_readv(bs->file, offset, &acb->hd_qiov,
-                                       n_sectors, vdi_aio_read_cb, acb);
+        ret = bdrv_co_readv(bs->file, offset, n_sectors, &acb->hd_qiov);
+    }
+    if (ret >= 0) {
+        goto restart;
     }
-    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);
+    return ret;
 }
 
-static BlockDriverAIOCB *vdi_aio_readv(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
+static int vdi_co_readv(BlockDriverState *bs,
+        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
     VdiAIOCB *acb;
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
-    ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-    if (ret < 0) {
-        if (acb->qiov->niov > 1) {
-            qemu_vfree(acb->orig_buf);
-        }
-        qemu_aio_release(acb);
-        return NULL;
-    }
-
-    return &acb->common;
+    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
+    ret = vdi_aio_read_cb(acb, 0);
+    return ret;
 }
 
-static void vdi_aio_write_cb(void *opaque, int ret)
+static int vdi_aio_write_cb(void *opaque, int ret)
 {
     VdiAIOCB *acb = opaque;
     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 n_sectors;
 
-    acb->hd_aiocb = NULL;
-
-    if (ret < 0) {
-        goto done;
-    }
-
+restart:
     acb->nb_sectors -= acb->n_sectors;
     acb->sector_num += acb->n_sectors;
     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) {
         logout("finished data write\n");
         acb->n_sectors = 0;
+        ret = 0;
         if (acb->header_modified) {
             VdiHeader *header = acb->block_buffer;
             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_len = SECTOR_SIZE;
             qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            acb->hd_aiocb = bdrv_aio_writev(bs->file, 0, &acb->hd_qiov, 1,
-                                            vdi_aio_write_cb, acb);
-            return;
-        } else if (VDI_IS_ALLOCATED(acb->bmap_first)) {
+            ret = bdrv_co_writev(bs->file, 0, 1, &acb->hd_qiov);
+        }
+        if (ret >= 0 && VDI_IS_ALLOCATED(acb->bmap_first)) {
             /* One or more new blocks were allocated. */
             uint64_t offset;
             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);
             logout("will write %u block map sectors starting from entry %u\n",
                    n_sectors, bmap_first);
-            acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov,
-                                            n_sectors, vdi_aio_write_cb, acb);
-            return;
+            ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
         }
-        ret = 0;
         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_len = s->block_size;
         qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_writev(bs->file, offset,
-                                        &acb->hd_qiov, s->block_sectors,
-                                        vdi_aio_write_cb, acb);
+        ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &acb->hd_qiov);
     } else {
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (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_len = n_sectors * SECTOR_SIZE;
         qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_writev(bs->file, offset, &acb->hd_qiov,
-                                        n_sectors, vdi_aio_write_cb, acb);
+        ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
+    }
+    if (ret >= 0) {
+        goto restart;
     }
-
-    return;
 
 done:
     if (acb->qiov->niov > 1) {
         qemu_vfree(acb->orig_buf);
     }
-    acb->common.cb(acb->common.opaque, ret);
     qemu_aio_release(acb);
+    return ret;
 }
 
-static BlockDriverAIOCB *vdi_aio_writev(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
+static int vdi_co_writev(BlockDriverState *bs,
+        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
     VdiAIOCB *acb;
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
-    ret = vdi_schedule_bh(vdi_aio_rw_bh, acb);
-    if (ret < 0) {
-        if (acb->qiov->niov > 1) {
-            qemu_vfree(acb->orig_buf);
-        }
-        qemu_aio_release(acb);
-        return NULL;
-    }
-
-    return &acb->common;
+    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 1);
+    ret = vdi_aio_write_cb(acb, 0);
+    return ret;
 }
 
 static int vdi_create(const char *filename, QEMUOptionParameter *options)
@@ -973,9 +889,9 @@ static BlockDriver bdrv_vdi = {
     .bdrv_co_is_allocated = vdi_co_is_allocated,
     .bdrv_make_empty = vdi_make_empty,
 
-    .bdrv_aio_readv = vdi_aio_readv,
+    .bdrv_co_readv = vdi_co_readv,
 #if defined(CONFIG_VDI_WRITE)
-    .bdrv_aio_writev = vdi_aio_writev,
+    .bdrv_co_writev = vdi_co_writev,
 #endif
 
     .bdrv_get_info = vdi_get_info,
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 2/7] vdi: move end-of-I/O handling at the end

[Paolo Bonzini]

The next step is to take code that only triggers after the first operation,
and move it at the end of vdi_aio_read_cb and vdi_aio_write_cb.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |  123 +++++++++++++++++++++++++++--------------------------------
 1 files changed, 56 insertions(+), 67 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 35edc90..4b780db 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -533,20 +533,7 @@ static int vdi_aio_read_cb(void *opaque, int ret)
     uint32_t sector_in_block;
     uint32_t n_sectors;
 
-    logout("%u sectors read\n", acb->n_sectors);
-
 restart:
-    acb->nb_sectors -= acb->n_sectors;
-
-    if (acb->nb_sectors == 0) {
-        /* request completed */
-        ret = 0;
-        goto done;
-    }
-
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
-
     block_index = acb->sector_num / s->block_sectors;
     sector_in_block = acb->sector_num % s->block_sectors;
     n_sectors = s->block_sectors - sector_in_block;
@@ -573,11 +560,16 @@ restart:
         qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
         ret = bdrv_co_readv(bs->file, offset, n_sectors, &acb->hd_qiov);
     }
-    if (ret >= 0) {
+    logout("%u sectors read\n", acb->n_sectors);
+
+    acb->nb_sectors -= acb->n_sectors;
+    acb->sector_num += acb->n_sectors;
+    acb->buf += acb->n_sectors * SECTOR_SIZE;
+
+    if (ret >= 0 && acb->nb_sectors > 0) {
         goto restart;
     }
 
-done:
     if (acb->qiov->niov > 1) {
         qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
         qemu_vfree(acb->orig_buf);
@@ -609,56 +601,6 @@ static int vdi_aio_write_cb(void *opaque, int ret)
     uint32_t n_sectors;
 
 restart:
-    acb->nb_sectors -= acb->n_sectors;
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
-
-    if (acb->nb_sectors == 0) {
-        logout("finished data write\n");
-        acb->n_sectors = 0;
-        ret = 0;
-        if (acb->header_modified) {
-            VdiHeader *header = acb->block_buffer;
-            logout("now writing modified header\n");
-            assert(VDI_IS_ALLOCATED(acb->bmap_first));
-            *header = s->header;
-            vdi_header_to_le(header);
-            acb->header_modified = 0;
-            acb->hd_iov.iov_base = acb->block_buffer;
-            acb->hd_iov.iov_len = SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            ret = bdrv_co_writev(bs->file, 0, 1, &acb->hd_qiov);
-        }
-        if (ret >= 0 && VDI_IS_ALLOCATED(acb->bmap_first)) {
-            /* One or more new blocks were allocated. */
-            uint64_t offset;
-            uint32_t bmap_first;
-            uint32_t bmap_last;
-            g_free(acb->block_buffer);
-            acb->block_buffer = NULL;
-            bmap_first = acb->bmap_first;
-            bmap_last = acb->bmap_last;
-            logout("now writing modified block map entry %u...%u\n",
-                   bmap_first, bmap_last);
-            /* Write modified sectors from block map. */
-            bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
-            bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
-            n_sectors = bmap_last - bmap_first + 1;
-            offset = s->bmap_sector + bmap_first;
-            acb->bmap_first = VDI_UNALLOCATED;
-            acb->hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
-                                            bmap_first * SECTOR_SIZE);
-            acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            logout("will write %u block map sectors starting from entry %u\n",
-                   n_sectors, bmap_first);
-            ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
-        }
-        goto done;
-    }
-
-    logout("%u sectors written\n", acb->n_sectors);
-
     block_index = acb->sector_num / s->block_sectors;
     sector_in_block = acb->sector_num % s->block_sectors;
     n_sectors = s->block_sectors - sector_in_block;
@@ -709,11 +651,58 @@ restart:
         qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
         ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
     }
-    if (ret >= 0) {
+
+    acb->nb_sectors -= acb->n_sectors;
+    acb->sector_num += acb->n_sectors;
+    acb->buf += acb->n_sectors * SECTOR_SIZE;
+
+    logout("%u sectors written\n", acb->n_sectors);
+    if (ret >= 0 && acb->nb_sectors > 0) {
         goto restart;
     }
 
-done:
+    logout("finished data write\n");
+    if (ret >= 0) {
+        ret = 0;
+        if (acb->header_modified) {
+            VdiHeader *header = acb->block_buffer;
+            logout("now writing modified header\n");
+            assert(VDI_IS_ALLOCATED(acb->bmap_first));
+            *header = s->header;
+            vdi_header_to_le(header);
+            acb->header_modified = 0;
+            acb->hd_iov.iov_base = acb->block_buffer;
+            acb->hd_iov.iov_len = SECTOR_SIZE;
+            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
+            ret = bdrv_co_writev(bs->file, 0, 1, &acb->hd_qiov);
+        }
+        if (ret >= 0 && VDI_IS_ALLOCATED(acb->bmap_first)) {
+            /* One or more new blocks were allocated. */
+            uint64_t offset;
+            uint32_t bmap_first;
+            uint32_t bmap_last;
+            g_free(acb->block_buffer);
+            acb->block_buffer = NULL;
+            bmap_first = acb->bmap_first;
+            bmap_last = acb->bmap_last;
+            logout("now writing modified block map entry %u...%u\n",
+                   bmap_first, bmap_last);
+            /* Write modified sectors from block map. */
+            bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
+            bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
+            n_sectors = bmap_last - bmap_first + 1;
+            offset = s->bmap_sector + bmap_first;
+            acb->bmap_first = VDI_UNALLOCATED;
+            acb->hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
+                                            bmap_first * SECTOR_SIZE);
+            acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
+            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
+            logout("will write %u block map sectors starting from entry %u\n",
+                   n_sectors, bmap_first);
+            ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
+        }
+    }
+
     if (acb->qiov->niov > 1) {
         qemu_vfree(acb->orig_buf);
     }
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 3/7] vdi: merge aio_read_cb and aio_write_cb into callers

[Paolo Bonzini]

Now inline the former AIO callbacks into vdi_co_readv and vdi_co_writev.
While many cleanups are possible, the code now really looks synchronous.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |   40 ++++++++++++----------------------------
 1 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 4b780db..9e5b169 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -523,15 +523,19 @@ static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
     return acb;
 }
 
-static int vdi_aio_read_cb(void *opaque, int ret)
+static int vdi_co_readv(BlockDriverState *bs,
+        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
-    VdiAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
+    VdiAIOCB *acb;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    int ret;
+
+    logout("\n");
+    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
 
 restart:
     block_index = acb->sector_num / s->block_sectors;
@@ -578,27 +582,19 @@ restart:
     return ret;
 }
 
-static int vdi_co_readv(BlockDriverState *bs,
+static int vdi_co_writev(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
     VdiAIOCB *acb;
-    int ret;
-
-    logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
-    ret = vdi_aio_read_cb(acb, 0);
-    return ret;
-}
-
-static int vdi_aio_write_cb(void *opaque, int ret)
-{
-    VdiAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    int ret;
+
+    logout("\n");
+    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 1);
 
 restart:
     block_index = acb->sector_num / s->block_sectors;
@@ -710,18 +706,6 @@ restart:
     return ret;
 }
 
-static int vdi_co_writev(BlockDriverState *bs,
-        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
-{
-    VdiAIOCB *acb;
-    int ret;
-
-    logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 1);
-    ret = vdi_aio_write_cb(acb, 0);
-    return ret;
-}
-
 static int vdi_create(const char *filename, QEMUOptionParameter *options)
 {
     int fd;
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 4/7] vdi: move aiocb fields to locals

[Paolo Bonzini]

Most of the AIOCB really holds local variables that need to persist
across callback invocation.  It can go away now.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |  163 +++++++++++++++++++++++-----------------------------------
 1 files changed, 65 insertions(+), 98 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 9e5b169..a3b0eb0 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -145,24 +145,8 @@ void uuid_unparse(const uuid_t uu, char *out)
 
 typedef struct {
     BlockDriverAIOCB common;
-    int64_t sector_num;
-    QEMUIOVector *qiov;
     uint8_t *buf;
-    /* Total number of sectors. */
-    int nb_sectors;
-    /* Number of sectors for current AIO. */
-    int n_sectors;
-    /* New allocated block map entry. */
-    uint32_t bmap_first;
-    uint32_t bmap_last;
-    /* Buffer for new allocated block. */
-    void *block_buffer;
     void *orig_buf;
-    bool is_write;
-    int header_modified;
-    struct iovec hd_iov;
-    QEMUIOVector hd_qiov;
-    QEMUBH *bh;
 } VdiAIOCB;
 
 typedef struct {
@@ -492,34 +476,20 @@ static AIOPool vdi_aio_pool = {
     .aiocb_size = sizeof(VdiAIOCB),
 };
 
-static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, int64_t sector_num,
-        QEMUIOVector *qiov, int nb_sectors, int is_write)
+static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov)
 {
     VdiAIOCB *acb;
 
-    logout("%p, %" PRId64 ", %p, %d, %p, %p, %d\n",
-           bs, sector_num, qiov, nb_sectors, is_write);
+    logout("%p, %p\n", bs, qiov);
 
     acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);
-    acb->sector_num = sector_num;
-    acb->qiov = qiov;
-    acb->is_write = is_write;
 
     if (qiov->niov > 1) {
         acb->buf = qemu_blockalign(bs, qiov->size);
         acb->orig_buf = acb->buf;
-        if (is_write) {
-            qemu_iovec_to_buffer(qiov, acb->buf);
-        }
     } else {
         acb->buf = (uint8_t *)qiov->iov->iov_base;
     }
-    acb->nb_sectors = nb_sectors;
-    acb->n_sectors = 0;
-    acb->bmap_first = VDI_UNALLOCATED;
-    acb->bmap_last = VDI_UNALLOCATED;
-    acb->block_buffer = NULL;
-    acb->header_modified = 0;
     return acb;
 }
 
@@ -532,24 +502,25 @@ static int vdi_co_readv(BlockDriverState *bs,
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    struct iovec hd_iov;
+    QEMUIOVector hd_qiov;
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 0);
+    acb = vdi_aio_setup(bs, qiov);
 
 restart:
-    block_index = acb->sector_num / s->block_sectors;
-    sector_in_block = acb->sector_num % s->block_sectors;
+    block_index = sector_num / s->block_sectors;
+    sector_in_block = sector_num % s->block_sectors;
     n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > acb->nb_sectors) {
-        n_sectors = acb->nb_sectors;
+    if (n_sectors > nb_sectors) {
+        n_sectors = nb_sectors;
     }
 
     logout("will read %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, acb->sector_num);
+           n_sectors, sector_num);
 
     /* prepare next AIO request */
-    acb->n_sectors = n_sectors;
     bmap_entry = le32_to_cpu(s->bmap[block_index]);
     if (!VDI_IS_ALLOCATED(bmap_entry)) {
         /* Block not allocated, return zeros, no need to wait. */
@@ -559,23 +530,23 @@ restart:
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        acb->hd_iov.iov_base = (void *)acb->buf;
-        acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        ret = bdrv_co_readv(bs->file, offset, n_sectors, &acb->hd_qiov);
+        hd_iov.iov_base = (void *)acb->buf;
+        hd_iov.iov_len = n_sectors * SECTOR_SIZE;
+        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+        ret = bdrv_co_readv(bs->file, offset, n_sectors, &hd_qiov);
     }
-    logout("%u sectors read\n", acb->n_sectors);
+    logout("%u sectors read\n", n_sectors);
 
-    acb->nb_sectors -= acb->n_sectors;
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
+    nb_sectors -= n_sectors;
+    sector_num += n_sectors;
+    acb->buf += n_sectors * SECTOR_SIZE;
 
-    if (ret >= 0 && acb->nb_sectors > 0) {
+    if (ret >= 0 && nb_sectors > 0) {
         goto restart;
     }
 
-    if (acb->qiov->niov > 1) {
-        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
+    if (acb->orig_buf) {
+        qemu_iovec_from_buffer(qiov, acb->orig_buf, qiov->size);
         qemu_vfree(acb->orig_buf);
     }
     qemu_aio_release(acb);
@@ -591,96 +562,93 @@ static int vdi_co_writev(BlockDriverState *bs,
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
+    uint32_t bmap_first = VDI_UNALLOCATED;
+    uint32_t bmap_last = VDI_UNALLOCATED;
+    struct iovec hd_iov;
+    QEMUIOVector hd_qiov;
+    uint8_t *block = NULL;
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, sector_num, qiov, nb_sectors, 1);
+    acb = vdi_aio_setup(bs, qiov);
+    if (acb->orig_buf) {
+        qemu_iovec_to_buffer(qiov, acb->buf);
+    }
 
 restart:
-    block_index = acb->sector_num / s->block_sectors;
-    sector_in_block = acb->sector_num % s->block_sectors;
+    block_index = sector_num / s->block_sectors;
+    sector_in_block = sector_num % s->block_sectors;
     n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > acb->nb_sectors) {
-        n_sectors = acb->nb_sectors;
+    if (n_sectors > nb_sectors) {
+        n_sectors = nb_sectors;
     }
 
     logout("will write %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, acb->sector_num);
+           n_sectors, sector_num);
 
     /* prepare next AIO request */
-    acb->n_sectors = n_sectors;
     bmap_entry = le32_to_cpu(s->bmap[block_index]);
     if (!VDI_IS_ALLOCATED(bmap_entry)) {
         /* Allocate new block and write to it. */
         uint64_t offset;
-        uint8_t *block;
         bmap_entry = s->header.blocks_allocated;
         s->bmap[block_index] = cpu_to_le32(bmap_entry);
         s->header.blocks_allocated++;
         offset = s->header.offset_data / SECTOR_SIZE +
                  (uint64_t)bmap_entry * s->block_sectors;
-        block = acb->block_buffer;
         if (block == NULL) {
             block = g_malloc(s->block_size);
-            acb->block_buffer = block;
-            acb->bmap_first = block_index;
-            assert(!acb->header_modified);
-            acb->header_modified = 1;
+            bmap_first = block_index;
         }
-        acb->bmap_last = block_index;
+        bmap_last = block_index;
         /* Copy data to be written to new block and zero unused parts. */
         memset(block, 0, sector_in_block * SECTOR_SIZE);
         memcpy(block + sector_in_block * SECTOR_SIZE,
                acb->buf, n_sectors * SECTOR_SIZE);
         memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
                (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
-        acb->hd_iov.iov_base = (void *)block;
-        acb->hd_iov.iov_len = s->block_size;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &acb->hd_qiov);
+        hd_iov.iov_base = (void *)block;
+        hd_iov.iov_len = s->block_size;
+        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+        ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &hd_qiov);
     } else {
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        acb->hd_iov.iov_base = (void *)acb->buf;
-        acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
+        hd_iov.iov_base = (void *)acb->buf;
+        hd_iov.iov_len = n_sectors * SECTOR_SIZE;
+        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+        ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
     }
 
-    acb->nb_sectors -= acb->n_sectors;
-    acb->sector_num += acb->n_sectors;
-    acb->buf += acb->n_sectors * SECTOR_SIZE;
+    nb_sectors -= n_sectors;
+    sector_num += n_sectors;
+    acb->buf += n_sectors * SECTOR_SIZE;
 
-    logout("%u sectors written\n", acb->n_sectors);
-    if (ret >= 0 && acb->nb_sectors > 0) {
+    logout("%u sectors written\n", n_sectors);
+    if (ret >= 0 && nb_sectors > 0) {
         goto restart;
     }
 
     logout("finished data write\n");
     if (ret >= 0) {
         ret = 0;
-        if (acb->header_modified) {
-            VdiHeader *header = acb->block_buffer;
+        if (block) {
+            VdiHeader *header = (VdiHeader *) block;
             logout("now writing modified header\n");
-            assert(VDI_IS_ALLOCATED(acb->bmap_first));
+            assert(VDI_IS_ALLOCATED(bmap_first));
             *header = s->header;
             vdi_header_to_le(header);
-            acb->header_modified = 0;
-            acb->hd_iov.iov_base = acb->block_buffer;
-            acb->hd_iov.iov_len = SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-            ret = bdrv_co_writev(bs->file, 0, 1, &acb->hd_qiov);
+            hd_iov.iov_base = block;
+            hd_iov.iov_len = SECTOR_SIZE;
+            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+            ret = bdrv_co_writev(bs->file, 0, 1, &hd_qiov);
         }
-        if (ret >= 0 && VDI_IS_ALLOCATED(acb->bmap_first)) {
+        g_free(block);
+        block = NULL;
+        if (ret >= 0 && VDI_IS_ALLOCATED(bmap_first)) {
             /* One or more new blocks were allocated. */
             uint64_t offset;
-            uint32_t bmap_first;
-            uint32_t bmap_last;
-            g_free(acb->block_buffer);
-            acb->block_buffer = NULL;
-            bmap_first = acb->bmap_first;
-            bmap_last = acb->bmap_last;
             logout("now writing modified block map entry %u...%u\n",
                    bmap_first, bmap_last);
             /* Write modified sectors from block map. */
@@ -688,18 +656,17 @@ restart:
             bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
             n_sectors = bmap_last - bmap_first + 1;
             offset = s->bmap_sector + bmap_first;
-            acb->bmap_first = VDI_UNALLOCATED;
-            acb->hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
+            hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
                                             bmap_first * SECTOR_SIZE);
-            acb->hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-            qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
+            hd_iov.iov_len = n_sectors * SECTOR_SIZE;
+            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
             logout("will write %u block map sectors starting from entry %u\n",
                    n_sectors, bmap_first);
-            ret = bdrv_co_writev(bs->file, offset, n_sectors, &acb->hd_qiov);
+            ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
         }
     }
 
-    if (acb->qiov->niov > 1) {
+    if (acb->orig_buf) {
         qemu_vfree(acb->orig_buf);
     }
     qemu_aio_release(acb);
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 5/7] vdi: leave bounce buffering to block layer

[Paolo Bonzini]

vdi.c really works as if it implemented bdrv_read and bdrv_write.  However,
because only vector I/O is supported by the asynchronous callbacks, it
went through extra pain to bounce-buffer the I/O.  This can be handled
by the block layer now that the format is coroutine-based.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |   67 ++++++++++------------------------------------------------
 1 files changed, 12 insertions(+), 55 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index a3b0eb0..ccbdf67 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -144,12 +144,6 @@ void uuid_unparse(const uuid_t uu, char *out)
 #endif
 
 typedef struct {
-    BlockDriverAIOCB common;
-    uint8_t *buf;
-    void *orig_buf;
-} VdiAIOCB;
-
-typedef struct {
     char text[0x40];
     uint32_t signature;
     uint32_t version;
@@ -472,31 +466,9 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs,
     return VDI_IS_ALLOCATED(bmap_entry);
 }
 
-static AIOPool vdi_aio_pool = {
-    .aiocb_size = sizeof(VdiAIOCB),
-};
-
-static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov)
+static int vdi_co_read(BlockDriverState *bs,
+        int64_t sector_num, uint8_t *buf, int nb_sectors)
 {
-    VdiAIOCB *acb;
-
-    logout("%p, %p\n", bs, qiov);
-
-    acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);
-
-    if (qiov->niov > 1) {
-        acb->buf = qemu_blockalign(bs, qiov->size);
-        acb->orig_buf = acb->buf;
-    } else {
-        acb->buf = (uint8_t *)qiov->iov->iov_base;
-    }
-    return acb;
-}
-
-static int vdi_co_readv(BlockDriverState *bs,
-        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
-{
-    VdiAIOCB *acb;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
@@ -507,7 +479,6 @@ static int vdi_co_readv(BlockDriverState *bs,
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, qiov);
 
 restart:
     block_index = sector_num / s->block_sectors;
@@ -524,13 +495,13 @@ restart:
     bmap_entry = le32_to_cpu(s->bmap[block_index]);
     if (!VDI_IS_ALLOCATED(bmap_entry)) {
         /* Block not allocated, return zeros, no need to wait. */
-        memset(acb->buf, 0, n_sectors * SECTOR_SIZE);
+        memset(buf, 0, n_sectors * SECTOR_SIZE);
         ret = 0;
     } else {
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        hd_iov.iov_base = (void *)acb->buf;
+        hd_iov.iov_base = (void *)buf;
         hd_iov.iov_len = n_sectors * SECTOR_SIZE;
         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
         ret = bdrv_co_readv(bs->file, offset, n_sectors, &hd_qiov);
@@ -539,24 +510,18 @@ restart:
 
     nb_sectors -= n_sectors;
     sector_num += n_sectors;
-    acb->buf += n_sectors * SECTOR_SIZE;
+    buf += n_sectors * SECTOR_SIZE;
 
     if (ret >= 0 && nb_sectors > 0) {
         goto restart;
     }
 
-    if (acb->orig_buf) {
-        qemu_iovec_from_buffer(qiov, acb->orig_buf, qiov->size);
-        qemu_vfree(acb->orig_buf);
-    }
-    qemu_aio_release(acb);
     return ret;
 }
 
-static int vdi_co_writev(BlockDriverState *bs,
-        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+static int vdi_co_write(BlockDriverState *bs,
+        int64_t sector_num, const uint8_t *buf, int nb_sectors)
 {
-    VdiAIOCB *acb;
     BDRVVdiState *s = bs->opaque;
     uint32_t bmap_entry;
     uint32_t block_index;
@@ -570,10 +535,6 @@ static int vdi_co_writev(BlockDriverState *bs,
     int ret;
 
     logout("\n");
-    acb = vdi_aio_setup(bs, qiov);
-    if (acb->orig_buf) {
-        qemu_iovec_to_buffer(qiov, acb->buf);
-    }
 
 restart:
     block_index = sector_num / s->block_sectors;
@@ -604,7 +565,7 @@ restart:
         /* Copy data to be written to new block and zero unused parts. */
         memset(block, 0, sector_in_block * SECTOR_SIZE);
         memcpy(block + sector_in_block * SECTOR_SIZE,
-               acb->buf, n_sectors * SECTOR_SIZE);
+               buf, n_sectors * SECTOR_SIZE);
         memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
                (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
         hd_iov.iov_base = (void *)block;
@@ -615,7 +576,7 @@ restart:
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        hd_iov.iov_base = (void *)acb->buf;
+        hd_iov.iov_base = (void *)buf;
         hd_iov.iov_len = n_sectors * SECTOR_SIZE;
         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
         ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
@@ -623,7 +584,7 @@ restart:
 
     nb_sectors -= n_sectors;
     sector_num += n_sectors;
-    acb->buf += n_sectors * SECTOR_SIZE;
+    buf += n_sectors * SECTOR_SIZE;
 
     logout("%u sectors written\n", n_sectors);
     if (ret >= 0 && nb_sectors > 0) {
@@ -666,10 +627,6 @@ restart:
         }
     }
 
-    if (acb->orig_buf) {
-        qemu_vfree(acb->orig_buf);
-    }
-    qemu_aio_release(acb);
     return ret;
 }
 
@@ -829,9 +786,9 @@ static BlockDriver bdrv_vdi = {
     .bdrv_co_is_allocated = vdi_co_is_allocated,
     .bdrv_make_empty = vdi_make_empty,
 
-    .bdrv_co_readv = vdi_co_readv,
+    .bdrv_read = vdi_co_read,
 #if defined(CONFIG_VDI_WRITE)
-    .bdrv_co_writev = vdi_co_writev,
+    .bdrv_write = vdi_co_write,
 #endif
 
     .bdrv_get_info = vdi_get_info,
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 6/7] vdi: do not create useless iovecs

[Paolo Bonzini]

Reads and writes to the underlying file can also occur with the simple
non-vectored I/O interfaces.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |   79 ++++++++++++++++++++++++----------------------------------
 1 files changed, 33 insertions(+), 46 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index ccbdf67..2202819 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -474,8 +474,6 @@ static int vdi_co_read(BlockDriverState *bs,
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
-    struct iovec hd_iov;
-    QEMUIOVector hd_qiov;
     int ret;
 
     logout("\n");
@@ -501,10 +499,7 @@ restart:
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        hd_iov.iov_base = (void *)buf;
-        hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
-        ret = bdrv_co_readv(bs->file, offset, n_sectors, &hd_qiov);
+        ret = bdrv_read(bs->file, offset, buf, n_sectors);
     }
     logout("%u sectors read\n", n_sectors);
 
@@ -529,8 +524,6 @@ static int vdi_co_write(BlockDriverState *bs,
     uint32_t n_sectors;
     uint32_t bmap_first = VDI_UNALLOCATED;
     uint32_t bmap_last = VDI_UNALLOCATED;
-    struct iovec hd_iov;
-    QEMUIOVector hd_qiov;
     uint8_t *block = NULL;
     int ret;
 
@@ -568,18 +561,12 @@ restart:
                buf, n_sectors * SECTOR_SIZE);
         memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
                (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
-        hd_iov.iov_base = (void *)block;
-        hd_iov.iov_len = s->block_size;
-        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
-        ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &hd_qiov);
+        ret = bdrv_write(bs->file, offset, block, s->block_sectors);
     } else {
         uint64_t offset = s->header.offset_data / SECTOR_SIZE +
                           (uint64_t)bmap_entry * s->block_sectors +
                           sector_in_block;
-        hd_iov.iov_base = (void *)buf;
-        hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
-        ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
+        ret = bdrv_write(bs->file, offset, buf, n_sectors);
     }
 
     nb_sectors -= n_sectors;
@@ -592,39 +579,39 @@ restart:
     }
 
     logout("finished data write\n");
-    if (ret >= 0) {
-        ret = 0;
-        if (block) {
-            VdiHeader *header = (VdiHeader *) block;
-            logout("now writing modified header\n");
-            assert(VDI_IS_ALLOCATED(bmap_first));
-            *header = s->header;
-            vdi_header_to_le(header);
-            hd_iov.iov_base = block;
-            hd_iov.iov_len = SECTOR_SIZE;
-            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
-            ret = bdrv_co_writev(bs->file, 0, 1, &hd_qiov);
-        }
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (block) {
+        /* One or more new blocks were allocated. */
+        VdiHeader *header = (VdiHeader *) block;
+        uint8_t *base;
+        uint64_t offset;
+
+        logout("now writing modified header\n");
+        assert(VDI_IS_ALLOCATED(bmap_first));
+        *header = s->header;
+        vdi_header_to_le(header);
+        ret = bdrv_write(bs->file, 0, block, 1);
         g_free(block);
         block = NULL;
-        if (ret >= 0 && VDI_IS_ALLOCATED(bmap_first)) {
-            /* One or more new blocks were allocated. */
-            uint64_t offset;
-            logout("now writing modified block map entry %u...%u\n",
-                   bmap_first, bmap_last);
-            /* Write modified sectors from block map. */
-            bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
-            bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
-            n_sectors = bmap_last - bmap_first + 1;
-            offset = s->bmap_sector + bmap_first;
-            hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +
-                                            bmap_first * SECTOR_SIZE);
-            hd_iov.iov_len = n_sectors * SECTOR_SIZE;
-            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
-            logout("will write %u block map sectors starting from entry %u\n",
-                   n_sectors, bmap_first);
-            ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
+
+        if (ret < 0) {
+            return ret;
         }
+
+        logout("now writing modified block map entry %u...%u\n",
+               bmap_first, bmap_last);
+        /* Write modified sectors from block map. */
+        bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
+        bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
+        n_sectors = bmap_last - bmap_first + 1;
+        offset = s->bmap_sector + bmap_first;
+        base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
+        logout("will write %u block map sectors starting from entry %u\n",
+               n_sectors, bmap_first);
+        ret = bdrv_write(bs->file, offset, base, n_sectors);
     }
 
     return ret;
-- 
1.7.7.6

[Qemu-devel] [PATCH v2 7/7] vdi: change goto to loop

[Paolo Bonzini]

Finally reindent all code and change goto statements to a loop.

Acked-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vdi.c |  141 ++++++++++++++++++++++++++++------------------------------
 1 files changed, 68 insertions(+), 73 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 2202819..34aa232 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -474,41 +474,38 @@ static int vdi_co_read(BlockDriverState *bs,
     uint32_t block_index;
     uint32_t sector_in_block;
     uint32_t n_sectors;
-    int ret;
+    int ret = 0;
 
     logout("\n");
 
-restart:
-    block_index = sector_num / s->block_sectors;
-    sector_in_block = sector_num % s->block_sectors;
-    n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > nb_sectors) {
-        n_sectors = nb_sectors;
-    }
-
-    logout("will read %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, sector_num);
+    while (ret >= 0 && nb_sectors > 0) {
+        block_index = sector_num / s->block_sectors;
+        sector_in_block = sector_num % s->block_sectors;
+        n_sectors = s->block_sectors - sector_in_block;
+        if (n_sectors > nb_sectors) {
+            n_sectors = nb_sectors;
+        }
 
-    /* prepare next AIO request */
-    bmap_entry = le32_to_cpu(s->bmap[block_index]);
-    if (!VDI_IS_ALLOCATED(bmap_entry)) {
-        /* Block not allocated, return zeros, no need to wait. */
-        memset(buf, 0, n_sectors * SECTOR_SIZE);
-        ret = 0;
-    } else {
-        uint64_t offset = s->header.offset_data / SECTOR_SIZE +
-                          (uint64_t)bmap_entry * s->block_sectors +
-                          sector_in_block;
-        ret = bdrv_read(bs->file, offset, buf, n_sectors);
-    }
-    logout("%u sectors read\n", n_sectors);
+        logout("will read %u sectors starting at sector %" PRIu64 "\n",
+               n_sectors, sector_num);
 
-    nb_sectors -= n_sectors;
-    sector_num += n_sectors;
-    buf += n_sectors * SECTOR_SIZE;
+        /* prepare next AIO request */
+        bmap_entry = le32_to_cpu(s->bmap[block_index]);
+        if (!VDI_IS_ALLOCATED(bmap_entry)) {
+            /* Block not allocated, return zeros, no need to wait. */
+            memset(buf, 0, n_sectors * SECTOR_SIZE);
+            ret = 0;
+        } else {
+            uint64_t offset = s->header.offset_data / SECTOR_SIZE +
+                              (uint64_t)bmap_entry * s->block_sectors +
+                              sector_in_block;
+            ret = bdrv_read(bs->file, offset, buf, n_sectors);
+        }
+        logout("%u sectors read\n", n_sectors);
 
-    if (ret >= 0 && nb_sectors > 0) {
-        goto restart;
+        nb_sectors -= n_sectors;
+        sector_num += n_sectors;
+        buf += n_sectors * SECTOR_SIZE;
     }
 
     return ret;
@@ -525,57 +522,55 @@ static int vdi_co_write(BlockDriverState *bs,
     uint32_t bmap_first = VDI_UNALLOCATED;
     uint32_t bmap_last = VDI_UNALLOCATED;
     uint8_t *block = NULL;
-    int ret;
+    int ret = 0;
 
     logout("\n");
 
-restart:
-    block_index = sector_num / s->block_sectors;
-    sector_in_block = sector_num % s->block_sectors;
-    n_sectors = s->block_sectors - sector_in_block;
-    if (n_sectors > nb_sectors) {
-        n_sectors = nb_sectors;
-    }
-
-    logout("will write %u sectors starting at sector %" PRIu64 "\n",
-           n_sectors, sector_num);
+    while (ret >= 0 && nb_sectors > 0) {
+        block_index = sector_num / s->block_sectors;
+        sector_in_block = sector_num % s->block_sectors;
+        n_sectors = s->block_sectors - sector_in_block;
+        if (n_sectors > nb_sectors) {
+            n_sectors = nb_sectors;
+        }
 
-    /* prepare next AIO request */
-    bmap_entry = le32_to_cpu(s->bmap[block_index]);
-    if (!VDI_IS_ALLOCATED(bmap_entry)) {
-        /* Allocate new block and write to it. */
-        uint64_t offset;
-        bmap_entry = s->header.blocks_allocated;
-        s->bmap[block_index] = cpu_to_le32(bmap_entry);
-        s->header.blocks_allocated++;
-        offset = s->header.offset_data / SECTOR_SIZE +
-                 (uint64_t)bmap_entry * s->block_sectors;
-        if (block == NULL) {
-            block = g_malloc(s->block_size);
-            bmap_first = block_index;
+        logout("will write %u sectors starting at sector %" PRIu64 "\n",
+               n_sectors, sector_num);
+
+        /* prepare next AIO request */
+        bmap_entry = le32_to_cpu(s->bmap[block_index]);
+        if (!VDI_IS_ALLOCATED(bmap_entry)) {
+            /* Allocate new block and write to it. */
+            uint64_t offset;
+            bmap_entry = s->header.blocks_allocated;
+            s->bmap[block_index] = cpu_to_le32(bmap_entry);
+            s->header.blocks_allocated++;
+            offset = s->header.offset_data / SECTOR_SIZE +
+                     (uint64_t)bmap_entry * s->block_sectors;
+            if (block == NULL) {
+                block = g_malloc(s->block_size);
+                bmap_first = block_index;
+            }
+            bmap_last = block_index;
+            /* Copy data to be written to new block and zero unused parts. */
+            memset(block, 0, sector_in_block * SECTOR_SIZE);
+            memcpy(block + sector_in_block * SECTOR_SIZE,
+                   buf, n_sectors * SECTOR_SIZE);
+            memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
+                   (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
+            ret = bdrv_write(bs->file, offset, block, s->block_sectors);
+        } else {
+            uint64_t offset = s->header.offset_data / SECTOR_SIZE +
+                              (uint64_t)bmap_entry * s->block_sectors +
+                              sector_in_block;
+            ret = bdrv_write(bs->file, offset, buf, n_sectors);
         }
-        bmap_last = block_index;
-        /* Copy data to be written to new block and zero unused parts. */
-        memset(block, 0, sector_in_block * SECTOR_SIZE);
-        memcpy(block + sector_in_block * SECTOR_SIZE,
-               buf, n_sectors * SECTOR_SIZE);
-        memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,
-               (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);
-        ret = bdrv_write(bs->file, offset, block, s->block_sectors);
-    } else {
-        uint64_t offset = s->header.offset_data / SECTOR_SIZE +
-                          (uint64_t)bmap_entry * s->block_sectors +
-                          sector_in_block;
-        ret = bdrv_write(bs->file, offset, buf, n_sectors);
-    }
 
-    nb_sectors -= n_sectors;
-    sector_num += n_sectors;
-    buf += n_sectors * SECTOR_SIZE;
+        nb_sectors -= n_sectors;
+        sector_num += n_sectors;
+        buf += n_sectors * SECTOR_SIZE;
 
-    logout("%u sectors written\n", n_sectors);
-    if (ret >= 0 && nb_sectors > 0) {
-        goto restart;
+        logout("%u sectors written\n", n_sectors);
     }
 
     logout("finished data write\n");
-- 
1.7.7.6

Re: [Qemu-devel] [PATCH v2 0/7] vdi: convert to coroutines

[Kevin Wolf]

Am 19.03.2012 18:07, schrieb Paolo Bonzini:
> This squashes in the fix for GCC's uninitialized variables false positive.
> 
> Paolo Bonzini (7):
>   vdi: basic conversion to coroutines
>   vdi: move end-of-I/O handling at the end
>   vdi: merge aio_read_cb and aio_write_cb into callers
>   vdi: move aiocb fields to locals
>   vdi: leave bounce buffering to block layer
>   vdi: do not create useless iovecs
>   vdi: change goto to loop
> 
>  block/vdi.c |  421 +++++++++++++++--------------------------------------------
>  1 files changed, 108 insertions(+), 313 deletions(-)
> 

Thanks, updated the patches in the block branch.

Kevin