[Qemu-devel] [PATCH v2 12/17] block: Convert bdrv_write() to BdrvChild

[Kevin Wolf <kwolf@redhat.com>]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---

This patch contains non-trivial fixes, so I think it's worth sending out a v2
for it even though I already applied the series. I added a coroutine entry
wrapper qcow(2)_write that can be used from .bdrv_write_compressed. These
wrappers will soon disappear again when .bdrv_write_compressed is changed into
.bdrv_co_pwritev_compressed (Pavel Butsykin's backup compression series).

 block/io.c             |  5 +++--
 block/qcow.c           | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 block/qcow2-cluster.c  |  2 +-
 block/qcow2-refcount.c |  2 +-
 block/qcow2.c          | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
 block/vdi.c            |  4 ++--
 block/vvfat.c          |  5 ++---
 include/block/block.h  |  2 +-
 8 files changed, 100 insertions(+), 12 deletions(-)

diff --git a/block/io.c b/block/io.c
index 6dfc0eb..2e04a80 100644
--- a/block/io.c
+++ b/block/io.c
@@ -642,10 +642,11 @@ int bdrv_read(BdrvChild *child, int64_t sector_num,
   -EINVAL      Invalid sector number or nb_sectors
   -EACCES      Trying to write a read-only device
 */
-int bdrv_write(BlockDriverState *bs, int64_t sector_num,
+int bdrv_write(BdrvChild *child, int64_t sector_num,
                const uint8_t *buf, int nb_sectors)
 {
-    return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
+    return bdrv_rw_co(child->bs, sector_num, (uint8_t *)buf, nb_sectors,
+                      true, 0);
 }
 
 int bdrv_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
diff --git a/block/qcow.c b/block/qcow.c
index 0db43f8..674595e 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -913,6 +913,49 @@ static int qcow_make_empty(BlockDriverState *bs)
     return 0;
 }
 
+typedef struct QcowWriteCo {
+    BlockDriverState *bs;
+    int64_t sector_num;
+    const uint8_t *buf;
+    int nb_sectors;
+    int ret;
+} QcowWriteCo;
+
+static void qcow_write_co_entry(void *opaque)
+{
+    QcowWriteCo *co = opaque;
+    QEMUIOVector qiov;
+
+    struct iovec iov = (struct iovec) {
+        .iov_base   = (uint8_t*) co->buf,
+        .iov_len    = co->nb_sectors * BDRV_SECTOR_SIZE,
+    };
+    qemu_iovec_init_external(&qiov, &iov, 1);
+
+    co->ret = qcow_co_writev(co->bs, co->sector_num, co->nb_sectors, &qiov);
+}
+
+/* Wrapper for non-coroutine contexts */
+static int qcow_write(BlockDriverState *bs, int64_t sector_num,
+                      const uint8_t *buf, int nb_sectors)
+{
+    Coroutine *co;
+    AioContext *aio_context = bdrv_get_aio_context(bs);
+    QcowWriteCo data = {
+        .bs         = bs,
+        .sector_num = sector_num,
+        .buf        = buf,
+        .nb_sectors = nb_sectors,
+        .ret        = -EINPROGRESS,
+    };
+    co = qemu_coroutine_create(qcow_write_co_entry);
+    qemu_coroutine_enter(co, &data);
+    while (data.ret == -EINPROGRESS) {
+        aio_poll(aio_context, true);
+    }
+    return data.ret;
+}
+
 /* XXX: put compressed sectors first, then all the cluster aligned
    tables to avoid losing bytes in alignment */
 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
@@ -969,7 +1012,7 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 
     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
         /* could not compress: write normal cluster */
-        ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
+        ret = qcow_write(bs, sector_num, buf, s->cluster_sectors);
         if (ret < 0) {
             goto fail;
         }
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index c1e9eee..a2490d7 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1784,7 +1784,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
                     goto fail;
                 }
 
-                ret = bdrv_write(bs->file->bs, l2_offset / BDRV_SECTOR_SIZE,
+                ret = bdrv_write(bs->file, l2_offset / BDRV_SECTOR_SIZE,
                                  (void *)l2_table, s->cluster_sectors);
                 if (ret < 0) {
                     goto fail;
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 3bef410..12e7e6b 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -2098,7 +2098,7 @@ write_refblocks:
         on_disk_refblock = (void *)((char *) *refcount_table +
                                     refblock_index * s->cluster_size);
 
-        ret = bdrv_write(bs->file->bs, refblock_offset / BDRV_SECTOR_SIZE,
+        ret = bdrv_write(bs->file, refblock_offset / BDRV_SECTOR_SIZE,
                          on_disk_refblock, s->cluster_sectors);
         if (ret < 0) {
             fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
diff --git a/block/qcow2.c b/block/qcow2.c
index 0178931..cd9c27b 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2533,6 +2533,51 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
     return 0;
 }
 
+typedef struct Qcow2WriteCo {
+    BlockDriverState *bs;
+    int64_t sector_num;
+    const uint8_t *buf;
+    int nb_sectors;
+    int ret;
+} Qcow2WriteCo;
+
+static void qcow2_write_co_entry(void *opaque)
+{
+    Qcow2WriteCo *co = opaque;
+    QEMUIOVector qiov;
+    uint64_t offset = co->sector_num * BDRV_SECTOR_SIZE;
+    uint64_t bytes = co->nb_sectors * BDRV_SECTOR_SIZE;
+
+    struct iovec iov = (struct iovec) {
+        .iov_base   = (uint8_t*) co->buf,
+        .iov_len    = bytes,
+    };
+    qemu_iovec_init_external(&qiov, &iov, 1);
+
+    co->ret = qcow2_co_pwritev(co->bs, offset, bytes, &qiov, 0);
+}
+
+/* Wrapper for non-coroutine contexts */
+static int qcow2_write(BlockDriverState *bs, int64_t sector_num,
+                       const uint8_t *buf, int nb_sectors)
+{
+    Coroutine *co;
+    AioContext *aio_context = bdrv_get_aio_context(bs);
+    Qcow2WriteCo data = {
+        .bs         = bs,
+        .sector_num = sector_num,
+        .buf        = buf,
+        .nb_sectors = nb_sectors,
+        .ret        = -EINPROGRESS,
+    };
+    co = qemu_coroutine_create(qcow2_write_co_entry);
+    qemu_coroutine_enter(co, &data);
+    while (data.ret == -EINPROGRESS) {
+        aio_poll(aio_context, true);
+    }
+    return data.ret;
+}
+
 /* XXX: put compressed sectors first, then all the cluster aligned
    tables to avoid losing bytes in alignment */
 static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
@@ -2596,7 +2641,7 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
 
     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
         /* could not compress: write normal cluster */
-        ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
+        ret = qcow2_write(bs, sector_num, buf, s->cluster_sectors);
         if (ret < 0) {
             goto fail;
         }
diff --git a/block/vdi.c b/block/vdi.c
index 46a3436..b2871ca 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -719,7 +719,7 @@ vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
         assert(VDI_IS_ALLOCATED(bmap_first));
         *header = s->header;
         vdi_header_to_le(header);
-        ret = bdrv_write(bs->file->bs, 0, block, 1);
+        ret = bdrv_write(bs->file, 0, block, 1);
         g_free(block);
         block = NULL;
 
@@ -737,7 +737,7 @@ vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
         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->bs, offset, base, n_sectors);
+        ret = bdrv_write(bs->file, offset, base, n_sectors);
     }
 
     return ret;
diff --git a/block/vvfat.c b/block/vvfat.c
index 5f980bb..c3f24c6 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1834,8 +1834,7 @@ static uint32_t get_cluster_count_for_direntry(BDRVVVFATState* s,
                         if (res) {
                             return -1;
                         }
-                        res = bdrv_write(s->qcow->bs, offset,
-                                         s->cluster_buffer, 1);
+                        res = bdrv_write(s->qcow, offset, s->cluster_buffer, 1);
                         if (res) {
                             return -2;
                         }
@@ -2889,7 +2888,7 @@ DLOG(checkpoint());
      * Use qcow backend. Commit later.
      */
 DLOG(fprintf(stderr, "Write to qcow backend: %d + %d\n", (int)sector_num, nb_sectors));
-    ret = bdrv_write(s->qcow->bs, sector_num, buf, nb_sectors);
+    ret = bdrv_write(s->qcow, sector_num, buf, nb_sectors);
     if (ret < 0) {
 	fprintf(stderr, "Error writing to qcow backend\n");
 	return ret;
diff --git a/include/block/block.h b/include/block/block.h
index b6744ab..ea17936 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -228,7 +228,7 @@ void bdrv_reopen_commit(BDRVReopenState *reopen_state);
 void bdrv_reopen_abort(BDRVReopenState *reopen_state);
 int bdrv_read(BdrvChild *child, int64_t sector_num,
               uint8_t *buf, int nb_sectors);
-int bdrv_write(BlockDriverState *bs, int64_t sector_num,
+int bdrv_write(BdrvChild *child, int64_t sector_num,
                const uint8_t *buf, int nb_sectors);
 int bdrv_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
                        int count, BdrvRequestFlags flags);
-- 
1.8.3.1