[Qemu-devel] [PATCH v2 12/17] vmdk: Implement .bdrv_co_preadv() interface

[Kevin Wolf <kwolf@redhat.com>]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vmdk.c | 98 ++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 53 insertions(+), 45 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index f1e01f9..6c447ad 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1381,8 +1381,8 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
 }
 
 static int vmdk_read_extent(VmdkExtent *extent, int64_t cluster_offset,
-                            int64_t offset_in_cluster, uint8_t *buf,
-                            int nb_sectors)
+                            int64_t offset_in_cluster, QEMUIOVector *qiov,
+                            int bytes)
 {
     int ret;
     int cluster_bytes, buf_bytes;
@@ -1394,14 +1394,13 @@ static int vmdk_read_extent(VmdkExtent *extent, int64_t cluster_offset,
 
 
     if (!extent->compressed) {
-        ret = bdrv_pread(extent->file->bs,
-                          cluster_offset + offset_in_cluster,
-                          buf, nb_sectors * 512);
-        if (ret == nb_sectors * 512) {
-            return 0;
-        } else {
-            return -EIO;
+        ret = bdrv_co_preadv(extent->file->bs,
+                             cluster_offset + offset_in_cluster, bytes,
+                             qiov, 0);
+        if (ret < 0) {
+            return ret;
         }
+        return 0;
     }
     cluster_bytes = extent->cluster_sectors * 512;
     /* Read two clusters in case GrainMarker + compressed data > one cluster */
@@ -1433,11 +1432,11 @@ static int vmdk_read_extent(VmdkExtent *extent, int64_t cluster_offset,
 
     }
     if (offset_in_cluster < 0 ||
-            offset_in_cluster + nb_sectors * 512 > buf_len) {
+            offset_in_cluster + bytes > buf_len) {
         ret = -EINVAL;
         goto out;
     }
-    memcpy(buf, uncomp_buf + offset_in_cluster, nb_sectors * 512);
+    qemu_iovec_from_buf(qiov, 0, uncomp_buf + offset_in_cluster, bytes);
     ret = 0;
 
  out:
@@ -1446,64 +1445,73 @@ static int vmdk_read_extent(VmdkExtent *extent, int64_t cluster_offset,
     return ret;
 }
 
-static int vmdk_read(BlockDriverState *bs, int64_t sector_num,
-                    uint8_t *buf, int nb_sectors)
+static int coroutine_fn
+vmdk_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+               QEMUIOVector *qiov, int flags)
 {
     BDRVVmdkState *s = bs->opaque;
     int ret;
-    uint64_t n, index_in_cluster;
+    uint64_t n_bytes, offset_in_cluster;
     VmdkExtent *extent = NULL;
+    QEMUIOVector local_qiov;
     uint64_t cluster_offset;
+    uint64_t bytes_done = 0;
 
-    while (nb_sectors > 0) {
-        extent = find_extent(s, sector_num, extent);
+    qemu_iovec_init(&local_qiov, qiov->niov);
+    qemu_co_mutex_lock(&s->lock);
+
+    while (bytes > 0) {
+        extent = find_extent(s, offset >> BDRV_SECTOR_BITS, extent);
         if (!extent) {
-            return -EIO;
+            ret = -EIO;
+            goto fail;
         }
         ret = get_cluster_offset(bs, extent, NULL,
-                                 sector_num << 9, false, &cluster_offset,
-                                 0, 0);
-        index_in_cluster = vmdk_find_index_in_cluster(extent, sector_num);
-        n = extent->cluster_sectors - index_in_cluster;
-        if (n > nb_sectors) {
-            n = nb_sectors;
-        }
+                                 offset, false, &cluster_offset, 0, 0);
+        offset_in_cluster = vmdk_find_offset_in_cluster(extent, offset);
+
+        n_bytes = MIN(bytes, extent->cluster_sectors * BDRV_SECTOR_SIZE
+                             - offset_in_cluster);
+
         if (ret != VMDK_OK) {
             /* if not allocated, try to read from parent image, if exist */
             if (bs->backing && ret != VMDK_ZEROED) {
                 if (!vmdk_is_cid_valid(bs)) {
-                    return -EINVAL;
+                    ret = -EINVAL;
+                    goto fail;
                 }
-                ret = bdrv_read(bs->backing->bs, sector_num, buf, n);
+
+                qemu_iovec_reset(&local_qiov);
+                qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
+
+                ret = bdrv_co_preadv(bs->backing->bs, offset, n_bytes,
+                                     &local_qiov, 0);
                 if (ret < 0) {
-                    return ret;
+                    goto fail;
                 }
             } else {
-                memset(buf, 0, 512 * n);
+                qemu_iovec_memset(qiov, bytes_done, 0, n_bytes);
             }
         } else {
-            ret = vmdk_read_extent(extent,
-                            cluster_offset, index_in_cluster * 512,
-                            buf, n);
+            qemu_iovec_reset(&local_qiov);
+            qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
+
+            ret = vmdk_read_extent(extent, cluster_offset, offset_in_cluster,
+                                   &local_qiov, n_bytes);
             if (ret) {
-                return ret;
+                goto fail;
             }
         }
-        nb_sectors -= n;
-        sector_num += n;
-        buf += n * 512;
+        bytes -= n_bytes;
+        offset += n_bytes;
+        bytes_done += n_bytes;
     }
-    return 0;
-}
 
-static coroutine_fn int vmdk_co_read(BlockDriverState *bs, int64_t sector_num,
-                                     uint8_t *buf, int nb_sectors)
-{
-    int ret;
-    BDRVVmdkState *s = bs->opaque;
-    qemu_co_mutex_lock(&s->lock);
-    ret = vmdk_read(bs, sector_num, buf, nb_sectors);
+    ret = 0;
+fail:
     qemu_co_mutex_unlock(&s->lock);
+    qemu_iovec_destroy(&local_qiov);
+
     return ret;
 }
 
@@ -2332,7 +2340,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_open                    = vmdk_open,
     .bdrv_check                   = vmdk_check,
     .bdrv_reopen_prepare          = vmdk_reopen_prepare,
-    .bdrv_read                    = vmdk_co_read,
+    .bdrv_co_preadv               = vmdk_co_preadv,
     .bdrv_write                   = vmdk_co_write,
     .bdrv_write_compressed        = vmdk_write_compressed,
     .bdrv_co_write_zeroes         = vmdk_co_write_zeroes,
-- 
1.8.3.1