[Qemu-devel] [PULL 13/69] bochs: Implement .bdrv_co_preadv() interface

[Kevin Wolf <kwolf@redhat.com>]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
---
 block/bochs.c | 51 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 18 deletions(-)

diff --git a/block/bochs.c b/block/bochs.c
index af8b7ab..f0e18c0 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -104,6 +104,7 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
 
     bs->read_only = 1; // no write support yet
+    bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
 
     ret = bdrv_pread(bs->file->bs, 0, &bochs, sizeof(bochs));
     if (ret < 0) {
@@ -221,38 +222,52 @@ static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
     return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
 }
 
-static int bochs_read(BlockDriverState *bs, int64_t sector_num,
-                    uint8_t *buf, int nb_sectors)
+static int coroutine_fn
+bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                QEMUIOVector *qiov, int flags)
 {
+    BDRVBochsState *s = bs->opaque;
+    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
+    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    uint64_t bytes_done = 0;
+    QEMUIOVector local_qiov;
     int ret;
 
+    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
+    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
+
+    qemu_iovec_init(&local_qiov, qiov->niov);
+    qemu_co_mutex_lock(&s->lock);
+
     while (nb_sectors > 0) {
         int64_t block_offset = seek_to_sector(bs, sector_num);
         if (block_offset < 0) {
-            return block_offset;
-        } else if (block_offset > 0) {
-            ret = bdrv_pread(bs->file->bs, block_offset, buf, 512);
+            ret = block_offset;
+            goto fail;
+        }
+
+        qemu_iovec_reset(&local_qiov);
+        qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
+
+        if (block_offset > 0) {
+            ret = bdrv_co_preadv(bs->file->bs, block_offset, 512,
+                                 &local_qiov, 0);
             if (ret < 0) {
-                return ret;
+                goto fail;
             }
         } else {
-            memset(buf, 0, 512);
+            qemu_iovec_memset(&local_qiov, 0, 0, 512);
         }
         nb_sectors--;
         sector_num++;
-        buf += 512;
+        bytes_done += 512;
     }
-    return 0;
-}
 
-static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num,
-                                      uint8_t *buf, int nb_sectors)
-{
-    int ret;
-    BDRVBochsState *s = bs->opaque;
-    qemu_co_mutex_lock(&s->lock);
-    ret = bochs_read(bs, sector_num, buf, nb_sectors);
+    ret = 0;
+fail:
     qemu_co_mutex_unlock(&s->lock);
+    qemu_iovec_destroy(&local_qiov);
+
     return ret;
 }
 
@@ -267,7 +282,7 @@ static BlockDriver bdrv_bochs = {
     .instance_size	= sizeof(BDRVBochsState),
     .bdrv_probe		= bochs_probe,
     .bdrv_open		= bochs_open,
-    .bdrv_read          = bochs_co_read,
+    .bdrv_co_preadv = bochs_co_preadv,
     .bdrv_close		= bochs_close,
 };
 
-- 
1.8.3.1