1 files changed, 29 insertions, 1 deletions

diff --git a/block.c b/block.c
index e655052..1615d89 100644
--- a/block.c
+++ b/block.c
@@ -2571,7 +2571,35 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
         }
     }
 
-    ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
+    if (!(bs->zero_beyond_eof && bs->growable)) {
+        ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
+    } else {
+        /* Read zeros after EOF of growable BDSes */
+        int64_t len, total_sectors, max_nb_sectors;
+
+        len = bdrv_getlength(bs);
+        if (len < 0) {
+            ret = len;
+            goto out;
+        }
+
+        total_sectors = len >> BDRV_SECTOR_BITS;
+        max_nb_sectors = MAX(0, total_sectors - sector_num);
+        if (max_nb_sectors > 0) {
+            ret = drv->bdrv_co_readv(bs, sector_num,
+                                     MIN(nb_sectors, max_nb_sectors), qiov);
+        } else {
+            ret = 0;
+        }
+
+        /* Reading beyond end of file is supposed to produce zeroes */
+        if (ret == 0 && total_sectors < sector_num + nb_sectors) {
+            uint64_t offset = MAX(0, total_sectors - sector_num);
+            uint64_t bytes = (sector_num + nb_sectors - offset) *
+                              BDRV_SECTOR_SIZE;
+            qemu_iovec_memset(qiov, offset * BDRV_SECTOR_SIZE, 0, bytes);
+        }
+    }
 
 out:
     tracked_request_end(&req);