block/vmdk: Improve error messages on extent write error

vmdk_init_extent() reports blk_co_pwrite() failure to its caller as

    An IO error has occurred

The errno code returned by blk_co_pwrite() is lost.

Improve this to

    failed to write VMDK <what>: <description of errno>

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240513141703.549874-4-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

block/vmdk.c

@@ -28,7 +28,6 @@
 #include "block/block_int.h"
 #include "sysemu/block-backend.h"
 #include "qapi/qmp/qdict.h"
-#include "qapi/qmp/qerror.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "qemu/option.h"
@@ -2278,12 +2277,12 @@ vmdk_init_extent(BlockBackend *blk, int64_t filesize, bool flat, bool compress,
     /* write all the data */
     ret = blk_co_pwrite(blk, 0, sizeof(magic), &magic, 0);
     if (ret < 0) {
-        error_setg(errp, QERR_IO_ERROR);
+        error_setg_errno(errp, -ret, "failed to write VMDK magic");
         goto exit;
     }
     ret = blk_co_pwrite(blk, sizeof(magic), sizeof(header), &header, 0);
     if (ret < 0) {
-        error_setg(errp, QERR_IO_ERROR);
+        error_setg_errno(errp, -ret, "failed to write VMDK header");
         goto exit;
     }
 
@@ -2303,7 +2302,7 @@ vmdk_init_extent(BlockBackend *blk, int64_t filesize, bool flat, bool compress,
     ret = blk_co_pwrite(blk, le64_to_cpu(header.rgd_offset) * BDRV_SECTOR_SIZE,
                         gd_buf_size, gd_buf, 0);
     if (ret < 0) {
-        error_setg(errp, QERR_IO_ERROR);
+        error_setg_errno(errp, -ret, "failed to write VMDK grain directory");
         goto exit;
     }
 
@@ -2315,7 +2314,8 @@ vmdk_init_extent(BlockBackend *blk, int64_t filesize, bool flat, bool compress,
     ret = blk_co_pwrite(blk, le64_to_cpu(header.gd_offset) * BDRV_SECTOR_SIZE,
                         gd_buf_size, gd_buf, 0);
     if (ret < 0) {
-        error_setg(errp, QERR_IO_ERROR);
+        error_setg_errno(errp, -ret,
+                         "failed to write VMDK backup grain directory");
     }
 
     ret = 0;