block: Add @exact parameter to bdrv_co_truncate()

We have two drivers (iscsi and file-posix) that (in some cases) return
success from their .bdrv_co_truncate() implementation if the block
device is larger than the requested offset, but cannot be shrunk.  Some
callers do not want that behavior, so this patch adds a new parameter
that they can use to turn off that behavior.

This patch just adds the parameter and lets the block/io.c and
block/block-backend.c functions pass it around.  All other callers
always pass false and none of the implementations evaluate it, so that
this patch does not change existing behavior.  Future patches take care
of that.

Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-5-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/block/vmdk.c b/block/vmdk.c
index fed3b50c8a..20e909d997 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2076,7 +2076,7 @@ vmdk_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
                 return length;
             }
             length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE);
-            ret = bdrv_truncate(s->extents[i].file, length,
+            ret = bdrv_truncate(s->extents[i].file, length, false,
                                 PREALLOC_MODE_OFF, NULL);
             if (ret < 0) {
                 return ret;
@@ -2118,7 +2118,7 @@ static int vmdk_init_extent(BlockBackend *blk,
     int gd_buf_size;
 
     if (flat) {
-        ret = blk_truncate(blk, filesize, PREALLOC_MODE_OFF, errp);
+        ret = blk_truncate(blk, filesize, false, PREALLOC_MODE_OFF, errp);
         goto exit;
     }
     magic = cpu_to_be32(VMDK4_MAGIC);
@@ -2181,7 +2181,7 @@ static int vmdk_init_extent(BlockBackend *blk,
         goto exit;
     }
 
-    ret = blk_truncate(blk, le64_to_cpu(header.grain_offset) << 9,
+    ret = blk_truncate(blk, le64_to_cpu(header.grain_offset) << 9, false,
                        PREALLOC_MODE_OFF, errp);
     if (ret < 0) {
         goto exit;
@@ -2523,7 +2523,7 @@ static int coroutine_fn vmdk_co_do_create(int64_t size,
     /* bdrv_pwrite write padding zeros to align to sector, we don't need that
      * for description file */
     if (desc_offset == 0) {
-        ret = blk_truncate(blk, desc_len, PREALLOC_MODE_OFF, errp);
+        ret = blk_truncate(blk, desc_len, false, PREALLOC_MODE_OFF, errp);
         if (ret < 0) {
             goto exit;
         }