block: remove has_variable_length from BlockDriver

Fill in the field in BlockLimits directly for host devices, and
copy it from there for the raw format.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20230407153303.391121-5-pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/file-posix.c

@@ -3743,6 +3743,12 @@ static void cdrom_parse_filename(const char *filename, QDict *options,
 {
     bdrv_parse_filename_strip_prefix(filename, "host_cdrom:", options);
 }
+
+static void cdrom_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+    bs->bl.has_variable_length = true;
+    raw_refresh_limits(bs, errp);
+}
 #endif
 
 #ifdef __linux__
@@ -3838,14 +3844,13 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_co_preadv         = raw_co_preadv,
     .bdrv_co_pwritev        = raw_co_pwritev,
     .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
-    .bdrv_refresh_limits = raw_refresh_limits,
+    .bdrv_refresh_limits    = cdrom_refresh_limits,
     .bdrv_co_io_plug        = raw_co_io_plug,
     .bdrv_co_io_unplug      = raw_co_io_unplug,
     .bdrv_attach_aio_context = raw_aio_attach_aio_context,
 
     .bdrv_co_truncate                   = raw_co_truncate,
     .bdrv_co_getlength                  = raw_co_getlength,
-    .has_variable_length                = true,
     .bdrv_co_get_allocated_file_size    = raw_co_get_allocated_file_size,
 
     /* removable device support */
@@ -3967,14 +3972,13 @@ static BlockDriver bdrv_host_cdrom = {
     .bdrv_co_preadv         = raw_co_preadv,
     .bdrv_co_pwritev        = raw_co_pwritev,
     .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
-    .bdrv_refresh_limits = raw_refresh_limits,
+    .bdrv_refresh_limits    = cdrom_refresh_limits,
     .bdrv_co_io_plug        = raw_co_io_plug,
     .bdrv_co_io_unplug      = raw_co_io_unplug,
     .bdrv_attach_aio_context = raw_aio_attach_aio_context,
 
     .bdrv_co_truncate                   = raw_co_truncate,
     .bdrv_co_getlength                  = raw_co_getlength,
-    .has_variable_length                = true,
     .bdrv_co_get_allocated_file_size    = raw_co_get_allocated_file_size,
 
     /* removable device support */

block/file-win32.c

@@ -838,6 +838,7 @@ static void hdev_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     /* XXX Does Windows support AIO on less than 512-byte alignment? */
     bs->bl.request_alignment = 512;
+    bs->bl.has_variable_length = true;
 }
 
 static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
@@ -933,7 +934,6 @@ static BlockDriver bdrv_host_device = {
     .bdrv_attach_aio_context = raw_attach_aio_context,
 
     .bdrv_co_getlength                = raw_co_getlength,
-    .has_variable_length              = true,
     .bdrv_co_get_allocated_file_size  = raw_co_get_allocated_file_size,
 };
 

block/io.c

@@ -182,8 +182,6 @@ void bdrv_refresh_limits(BlockDriverState *bs, Transaction *tran, Error **errp)
                                 drv->bdrv_aio_preadv ||
                                 drv->bdrv_co_preadv_part) ? 1 : 512;
 
-    bs->bl.has_variable_length = drv->has_variable_length;
-
     /* Take some limits from the children as a default */
     have_limits = false;
     QLIST_FOREACH(c, &bs->children, next) {

block/raw-format.c

@@ -377,6 +377,8 @@ raw_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 
 static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 {
+    bs->bl.has_variable_length = bs->file->bs->bl.has_variable_length;
+
     if (bs->probed) {
         /* To make it easier to protect the first sector, any probed
          * image is restricted to read-modify-write on sub-sector
@@ -623,7 +625,6 @@ BlockDriver bdrv_raw = {
     .bdrv_co_truncate     = &raw_co_truncate,
     .bdrv_co_getlength    = &raw_co_getlength,
     .is_format            = true,
-    .has_variable_length  = true,
     .bdrv_measure         = &raw_measure,
     .bdrv_co_get_info     = &raw_co_get_info,
     .bdrv_refresh_limits  = &raw_refresh_limits,

include/block/block_int-common.h

@@ -158,8 +158,6 @@ struct BlockDriver {
      */
     bool supports_backing;
 
-    bool has_variable_length;
-
     /*
      * Drivers setting this field must be able to work with just a plain
      * filename with '<protocol_name>:' as a prefix, and no other options.