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-rw-r--r--include/block/block.h10
1 files changed, 7 insertions, 3 deletions
diff --git a/include/block/block.h b/include/block/block.h
index a193545b6a..81fcaad5ac 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -72,9 +72,11 @@ typedef enum {
     BDRV_REQ_NO_FALLBACK        = 0x100,
 
     /*
-     * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_READ
-     * on read request and means that caller doesn't really need data to be
-     * written to qiov parameter which may be NULL.
+     * BDRV_REQ_PREFETCH makes sense only in the context of copy-on-read
+     * (i.e., together with the BDRV_REQ_COPY_ON_READ flag or when a COR
+     * filter is involved), in which case it signals that the COR operation
+     * need not read the data into memory (qiov) but only ensure they are
+     * copied to the top layer (i.e., that COR operation is done).
      */
     BDRV_REQ_PREFETCH  = 0x200,
 
@@ -358,6 +360,8 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
                  Error **errp);
 void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
                        Error **errp);
+BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *node_options,
+                                   int flags, Error **errp);
 
 int bdrv_parse_aio(const char *mode, int *flags);
 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough);