block: Fix comment for bdrv_co_get_block_status

It returns more information than binary, fix the comment.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

block.c

@@ -3877,9 +3877,9 @@ typedef struct BdrvCoGetBlockStatusData {
 } BdrvCoGetBlockStatusData;
 
 /*
- * Returns true iff the specified sector is present in the disk image. Drivers
- * not implementing the functionality are assumed to not support backing files,
- * hence all their sectors are reported as allocated.
+ * Returns the allocation status of the specified sectors.
+ * Drivers not implementing the functionality are assumed to not support
+ * backing files, hence all their sectors are reported as allocated.
  *
  * If 'sector_num' is beyond the end of the disk image the return value is 0
  * and 'pnum' is set to 0.

include/block/block.h

@@ -83,7 +83,9 @@ typedef enum {
 #define BDRV_SECTOR_SIZE   (1ULL << BDRV_SECTOR_BITS)
 #define BDRV_SECTOR_MASK   ~(BDRV_SECTOR_SIZE - 1)
 
-/* BDRV_BLOCK_DATA: data is read from bs->file or another file
+/*
+ * Allocation status flags
+ * BDRV_BLOCK_DATA: data is read from bs->file or another file
  * BDRV_BLOCK_ZERO: sectors read as zero
  * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
  * BDRV_BLOCK_ALLOCATED: the content of the block is determined by this