diff options
Diffstat (limited to 'include/block/block.h')
| -rw-r--r-- | include/block/block.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/include/block/block.h b/include/block/block.h index cdec363..3894edd 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -54,8 +54,12 @@ typedef enum { BDRV_REQ_FUA = 0x10, BDRV_REQ_WRITE_COMPRESSED = 0x20, + /* Signifies that this write request will not change the visible disk + * content. */ + BDRV_REQ_WRITE_UNCHANGED = 0x40, + /* Mask of valid flags */ - BDRV_REQ_MASK = 0x3f, + BDRV_REQ_MASK = 0x7f, } BdrvRequestFlags; typedef struct BlockSizes { @@ -205,6 +209,9 @@ enum { * This permission (which is weaker than BLK_PERM_WRITE) is both enough and * required for writes to the block node when the caller promises that * the visible disk content doesn't change. + * + * As the BLK_PERM_WRITE permission is strictly stronger, either is + * sufficient to perform an unchanging write. */ BLK_PERM_WRITE_UNCHANGED = 0x04, |