diff options
| author | Daniel P. Berrange <berrange@redhat.com> | 2016-03-21 14:11:42 +0000 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2016-03-30 11:59:32 +0200 |
| commit | abb06c5ac1c86e747bbe08bf7b5b69723ad69832 (patch) | |
| tree | 227d67569c4069dbb356410cbf77e0544224bda8 /include | |
| parent | 543021569978c908fccff235bf90fc803e6fed1d (diff) | |
block: add flag to indicate that no I/O will be performed
When opening an image it is useful to know whether the caller
intends to perform I/O on the image or not. In the case of
encrypted images this will allow the block driver to avoid
having to prompt for decryption keys when we merely want to
query header metadata about the image. eg qemu-img info
This flag is enforced at the top level only, since even if
we don't want todo I/O on the 'qcow2' file payload, the
underlying 'file' driver will still need todo I/O to read
the qcow2 header, for example.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/block/block.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/block/block.h b/include/block/block.h index a48ad49397..c236e1d813 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -93,6 +93,7 @@ typedef struct HDGeometry { #define BDRV_O_PROTOCOL 0x8000 /* if no block driver is explicitly given: select an appropriate protocol driver, ignoring the format layer */ +#define BDRV_O_NO_IO 0x10000 /* don't initialize for I/O */ #define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH) |