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| 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 /block.c | |
| parent | 543021569978c908fccff235bf90fc803e6fed1d (diff) | |
| download | qemu-abb06c5ac1c86e747bbe08bf7b5b69723ad69832.tar.gz qemu-abb06c5ac1c86e747bbe08bf7b5b69723ad69832.tar.bz2 qemu-abb06c5ac1c86e747bbe08bf7b5b69723ad69832.zip | |
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 'block.c')
| -rw-r--r-- | block.c | 5 |
1 files changed, 3 insertions, 2 deletions
@@ -702,7 +702,8 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options, flags |= BDRV_O_UNMAP; /* Clear flags that only apply to the top layer */ - flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); + flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ | + BDRV_O_NO_IO); *child_flags = flags; } @@ -722,7 +723,7 @@ static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options, child_file.inherit_options(child_flags, child_options, parent_flags, parent_options); - *child_flags &= ~BDRV_O_PROTOCOL; + *child_flags &= ~(BDRV_O_PROTOCOL | BDRV_O_NO_IO); } const BdrvChildRole child_format = { |