Am 30.08.2012 20:47, schrieb Jeff Cody:
> I believe the bs->keep_read_only flag is supposed to reflect
> the initial open state of the device. If the device is initially
> opened R/O, then commit operations, or reopen operations changing
> to R/W, are prohibited.
>
> Currently, the keep_read_only flag is only accurate for the active
> layer, and its backing file. Subsequent images end up always having
> the keep_read_only flag set.
>
> For instance, what happens now:
>
> [ base ] kro = 1, ro = 1
> |
> v
> [ snap-1 ] kro = 1, ro = 1
> |
> v
> [ snap-2 ] kro = 0, ro = 1
> |
> v
> [ active ] kro = 0, ro = 0
>
> What we want:
>
> [ base ] kro = 0, ro = 1
> |
> v
> [ snap-1 ] kro = 0, ro = 1
> |
> v
> [ snap-2 ] kro = 0, ro = 1
> |
> v
> [ active ] kro = 0, ro = 0
>
> Signed-off-by: Jeff Cody <jc...@redhat.com>
> ---
> block.c | 16 +++++++---------
> block.h | 1 +
> 2 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/block.c b/block.c
> index 470bdcc..e31b76f 100644
> --- a/block.c
> +++ b/block.c
> @@ -655,7 +655,7 @@ static int bdrv_open_common(BlockDriverState *bs, const
> char *filename,
> * Clear flags that are internal to the block layer before opening the
> * image.
> */
> - open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
> + open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_ALLOW_RDWR);
>
> /*
> * Snapshots should be writable.
> @@ -664,8 +664,6 @@ static int bdrv_open_common(BlockDriverState *bs, const
> char *filename,
> open_flags |= BDRV_O_RDWR;
> }
>
> - bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);
> -
> /* Open the image, either directly or using a protocol */
> if (drv->bdrv_file_open) {
> ret = drv->bdrv_file_open(bs, filename, open_flags);
> @@ -804,6 +802,12 @@ int bdrv_open(BlockDriverState *bs, const char
> *filename, int flags,
> goto unlink_and_fail;
> }
>
> + if (flags & BDRV_O_RDWR) {
> + flags |= BDRV_O_ALLOW_RDWR;
> + }
> +
> + bs->keep_read_only = !(flags & BDRV_O_ALLOW_RDWR);
Do we still need bs->keep_read_only or is it duplicated in
bs->open_flags now? We can convert all users in a follow-up patch.
Kevin
