Add more resiliency to disk image format handling - #7728
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likebreath merged 4 commits intoFeb 19, 2026
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- vmm: Improve resiliency of image type handling
- vmm, virtio-devices: Deny zero sector writes for autodetected raw images
- vhost_user_blk: Disable use of backing files in test implementation
- virtio-devices, block: Reject sector 0 discard/"write zeroes" requests
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Add an image_type to DiskConfig to specify the image type. If none is specified autodetect the image type but disable potentially unsafe behaviour in the QCOW2 backend by disabling the backing file support. If the image type is autodetected then fix it in the config so that it will be persistant across reboots and migrations/snapshot & restores. This also handles the case where the image type was not specified as part of the disk configuration. Signed-off-by: Rob Bradford <[email protected]>
If the disk image was autodetected to raw (not specified with image_type = 0) then in the virtio-block subsystem generate errors for writes to block 0 (treat as if read-only). This gives an immediate error vs using the image implementations in the block subsystem. Signed-off-by: Rob Bradford <[email protected]>
Remove the use of QCOW2 backing files in the test implementation used for CI. Signed-off-by: Rob Bradford <[email protected]>
As well as rejecting writes to sector 0 in the case of raw files where the user hasn't specified the image_type also reject virtio requests of type discard and write_zeroes. Signed-off-by: Rob Bradford <[email protected]>
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