block: qcow: Add read support for zero bit in L2 entries#7627
Merged
likebreath merged 2 commits intocloud-hypervisor:mainfrom Jan 22, 2026
Merged
block: qcow: Add read support for zero bit in L2 entries#7627likebreath merged 2 commits intocloud-hypervisor:mainfrom
likebreath merged 2 commits intocloud-hypervisor:mainfrom
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Implement read support for bit 0 in QCOW2 L2 table entries. When this flag is set, the cluster reads as zeros without accessing disk. This improves compatibility with QCOW2 images that use this optimization. According to the QCOW2 specification, bit 0 of the standard cluster descriptor indicates that the cluster reads as zeros. Unlike l2_entry == 0 indicating a completely unallocated entry, bit 0 can be set on an allocated cluster. Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Add test for l2_entry_is_zero() and related helper functions. Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
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phip1611
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likebreath
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Jan 22, 2026
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liuw
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Feb 10, 2026
Since kernel commit 6693731487a8 ("vsock/virtio: Allocate nonlinear SKBs
for handling large transmit buffers"), a large vsock packet can be split
into multiple descriptors.
If we encounter such TX packets, pull the content into an owned buffer.
Fixes: cloud-hypervisor#7627
Signed-off-by: Wei Liu <liuwe@microsoft.com>
liuw
added a commit
to liuw/cloud-hypervisor
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Feb 10, 2026
Since kernel commit 6693731487a8 ("vsock/virtio: Allocate nonlinear SKBs
for handling large transmit buffers"), a large vsock packet can be split
into multiple descriptors.
If we encounter such TX packets, pull the content into an owned buffer.
Fixes: cloud-hypervisor#7627
Signed-off-by: Wei Liu <liuwe@microsoft.com>
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Implements support for bit 0 in QCOW2 v3 L2 table entries. When set, the cluster reads as zeros without disk access, improving compatibility with QCOW2 images using this optimization.