block: fix short read and short write in AsyncAdaptor #6884
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The original code relied on the default `read_vectored` or `write_vectored` implementations from the standard library. The default implementation of those functions only uses the first non-empty buffer. That's not correct when there are more than one buffers. Fixes: cloud-hypervisor#6876 Signed-off-by: Wei Liu <[email protected]>
russell-islam
approved these changes
Dec 21, 2024
rbradford
approved these changes
Dec 21, 2024
| .map_err(AsyncIoError::ReadVectored)? | ||
| let mut r = 0; | ||
| for b in slices.iter_mut() { | ||
| r += file.read(b).map_err(AsyncIoError::ReadVectored)?; |
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Would be nice to think about using libc::readv to minimise the syscalls.
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That cannot be done easily. VHDX and QCOW2 disks are not regular files. Their read and write implementation does a bunch of calculation before reading and writing the actual file on disk.
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@liuw Thank you for fixing the issue. Please add a label |
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The original code relied on the default
read_vectoredorwrite_vectoredimplementations from the standard library.The default implementation of those functions only uses the first non-empty buffer. That's not correct when there are more than one buffers.
Fixes: #6876
This should be backported.