Message ID | 20190515041541.12367-1-mreitz@redhat.com (mailing list archive) |
---|---|
Headers | show |
Series | block/file-posix: Fix unaligned O_DIRECT block status | expand |
Am 15.05.2019 um 06:15 hat Max Reitz geschrieben: > The user-visible problem: > $ echo > foo > $ qemu-img map --image-opts driver=file,filename=foo,cache.direct=on > Offset Length Mapped to File > qemu-img: block/io.c:2093: bdrv_co_block_status: Assertion `*pnum && > QEMU_IS_ALIGNED(*pnum, align) && align > offset - aligned_offset' > failed. > > The internal problem: file-posix truncates status requests to the EOF. > If the EOF is not aligned at the request_alignment, > bdrv_co_block_status() won't like that. > > See patch 1 for a deeper discussion (including two possible alternatives > how we could address the problem). > (As I note there, I’ve looked through all block drivers, and I didn’t > find any other which could have the same problem. gluster uses the same > block-status code, but it doesn’t set a request_alignment. NBD > force-aligns the server response in nbd_parse_blockstatus_payload(). > qcow2... Should be fine as long as no crypto driver has a block limit > exceeding the qcow2 cluster size. And so on.) > > Patch 2 adds a test. After writing that test, I noticed that we already > had one: 109 fails with -c none before patch 1. Er, well, at least the > new test is more succinct and has the correct default cache mode, so it > will actually do the test if you run ./check without enforcing any cache > on a filesystem that supports O_DIRECT. Thanks, applied to the block branch. Kevin