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Re: [Qemu-devel] [PATCH v7 0/3] block: Fix unaligned bdrv_aio_write_zero
Re: [Qemu-devel] [PATCH v7 0/3] block: Fix unaligned bdrv_aio_write_zeroes
Mon, 18 May 2015 11:01:02 +0100
On Wed, May 13, 2015 at 01:11:58PM +0000, Fam Zheng wrote:
> v7: Add Kevin's rev-by in patch 1 and 3.
> Address Stefan's and Kevin's comments on patch 2:
> - Don't duplicate tracked_request_begin and tracked_request_end;
> - Don't forget to remove debug printf;
> - Call qemu_vfree unconditionally;
> - Don't serialize aligned part of the zero write req;
> An unaligned zero write causes NULL deferencing in bdrv_co_do_pwritev. That
> path is reachable from bdrv_co_write_zeroes and bdrv_aio_write_zeroes.
> You can easily trigger through the former with qemu-io, as the test case added
> by 61815d6e0aa. For bdrv_aio_write_zeroes, in common cases there's always a
> format driver (which uses 512 alignment), so it would be much rarer to have
> unaligned requests (only concerning top level here, when the request goes down
> to bs->file, where for example the alignment is 4k, it would then be calling
> bdrv_co_write_zeroes because it's in a coroutine).
> fc3959e4669a1c fixed bdrv_co_write_zeroes but not bdrv_aio_write_zeroes. The
> lattern is the actually used one by device model. Revert the previous fix, do
> it in bdrv_co_do_pwritev, to cover both paths.
> Fam Zheng (3):
> Revert "block: Fix unaligned zero write"
> block: Fix NULL deference for unaligned write if qiov is NULL
> qemu-iotests: Test unaligned sub-block zero write
> block/io.c | 142
> tests/qemu-iotests/033 | 13 +++++
> tests/qemu-iotests/033.out | 30 ++++++++++
> 3 files changed, 144 insertions(+), 41 deletions(-)
Thanks, applied to my block tree:
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