On Sat, Jan 19, 2013 at 1:30 AM, Benoît Canet <ben...@irqsave.net> wrote: > This patchset is rebased on top of "cutils: unsigned int parsing functions" > by "Eduardo Habkost". > > This patchset create a block driver implementing a quorum using total qemu > disk > images. Writes are mirrored on the $total files. > For the reading part the $total files are read at the same time and a vote is > done to determine if a qiov version is present $threshold or more times. It > then > return this majority version to the upper layers. > When i < $threshold versions of the data are returned by the lower layer the > quorum is broken and the read return -EIO. > > The goal of this patchset is to be turned in a QEMU block filter living just > above raw-*.c and below qcow2/qed when the required infrastructure will be > done. > > Main use of this feature will be people using NFS appliances which can be > subjected to bitflip errors. > > This patchset can be used to replace blkverify and the out of tree blkmirror. > > usage: -drive > file=quorum:threshold/total:image_1.raw:...:image_total.raw,if=virtio,cache=none I don't know if the following case can be handled correctly. For example, quorum:2/3:image1.raw:image2.raw:image3.raw Let us assume that some data in image2.raw and image3.raw get corrupted, and the two images are now completely identical; while image1.raw doesn't get corrupted. In this case, how will your vote method know if which image gets corrupted and which image doesn't?
> > in this version: > parse total and threshold with parse_uint [Eric] > return proper qerrors in quorum_open [Eric] > Use sha256 for comparing blocks [Eric] > Update the rest of the voting function to the new way of doing [Benoît] > > V6: > fix commit message of "quorum: Add quorum_open() and quorum_close()." > [Eric] > return error after a vote in quorum_co_flush [Eric] > Fix bitrot caused by headers and structures renaming [Benoît] > initialize finished to NULL to prevent crash [Benoît] > convert internal quorum code to uint64_t instead of int64_t [Benoît] > > V5: > > Eric Blake: revert back separator to ":" > rewrite quorum_getlength > > Benoît Canet: use memcmp to compare iovec excepted for the blkverify case > use strstart to parse argument in open > > > Benoît Canet (11): > quorum: Create quorum.c, add QuorumSingleAIOCB and QuorumAIOCB. > quorum: Create BDRVQuorumState and BlkDriver and do init. > quorum: Add quorum_open() and quorum_close(). > quorum: Add quorum_aio_writev and its dependencies. > blkverify: Extract qemu_iovec_clone() and qemu_iovec_compare() from > blkverify. > quorum: Add quorum_aio_readv. > quorum: Add quorum mechanism. > quorum: Add quorum_getlength(). > quorum: Add quorum_invalidate_cache(). > quorum: Add quorum_co_is_allocated. > quorum: Add quorum_co_flush(). > > block/Makefile.objs | 1 + > block/blkverify.c | 108 +------ > block/quorum.c | 789 > +++++++++++++++++++++++++++++++++++++++++++++++++ > configure | 22 ++ > include/qemu-common.h | 2 + > util/iov.c | 103 +++++++ > 6 files changed, 919 insertions(+), 106 deletions(-) > create mode 100644 block/quorum.c > > -- > 1.7.10.4 > > -- Regards, Zhi Yong Wu
