Re: [Qemu-devel] [PATCH V9 00/11] Quorum block driver

[Benoît Canet]

Le Tuesday 29 Oct 2013 à 18:56:34 (+0100), Max Reitz a écrit :
> Am 29.10.2013 18:55, schrieb Max Reitz:
> > Am 29.10.2013 08:59, schrieb Benoît Canet:
> >> Le Friday 04 Oct 2013 à 16:31:56 (+0200), Max Reitz a écrit :
> >>> On 2013-10-02 14:39, Benoît Canet wrote:
> >>>> It must be applied on top of "block: Add 
> >>>> BlockDriver.bdrv_check_ext_snapshot."
> >>>>
> >>>> 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.
> >>>>
> >>>> v9: integrate latests comments from kevin
> >>>>
> >>>> Benoît Canet (11):
> >>>>   quorum: Create quorum.c, add QuorumSingleAIOCB and QuorumAIOCB.
> >>>>   quorum: Create BDRVQuorumState and BlkDriver and do init.
> >>>>   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_get_block_status.
> >>>>   quorum: Add quorum_co_flush().
> >>>>   quorum: Add quorum_open() and quorum_close().
> >>>>
> >>>>  block/Makefile.objs       |    1 +
> >>>>  block/blkverify.c         |  108 +----
> >>>>  block/quorum.c            | 1035 
> >>>> +++++++++++++++++++++++++++++++++++++++++++++
> >>>>  configure                 |   36 ++
> >>>>  include/monitor/monitor.h |    2 +
> >>>>  include/qemu-common.h     |    2 +
> >>>>  monitor.c                 |    2 +
> >>>>  util/iov.c                |  103 +++++
> >>>>  8 files changed, 1183 insertions(+), 106 deletions(-)
> >>>>  create mode 100644 block/quorum.c
> >>>>
> >>> Could you add a qemu-iotest if possible?
> >> I don't see how to specify quorum to qemu-io for bytes checking.
> >>
> >> Best regards
> >>
> >> Benoît
> > As of commit b543c5cd, you can pass options to the block driver through
> > qemu-io -c open. The problem for quorum is that it cannot handle the
> > filename option (which qemu-io will always set). I've attached a diff to
> > change this behavior (which makes the path parameter for open optional
> > and passes NULL to bdrv_open if it is not given). You're free to make
> > use of it. ;-)
> >
> > If this diff is applied, you can invoke qemu-io with quorum for example
> > as following:
> > qemu-io -c 'open -o
> > file.driver=quorum,file.children.0.file.filename=[Image
> > 1],file.children.1.file.filename=[Image 2],file.vote_threshold=[x]'
> >
> > Max
> 
> Obviously forgot to attach the diff.
> 
> Max

> diff --git a/qemu-io.c b/qemu-io.c
> index 3b3340a..4d0e9f6 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -57,8 +57,13 @@ static int openfile(char *name, int flags, int growable, 
> QDict *opts)
>  
>      if (growable) {
>          if (bdrv_file_open(&qemuio_bs, name, opts, flags, &local_err)) {
> -            fprintf(stderr, "%s: can't open device %s: %s\n", progname, name,
> -                    error_get_pretty(local_err));
> +            if (name) {
> +                fprintf(stderr, "%s: can't open device %s: %s\n", progname,
> +                        name, error_get_pretty(local_err));
> +            } else {
> +                fprintf(stderr, "%s: can't open device: %s\n", progname,
> +                        error_get_pretty(local_err));
> +            }
>              error_free(local_err);
>              return 1;
>          }
> @@ -66,8 +71,13 @@ static int openfile(char *name, int flags, int growable, 
> QDict *opts)
>          qemuio_bs = bdrv_new("hda");
>  
>          if (bdrv_open(qemuio_bs, name, opts, flags, NULL, &local_err) < 0) {
> -            fprintf(stderr, "%s: can't open device %s: %s\n", progname, name,
> -                    error_get_pretty(local_err));
> +            if (name) {
> +                fprintf(stderr, "%s: can't open device %s: %s\n", progname,
> +                        name, error_get_pretty(local_err));
> +            } else {
> +                fprintf(stderr, "%s: can't open device: %s\n", progname,
> +                        error_get_pretty(local_err));
> +            }
>              error_free(local_err);
>              bdrv_unref(qemuio_bs);
>              qemuio_bs = NULL;
> @@ -127,6 +137,7 @@ static int open_f(BlockDriverState *bs, int argc, char 
> **argv)
>      int c;
>      QemuOpts *qopts;
>      QDict *opts = NULL;
> +    char *filename = NULL;
>  
>      while ((c = getopt(argc, argv, "snrgo:")) != EOF) {
>          switch (c) {
> @@ -160,11 +171,13 @@ static int open_f(BlockDriverState *bs, int argc, char 
> **argv)
>          flags |= BDRV_O_RDWR;
>      }
>  
> -    if (optind != argc - 1) {
> +    if (optind == argc - 1) {
> +        filename = argv[optind];
> +    } else if (optind < argc - 1) {
>          return qemuio_command_usage(&open_cmd);
>      }
>  
> -    return openfile(argv[optind], flags, growable, opts);
> +    return openfile(filename, flags, growable, opts);
>  }
>  
>  static int quit_f(BlockDriverState *bs, int argc, char **argv)

Thanks a lot.

Best regards

Benoît