Hi Dave and Eric, On 2019/8/1 22:26, Dr. David Alan Gilbert wrote: > * Dr. David Alan Gilbert (dgilb...@redhat.com) wrote: >> * Eric Blake (ebl...@redhat.com) wrote: >>> On 7/29/19 7:27 PM, piaojun wrote: >>>> Use F_GETLK for fcntl when F_OFD_GETLK not defined. >>> >>> Which system are you hitting this problem on? >>> >>> The problem with F_GETLK is that it is NOT as safe as F_OFD_GETLK. >>> >>> We already have fcntl_op_getlk and qemu_probe_lock_ops() in util/osdep.c >>> to not only determine which form to use, but also to emit a warning to >>> the end user if we had to fall back to the unsafe F_GETLK. Why is your >>> code not reusing that logic? >>> >>>> >>>> Signed-off-by: Jun Piao <piao...@huawei.com> >>>> --- >>>> contrib/virtiofsd/passthrough_ll.c | 9 +++++++++ >>>> 1 file changed, 9 insertions(+) >>>> >>>> diff --git a/contrib/virtiofsd/passthrough_ll.c >>>> b/contrib/virtiofsd/passthrough_ll.c >>>> index 9ae1381..757785b 100644 >>>> --- a/contrib/virtiofsd/passthrough_ll.c >>>> +++ b/contrib/virtiofsd/passthrough_ll.c >>>> @@ -1619,7 +1619,11 @@ static void lo_getlk(fuse_req_t req, fuse_ino_t ino, >>>> return; >>>> } >>>> >>>> +#ifdef F_OFD_GETLK >>>> ret = fcntl(plock->fd, F_OFD_GETLK, lock); >>>> +#else >>>> + ret = fcntl(plock->fd, F_GETLK, lock); >>>> +#endif >>> >>> Hmm. Since this is in contrib, you are trying to compile something that >>> is independent of util/osdep.c (at least, I assume that's the case, as >>> contrib/virtiofsd/ is not even part of qemu.git master yet - in which >>> case, why is this not being squashed in to the patch introducing that >>> file, rather than sent standalone). On the other hand, that raises the >>> question - who is trying to use virtiofsd on a kernel that is too old to >>> provid F_OFD_GETLK? Isn't the whole point of virtiofsd to be speeding >>> up modern usage, at which point an old kernel is just gumming up the >>> works? It seems like you are better off letting compilation fail on a >>> system that is too old to support decent F_OFD_GETLK, rather than >>> silently falling back to something that is unsafe. >> >> It is, but I guess the answer here is someone wanted to build on RHEL7. > > although looking at the tools it went in 7.6 > > Dave >
Yes, the compile error comes from kernel 3.10, and it seems necessary to solve this. I try to reuse qemu_lock_fd() to compat F_GETLK/F_SETLK, but its semantics differs from fcntl, so I think using #ifdef will be easier. We could delete F_GETLK/F_SETLK compat when virtiofsd is limited to be built in newer kernel. And I'm glad to hear from other developers. Thanks, Jun >> Dave >> >>> >>> -- >>> Eric Blake, Principal Software Engineer >>> Red Hat, Inc. +1-919-301-3226 >>> Virtualization: qemu.org | libvirt.org >>> >> >> >> >> >>> _______________________________________________ >>> Virtio-fs mailing list >>> virtio...@redhat.com >>> https://www.redhat.com/mailman/listinfo/virtio-fs >> >> -- >> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >> >> _______________________________________________ >> Virtio-fs mailing list >> virtio...@redhat.com >> https://www.redhat.com/mailman/listinfo/virtio-fs > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK > > _______________________________________________ > Virtio-fs mailing list > virtio...@redhat.com > https://www.redhat.com/mailman/listinfo/virtio-fs > . >
