On Thu, Sep 29, 2016 at 9:49 PM, Ning Yao <zay11022@xxxxxxxxx> wrote: > XFS has #fiemap extent intervals limitted in kernel， so if we do not > use seek_data, seek_hole. It will lead to getting a wrong fiemap > (absence of some extents) from a large object. It is actually not > security before Jewel with enabling filestore_seek_data_hole. I'm not sure your problem. We already have known fiemap bug in legacy os. And we also fixed fiemap usage in filestore layer. If possible, we'd like to test this. > Regards > Ning Yao > > > 2016-09-29 10:27 GMT+08:00 Haomai Wang <haomai@xxxxxxxx>: >> On Thu, Sep 29, 2016 at 10:25 AM, Haomai Wang <haomai@xxxxxxxx> wrote: >>> On Thu, Sep 29, 2016 at 12:26 AM, Ning Yao <zay11022@xxxxxxxxx> wrote: >>>> Hi, >>>> >>>> As lots of fiemap issues in XFS, fiemap is default disabled now, >>>> especially in Hammer, before seek_data, seek_hole is added. >>>> >>>> But disabling fiemap feature will cause a small sparse object become a >>>> large full object during PushOps, which may lead to notably data >>>> in-balance between OSD, especially on the new added OSD during data >>>> rebalance. With those full objects, some OSDs may simultaneously >>>> becomes full. >>> >>> Until now, I don't know existing problem with fiemap enabled in >>> hammer. Although we find it maybe problem when clone to a existing >>> overlap data range, but it won't exists in real case. >> >> Hmm, I can't guarantee this... I only means if you want to have sparse >> object, you can enable this. .... >> >>> >>>> >>>> Furthermore, currently, it is impossible to make the full objects >>>> sparse again if we enable the fiemap feature in the future. >>>> >>>> So I think if any solutions to make a full object back to a sparse >>>> object again? One of the idea is to check whether the content in the >>>> object contains consecutive zero and punch zeros for those object >>>> during deep-scrub, is that possible and reasonable? >>> >>> Obviously it's a complex thing more than we get. >>> >>>> >>>> >>>> >>>> Regards >>>> Ning Yao >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
