On Wed, 2010-12-15 at 14:31 -0500, Trond Myklebust wrote: > On Wed, 2010-12-15 at 20:51 +0200, Benny Halevy wrote: > > Eventually, when CB_LAYOUTRECALL is clear to go sending the LAYOUTRETURN > > or replying with CB_NOMATCHING_LAYOUT (assuming no I/O error to report > > for pnfs-obj) should be equivalent [note: need errata to clarify the > > resulting stateid after NOMATCHING_LAYOUT]. > > Is this the serialization "crap" you're talking about? > > What makes checking the conditions for returning NFS4ERR_DELAY to > > CB_LAYOUTRECALL so different from implementing a barrier and doing the > > returns asynchronously with the CB_LAYOUTRECALL? > > "CB_LAYOUTRECALL request processing MUST be processed in "seqid" order > at all times." (section 12.5.3). > > In other words, you cannot just 'do the returns asynchronously': the > CB_LAYOUTRECALL requests are required by the protocol to be processed in > order, which means that you must serialise those LAYOUTRETURN calls to > ensure that they all happen in the order the wretched server expects. BTW: one consequence of the way the protocol was written is that you can't just throw out a LAYOUTRETURN for the entire file if the server just recalls a segment. Instead, you have to first return the segment, then send the LAYOUTRETURN for the entire file. That part of the protocol is just one insane idea after another... -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
