NFS write gathering defers execution of NFS server write requests to wait
to see if additional write requests will arrive that can be coalesced and clustered with earlier ones. When doing so, it must determine whether the two requests are made by credentials with the same access writes, so as not to coalesce improperly. NFSW_SAMECRED() implements a test of two credentials using a binary compare. Replace NFSW_SAMECRED() macro with nfsrv_samecred() function, which is aware of the contents and layout of a struct ucred, rather than a simple binary compare. While the binary compare works when ucred is simply a zero'd and embedded 'struct ucred' in the NFS descriptor, it will work less well when the ucred associated with an NFS descriptor is "real", so has defined and populated reference count, mutex, etc. MFC after: 1 week Obtained from: TrustedBSD Project
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=145197
@ -275,10 +275,6 @@ extern int nfsd_head_flag;
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((o)->nd_eoff >= (n)->nd_off && \
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!bcmp((caddr_t)&(o)->nd_fh, (caddr_t)&(n)->nd_fh, NFSX_V3FH))
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#define NFSW_SAMECRED(o, n) \
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(!bcmp((caddr_t)&(o)->nd_cr, (caddr_t)&(n)->nd_cr, \
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sizeof (struct ucred)))
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/*
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* Defines for WebNFS
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*/
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@ -1300,6 +1300,28 @@ nfsrv_write(struct nfsrv_descript *nfsd, struct nfssvc_sock *slp,
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return(error);
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}
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/*
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* For the purposes of write gathering, we must decide if the credential
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* associated with two pending requests have equivilent privileges. Since
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* NFS only uses a subset of the BSD ucred -- the effective uid and group
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* IDs -- we have a compare routine that checks only the relevant fields.
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*/
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static int
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nfsrv_samecred(struct ucred *cr1, struct ucred *cr2)
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{
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int i;
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if (cr1->cr_uid != cr2->cr_uid)
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return (0);
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if (cr1->cr_ngroups != cr2->cr_ngroups)
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return (0);
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for (i = 0; i < cr1->cr_ngroups; i++) {
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if (cr1->cr_groups[i] != cr2->cr_groups[i])
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return (0);
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}
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return (1);
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}
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/*
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* NFS write service with write gathering support. Called when
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* nfsrvw_procrastinate > 0.
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@ -1451,7 +1473,7 @@ nfsrv_writegather(struct nfsrv_descript **ndp, struct nfssvc_sock *slp,
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*/
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for(; nfsd && NFSW_CONTIG(owp, nfsd); nfsd = wp) {
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wp = LIST_NEXT(nfsd, nd_hash);
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if (NFSW_SAMECRED(owp, nfsd))
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if (nfsrv_samecred(&owp->nd_cr, &nfsd->nd_cr))
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nfsrvw_coalesce(owp, nfsd);
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}
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} else {
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