Date: Sun, 27 May 2012 14:20:47 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r236150 - in stable/8/sys: fs/nfsclient nfsclient Message-ID: <201205271420.q4REKl88054037@svn.freebsd.org>
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Author: rmacklem Date: Sun May 27 14:20:46 2012 New Revision: 236150 URL: http://svn.freebsd.org/changeset/base/236150 Log: MFC: r235332 PR# 165923 reported intermittent write failures for dirty memory mapped pages being written back on an NFS mount. Since any thread can call VOP_PUTPAGES() to write back a dirty page, the credentials of that thread may not have write access to the file on an NFS server. (Often the uid is 0, which may be mapped to "nobody" in the NFS server.) Although there is no completely correct fix for this (NFS servers check access on every write RPC instead of at open/mmap time), this patch avoids the common cases by holding onto a credential that recently opened the file for writing and uses that credential for the write RPCs being done by VOP_PUTPAGES() for both NFS clients. Modified: stable/8/sys/fs/nfsclient/nfs_clbio.c stable/8/sys/fs/nfsclient/nfs_clnode.c stable/8/sys/fs/nfsclient/nfs_clvnops.c stable/8/sys/fs/nfsclient/nfsnode.h stable/8/sys/nfsclient/nfs_bio.c stable/8/sys/nfsclient/nfs_node.c stable/8/sys/nfsclient/nfs_vnops.c stable/8/sys/nfsclient/nfsnode.h Directory Properties: stable/8/sys/ (props changed) stable/8/sys/amd64/include/xen/ (props changed) stable/8/sys/boot/ (props changed) stable/8/sys/cddl/contrib/opensolaris/ (props changed) stable/8/sys/contrib/dev/acpica/ (props changed) stable/8/sys/contrib/pf/ (props changed) stable/8/sys/dev/e1000/ (props changed) Modified: stable/8/sys/fs/nfsclient/nfs_clbio.c ============================================================================== --- stable/8/sys/fs/nfsclient/nfs_clbio.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/fs/nfsclient/nfs_clbio.c Sun May 27 14:20:46 2012 (r236150) @@ -271,7 +271,11 @@ ncl_putpages(struct vop_putpages_args *a vp = ap->a_vp; np = VTONFS(vp); td = curthread; /* XXX */ - cred = curthread->td_ucred; /* XXX */ + /* Set the cred to n_writecred for the write rpcs. */ + if (np->n_writecred != NULL) + cred = crhold(np->n_writecred); + else + cred = crhold(curthread->td_ucred); /* XXX */ nmp = VFSTONFS(vp->v_mount); pages = ap->a_m; count = ap->a_count; @@ -335,6 +339,7 @@ ncl_putpages(struct vop_putpages_args *a iomode = NFSWRITE_FILESYNC; error = ncl_writerpc(vp, &uio, cred, &iomode, &must_commit, 0); + crfree(cred); pmap_qremove(kva, npages); relpbuf(bp, &ncl_pbuf_freecnt); Modified: stable/8/sys/fs/nfsclient/nfs_clnode.c ============================================================================== --- stable/8/sys/fs/nfsclient/nfs_clnode.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/fs/nfsclient/nfs_clnode.c Sun May 27 14:20:46 2012 (r236150) @@ -297,6 +297,8 @@ ncl_reclaim(struct vop_reclaim_args *ap) FREE((caddr_t)dp2, M_NFSDIROFF); } } + if (np->n_writecred != NULL) + crfree(np->n_writecred); FREE((caddr_t)np->n_fhp, M_NFSFH); if (np->n_v4 != NULL) FREE((caddr_t)np->n_v4, M_NFSV4NODE); Modified: stable/8/sys/fs/nfsclient/nfs_clvnops.c ============================================================================== --- stable/8/sys/fs/nfsclient/nfs_clvnops.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/fs/nfsclient/nfs_clvnops.c Sun May 27 14:20:46 2012 (r236150) @@ -480,6 +480,7 @@ nfs_open(struct vop_open_args *ap) struct vattr vattr; int error; int fmode = ap->a_mode; + struct ucred *cred; if (vp->v_type != VREG && vp->v_type != VDIR && vp->v_type != VLNK) return (EOPNOTSUPP); @@ -570,7 +571,22 @@ nfs_open(struct vop_open_args *ap) } np->n_directio_opens++; } + + /* + * If this is an open for writing, capture a reference to the + * credentials, so they can be used by ncl_putpages(). Using + * these write credentials is preferable to the credentials of + * whatever thread happens to be doing the VOP_PUTPAGES() since + * the write RPCs are less likely to fail with EACCES. + */ + if ((fmode & FWRITE) != 0) { + cred = np->n_writecred; + np->n_writecred = crhold(ap->a_cred); + } else + cred = NULL; mtx_unlock(&np->n_mtx); + if (cred != NULL) + crfree(cred); vnode_create_vobject(vp, vattr.va_size, ap->a_td); return (0); } Modified: stable/8/sys/fs/nfsclient/nfsnode.h ============================================================================== --- stable/8/sys/fs/nfsclient/nfsnode.h Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/fs/nfsclient/nfsnode.h Sun May 27 14:20:46 2012 (r236150) @@ -136,6 +136,7 @@ struct nfsnode { struct nfsv4node *n_v4; /* extra V4 stuff */ struct timespec n_unused4; struct timespec n_unused5; + struct ucred *n_writecred; /* Cred. for putpages */ }; #define n_atim n_un1.nf_atim Modified: stable/8/sys/nfsclient/nfs_bio.c ============================================================================== --- stable/8/sys/nfsclient/nfs_bio.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/nfsclient/nfs_bio.c Sun May 27 14:20:46 2012 (r236150) @@ -268,7 +268,11 @@ nfs_putpages(struct vop_putpages_args *a vp = ap->a_vp; np = VTONFS(vp); td = curthread; /* XXX */ - cred = curthread->td_ucred; /* XXX */ + /* Set the cred to n_writecred for the write rpcs. */ + if (np->n_writecred != NULL) + cred = crhold(np->n_writecred); + else + cred = crhold(curthread->td_ucred); /* XXX */ nmp = VFSTONFS(vp->v_mount); pages = ap->a_m; count = ap->a_count; @@ -332,6 +336,7 @@ nfs_putpages(struct vop_putpages_args *a iomode = NFSV3WRITE_FILESYNC; error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit); + crfree(cred); pmap_qremove(kva, npages); relpbuf(bp, &nfs_pbuf_freecnt); Modified: stable/8/sys/nfsclient/nfs_node.c ============================================================================== --- stable/8/sys/nfsclient/nfs_node.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/nfsclient/nfs_node.c Sun May 27 14:20:46 2012 (r236150) @@ -270,6 +270,8 @@ nfs_reclaim(struct vop_reclaim_args *ap) free((caddr_t)dp2, M_NFSDIROFF); } } + if (np->n_writecred != NULL) + crfree(np->n_writecred); if (np->n_fhsize > NFS_SMALLFH) { free((caddr_t)np->n_fhp, M_NFSBIGFH); } Modified: stable/8/sys/nfsclient/nfs_vnops.c ============================================================================== --- stable/8/sys/nfsclient/nfs_vnops.c Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/nfsclient/nfs_vnops.c Sun May 27 14:20:46 2012 (r236150) @@ -510,6 +510,7 @@ nfs_open(struct vop_open_args *ap) struct vattr vattr; int error; int fmode = ap->a_mode; + struct ucred *cred; if (vp->v_type != VREG && vp->v_type != VDIR && vp->v_type != VLNK) return (EOPNOTSUPP); @@ -566,7 +567,22 @@ nfs_open(struct vop_open_args *ap) } np->n_directio_opens++; } + + /* + * If this is an open for writing, capture a reference to the + * credentials, so they can be used by nfs_putpages(). Using + * these write credentials is preferable to the credentials of + * whatever thread happens to be doing the VOP_PUTPAGES() since + * the write RPCs are less likely to fail with EACCES. + */ + if ((fmode & FWRITE) != 0) { + cred = np->n_writecred; + np->n_writecred = crhold(ap->a_cred); + } else + cred = NULL; mtx_unlock(&np->n_mtx); + if (cred != NULL) + crfree(cred); vnode_create_vobject(vp, vattr.va_size, ap->a_td); return (0); } Modified: stable/8/sys/nfsclient/nfsnode.h ============================================================================== --- stable/8/sys/nfsclient/nfsnode.h Sun May 27 13:33:54 2012 (r236149) +++ stable/8/sys/nfsclient/nfsnode.h Sun May 27 14:20:46 2012 (r236150) @@ -141,6 +141,7 @@ struct nfsnode { struct nfs_attrcache_timestamp n_unused; struct timespec n_unused4; struct timespec n_unused5; + struct ucred *n_writecred; /* Cred. for putpages */ }; #define n_atim n_un1.nf_atim
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