Author: rmacklem
Date: Thu Feb  4 16:57:01 2010
New Revision: 203492
URL: http://svn.freebsd.org/changeset/base/203492

Log:
  MFC: r202767
  Add a timeout for the negative name cache entries in the NFS client.
  This avoids a bogus negative name cache entry from persisting forever
  when another client creates an entry with the same name within the
  same NFS server time of day clock tick. The mount option negnametimeo
  can be used to override the default timeout interval on a
  per-mount-point basis. Setting negnametimeo to 0 disables negative
  name caching for the mount point.
  I also fixed one obvious typo where args.timeo should be
  args.maxgrouplist.
  
  Submitted by: jhb (earlier version)
  Reviewed by:  jhb

Modified:
  stable/8/sys/nfsclient/nfs_vfsops.c
  stable/8/sys/nfsclient/nfs_vnops.c
  stable/8/sys/nfsclient/nfsmount.h
  stable/8/sys/nfsclient/nfsnode.h
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (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/xen/xenpci/   (props changed)

Modified: stable/8/sys/nfsclient/nfs_vfsops.c
==============================================================================
--- stable/8/sys/nfsclient/nfs_vfsops.c Thu Feb  4 15:26:16 2010        
(r203491)
+++ stable/8/sys/nfsclient/nfs_vfsops.c Thu Feb  4 16:57:01 2010        
(r203492)
@@ -114,7 +114,7 @@ static void nfs_decode_args(struct mount
                    struct nfs_args *argp, const char *hostname);
 static int     mountnfs(struct nfs_args *, struct mount *,
                    struct sockaddr *, char *, struct vnode **,
-                   struct ucred *cred);
+                   struct ucred *cred, int);
 static vfs_mount_t nfs_mount;
 static vfs_cmount_t nfs_cmount;
 static vfs_unmount_t nfs_unmount;
@@ -551,7 +551,7 @@ nfs_mountdiskless(char *path,
 
        nam = sodupsockaddr((struct sockaddr *)sin, M_WAITOK);
        if ((error = mountnfs(args, mp, nam, path, vpp,
-           td->td_ucred)) != 0) {
+           td->td_ucred, NFS_DEFAULT_NEGNAMETIMEO)) != 0) {
                printf("nfs_mountroot: mount %s on /: %d\n", path, error);
                return (error);
        }
@@ -778,7 +778,7 @@ static const char *nfs_opts[] = { "from"
     "readdirsize", "soft", "hard", "mntudp", "tcp", "udp", "wsize", "rsize",
     "retrans", "acregmin", "acregmax", "acdirmin", "acdirmax", 
     "deadthresh", "hostname", "timeout", "addr", "fh", "nfsv3", "sec",
-    "maxgroups", "principal",
+    "maxgroups", "principal", "negnametimeo",
     NULL };
 
 /*
@@ -827,6 +827,7 @@ nfs_mount(struct mount *mp)
        size_t len;
        u_char nfh[NFSX_V3FHMAX];
        char *opt;
+       int negnametimeo = NFS_DEFAULT_NEGNAMETIMEO;
 
        has_nfs_args_opt = 0;
        has_addr_opt = 0;
@@ -1029,7 +1030,7 @@ nfs_mount(struct mount *mp)
        }
        if (vfs_getopt(mp->mnt_optnew, "maxgroups", (void **)&opt, NULL) == 0) {
                ret = sscanf(opt, "%d", &args.maxgrouplist);
-               if (ret != 1 || args.timeo <= 0) {
+               if (ret != 1 || args.maxgrouplist <= 0) {
                        vfs_mount_error(mp, "illegal maxgroups: %s",
                            opt);
                        error = EINVAL;
@@ -1037,6 +1038,16 @@ nfs_mount(struct mount *mp)
                }
                args.flags |= NFSMNT_MAXGRPS;
        }
+       if (vfs_getopt(mp->mnt_optnew, "negnametimeo", (void **)&opt, NULL)
+           == 0) {
+               ret = sscanf(opt, "%d", &negnametimeo);
+               if (ret != 1 || negnametimeo < 0) {
+                       vfs_mount_error(mp, "illegal negnametimeo: %s",
+                           opt);
+                       error = EINVAL;
+                       goto out;
+               }
+       }
        if (vfs_getopt(mp->mnt_optnew, "addr", (void **)&args.addr,
                &args.addrlen) == 0) {
                has_addr_opt = 1;
@@ -1125,7 +1136,7 @@ nfs_mount(struct mount *mp)
                }
        }
        error = mountnfs(&args, mp, nam, args.hostname, &vp,
-           curthread->td_ucred);
+           curthread->td_ucred, negnametimeo);
 out:
        if (!error) {
                MNT_ILOCK(mp);
@@ -1167,7 +1178,7 @@ nfs_cmount(struct mntarg *ma, void *data
  */
 static int
 mountnfs(struct nfs_args *argp, struct mount *mp, struct sockaddr *nam,
-    char *hst, struct vnode **vpp, struct ucred *cred)
+    char *hst, struct vnode **vpp, struct ucred *cred, int negnametimeo)
 {
        struct nfsmount *nmp;
        struct nfsnode *np;
@@ -1217,6 +1228,7 @@ mountnfs(struct nfs_args *argp, struct m
        nmp->nm_numgrps = NFS_MAXGRPS;
        nmp->nm_readahead = NFS_DEFRAHEAD;
        nmp->nm_deadthresh = NFS_MAXDEADTHRESH;
+       nmp->nm_negnametimeo = negnametimeo;
        nmp->nm_tprintf_delay = nfs_tprintf_delay;
        if (nmp->nm_tprintf_delay < 0)
                nmp->nm_tprintf_delay = 0;

Modified: stable/8/sys/nfsclient/nfs_vnops.c
==============================================================================
--- stable/8/sys/nfsclient/nfs_vnops.c  Thu Feb  4 15:26:16 2010        
(r203491)
+++ stable/8/sys/nfsclient/nfs_vnops.c  Thu Feb  4 16:57:01 2010        
(r203492)
@@ -982,8 +982,13 @@ nfs_lookup(struct vop_lookup_args *ap)
                 * modification time of the parent directory matches
                 * our cached copy.  Otherwise, we discard all of the
                 * negative cache entries for this directory.
+                * negative cache entries for this directory. We also
+                * only trust -ve cache entries for less than
+                * nm_negative_namecache_timeout seconds.
                 */
-               if (VOP_GETATTR(dvp, &vattr, cnp->cn_cred) == 0 &&
+               if ((u_int)(ticks - np->n_dmtime_ticks) <
+                   (nmp->nm_negnametimeo * hz) &&
+                   VOP_GETATTR(dvp, &vattr, cnp->cn_cred) == 0 &&
                    vattr.va_mtime.tv_sec == np->n_dmtime) {
                        nfsstats.lookupcache_hits++;
                        return (ENOENT);
@@ -1157,8 +1162,10 @@ nfsmout:
                         */
                        mtx_lock(&np->n_mtx);
                        if (np->n_dmtime <= dmtime) {
-                               if (np->n_dmtime == 0)
+                               if (np->n_dmtime == 0) {
                                        np->n_dmtime = dmtime;
+                                       np->n_dmtime_ticks = ticks;
+                               }
                                mtx_unlock(&np->n_mtx);
                                cache_enter(dvp, NULL, cnp);
                        } else

Modified: stable/8/sys/nfsclient/nfsmount.h
==============================================================================
--- stable/8/sys/nfsclient/nfsmount.h   Thu Feb  4 15:26:16 2010        
(r203491)
+++ stable/8/sys/nfsclient/nfsmount.h   Thu Feb  4 16:57:01 2010        
(r203492)
@@ -85,6 +85,7 @@ struct        nfsmount {
        struct rpc_timers nm_timers[NFS_MAX_TIMER]; /* RTT Timers for rpcs */
        char    nm_principal[MNAMELEN]; /* GSS-API principal of server */
        gss_OID nm_mech_oid;            /* OID of selected GSS-API mechanism */
+       int     nm_negnametimeo;        /* timeout for -ve entries (sec) */
 
        /* NFSv4 */
        uint64_t nm_clientid;
@@ -107,6 +108,10 @@ struct     nfsmount {
 #define NFS_TPRINTF_DELAY               30
 #endif
 
+#ifndef NFS_DEFAULT_NEGNAMETIMEO
+#define NFS_DEFAULT_NEGNAMETIMEO       60
+#endif
+
 #define        NFS_PCATCH      (PCATCH | PBDRY)
 
 #endif

Modified: stable/8/sys/nfsclient/nfsnode.h
==============================================================================
--- stable/8/sys/nfsclient/nfsnode.h    Thu Feb  4 15:26:16 2010        
(r203491)
+++ stable/8/sys/nfsclient/nfsnode.h    Thu Feb  4 16:57:01 2010        
(r203492)
@@ -114,6 +114,7 @@ struct nfsnode {
        struct timespec         n_mtime;        /* Prev modify time. */
        time_t                  n_ctime;        /* Prev create time. */
        time_t                  n_dmtime;       /* Prev dir modify time. */
+       int                     n_dmtime_ticks; /* Tick of -ve cache entry */
        time_t                  n_expiry;       /* Lease expiry time */
        nfsfh_t                 *n_fhp;         /* NFS File Handle */
        struct vnode            *n_vnode;       /* associated vnode */
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