Reimplement the NFS ACCESS RPC cache as an "accelerator" rather than a true

cache.  If the cached result lets us say "yes", then go with that.  If
we're not sure, or we think the answer might be "no", go to the wire to be
certain.    This avoids all of the possible false veto cases, and allows us
to key the cached value with just the UID for which the cached value holds,
reducing the bloat of the nfsnode structure from 104 bytes to just 12 bytes.

Since the "yes" case is by far the most common, this should still provide
a substantial performance improvement.  Also default the cache to on, with
a conservative timeout (2 seconds).  This improves performance if NFS is
loaded as a KLD module, as there's not (yet) code to parse an option out
of the module arguments to set it, and sysctl doesn't work (yet) for OIDs
in modules.

The 'accelerator' mode was suggested by Bjoern Groenvall (bg@sics.se)

Feedback on this would be appreciated as testing has been necessarily
limited by Comdex, and it would be valuable to have this in 2.2.8.
This commit is contained in:
Mike Smith 1998-11-15 20:36:18 +00:00
parent cda43ef612
commit ad6d02135b
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=41186
4 changed files with 28 additions and 88 deletions

View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* @(#)nfs_vnops.c 8.16 (Berkeley) 5/27/95
* $Id: nfs_vnops.c,v 1.112 1998/11/13 02:39:09 msmith Exp $
* $Id: nfs_vnops.c,v 1.113 1998/11/13 22:58:48 msmith Exp $
*/
@ -248,7 +248,7 @@ struct nfsmount *nfs_iodmount[NFS_MAXASYNCDAEMON];
int nfs_numasync = 0;
#define DIRHDSIZ (sizeof (struct dirent) - (MAXNAMLEN + 1))
static int nfsaccess_cache_timeout;
static int nfsaccess_cache_timeout = 2;
SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW,
&nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout");
@ -260,23 +260,6 @@ static int nfsaccess_cache_fills;
SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_fills, CTLFLAG_RD,
&nfsaccess_cache_fills, 0, "NFS ACCESS cache fill count");
/*
* Compare two ucred structures, returns zero on equality, nonzero
* otherwise.
*/
static int
nfsa_ucredcmp(struct ucred *c1, struct ucred *c2)
{
int i;
if ((c1->cr_uid != c2->cr_uid) || (c1->cr_ngroups != c2->cr_ngroups))
return(1);
for (i = 0; i < c1->cr_ngroups; i++)
if (c1->cr_groups[i] != c2->cr_groups[i])
return(1);
return(0);
}
/*
* nfs access vnode op.
* For nfs version 2, just return ok. File accesses may fail later.
@ -352,13 +335,18 @@ nfs_access(ap)
wmode = mode;
}
/* do we have a cached result? */
/*
* Does our cached result allow us to give a definite yes to
* this request?
*/
if ((time_second < (np->n_modestamp + nfsaccess_cache_timeout)) &&
!nfsa_ucredcmp(ap->a_cred, &np->n_modecred)) {
(ap->a_cred->cr_uid == np->n_modeuid) &&
((np->n_mode & mode) == mode)) {
nfsaccess_cache_hits++;
if ((np->n_mode & mode) != mode)
error = EACCES;
} else {
/*
* Either a no, or a don't know. Go to the wire.
*/
nfsstats.rpccnt[NFSPROC_ACCESS]++;
nfsm_reqhead(vp, NFSPROC_ACCESS, NFSX_FH(v3) + NFSX_UNSIGNED);
nfsm_fhtom(vp, v3);
@ -380,7 +368,7 @@ nfs_access(ap)
/* cache the result */
nfsaccess_cache_fills++;
np->n_mode = rmode;
np->n_modecred = *ap->a_cred;
np->n_modeuid = ap->a_cred->cr_uid;
np->n_modestamp = time_second;
}
}
@ -700,11 +688,6 @@ nfs_setattr(ap)
ap->a_p, 1)) == EINTR)
return (error);
error = nfs_setattrrpc(vp, vap, ap->a_cred, ap->a_p);
/*
* Attributes on server may have changed, make no assumptions about
* the server's reaction to these changes.
*/
np->n_modestamp = 0;
if (error && vap->va_size != VNOVAL) {
np->n_size = np->n_vattr.va_size = tsize;
vnode_pager_setsize(vp, np->n_size);
@ -1562,7 +1545,6 @@ nfs_remove(ap)
error = nfs_sillyrename(dvp, vp, cnp);
zfree(namei_zone, cnp->cn_pnbuf);
np->n_attrstamp = 0;
np->n_modestamp = 0;
return (error);
}
@ -1667,18 +1649,6 @@ nfs_rename(ap)
cache_purge(fdvp);
}
/*
* We can't presume too much on the server's access control method(s),
* and it may use rules based on filenames or locations. Moving to a
* more restrictive location would be harmless, but moving to a less
* restrictive location you would be forced to wait for the cache
* entry to time out.
*/
if (fvp->v_data)
VTONFS(fvp)->n_modestamp = 0;
if (tvp != NULL)
VTONFS(tvp)->n_modestamp = 0;
out:
if (tdvp == tvp)
vrele(tdvp);

View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* @(#)nfsnode.h 8.9 (Berkeley) 5/14/95
* $Id: nfsnode.h,v 1.26 1998/05/31 18:32:23 peter Exp $
* $Id: nfsnode.h,v 1.27 1998/11/13 02:39:09 msmith Exp $
*/
@ -94,7 +94,7 @@ struct nfsnode {
struct vattr n_vattr; /* Vnode attribute cache */
time_t n_attrstamp; /* Attr. cache timestamp */
u_int32_t n_mode; /* ACCESS mode cache */
struct ucred n_modecred; /* credentials having mode */
uid_t n_modeuid; /* credentials having mode */
time_t n_modestamp; /* mode cache timestamp */
time_t n_mtime; /* Prev modify time. */
time_t n_ctime; /* Prev create time. */

View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* @(#)nfs_vnops.c 8.16 (Berkeley) 5/27/95
* $Id: nfs_vnops.c,v 1.112 1998/11/13 02:39:09 msmith Exp $
* $Id: nfs_vnops.c,v 1.113 1998/11/13 22:58:48 msmith Exp $
*/
@ -248,7 +248,7 @@ struct nfsmount *nfs_iodmount[NFS_MAXASYNCDAEMON];
int nfs_numasync = 0;
#define DIRHDSIZ (sizeof (struct dirent) - (MAXNAMLEN + 1))
static int nfsaccess_cache_timeout;
static int nfsaccess_cache_timeout = 2;
SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW,
&nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout");
@ -260,23 +260,6 @@ static int nfsaccess_cache_fills;
SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_fills, CTLFLAG_RD,
&nfsaccess_cache_fills, 0, "NFS ACCESS cache fill count");
/*
* Compare two ucred structures, returns zero on equality, nonzero
* otherwise.
*/
static int
nfsa_ucredcmp(struct ucred *c1, struct ucred *c2)
{
int i;
if ((c1->cr_uid != c2->cr_uid) || (c1->cr_ngroups != c2->cr_ngroups))
return(1);
for (i = 0; i < c1->cr_ngroups; i++)
if (c1->cr_groups[i] != c2->cr_groups[i])
return(1);
return(0);
}
/*
* nfs access vnode op.
* For nfs version 2, just return ok. File accesses may fail later.
@ -352,13 +335,18 @@ nfs_access(ap)
wmode = mode;
}
/* do we have a cached result? */
/*
* Does our cached result allow us to give a definite yes to
* this request?
*/
if ((time_second < (np->n_modestamp + nfsaccess_cache_timeout)) &&
!nfsa_ucredcmp(ap->a_cred, &np->n_modecred)) {
(ap->a_cred->cr_uid == np->n_modeuid) &&
((np->n_mode & mode) == mode)) {
nfsaccess_cache_hits++;
if ((np->n_mode & mode) != mode)
error = EACCES;
} else {
/*
* Either a no, or a don't know. Go to the wire.
*/
nfsstats.rpccnt[NFSPROC_ACCESS]++;
nfsm_reqhead(vp, NFSPROC_ACCESS, NFSX_FH(v3) + NFSX_UNSIGNED);
nfsm_fhtom(vp, v3);
@ -380,7 +368,7 @@ nfs_access(ap)
/* cache the result */
nfsaccess_cache_fills++;
np->n_mode = rmode;
np->n_modecred = *ap->a_cred;
np->n_modeuid = ap->a_cred->cr_uid;
np->n_modestamp = time_second;
}
}
@ -700,11 +688,6 @@ nfs_setattr(ap)
ap->a_p, 1)) == EINTR)
return (error);
error = nfs_setattrrpc(vp, vap, ap->a_cred, ap->a_p);
/*
* Attributes on server may have changed, make no assumptions about
* the server's reaction to these changes.
*/
np->n_modestamp = 0;
if (error && vap->va_size != VNOVAL) {
np->n_size = np->n_vattr.va_size = tsize;
vnode_pager_setsize(vp, np->n_size);
@ -1562,7 +1545,6 @@ nfs_remove(ap)
error = nfs_sillyrename(dvp, vp, cnp);
zfree(namei_zone, cnp->cn_pnbuf);
np->n_attrstamp = 0;
np->n_modestamp = 0;
return (error);
}
@ -1667,18 +1649,6 @@ nfs_rename(ap)
cache_purge(fdvp);
}
/*
* We can't presume too much on the server's access control method(s),
* and it may use rules based on filenames or locations. Moving to a
* more restrictive location would be harmless, but moving to a less
* restrictive location you would be forced to wait for the cache
* entry to time out.
*/
if (fvp->v_data)
VTONFS(fvp)->n_modestamp = 0;
if (tvp != NULL)
VTONFS(tvp)->n_modestamp = 0;
out:
if (tdvp == tvp)
vrele(tdvp);

View File

@ -34,7 +34,7 @@
* SUCH DAMAGE.
*
* @(#)nfsnode.h 8.9 (Berkeley) 5/14/95
* $Id: nfsnode.h,v 1.26 1998/05/31 18:32:23 peter Exp $
* $Id: nfsnode.h,v 1.27 1998/11/13 02:39:09 msmith Exp $
*/
@ -94,7 +94,7 @@ struct nfsnode {
struct vattr n_vattr; /* Vnode attribute cache */
time_t n_attrstamp; /* Attr. cache timestamp */
u_int32_t n_mode; /* ACCESS mode cache */
struct ucred n_modecred; /* credentials having mode */
uid_t n_modeuid; /* credentials having mode */
time_t n_modestamp; /* mode cache timestamp */
time_t n_mtime; /* Prev modify time. */
time_t n_ctime; /* Prev create time. */