Author: rwatson
Date: Tue Apr 7 20:58:56 2009
New Revision: 190829
URL: http://svn.freebsd.org/changeset/base/190829
Log:
Nul-terminate strings in the VFS name cache, which negligibly change
the size and cost of name cache entries, but make adding debugging
and tracing easier.
Add SDT DTrace probes for various namecache events:
vfs:namecache:enter:done - new entry in the name cache, passed parent
directory vnode pointer, name added to the cache, and child vnode
pointer.
vfs:namecache:enter_negative:done - new negative entry in the name cache,
passed parent vnode pointer, name added to the cache.
vfs:namecache:fullpath:enter - call to vn_fullpath1() is made, passed
the vnode to resolve to a name.
vfs:namecache:fullpath:hit - vn_fullpath1() successfully resolved a
search for the parent of an object using the namecache, passed the
discovered parent directory vnode pointer, name, and child vnode
pointer.
vfs:namecache:fullpath:miss - vn_fullpath1() failed to resolve a search
for the parent of an object using the namecache, passed the child
vnode pointer.
vfs:namecache:fullpath:return - vn_fullpath1() has completed, passed the
error number, and if that is zero, the vnode to resolve, and the
returned path.
vfs:namecache:lookup:hit - postive name cache entry hit, passed the
parent directory vnode pointer, name, and child vnode pointer.
vfs:namecache:lookup:hit_negative - negative name cache entry hit,
passed the parent directory vnode pointer and name.
vfs:namecache:lookup:miss - name cache miss, passed the parent directory
pointer and the full remaining component name (not terminated after the
cache miss component).
vfs:namecache:purge:done - name cache purge for a vnode, passed the vnode
pointer to purge.
vfs:namecache:purge_negative:done - name cache purge of negative entries
for children of a vnode, passed the vnode pointer to purge.
vfs:namecache:purgevfs - name cache purge for a mountpoint, passed the
mount pointer. Separate probes will also be invoked for each cache
entry zapped.
vfs:namecache:zap:done - name cache entry zapped, passed the parent
directory vnode pointer, name, and child vnode pointer.
vfs:namecache:zap_negative:done - negative name cache entry zapped,
passed the parent directory vnode pointer and name.
For any probes involving an extant name cache entry (enter, hit, zapp),
we use the nul-terminated string for the name component. For misses,
the remainder of the path, including later components, is provided as
an argument instead since there is no handy nul-terminated version of
the string around. This is arguably a bug.
MFC after: 1 month
Sponsored by: Google, Inc.
Reviewed by: jhb, kan, kib (earlier version)
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Tue Apr 7 20:34:34 2009 (r190828)
+++ head/sys/kern/vfs_cache.c Tue Apr 7 20:58:56 2009 (r190829)
@@ -35,6 +35,7 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
+#include "opt_kdtrace.h"
#include "opt_ktrace.h"
#include <sys/param.h>
@@ -47,6 +48,7 @@ __FBSDID("$FreeBSD$");
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
+#include <sys/sdt.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
@@ -58,6 +60,31 @@ __FBSDID("$FreeBSD$");
#include <vm/uma.h>
+SDT_PROVIDER_DECLARE(vfs);
+SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
+ "struct vnode *");
+SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
+ "char *");
+SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
+SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
+ "struct char *", "struct vnode *");
+SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
+SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", "struct vnode *",
+ "struct char *");
+SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
+ "struct vnode *");
+SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, "struct vnode *",
+ "char *");
+SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
+ "char *");
+SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
+SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
+SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
+SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
+ "struct vnode *");
+SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *",
+ "char *");
+
/*
* This structure describes the elements in the cache of recent
* names looked up by namei.
@@ -71,7 +98,7 @@ struct namecache {
struct vnode *nc_vp; /* vnode the name refers to */
u_char nc_flag; /* flag bits */
u_char nc_nlen; /* length of name */
- char nc_name[0]; /* segment name */
+ char nc_name[0]; /* segment name + nul */
};
/*
@@ -133,9 +160,10 @@ RW_SYSINIT(vfscache, &cache_lock, "Name
static uma_zone_t cache_zone_small;
static uma_zone_t cache_zone_large;
-#define CACHE_PATH_CUTOFF 32
-#define CACHE_ZONE_SMALL (sizeof(struct namecache) +
CACHE_PATH_CUTOFF)
-#define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX)
+#define CACHE_PATH_CUTOFF 35
+#define CACHE_ZONE_SMALL (sizeof(struct namecache) +
CACHE_PATH_CUTOFF \
+ + 1)
+#define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX +
1)
#define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \
cache_zone_small : cache_zone_large, M_WAITOK)
@@ -291,6 +319,15 @@ cache_zap(ncp)
rw_assert(&cache_lock, RA_WLOCKED);
CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
+#ifdef KDTRACE_HOOKS
+ if (ncp->nc_vp != NULL) {
+ SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp,
+ ncp->nc_name, ncp->nc_vp, 0, 0);
+ } else {
+ SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp,
+ ncp->nc_name, 0, 0, 0);
+ }
+#endif
vp = NULL;
LIST_REMOVE(ncp, nc_hash);
if (ncp->nc_flag & NCF_ISDOTDOT) {
@@ -361,12 +398,17 @@ retry_wlocked:
CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
dvp, cnp->cn_nameptr);
dothits++;
+ SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".",
+ *vpp, 0, 0);
goto success;
}
if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
dotdothits++;
- if (dvp->v_cache_dd == NULL)
+ if (dvp->v_cache_dd == NULL) {
+ SDT_PROBE(vfs, namecache, lookup, miss, dvp,
+ "..", NULL, 0, 0);
goto unlock;
+ }
if ((cnp->cn_flags & MAKEENTRY) == 0) {
if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT)
cache_zap(dvp->v_cache_dd);
@@ -379,6 +421,8 @@ retry_wlocked:
*vpp = dvp->v_cache_dd->nc_dvp;
CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
dvp, cnp->cn_nameptr, *vpp);
+ SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..",
+ *vpp, 0, 0);
goto success;
}
}
@@ -394,6 +438,8 @@ retry_wlocked:
/* We failed to find an entry */
if (ncp == NULL) {
+ SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
+ NULL, 0, 0);
if ((cnp->cn_flags & MAKEENTRY) == 0) {
nummisszap++;
} else {
@@ -421,6 +467,8 @@ retry_wlocked:
*vpp = ncp->nc_vp;
CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
dvp, cnp->cn_nameptr, *vpp, ncp);
+ SDT_PROBE(vfs, namecache, lookup, hit, dvp, ncp->nc_name,
+ *vpp, 0, 0);
goto success;
}
@@ -449,6 +497,8 @@ retry_wlocked:
nchstats.ncs_neghits++;
if (ncp->nc_flag & NCF_WHITE)
cnp->cn_flags |= ISWHITEOUT;
+ SDT_PROBE(vfs, namecache, lookup, hit_negative, dvp, ncp->nc_name,
+ 0, 0, 0);
CACHE_WUNLOCK();
return (ENOENT);
@@ -579,6 +629,8 @@ cache_enter(dvp, vp, cnp)
}
}
dvp->v_cache_dd = NULL;
+ SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp,
+ 0, 0);
CACHE_WUNLOCK();
flag = NCF_ISDOTDOT;
}
@@ -597,7 +649,7 @@ cache_enter(dvp, vp, cnp)
ncp->nc_flag = flag;
len = ncp->nc_nlen = cnp->cn_namelen;
hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
- bcopy(cnp->cn_nameptr, ncp->nc_name, len);
+ strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1);
hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
CACHE_WLOCK();
@@ -667,8 +719,12 @@ cache_enter(dvp, vp, cnp)
*/
if (vp) {
TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
+ SDT_PROBE(vfs, namecache, enter, done, dvp, ncp->nc_name, vp,
+ 0, 0);
} else {
TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
+ SDT_PROBE(vfs, namecache, enter_negative, done, dvp,
+ ncp->nc_name, 0, 0, 0);
}
if (numneg * ncnegfactor > numcache) {
ncp = TAILQ_FIRST(&ncneg);
@@ -709,6 +765,7 @@ cache_purge(vp)
{
CTR1(KTR_VFS, "cache_purge(%p)", vp);
+ SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0);
CACHE_WLOCK();
while (!LIST_EMPTY(&vp->v_cache_src))
cache_zap(LIST_FIRST(&vp->v_cache_src));
@@ -733,6 +790,7 @@ cache_purge_negative(vp)
struct namecache *cp, *ncp;
CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
+ SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0);
CACHE_WLOCK();
LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) {
if (cp->nc_vp == NULL)
@@ -752,6 +810,7 @@ cache_purgevfs(mp)
struct namecache *ncp, *nnp;
/* Scan hash tables for applicable entries */
+ SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0);
CACHE_WLOCK();
for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
@@ -998,6 +1057,9 @@ vn_fullpath1(struct thread *td, struct v
char *bp;
int error, i, slash_prefixed;
struct namecache *ncp;
+#ifdef KDTRACE_HOOKS
+ struct vnode *startvp = vp;
+#endif
buflen--;
bp = buf + buflen;
@@ -1005,6 +1067,7 @@ vn_fullpath1(struct thread *td, struct v
error = 0;
slash_prefixed = 0;
+ SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0);
CACHE_RLOCK();
numfullpathcalls++;
if (vp->v_type != VDIR) {
@@ -1016,18 +1079,31 @@ vn_fullpath1(struct thread *td, struct v
if (bp == buf) {
numfullpathfail4++;
CACHE_RUNLOCK();
- return (ENOMEM);
+ error = ENOMEM;
+ SDT_PROBE(vfs, namecache, fullpath, return,
+ error, startvp, NULL, 0, 0);
+ return (error);
}
+ SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
+ ncp->nc_name, vp, 0, 0);
vp = ncp->nc_dvp;
} else {
+ SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0,
+ 0, 0);
error = vn_vptocnp(&vp, &bp, buf, &buflen);
- if (error)
+ if (error) {
+ SDT_PROBE(vfs, namecache, fullpath, return,
+ error, startvp, NULL, 0, 0);
return (error);
+ }
}
if (buflen <= 0) {
numfullpathfail4++;
CACHE_RUNLOCK();
- return (ENOMEM);
+ error = ENOMEM;
+ SDT_PROBE(vfs, namecache, fullpath, return, error,
+ startvp, NULL, 0, 0);
+ return (error);
}
*--bp = '/';
buflen--;
@@ -1062,8 +1138,12 @@ vn_fullpath1(struct thread *td, struct v
error = ENOMEM;
break;
}
+ SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
+ ncp->nc_name, vp, 0, 0);
vp = ncp->nc_dvp;
} else {
+ SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0,
+ 0, 0);
error = vn_vptocnp(&vp, &bp, buf, &buflen);
if (error)
break;
@@ -1078,12 +1158,17 @@ vn_fullpath1(struct thread *td, struct v
buflen--;
slash_prefixed = 1;
}
- if (error)
+ if (error) {
+ SDT_PROBE(vfs, namecache, fullpath, return, error, startvp,
+ NULL, 0, 0);
return (error);
+ }
if (!slash_prefixed) {
if (bp == buf) {
numfullpathfail4++;
CACHE_RUNLOCK();
+ SDT_PROBE(vfs, namecache, fullpath, return, 0,
+ startvp, bp, 0, 0);
return (ENOMEM);
} else
*--bp = '/';
@@ -1091,6 +1176,7 @@ vn_fullpath1(struct thread *td, struct v
numfullpathfound++;
CACHE_RUNLOCK();
+ SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, bp, 0, 0);
*retbuf = bp;
return (0);
}
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
