Add SDT DTrace probes for namei():

  vfs:namei:lookup:entry takes parent directory vnode pointer, path to
    look up, and lookup flags.
  vfs:namei:lookup:return takes an error value, and if successful, the
    returned vnode pointer.

MFC after:      1 month

1 files changed, 14 insertions, 1 deletions

diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index 77c2e42..757e56e 100644
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -37,6 +37,7 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_kdtrace.h"
 #include "opt_ktrace.h"
 #include "opt_mac.h"
 
@@ -51,6 +52,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mount.h>
 #include <sys/filedesc.h>
 #include <sys/proc.h>
+#include <sys/sdt.h>
 #include <sys/syscallsubr.h>
 #include <sys/sysctl.h>
 #ifdef KTRACE
@@ -65,6 +67,11 @@ __FBSDID("$FreeBSD$");
 #define	NAMEI_DIAGNOSTIC 1
 #undef NAMEI_DIAGNOSTIC
 
+SDT_PROVIDER_DECLARE(vfs);
+SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *",
+    "unsigned long");
+SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *");
+
 /*
  * Allocation zone for namei
  */
@@ -181,7 +188,6 @@ namei(struct nameidata *ndp)
 		ktrnamei(cnp->cn_pnbuf);
 	}
 #endif
-
 	/*
 	 * Get starting point for the translation.
 	 */
@@ -224,6 +230,8 @@ namei(struct nameidata *ndp)
 			VFS_UNLOCK_GIANT(vfslocked);
 		}
 	}
+	SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf,
+	    cnp->cn_flags, 0, 0);
 	vfslocked = VFS_LOCK_GIANT(dp->v_mount);
 	for (;;) {
 		/*
@@ -252,6 +260,8 @@ namei(struct nameidata *ndp)
 			cnp->cn_pnbuf = NULL;
 			cnp->cn_nameptr = NULL;
 #endif
+			SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0,
+			    0, 0);
 			return (error);
 		}
 		vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
@@ -273,6 +283,8 @@ namei(struct nameidata *ndp)
 				VFS_UNLOCK_GIANT(vfslocked);
 			} else if (vfslocked)
 				ndp->ni_cnd.cn_flags |= GIANTHELD;
+			SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp,
+			    0, 0, 0);
 			return (0);
 		}
 		if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
@@ -338,6 +350,7 @@ namei(struct nameidata *ndp)
 	ndp->ni_vp = NULL;
 	vrele(ndp->ni_dvp);
 	VFS_UNLOCK_GIANT(vfslocked);
+	SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0);
 	return (error);
 }