cache: replace kern___getcwd with vn_getcwd

The previous routine was resulting in extra data copies most notably in
linux_getcwd.

sys/compat/linux/linux_getcwd.c

@@ -42,7 +42,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/systm.h>
-#include <sys/syscallsubr.h>
+#include <sys/vnode.h>
 #include <sys/proc.h>
 #include <sys/malloc.h>
 
@@ -60,28 +60,25 @@ __FBSDID("$FreeBSD$");
  * Find pathname of process's current directory.
  */
 int
-linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
+linux_getcwd(struct thread *td, struct linux_getcwd_args *uap)
 {
-	char *path;
-	int error, lenused;
+	char *buf, *retbuf;
+	size_t buflen;
+	int error;
 
-	/*
-	 * Linux returns ERANGE instead of EINVAL.
-	 */
-	if (args->bufsize < 2)
+	buflen = uap->bufsize;
+	if (__predict_false(buflen < 2))
 		return (ERANGE);
+	if (buflen > LINUX_PATH_MAX)
+		buflen = LINUX_PATH_MAX;
 
-	path = malloc(LINUX_PATH_MAX, M_LINUX, M_WAITOK);
-
-	error = kern___getcwd(td, path, UIO_SYSSPACE, args->bufsize,
-	    LINUX_PATH_MAX);
+	buf = malloc(buflen, M_TEMP, M_WAITOK);
+	error = vn_getcwd(td, buf, &retbuf, &buflen);
 	if (error == 0) {
-		lenused = strlen(path) + 1;
-		error = copyout(path, args->buf, lenused);
+		error = copyout(retbuf, uap->buf, buflen);
 		if (error == 0)
-			td->td_retval[0] = lenused;
+			td->td_retval[0] = buflen;
 	}
-
-	free(path, M_LINUX);
+	free(buf, M_TEMP);
 	return (error);
 }

sys/kern/kern_sig.c

@@ -3608,6 +3608,7 @@ coredump(struct thread *td)
 	struct vnode *vp;
 	struct flock lf;
 	struct vattr vattr;
+	size_t fullpathsize;
 	int error, error1, locked;
 	char *name;			/* name of corefile */
 	void *rl_cookie;
@@ -3711,13 +3712,14 @@ coredump(struct thread *td)
 	 * if the path of the core is relative, add the current dir in front if it.
 	 */
 	if (name[0] != '/') {
-		fullpath = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
-		if (kern___getcwd(td, fullpath, UIO_SYSSPACE, MAXPATHLEN, MAXPATHLEN) != 0) {
-			free(fullpath, M_TEMP);
+		fullpathsize = MAXPATHLEN;
+		freepath = malloc(fullpathsize, M_TEMP, M_WAITOK);
+		if (vn_getcwd(td, freepath, &fullpath, &fullpathsize) != 0) {
+			free(freepath, M_TEMP);
 			goto out2;
 		}
 		devctl_safe_quote_sb(sb, fullpath);
-		free(fullpath, M_TEMP);
+		free(freepath, M_TEMP);
 		sbuf_putc(sb, '/');
 	}
 	devctl_safe_quote_sb(sb, name);

sys/kern/vfs_cache.c

@@ -364,7 +364,7 @@ STATNODE_COUNTER(numposhits, "Number of cache hits (positive)");
 STATNODE_COUNTER(numnegzaps,
     "Number of cache hits (negative) we do not want to cache");
 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)");
-/* These count for kern___getcwd(), too. */
+/* These count for vn_getcwd(), too. */
 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls");
 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
 STATNODE_COUNTER(numfullpathfail2,
@@ -2171,26 +2171,31 @@ vfs_cache_lookup(struct vop_lookup_args *ap)
 int
 sys___getcwd(struct thread *td, struct __getcwd_args *uap)
 {
+	char *buf, *retbuf;
+	size_t buflen;
+	int error;
 
-	return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen,
-	    MAXPATHLEN));
+	buflen = uap->buflen;
+	if (__predict_false(buflen < 2))
+		return (EINVAL);
+	if (buflen > MAXPATHLEN)
+		buflen = MAXPATHLEN;
+
+	buf = malloc(buflen, M_TEMP, M_WAITOK);
+	error = vn_getcwd(td, buf, &retbuf, &buflen);
+	if (error == 0)
+		error = copyout(retbuf, uap->buf, buflen);
+	free(buf, M_TEMP);
+	return (error);
 }
 
 int
-kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen,
-    size_t path_max)
+vn_getcwd(struct thread *td, char *buf, char **retbuf, size_t *buflen)
 {
-	char *bp, *tmpbuf;
 	struct filedesc *fdp;
 	struct vnode *cdir, *rdir;
 	int error;
 
-	if (__predict_false(buflen < 2))
-		return (EINVAL);
-	if (buflen > path_max)
-		buflen = path_max;
-
-	tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
 	fdp = td->td_proc->p_fd;
 	FILEDESC_SLOCK(fdp);
 	cdir = fdp->fd_cdir;
@@ -2198,21 +2203,14 @@ kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen,
 	rdir = fdp->fd_rdir;
 	vrefact(rdir);
 	FILEDESC_SUNLOCK(fdp);
-	error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, &buflen);
+	error = vn_fullpath1(td, cdir, rdir, buf, retbuf, buflen);
 	vrele(rdir);
 	vrele(cdir);
 
-	if (!error) {
-		if (bufseg == UIO_SYSSPACE)
-			bcopy(bp, buf, buflen);
-		else
-			error = copyout(bp, buf, buflen);
 #ifdef KTRACE
-	if (KTRPOINT(curthread, KTR_NAMEI))
-		ktrnamei(bp);
+	if (KTRPOINT(curthread, KTR_NAMEI) && error == 0)
+		ktrnamei(*retbuf);
 #endif
-	}
-	free(tmpbuf, M_TEMP);
 	return (error);
 }
 
@@ -2338,7 +2336,7 @@ vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, size_t *buflen)
 }
 
 /*
- * The magic behind kern___getcwd() and vn_fullpath().
+ * The magic behind vn_getcwd() and vn_fullpath().
  */
 static int
 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,

sys/sys/syscallsubr.h

@@ -65,8 +65,6 @@ struct uio;
 
 typedef int (*mmap_check_fp_fn)(struct file *, int, int, int);
 
-int	kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg,
-	    size_t buflen, size_t path_max);
 int	kern_accept(struct thread *td, int s, struct sockaddr **name,
 	    socklen_t *namelen, struct file **fp);
 int	kern_accept4(struct thread *td, int s, struct sockaddr **name,

sys/sys/vnode.h

@@ -632,6 +632,7 @@ u_quad_t init_va_filerev(void);
 int	speedup_syncer(void);
 int	vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf,
 	    size_t *buflen);
+int	vn_getcwd(struct thread *td, char *buf, char **retbuf, size_t *buflen);
 int	vn_fullpath(struct thread *td, struct vnode *vn,
 	    char **retbuf, char **freebuf);
 int	vn_fullpath_global(struct thread *td, struct vnode *vn,