libspl: move kmem implementation from libzpool

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #17861

lib/libspl/Makefile.am

@@ -19,6 +19,7 @@ libspl_la_SOURCES = \
 	%D%/condvar.c \
 	%D%/cred.c \
 	%D%/getexecname.c \
+	%D%/kmem.c \
 	%D%/kstat.c \
 	%D%/list.c \
 	%D%/mkdirp.c \

lib/libspl/kmem.c

@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: CDDL-1.0
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or https://opensource.org/licenses/CDDL-1.0.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2016 Actifio, Inc. All rights reserved.
+ * Copyright (c) 2025, Klara, Inc.
+ */
+
+#include <sys/kmem.h>
+
+char *
+kmem_vasprintf(const char *fmt, va_list adx)
+{
+	char *buf = NULL;
+	va_list adx_copy;
+
+	va_copy(adx_copy, adx);
+	VERIFY(vasprintf(&buf, fmt, adx_copy) != -1);
+	va_end(adx_copy);
+
+	return (buf);
+}
+
+char *
+kmem_asprintf(const char *fmt, ...)
+{
+	char *buf = NULL;
+	va_list adx;
+
+	va_start(adx, fmt);
+	VERIFY(vasprintf(&buf, fmt, adx) != -1);
+	va_end(adx);
+
+	return (buf);
+}
+
+/*
+ * kmem_scnprintf() will return the number of characters that it would have
+ * printed whenever it is limited by value of the size variable, rather than
+ * the number of characters that it did print. This can cause misbehavior on
+ * subsequent uses of the return value, so we define a safe version that will
+ * return the number of characters actually printed, minus the NULL format
+ * character.  Subsequent use of this by the safe string functions is safe
+ * whether it is snprintf(), strlcat() or strlcpy().
+ */
+int
+kmem_scnprintf(char *restrict str, size_t size, const char *restrict fmt, ...)
+{
+	int n;
+	va_list ap;
+
+	/* Make the 0 case a no-op so that we do not return -1 */
+	if (size == 0)
+		return (0);
+
+	va_start(ap, fmt);
+	n = vsnprintf(str, size, fmt, ap);
+	va_end(ap);
+
+	if (n >= size)
+		n = size - 1;
+
+	return (n);
+}
+
+fstrans_cookie_t
+spl_fstrans_mark(void)
+{
+	return ((fstrans_cookie_t)0);
+}
+
+void
+spl_fstrans_unmark(fstrans_cookie_t cookie)
+{
+	(void) cookie;
+}
+
+int
+kmem_cache_reap_active(void)
+{
+	return (0);
+}

lib/libzpool/kernel.c

@@ -587,61 +587,6 @@ ksiddomain_rele(ksiddomain_t *ksid)
 	umem_free(ksid, sizeof (ksiddomain_t));
 }
 
-char *
-kmem_vasprintf(const char *fmt, va_list adx)
-{
-	char *buf = NULL;
-	va_list adx_copy;
-
-	va_copy(adx_copy, adx);
-	VERIFY(vasprintf(&buf, fmt, adx_copy) != -1);
-	va_end(adx_copy);
-
-	return (buf);
-}
-
-char *
-kmem_asprintf(const char *fmt, ...)
-{
-	char *buf = NULL;
-	va_list adx;
-
-	va_start(adx, fmt);
-	VERIFY(vasprintf(&buf, fmt, adx) != -1);
-	va_end(adx);
-
-	return (buf);
-}
-
-/*
- * kmem_scnprintf() will return the number of characters that it would have
- * printed whenever it is limited by value of the size variable, rather than
- * the number of characters that it did print. This can cause misbehavior on
- * subsequent uses of the return value, so we define a safe version that will
- * return the number of characters actually printed, minus the NULL format
- * character.  Subsequent use of this by the safe string functions is safe
- * whether it is snprintf(), strlcat() or strlcpy().
- */
-int
-kmem_scnprintf(char *restrict str, size_t size, const char *restrict fmt, ...)
-{
-	int n;
-	va_list ap;
-
-	/* Make the 0 case a no-op so that we do not return -1 */
-	if (size == 0)
-		return (0);
-
-	va_start(ap, fmt);
-	n = vsnprintf(str, size, fmt, ap);
-	va_end(ap);
-
-	if (n >= size)
-		n = size - 1;
-
-	return (n);
-}
-
 zfs_file_t *
 zfs_onexit_fd_hold(int fd, minor_t *minorp)
 {
@@ -664,24 +609,6 @@ zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
 	return (0);
 }
 
-fstrans_cookie_t
-spl_fstrans_mark(void)
-{
-	return ((fstrans_cookie_t)0);
-}
-
-void
-spl_fstrans_unmark(fstrans_cookie_t cookie)
-{
-	(void) cookie;
-}
-
-int
-kmem_cache_reap_active(void)
-{
-	return (0);
-}
-
 void
 zvol_create_minors(const char *name)
 {