zfs_debug: specific variant for userspace

Just nice and simple, with room to grow.

Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16492

lib/libzpool/Makefile.am

@@ -17,7 +17,8 @@ dist_libzpool_la_SOURCES = \
 	%D%/taskq.c \
 	%D%/util.c \
 	%D%/vdev_label_os.c \
-	%D%/zfs_racct.c
+	%D%/zfs_racct.c \
+	%D%/zfs_debug.c
 
 nodist_libzpool_la_SOURCES = \
 	module/lua/lapi.c \
@@ -46,7 +47,6 @@ nodist_libzpool_la_SOURCES = \
 	module/lua/lzio.c \
 	\
 	module/os/linux/zfs/vdev_file.c \
-	module/os/linux/zfs/zfs_debug.c \
 	module/os/linux/zfs/zio_crypt.c \
 	\
 	module/zcommon/cityhash.c \

lib/libzpool/vdev_label_os.c

@@ -30,10 +30,16 @@
 #include <sys/vdev_impl.h>
 
 /*
- * Check if the reserved boot area is in-use.
+ * Check if the reserved boot area is in-use. This is called from
+ * spa_vdev_attach() when adding a device to a raidz vdev, to ensure that the
+ * reserved area is available as scratch space for raidz expansion.
  *
- * This function always returns 0, as there are no known external uses
- * of the reserved area on Linux.
+ * This function currently always returns 0. On Linux, there are no known
+ * external uses of the reserved area. On FreeBSD, the reserved boot area is
+ * used when booting to a ZFS root from an MBR partition.
+ *
+ * Currently nothing using libzpool can add a disk to a pool, so this does
+ * nothing.
  */
 int
 vdev_check_boot_reserve(spa_t *spa, vdev_t *childvd)

lib/libzpool/zfs_debug.c

@@ -0,0 +1,106 @@
+/*
+ * 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) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
+ */
+
+#include <sys/zfs_context.h>
+
+typedef struct zfs_dbgmsg {
+	list_node_t		zdm_node;
+	uint64_t		zdm_timestamp;
+	uint_t			zdm_size;
+	char			zdm_msg[]; /* variable length allocation */
+} zfs_dbgmsg_t;
+
+static list_t zfs_dbgmsgs;
+static kmutex_t zfs_dbgmsgs_lock;
+
+int zfs_dbgmsg_enable = B_TRUE;
+
+void
+zfs_dbgmsg_init(void)
+{
+	list_create(&zfs_dbgmsgs, sizeof (zfs_dbgmsg_t),
+	    offsetof(zfs_dbgmsg_t, zdm_node));
+	mutex_init(&zfs_dbgmsgs_lock, NULL, MUTEX_DEFAULT, NULL);
+}
+
+void
+zfs_dbgmsg_fini(void)
+{
+	zfs_dbgmsg_t *zdm;
+	while ((zdm = list_remove_head(&zfs_dbgmsgs)))
+		umem_free(zdm, zdm->zdm_size);
+	mutex_destroy(&zfs_dbgmsgs_lock);
+}
+
+void
+__set_error(const char *file, const char *func, int line, int err)
+{
+	if (zfs_flags & ZFS_DEBUG_SET_ERROR)
+		__dprintf(B_FALSE, file, func, line, "error %lu",
+		    (ulong_t)err);
+}
+
+void
+__zfs_dbgmsg(char *buf)
+{
+	uint_t size = sizeof (zfs_dbgmsg_t) + strlen(buf) + 1;
+	zfs_dbgmsg_t *zdm = umem_zalloc(size, KM_SLEEP);
+	zdm->zdm_size = size;
+	zdm->zdm_timestamp = gethrestime_sec();
+	strcpy(zdm->zdm_msg, buf);
+
+	mutex_enter(&zfs_dbgmsgs_lock);
+	list_insert_tail(&zfs_dbgmsgs, zdm);
+	mutex_exit(&zfs_dbgmsgs_lock);
+}
+
+void
+zfs_dbgmsg_print(int fd, const char *tag)
+{
+	ssize_t ret __attribute__((unused));
+
+	mutex_enter(&zfs_dbgmsgs_lock);
+
+	/*
+	 * We use write() in this function instead of printf()
+	 * so it is safe to call from a signal handler.
+	 */
+	ret = write(fd, "ZFS_DBGMSG(", 11);
+	ret = write(fd, tag, strlen(tag));
+	ret = write(fd, ") START:\n", 9);
+
+	for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs); zdm != NULL;
+	    zdm = list_next(&zfs_dbgmsgs, zdm)) {
+		ret = write(fd, zdm->zdm_msg, strlen(zdm->zdm_msg));
+		ret = write(fd, "\n", 1);
+	}
+
+	ret = write(fd, "ZFS_DBGMSG(", 11);
+	ret = write(fd, tag, strlen(tag));
+	ret = write(fd, ") END\n", 6);
+
+	mutex_exit(&zfs_dbgmsgs_lock);
+}

module/os/freebsd/zfs/zfs_debug.c

@@ -140,15 +140,11 @@ zfs_dbgmsg_fini(void)
 {
 	if (zfs_dbgmsg_kstat)
 		kstat_delete(zfs_dbgmsg_kstat);
-	/*
-	 * TODO - decide how to make this permanent
-	 */
-#ifdef _KERNEL
+
 	mutex_enter(&zfs_dbgmsgs_lock);
 	zfs_dbgmsg_purge(0);
 	mutex_exit(&zfs_dbgmsgs_lock);
 	mutex_destroy(&zfs_dbgmsgs_lock);
-#endif
 }
 
 void
@@ -184,7 +180,6 @@ __set_error(const char *file, const char *func, int line, int err)
 		__dprintf(B_FALSE, file, func, line, "error %lu", (ulong_t)err);
 }
 
-#ifdef _KERNEL
 void
 __dprintf(boolean_t dprint, const char *file, const char *func,
     int line, const char *fmt, ...)
@@ -236,37 +231,6 @@ __dprintf(boolean_t dprint, const char *file, const char *func,
 	kmem_free(buf, size);
 }
 
-#else
-
-void
-zfs_dbgmsg_print(int fd, const char *tag)
-{
-	ssize_t ret __attribute__((unused));
-
-	/*
-	 * We use write() in this function instead of printf()
-	 * so it is safe to call from a signal handler.
-	 */
-	ret = write(fd, "ZFS_DBGMSG(", 11);
-	ret = write(fd, tag, strlen(tag));
-	ret = write(fd, ") START:\n", 9);
-
-	mutex_enter(&zfs_dbgmsgs_lock);
-
-	for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs); zdm != NULL;
-	    zdm = list_next(&zfs_dbgmsgs, zdm))
-		ret = write(fd, zdm->zdm_msg, strlen(zdm->zdm_msg));
-		ret = write(fd, "\n", 1);
-	}
-
-	ret = write(fd, "ZFS_DBGMSG(", 11);
-	ret = write(fd, tag, strlen(tag));
-	ret = write(fd, ") END\n", 6);
-
-	mutex_exit(&zfs_dbgmsgs_lock);
-}
-#endif /* _KERNEL */
-
 ZFS_MODULE_PARAM(zfs, zfs_, dbgmsg_enable, INT, ZMOD_RW,
 	"Enable ZFS debug message log");
 

module/os/linux/zfs/zfs_debug.c

@@ -111,12 +111,7 @@ zfs_dbgmsg_fini(void)
 	procfs_list_uninstall(&zfs_dbgmsgs);
 	zfs_dbgmsg_purge(0);
 
-	/*
-	 * TODO - decide how to make this permanent
-	 */
-#ifdef _KERNEL
 	procfs_list_destroy(&zfs_dbgmsgs);
-#endif
 }
 
 void
@@ -148,8 +143,6 @@ __zfs_dbgmsg(char *buf)
 	mutex_exit(&zfs_dbgmsgs.pl_lock);
 }
 
-#ifdef _KERNEL
-
 void
 __dprintf(boolean_t dprint, const char *file, const char *func,
     int line, const char *fmt, ...)
@@ -218,38 +211,6 @@ __dprintf(boolean_t dprint, const char *file, const char *func,
 	kmem_free(buf, size);
 }
 
-#else
-
-void
-zfs_dbgmsg_print(int fd, const char *tag)
-{
-	ssize_t ret __attribute__((unused));
-
-	mutex_enter(&zfs_dbgmsgs.pl_lock);
-
-	/*
-	 * We use write() in this function instead of printf()
-	 * so it is safe to call from a signal handler.
-	 */
-	ret = write(fd, "ZFS_DBGMSG(", 11);
-	ret = write(fd, tag, strlen(tag));
-	ret = write(fd, ") START:\n", 9);
-
-	for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
-	    zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
-		ret = write(fd, zdm->zdm_msg, strlen(zdm->zdm_msg));
-		ret = write(fd, "\n", 1);
-	}
-
-	ret = write(fd, "ZFS_DBGMSG(", 11);
-	ret = write(fd, tag, strlen(tag));
-	ret = write(fd, ") END\n", 6);
-
-	mutex_exit(&zfs_dbgmsgs.pl_lock);
-}
-#endif /* _KERNEL */
-
-#ifdef _KERNEL
 module_param(zfs_dbgmsg_enable, int, 0644);
 MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 
@@ -257,4 +218,3 @@ MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 module_param(zfs_dbgmsg_maxsize, uint, 0644);
 /* END CSTYLED */
 MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
-#endif