Cleanup ZFS debug infrastructure

Historically the internal zfs debug infrastructure has been
scattered throughout the code.  Since we expect to start making
more use of this code this patch performs some cleanup.

* Consolidate the zfs debug infrastructure in the zfs_debug.[ch]
  files.  This includes moving the zfs_flags and zfs_recover
  variables, plus moving the zfs_panic_recover() function.

* Remove the existing unused functionality in zfs_debug.c and
  replace it with code which correctly utilized the spl logging
  infrastructure.

* Remove the __dprintf() function from zfs_ioctl.c.  This is
  dead code, the dprintf() functionality in the kernel relies
  on the spl log support.

* Remove dprintf() from hdr_recl().  This wasn't particularly
  useful and was missing the required format specifier anyway.

* Subsequent patches should unify the dprintf() and zfs_dbgmsg()
  functions.

Signed-off-by: Brian Behlendorf <[email protected]>

4 files changed, 42 insertions, 119 deletions

diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 95d14a9e7..2220c4d9d 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -885,7 +885,6 @@ buf_dest(void *vbuf, void *unused)
 static void
 hdr_recl(void *unused)
 {
-	dprintf("hdr_recl called\n");
 	/*
 	 * umem calls the reclaim func when we destroy the buf cache,
 	 * which is after we do arc_fini().
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index e4e0c35f0..1016ac7be 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -234,21 +234,6 @@ static avl_tree_t spa_l2cache_avl;
 kmem_cache_t *spa_buffer_pool;
 int spa_mode_global;
 
-#ifdef ZFS_DEBUG
-/* Everything except dprintf is on by default in debug builds */
-int zfs_flags = ~ZFS_DEBUG_DPRINTF;
-#else
-int zfs_flags = 0;
-#endif
-
-/*
- * zfs_recover can be set to nonzero to attempt to recover from
- * otherwise-fatal errors, typically caused by on-disk corruption.  When
- * set, calls to zfs_panic_recover() will turn into warning messages.
- */
-int zfs_recover = 0;
-
-
 /*
  * ==========================================================================
  * SPA config locking
@@ -1217,16 +1202,6 @@ spa_freeze(spa_t *spa)
 		txg_wait_synced(spa_get_dsl(spa), freeze_txg);
 }
 
-void
-zfs_panic_recover(const char *fmt, ...)
-{
-	va_list adx;
-
-	va_start(adx, fmt);
-	vcmn_err(zfs_recover ? CE_WARN : CE_PANIC, fmt, adx);
-	va_end(adx);
-}
-
 /*
  * This is a stripped-down version of strtoull, suitable only for converting
  * lowercase hexidecimal numbers that don't overflow.
@@ -1765,7 +1740,4 @@ EXPORT_SYMBOL(spa_writeable);
 EXPORT_SYMBOL(spa_mode);
 
 EXPORT_SYMBOL(spa_namespace_lock);
-
-module_param(zfs_recover, int, 0644);
-MODULE_PARM_DESC(zfs_recover, "Set to attempt to recover from fatal errors");
 #endif
diff --git a/module/zfs/zfs_debug.c b/module/zfs/zfs_debug.c
index d0f411a99..f4b5e6fa1 100644
--- a/module/zfs/zfs_debug.c
+++ b/module/zfs/zfs_debug.c
@@ -24,72 +24,60 @@
 
 #include <sys/zfs_context.h>
 
-list_t zfs_dbgmsgs;
-int zfs_dbgmsg_size;
-kmutex_t zfs_dbgmsgs_lock;
-int zfs_dbgmsg_maxsize = 1<<20; /* 1MB */
+/*
+ * Enable various debugging features.
+ */
+int zfs_flags = 0;
+
+/*
+ * zfs_recover can be set to nonzero to attempt to recover from
+ * otherwise-fatal errors, typically caused by on-disk corruption.  When
+ * set, calls to zfs_panic_recover() will turn into warning messages.
+ */
+int zfs_recover = 0;
 
-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_panic_recover(const char *fmt, ...)
 {
-	zfs_dbgmsg_t *zdm;
+	va_list adx;
 
-	while ((zdm = list_remove_head(&zfs_dbgmsgs)) != NULL) {
-		int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
-		kmem_free(zdm, size);
-		zfs_dbgmsg_size -= size;
-	}
-	mutex_destroy(&zfs_dbgmsgs_lock);
-	ASSERT3U(zfs_dbgmsg_size, ==, 0);
+	va_start(adx, fmt);
+	vcmn_err(zfs_recover ? CE_WARN : CE_PANIC, fmt, adx);
+	va_end(adx);
 }
 
 /*
- * Print these messages by running:
- * 	echo ::zfs_dbgmsg | mdb -k
- *
- * Monitor these messages by running:
- * 	dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
+ * Debug logging is enabled by default for production kernel builds.
+ * The overhead for this is negligible and the logs can be valuable when
+ * debugging.  For non-production user space builds all debugging except
+ * logging is enabled since performance is no longer a concern.
  */
 void
-zfs_dbgmsg(const char *fmt, ...)
+zfs_dbgmsg_init(void)
 {
-	int size;
-	va_list adx;
-	zfs_dbgmsg_t *zdm;
-
-	va_start(adx, fmt);
-	size = vsnprintf(NULL, 0, fmt, adx);
-	va_end(adx);
+	if (zfs_flags == 0) {
+#if defined(_KERNEL)
+		zfs_flags = ZFS_DEBUG_DPRINTF;
+		spl_debug_mask |= SD_DPRINTF;
+		spl_debug_subsys |= SS_USER1;
+#else
+		zfs_flags = ~ZFS_DEBUG_DPRINTF;
+#endif /* _KERNEL */
+	}
+}
 
-	/*
-	 * There is one byte of string in sizeof (zfs_dbgmsg_t), used
-	 * for the terminating null.
-	 */
-	zdm = kmem_alloc(sizeof (zfs_dbgmsg_t) + size, KM_SLEEP);
-	zdm->zdm_timestamp = gethrestime_sec();
+void
+zfs_dbgmsg_fini(void)
+{
+	return;
+}
 
-	va_start(adx, fmt);
-	(void) vsnprintf(zdm->zdm_msg, size + 1, fmt, adx);
-	va_end(adx);
 
-	DTRACE_PROBE1(zfs__dbgmsg, char *, zdm->zdm_msg);
+#if defined(_KERNEL)
+module_param(zfs_flags, int, 0644);
+MODULE_PARM_DESC(zfs_flags, "Set additional debugging flags");
 
-	mutex_enter(&zfs_dbgmsgs_lock);
-	list_insert_tail(&zfs_dbgmsgs, zdm);
-	zfs_dbgmsg_size += sizeof (zfs_dbgmsg_t) + size;
-	while (zfs_dbgmsg_size > zfs_dbgmsg_maxsize) {
-		zdm = list_remove_head(&zfs_dbgmsgs);
-		size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
-		kmem_free(zdm, size);
-		zfs_dbgmsg_size -= size;
-	}
-	mutex_exit(&zfs_dbgmsgs_lock);
-}
+module_param(zfs_recover, int, 0644);
+MODULE_PARM_DESC(zfs_recover, "Set to attempt to recover from fatal errors");
+#endif /* _KERNEL */
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index c8ff03595..532f17aa1 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -119,42 +119,6 @@ static int zfs_fill_zplprops_root(uint64_t, nvlist_t *, nvlist_t *,
     boolean_t *);
 int zfs_set_prop_nvlist(const char *, zprop_source_t, nvlist_t *, nvlist_t **);
 
-/* _NOTE(PRINTFLIKE(4)) - this is printf-like, but lint is too whiney */
-void
-__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
-{
-	const char *newfile;
-	char buf[512];
-	va_list adx;
-
-	/*
-	 * Get rid of annoying "../common/" prefix to filename.
-	 */
-	newfile = strrchr(file, '/');
-	if (newfile != NULL) {
-		newfile = newfile + 1; /* Get rid of leading / */
-	} else {
-		newfile = file;
-	}
-
-	va_start(adx, fmt);
-	(void) vsnprintf(buf, sizeof (buf), fmt, adx);
-	va_end(adx);
-
-	/*
-	 * To get this data, use the zfs-dprintf probe as so:
-	 * dtrace -q -n 'zfs-dprintf \
-	 *	/stringof(arg0) == "dbuf.c"/ \
-	 *	{printf("%s: %s", stringof(arg1), stringof(arg3))}'
-	 * arg0 = file name
-	 * arg1 = function name
-	 * arg2 = line number
-	 * arg3 = message
-	 */
-	DTRACE_PROBE4(zfs__dprintf,
-	    char *, newfile, char *, func, int, line, char *, buf);
-}
-
 static void
 history_str_free(char *buf)
 {