OpenZFS 9236 - nuke spa_dbgmsg

We should use zfs_dbgmsg instead of spa_dbgmsg. Or at least,
metaslab_condense() should call zfs_dbgmsg because it's important and
rare enough to always log. It's possible that the message in
zio_dva_allocate() would be too high-frequency for zfs_dbgmsg.

Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

Patch Notes:
* Removed ZFS_DEBUG_SPA from zfs-module-parameters.5

OpenZFS-issue: https://www.illumos.org/issues/9236
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/cfaba7f668
Closes #7467

cmd/ztest/ztest.c

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
@@ -6660,7 +6660,6 @@ ztest_run(ztest_shared_t *zs)
 	 */
 	kernel_init(FREAD | FWRITE);
 	VERIFY0(spa_open(ztest_opts.zo_pool, &spa, FTAG));
-	spa->spa_debug = B_TRUE;
 	metaslab_preload_limit = ztest_random(20) + 1;
 	ztest_spa = spa;
 
@@ -6813,7 +6812,6 @@ ztest_freeze(void)
 	kernel_init(FREAD | FWRITE);
 	VERIFY3U(0, ==, spa_open(ztest_opts.zo_pool, &spa, FTAG));
 	VERIFY3U(0, ==, ztest_dataset_open(0));
-	spa->spa_debug = B_TRUE;
 	ztest_spa = spa;
 
 	/*
@@ -6882,7 +6880,6 @@ ztest_freeze(void)
 	VERIFY3U(0, ==, spa_open(ztest_opts.zo_pool, &spa, FTAG));
 	ASSERT(spa_freeze_txg(spa) == UINT64_MAX);
 	VERIFY3U(0, ==, ztest_dataset_open(0));
-	spa->spa_debug = B_TRUE;
 	ztest_spa = spa;
 	txg_wait_synced(spa_get_dsl(spa), 0);
 	ztest_dataset_close(0);

include/sys/spa.h

@@ -1094,13 +1094,6 @@ _NOTE(CONSTCOND) } while (0)
 #define	dprintf_bp(bp, fmt, ...)
 #endif
 
-extern boolean_t spa_debug_enabled(spa_t *spa);
-#define	spa_dbgmsg(spa, ...)			\
-{						\
-	if (spa_debug_enabled(spa))		\
-		zfs_dbgmsg(__VA_ARGS__);	\
-}
-
 extern int spa_mode_global;			/* mode, e.g. FREAD | FWRITE */
 extern int zfs_deadman_enabled;
 extern unsigned long zfs_deadman_synctime_ms;

include/sys/spa_impl.h

@@ -306,7 +306,6 @@ struct spa {
 	kcondvar_t	spa_suspend_cv;		/* notification of resume */
 	zio_suspend_reason_t	spa_suspended;	/* pool is suspended */
 	uint8_t		spa_claiming;		/* pool is doing zil_claim() */
-	boolean_t	spa_debug;		/* debug enabled? */
 	boolean_t	spa_is_root;		/* pool is root */
 	int		spa_minref;		/* num refs when first opened */
 	int		spa_mode;		/* FREAD | FWRITE */

include/sys/zfs_debug.h

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_ZFS_DEBUG_H
@@ -48,7 +48,7 @@ extern int zfs_dbgmsg_enable;
 #define	ZFS_DEBUG_DNODE_VERIFY		(1 << 2)
 #define	ZFS_DEBUG_SNAPNAMES		(1 << 3)
 #define	ZFS_DEBUG_MODIFY		(1 << 4)
-#define	ZFS_DEBUG_SPA			(1 << 5)
+/* 1<<5 was previously used, try not to reuse */
 #define	ZFS_DEBUG_ZIO_FREE		(1 << 6)
 #define	ZFS_DEBUG_HISTOGRAM_VERIFY	(1 << 7)
 #define	ZFS_DEBUG_METASLAB_VERIFY	(1 << 8)

man/man5/zfs-module-parameters.5

@@ -1387,9 +1387,6 @@ _
 16	ZFS_DEBUG_MODIFY
 	Check for illegally modified ARC buffers.
 _
-32	ZFS_DEBUG_SPA
-	Enable spa_dbgmsg entries in the debug log.
-_
 64	ZFS_DEBUG_ZIO_FREE
 	Enable verification of block frees.
 _

module/zfs/metaslab.c

@@ -1555,7 +1555,7 @@ metaslab_set_fragmentation(metaslab_t *msp)
 		if (spa_writeable(spa) && txg < spa_final_dirty_txg(spa)) {
 			msp->ms_condense_wanted = B_TRUE;
 			vdev_dirty(vd, VDD_METASLAB, msp, txg + 1);
-			spa_dbgmsg(spa, "txg %llu, requesting force condense: "
+			zfs_dbgmsg("txg %llu, requesting force condense: "
 			    "ms_id %llu, vdev_id %llu", txg, msp->ms_id,
 			    vd->vdev_id);
 		}
@@ -2081,7 +2081,7 @@ metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx)
 	ASSERT(msp->ms_loaded);
 
 
-	spa_dbgmsg(spa, "condensing: txg %llu, msp[%llu] %p, vdev id %llu, "
+	zfs_dbgmsg("condensing: txg %llu, msp[%llu] %p, vdev id %llu, "
 	    "spa %s, smp size %llu, segments %lu, forcing condense=%s", txg,
 	    msp->ms_id, msp, msp->ms_group->mg_vd->vdev_id,
 	    msp->ms_group->mg_vd->vdev_spa->spa_name,

module/zfs/spa_misc.c

@@ -248,7 +248,7 @@ int spa_mode_global;
  * by default in debug builds.
  */
 int zfs_flags = ~(ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SET_ERROR |
-    ZFS_DEBUG_SPA | ZFS_DEBUG_INDIRECT_REMAP);
+    ZFS_DEBUG_INDIRECT_REMAP);
 #else
 int zfs_flags = 0;
 #endif
@@ -659,8 +659,6 @@ spa_add(const char *name, nvlist_t *config, const char *altroot)
 		    KM_SLEEP) == 0);
 	}
 
-	spa->spa_debug = ((zfs_flags & ZFS_DEBUG_SPA) != 0);
-
 	spa->spa_min_ashift = INT_MAX;
 	spa->spa_max_ashift = 0;
 
@@ -2122,12 +2120,6 @@ spa_scan_get_stats(spa_t *spa, pool_scan_stat_t *ps)
 	return (0);
 }
 
-boolean_t
-spa_debug_enabled(spa_t *spa)
-{
-	return (spa->spa_debug);
-}
-
 int
 spa_maxblocksize(spa_t *spa)
 {

module/zfs/zio.c

@@ -3295,7 +3295,7 @@ zio_dva_allocate(zio_t *zio)
 	    &zio->io_alloc_list, zio);
 
 	if (error != 0) {
-		spa_dbgmsg(spa, "%s: metaslab allocation failure: zio %p, "
+		zfs_dbgmsg("%s: metaslab allocation failure: zio %p, "
 		    "size %llu, error %d", spa_name(spa), zio, zio->io_size,
 		    error);
 		if (error == ENOSPC && zio->io_size > SPA_MINBLOCKSIZE)