Skip dnode handles use when not needed

include/sys/dbuf.h

@@ -214,9 +214,15 @@ typedef struct dmu_buf_impl {
 	struct objset *db_objset;
 
 	/*
-	 * handle to safely access the dnode we belong to (NULL when evicted)
+	 * Handle to safely access the dnode we belong to (NULL when evicted)
+	 * if dnode_move() is used on the platform, or just dnode otherwise.
 	 */
+#if !defined(__linux__) && !defined(__FreeBSD__)
+#define	USE_DNODE_HANDLE	1
 	struct dnode_handle *db_dnode_handle;
+#else
+	struct dnode *db_dnode;
+#endif
 
 	/*
 	 * our parent buffer; if the dnode points to us directly,
@@ -417,11 +423,19 @@ void dbuf_stats_destroy(void);
 int dbuf_dnode_findbp(dnode_t *dn, uint64_t level, uint64_t blkid,
     blkptr_t *bp, uint16_t *datablkszsec, uint8_t *indblkshift);
 
+#ifdef USE_DNODE_HANDLE
 #define	DB_DNODE(_db)		((_db)->db_dnode_handle->dnh_dnode)
 #define	DB_DNODE_LOCK(_db)	((_db)->db_dnode_handle->dnh_zrlock)
 #define	DB_DNODE_ENTER(_db)	(zrl_add(&DB_DNODE_LOCK(_db)))
 #define	DB_DNODE_EXIT(_db)	(zrl_remove(&DB_DNODE_LOCK(_db)))
 #define	DB_DNODE_HELD(_db)	(!zrl_is_zero(&DB_DNODE_LOCK(_db)))
+#else
+#define	DB_DNODE(_db)		((_db)->db_dnode)
+#define	DB_DNODE_LOCK(_db)
+#define	DB_DNODE_ENTER(_db)
+#define	DB_DNODE_EXIT(_db)
+#define	DB_DNODE_HELD(_db)	(B_TRUE)
+#endif
 
 void dbuf_init(void);
 void dbuf_fini(void);

module/zfs/dbuf.c

@@ -3103,7 +3103,11 @@ dbuf_destroy(dmu_buf_impl_t *db)
 		 */
 		mutex_enter(&dn->dn_mtx);
 		dnode_rele_and_unlock(dn, db, B_TRUE);
+#ifdef USE_DNODE_HANDLE
 		db->db_dnode_handle = NULL;
+#else
+		db->db_dnode = NULL;
+#endif
 
 		dbuf_hash_remove(db);
 	} else {
@@ -3252,7 +3256,11 @@ dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
 	db->db_level = level;
 	db->db_blkid = blkid;
 	db->db_dirtycnt = 0;
+#ifdef USE_DNODE_HANDLE
 	db->db_dnode_handle = dn->dn_handle;
+#else
+	db->db_dnode = dn;
+#endif
 	db->db_parent = parent;
 	db->db_blkptr = blkptr;
 	db->db_hash = hash;
@@ -4390,7 +4398,7 @@ dbuf_lightweight_bp(dbuf_dirty_record_t *dr)
 		dmu_buf_impl_t *parent_db = dr->dr_parent->dr_dbuf;
 		int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
 		VERIFY3U(parent_db->db_level, ==, 1);
-		VERIFY3P(parent_db->db_dnode_handle->dnh_dnode, ==, dn);
+		VERIFY3P(DB_DNODE(parent_db), ==, dn);
 		VERIFY3U(dr->dt.dll.dr_blkid >> epbs, ==, parent_db->db_blkid);
 		blkptr_t *bp = parent_db->db.db_data;
 		return (&bp[dr->dt.dll.dr_blkid & ((1 << epbs) - 1)]);
@@ -4813,14 +4821,13 @@ dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
 {
 	(void) zio, (void) buf;
 	dmu_buf_impl_t *db = vdb;
-	dnode_t *dn;
 	blkptr_t *bp;
 	unsigned int epbs, i;
 
 	ASSERT3U(db->db_level, >, 0);
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
+	epbs = DB_DNODE(db)->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
+	DB_DNODE_EXIT(db);
 	ASSERT3U(epbs, <, 31);
 
 	/* Determine if all our children are holes */
@@ -4843,7 +4850,6 @@ dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
 		memset(db->db.db_data, 0, db->db.db_size);
 		rw_exit(&db->db_rwlock);
 	}
-	DB_DNODE_EXIT(db);
 }
 
 static void
@@ -5062,8 +5068,7 @@ dbuf_remap(dnode_t *dn, dmu_buf_impl_t *db, dmu_tx_t *tx)
 		}
 	} else if (db->db.db_object == DMU_META_DNODE_OBJECT) {
 		dnode_phys_t *dnp = db->db.db_data;
-		ASSERT3U(db->db_dnode_handle->dnh_dnode->dn_type, ==,
-		    DMU_OT_DNODE);
+		ASSERT3U(dn->dn_type, ==, DMU_OT_DNODE);
 		for (int i = 0; i < db->db.db_size >> DNODE_SHIFT;
 		    i += dnp[i].dn_extra_slots + 1) {
 			for (int j = 0; j < dnp[i].dn_nblkptr; j++) {

module/zfs/dmu.c

@@ -276,13 +276,14 @@ dmu_set_bonus(dmu_buf_t *db_fake, int newsize, dmu_tx_t *tx)
 	dnode_t *dn;
 	int error;
 
+	if (newsize < 0 || newsize > db_fake->db_size)
+		return (SET_ERROR(EINVAL));
+
 	DB_DNODE_ENTER(db);
 	dn = DB_DNODE(db);
 
 	if (dn->dn_bonus != db) {
 		error = SET_ERROR(EINVAL);
-	} else if (newsize < 0 || newsize > db_fake->db_size) {
-		error = SET_ERROR(EINVAL);
 	} else {
 		dnode_setbonuslen(dn, newsize, tx);
 		error = 0;
@@ -299,12 +300,13 @@ dmu_set_bonustype(dmu_buf_t *db_fake, dmu_object_type_t type, dmu_tx_t *tx)
 	dnode_t *dn;
 	int error;
 
+	if (!DMU_OT_IS_VALID(type))
+		return (SET_ERROR(EINVAL));
+
 	DB_DNODE_ENTER(db);
 	dn = DB_DNODE(db);
 
-	if (!DMU_OT_IS_VALID(type)) {
-		error = SET_ERROR(EINVAL);
-	} else if (dn->dn_bonus != db) {
+	if (dn->dn_bonus != db) {
 		error = SET_ERROR(EINVAL);
 	} else {
 		dnode_setbonus_type(dn, type, tx);
@@ -319,12 +321,10 @@ dmu_object_type_t
 dmu_get_bonustype(dmu_buf_t *db_fake)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
-	dnode_t *dn;
 	dmu_object_type_t type;
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	type = dn->dn_bonustype;
+	type = DB_DNODE(db)->dn_bonustype;
 	DB_DNODE_EXIT(db);
 
 	return (type);
@@ -486,16 +486,14 @@ dmu_spill_hold_by_bonus(dmu_buf_t *bonus, uint32_t flags, const void *tag,
     dmu_buf_t **dbp)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
-	dnode_t *dn;
 	int err;
 	uint32_t db_flags = DB_RF_CANFAIL;
 
 	if (flags & DMU_READ_NO_DECRYPT)
 		db_flags |= DB_RF_NO_DECRYPT;
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	err = dmu_spill_hold_by_dnode(dn, db_flags, tag, dbp);
+	err = dmu_spill_hold_by_dnode(DB_DNODE(db), db_flags, tag, dbp);
 	DB_DNODE_EXIT(db);
 
 	return (err);
@@ -668,13 +666,11 @@ dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
     dmu_buf_t ***dbpp)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
-	dnode_t *dn;
 	int err;
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
-	    numbufsp, dbpp, DMU_READ_PREFETCH);
+	err = dmu_buf_hold_array_by_dnode(DB_DNODE(db), offset, length, read,
+	    tag, numbufsp, dbpp, DMU_READ_PREFETCH);
 	DB_DNODE_EXIT(db);
 
 	return (err);
@@ -1301,15 +1297,13 @@ int
 dmu_read_uio_dbuf(dmu_buf_t *zdb, zfs_uio_t *uio, uint64_t size)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
-	dnode_t *dn;
 	int err;
 
 	if (size == 0)
 		return (0);
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	err = dmu_read_uio_dnode(dn, uio, size);
+	err = dmu_read_uio_dnode(DB_DNODE(db), uio, size);
 	DB_DNODE_EXIT(db);
 
 	return (err);
@@ -1403,15 +1397,13 @@ dmu_write_uio_dbuf(dmu_buf_t *zdb, zfs_uio_t *uio, uint64_t size,
     dmu_tx_t *tx)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
-	dnode_t *dn;
 	int err;
 
 	if (size == 0)
 		return (0);
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	err = dmu_write_uio_dnode(dn, uio, size, tx);
+	err = dmu_write_uio_dnode(DB_DNODE(db), uio, size, tx);
 	DB_DNODE_EXIT(db);
 
 	return (err);
@@ -1539,11 +1531,11 @@ dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
     dmu_tx_t *tx)
 {
 	int err;
-	dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
+	dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
 
-	DB_DNODE_ENTER(dbuf);
-	err = dmu_assign_arcbuf_by_dnode(DB_DNODE(dbuf), offset, buf, tx);
-	DB_DNODE_EXIT(dbuf);
+	DB_DNODE_ENTER(db);
+	err = dmu_assign_arcbuf_by_dnode(DB_DNODE(db), offset, buf, tx);
+	DB_DNODE_EXIT(db);
 
 	return (err);
 }
@@ -1782,7 +1774,6 @@ dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
 	dmu_sync_arg_t *dsa;
 	zbookmark_phys_t zb;
 	zio_prop_t zp;
-	dnode_t *dn;
 
 	ASSERT(pio != NULL);
 	ASSERT(txg != 0);
@@ -1791,8 +1782,7 @@ dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
 	    db->db.db_object, db->db_level, db->db_blkid);
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
+	dmu_write_policy(os, DB_DNODE(db), db->db_level, WP_DMU_SYNC, &zp);
 	DB_DNODE_EXIT(db);
 
 	/*
@@ -1877,11 +1867,14 @@ dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
 	 * zio_done(), which VERIFYs that the override BP is identical
 	 * to the on-disk BP.
 	 */
-	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	if (dr_next != NULL || dnode_block_freed(dn, db->db_blkid))
+	if (dr_next != NULL) {
 		zp.zp_nopwrite = B_FALSE;
-	DB_DNODE_EXIT(db);
+	} else {
+		DB_DNODE_ENTER(db);
+		if (dnode_block_freed(DB_DNODE(db), db->db_blkid))
+			zp.zp_nopwrite = B_FALSE;
+		DB_DNODE_EXIT(db);
+	}
 
 	ASSERT(dr->dr_txg == txg);
 	if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
@@ -2487,11 +2480,9 @@ void
 dmu_object_dnsize_from_db(dmu_buf_t *db_fake, int *dnsize)
 {
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
-	dnode_t *dn;
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	*dnsize = dn->dn_num_slots << DNODE_SHIFT;
+	*dnsize = DB_DNODE(db)->dn_num_slots << DNODE_SHIFT;
 	DB_DNODE_EXIT(db);
 }
 

module/zfs/dmu_tx.c

@@ -1520,11 +1520,8 @@ dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *hdl, boolean_t may_grow)
 		ASSERT(tx->tx_txg == 0);
 		dmu_tx_hold_spill(tx, object);
 	} else {
-		dnode_t *dn;
-
 		DB_DNODE_ENTER(db);
-		dn = DB_DNODE(db);
-		if (dn->dn_have_spill) {
+		if (DB_DNODE(db)->dn_have_spill) {
 			ASSERT(tx->tx_txg == 0);
 			dmu_tx_hold_spill(tx, object);
 		}

module/zfs/dnode.c

@@ -1020,6 +1020,19 @@ dnode_move(void *buf, void *newbuf, size_t size, void *arg)
 	int64_t refcount;
 	uint32_t dbufs;
 
+#ifndef USE_DNODE_HANDLE
+	/*
+	 * We can't move dnodes if dbufs reference them directly without
+	 * using handles and respecitve locking.  Unless USE_DNODE_HANDLE
+	 * is defined the code below is only to make sure it still builds,
+	 * but it should never be used, since it is unsafe.
+	 */
+#ifdef ZFS_DEBUG
+	PANIC("dnode_move() called without USE_DNODE_HANDLE");
+#endif
+	return (KMEM_CBRC_NO);
+#endif
+
 	/*
 	 * The dnode is on the objset's list of known dnodes if the objset
 	 * pointer is valid. We set the low bit of the objset pointer when
@@ -1757,7 +1770,7 @@ dnode_rele_and_unlock(dnode_t *dn, const void *tag, boolean_t evicting)
 	 * handle.
 	 */
 #ifdef ZFS_DEBUG
-	ASSERT(refs > 0 || dnh->dnh_zrlock.zr_owner != curthread);
+	ASSERT(refs > 0 || zrl_owner(&dnh->dnh_zrlock) != curthread);
 #endif
 
 	/* NOTE: the DNODE_DNODE does not have a dn_dbuf */

module/zfs/sa.c

@@ -1852,7 +1852,6 @@ sa_modify_attrs(sa_handle_t *hdl, sa_attr_type_t newattr,
 {
 	sa_os_t *sa = hdl->sa_os->os_sa;
 	dmu_buf_impl_t *db = (dmu_buf_impl_t *)hdl->sa_bonus;
-	dnode_t *dn;
 	sa_bulk_attr_t *attr_desc;
 	void *old_data[2];
 	int bonus_attr_count = 0;
@@ -1872,8 +1871,7 @@ sa_modify_attrs(sa_handle_t *hdl, sa_attr_type_t newattr,
 	/* First make of copy of the old data */
 
 	DB_DNODE_ENTER(db);
-	dn = DB_DNODE(db);
-	if (dn->dn_bonuslen != 0) {
+	if (DB_DNODE(db)->dn_bonuslen != 0) {
 		bonus_data_size = hdl->sa_bonus->db_size;
 		old_data[0] = kmem_alloc(bonus_data_size, KM_SLEEP);
 		memcpy(old_data[0], hdl->sa_bonus->db_data,

module/zfs/zfs_log.c

@@ -665,13 +665,13 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 			DB_DNODE_ENTER(db);
 			err = dmu_read_by_dnode(DB_DNODE(db), off, len, lr + 1,
 			    DMU_READ_NO_PREFETCH);
+			DB_DNODE_EXIT(db);
 			if (err != 0) {
 				zil_itx_destroy(itx);
 				itx = zil_itx_create(txtype, sizeof (*lr));
 				lr = (lr_write_t *)&itx->itx_lr;
 				wr_state = WR_NEED_COPY;
 			}
-			DB_DNODE_EXIT(db);
 		}
 
 		itx->itx_wr_state = wr_state;