assertion in arc_release() during encrypted receive

In the existing code, when doing a raw (encrypted) zfs receive, 
we call arc_convert_to_raw() from open context. This creates a 
race condition between arc_release()/arc_change_state() and 
writing out the block from syncing context (arc_write_ready/done()).

This change makes it so that when we are doing a raw (encrypted) 
zfs receive, we save the crypt parameters (salt, iv, mac) of dnode 
blocks in the dbuf_dirty_record_t, and call arc_convert_to_raw() 
from syncing context when writing out the block of dnodes.

Additionally, we can eliminate dr_raw and associated setters, and 
instead know that dnode blocks are always raw when doing a zfs 
receive (see the new field os_raw_receive).

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #7424 
Closes #7429

include/sys/dbuf.h

@@ -147,7 +147,16 @@ typedef struct dbuf_dirty_record {
 			override_states_t dr_override_state;
 			uint8_t dr_copies;
 			boolean_t dr_nopwrite;
-			boolean_t dr_raw;
+			boolean_t dr_has_raw_params;
+
+			/*
+			 * If dr_has_raw_params is set, the following crypt
+			 * params will be set on the BP that's written.
+			 */
+			boolean_t dr_byteorder;
+			uint8_t	dr_salt[ZIO_DATA_SALT_LEN];
+			uint8_t	dr_iv[ZIO_DATA_IV_LEN];
+			uint8_t	dr_mac[ZIO_DATA_MAC_LEN];
 		} dl;
 	} dt;
 } dbuf_dirty_record_t;

include/sys/dmu.h

@@ -472,7 +472,6 @@ void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
     dmu_tx_t *tx);
 
-int dmu_object_dirty_raw(objset_t *os, uint64_t object, dmu_tx_t *tx);
 
 int dmu_object_remap_indirects(objset_t *os, uint64_t object, uint64_t txg);
 
@@ -715,7 +714,8 @@ struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
  */
 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
-void dmu_buf_will_change_crypt_params(dmu_buf_t *db, dmu_tx_t *tx);
+void dmu_buf_set_crypt_params(dmu_buf_t *db_fake, boolean_t byteorder,
+    const uint8_t *salt, const uint8_t *iv, const uint8_t *mac, dmu_tx_t *tx);
 
 /*
  * You must create a transaction, then hold the objects which you will
@@ -794,10 +794,7 @@ int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
     uint64_t size, dmu_tx_t *tx);
 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
     uint64_t size);
-int dmu_free_long_range_raw(objset_t *os, uint64_t object, uint64_t offset,
-    uint64_t size);
 int dmu_free_long_object(objset_t *os, uint64_t object);
-int dmu_free_long_object_raw(objset_t *os, uint64_t object);
 
 /*
  * Convenience functions.
@@ -837,9 +834,6 @@ void dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset,
 void dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset,
     struct arc_buf *buf, dmu_tx_t *tx);
 #define	dmu_assign_arcbuf	dmu_assign_arcbuf_by_dbuf
-int dmu_convert_mdn_block_to_raw(objset_t *os, uint64_t firstobj,
-    boolean_t byteorder, const uint8_t *salt, const uint8_t *iv,
-    const uint8_t *mac, dmu_tx_t *tx);
 void dmu_copy_from_buf(objset_t *os, uint64_t object, uint64_t offset,
     dmu_buf_t *handle, dmu_tx_t *tx);
 #ifdef HAVE_UIO_ZEROCOPY

include/sys/dmu_objset.h

@@ -139,6 +139,7 @@ struct objset {
 	uint64_t os_flags;
 	uint64_t os_freed_dnodes;
 	boolean_t os_rescan_dnodes;
+	boolean_t os_raw_receive;
 
 	/* os_phys_buf should be written raw next txg */
 	boolean_t os_next_write_raw[TXG_SIZE];