zfs recv hangs if max recordsize is less than received recordsize

- Some optimizations for bqueue enqueue/dequeue.
- Added a fix to prevent deadlock when both bqueue_enqueue_impl()
and bqueue_dequeue() waits for signal to be triggered.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes #13855

include/sys/bqueue.h

@@ -30,22 +30,22 @@ typedef struct bqueue {
 	kmutex_t bq_lock;
 	kcondvar_t bq_add_cv;
 	kcondvar_t bq_pop_cv;
-	uint64_t bq_size;
-	uint64_t bq_maxsize;
-	uint64_t bq_fill_fraction;
+	size_t bq_size;
+	size_t bq_maxsize;
+	uint_t bq_fill_fraction;
 	size_t bq_node_offset;
 } bqueue_t;
 
 typedef struct bqueue_node {
 	list_node_t bqn_node;
-	uint64_t bqn_size;
+	size_t bqn_size;
 } bqueue_node_t;
 
 
-int bqueue_init(bqueue_t *, uint64_t, uint64_t, size_t);
+int bqueue_init(bqueue_t *, uint_t, size_t, size_t);
 void bqueue_destroy(bqueue_t *);
-void bqueue_enqueue(bqueue_t *, void *, uint64_t);
-void bqueue_enqueue_flush(bqueue_t *, void *, uint64_t);
+void bqueue_enqueue(bqueue_t *, void *, size_t);
+void bqueue_enqueue_flush(bqueue_t *, void *, size_t);
 void *bqueue_dequeue(bqueue_t *);
 boolean_t bqueue_empty(bqueue_t *);
 

include/sys/fs/zfs.h

@@ -1758,9 +1758,9 @@ typedef enum {
  * against the cost of COWing a giant block to modify one byte, and the
  * large latency of reading or writing a large block.
  *
- * Note that although blocks up to 16MB are supported, the recordsize
- * property can not be set larger than zfs_max_recordsize (default 1MB).
- * See the comment near zfs_max_recordsize in dsl_dataset.c for details.
+ * The recordsize property can not be set larger than zfs_max_recordsize
+ * (default 16MB on 64-bit and 1MB on 32-bit). See the comment near
+ * zfs_max_recordsize in dsl_dataset.c for details.
  *
  * Note that although the LSIZE field of the blkptr_t can store sizes up
  * to 32MB, the dnode's dn_datablkszsec can only store sizes up to

module/zfs/bqueue.c

@@ -42,8 +42,7 @@ obj2node(bqueue_t *q, void *data)
  * Return 0 on success, or -1 on failure.
  */
 int
-bqueue_init(bqueue_t *q, uint64_t fill_fraction, uint64_t size,
-    size_t node_offset)
+bqueue_init(bqueue_t *q, uint_t fill_fraction, size_t size, size_t node_offset)
 {
 	if (fill_fraction == 0) {
 		return (-1);
@@ -78,22 +77,26 @@ bqueue_destroy(bqueue_t *q)
 }
 
 static void
-bqueue_enqueue_impl(bqueue_t *q, void *data, uint64_t item_size,
-    boolean_t flush)
+bqueue_enqueue_impl(bqueue_t *q, void *data, size_t item_size, boolean_t flush)
 {
 	ASSERT3U(item_size, >, 0);
 	ASSERT3U(item_size, <=, q->bq_maxsize);
 	mutex_enter(&q->bq_lock);
 	obj2node(q, data)->bqn_size = item_size;
-	while (q->bq_size + item_size > q->bq_maxsize) {
+	while (q->bq_size && q->bq_size + item_size > q->bq_maxsize) {
+		/*
+		 * Wake up bqueue_dequeue() thread if already sleeping in order
+		 * to prevent the deadlock condition
+		 */
+		cv_signal(&q->bq_pop_cv);
 		cv_wait_sig(&q->bq_add_cv, &q->bq_lock);
 	}
 	q->bq_size += item_size;
 	list_insert_tail(&q->bq_list, data);
-	if (q->bq_size >= q->bq_maxsize / q->bq_fill_fraction)
-		cv_signal(&q->bq_pop_cv);
 	if (flush)
 		cv_broadcast(&q->bq_pop_cv);
+	else if (q->bq_size >= q->bq_maxsize / q->bq_fill_fraction)
+		cv_signal(&q->bq_pop_cv);
 	mutex_exit(&q->bq_lock);
 }
 
@@ -103,7 +106,7 @@ bqueue_enqueue_impl(bqueue_t *q, void *data, uint64_t item_size,
  * > 0.
  */
 void
-bqueue_enqueue(bqueue_t *q, void *data, uint64_t item_size)
+bqueue_enqueue(bqueue_t *q, void *data, size_t item_size)
 {
 	bqueue_enqueue_impl(q, data, item_size, B_FALSE);
 }
@@ -117,7 +120,7 @@ bqueue_enqueue(bqueue_t *q, void *data, uint64_t item_size)
  * destroy the condvar before the enqueuing thread is done.
  */
 void
-bqueue_enqueue_flush(bqueue_t *q, void *data, uint64_t item_size)
+bqueue_enqueue_flush(bqueue_t *q, void *data, size_t item_size)
 {
 	bqueue_enqueue_impl(q, data, item_size, B_TRUE);
 }
@@ -130,7 +133,7 @@ void *
 bqueue_dequeue(bqueue_t *q)
 {
 	void *ret = NULL;
-	uint64_t item_size;
+	size_t item_size;
 	mutex_enter(&q->bq_lock);
 	while (q->bq_size == 0) {
 		cv_wait_sig(&q->bq_pop_cv, &q->bq_lock);