Function name and comment updates

Rename certain functions for more consistency when they share common 
features. Make comments clearer about what arguments should be passed 
to the insert and add functions.

Reviewed by: Sara Hartse <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Matt Ahrens <[email protected]>
Signed-off-by: Paul Dagnelie <[email protected]>
Closes #9441 

4 files changed, 40 insertions, 16 deletions

diff --git a/include/sys/btree.h b/include/sys/btree.h
index 1673b5217..9fe2534df 100644
--- a/include/sys/btree.h
+++ b/include/sys/btree.h
@@ -131,10 +131,10 @@ void zfs_btree_create(zfs_btree_t *, int (*) (const void *, const void *),
 /*
  * Find a node with a matching value in the tree. Returns the matching node
  * found. If not found, it returns NULL and then if "where" is not NULL it sets
- * "where" for use with zfs_btree_insert() or zfs_btree_nearest().
+ * "where" for use with zfs_btree_add_idx() or zfs_btree_nearest().
  *
  * node   - node that has the value being looked for
- * where  - position for use with zfs_btree_nearest() or zfs_btree_insert(),
+ * where  - position for use with zfs_btree_nearest() or zfs_btree_add_idx(),
  *          may be NULL
  */
 void *zfs_btree_find(zfs_btree_t *, const void *, zfs_btree_index_t *);
@@ -145,17 +145,20 @@ void *zfs_btree_find(zfs_btree_t *, const void *, zfs_btree_index_t *);
  * node   - the node to insert
  * where  - position as returned from zfs_btree_find()
  */
-void zfs_btree_insert(zfs_btree_t *, const void *, const zfs_btree_index_t *);
+void zfs_btree_add_idx(zfs_btree_t *, const void *, const zfs_btree_index_t *);
 
 /*
- * Return the first or last valued node in the tree. Will return NULL
- * if the tree is empty.
+ * Return the first or last valued node in the tree. Will return NULL if the
+ * tree is empty. The index can be NULL if the location of the first or last
+ * element isn't required.
  */
 void *zfs_btree_first(zfs_btree_t *, zfs_btree_index_t *);
 void *zfs_btree_last(zfs_btree_t *, zfs_btree_index_t *);
 
 /*
- * Return the next or previous valued node in the tree.
+ * Return the next or previous valued node in the tree. The second index can
+ * safely be NULL, if the location of the next or previous value isn't
+ * required.
  */
 void *zfs_btree_next(zfs_btree_t *, const zfs_btree_index_t *,
     zfs_btree_index_t *);
@@ -169,7 +172,9 @@ void *zfs_btree_get(zfs_btree_t *, zfs_btree_index_t *);
 
 /*
  * Add a single value to the tree. The value must not compare equal to any
- * other node already in the tree.
+ * other node already in the tree. Note that the value will be copied out, not
+ * inserted directly. It is safe to free or destroy the value once this
+ * function returns.
  */
 void zfs_btree_add(zfs_btree_t *, const void *);
 
@@ -183,7 +188,7 @@ void zfs_btree_remove(zfs_btree_t *, const void *);
 /*
  * Remove the value at the given location from the tree.
  */
-void zfs_btree_remove_from(zfs_btree_t *, zfs_btree_index_t *);
+void zfs_btree_remove_idx(zfs_btree_t *, zfs_btree_index_t *);
 
 /*
  * Return the number of nodes in the tree
diff --git a/module/zfs/btree.c b/module/zfs/btree.c
index 8f514caab..f099eb67c 100644
--- a/module/zfs/btree.c
+++ b/module/zfs/btree.c
@@ -980,7 +980,7 @@ zfs_btree_bulk_finish(zfs_btree_t *tree)
  * Insert value into tree at the location specified by where.
  */
 void
-zfs_btree_insert(zfs_btree_t *tree, const void *value,
+zfs_btree_add_idx(zfs_btree_t *tree, const void *value,
     const zfs_btree_index_t *where)
 {
 	zfs_btree_index_t idx = {0};
@@ -1294,7 +1294,7 @@ zfs_btree_add(zfs_btree_t *tree, const void *node)
 {
 	zfs_btree_index_t where = {0};
 	VERIFY3P(zfs_btree_find(tree, node, &where), ==, NULL);
-	zfs_btree_insert(tree, node, &where);
+	zfs_btree_add_idx(tree, node, &where);
 }
 
 /* Helper function to free a tree node. */
@@ -1542,7 +1542,7 @@ zfs_btree_remove_from_node(zfs_btree_t *tree, zfs_btree_core_t *node,
 
 /* Remove the element at the specific location. */
 void
-zfs_btree_remove_from(zfs_btree_t *tree, zfs_btree_index_t *where)
+zfs_btree_remove_idx(zfs_btree_t *tree, zfs_btree_index_t *where)
 {
 	size_t size = tree->bt_elem_size;
 	zfs_btree_hdr_t *hdr = where->bti_node;
@@ -1778,7 +1778,7 @@ zfs_btree_remove(zfs_btree_t *tree, const void *value)
 {
 	zfs_btree_index_t where = {0};
 	VERIFY3P(zfs_btree_find(tree, value, &where), !=, NULL);
-	zfs_btree_remove_from(tree, &where);
+	zfs_btree_remove_idx(tree, &where);
 }
 
 /* Return the number of elements in the tree. */
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index 3eacb42f1..b848f7ef3 100644
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -2925,13 +2925,23 @@ scan_io_queue_fetch_ext(dsl_scan_io_queue_t *queue)
 		if (zfs_scan_issue_strategy == 1) {
 			return (range_tree_first(rt));
 		} else if (zfs_scan_issue_strategy == 2) {
+			/*
+			 * We need to get the original entry in the by_addr
+			 * tree so we can modify it.
+			 */
 			range_seg_t *size_rs =
 			    zfs_btree_first(&queue->q_exts_by_size, NULL);
+			if (size_rs == NULL)
+				return (NULL);
 			uint64_t start = rs_get_start(size_rs, rt);
 			uint64_t size = rs_get_end(size_rs, rt) - start;
 			range_seg_t *addr_rs = range_tree_find(rt, start,
 			    size);
 			ASSERT3P(addr_rs, !=, NULL);
+			ASSERT3U(rs_get_start(size_rs, rt), ==,
+			    rs_get_start(addr_rs, rt));
+			ASSERT3U(rs_get_end(size_rs, rt), ==,
+			    rs_get_end(addr_rs, rt));
 			return (addr_rs);
 		}
 	}
@@ -2948,12 +2958,21 @@ scan_io_queue_fetch_ext(dsl_scan_io_queue_t *queue)
 	if (scn->scn_checkpointing) {
 		return (range_tree_first(rt));
 	} else if (scn->scn_clearing) {
+		/*
+		 * We need to get the original entry in the by_addr
+		 * tree so we can modify it.
+		 */
 		range_seg_t *size_rs = zfs_btree_first(&queue->q_exts_by_size,
 		    NULL);
+		if (size_rs == NULL)
+			return (NULL);
 		uint64_t start = rs_get_start(size_rs, rt);
 		uint64_t size = rs_get_end(size_rs, rt) - start;
 		range_seg_t *addr_rs = range_tree_find(rt, start, size);
 		ASSERT3P(addr_rs, !=, NULL);
+		ASSERT3U(rs_get_start(size_rs, rt), ==, rs_get_start(addr_rs,
+		    rt));
+		ASSERT3U(rs_get_end(size_rs, rt), ==, rs_get_end(addr_rs, rt));
 		return (addr_rs);
 	} else {
 		return (NULL);
diff --git a/module/zfs/range_tree.c b/module/zfs/range_tree.c
index 0b369a438..1559605c2 100644
--- a/module/zfs/range_tree.c
+++ b/module/zfs/range_tree.c
@@ -349,7 +349,7 @@ range_tree_add_impl(void *arg, uint64_t start, uint64_t size, uint64_t fill)
 		uint64_t before_start = rs_get_start_raw(rs_before, rt);
 		uint64_t before_fill = rs_get_fill(rs_before, rt);
 		uint64_t after_fill = rs_get_fill(rs_after, rt);
-		zfs_btree_remove_from(&rt->rt_root, &where_before);
+		zfs_btree_remove_idx(&rt->rt_root, &where_before);
 
 		/*
 		 * We have to re-find the node because our old reference is
@@ -385,7 +385,7 @@ range_tree_add_impl(void *arg, uint64_t start, uint64_t size, uint64_t fill)
 		rs_set_start(rs, rt, start);
 		rs_set_end(rs, rt, end);
 		rs_set_fill(rs, rt, fill);
-		zfs_btree_insert(&rt->rt_root, rs, &where);
+		zfs_btree_add_idx(&rt->rt_root, rs, &where);
 	}
 
 	if (gap != 0) {
@@ -488,7 +488,7 @@ range_tree_remove_impl(range_tree_t *rt, uint64_t start, uint64_t size,
 
 		rs_copy(rs, &rs_tmp, rt);
 		if (zfs_btree_next(&rt->rt_root, &where, &where) != NULL)
-			zfs_btree_insert(&rt->rt_root, &newseg, &where);
+			zfs_btree_add_idx(&rt->rt_root, &newseg, &where);
 		else
 			zfs_btree_add(&rt->rt_root, &newseg);
 
@@ -503,7 +503,7 @@ range_tree_remove_impl(range_tree_t *rt, uint64_t start, uint64_t size,
 		rs_set_start(rs, rt, end);
 		rs_copy(rs, &rs_tmp, rt);
 	} else {
-		zfs_btree_remove_from(&rt->rt_root, &where);
+		zfs_btree_remove_idx(&rt->rt_root, &where);
 		rs = NULL;
 	}