diff mbox series

[RFC,1/2] maple_tree: add __mtree_insert_range function

Message ID 20250405060154.1550858-2-andrewjballance@gmail.com (mailing list archive)
State New
Headers show
Series rust: add support for maple trees | expand

Commit Message

Andrew Ballance April 5, 2025, 6:01 a.m. UTC 
adds the __mtree_insert_range which is identical to mtree_insert_range
but does not aquire ma_lock.
This function is needed for the rust bindings for maple trees because
the locking is handled on the rust side.

Signed-off-by: Andrew Ballance <andrewjballance@gmail.com>
---
 include/linux/maple_tree.h |  2 ++
 lib/maple_tree.c           | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

Comments

Matthew Wilcox April 5, 2025, 3:22 p.m. UTC | #1 
On Sat, Apr 05, 2025 at 01:01:53AM -0500, Andrew Ballance wrote:
> adds the __mtree_insert_range which is identical to mtree_insert_range
> but does not aquire ma_lock.
> This function is needed for the rust bindings for maple trees because
> the locking is handled on the rust side.

No.

The support for external locking is a TEMPORARY HACK.  I've talked
before about why this is and don't feel like explaining it again.
Boqun Feng April 5, 2025, 6:38 p.m. UTC | #2 
On Sat, Apr 05, 2025 at 04:22:34PM +0100, Matthew Wilcox wrote:
> On Sat, Apr 05, 2025 at 01:01:53AM -0500, Andrew Ballance wrote:
> > adds the __mtree_insert_range which is identical to mtree_insert_range
> > but does not aquire ma_lock.
> > This function is needed for the rust bindings for maple trees because
> > the locking is handled on the rust side.
> 
> No.
> 
> The support for external locking is a TEMPORARY HACK.  I've talked
> before about why this is and don't feel like explaining it again.

Does it mean that ideally maple trees should not support external
locking, i.e. it should use its own locking?

(BTw, people usually add some documentation if they don't want to repeat
themselves ;-))

Regards,
Boqun
diff mbox series

Patch

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index cbbcd18d4186..b849d57e627e 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -329,6 +329,8 @@  int mtree_insert(struct maple_tree *mt, unsigned long index,
 		void *entry, gfp_t gfp);
 int mtree_insert_range(struct maple_tree *mt, unsigned long first,
 		unsigned long last, void *entry, gfp_t gfp);
+int __mtree_insert_range(struct maple_tree *mt, unsigned long first,
+		unsigned long last, void *entry, gfp_t gfp);
 int mtree_alloc_range(struct maple_tree *mt, unsigned long *startp,
 		void *entry, unsigned long size, unsigned long min,
 		unsigned long max, gfp_t gfp);
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index f7153ade1be5..e0db5d3b5254 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -6387,6 +6387,43 @@  int mtree_insert_range(struct maple_tree *mt, unsigned long first,
 	return ret;
 }
 EXPORT_SYMBOL(mtree_insert_range);
+/**
+ * __mtree_insert_range() - Insert an entry at a given range if there is no value. without locking
+ * @mt: The maple tree
+ * @first: The start of the range
+ * @last: The end of the range
+ * @entry: The entry to store
+ * @gfp: The GFP_FLAGS to use for allocations.
+ *
+ * Return: 0 on success, -EEXISTS if the range is occupied, -EINVAL on invalid
+ * request, -ENOMEM if memory could not be allocated.
+ * Note that the user needs to manually lock the  tree.
+ */
+int __mtree_insert_range(struct maple_tree *mt, unsigned long first,
+		unsigned long last, void *entry, gfp_t gfp)
+{
+	MA_STATE(ms, mt, first, last);
+	int ret = 0;
+
+	if (WARN_ON_ONCE(xa_is_advanced(entry)))
+		return -EINVAL;
+
+	if (first > last)
+		return -EINVAL;
+
+retry:
+	mas_insert(&ms, entry);
+	if (mas_nomem(&ms, gfp))
+		goto retry;
+
+	if (mas_is_err(&ms))
+		ret = xa_err(ms.node);
+
+	mas_destroy(&ms);
+	return ret;
+
+}
+EXPORT_SYMBOL(__mtree_insert_range);
 
 /**
  * mtree_insert() - Insert an entry at a given index if there is no value.