From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Mon, 10 Dec 2018 17:15:27 +0000 (-0500)
Subject: maple_tree: Don't assume 16 byte alignment
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=55d029aa5f13b002fe0e64a1e27c00b3be5c978c;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Don't assume 16 byte alignment

Assume the allocations are 8 byte aligned, so only use the last two bits
to indicate the requested allocation.  Test and return the allocation
count.

Also, fix a small issue in decrementing the requested count before we
actually have succeeded in allocating.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 8a9c1c20fc8b..57c0b554f6d1 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -63,28 +63,30 @@ static inline void *ma_mk_node(const struct maple_node *node)
 	return (void *)((unsigned long)node | 2);
 }
 
-static inline void ma_set_alloc_cnt(struct maple_state *ms, int count)
+static inline struct maple_node *ma_get_alloc(const struct maple_state *ms)
 {
-	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc & ~0x03);
-	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc | count);
+	return (struct maple_node *)((unsigned long)ms->alloc & ~0x0F);
 }
 static inline int ma_get_alloc_cnt(const struct maple_state *ms)
 {
-	return (int)((unsigned long)ms->alloc & 3);
+	struct maple_node *node = ma_get_alloc(ms);
+
+	if (!node)
+		return 0;
+	if (!node->slot[0])
+		return 1;
+	if (!node->slot[1])
+		return 2;
+	return 3;
 }
 static inline void ma_set_alloc_req(struct maple_state *ms, int count)
 {
-	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc & ~0x0C);
-	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc |
-			(count << 2));
+	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc & ~0x03);
+	ms->alloc = (struct maple_node *)((unsigned long)ms->alloc | count);
 }
 static inline int ma_get_alloc_req(const struct maple_state *ms)
 {
-	return (int)(((unsigned long)ms->alloc & 0x0C) >> 2);
-}
-static inline struct maple_node *ma_get_alloc(const struct maple_state *ms)
-{
-	return (struct maple_node *)((unsigned long)ms->alloc & ~0x0F);
+	return (int)(((unsigned long)ms->alloc & 0x03));
 }
 static inline struct maple_node *ma_next_alloc(struct maple_state *ms)
 {
@@ -102,7 +104,6 @@ static inline struct maple_node *ma_next_alloc(struct maple_state *ms)
 	} else {
 		smn = (struct maple_node*)mn->slot[cnt - 1];
 		mn->slot[cnt - 1] = NULL;
-		ma_set_alloc_cnt(ms, cnt);
 		mn = smn;
 	}
 
@@ -150,18 +151,17 @@ static void maple_new_node(struct maple_state *ms, gfp_t gfp)
 
 	slot = allocated - 1;
 	while (req > 0) {
-		req--;
 		smn = kzalloc(sizeof(*mn), gfp);
 		if (!smn)
 			goto slot_failed;
 		smn->parent = NULL;
 		mn->slot[slot++] = smn;
+		req--;
 		allocated++;
 	}
 
 slot_failed:
 	ms->alloc = mn;
-	ma_set_alloc_cnt(ms, allocated);
 	ma_set_alloc_req(ms, req);
 
 list_failed: