mm: cma: add functions to get region pages counters

Here are two functions that provide interface to compute/get used size and
size of biggest free chunk in cma region.  Add that information to
debugfs.

[[email protected]: move debug code from cma.c into cma_debug.c]
[[email protected]: move code from cma_get_used() and cma_get_maxchunk() to cma_used_get() and cma_maxchunk_get()]
Signed-off-by: Dmitry Safonov <[email protected]>
Signed-off-by: Stefan Strogin <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Pintu Kumar <[email protected]>
Cc: Weijie Yang <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Vyacheslav Tyrtov <[email protected]>
Cc: Aleksei Mateosian <[email protected]>
Signed-off-by: Stefan Strogin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/cma_debug.c

@@ -33,6 +33,44 @@ static int cma_debugfs_get(void *data, u64 *val)
 
 DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
 
+static int cma_used_get(void *data, u64 *val)
+{
+	struct cma *cma = data;
+	unsigned long used;
+
+	mutex_lock(&cma->lock);
+	/* pages counter is smaller than sizeof(int) */
+	used = bitmap_weight(cma->bitmap, (int)cma->count);
+	mutex_unlock(&cma->lock);
+	*val = (u64)used << cma->order_per_bit;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(cma_used_fops, cma_used_get, NULL, "%llu\n");
+
+static int cma_maxchunk_get(void *data, u64 *val)
+{
+	struct cma *cma = data;
+	unsigned long maxchunk = 0;
+	unsigned long start, end = 0;
+
+	mutex_lock(&cma->lock);
+	for (;;) {
+		start = find_next_zero_bit(cma->bitmap, cma->count, end);
+		if (start >= cma->count)
+			break;
+		end = find_next_bit(cma->bitmap, cma->count, start);
+		maxchunk = max(end - start, maxchunk);
+	}
+	mutex_unlock(&cma->lock);
+	*val = (u64)maxchunk << cma->order_per_bit;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(cma_maxchunk_fops, cma_maxchunk_get, NULL, "%llu\n");
+
 static void cma_add_to_cma_mem_list(struct cma *cma, struct cma_mem *mem)
 {
 	spin_lock(&cma->mem_head_lock);
@@ -149,6 +187,8 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
 				&cma->count, &cma_debugfs_fops);
 	debugfs_create_file("order_per_bit", S_IRUGO, tmp,
 				&cma->order_per_bit, &cma_debugfs_fops);
+	debugfs_create_file("used", S_IRUGO, tmp, cma, &cma_used_fops);
+	debugfs_create_file("maxchunk", S_IRUGO, tmp, cma, &cma_maxchunk_fops);
 
 	u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
 	debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap, u32s);