mufs: reduce memory footprint of mufs_shrink_tree()

source/fs/mufs/tree.c

@@ -181,8 +181,6 @@ int mufs_shrink_tree(struct mufs_tree *tree, uint32_t max_size)
 {
 	struct mufs *fs = tree->fs;
 	struct flash_dev *dev = fs->dev;
-	char data[1 << dev->log2_block_size];
-	uint32_t *table = (uint32_t *)data;
 	size_t index;
 	uint32_t base, size;
 	uint8_t depth;
@@ -198,11 +196,10 @@ int mufs_shrink_tree(struct mufs_tree *tree, uint32_t max_size)
 		index = max_size >> ((depth - 1) * fs->log2_nentries +
 			dev->log2_block_size);
 
-		if (flash_read(dev, base, data, sizeof data) == 0)
-			return -1;
-
 		if (index <= 1) {
-			tree->root = table[0];
+			if (flash_read(dev, base, &tree->root, sizeof tree->root) == 0)
+				return -1;
+
 			--tree->depth;
 
 			mufs_free_block(fs, base);
@@ -210,12 +207,11 @@ int mufs_shrink_tree(struct mufs_tree *tree, uint32_t max_size)
 			continue;
 		}
 
-		for (; index < (UINT32_C(1) << fs->log2_nentries); ++index) {
-			table[index] = 0;
-		}
+		if (flash_write0(dev, base + index * sizeof(uint32_t), (UINT32_C(1) <<
+			dev->log2_block_size) - index * sizeof(uint32_t)) == 0)
+			return -1;
 
-		if (flash_write(dev, base << dev->log2_block_size, data,
-			sizeof data) == 0)
+		if (flash_sync(dev) < 0)
 			return -1;
 	}