f2fs: align memory boundary for bitops

For example, in arm64, free_nid_bitmap should be aligned to word size in order
to use bit operations.

Reviewed-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/f2fs.h

···
 	unsigned int nid_cnt[MAX_NID_STATE];	/* the number of free node id */
 	spinlock_t nid_list_lock;	/* protect nid lists ops */
 	struct mutex build_lock;	/* lock for build free nids */
-	unsigned char (*free_nid_bitmap)[NAT_ENTRY_BITMAP_SIZE];
+	unsigned char **free_nid_bitmap;
 	unsigned char *nat_block_bitmap;
 	unsigned short *free_nid_count;	/* free nid count of NAT block */
 

fs/f2fs/node.c

···
 static int init_free_nid_cache(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	int i;
 
-	nm_i->free_nid_bitmap = f2fs_kvzalloc(sbi, nm_i->nat_blocks *
-					NAT_ENTRY_BITMAP_SIZE, GFP_KERNEL);
+	nm_i->free_nid_bitmap = f2fs_kzalloc(sbi, nm_i->nat_blocks *
+				sizeof(unsigned char *), GFP_KERNEL);
 	if (!nm_i->free_nid_bitmap)
 		return -ENOMEM;
+
+	for (i = 0; i < nm_i->nat_blocks; i++) {
+		nm_i->free_nid_bitmap[i] = f2fs_kvzalloc(sbi,
+				NAT_ENTRY_BITMAP_SIZE_ALIGNED, GFP_KERNEL);
+		if (!nm_i->free_nid_bitmap)
+			return -ENOMEM;
+	}
 
 	nm_i->nat_block_bitmap = f2fs_kvzalloc(sbi, nm_i->nat_blocks / 8,
 								GFP_KERNEL);
···
 	up_write(&nm_i->nat_tree_lock);
 
 	kvfree(nm_i->nat_block_bitmap);
-	kvfree(nm_i->free_nid_bitmap);
+	if (nm_i->free_nid_bitmap) {
+		int i;
+
+		for (i = 0; i < nm_i->nat_blocks; i++)
+			kvfree(nm_i->free_nid_bitmap[i]);
+		kfree(nm_i->free_nid_bitmap);
+	}
 	kvfree(nm_i->free_nid_count);
 
 	kfree(nm_i->nat_bitmap);

include/linux/f2fs_fs.h

···
  */
 #define NAT_ENTRY_PER_BLOCK (PAGE_SIZE / sizeof(struct f2fs_nat_entry))
 #define NAT_ENTRY_BITMAP_SIZE	((NAT_ENTRY_PER_BLOCK + 7) / 8)
+#define NAT_ENTRY_BITMAP_SIZE_ALIGNED				\
+	((NAT_ENTRY_BITMAP_SIZE + BITS_PER_LONG - 1) /		\
+	BITS_PER_LONG * BITS_PER_LONG)
+
 
 struct f2fs_nat_entry {
 	__u8 version;		/* latest version of cached nat entry */