nilfs2: super root size should change depending on inode size

The size of super root structure depends on inode size, so
NILFS_SR_BYTES macro should be a function of the inode size.  This
fixes the issue.

Even though a different size value will be written for a possible
future filesystem with extended inode, but fortunately this does not
break disk format compatibility.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/segbuf.c

@@ -239,12 +239,15 @@ nilfs_segbuf_fill_in_super_root_crc(struct nilfs_segment_buffer *segbuf,
 				    u32 seed)
 {
 	struct nilfs_super_root *raw_sr;
+	struct the_nilfs *nilfs = segbuf->sb_super->s_fs_info;
+	unsigned srsize;
 	u32 crc;
 
 	raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
+	srsize = NILFS_SR_BYTES(nilfs->ns_inode_size);
 	crc = crc32_le(seed,
 		       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
-		       NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
+		       srsize - sizeof(raw_sr->sr_sum));
 	raw_sr->sr_sum = cpu_to_le32(crc);
 }
 

fs/nilfs2/segment.c

@@ -894,7 +894,7 @@ static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
 	bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
 	raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 
-	raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
+	raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES(isz));
 	raw_sr->sr_nongc_ctime
 		= cpu_to_le64(nilfs_doing_gc() ?
 			      nilfs->ns_nongc_ctime : sci->sc_seg_ctime);

include/linux/nilfs2_fs.h

@@ -107,7 +107,7 @@ struct nilfs_super_root {
 #define NILFS_SR_DAT_OFFSET(inode_size)     NILFS_SR_MDT_OFFSET(inode_size, 0)
 #define NILFS_SR_CPFILE_OFFSET(inode_size)  NILFS_SR_MDT_OFFSET(inode_size, 1)
 #define NILFS_SR_SUFILE_OFFSET(inode_size)  NILFS_SR_MDT_OFFSET(inode_size, 2)
-#define NILFS_SR_BYTES                  (sizeof(struct nilfs_super_root))
+#define NILFS_SR_BYTES(inode_size)	    NILFS_SR_MDT_OFFSET(inode_size, 3)
 
 /*
  * Maximal mount counts