Commit cfb0a4bf authored by Ryusuke Konishi's avatar Ryusuke Konishi
Browse files

nilfs2: add routine to move secondary super block 



After resizing the filesystem, the secondary super block must be moved
to a new location.  This adds a helper function for this.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
parent 619205da

fs/nilfs2/super.c

+57 −0
Original line number Diff line number Diff line
@@ -347,6 +347,63 @@ int nilfs_cleanup_super(struct super_block *sb) 
	return ret;

}



/**

 * nilfs_move_2nd_super - relocate secondary super block

 * @sb: super block instance

 * @sb2off: new offset of the secondary super block (in bytes)

 */

static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)

{

	struct the_nilfs *nilfs = sb->s_fs_info;

	struct buffer_head *nsbh;

	struct nilfs_super_block *nsbp;

	sector_t blocknr, newblocknr;

	unsigned long offset;

	int sb2i = -1;  /* array index of the secondary superblock */

	int ret = 0;



	/* nilfs->ns_sem must be locked by the caller. */

	if (nilfs->ns_sbh[1] &&

	    nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {

		sb2i = 1;

		blocknr = nilfs->ns_sbh[1]->b_blocknr;

	} else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {

		sb2i = 0;

		blocknr = nilfs->ns_sbh[0]->b_blocknr;

	}

	if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)

		goto out;  /* super block location is unchanged */



	/* Get new super block buffer */

	newblocknr = sb2off >> nilfs->ns_blocksize_bits;

	offset = sb2off & (nilfs->ns_blocksize - 1);

	nsbh = sb_getblk(sb, newblocknr);

	if (!nsbh) {

		printk(KERN_WARNING

		       "NILFS warning: unable to move secondary superblock "

		       "to block %llu\n", (unsigned long long)newblocknr);

		ret = -EIO;

		goto out;

	}

	nsbp = (void *)nsbh->b_data + offset;

	memset(nsbp, 0, nilfs->ns_blocksize);



	if (sb2i >= 0) {

		memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);

		brelse(nilfs->ns_sbh[sb2i]);

		nilfs->ns_sbh[sb2i] = nsbh;

		nilfs->ns_sbp[sb2i] = nsbp;

	} else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {

		/* secondary super block will be restored to index 1 */

		nilfs->ns_sbh[1] = nsbh;

		nilfs->ns_sbp[1] = nsbp;

	} else {

		brelse(nsbh);

	}

out:

	return ret;

}



static void nilfs_put_super(struct super_block *sb)

{

	struct the_nilfs *nilfs = sb->s_fs_info;