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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: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi 2011-05-05 01:23:57 +09:00
parent 619205da5b
commit cfb0a4bfd8
1 changed files with 57 additions and 0 deletions
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57
fs/nilfs2/super.c
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@ -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;