gfs2_get_extent
int gfs2_get_extent(struct inode *inode, u64 lblock, u64 *dblock,
error = gfs2_get_extent(&ip->i_inode, lblock,
ret = gfs2_get_extent(jd->jd_inode, lblock, &dblock, &extlen);
error = gfs2_get_extent(&ip->i_inode, x, &dblock, &extlen);
error = gfs2_get_extent(&ip->i_inode, blk, &dblock, &extlen);