omfs_get_block
return block_read_full_folio(folio, omfs_get_block);
mpage_readahead(rac, omfs_get_block);
return mpage_writepages(mapping, wbc, omfs_get_block);
ret = block_write_begin(mapping, pos, len, foliop, omfs_get_block);
return generic_block_bmap(mapping, block, omfs_get_block);