* 60バイト以下のシンボリックリンクはinodeのi_blockに格納され、データブロックを消費しない。そのぶんアクセスも速い。
* fs/ext3/namei.c
if (l > EXT3_N_BLOCKS * 4) {
inode->i_op = &ext3_symlink_inode_operations;
ext3_set_aops(inode);
/*
* We cannot call page_symlink() with transaction started
* because it calls into ext3_write_begin() which acquires page
* lock which ranks below transaction start (and it can also
* wait for journal commit if we are running out of space). So
* we have to stop transaction now and restart it when symlink
* contents is written.
*
* To keep fs consistent in case of crash, we have to put inode
* to orphan list in the mean time.
*/
drop_nlink(inode);
err = ext3_orphan_add(handle, inode);
ext3_journal_stop(handle);
if (err)
goto err_drop_inode;
err = __page_symlink(inode, symname, l, 1);
if (err)
goto err_drop_inode;
/*
* Now inode is being linked into dir (EXT3_DATA_TRANS_BLOCKS
* + EXT3_INDEX_EXTRA_TRANS_BLOCKS), inode is also modified
*/
handle = ext3_journal_start(dir,
EXT3_DATA_TRANS_BLOCKS(dir->i_sb) +
EXT3_INDEX_EXTRA_TRANS_BLOCKS + 1);
if (IS_ERR(handle)) {
err = PTR_ERR(handle);
goto err_drop_inode;
}
set_nlink(inode, 1);
err = ext3_orphan_del(handle, inode);
if (err) {
ext3_journal_stop(handle);
drop_nlink(inode);
goto err_drop_inode;
}
} else {
inode->i_op = &ext3_fast_symlink_inode_operations;
memcpy((char*)&EXT3_I(inode)->i_data,symname,l);
inode->i_size = l-1;
}