ramdisk加密试验出错

wsgtrsys

主要修改了rd_blkdev_pagecache_IO函数，
http://lxr.linux.no/source/drivers/block/rd.c#L201

在242行处加入了取反运算，

240                 vec_offset += count; 241 242                 memcpy(dst, src, count); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;for (i=0;i<count;i++)    //新加入 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dst[i]=~dst[i];

然后编译内核，重启后mke2fs /dev/ram没问题，mount也没问题。
但是进入mount目录进行文件操作时出错，

[root@debian ~]# mke2fs /dev/ram0
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
1024 inodes, 4096 blocks
204 blocks (4.98%) reserved for the super user
First data block=1
Maximum filesystem blocks=4194304
1 block group
8192 blocks per group, 8192 fragments per group
1024 inodes per group

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 36 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@debian ~]# mount /dev/ram0 aa
[root@debian ~]# cd aa
[root@debian aa]# ls
/bin/ls: reading directory .: Input/output error
[root@debian aa]# cp ../a.tgz .
cp: cannot create regular file `./a.tgz': Input/output error
[root@debian aa]#

系统输出信息：

EXT2-fs error (device ram0): ext2_check_page: bad entry in directory #2: unaligned directory entry - offset=0, inode=4294967293, rec_len=65523, name_len=254
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
EXT2-fs error (device ram0): ext2_check_page: bad entry in directory #2: unaligned directory entry - offset=0, inode=4294967293, rec_len=65523, name_len=254
EXT2-fs error (device ram0): ext2_readdir: bad page in #2
EXT2-fs error (device ram0): ext2_readdir: bad page in #2

不知道是哪里的问题？

[ 本帖最后由 wsgtrsys 于 2007-7-20 11:35 编辑 ]

wsgtrsys

也许是因为缓存的原因？

金西

什么时候才能达到自己修改内核代码

sisi8408

有入有出，乃为好/全/上。
只入不出，苦不堪言，不入也罢。

wwfonline

当数据被读入到page cache中以后，是以加密的形式存在的，如果下次再读的话，不会再经过make_request再走rd_blkdev_pagecache_IO进行解密了，数据也就自然错了。