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1628 |
jcastillo |
/*
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* linux/fs/umsdos/inode.c
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*
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* Written 1993 by Jacques Gelinas
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* Inspired from linux/fs/msdos/... by Werner Almesberger
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*
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/msdos_fs.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/errno.h>
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#include <asm/segment.h>
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#include <linux/string.h>
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#include <linux/stat.h>
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#include <linux/umsdos_fs.h>
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struct inode *pseudo_root=NULL; /* Useful to simulate the pseudo DOS */
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/* directory. See UMSDOS_readdir_x() */
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/* #Specification: convention / PRINTK Printk and printk
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Here is the convention for the use of printk inside fs/umsdos
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printk carry important message (error or status).
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Printk is for debugging (it is a macro defined at the beginning of
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most source.
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PRINTK is a nulled Printk macro.
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This convention makes the source easier to read, and Printk easier
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to shut off.
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*/
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#define PRINTK(x)
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#define Printk(x) printk x
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void UMSDOS_put_inode(struct inode *inode)
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{
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PRINTK (("put inode %x owner %x pos %d dir %x\n",inode
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,inode->u.umsdos_i.i_emd_owner,inode->u.umsdos_i.pos
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,inode->u.umsdos_i.i_emd_dir));
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if (inode != NULL && inode == pseudo_root){
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printk ("Umsdos: Oops releasing pseudo_root. Notify jacques@solucorp.qc.ca\n");
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}
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fat_put_inode(inode);
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}
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void UMSDOS_put_super(struct super_block *sb)
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{
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msdos_put_super(sb);
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MOD_DEC_USE_COUNT;
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}
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void UMSDOS_statfs(struct super_block *sb,struct statfs *buf, int bufsiz)
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{
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fat_statfs(sb,buf,bufsiz);
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}
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/*
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Call msdos_lookup, but set back the original msdos function table.
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Return 0 if ok, or a negative error code if not.
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*/
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int umsdos_real_lookup (
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struct inode *dir,
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const char *name,
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int len,
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struct inode **result) /* Will hold inode of the file, if successful */
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{
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int ret;
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dir->i_count++;
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ret = msdos_lookup (dir,name,len,result);
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return ret;
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}
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/*
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Complete the setup of an directory inode.
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First, it completes the function pointers, then
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it locates the EMD file. If the EMD is there, then plug the
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umsdos function table. If not, use the msdos one.
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*/
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void umsdos_setup_dir_inode (struct inode *inode)
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{
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inode->u.umsdos_i.i_emd_dir = 0;
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{
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struct inode *emd_dir = umsdos_emd_dir_lookup (inode,0);
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extern struct inode_operations umsdos_rdir_inode_operations;
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inode->i_op = emd_dir != NULL
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? &umsdos_dir_inode_operations
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: &umsdos_rdir_inode_operations;
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iput (emd_dir);
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}
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}
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/*
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Add some info into an inode so it can find its owner quickly
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*/
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void umsdos_set_dirinfo(
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struct inode *inode,
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struct inode *dir,
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off_t f_pos)
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{
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struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
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inode->u.umsdos_i.i_dir_owner = dir->i_ino;
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inode->u.umsdos_i.i_emd_owner = emd_owner->i_ino;
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iput (emd_owner);
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inode->u.umsdos_i.pos = f_pos;
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}
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/*
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Tells if an Umsdos inode has been "patched" once.
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Return != 0 if so.
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*/
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int umsdos_isinit (struct inode *inode)
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{
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#if 1
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return inode->u.umsdos_i.i_emd_owner != 0;
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#elif 0
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return inode->i_atime != 0;
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#else
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return inode->i_count > 1;
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#endif
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}
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/*
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Connect the proper tables in the inode and add some info.
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*/
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void umsdos_patch_inode (
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struct inode *inode,
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struct inode *dir, /* May be NULL */
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off_t f_pos)
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{
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/*
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This function is called very early to setup the inode, somewhat
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too early (called by UMSDOS_read_inode). At this point, we can't
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do to much, such as lookup up EMD files and so on. This causes
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confusion in the kernel. This is why some initialisation
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will be done when dir != NULL only.
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UMSDOS do run piggy back on top of msdos fs. It looks like something
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is missing in the VFS to accommodate stacked fs. Still unclear what
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(quite honestly).
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Well, maybe one! A new entry "may_unmount" which would allow
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the stacked fs to allocate some inode permanently and release
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them at the end. Doing that now introduce a problem. unmount
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always fail because some inodes are in use.
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*/
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if (!umsdos_isinit(inode)){
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inode->u.umsdos_i.i_emd_dir = 0;
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if (S_ISREG(inode->i_mode)){
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if (inode->i_op->bmap != NULL){
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inode->i_op = &umsdos_file_inode_operations;
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}else{
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inode->i_op = &umsdos_file_inode_operations_no_bmap;
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}
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}else if (S_ISDIR(inode->i_mode)){
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if (dir != NULL){
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umsdos_setup_dir_inode(inode);
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}
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}else if (S_ISLNK(inode->i_mode)){
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inode->i_op = &umsdos_symlink_inode_operations;
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}else if (S_ISCHR(inode->i_mode)){
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inode->i_op = &chrdev_inode_operations;
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}else if (S_ISBLK(inode->i_mode)){
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inode->i_op = &blkdev_inode_operations;
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}else if (S_ISFIFO(inode->i_mode)){
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init_fifo(inode);
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}
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if (dir != NULL){
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/* #Specification: inode / umsdos info
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The first time an inode is seen (inode->i_count == 1),
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the inode number of the EMD file which control this inode
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is tagged to this inode. It allows operation such
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as notify_change to be handled.
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*/
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/*
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This is done last because it also control the
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status of umsdos_isinit()
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*/
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umsdos_set_dirinfo (inode,dir,f_pos);
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}
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}else if (dir != NULL){
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/*
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Test to see if the info is maintained.
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This should be removed when the file system will be proven.
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*/
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struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
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iput (emd_owner);
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if (emd_owner->i_ino != inode->u.umsdos_i.i_emd_owner){
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printk ("UMSDOS: *** EMD_OWNER ??? *** ino = %ld %ld <> %ld "
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,inode->i_ino,emd_owner->i_ino,inode->u.umsdos_i.i_emd_owner);
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}
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}
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}
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/*
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Get the inode of the directory which owns this inode.
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Return 0 if ok, -EIO if error.
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*/
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int umsdos_get_dirowner(
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struct inode *inode,
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struct inode **result) /* Hold NULL if any error */
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/* else, the inode of the directory */
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{
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int ret = -EIO;
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unsigned long ino = inode->u.umsdos_i.i_dir_owner;
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*result = NULL;
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if (ino == 0){
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printk ("UMSDOS: umsdos_get_dirowner ino == 0\n");
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}else{
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struct inode *dir = *result = iget(inode->i_sb,ino);
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if (dir != NULL){
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umsdos_patch_inode (dir,NULL,0);
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ret = 0;
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}
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}
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return ret;
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}
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/*
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Load an inode from disk.
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*/
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void UMSDOS_read_inode(struct inode *inode)
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{
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PRINTK (("read inode %x ino = %d ",inode,inode->i_ino));
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msdos_read_inode(inode);
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PRINTK (("ino = %d %ld\n",inode->i_ino,inode->i_count));
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if (S_ISDIR(inode->i_mode)
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&& (inode->u.umsdos_i.u.dir_info.creating != 0
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|| inode->u.umsdos_i.u.dir_info.looking != 0
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|| waitqueue_active(&inode->u.umsdos_i.u.dir_info.p))){
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Printk (("read inode %d %d %p\n"
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,inode->u.umsdos_i.u.dir_info.creating
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,inode->u.umsdos_i.u.dir_info.looking
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,inode->u.umsdos_i.u.dir_info.p));
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}
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/* #Specification: Inode / post initialisation
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To completely initialise an inode, we need access to the owner
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directory, so we can locate more info in the EMD file. This is
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not available the first time the inode is access, we use
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a value in the inode to tell if it has been finally initialised.
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| 242 |
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At first, we have tried testing i_count but it was causing
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| 243 |
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problem. It is possible that two or more process use the
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| 244 |
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newly accessed inode. While the first one block during
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| 245 |
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the initialisation (probably while reading the EMD file), the
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| 246 |
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others believe all is well because i_count > 1. They go banana
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| 247 |
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with a broken inode. See umsdos_lookup_patch and umsdos_patch_inode.
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*/
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| 249 |
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umsdos_patch_inode(inode,NULL,0);
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| 250 |
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}
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| 251 |
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| 252 |
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/*
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| 253 |
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Update the disk with the inode content
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| 254 |
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*/
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| 255 |
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void UMSDOS_write_inode(struct inode *inode)
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| 256 |
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{
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| 257 |
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struct iattr newattrs;
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| 258 |
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| 259 |
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PRINTK (("UMSDOS_write_inode emd %d\n",inode->u.umsdos_i.i_emd_owner));
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| 260 |
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fat_write_inode(inode);
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| 261 |
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newattrs.ia_mtime = inode->i_mtime;
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| 262 |
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newattrs.ia_atime = inode->i_atime;
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| 263 |
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newattrs.ia_ctime = inode->i_ctime;
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| 264 |
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newattrs.ia_valid = ATTR_MTIME | ATTR_ATIME | ATTR_CTIME;
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| 265 |
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/*
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| 266 |
|
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UMSDOS_notify_change is convenient to call here
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| 267 |
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to update the EMD entry associated with this inode.
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| 268 |
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But it has the side effect to re"dirt" the inode.
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| 269 |
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*/
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| 270 |
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UMSDOS_notify_change (inode, &newattrs);
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| 271 |
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inode->i_dirt = 0;
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| 272 |
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}
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| 273 |
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| 274 |
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int UMSDOS_notify_change(struct inode *inode, struct iattr *attr)
|
| 275 |
|
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{
|
| 276 |
|
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int ret = 0;
|
| 277 |
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|
| 278 |
|
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if ((ret = inode_change_ok(inode, attr)) != 0)
|
| 279 |
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return ret;
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| 280 |
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|
| 281 |
|
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if (inode->i_nlink > 0){
|
| 282 |
|
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/* #Specification: notify_change / i_nlink > 0
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| 283 |
|
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notify change is only done for inode with nlink > 0. An inode
|
| 284 |
|
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with nlink == 0 is no longer associated with any entry in
|
| 285 |
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the EMD file, so there is nothing to update.
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| 286 |
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*/
|
| 287 |
|
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unsigned long i_emd_owner = inode->u.umsdos_i.i_emd_owner;
|
| 288 |
|
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if (inode == inode->i_sb->s_mounted){
|
| 289 |
|
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/* #Specification: root inode / attributes
|
| 290 |
|
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I don't know yet how this should work. Normally
|
| 291 |
|
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the attributes (permissions bits, owner, times) of
|
| 292 |
|
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a directory are stored in the EMD file of its parent.
|
| 293 |
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|
| 294 |
|
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One thing we could do is store the attributes of the root
|
| 295 |
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inode in its own EMD file. A simple entry named "." could
|
| 296 |
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be used for this special case. It would be read once
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| 297 |
|
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when the file system is mounted and update in
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| 298 |
|
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UMSDOS_notify_change() (right here).
|
| 299 |
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|
| 300 |
|
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I am not sure of the behavior of the root inode for
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| 301 |
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a real UNIX file system. For now, this is a nop.
|
| 302 |
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*/
|
| 303 |
|
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}else if (i_emd_owner != 0xffffffff && i_emd_owner != 0){
|
| 304 |
|
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/* This inode is not a EMD file nor an inode used internally
|
| 305 |
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by MSDOS, so we can update its status.
|
| 306 |
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See emd.c
|
| 307 |
|
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*/
|
| 308 |
|
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struct inode *emd_owner = iget (inode->i_sb,i_emd_owner);
|
| 309 |
|
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PRINTK (("notify change %p ",inode));
|
| 310 |
|
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if (emd_owner == NULL){
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| 311 |
|
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printk ("UMSDOS: emd_owner = NULL ???");
|
| 312 |
|
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ret = -EPERM;
|
| 313 |
|
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}else{
|
| 314 |
|
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struct file filp;
|
| 315 |
|
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struct umsdos_dirent entry;
|
| 316 |
|
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filp.f_pos = inode->u.umsdos_i.pos;
|
| 317 |
|
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filp.f_reada = 0;
|
| 318 |
|
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PRINTK (("pos = %d ",filp.f_pos));
|
| 319 |
|
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/* Read only the start of the entry since we don't touch */
|
| 320 |
|
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/* the name */
|
| 321 |
|
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ret = umsdos_emd_dir_read (emd_owner,&filp,(char*)&entry
|
| 322 |
|
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,UMSDOS_REC_SIZE);
|
| 323 |
|
|
if (ret == 0){
|
| 324 |
|
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if (attr->ia_valid & ATTR_UID)
|
| 325 |
|
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entry.uid = attr->ia_uid;
|
| 326 |
|
|
if (attr->ia_valid & ATTR_GID)
|
| 327 |
|
|
entry.gid = attr->ia_gid;
|
| 328 |
|
|
if (attr->ia_valid & ATTR_MODE)
|
| 329 |
|
|
entry.mode = attr->ia_mode;
|
| 330 |
|
|
if (attr->ia_valid & ATTR_ATIME)
|
| 331 |
|
|
entry.atime = attr->ia_atime;
|
| 332 |
|
|
if (attr->ia_valid & ATTR_MTIME)
|
| 333 |
|
|
entry.mtime = attr->ia_mtime;
|
| 334 |
|
|
if (attr->ia_valid & ATTR_CTIME)
|
| 335 |
|
|
entry.ctime = attr->ia_ctime;
|
| 336 |
|
|
|
| 337 |
|
|
entry.nlink = inode->i_nlink;
|
| 338 |
|
|
filp.f_pos = inode->u.umsdos_i.pos;
|
| 339 |
|
|
ret = umsdos_emd_dir_write (emd_owner,&filp,(char*)&entry
|
| 340 |
|
|
,UMSDOS_REC_SIZE);
|
| 341 |
|
|
|
| 342 |
|
|
PRINTK (("notify pos %d ret %d nlink %d "
|
| 343 |
|
|
,inode->u.umsdos_i.pos
|
| 344 |
|
|
,ret,entry.nlink));
|
| 345 |
|
|
/* #Specification: notify_change / msdos fs
|
| 346 |
|
|
notify_change operation are done only on the
|
| 347 |
|
|
EMD file. The msdos fs is not even called.
|
| 348 |
|
|
*/
|
| 349 |
|
|
}
|
| 350 |
|
|
iput (emd_owner);
|
| 351 |
|
|
}
|
| 352 |
|
|
PRINTK (("\n"));
|
| 353 |
|
|
}
|
| 354 |
|
|
}
|
| 355 |
|
|
if (ret == 0)
|
| 356 |
|
|
inode_setattr(inode, attr);
|
| 357 |
|
|
return ret;
|
| 358 |
|
|
}
|
| 359 |
|
|
|
| 360 |
|
|
/* #Specification: function name / convention
|
| 361 |
|
|
A simple convention for function name has been used in
|
| 362 |
|
|
the UMSDOS file system. First all function use the prefix
|
| 363 |
|
|
umsdos_ to avoid name clash with other part of the kernel.
|
| 364 |
|
|
|
| 365 |
|
|
And standard VFS entry point use the prefix UMSDOS (upper case)
|
| 366 |
|
|
so it's easier to tell them apart.
|
| 367 |
|
|
*/
|
| 368 |
|
|
|
| 369 |
|
|
static struct super_operations umsdos_sops = {
|
| 370 |
|
|
UMSDOS_read_inode,
|
| 371 |
|
|
UMSDOS_notify_change,
|
| 372 |
|
|
UMSDOS_write_inode,
|
| 373 |
|
|
UMSDOS_put_inode,
|
| 374 |
|
|
UMSDOS_put_super,
|
| 375 |
|
|
NULL, /* added in 0.96c */
|
| 376 |
|
|
UMSDOS_statfs,
|
| 377 |
|
|
NULL
|
| 378 |
|
|
};
|
| 379 |
|
|
|
| 380 |
|
|
/*
|
| 381 |
|
|
Read the super block of an Extended MS-DOS FS.
|
| 382 |
|
|
*/
|
| 383 |
|
|
struct super_block *UMSDOS_read_super(
|
| 384 |
|
|
struct super_block *s,
|
| 385 |
|
|
void *data,
|
| 386 |
|
|
int silent)
|
| 387 |
|
|
{
|
| 388 |
|
|
/* #Specification: mount / options
|
| 389 |
|
|
Umsdos run on top of msdos. Currently, it supports no
|
| 390 |
|
|
mount option, but happily pass all option received to
|
| 391 |
|
|
the msdos driver. I am not sure if all msdos mount option
|
| 392 |
|
|
make sense with Umsdos. Here are at least those who
|
| 393 |
|
|
are useful.
|
| 394 |
|
|
uid=
|
| 395 |
|
|
gid=
|
| 396 |
|
|
|
| 397 |
|
|
These options affect the operation of umsdos in directories
|
| 398 |
|
|
which do not have an EMD file. They behave like normal
|
| 399 |
|
|
msdos directory, with all limitation of msdos.
|
| 400 |
|
|
*/
|
| 401 |
|
|
struct super_block *sb;
|
| 402 |
|
|
MOD_INC_USE_COUNT;
|
| 403 |
|
|
sb = msdos_read_super(s,data,silent);
|
| 404 |
|
|
printk ("UMSDOS Beta 0.6 (compatibility level %d.%d, fast msdos)\n"
|
| 405 |
|
|
,UMSDOS_VERSION,UMSDOS_RELEASE);
|
| 406 |
|
|
if (sb != NULL){
|
| 407 |
|
|
MSDOS_SB(sb)->options.dotsOK = 0; /* disable hidden==dotfile */
|
| 408 |
|
|
sb->s_op = &umsdos_sops;
|
| 409 |
|
|
PRINTK (("umsdos_read_super %p\n",sb->s_mounted));
|
| 410 |
|
|
umsdos_setup_dir_inode (sb->s_mounted);
|
| 411 |
|
|
PRINTK (("End umsdos_read_super\n"));
|
| 412 |
|
|
if (s == super_blocks){
|
| 413 |
|
|
/* #Specification: pseudo root / mount
|
| 414 |
|
|
When a umsdos fs is mounted, a special handling is done
|
| 415 |
|
|
if it is the root partition. We check for the presence
|
| 416 |
|
|
of the file /linux/etc/init or /linux/etc/rc or
|
| 417 |
|
|
/linux/sbin/init. If one is there, we do a chroot("/linux").
|
| 418 |
|
|
|
| 419 |
|
|
We check both because (see init/main.c) the kernel
|
| 420 |
|
|
try to exec init at different place and if it fails
|
| 421 |
|
|
it tries /bin/sh /etc/rc. To be consistent with
|
| 422 |
|
|
init/main.c, many more test would have to be done
|
| 423 |
|
|
to locate init. Any complain ?
|
| 424 |
|
|
|
| 425 |
|
|
The chroot is done manually in init/main.c but the
|
| 426 |
|
|
info (the inode) is located at mount time and store
|
| 427 |
|
|
in a global variable (pseudo_root) which is used at
|
| 428 |
|
|
different place in the umsdos driver. There is no
|
| 429 |
|
|
need to store this variable elsewhere because it
|
| 430 |
|
|
will always be one, not one per mount.
|
| 431 |
|
|
|
| 432 |
|
|
This feature allows the installation
|
| 433 |
|
|
of a linux system within a DOS system in a subdirectory.
|
| 434 |
|
|
|
| 435 |
|
|
A user may install its linux stuff in c:\linux
|
| 436 |
|
|
avoiding any clash with existing DOS file and subdirectory.
|
| 437 |
|
|
When linux boots, it hides this fact, showing a normal
|
| 438 |
|
|
root directory with /etc /bin /tmp ...
|
| 439 |
|
|
|
| 440 |
|
|
The word "linux" is hardcoded in /usr/include/linux/umsdos_fs.h
|
| 441 |
|
|
in the macro UMSDOS_PSDROOT_NAME.
|
| 442 |
|
|
*/
|
| 443 |
|
|
|
| 444 |
|
|
struct inode *pseudo;
|
| 445 |
|
|
Printk (("Mounting root\n"));
|
| 446 |
|
|
if (umsdos_real_lookup (sb->s_mounted,UMSDOS_PSDROOT_NAME
|
| 447 |
|
|
,UMSDOS_PSDROOT_LEN,&pseudo)==0
|
| 448 |
|
|
&& S_ISDIR(pseudo->i_mode)){
|
| 449 |
|
|
struct inode *etc = NULL;
|
| 450 |
|
|
struct inode *sbin = NULL;
|
| 451 |
|
|
int pseudo_ok = 0;
|
| 452 |
|
|
Printk (("/%s is there\n",UMSDOS_PSDROOT_NAME));
|
| 453 |
|
|
if (umsdos_real_lookup (pseudo,"etc",3,&etc)==0
|
| 454 |
|
|
&& S_ISDIR(etc->i_mode)){
|
| 455 |
|
|
struct inode *init = NULL;
|
| 456 |
|
|
struct inode *rc = NULL;
|
| 457 |
|
|
Printk (("/%s/etc is there\n",UMSDOS_PSDROOT_NAME));
|
| 458 |
|
|
if ((umsdos_real_lookup (etc,"init",4,&init)==0
|
| 459 |
|
|
&& S_ISREG(init->i_mode))
|
| 460 |
|
|
|| (umsdos_real_lookup (etc,"rc",2,&rc)==0
|
| 461 |
|
|
&& S_ISREG(rc->i_mode))){
|
| 462 |
|
|
pseudo_ok = 1;
|
| 463 |
|
|
}
|
| 464 |
|
|
iput (init);
|
| 465 |
|
|
iput (rc);
|
| 466 |
|
|
}
|
| 467 |
|
|
if (!pseudo_ok
|
| 468 |
|
|
&& umsdos_real_lookup (pseudo,"sbin",4,&sbin)==0
|
| 469 |
|
|
&& S_ISDIR(sbin->i_mode)){
|
| 470 |
|
|
struct inode *init = NULL;
|
| 471 |
|
|
Printk (("/%s/sbin is there\n",UMSDOS_PSDROOT_NAME));
|
| 472 |
|
|
if (umsdos_real_lookup (sbin,"init",4,&init)==0
|
| 473 |
|
|
&& S_ISREG(init->i_mode)){
|
| 474 |
|
|
pseudo_ok = 1;
|
| 475 |
|
|
}
|
| 476 |
|
|
iput (init);
|
| 477 |
|
|
}
|
| 478 |
|
|
if (pseudo_ok){
|
| 479 |
|
|
umsdos_setup_dir_inode (pseudo);
|
| 480 |
|
|
Printk (("Activating pseudo root /%s\n",UMSDOS_PSDROOT_NAME));
|
| 481 |
|
|
pseudo_root = pseudo;
|
| 482 |
|
|
pseudo->i_count++;
|
| 483 |
|
|
pseudo = NULL;
|
| 484 |
|
|
}
|
| 485 |
|
|
iput (sbin);
|
| 486 |
|
|
iput (etc);
|
| 487 |
|
|
}
|
| 488 |
|
|
iput (pseudo);
|
| 489 |
|
|
}
|
| 490 |
|
|
} else {
|
| 491 |
|
|
MOD_DEC_USE_COUNT;
|
| 492 |
|
|
}
|
| 493 |
|
|
return sb;
|
| 494 |
|
|
}
|
| 495 |
|
|
|
| 496 |
|
|
|
| 497 |
|
|
|
| 498 |
|
|
static struct file_system_type umsdos_fs_type = {
|
| 499 |
|
|
UMSDOS_read_super, "umsdos", 1, NULL
|
| 500 |
|
|
};
|
| 501 |
|
|
|
| 502 |
|
|
int init_umsdos_fs(void)
|
| 503 |
|
|
{
|
| 504 |
|
|
return register_filesystem(&umsdos_fs_type);
|
| 505 |
|
|
}
|
| 506 |
|
|
|
| 507 |
|
|
#ifdef MODULE
|
| 508 |
|
|
int init_module(void)
|
| 509 |
|
|
{
|
| 510 |
|
|
int status;
|
| 511 |
|
|
|
| 512 |
|
|
if ((status = init_umsdos_fs()) == 0)
|
| 513 |
|
|
register_symtab(0);
|
| 514 |
|
|
return status;
|
| 515 |
|
|
}
|
| 516 |
|
|
|
| 517 |
|
|
void cleanup_module(void)
|
| 518 |
|
|
{
|
| 519 |
|
|
unregister_filesystem(&umsdos_fs_type);
|
| 520 |
|
|
}
|
| 521 |
|
|
|
| 522 |
|
|
#endif
|
| 523 |
|
|
|
