/*
* linux/fs/umsdos/inode.c
*
* Written 1993 by Jacques Gelinas
* Inspired from linux/fs/msdos/... by Werner Almesberger
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/segment.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/umsdos_fs.h>
struct inode *pseudo_root=NULL; /* Useful to simulate the pseudo DOS */
/* directory. See UMSDOS_readdir_x() */
/* #Specification: convention / PRINTK Printk and printk
Here is the convention for the use of printk inside fs/umsdos
printk carry important message (error or status).
Printk is for debugging (it is a macro defined at the beginning of
most source.
PRINTK is a nulled Printk macro.
This convention makes the source easier to read, and Printk easier
to shut off.
*/
#define PRINTK(x)
#define Printk(x) printk x
void UMSDOS_put_inode(struct inode *inode)
{
PRINTK (("put inode %x owner %x pos %d dir %x\n",inode
,inode->u.umsdos_i.i_emd_owner,inode->u.umsdos_i.pos
,inode->u.umsdos_i.i_emd_dir));
if (inode != NULL && inode == pseudo_root){
printk ("Umsdos: Oops releasing pseudo_root. Notify jacques@solucorp.qc.ca\n");
}
fat_put_inode(inode);
}
void UMSDOS_put_super(struct super_block *sb)
{
msdos_put_super(sb);
MOD_DEC_USE_COUNT;
}
void UMSDOS_statfs(struct super_block *sb,struct statfs *buf, int bufsiz)
{
fat_statfs(sb,buf,bufsiz);
}
/*
Call msdos_lookup, but set back the original msdos function table.
Return 0 if ok, or a negative error code if not.
*/
int umsdos_real_lookup (
struct inode *dir,
const char *name,
int len,
struct inode **result) /* Will hold inode of the file, if successful */
{
int ret;
dir->i_count++;
ret = msdos_lookup (dir,name,len,result);
return ret;
}
/*
Complete the setup of an directory inode.
First, it completes the function pointers, then
it locates the EMD file. If the EMD is there, then plug the
umsdos function table. If not, use the msdos one.
*/
void umsdos_setup_dir_inode (struct inode *inode)
{
inode->u.umsdos_i.i_emd_dir = 0;
{
struct inode *emd_dir = umsdos_emd_dir_lookup (inode,0);
extern struct inode_operations umsdos_rdir_inode_operations;
inode->i_op = emd_dir != NULL
? &umsdos_dir_inode_operations
: &umsdos_rdir_inode_operations;
iput (emd_dir);
}
}
/*
Add some info into an inode so it can find its owner quickly
*/
void umsdos_set_dirinfo(
struct inode *inode,
struct inode *dir,
off_t f_pos)
{
struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
inode->u.umsdos_i.i_dir_owner = dir->i_ino;
inode->u.umsdos_i.i_emd_owner = emd_owner->i_ino;
iput (emd_owner);
inode->u.umsdos_i.pos = f_pos;
}
/*
Tells if an Umsdos inode has been "patched" once.
Return != 0 if so.
*/
int umsdos_isinit (struct inode *inode)
{
#if 1
return inode->u.umsdos_i.i_emd_owner != 0;
#elif 0
return inode->i_atime != 0;
#else
return inode->i_count > 1;
#endif
}
/*
Connect the proper tables in the inode and add some info.
*/
void umsdos_patch_inode (
struct inode *inode,
struct inode *dir, /* May be NULL */
off_t f_pos)
{
/*
This function is called very early to setup the inode, somewhat
too early (called by UMSDOS_read_inode). At this point, we can't
do to much, such as lookup up EMD files and so on. This causes
confusion in the kernel. This is why some initialisation
will be done when dir != NULL only.
UMSDOS do run piggy back on top of msdos fs. It looks like something
is missing in the VFS to accommodate stacked fs. Still unclear what
(quite honestly).
Well, maybe one! A new entry "may_unmount" which would allow
the stacked fs to allocate some inode permanently and release
them at the end. Doing that now introduce a problem. unmount
always fail because some inodes are in use.
*/
if (!umsdos_isinit(inode)){
inode->u.umsdos_i.i_emd_dir = 0;
if (S_ISREG(inode->i_mode)){
if (inode->i_op->bmap != NULL){
inode->i_op = &umsdos_file_inode_operations;
}else{
inode->i_op = &umsdos_file_inode_operations_no_bmap;
}
}else if (S_ISDIR(inode->i_mode)){
if (dir != NULL){
umsdos_setup_dir_inode(inode);
}
}else if (S_ISLNK(inode->i_mode)){
inode->i_op = &umsdos_symlink_inode_operations;
}else if (S_ISCHR(inode->i_mode)){
inode->i_op = &chrdev_inode_operations;
}else if (S_ISBLK(inode->i_mode)){
inode->i_op = &blkdev_inode_operations;
}else if (S_ISFIFO(inode->i_mode)){
init_fifo(inode);
}
if (dir != NULL){
/* #Specification: inode / umsdos info
The first time an inode is seen (inode->i_count == 1),
the inode number of the EMD file which control this inode
is tagged to this inode. It allows operation such
as notify_change to be handled.
*/
/*
This is done last because it also control the
status of umsdos_isinit()
*/
umsdos_set_dirinfo (inode,dir,f_pos);
}
}else if (dir != NULL){
/*
Test to see if the info is maintained.
This should be removed when the file system will be proven.
*/
struct inode *emd_owner = umsdos_emd_dir_lookup(dir,1);
iput (emd_owner);
if (emd_owner->i_ino != inode->u.umsdos_i.i_emd_owner){
printk ("UMSDOS: *** EMD_OWNER ??? *** ino = %ld %ld <> %ld "
,inode->i_ino,emd_owner->i_ino,inode->u.umsdos_i.i_emd_owner);
}
}
}
/*
Get the inode of the directory which owns this inode.
Return 0 if ok, -EIO if error.
*/
int umsdos_get_dirowner(
struct inode *inode,
struct inode **result) /* Hold NULL if any error */
/* else, the inode of the directory */
{
int ret = -EIO;
unsigned long ino = inode->u.umsdos_i.i_dir_owner;
*result = NULL;
if (ino == 0){
printk ("UMSDOS: umsdos_get_dirowner ino == 0\n");
}else{
struct inode *dir = *result = iget(inode->i_sb,ino);
if (dir != NULL){
umsdos_patch_inode (dir,NULL,0);
ret = 0;
}
}
return ret;
}
/*
Load an inode from disk.
*/
void UMSDOS_read_inode(struct inode *inode)
{
PRINTK (("read inode %x ino = %d ",inode,inode->i_ino));
msdos_read_inode(inode);
PRINTK (("ino = %d %d\n",inode->i_ino,inode->i_count));
if (S_ISDIR(inode->i_mode)
&& (inode->u.umsdos_i.u.dir_info.creating != 0
|| inode->u.umsdos_i.u.dir_info.looking != 0
|| waitqueue_active(&inode->u.umsdos_i.u.dir_info.p))){
Printk (("read inode %d %d %p\n"
,inode->u.umsdos_i.u.dir_info.creating
,inode->u.umsdos_i.u.dir_info.looking
,inode->u.umsdos_i.u.dir_info.p));
}
/* #Specification: Inode / post initialisation
To completely initialise an inode, we need access to the owner
directory, so we can locate more info in the EMD file. This is
not available the first time the inode is access, we use
a value in the inode to tell if it has been finally initialised.
At first, we have tried testing i_count but it was causing
problem. It is possible that two or more process use the
newly accessed inode. While the first one block during
the initialisation (probably while reading the EMD file), the
others believe all is well because i_count > 1. They go banana
with a broken inode. See umsdos_lookup_patch and umsdos_patch_inode.
*/
umsdos_patch_inode(inode,NULL,0);
}
/*
Update the disk with the inode content
*/
void UMSDOS_write_inode(struct inode *inode)
{
struct iattr newattrs;
PRINTK (("UMSDOS_write_inode emd %d\n",inode->u.umsdos_i.i_emd_owner));
fat_write_inode(inode);
newattrs.ia_mtime = inode->i_mtime;
newattrs.ia_atime = inode->i_atime;
newattrs.ia_ctime = inode->i_ctime;
newattrs.ia_valid = ATTR_MTIME | ATTR_ATIME | ATTR_CTIME;
/*
UMSDOS_notify_change is convenient to call here
to update the EMD entry associated with this inode.
But it has the side effect to re"dirt" the inode.
*/
UMSDOS_notify_change (inode, &newattrs);
inode->i_dirt = 0;
}
int UMSDOS_notify_change(struct inode *inode, struct iattr *attr)
{
int ret = 0;
if ((ret = inode_change_ok(inode, attr)) != 0)
return ret;
if (inode->i_nlink > 0){
/* #Specification: notify_change / i_nlink > 0
notify change is only done for inode with nlink > 0. An inode
with nlink == 0 is no longer associated with any entry in
the EMD file, so there is nothing to update.
*/
unsigned long i_emd_owner = inode->u.umsdos_i.i_emd_owner;
if (inode == inode->i_sb->s_mounted){
/* #Specification: root inode / attributes
I don't know yet how this should work. Normally
the attributes (permissions bits, owner, times) of
a directory are stored in the EMD file of its parent.
One thing we could do is store the attributes of the root
inode in its own EMD file. A simple entry named "." could
be used for this special case. It would be read once
when the file system is mounted and update in
UMSDOS_notify_change() (right here).
I am not sure of the behavior of the root inode for
a real UNIX file system. For now, this is a nop.
*/
}else if (i_emd_owner != 0xffffffff && i_emd_owner != 0){
/* This inode is not a EMD file nor an inode used internally
by MSDOS, so we can update its status.
See emd.c
*/
struct inode *emd_owner = iget (inode->i_sb,i_emd_owner);
PRINTK (("notify change %p ",inode));
if (emd_owner == NULL){
printk ("UMSDOS: emd_owner = NULL ???");
ret = -EPERM;
}else{
struct file filp;
struct umsdos_dirent entry;
filp.f_pos = inode->u.umsdos_i.pos;
filp.f_reada = 0;
PRINTK (("pos = %d ",filp.f_pos));
/* Read only the start of the entry since we don't touch */
/* the name */
ret = umsdos_emd_dir_read (emd_owner,&filp,(char*)&entry
,UMSDOS_REC_SIZE);
if (ret == 0){
if (attr->ia_valid & ATTR_UID)
entry.uid = attr->ia_uid;
if (attr->ia_valid & ATTR_GID)
entry.gid = attr->ia_gid;
if (attr->ia_valid & ATTR_MODE)
entry.mode = attr->ia_mode;
if (attr->ia_valid & ATTR_ATIME)
entry.atime = attr->ia_atime;
if (attr->ia_valid & ATTR_MTIME)
entry.mtime = attr->ia_mtime;
if (attr->ia_valid & ATTR_CTIME)
entry.ctime = attr->ia_ctime;
entry.nlink = inode->i_nlink;
filp.f_pos = inode->u.umsdos_i.pos;
ret = umsdos_emd_dir_write (emd_owner,&filp,(char*)&entry
,UMSDOS_REC_SIZE);
PRINTK (("notify pos %d ret %d nlink %d "
,inode->u.umsdos_i.pos
,ret,entry.nlink));
/* #Specification: notify_change / msdos fs
notify_change operation are done only on the
EMD file. The msdos fs is not even called.
*/
}
iput (emd_owner);
}
PRINTK (("\n"));
}
}
if (ret == 0)
inode_setattr(inode, attr);
return ret;
}
/* #Specification: function name / convention
A simple convention for function name has been used in
the UMSDOS file system. First all function use the prefix
umsdos_ to avoid name clash with other part of the kernel.
And standard VFS entry point use the prefix UMSDOS (upper case)
so it's easier to tell them apart.
*/
static struct super_operations umsdos_sops = {
UMSDOS_read_inode,
UMSDOS_notify_change,
UMSDOS_write_inode,
UMSDOS_put_inode,
UMSDOS_put_super,
NULL, /* added in 0.96c */
UMSDOS_statfs,
NULL
};
/*
Read the super block of an Extended MS-DOS FS.
*/
struct super_block *UMSDOS_read_super(
struct super_block *s,
void *data,
int silent)
{
/* #Specification: mount / options
Umsdos run on top of msdos. Currently, it supports no
mount option, but happily pass all option received to
the msdos driver. I am not sure if all msdos mount option
make sense with Umsdos. Here are at least those who
are useful.
uid=
gid=
These options affect the operation of umsdos in directories
which do not have an EMD file. They behave like normal
msdos directory, with all limitation of msdos.
*/
struct super_block *sb;
MOD_INC_USE_COUNT;
sb = msdos_read_super(s,data,silent);
printk ("UMSDOS Beta 0.6 (compatibility level %d.%d, fast msdos)\n"
,UMSDOS_VERSION,UMSDOS_RELEASE);
if (sb != NULL){
MSDOS_SB(sb)->options.dotsOK = 0; /* disable hidden==dotfile */
sb->s_op = &umsdos_sops;
PRINTK (("umsdos_read_super %p\n",sb->s_mounted));
umsdos_setup_dir_inode (sb->s_mounted);
PRINTK (("End umsdos_read_super\n"));
if (s == super_blocks){
/* #Specification: pseudo root / mount
When a umsdos fs is mounted, a special handling is done
if it is the root partition. We check for the presence
of the file /linux/etc/init or /linux/etc/rc or
/linux/sbin/init. If one is there, we do a chroot("/linux").
We check both because (see init/main.c) the kernel
try to exec init at different place and if it fails
it tries /bin/sh /etc/rc. To be consistent with
init/main.c, many more test would have to be done
to locate init. Any complain ?
The chroot is done manually in init/main.c but the
info (the inode) is located at mount time and store
in a global variable (pseudo_root) which is used at
different place in the umsdos driver. There is no
need to store this variable elsewhere because it
will always be one, not one per mount.
This feature allows the installation
of a linux system within a DOS system in a subdirectory.
A user may install its linux stuff in c:\linux
avoiding any clash with existing DOS file and subdirectory.
When linux boots, it hides this fact, showing a normal
root directory with /etc /bin /tmp ...
The word "linux" is hardcoded in /usr/include/linux/umsdos_fs.h
in the macro UMSDOS_PSDROOT_NAME.
*/
struct inode *pseudo;
Printk (("Mounting root\n"));
if (umsdos_real_lookup (sb->s_mounted,UMSDOS_PSDROOT_NAME
,UMSDOS_PSDROOT_LEN,&pseudo)==0
&& S_ISDIR(pseudo->i_mode)){
struct inode *etc = NULL;
struct inode *sbin = NULL;
int pseudo_ok = 0;
Printk (("/%s is there\n",UMSDOS_PSDROOT_NAME));
if (umsdos_real_lookup (pseudo,"etc",3,&etc)==0
&& S_ISDIR(etc->i_mode)){
struct inode *init = NULL;
struct inode *rc = NULL;
Printk (("/%s/etc is there\n",UMSDOS_PSDROOT_NAME));
if ((umsdos_real_lookup (etc,"init",4,&init)==0
&& S_ISREG(init->i_mode))
|| (umsdos_real_lookup (etc,"rc",2,&rc)==0
&& S_ISREG(rc->i_mode))){
pseudo_ok = 1;
}
iput (init);
iput (rc);
}
if (!pseudo_ok
&& umsdos_real_lookup (pseudo,"sbin",4,&sbin)==0
&& S_ISDIR(sbin->i_mode)){
struct inode *init = NULL;
Printk (("/%s/sbin is there\n",UMSDOS_PSDROOT_NAME));
if (umsdos_real_lookup (sbin,"init",4,&init)==0
&& S_ISREG(init->i_mode)){
pseudo_ok = 1;
}
iput (init);
}
if (pseudo_ok){
umsdos_setup_dir_inode (pseudo);
Printk (("Activating pseudo root /%s\n",UMSDOS_PSDROOT_NAME));
pseudo_root = pseudo;
pseudo->i_count++;
pseudo = NULL;
}
iput (sbin);
iput (etc);
}
iput (pseudo);
}
} else {
MOD_DEC_USE_COUNT;
}
return sb;
}
static struct file_system_type umsdos_fs_type = {
UMSDOS_read_super, "umsdos", 1, NULL
};
int init_umsdos_fs(void)
{
return register_filesystem(&umsdos_fs_type);
}
#ifdef MODULE
int init_module(void)
{
int status;
if ((status = init_umsdos_fs()) == 0)
register_symtab(0);
return status;
}
void cleanup_module(void)
{
unregister_filesystem(&umsdos_fs_type);
}
#endif
