path: root/fs/umsdos/inode.c

/*
 *  linux/fs/umsdos/inode.c
 *
 *	Written 1993 by Jacques Gelinas
 *	Inspired from linux/fs/msdos/... by Werner Almesberger
 *
 */

#include <linux/module.h>

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/uaccess.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 ((KERN_DEBUG "put inode %p (%lu) owner %lu pos %lu dir %lu\n", inode, inode->i_ino
	   ,inode->u.umsdos_i.i_emd_owner, inode->u.umsdos_i.pos
	   ,inode->u.umsdos_i.i_emd_dir));
  if (inode && pseudo_root && inode == pseudo_root){
    printk (KERN_ERR "Umsdos: Oops releasing pseudo_root. Notify jacques@solucorp.qc.ca\n");
  }

#if 1
  fat_put_inode(inode);
#else  
  Printk ((KERN_WARNING "UMSDOS_put_inode: skipping ! FIXME /mn/\n"));
#endif
}


void UMSDOS_put_super(struct super_block *sb)
{
  Printk ((KERN_DEBUG "UMSDOS_put_super: entering\n"));
  msdos_put_super(sb);
  MOD_DEC_USE_COUNT;
}



/*
  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,
			struct dentry *dentry
			)	/* Will hold inode of the file, if successful */
{
  int ret;
  
  PRINTK ((KERN_DEBUG "umsdos_real_lookup /mn/: looking for %s /",dentry->d_name.name));
  dir->i_count++;  /* /mn/ what is this and why ? locking? */
  ret = msdos_lookup (dir,dentry);
  PRINTK (("/ returned %d\n", ret));
  
  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 = NULL;
    extern struct inode_operations umsdos_rdir_inode_operations;

    emd_dir = umsdos_emd_dir_lookup (inode,0);
    Printk ((KERN_DEBUG "umsdos_setup_dir_inode: umsdos_emd_dir_lookup for inode=%p returned %p\n",inode,emd_dir));

    if (emd_dir == NULL) {
      Printk ((KERN_DEBUG "umsdos_setup_dir_inode /mn/: Setting up dir_inode_ops --> eg. NOT using EMD.\n"));
      inode->i_op = &umsdos_rdir_inode_operations;
    } else {
      Printk ((KERN_DEBUG "umsdos_setup_dir_inode /mn/: Setting up rdir_inode_ops --> eg. using EMD.\n"));
      inode->i_op = &umsdos_dir_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;
    /* FIXME, I don't have a clue on this one */
    Printk ((KERN_WARNING "umsdos_set_dirinfo: /mn/ FIXME: no clue\n"));
    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 atomic_read(&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.
  */
  
  Printk ((KERN_DEBUG "Entering umsdos_patch_inode for inode=%lu\n", inode->i_ino));
  
  if (!umsdos_isinit(inode)){
    inode->u.umsdos_i.i_emd_dir = 0;
    if (S_ISREG(inode->i_mode)){
      if (inode->i_op->bmap != NULL){
        Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: seting i_op = umsdos_file_inode_operations\n"));
	inode->i_op = &umsdos_file_inode_operations;
      }else{
        Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: seting i_op = umsdos_file_inode_operations_no_bmap\n"));
	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)){
      Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: seting i_op = umsdos_symlink_inode_operations\n"));
      inode->i_op = &umsdos_symlink_inode_operations;
    }else if (S_ISCHR(inode->i_mode)){
      Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: seting i_op = chrdev_inode_operations\n"));
      inode->i_op = &chrdev_inode_operations;
    }else if (S_ISBLK(inode->i_mode)){
      Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: seting i_op = blkdev_inode_operations\n"));
      inode->i_op = &blkdev_inode_operations;
    }else if (S_ISFIFO(inode->i_mode)){
      Printk ((KERN_DEBUG "umsdos_patch_inode /mn/: uhm, init_fifo\n"));
      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()
      */
      PRINTK ((KERN_DEBUG "umsdos_patch_inode /mn/: here we go: calling umsdos_set_dirinfo (%p,%p,%lu)\n", inode, dir, f_pos));
      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.
    */
      /* FIXME, again, not a clue */
      struct inode *emd_owner;
      Printk ((KERN_WARNING "umsdos_patch_inode: /mn/ Warning: untested emd_owner thingy...\n"));
      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 ((KERN_DEBUG "UMSDOS_read_inode %p ino = %lu ",inode,inode->i_ino));
	msdos_read_inode(inode);
	PRINTK (("ino after msdos_read_inode= %lu\n",inode->i_ino));
	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 (FIXME: missing notify_change)\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.
	*/
	/* FIXME, notify_change now takes a dentry, not an
	   inode so, the emd update needs to be done here
	UMSDOS_notify_change (inode, &newattrs);
	*/
	
	/* FIXME inode->i_dirt = 0; */
}

int UMSDOS_notify_change(struct dentry *dentry, struct iattr *attr)
{
  int ret = 0;
  struct inode *inode = dentry->d_inode;
  
  Printk ((KERN_ERR "UMSDOS_notify_change: /mn/ completly untested\n"));
  
  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 == iget(inode->i_sb,UMSDOS_ROOT_INO)){
      /* #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;
	loff_t offs;
	offs = 0;
	filp.f_pos = inode->u.umsdos_i.pos;
	filp.f_reada = 0;
	Printk (("pos = %Lu ", 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, &offs);
	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;
	  offs = 0; /* FIXME */
	  ret = umsdos_emd_dir_write (emd_owner, &filp, (char*)&entry, UMSDOS_REC_SIZE, &offs);
	  
	  Printk (("notify pos %lu 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.
   N.B. (FIXME) PTW, the order and contents of this struct changed
*/

static struct super_operations umsdos_sops = {
    UMSDOS_read_inode,		/* read_inode */
    UMSDOS_write_inode,		/* write_inode */
    UMSDOS_put_inode,		/* put_inode */
    NULL,			/* delete_inode */ 
    UMSDOS_notify_change,	/* notify_change */
    UMSDOS_put_super,		/* put_super */
    NULL,			/* write_super */
    fat_statfs,			/* statfs */
    NULL			/* remount_fs*/
};

/*
  Read the super block of an Extended MS-DOS FS.
*/
struct super_block *UMSDOS_read_super(
				      struct super_block *sb,
				      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 *res;
    struct inode *pseudo=NULL;
    Printk ((KERN_DEBUG "UMSDOS /mn/: starting UMSDOS_read_super\n"));
    MOD_INC_USE_COUNT;
    PRINTK ((KERN_DEBUG "UMSDOS /mn/: sb = %p\n",sb));
    res = msdos_read_super(sb,data,silent);
    PRINTK ((KERN_DEBUG "UMSDOS /mn/: res = %p\n",res));
    printk (KERN_INFO "UMSDOS dentry-WIP-Beta 0.82-1 (compatibility level %d.%d, fast msdos)\n", UMSDOS_VERSION, UMSDOS_RELEASE);
	  
    if (res == NULL) { MOD_DEC_USE_COUNT; return NULL; }

    MSDOS_SB(res)->options.dotsOK = 0;  /* disable hidden==dotfile */
    res->s_op = &umsdos_sops;
    Printk ((KERN_DEBUG "umsdos /mn/: here goes the iget ROOT_INO\n"));

    pseudo = iget(res,UMSDOS_ROOT_INO); 		
    Printk ((KERN_DEBUG "umsdos_read_super %p\n",pseudo));

    umsdos_setup_dir_inode (pseudo);
    
#if 0	/* disabled /mn/ test FIXME */    

    /* if (s == super_blocks){ FIXME, super_blocks no longer exported */
    if(pseudo) {
      /* #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 dentry *root, *etc, *etc_rc, *init, *sbin; /* FIXME */

      root = creat_dentry (UMSDOS_PSDROOT_NAME, strlen(UMSDOS_PSDROOT_NAME), NULL);
      sbin = creat_dentry ("sbin", 4, NULL);
      
      Printk ((KERN_DEBUG "Mounting root\n"));
      if (umsdos_real_lookup (pseudo,root)==0
          && (root->d_inode != NULL)
	  && S_ISDIR(root->d_inode->i_mode)){
	
	int pseudo_ok = 0;
	Printk ((KERN_DEBUG "/%s is there\n",UMSDOS_PSDROOT_NAME));
	etc = creat_dentry ("etc", 3, NULL);
	
	
	/* if (umsdos_real_lookup (pseudo,"etc",3,etc)==0 */
	if(umsdos_real_lookup(pseudo, etc) == 0
	   && S_ISDIR(etc->d_inode->i_mode)){

	    Printk ((KERN_DEBUG "/%s/etc is there\n",UMSDOS_PSDROOT_NAME));
	    
	    init = creat_dentry ("init", 4, NULL);
	    etc_rc = creat_dentry ("rc", 2, NULL);
	  
	    /* if ((umsdos_real_lookup (etc,"init",4,init)==0*/
	    if((umsdos_real_lookup(pseudo, init) == 0
		&& S_ISREG(init->d_inode->i_mode))
	       /*	|| (umsdos_real_lookup (etc,"rc",2,&rc)==0*/
	       || (umsdos_real_lookup(pseudo, etc_rc) == 0
		   && S_ISREG(etc_rc->d_inode->i_mode))){
		pseudo_ok = 1;
	  }
	    /* FIXME !!!!!! */
	    /* iput(init); */
	    /* iput(rc); */
	}
	if (!pseudo_ok
	/* && umsdos_real_lookup (pseudo, "sbin", 4, sbin)==0*/
	    && umsdos_real_lookup(pseudo, sbin) == 0
	    && S_ISDIR(sbin->d_inode->i_mode)){
	  
	  Printk ((KERN_DEBUG "/%s/sbin is there\n",UMSDOS_PSDROOT_NAME));
	  /* if (umsdos_real_lookup (sbin,"init",4,init)==0 */
	  if(umsdos_real_lookup(pseudo, init) == 0	
	     && S_ISREG(init->d_inode->i_mode)){
	    pseudo_ok = 1;
	  }
	  /* FIXME !!! 
	     iput (init); */
	}
	if (pseudo_ok){
	  umsdos_setup_dir_inode (pseudo);
	  Printk ((KERN_INFO "Activating pseudo root /%s\n",UMSDOS_PSDROOT_NAME));
	  pseudo_root = pseudo;
	  pseudo->i_count++;
	  pseudo = NULL;
	}
	/* FIXME 
	
	iput (sbin);
	iput (etc);
	*/
      }
      
      Printk ((KERN_WARNING "umsdos_read_super /mn/: Pseudo should be iput-ed here...\n"));

      iput (pseudo); /* FIXME */
    }

#endif /* disabled */

    PRINTK ((KERN_DEBUG "umsdos_read_super /mn/: returning %p\n",res));
    return res;
}



static struct file_system_type umsdos_fs_type = {
  "umsdos",
  FS_REQUIRES_DEV,
  UMSDOS_read_super,
  NULL
};

__initfunc(int init_umsdos_fs(void))
{
  return register_filesystem(&umsdos_fs_type);
}

#ifdef MODULE
EXPORT_NO_SYMBOLS;

int init_module(void)
{
  return init_umsdos_fs();
}

void cleanup_module(void)
{
  unregister_filesystem(&umsdos_fs_type);
}

#endif