fs.c

讲述linux的初始化过程

/*
 *  fs.c
 *  NTFS driver for Linux 2.3.x
 *
 *  Copyright (C) 1995-1997, 1999 Martin von L鰓is
 *  Copyright (C) 1996 Richard Russon
 *  Copyright (C) 1996-1997 R間is Duchesne
 *  Copyright (C) 2000, Anton Altaparmakov
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef NTFS_IN_LINUX_KERNEL
#include <linux/config.h>
#endif

#include "ntfstypes.h"
#include "struct.h"
#include "util.h"
#include "inode.h"
#include "super.h"
#include "dir.h"
#include "support.h"
#include "macros.h"
#include "sysctl.h"
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/nls.h>
#include <linux/locks.h>
#include <linux/init.h>
#include <linux/smp_lock.h>

/* Forward declarations */
static struct inode_operations ntfs_dir_inode_operations;
static struct file_operations ntfs_dir_operations;

#define ITEM_SIZE 2040

/* io functions to user space */
static void ntfs_putuser(ntfs_io* dest,void *src,ntfs_size_t len)
{
	copy_to_user(dest->param,src,len);
	dest->param+=len;
}

#ifdef CONFIG_NTFS_RW
struct ntfs_getuser_update_vm_s{
	const char *user;
	struct inode *ino;
	loff_t off;
};

static void ntfs_getuser_update_vm (void *dest, ntfs_io *src, ntfs_size_t len)
{
	struct ntfs_getuser_update_vm_s *p = src->param;
	copy_from_user (dest, p->user, len);
	p->user += len;
	p->off += len;
}
#endif

static ssize_t
ntfs_read(struct file * filp, char *buf, size_t count, loff_t *off)
{
	int error;
	ntfs_io io;
	ntfs_inode *ino=NTFS_LINO2NINO(filp->f_dentry->d_inode);

	/* inode is not properly initialized */
	if(!ino)return -EINVAL;
	ntfs_debug(DEBUG_OTHER, "ntfs_read %x,%x,%x ->",
		   (unsigned)ino->i_number,(unsigned)*off,(unsigned)count);
	/* inode has no unnamed data attribute */
	if(!ntfs_find_attr(ino,ino->vol->at_data,NULL))
		return -EINVAL;
	
	/* read the data */
	io.fn_put=ntfs_putuser;
	io.fn_get=0;
	io.param=buf;
	io.size=count;
	error=ntfs_read_attr(ino,ino->vol->at_data,NULL,*off,&io);
	if(error && !io.size)return -error;
	
	*off+=io.size;
	return io.size;
}

#ifdef CONFIG_NTFS_RW
static ssize_t
ntfs_write(struct file *filp,const char* buf,size_t count,loff_t *pos)
{
	int ret;
	ntfs_io io;
	struct inode *inode = filp->f_dentry->d_inode;
	ntfs_inode *ino = NTFS_LINO2NINO(inode);
	struct ntfs_getuser_update_vm_s param;

	if (!ino)
		return -EINVAL;
	ntfs_debug (DEBUG_LINUX, "ntfs_write %x,%x,%x ->\n",
	       (unsigned)ino->i_number, (unsigned)*pos, (unsigned)count);
	/* Allows to lock fs ro at any time */
	if (inode->i_sb->s_flags & MS_RDONLY)
		return -ENOSPC;
	if (!ntfs_find_attr(ino,ino->vol->at_data,NULL))
		return -EINVAL;

	/* Evaluating O_APPEND is the file system's job... */
	if (filp->f_flags & O_APPEND)
		*pos = inode->i_size;
	param.user = buf;
	param.ino = inode;
	param.off = *pos;
	io.fn_put = 0;
	io.fn_get = ntfs_getuser_update_vm;
	io.param = &param;
	io.size = count;
	ret = ntfs_write_attr (ino, ino->vol->at_data, NULL, *pos, &io);
	ntfs_debug (DEBUG_LINUX, "write -> %x\n", ret);
	if(ret<0)
		return -EINVAL;

	*pos += io.size;
	if (*pos > inode->i_size)
		inode->i_size = *pos;
	mark_inode_dirty (filp->f_dentry->d_inode);
	return io.size;
}
#endif

struct ntfs_filldir{
	struct inode *dir;
	filldir_t filldir;
	unsigned int type;
	ntfs_u32 ph,pl;
	void *dirent;
	char *name;
	int namelen;
};
	
static int ntfs_printcb(ntfs_u8 *entry,void *param)
{
	struct ntfs_filldir* nf=param;
	int flags=NTFS_GETU8(entry+0x51);
	int show_hidden=0;
	int length=NTFS_GETU8(entry+0x50);
	int inum=NTFS_GETU32(entry);
	int error;
#ifdef NTFS_NGT_NT_DOES_LOWER
	int i,to_lower=0;
#endif
	switch(nf->type){
	case ngt_dos:
		/* Don't display long names */
		if((flags & 2)==0)
			return 0;
		break;
	case ngt_nt:
		/* Don't display short-only names */
		switch(flags&3){
		case 2: return 0;
#ifdef NTFS_NGT_NT_DOES_LOWER
		case 3: to_lower=1;
#endif
		}
		break;
	case ngt_posix:
		break;
	case ngt_full:
		show_hidden=1;
		break;
	}
	if(!show_hidden && ((NTFS_GETU8(entry+0x48) & 2)==2)){
		ntfs_debug(DEBUG_OTHER,"Skipping hidden file\n");
		return 0;
	}
	nf->name=0;
	if(ntfs_encodeuni(NTFS_INO2VOL(nf->dir),(ntfs_u16*)(entry+0x52),
			  length,&nf->name,&nf->namelen)){
		ntfs_debug(DEBUG_OTHER,"Skipping unrepresentable file\n");
		if(nf->name)ntfs_free(nf->name);
		return 0;
	}
	/* Do not return ".", as this is faked */
	if(length==1 && *nf->name=='.')
		return 0;
#ifdef NTFS_NGT_NT_DOES_LOWER
	if(to_lower)
		for(i=0;i<nf->namelen;i++)
			/* This supports ASCII only. Since only DOS-only
			   names get converted, and since those are restricted
			   to ASCII, this should be correct */
			if(nf->name[i]>='A' && nf->name[i]<='Z')
				nf->name[i]+='a'-'A';
#endif
	nf->name[nf->namelen]=0;
	ntfs_debug(DEBUG_OTHER, "readdir got %s,len %d\n",nf->name,nf->namelen);
	/* filldir expects an off_t rather than an loff_t.
	   Hope we don't have more than 65535 index records */
	error=nf->filldir(nf->dirent,nf->name,nf->namelen,
			(nf->ph<<16)|nf->pl,inum,DT_UNKNOWN);
	ntfs_free(nf->name);
	/* Linux filldir errors are negative, other errors positive */
	return error;
}

/* readdir returns '..', then '.', then the directory entries in sequence
   As the root directory contains a entry for itself, '.' is not emulated
   for the root directory */
static int ntfs_readdir(struct file* filp, void *dirent, filldir_t filldir)
{
	struct ntfs_filldir cb;
	int error;
	struct inode *dir=filp->f_dentry->d_inode;

	ntfs_debug(DEBUG_OTHER, "ntfs_readdir ino %x mode %x\n",
	       (unsigned)dir->i_ino,(unsigned int)dir->i_mode);

	ntfs_debug(DEBUG_OTHER, "readdir: Looking for file %x dircount %d\n",
	       (unsigned)filp->f_pos,atomic_read(&dir->i_count));
	cb.pl=filp->f_pos & 0xFFFF;
	cb.ph=filp->f_pos >> 16;
	/* end of directory */
	if(cb.ph==0xFFFF){
		/* FIXME: Maybe we can return those with the previous call */
		switch(cb.pl){
		case 0: filldir(dirent,".",1,filp->f_pos,dir->i_ino,DT_DIR);
			filp->f_pos=0xFFFF0001;
			return 0;
			/* FIXME: parent directory */
		case 1: filldir(dirent,"..",2,filp->f_pos,0,DT_DIR);
			filp->f_pos=0xFFFF0002;
			return 0;
		}
		ntfs_debug(DEBUG_OTHER, "readdir: EOD\n");
		return 0;
	}
	cb.dir=dir;
	cb.filldir=filldir;
	cb.dirent=dirent;
	cb.type=NTFS_INO2VOL(dir)->ngt;
	do{
		ntfs_debug(DEBUG_OTHER,"looking for next file\n");
		error=ntfs_getdir_unsorted(NTFS_LINO2NINO(dir),&cb.ph,&cb.pl,
				   ntfs_printcb,&cb);
	}while(!error && cb.ph!=0xFFFFFFFF);
	filp->f_pos=(cb.ph<<16)|cb.pl;
	ntfs_debug(DEBUG_OTHER, "new position %x\n",(unsigned)filp->f_pos);
        /* -EINVAL is on user buffer full. This is not considered 
	   as an error by sys_getdents */
	if(error<0) 
		error=0;
	/* Otherwise (device error, inconsistent data), switch the sign */
	return -error;
}

/* Copied from vfat driver */
static int simple_getbool(char *s, int *setval)
{
	if (s) {
		if (!strcmp(s,"1") || !strcmp(s,"yes") || !strcmp(s,"true")) {
			*setval = 1;
		} else if (!strcmp(s,"0") || !strcmp(s,"no") || !strcmp(s,"false")) {
			*setval = 0;
		} else {
			return 0;
		}
	} else {
		*setval = 1;
	}
	return 1;
}

/* Parse the (re)mount options */
static int parse_options(ntfs_volume* vol,char *opt)
{
	char *value;

	vol->uid=vol->gid=0;
	vol->umask=0077;
	vol->ngt=ngt_nt;
	vol->nls_map=0;
	vol->nct=0;
	if(!opt)goto done;

	for(opt = strtok(opt,",");opt;opt=strtok(NULL,","))
	{
		if ((value = strchr(opt, '=')) != NULL)
			*value++='\0';
		if(strcmp(opt,"uid")==0)
		{
			if(!value || !*value)goto needs_arg;
			vol->uid=simple_strtoul(value,&value,0);
			if(*value){
				printk(KERN_ERR "NTFS: uid invalid argument\n");
				return 0;
			}
		}else if(strcmp(opt, "gid") == 0)
		{
			if(!value || !*value)goto needs_arg;
			vol->gid=simple_strtoul(value,&value,0);
			if(*value){
				printk(KERN_ERR "gid invalid argument\n");
				return 0;
			}
		}else if(strcmp(opt, "umask") == 0)
		{
			if(!value || !*value)goto needs_arg;
			vol->umask=simple_strtoul(value,&value,0);
			if(*value){
				printk(KERN_ERR "umask invalid argument\n");
				return 0;
			}
		}else if(strcmp(opt, "iocharset") == 0){
			if(!value || !*value)goto needs_arg;
			vol->nls_map=load_nls(value);
			vol->nct |= nct_map;
			if(!vol->nls_map){
				printk(KERN_ERR "NTFS: charset not found");
				return 0;
			}
		}else if(strcmp(opt, "posix") == 0){
			int val;
			if(!value || !*value)goto needs_arg;
			if(!simple_getbool(value,&val))
				goto needs_bool;
			vol->ngt=val?ngt_posix:ngt_nt;
		}else if(strcmp(opt,"utf8") == 0){
			int val=0;
			if(!value || !*value)
				val=1;
			else if(!simple_getbool(value,&val))
				goto needs_bool;
			if(val)
				vol->nct|=nct_utf8;
		}else if(strcmp(opt,"uni_xlate") == 0){
			int val=0;
			/* no argument: uni_vfat.
			   boolean argument: uni_vfat.
			   "2": uni.
			*/
			if(!value || !*value)
				val=1;
			else if(strcmp(value,"2")==0)
				vol->nct |= nct_uni_xlate;
			else if(!simple_getbool(value,&val))
				goto needs_bool;
			if(val)
				vol->nct |= nct_uni_xlate_vfat | nct_uni_xlate;
		}else{
			printk(KERN_ERR "NTFS: unkown option '%s'\n", opt);
			return 0;
		}
	}
	if(vol->nct & nct_utf8 & (nct_map | nct_uni_xlate)){
		printk(KERN_ERR "utf8 cannot be combined with iocharset or uni_xlate\n");
		return 0;
	}
 done:
	if((vol->nct & (nct_uni_xlate | nct_map | nct_utf8))==0)
		/* default to UTF-8 */
		vol->nct=nct_utf8;
	if(!vol->nls_map){
		vol->nls_map=load_nls_default();
		if (vol->nls_map)
			vol->nct=nct_map | (vol->nct&nct_uni_xlate);
	}
	return 1;

 needs_arg:
	printk(KERN_ERR "NTFS: %s needs an argument",opt);
	return 0;
 needs_bool:
	printk(KERN_ERR "NTFS: %s needs boolean argument",opt);
	return 0;
}
			
static struct dentry *ntfs_lookup(struct inode *dir, struct dentry *d)
{
	struct inode *res=0;
	char *item=0;
	ntfs_iterate_s walk;
	int error;
	ntfs_debug(DEBUG_NAME1, "Looking up %s in %x\n",d->d_name.name,
		   (unsigned)dir->i_ino);
	/* convert to wide string */
	error=ntfs_decodeuni(NTFS_INO2VOL(dir),(char*)d->d_name.name,
			     d->d_name.len,&walk.name,&walk.namelen);
	if(error)
		return ERR_PTR(-error);
	item=ntfs_malloc(ITEM_SIZE);
	if( !item )
		return ERR_PTR(-ENOMEM);
	/* ntfs_getdir will place the directory entry into item,
	   and the first long long is the MFT record number */
	walk.type=BY_NAME;
	walk.dir=NTFS_LINO2NINO(dir);
	walk.result=item;
	if(ntfs_getdir_byname(&walk))
	{
		res=iget(dir->i_sb,NTFS_GETU32(item));
	}
	d_add(d,res);
	ntfs_free(item);
	ntfs_free(walk.name);
	/* Always return success, the dcache will handle negative entries. */
	return NULL;
}

static struct file_operations ntfs_file_operations_nommap = {
	read:		ntfs_read,
#ifdef CONFIG_NTFS_RW
	write:		ntfs_write,
#endif
};

static struct inode_operations ntfs_inode_operations_nobmap;

#ifdef CONFIG_NTFS_RW
static int
ntfs_create(struct inode* dir,struct dentry *d,int mode)
{
	struct inode *r=0;
	ntfs_inode *ino=0;
	ntfs_volume *vol;
	int error=0;
	ntfs_attribute *si;

	r=new_inode(dir->i_sb);
	if(!r){
		error=ENOMEM;
		goto fail;
	}

	ntfs_debug(DEBUG_OTHER, "ntfs_create %s\n",d->d_name.name);
	vol=NTFS_INO2VOL(dir);
#ifdef NTFS_IN_LINUX_KERNEL
	ino=NTFS_LINO2NINO(r);
#else
	ino=ntfs_malloc(sizeof(ntfs_inode));
	if(!ino){
		error=ENOMEM;
		goto fail;
	}
	r->u.generic_ip=ino;
#endif
	error=ntfs_alloc_file(NTFS_LINO2NINO(dir),ino,(char*)d->d_name.name,
			       d->d_name.len);
	if(error)goto fail;
	error=ntfs_update_inode(ino);
	if(error)goto fail;
	error=ntfs_update_inode(NTFS_LINO2NINO(dir));
	if(error)goto fail;

	r->i_uid=vol->uid;
	r->i_gid=vol->gid;
	/* FIXME: dirty? dev? */
	/* get the file modification times from the standard information */
	si=ntfs_find_attr(ino,vol->at_standard_information,NULL);
	if(si){
		char *attr=si->d.data;
		r->i_atime=ntfs_ntutc2unixutc(NTFS_GETU64(attr+0x18));
		r->i_ctime=ntfs_ntutc2unixutc(NTFS_GETU64(attr));
		r->i_mtime=ntfs_ntutc2unixutc(NTFS_GETU64(attr+8));
	}
	/* It's not a directory */
	r->i_op=&ntfs_inode_operations_nobmap;
	r->i_fop=&ntfs_file_operations_nommap,
	r->i_mode=S_IFREG|S_IRUGO;
#ifdef CONFIG_NTFS_RW
	r->i_mode|=S_IWUGO;
#endif
	r->i_mode &= ~vol->umask;

	insert_inode_hash(r);
	d_instantiate(d,r);
	return 0;
 fail:
	#ifndef NTFS_IN_LINUX_KERNEL
	if(ino)ntfs_free(ino);
	#endif
	if(r)iput(r);
	return -error;
}

static int
_linux_ntfs_mkdir(struct inode *dir, struct dentry* d, int mode)