inode.c

elinux jffs初始版本 具体了解JFFS的文件系统！

/*
 *  linux/fs/isofs/inode.c
 * 
 *  (C) 1991  Linus Torvalds - minix filesystem
 *      1992, 1993, 1994  Eric Youngdale Modified for ISO9660 filesystem.
 *      1994  Eberhard Moenkeberg - multi session handling.
 *      1995  Mark Dobie - allow mounting of some weird VideoCDs and PhotoCDs.
 *
 */

#include <linux/module.h>

#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/iso_fs.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/locks.h>
#include <linux/malloc.h>
#include <linux/errno.h>
#include <linux/cdrom.h>
#include <linux/nls.h>

#include <asm/system.h>
#include <asm/segment.h>

/*
 * We have no support for "multi volume" CDs, but more and more disks carry
 * wrong information within the volume descriptors.
 */
#define IGNORE_WRONG_MULTI_VOLUME_SPECS

#ifdef LEAK_CHECK
static int check_malloc = 0;
static int check_bread = 0;
#endif

void isofs_put_super(struct super_block *sb)
{
	if (sb->u.isofs_sb.s_nls_iocharset) {
		unload_nls(sb->u.isofs_sb.s_nls_iocharset);
		sb->u.isofs_sb.s_nls_iocharset = NULL;
	}
	lock_super(sb);

#ifdef LEAK_CHECK
	printk("Outstanding mallocs:%d, outstanding buffers: %d\n", 
	       check_malloc, check_bread);
#endif
	sb->s_dev = 0;
	unlock_super(sb);
	MOD_DEC_USE_COUNT;
	return;
}

static struct super_operations isofs_sops = { 
	isofs_read_inode,
	NULL,			/* notify_change */
	NULL,			/* write_inode */
	NULL,			/* put_inode */
	isofs_put_super,
	NULL,			/* write_super */
	isofs_statfs,
	NULL
};

struct iso9660_options{
  char map;
  char rock;
  char joliet;
  char cruft;
  char unhide;
  unsigned char check;
  unsigned char conversion;
  unsigned int blocksize;
  mode_t mode;
  gid_t gid;
  uid_t uid;
  char *iocharset;
  unsigned char utf8;
};

static int parse_options(char *options, struct iso9660_options * popt)
{
	char *this_char,*value,*p;
	int len;

	popt->map = 'n';
	popt->rock = 'y';
	popt->joliet = 'y';
	popt->cruft = 'n';
	popt->unhide = 'n';
	popt->check = 's';		/* default: strict */
	popt->conversion = 'b';		/* default: no conversion */
	popt->blocksize = 1024;
	popt->mode = S_IRUGO;
	popt->gid = 0;
	popt->uid = 0;
	popt->iocharset = NULL;
	popt->utf8 = 0;
	if (!options) return 1;
	for (this_char = strtok(options,","); this_char; this_char = strtok(NULL,",")) {
	        if (strncmp(this_char,"norock",6) == 0) {
		  popt->rock = 'n';
		  continue;
		}
	        if (strncmp(this_char,"nojoliet",8) == 0) {
		  popt->joliet = 'n';
		  continue;
		}
	        if (strncmp(this_char,"unhide",6) == 0) {
		  popt->unhide = 'y';
		  continue;
		}
	        if (strncmp(this_char,"cruft",5) == 0) {
		  popt->cruft = 'y';
		  continue;
		}
	        if (strncmp(this_char,"utf8",4) == 0) {
		  popt->utf8 = 1;
		  continue;
		}
		if ((value = strchr(this_char,'=')) != NULL)
			*value++ = 0;

		if (!strcmp(this_char,"iocharset")) {
			p = value;
			while (*value && *value != ',') value++;
			len = value - p;
			if (len) {
				popt->iocharset = kmalloc(len+1, GFP_KERNEL);
				memcpy(popt->iocharset, p, len);
				popt->iocharset[len] = 0;
			} else {
				popt->iocharset = NULL;
				return 0;
			}
		}
		else if (!strcmp(this_char,"map") && value) {
			if (value[0] && !value[1] && strchr("on",*value))
				popt->map = *value;
			else if (!strcmp(value,"off")) popt->map = 'o';
			else if (!strcmp(value,"normal")) popt->map = 'n';
			else return 0;
		}
		else if (!strcmp(this_char,"check") && value) {
			if (value[0] && !value[1] && strchr("rs",*value))
				popt->check = *value;
			else if (!strcmp(value,"relaxed")) popt->check = 'r';
			else if (!strcmp(value,"strict")) popt->check = 's';
			else return 0;
		}
		else if (!strcmp(this_char,"conv") && value) {
			if (value[0] && !value[1] && strchr("btma",*value))
				popt->conversion = *value;
			else if (!strcmp(value,"binary")) popt->conversion = 'b';
			else if (!strcmp(value,"text")) popt->conversion = 't';
			else if (!strcmp(value,"mtext")) popt->conversion = 'm';
			else if (!strcmp(value,"auto")) popt->conversion = 'a';
			else return 0;
		}
		else if (value && 
			 (!strcmp(this_char,"block") ||
			  !strcmp(this_char,"mode") ||
			  !strcmp(this_char,"uid") ||
			  !strcmp(this_char,"gid"))) {
		  char * vpnt = value;
		  unsigned int ivalue = simple_strtoul(vpnt, &vpnt, 0);
		  if (*vpnt) return 0;
		  switch(*this_char) {
		  case 'b':
		    if (   ivalue != 512 
			&& ivalue != 1024 
			&& ivalue != 2048) return 0;
		    popt->blocksize = ivalue;
		    break;
		  case 'u':
		    popt->uid = ivalue;
		    break;
		  case 'g':
		    popt->gid = ivalue;
		    break;
		  case 'm':
		    popt->mode = ivalue;
		    break;
		  }
		}
		else return 1;
	}
	return 1;
}

/*
 * look if the driver can tell the multi session redirection value
 *
 * don't change this if you don't know what you do, please!
 * Multisession is legal only with XA disks.
 * A non-XA disk with more than one volume descriptor may do it right, but
 * usually is written in a nowhere standardized "multi-partition" manner.
 * Multisession uses absolute addressing (solely the first frame of the whole
 * track is #0), multi-partition uses relative addressing (each first frame of
 * each track is #0), and a track is not a session.
 *
 * A broken CDwriter software or drive firmware does not set new standards,
 * at least not if conflicting with the existing ones.
 * 
 * [e-mail]
 */
#define WE_OBEY_THE_WRITTEN_STANDARDS 1

static unsigned int isofs_get_last_session(kdev_t dev)
{
  struct cdrom_multisession ms_info;
  unsigned int vol_desc_start;
  struct inode inode_fake;
  extern struct file_operations * get_blkfops(unsigned int);
  int i;

  vol_desc_start=0;
  if (get_blkfops(MAJOR(dev))->ioctl!=NULL)
    {
      /* Whoops.  We must save the old FS, since otherwise
       * we would destroy the kernels idea about FS on root
       * mount in read_super... [chexum]
       */
      unsigned long old_fs=get_fs();
      inode_fake.i_rdev=dev;
      ms_info.addr_format=CDROM_LBA;
      set_fs(KERNEL_DS);
      i=get_blkfops(MAJOR(dev))->ioctl(&inode_fake,
				       NULL,
				       CDROMMULTISESSION,
				       (unsigned long) &ms_info);
      set_fs(old_fs);
#if 0 
      printk("isofs.inode: CDROMMULTISESSION: rc=%d\n",i);
      if (i==0)
	{
	  printk("isofs.inode: XA disk: %s\n", ms_info.xa_flag ? "yes":"no");
	  printk("isofs.inode: vol_desc_start = %d\n", ms_info.addr.lba);
	}
#endif 0
      if (i==0)
#if WE_OBEY_THE_WRITTEN_STANDARDS
        if (ms_info.xa_flag) /* necessary for a valid ms_info.addr */
#endif WE_OBEY_THE_WRITTEN_STANDARDS
          vol_desc_start=ms_info.addr.lba;
    }
  return vol_desc_start;
}

struct super_block *isofs_read_super(struct super_block *s,void *data,
				     int silent)
{
	struct buffer_head *bh=NULL;
	int iso_blknum;
	unsigned int blocksize_bits;
	int high_sierra;
	kdev_t dev = s->s_dev;
	unsigned int vol_desc_start;
	int orig_zonesize;
	char *p;
	int joliet_level = 0;

	struct iso_volume_descriptor *vdp;
	struct hs_volume_descriptor *hdp;

	struct iso_primary_descriptor *pri = NULL;
	struct iso_supplementary_descriptor *sec = NULL;
	struct hs_primary_descriptor *h_pri = NULL;

	struct iso_directory_record *rootp;

	struct iso9660_options opt;

	MOD_INC_USE_COUNT;

	if (!parse_options((char *) data,&opt)) {
		s->s_dev = 0;
		MOD_DEC_USE_COUNT;
		return NULL;
	}

#if 0
	printk("map = %c\n", opt.map);
	printk("rock = %c\n", opt.rock);
	printk("joliet = %c\n", opt.joliet);
	printk("check = %c\n", opt.check);
	printk("cruft = %c\n", opt.cruft);
	printk("unhide = %c\n", opt.unhide);
	printk("conversion = %c\n", opt.conversion);
	printk("blocksize = %d\n", opt.blocksize);
	printk("gid = %d\n", opt.gid);
	printk("uid = %d\n", opt.uid);
#endif
	
	blocksize_bits = 0;
	{
	  int i = opt.blocksize;
	  while (i != 1){
	    blocksize_bits++;
	    i >>=1;
	  }
	}
	set_blocksize(dev, opt.blocksize);

	lock_super(s);

	s->u.isofs_sb.s_high_sierra = high_sierra = 0; /* default is iso9660 */

	vol_desc_start = isofs_get_last_session(dev);
	
	for (iso_blknum = vol_desc_start+16;
             iso_blknum < vol_desc_start+100; iso_blknum++)
	{
	    int b = iso_blknum << (ISOFS_BLOCK_BITS-blocksize_bits);

	    if (!(bh = bread(dev,b,opt.blocksize))) {
		s->s_dev = 0;
		printk("isofs_read_super: bread failed, dev "
		       "%s iso_blknum %d block %d\n",
		       kdevname(dev), iso_blknum, b);
		unlock_super(s);
		MOD_DEC_USE_COUNT;
		return NULL;
	    }

	    vdp = (struct iso_volume_descriptor *)bh->b_data;
	    hdp = (struct hs_volume_descriptor *)bh->b_data;
	    
	    if (strncmp (hdp->id, HS_STANDARD_ID, sizeof hdp->id) == 0) {
		if (isonum_711 (hdp->type) != ISO_VD_PRIMARY)
		    goto out;
		if (isonum_711 (hdp->type) == ISO_VD_END)
		    goto out;
		
		s->u.isofs_sb.s_high_sierra = 1;
		high_sierra = 1;
		opt.rock = 'n';
		h_pri = (struct hs_primary_descriptor *)vdp;
		break;
	    }

	    if (strncmp (vdp->id, ISO_STANDARD_ID, sizeof vdp->id) == 0) {
		if (isonum_711 (vdp->type) == ISO_VD_END)
		    break;
		if (isonum_711 (vdp->type) == ISO_VD_PRIMARY) {
		    if (pri == NULL) {
			pri = (struct iso_primary_descriptor *)vdp;
		    }
		} else if (isonum_711 (vdp->type) == ISO_VD_SUPPLEMENTARY) {
		    sec = (struct iso_supplementary_descriptor *)vdp;
		    if (sec->escape[0] == 0x25 && sec->escape[1] == 0x2f) {
			if (opt.joliet == 'y') {
			    if (sec->escape[2] == 0x40) {
				joliet_level = 1;
			    } else if (sec->escape[2] == 0x43) {
				joliet_level = 2;
			    } else if (sec->escape[2] == 0x45) {
				joliet_level = 3;
			    }
			    printk("ISO9660 Extensions: Microsoft Joliet Level %d\n",
				   joliet_level);
			}
			break;
		    } else {
			/* Unknown supplementary volume descriptor */
			sec = NULL;
		    }
		}
		/* Just skip any volume descriptors we don't recognize */
	    }

	    brelse(bh);
	}
	if ((pri == NULL) && (sec == NULL) && (h_pri == NULL)) {
	    if (!silent)
		printk("Unable to identify CD-ROM format.\n");
	    s->s_dev = 0;
	    unlock_super(s);
	    MOD_DEC_USE_COUNT;
	    return NULL;
	}
	s->u.isofs_sb.s_joliet_level = joliet_level;
	if (joliet_level && opt.rock == 'n') {
	    /* This is the case of Joliet with the norock mount flag.
	     * A disc with both Joliet and Rock Ridge is handled later
	     */
	    pri = (struct iso_primary_descriptor *) sec;
	}

	if(high_sierra){