inode.c

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/*
 *  linux/fs/sysv/inode.c
 *
 *  minix/inode.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  xenix/inode.c
 *  Copyright (C) 1992  Doug Evans
 *
 *  coh/inode.c
 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 *
 *  sysv/inode.c
 *  Copyright (C) 1993  Paul B. Monday
 *
 *  sysv/inode.c
 *  Copyright (C) 1993  Bruno Haible
 *
 *  This file contains code for allocating/freeing inodes and for read/writing
 *  the superblock.
 */

#include <linux/module.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sysv_fs.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/locks.h>

#include <asm/segment.h>

void sysv_put_inode(struct inode *inode)
{
	if (inode->i_nlink)
		return;
	inode->i_size = 0;
	sysv_truncate(inode);
	sysv_free_inode(inode);
}


static struct super_operations sysv_sops = { 
	sysv_read_inode,
	sysv_notify_change,
	sysv_write_inode,
	sysv_put_inode,
	sysv_put_super,
	sysv_write_super,
	sysv_statfs,
	NULL
};

/* The following functions try to recognize specific filesystems.
 * We recognize:
 * - Xenix FS by its magic number.
 * - SystemV FS by its magic number.
 * - Coherent FS by its funny fname/fpack field.
 * We discriminate among SystemV4 and SystemV2 FS by the assumption that
 * the time stamp is not < 01-01-1980.
 */

static void detected_bs512 (struct super_block *sb)
{
	sb->sv_block_size = 512;
	sb->sv_block_size_1 = 512-1;
	sb->sv_block_size_bits = 9;
	sb->sv_block_size_ratio = 2;
	sb->sv_block_size_ratio_bits = 1;
	sb->sv_inodes_per_block = 512/64;
	sb->sv_inodes_per_block_1 = 512/64-1;
	sb->sv_inodes_per_block_bits = 9-6;
	sb->sv_toobig_block = 10 + 
	  (sb->sv_ind_per_block = 512/4) +
	  (sb->sv_ind_per_block_2 = (512/4)*(512/4)) +
	  (sb->sv_ind_per_block_3 = (512/4)*(512/4)*(512/4));
	sb->sv_ind_per_block_1 = 512/4-1;
	sb->sv_ind_per_block_2_1 = (512/4)*(512/4)-1;
	sb->sv_ind_per_block_2_bits = 2 *
	  (sb->sv_ind_per_block_bits = 9-2);
	sb->sv_ind_per_block_block_size_1 = (512/4)*512-1;
	sb->sv_ind_per_block_block_size_bits = (9-2)+9;
	sb->sv_ind_per_block_2_block_size_1 = (512/4)*(512/4)*512-1;
	sb->sv_ind_per_block_2_block_size_bits = (9-2)+(9-2)+9;
	sb->sv_ind0_size = 10 * 512;
	sb->sv_ind1_size = (10 + (512/4))* 512;
	sb->sv_ind2_size = (10 + (512/4) + (512/4)*(512/4)) * 512;
}

static void detected_bs1024 (struct super_block *sb)
{
	sb->sv_block_size = 1024;
	sb->sv_block_size_1 = 1024-1;
	sb->sv_block_size_bits = 10;
	sb->sv_block_size_ratio = 1;
	sb->sv_block_size_ratio_bits = 0;
	sb->sv_inodes_per_block = 1024/64;
	sb->sv_inodes_per_block_1 = 1024/64-1;
	sb->sv_inodes_per_block_bits = 10-6;
	sb->sv_toobig_block = 10 + 
	  (sb->sv_ind_per_block = 1024/4) +
	  (sb->sv_ind_per_block_2 = (1024/4)*(1024/4)) +
	  (sb->sv_ind_per_block_3 = (1024/4)*(1024/4)*(1024/4));
	sb->sv_ind_per_block_1 = 1024/4-1;
	sb->sv_ind_per_block_2_1 = (1024/4)*(1024/4)-1;
	sb->sv_ind_per_block_2_bits = 2 *
	  (sb->sv_ind_per_block_bits = 10-2);
	sb->sv_ind_per_block_block_size_1 = (1024/4)*1024-1;
	sb->sv_ind_per_block_block_size_bits = (10-2)+10;
	sb->sv_ind_per_block_2_block_size_1 = (1024/4)*(1024/4)*1024-1;
	sb->sv_ind_per_block_2_block_size_bits = (10-2)+(10-2)+10;
	sb->sv_ind0_size = 10 * 1024;
	sb->sv_ind1_size = (10 + (1024/4))* 1024;
	sb->sv_ind2_size = (10 + (1024/4) + (1024/4)*(1024/4)) * 1024;
}

static const char* detect_xenix (struct super_block *sb, struct buffer_head *bh)
{
	struct xenix_super_block * sbd;

	sbd = (struct xenix_super_block *) bh->b_data;
	if (sbd->s_magic != 0x2b5544)
		return NULL;
	switch (sbd->s_type) {
		case 1: detected_bs512(sb); break;
		case 2: detected_bs1024(sb); break;
		default: return NULL;
	}
	sb->sv_type = FSTYPE_XENIX;
	return "Xenix";
}
static struct super_block * detected_xenix (struct super_block *sb, struct buffer_head *bh1, struct buffer_head *bh2)
{
	struct xenix_super_block * sbd1;
	struct xenix_super_block * sbd2;

	if (sb->sv_block_size == BLOCK_SIZE)
		/* block size = 1024, so bh1 = bh2 */
		sbd1 = sbd2 = (struct xenix_super_block *) bh1->b_data;
	else {
		/* block size = 512, so bh1 != bh2 */
		sbd1 = (struct xenix_super_block *) bh1->b_data;
		sbd2 = (struct xenix_super_block *) (bh2->b_data - BLOCK_SIZE/2);
		/* sanity check */
		if (sbd2->s_magic != 0x2b5544)
			return NULL;
	}

	sb->sv_convert = 0;
	sb->sv_kludge_symlinks = 1;
	sb->sv_truncate = 1;
	sb->sv_link_max = XENIX_LINK_MAX;
	sb->sv_fic_size = XENIX_NICINOD;
	sb->sv_flc_size = XENIX_NICFREE;
	sb->sv_bh1 = bh1;
	sb->sv_bh2 = bh2;
	sb->sv_sbd1 = (char *) sbd1;
	sb->sv_sbd2 = (char *) sbd2;
	sb->sv_sb_fic_count = &sbd1->s_ninode;
	sb->sv_sb_fic_inodes = &sbd1->s_inode[0];
	sb->sv_sb_total_free_inodes = &sbd2->s_tinode;
	sb->sv_sb_flc_count = &sbd1->s_nfree;
	sb->sv_sb_flc_blocks = &sbd1->s_free[0];
	sb->sv_sb_total_free_blocks = &sbd2->s_tfree;
	sb->sv_sb_time = &sbd2->s_time;
	sb->sv_block_base = 0;
	sb->sv_firstinodezone = 2;
	sb->sv_firstdatazone = sbd1->s_isize;
	sb->sv_nzones = sbd1->s_fsize;
	sb->sv_ndatazones = sb->sv_nzones - sb->sv_firstdatazone;
	return sb;
}

static const char* detect_sysv4 (struct super_block *sb, struct buffer_head *bh)
{
	struct sysv4_super_block * sbd;

	sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2);
	if (sbd->s_magic != 0xfd187e20)
		return NULL;
	if (sbd->s_time < 315532800) /* this is likely to happen on SystemV2 FS */
		return NULL;
	switch (sbd->s_type) {
		case 1: detected_bs512(sb); break;
		case 2: detected_bs1024(sb); break;
		default: return NULL;
	}
	sb->sv_type = FSTYPE_SYSV4;
	return "SystemV";
}
static struct super_block * detected_sysv4 (struct super_block *sb, struct buffer_head *bh)
{
	struct sysv4_super_block * sbd;

	if (sb->sv_block_size == BLOCK_SIZE)
		sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2);
	else {
		sbd = (struct sysv4_super_block *) bh->b_data;
		/* sanity check */
		if (sbd->s_magic != 0xfd187e20)
			return NULL;
		if (sbd->s_time < 315532800)
			return NULL;
	}

	sb->sv_convert = 0;
	sb->sv_kludge_symlinks = 0; /* ?? */
	sb->sv_truncate = 1;
	sb->sv_link_max = SYSV_LINK_MAX;
	sb->sv_fic_size = SYSV_NICINOD;
	sb->sv_flc_size = SYSV_NICFREE;
	sb->sv_bh1 = bh;
	sb->sv_bh2 = bh;
	sb->sv_sbd1 = (char *) sbd;
	sb->sv_sbd2 = (char *) sbd;
	sb->sv_sb_fic_count = &sbd->s_ninode;
	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
	sb->sv_sb_flc_count = &sbd->s_nfree;
	sb->sv_sb_flc_blocks = &sbd->s_free[0];
	sb->sv_sb_total_free_blocks = &sbd->s_tfree;
	sb->sv_sb_time = &sbd->s_time;
	sb->sv_sb_state = &sbd->s_state;
	sb->sv_block_base = 0;
	sb->sv_firstinodezone = 2;
	sb->sv_firstdatazone = sbd->s_isize;
	sb->sv_nzones = sbd->s_fsize;
	sb->sv_ndatazones = sb->sv_nzones - sb->sv_firstdatazone;
	return sb;
}

static const char* detect_sysv2 (struct super_block *sb, struct buffer_head *bh)
{
	struct sysv2_super_block * sbd;

	sbd = (struct sysv2_super_block *) (bh->b_data + BLOCK_SIZE/2);
	if (sbd->s_magic != 0xfd187e20)
		return NULL;
	if (sbd->s_time < 315532800) /* this is likely to happen on SystemV4 FS */
		return NULL;
	switch (sbd->s_type) {
		case 1: detected_bs512(sb); break;
		case 2: detected_bs1024(sb); break;
		default: return NULL;
	}
	sb->sv_type = FSTYPE_SYSV2;
	return "SystemV Release 2";
}
static struct super_block * detected_sysv2 (struct super_block *sb, struct buffer_head *bh)
{
	struct sysv2_super_block * sbd;

	if (sb->sv_block_size == BLOCK_SIZE)
		sbd = (struct sysv2_super_block *) (bh->b_data + BLOCK_SIZE/2);
	else {
		sbd = (struct sysv2_super_block *) bh->b_data;
		/* sanity check */
		if (sbd->s_magic != 0xfd187e20)
			return NULL;
		if (sbd->s_time < 315532800)
			return NULL;
	}

	sb->sv_convert = 0;
	sb->sv_kludge_symlinks = 0; /* ?? */
	sb->sv_truncate = 1;
	sb->sv_link_max = SYSV_LINK_MAX;
	sb->sv_fic_size = SYSV_NICINOD;
	sb->sv_flc_size = SYSV_NICFREE;
	sb->sv_bh1 = bh;
	sb->sv_bh2 = bh;
	sb->sv_sbd1 = (char *) sbd;
	sb->sv_sbd2 = (char *) sbd;
	sb->sv_sb_fic_count = &sbd->s_ninode;
	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
	sb->sv_sb_flc_count = &sbd->s_nfree;
	sb->sv_sb_flc_blocks = &sbd->s_free[0];
	sb->sv_sb_total_free_blocks = &sbd->s_tfree;
	sb->sv_sb_time = &sbd->s_time;
	sb->sv_sb_state = &sbd->s_state;
	sb->sv_block_base = 0;
	sb->sv_firstinodezone = 2;
	sb->sv_firstdatazone = sbd->s_isize;
	sb->sv_nzones = sbd->s_fsize;
	sb->sv_ndatazones = sb->sv_nzones - sb->sv_firstdatazone;
	return sb;
}

static const char* detect_coherent (struct super_block *sb, struct buffer_head *bh)
{
	struct coh_super_block * sbd;

	sbd = (struct coh_super_block *) (bh->b_data + BLOCK_SIZE/2);
	if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6))
	    || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6)))
		return NULL;
	detected_bs512(sb);
	sb->sv_type = FSTYPE_COH;
	return "Coherent";
}
static struct super_block * detected_coherent (struct super_block *sb, struct buffer_head *bh)
{
	struct coh_super_block * sbd;

	sbd = (struct coh_super_block *) bh->b_data;
	/* sanity check */
	if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6))
	    || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6)))
		return NULL;

	sb->sv_convert = 1;
	sb->sv_kludge_symlinks = 1;
	sb->sv_truncate = 1;
	sb->sv_link_max = COH_LINK_MAX;
	sb->sv_fic_size = COH_NICINOD;
	sb->sv_flc_size = COH_NICFREE;
	sb->sv_bh1 = bh;
	sb->sv_bh2 = bh;
	sb->sv_sbd1 = (char *) sbd;
	sb->sv_sbd2 = (char *) sbd;
	sb->sv_sb_fic_count = &sbd->s_ninode;
	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
	sb->sv_sb_flc_count = &sbd->s_nfree;
	sb->sv_sb_flc_blocks = &sbd->s_free[0];
	sb->sv_sb_total_free_blocks = &sbd->s_tfree;
	sb->sv_sb_time = &sbd->s_time;
	sb->sv_block_base = 0;
	sb->sv_firstinodezone = 2;
	sb->sv_firstdatazone = sbd->s_isize;
	sb->sv_nzones = from_coh_ulong(sbd->s_fsize);
	sb->sv_ndatazones = sb->sv_nzones - sb->sv_firstdatazone;
	return sb;
}

struct super_block *sysv_read_super(struct super_block *sb,void *data, 
				     int silent)
{
	struct buffer_head *bh;
	const char *found;
	kdev_t dev = sb->s_dev;

	if (1024 != sizeof (struct xenix_super_block))
		panic("Xenix FS: bad super-block size");
	if ((512 != sizeof (struct sysv4_super_block))
            || (512 != sizeof (struct sysv2_super_block)))
		panic("SystemV FS: bad super-block size");
	if (500 != sizeof (struct coh_super_block))
		panic("Coherent FS: bad super-block size");
	if (64 != sizeof (struct sysv_inode))
		panic("sysv fs: bad i-node size");
	MOD_INC_USE_COUNT;
	lock_super(sb);
	set_blocksize(dev,BLOCK_SIZE);

	/* Try to read Xenix superblock */
	if ((bh = bread(dev, 1, BLOCK_SIZE)) != NULL) {
		if ((found = detect_xenix(sb,bh)) != NULL)
			goto ok;
		brelse(bh);
	}
	if ((bh = bread(dev, 0, BLOCK_SIZE)) != NULL) {
		/* Try to recognize SystemV superblock */
		if ((found = detect_sysv4(sb,bh)) != NULL)
			goto ok;
		if ((found = detect_sysv2(sb,bh)) != NULL)
			goto ok;
		/* Try to recognize Coherent superblock */
		if ((found = detect_coherent(sb,bh)) != NULL)
			goto ok;
		brelse(bh);
	}
	/* Try to recognize SystemV superblock */
	/* Offset by 1 track, i.e. most probably 9, 15, or 18 kilobytes. */
	{	static int offsets[] = { 9, 15, 18, };
		int i;
		for (i = 0; i < sizeof(offsets)/sizeof(offsets[0]); i++)
			if ((bh = bread(dev, offsets[i], BLOCK_SIZE)) != NULL) {
				/* Try to recognize SystemV superblock */
				if ((found = detect_sysv4(sb,bh)) != NULL) {
					sb->sv_block_base = offsets[i] << sb->sv_block_size_ratio_bits;
					goto ok;
				}
				if ((found = detect_sysv2(sb,bh)) != NULL) {
					sb->sv_block_base = offsets[i] << sb->sv_block_size_ratio_bits;
					goto ok;
				}
				brelse(bh);
			}
	}
	sb->s_dev = 0;
	unlock_super(sb);
	if (!silent)
		printk("VFS: unable to read Xenix/SystemV/Coherent superblock on device "
		       "%s\n", kdevname(dev));
	failed:
	MOD_DEC_USE_COUNT;
	return NULL;

	ok:
	if (sb->sv_block_size == BLOCK_SIZE) {
		switch (sb->sv_type) {
			case FSTYPE_XENIX:
				if (!detected_xenix(sb,bh,bh))
					goto bad_superblock;
				break;
			case FSTYPE_SYSV4:
				if (!detected_sysv4(sb,bh))
					goto bad_superblock;
				break;
			case FSTYPE_SYSV2:
				if (!detected_sysv2(sb,bh))
					goto bad_superblock;
				break;
			default:
			bad_superblock:
				brelse(bh);
				sb->s_dev = 0;
				unlock_super(sb);
				printk("SysV FS: cannot read superblock in 1024 byte mode\n");
				goto failed;
		}
	} else {
		/* Switch to another block size. Unfortunately, we have to
		   release the 1 KB block bh and read it in two parts again. */
		struct buffer_head *bh1, *bh2;
		unsigned long blocknr = bh->b_blocknr << sb->sv_block_size_ratio_bits;

		brelse(bh);
		set_blocksize(dev,sb->sv_block_size);
		bh1 = NULL; bh2 = NULL;
		switch (sb->sv_type) {
			case FSTYPE_XENIX:
				if ((bh1 = bread(dev, blocknr, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_xenix(sb,bh1,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_SYSV4:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_sysv4(sb,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_SYSV2:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_sysv2(sb,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_COH:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_coherent(sb,bh2))
					goto bad_superblock2;
				break;
			default:
			bad_superblock2:
				brelse(bh1);
				brelse(bh2);
				set_blocksize(sb->s_dev,BLOCK_SIZE);
				sb->s_dev = 0;
				unlock_super(sb);
				printk("SysV FS: cannot read superblock in 512 byte mode\n");
				goto failed;
		}
	}
	sb->sv_ninodes = (sb->sv_firstdatazone - sb->sv_firstinodezone) << sb->sv_inodes_per_block_bits;
	if (!silent)
		printk("VFS: Found a %s FS (block size = %d) on device %s\n",
		       found, sb->sv_block_size, kdevname(dev));
	sb->s_magic = SYSV_MAGIC_BASE + sb->sv_type;
	/* The buffer code now supports block size 512 as well as 1024. */
	sb->s_blocksize = sb->sv_block_size;
	sb->s_blocksize_bits = sb->sv_block_size_bits;
	/* set up enough so that it can read an inode */
	sb->s_dev = dev;
	sb->s_op = &sysv_sops;
	sb->s_mounted = iget(sb,SYSV_ROOT_INO);
	unlock_super(sb);
	if (!sb->s_mounted) {
		printk("SysV FS: get root inode failed\n");
		sysv_put_super(sb);
		return NULL;
	}
	sb->s_dirt = 1;
	/* brelse(bh);  resp.  brelse(bh1); brelse(bh2);
	   occurs when the disk is unmounted. */
	return sb;
}

/* This is only called on sync() and umount(), when s_dirt=1. */
void sysv_write_super (struct super_block *sb)
{
	lock_super(sb);
	if (buffer_dirty(sb->sv_bh1) || buffer_dirty(sb->sv_bh2)) {
		/* If we are going to write out the super block,
		   then attach current time stamp.
		   But if the filesystem was marked clean, keep it clean. */
		unsigned long time = CURRENT_TIME;
		unsigned long old_time = *sb->sv_sb_time;
		if (sb->sv_convert)