C++ BEFS_SB函数代码示例

/**
 * befs_read_datastream - get buffer_head containing data, starting from pos.
 * @sb: Filesystem superblock
 * @ds: datastrem to find data with
 * @pos: start of data
 * @off: offset of data in buffer_head->b_data
 *
 * Returns pointer to buffer_head containing data starting with offset @off,
 * if you don't need to know offset just set @off = NULL.
 */
struct buffer_head *
befs_read_datastream(struct super_block *sb, befs_data_stream * ds,
		     befs_off_t pos, uint * off)
{
	struct buffer_head *bh = NULL;
	befs_block_run run;
	befs_blocknr_t block;	/* block coresponding to pos */

	befs_debug(sb, "---> befs_read_datastream() %Lu", pos);
	block = pos >> BEFS_SB(sb)->block_shift;
	if (off)
		*off = pos - (block << BEFS_SB(sb)->block_shift);

	if (befs_fblock2brun(sb, ds, block, &run) != BEFS_OK) {
		befs_error(sb, "BeFS: Error finding disk addr of block %lu",
			   block);
		befs_debug(sb, "<--- befs_read_datastream() ERROR");
		return NULL;
	}
	bh = befs_bread_iaddr(sb, run);
	if (!bh) {
		befs_error(sb, "BeFS: Error reading block %lu from datastream",
			   block);
		return NULL;
	}

	befs_debug(sb, "<--- befs_read_datastream() read data, starting at %Lu",
		   pos);

	return bh;
}

/**
 * befs_read_lsmylink - read long symlink from datastream.
 * @sb: Filesystem superblock 
 * @ds: Datastrem to read from
 * @buf: Buffer in which to place long symlink data
 * @len: Length of the long symlink in bytes
 *
 * Returns the number of bytes read
 */
size_t
befs_read_lsymlink(struct super_block * sb, befs_data_stream * ds, void *buff,
		   befs_off_t len)
{
	befs_off_t bytes_read = 0;	/* bytes readed */
	u16 plen;
	struct buffer_head *bh = NULL;
	befs_debug(sb, "---> befs_read_lsymlink() length: %Lu", len);

	while (bytes_read < len) {
		bh = befs_read_datastream(sb, ds, bytes_read, NULL);
		if (!bh) {
			befs_error(sb, "BeFS: Error reading datastream block "
				   "starting from %Lu", bytes_read);
			befs_debug(sb, "<--- befs_read_lsymlink() ERROR");
			return bytes_read;

		}
		plen = ((bytes_read + BEFS_SB(sb)->block_size) < len) ?
		    BEFS_SB(sb)->block_size : len - bytes_read;
		memcpy(buff + bytes_read, bh->b_data, plen);
		brelse(bh);
		bytes_read += plen;
	}

	befs_debug(sb, "<--- befs_read_lsymlink() read %u bytes", bytes_read);
	return bytes_read;
}

/* This function has the responsibiltiy of getting the
 * filesystem ready for unmounting. 
 * Basically, we free everything that we allocated in
 * befs_read_inode
 */
static void
befs_put_super(struct super_block *sb)
{
	kfree(BEFS_SB(sb)->mount_opts.iocharset);
	BEFS_SB(sb)->mount_opts.iocharset = NULL;
	unload_nls(BEFS_SB(sb)->nls);
	kfree(sb->s_fs_info);
	sb->s_fs_info = NULL;
}

struct buffer_head *
befs_bread_iaddr(struct super_block *sb, befs_inode_addr iaddr)
{
    struct buffer_head *bh = NULL;
    befs_blocknr_t block = 0;
    befs_sb_info *befs_sb = BEFS_SB(sb);

    befs_debug(sb, "---> Enter befs_read_iaddr() "
           "[%u, %hu, %hu]",
           iaddr.allocation_group, iaddr.start, iaddr.len);

    if (iaddr.allocation_group > befs_sb->num_ags) {
        befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
               iaddr.allocation_group, befs_sb->num_ags);
        goto error;
    }

    block = iaddr2blockno(sb, &iaddr);

    befs_debug(sb, "befs_read_iaddr: offset = %lu", block);

    bh = sb_bread(sb, block);

    if (bh == NULL) {
        befs_error(sb, "Failed to read block %lu", block);
        goto error;
    }

    befs_debug(sb, "<--- befs_read_iaddr()");
    return bh;

      error:
    befs_debug(sb, "<--- befs_read_iaddr() ERROR");
    return NULL;
}

/**
 * load_befs_sb -- Read from disk and properly byteswap all the fields
 * of the befs superblock
 *
 *
 *
 *
 */
int
befs_load_sb(struct super_block *sb, befs_super_block * disk_sb)
{
	befs_sb_info *befs_sb = BEFS_SB(sb);

	/* Check the byte order of the filesystem */
	if (le32_to_cpu(disk_sb->fs_byte_order) == BEFS_BYTEORDER_NATIVE)
		befs_sb->byte_order = BEFS_BYTESEX_LE;
	else if (be32_to_cpu(disk_sb->fs_byte_order) == BEFS_BYTEORDER_NATIVE)
		befs_sb->byte_order = BEFS_BYTESEX_BE;

	befs_sb->magic1 = fs32_to_cpu(sb, disk_sb->magic1);
	befs_sb->magic2 = fs32_to_cpu(sb, disk_sb->magic2);
	befs_sb->magic3 = fs32_to_cpu(sb, disk_sb->magic3);
	befs_sb->block_size = fs32_to_cpu(sb, disk_sb->block_size);
	befs_sb->block_shift = fs32_to_cpu(sb, disk_sb->block_shift);
	befs_sb->num_blocks = fs64_to_cpu(sb, disk_sb->num_blocks);
	befs_sb->used_blocks = fs64_to_cpu(sb, disk_sb->used_blocks);
	befs_sb->inode_size = fs32_to_cpu(sb, disk_sb->inode_size);

	befs_sb->blocks_per_ag = fs32_to_cpu(sb, disk_sb->blocks_per_ag);
	befs_sb->ag_shift = fs32_to_cpu(sb, disk_sb->ag_shift);
	befs_sb->num_ags = fs32_to_cpu(sb, disk_sb->num_ags);

	befs_sb->log_blocks = fsrun_to_cpu(sb, disk_sb->log_blocks);
	befs_sb->log_start = fs64_to_cpu(sb, disk_sb->log_start);
	befs_sb->log_end = fs64_to_cpu(sb, disk_sb->log_end);

	befs_sb->root_dir = fsrun_to_cpu(sb, disk_sb->root_dir);
	befs_sb->indices = fsrun_to_cpu(sb, disk_sb->indices);
	befs_sb->nls = NULL;

	return BEFS_OK;
}

/*
	Finds the block run that starts at file block number blockno
	in the file represented by the datastream data, if that 
	blockno is in the direct region of the datastream.
	
	sb: the superblock
	data: the datastream
	blockno: the blocknumber to find
	run: The found run is passed back through this pointer
	
	Return value is BEFS_OK if the blockrun is found, BEFS_ERR
	otherwise.
	
	Algorithm:
	Linear search. Checks each element of array[] to see if it
	contains the blockno-th filesystem block. This is necessary
	because the block runs map variable amounts of data. Simply
	keeps a count of the number of blocks searched so far (sum),
	incrementing this by the length of each block run as we come
	across it. Adds sum to *count before returning (this is so
	you can search multiple arrays that are logicaly one array,
	as in the indirect region code).
	
	When/if blockno is found, if blockno is inside of a block 
	run as stored on disk, we offset the start and lenght members 
	of the block run, so that blockno is the start and len is
	still valid (the run ends in the same place).
	
	2001-11-15 Will Dyson
*/
static int
befs_find_brun_direct(struct super_block *sb, befs_data_stream * data,
		      befs_blocknr_t blockno, befs_block_run * run)
{
	int i;
	befs_block_run *array = data->direct;
	befs_blocknr_t sum;
	befs_blocknr_t max_block =
	    data->max_direct_range >> BEFS_SB(sb)->block_shift;

	befs_debug(sb, "---> befs_find_brun_direct(), find %lu", blockno);

	if (blockno > max_block) {
		befs_error(sb, "befs_find_brun_direct() passed block outside of"
			   "direct region");
		return BEFS_ERR;
	}

	for (i = 0, sum = 0; i < BEFS_NUM_DIRECT_BLOCKS;
	     sum += array[i].len, i++) {
		if (blockno >= sum && blockno < sum + (array[i].len)) {
			int offset = blockno - sum;
			run->allocation_group = array[i].allocation_group;
			run->start = array[i].start + offset;
			run->len = array[i].len - offset;

			befs_debug(sb, "---> befs_find_brun_direct(), "
				   "found %lu at direct[%d]", blockno, i);
			return BEFS_OK;
		}
	}

	befs_debug(sb, "---> befs_find_brun_direct() ERROR");
	return BEFS_ERR;
}

static int
befs_readdir(struct file *file, struct dir_context *ctx)
{
	struct inode *inode = file_inode(file);
	struct super_block *sb = inode->i_sb;
	befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
	befs_off_t value;
	int result;
	size_t keysize;
	unsigned char d_type;
	char keybuf[BEFS_NAME_LEN + 1];

	befs_debug(sb, "---> %s name %pD, inode %ld, ctx->pos %lld",
		  __func__, file, inode->i_ino, ctx->pos);

more:
	result = befs_btree_read(sb, ds, ctx->pos, BEFS_NAME_LEN + 1,
				 keybuf, &keysize, &value);

	if (result == BEFS_ERR) {
		befs_debug(sb, "<--- %s ERROR", __func__);
		befs_error(sb, "IO error reading %pD (inode %lu)",
			   file, inode->i_ino);
		return -EIO;

	} else if (result == BEFS_BT_END) {
		befs_debug(sb, "<--- %s END", __func__);
		return 0;

	} else if (result == BEFS_BT_EMPTY) {
		befs_debug(sb, "<--- %s Empty directory", __func__);
		return 0;
	}

	d_type = DT_UNKNOWN;

	/* Convert to NLS */
	if (BEFS_SB(sb)->nls) {
		char *nlsname;
		int nlsnamelen;
		result =
		    befs_utf2nls(sb, keybuf, keysize, &nlsname, &nlsnamelen);
		if (result < 0) {
			befs_debug(sb, "<--- %s ERROR", __func__);
			return result;
		}
		if (!dir_emit(ctx, nlsname, nlsnamelen,
				 (ino_t) value, d_type)) {
			kfree(nlsname);
			return 0;
		}
		kfree(nlsname);
	} else {
		if (!dir_emit(ctx, keybuf, keysize,
				 (ino_t) value, d_type))
			return 0;
	}
	ctx->pos++;
	goto more;
}

void
befs_debug(const struct super_block *sb, const char *fmt, ...)
{
#ifdef CONFIG_BEFS_DEBUG

	va_list args;
	char *err_buf = NULL;

	if (BEFS_SB(sb)->mount_opts.debug) {
		err_buf = (char *) kmalloc(ERRBUFSIZE, GFP_KERNEL);
		if (err_buf == NULL) {
			printk(KERN_ERR "could not allocate %d bytes\n",
				ERRBUFSIZE);
			return;
		}

		va_start(args, fmt);
		vsnprintf(err_buf, ERRBUFSIZE, fmt, args);
		va_end(args);

		printk(KERN_DEBUG "BeFS(%s): %s\n", sb->s_id, err_buf);

		kfree(err_buf);
	}

#endif				//CONFIG_BEFS_DEBUG
}

static int
befs_utf2nls(struct super_block *sb, const char *in,
	     int in_len, char **out, int *out_len)
{
	struct nls_table *nls = BEFS_SB(sb)->nls;
	int i, o;
	unicode_t uni;
	int unilen, utflen;
	char *result;
	/* The utf8->nls conversion won't make the final nls string bigger
	 * than the utf one, but if the string is pure ascii they'll have the
	 * same width and an extra char is needed to save the additional \0
	 */
	int maxlen = in_len + 1;

	befs_debug(sb, "---> utf2nls()");

	if (!nls) {
		befs_error(sb, "befs_utf2nls called with no NLS table loaded");
		return -EINVAL;
	}

	*out = result = kmalloc(maxlen, GFP_NOFS);
	if (!*out) {
		befs_error(sb, "befs_utf2nls() cannot allocate memory");
		*out_len = 0;
		return -ENOMEM;
	}

	for (i = o = 0; i < in_len; i += utflen, o += unilen) {

		/* convert from UTF-8 to Unicode */
		utflen = utf8_to_utf32(&in[i], in_len - i, &uni);
		if (utflen < 0)
			goto conv_err;

		/* convert from Unicode to nls */
		if (uni > MAX_WCHAR_T)
			goto conv_err;
		unilen = nls->uni2char(uni, &result[o], in_len - o);
		if (unilen < 0)
			goto conv_err;
	}
	result[o] = '\0';
	*out_len = o;

	befs_debug(sb, "<--- utf2nls()");

	return o;

      conv_err:
	befs_error(sb, "Name using character set %s contains a character that "
		   "cannot be converted to unicode.", nls->charset);
	befs_debug(sb, "<--- utf2nls()");
	kfree(result);
	return -EILSEQ;
}

static int
befs_nls2utf(struct super_block *sb, const char *in,
	     int in_len, char **out, int *out_len)
{
	struct nls_table *nls = BEFS_SB(sb)->nls;
	int i, o;
	wchar_t uni;
	int unilen, utflen;
	char *result;
	/* There're nls characters that will translate to 3-chars-wide UTF-8
	 * characters, a additional byte is needed to save the final \0
	 * in special cases */
	int maxlen = (3 * in_len) + 1;

	befs_debug(sb, "---> nls2utf()\n");

	if (!nls) {
		befs_error(sb, "befs_nls2utf called with no NLS table loaded.");
		return -EINVAL;
	}

	*out = result = kmalloc(maxlen, GFP_NOFS);
	if (!*out) {
		befs_error(sb, "befs_nls2utf() cannot allocate memory");
		*out_len = 0;
		return -ENOMEM;
	}

	for (i = o = 0; i < in_len; i += unilen, o += utflen) {

		/* convert from nls to unicode */
		unilen = nls->char2uni(&in[i], in_len - i, &uni);
		if (unilen < 0) {
			goto conv_err;
		}

		/* convert from unicode to UTF-8 */
		utflen = utf8_wctomb(&result[o], uni, 3);
		if (utflen <= 0) {
			goto conv_err;
		}
	}

	result[o] = '\0';
	*out_len = o;

	befs_debug(sb, "<--- nls2utf()");

	return i;

      conv_err:
	befs_error(sb, "Name using charecter set %s contains a charecter that "
		   "cannot be converted to unicode.", nls->charset);
	befs_debug(sb, "<--- nls2utf()");
	kfree(result);
	return -EILSEQ;
}

static int
befs_statfs(struct super_block *sb, struct kstatfs *buf)
{

	befs_debug(sb, "---> befs_statfs()");

	buf->f_type = BEFS_SUPER_MAGIC;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = BEFS_SB(sb)->num_blocks;
	buf->f_bfree = BEFS_SB(sb)->num_blocks - BEFS_SB(sb)->used_blocks;
	buf->f_bavail = buf->f_bfree;
	buf->f_files = 0;	/* UNKNOWN */
	buf->f_ffree = 0;	/* UNKNOWN */
	buf->f_namelen = BEFS_NAME_LEN;

	befs_debug(sb, "<--- befs_statfs()");

	return 0;
}

int
befs_check_sb(struct super_block *sb)
{
	befs_sb_info *befs_sb = BEFS_SB(sb);

	/* Check magic headers of super block */
	if ((befs_sb->magic1 != BEFS_SUPER_MAGIC1)
	    || (befs_sb->magic2 != BEFS_SUPER_MAGIC2)
	    || (befs_sb->magic3 != BEFS_SUPER_MAGIC3)) {
		befs_error(sb, "invalid magic header");
		return BEFS_ERR;
	}

	/*
	 * Check blocksize of BEFS.
	 *
	 * Blocksize of BEFS is 1024, 2048, 4096 or 8192.
	 */

	if ((befs_sb->block_size != 1024)
	    && (befs_sb->block_size != 2048)
	    && (befs_sb->block_size != 4096)
	    && (befs_sb->block_size != 8192)) {
		befs_error(sb, "invalid blocksize: %u", befs_sb->block_size);
		return BEFS_ERR;
	}

	if (befs_sb->block_size > PAGE_SIZE) {
		befs_error(sb, "blocksize(%u) cannot be larger"
			   "than system pagesize(%lu)", befs_sb->block_size,
			   PAGE_SIZE);
		return BEFS_ERR;
	}

	/*
	   * block_shift and block_size encode the same information
	   * in different ways as a consistency check.
	 */

	if ((1 << befs_sb->block_shift) != befs_sb->block_size) {
		befs_error(sb, "block_shift disagrees with block_size. "
			   "Corruption likely.");
		return BEFS_ERR;
	}

	if (befs_sb->log_start != befs_sb->log_end) {
		befs_error(sb, "Filesystem not clean! There are blocks in the "
			   "journal. You must boot into BeOS and mount this volume "
			   "to make it clean.");
		return BEFS_ERR;
	}

	return BEFS_OK;
}

static int
befs_utf2nls(struct super_block *sb, const char *in,
	     int in_len, char **out, int *out_len)
{
	struct nls_table *nls = BEFS_SB(sb)->nls;
	int i, o;
	wchar_t uni;
	int unilen, utflen;
	char *result;
	int maxlen = in_len; /* The utf8->nls conversion can't make more chars */

	befs_debug(sb, "---> utf2nls()");

	if (!nls) {
		befs_error(sb, "befs_utf2nls called with no NLS table loaded");
		return -EINVAL;
	}

	*out = result = kmalloc(maxlen, GFP_NOFS);
	if (!*out) {
		befs_error(sb, "befs_utf2nls() cannot allocate memory");
		*out_len = 0;
		return -ENOMEM;
	}

	for (i = o = 0; i < in_len; i += utflen, o += unilen) {

		/* convert from UTF-8 to Unicode */
		utflen = utf8_mbtowc(&uni, &in[i], in_len - i);
		if (utflen < 0) {
			goto conv_err;
		}

		/* convert from Unicode to nls */
		unilen = nls->uni2char(uni, &result[o], in_len - o);
		if (unilen < 0) {
			goto conv_err;
		}
	}
	result[o] = '\0';
	*out_len = o;

	befs_debug(sb, "<--- utf2nls()");

	return o;

      conv_err:
	befs_error(sb, "Name using character set %s contains a character that "
		   "cannot be converted to unicode.", nls->charset);
	befs_debug(sb, "<--- utf2nls()");
	kfree(result);
	return -EILSEQ;
}

static int
befs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
	struct super_block *sb = dentry->d_sb;
	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

	befs_debug(sb, "---> befs_statfs()");

	buf->f_type = BEFS_SUPER_MAGIC;
	buf->f_bsize = sb->s_blocksize;
	buf->f_blocks = BEFS_SB(sb)->num_blocks;
	buf->f_bfree = BEFS_SB(sb)->num_blocks - BEFS_SB(sb)->used_blocks;
	buf->f_bavail = buf->f_bfree;
	buf->f_files = 0;	/* UNKNOWN */
	buf->f_ffree = 0;	/* UNKNOWN */
	buf->f_fsid.val[0] = (u32)id;
	buf->f_fsid.val[1] = (u32)(id >> 32);
	buf->f_namelen = BEFS_NAME_LEN;

	befs_debug(sb, "<--- befs_statfs()");

	return 0;
}

static struct dentry *
befs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
	struct inode *inode = NULL;
	struct super_block *sb = dir->i_sb;
	befs_data_stream *ds = &BEFS_I(dir)->i_data.ds;
	befs_off_t offset;
	int ret;
	int utfnamelen;
	char *utfname;
	const char *name = dentry->d_name.name;

	befs_debug(sb, "---> befs_lookup() "
		   "name %s inode %ld", dentry->d_name.name, dir->i_ino);

	/* Convert to UTF-8 */
	if (BEFS_SB(sb)->nls) {
		ret =
		    befs_nls2utf(sb, name, strlen(name), &utfname, &utfnamelen);
		if (ret < 0) {
			befs_debug(sb, "<--- befs_lookup() ERROR");
			return ERR_PTR(ret);
		}
		ret = befs_btree_find(sb, ds, utfname, &offset);
		kfree(utfname);

	} else {
		ret = befs_btree_find(sb, ds, dentry->d_name.name, &offset);
	}

	if (ret == BEFS_BT_NOT_FOUND) {
		befs_debug(sb, "<--- befs_lookup() %s not found",
			   dentry->d_name.name);
		return ERR_PTR(-ENOENT);

	} else if (ret != BEFS_OK || offset == 0) {
		befs_warning(sb, "<--- befs_lookup() Error");
		return ERR_PTR(-ENODATA);
	}

	inode = befs_iget(dir->i_sb, (ino_t) offset);
	if (IS_ERR(inode))
		return ERR_CAST(inode);

	d_add(dentry, inode);

	befs_debug(sb, "<--- befs_lookup()");

	return NULL;
}