Re: [RFC][patch] VMUFAT filesystem - v3

[Adrian McMenamin <adrian@newgolddream.dyndns.info>]

A further quick clean up.

 fs/Kconfig         |    1 +
 fs/Makefile        |    1 +
 fs/vmufat/Kconfig  |   14 +
 fs/vmufat/Makefile |    7 +
 fs/vmufat/inode.c  | 1394 ++++++++++++++++++++++++++++++++++++++++++++++++++++

Signed-off by: Adrian McMenamin
---
diff --git a/fs/Kconfig b/fs/Kconfig
index 9f7270f..b7cb23d 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -176,6 +176,7 @@ source "fs/romfs/Kconfig"
 source "fs/sysv/Kconfig"
 source "fs/ufs/Kconfig"
 source "fs/exofs/Kconfig"
+source "fs/vmufat/Kconfig"
 
 config NILFS2_FS
 	tristate "NILFS2 file system support (EXPERIMENTAL)"
diff --git a/fs/Makefile b/fs/Makefile
index af6d047..9d2d469 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -124,3 +124,4 @@ obj-$(CONFIG_OCFS2_FS)		+= ocfs2/
 obj-$(CONFIG_BTRFS_FS)		+= btrfs/
 obj-$(CONFIG_GFS2_FS)           += gfs2/
 obj-$(CONFIG_EXOFS_FS)          += exofs/
+obj-$(CONFIG_VMUFAT_FS)		+= vmufat/
diff --git a/fs/vmufat/Kconfig b/fs/vmufat/Kconfig
new file mode 100644
index 0000000..bdad4c6
--- /dev/null
+++ b/fs/vmufat/Kconfig
@@ -0,0 +1,14 @@
+config VMUFAT_FS
+	tristate "Dreamcast VMU FAT filesystem"
+	depends on BLOCK
+	help
+	  This implements the simple FAT type filesystem found on SEGA
+	  Dreamcast visual memory units.
+
+	  Dreamcast users who want to mount their VMUs to view the native
+	  filesystem will say 'Y' here. The filesystem is hardware independent
+	  but is not recommended for any serious use in other circumstances, so
+	  just about everyone else should say 'N'.
+
+	  To compile this as a module say 'M' here. The module will be called
+	  vmufat
diff --git a/fs/vmufat/Makefile b/fs/vmufat/Makefile
new file mode 100644
index 0000000..c716ead
--- /dev/null
+++ b/fs/vmufat/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for VMUFAT filesystem
+#
+
+obj-$(CONFIG_VMUFAT_FS) += vmufat.o
+
+vmufat-objs := inode.o
diff --git a/fs/vmufat/inode.c b/fs/vmufat/inode.c
new file mode 100644
index 0000000..a65ac84
--- /dev/null
+++ b/fs/vmufat/inode.c
@@ -0,0 +1,1394 @@
+/*
+ * inode operations for the VMU file system
+ *
+ * Copyright (C) 2002 - 2009	Adrian McMenamin
+ * Copyright (C) 2002		Paul Mundt
+ *
+ * Released under the terms of the GNU GPL.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/statfs.h>
+#include <linux/mpage.h>
+#include <linux/bcd.h>
+
+#define VMUFAT_NAMELEN 12
+
+/* GNU utils won't list files with inode num 0 */
+#define VMUFAT_ZEROBLOCK 32768
+#define VMU_BLK_SZ 512
+#define VMUFAT_MAGIC 0x55555555
+
+#define FATFILEEND	0xFFFA
+#define FATEMPTY	0xFFFC
+#define DIRRECLEN	0x20
+#define DIRRECBLK	0x10
+
+static struct kmem_cache *vmufat_inode_cachep;
+static struct kmem_cache *vmufat_blist_cachep;
+static const struct inode_operations vmufat_inode_operations;
+static const struct file_operations vmufat_file_operations;
+static const struct address_space_operations vmufat_address_space_operations;
+static const struct file_operations vmufat_file_dir_operations;
+static const struct super_operations vmufat_super_operations;
+
+static struct inode *vmufat_get_inode(struct super_block *sb, long ino);
+static int vmufat_list_blocks(struct inode *in);
+
+struct memcard {
+	long sb_bnum;
+	long fat_bnum;
+	long fat_len;
+	long dir_bnum;
+	long dir_len;
+	long numblocks;
+};
+
+struct vmufat_block_list {
+	struct list_head b_list;
+	int bno;
+};
+
+struct vmufat_inode {
+	struct vmufat_block_list blocks;
+	int nblcks;
+	struct inode vfs_inode;
+};
+
+static struct vmufat_inode *VMUFAT_I(struct inode *in)
+{
+	return container_of(in, struct vmufat_inode, vfs_inode);
+}
+
+struct vmufat_file_info {
+	u8 ftype;
+	u8 copy_pro;
+	u16 fblk;
+	char fname[VMUFATNAMELEN];
+};
+
+static inline int vmufat_index(int fno)
+{
+	return (fno % DIRRECBLK) * DIRRECLEN;
+}
+
+static inline int vmufat_index_16(int fno)
+{
+	return (fno % DIRRECBLK) * DIRECLEN / 2;
+}
+
+/* VMU hardware is flaky, so let's compensate for that
+ * without losing hardare independence -
+ * as it is likely to be where this filesystem is used
+ */
+static inline struct buffer_head *vmufat_sb_bread(struct super_block *sb,
+	sector_t block)
+{
+	struct buffer_head *bh;
+	bh = sb_bread(sb, block);
+	if (bh)
+		return bh;
+	return sb_bread(sb, block);
+}
+
+/* Linear day numbers of the respective 1sts in non-leap years. */
+static int day_n[] +    {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
+
+static struct dentry *vmufat_inode_lookup(struct inode *in, struct dentry *dent,
+	struct nameidata *nd)
+{
+	struct super_block *sb;
+	struct memcard *vmudetails;
+	struct buffer_head *bh;
+	struct inode *ino;
+	char name[VMUFAT_NAMELEN];
+	long blck_read;
+	int error = 0, fno = 0;
+
+	if (dent->d_name.len > VMUFAT_NAMELEN) {
+		error = -ENAMETOOLONG;
+		goto out;
+	}
+
+	sb = in->i_sb;
+	vmudetails = sb->s_fs_info;
+	blck_read = vmudetails->dir_bnum;
+
+	bh = vmufat_sb_bread(sb, blck_read);
+	if (!bh) {
+		error = -EIO;
+		goto out;
+	}
+
+	do {
+		/* Have we got a file? */
+		if (bh->b_data[vmufat_index(fno)] = 0)
+			goto next;
+
+		/* get file name */
+		memcpy(name,
+		       bh->b_data + 4 + vmufat_index(fno), VMUFAT_NAMELEN);
+		/* do names match ?*/
+		if (memcmp(dent->d_name.name, name, dent->d_name.len) = 0) {
+			/* read the inode number from the directory */
+			ino = vmufat_get_inode(sb,
+				le16_to_cpu(((u16 *) bh->b_data)
+					[1 + vmufat_index_16(fno)]));
+			if (!ino) {
+				error = -EACCES;
+				goto release_bh;
+			}
+			if (IS_ERR(ino)) {
+				error = PTR_ERR(ino);
+				goto release_bh;
+			}
+			/* return the entry */
+			d_add(dent, ino);
+			goto release_bh;
+		}
+next:
+		/* did not match, so try the next file */
+		fno++;
+		/* do we need to move to the next block in the directory? */
+		if (fno >= 0x10) {
+			fno = 0;
+			blck_read--;
+			if (blck_read <+				vmudetails->dir_bnum - vmudetails->dir_len) {
+				d_add(dent, NULL);
+				break;
+			}
+			brelse(bh);
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh) {
+				error = -EIO;
+				goto out;
+			}
+		}
+	} while (1);
+
+release_bh:
+	brelse(bh);
+out:
+	return ERR_PTR(error);
+}
+
+/*
+ * Find a free block in the FAT and mark it
+ * as the end of a file
+ */
+static int vmufat_find_free(struct super_block *sb)
+{
+	struct memcard *vmudetails = sb->s_fs_info;
+	int nextblock, x;
+	u16 fatdata;
+	struct buffer_head *bh_fat;
+	int error = 0;
+
+	nextblock = vmudetails->fat_bnum + vmudetails->fat_len - 1;
+	x = VMU_BLK_SZ;
+	bh_fat +	    vmufat_sb_bread(sb, nextblock);
+	if (!bh_fat) {
+		error = -EIO;
+		goto fail;
+	}
+
+	do {
+		fatdata = ((u16 *) bh_fat->b_data)[x];
+		if (fatdata = FATEMPTY)
+			break;	/*empty block */
+		if (--x < 0) {
+			put_bh(bh_fat);
+			if (--nextblock >= vmudetails->fat_bnum) {
+				x = VMU_BLK_SZ;
+				bh_fat = vmufat_sb_bread(sb, nextblock);
+				if (!bh_fat) {
+					error = -EIO;
+					goto fail;
+				}
+			} else
+				break;
+		}
+	} while (1);
+
+	if (nextblock < vmudetails->fat_bnum) {
+		printk(KERN_ERR "VMUFAT: device is full\n");
+		error = -ENOSPC;
+		put_bh(bh_fat);
+		goto fail;
+	}
+	put_bh(bh_fat);
+	return  x + (nextblock - vmudetails->fat_bnum) * VMU_BLK_SZ;
+
+fail:
+	return error;
+}
+
+/* read the FAT for a given block */
+static u16 vmufat_get_fat(struct super_block *sb, long block)
+{
+	struct memcard *vmudetails = sb->s_fs_info;
+	struct buffer_head *bh;
+	int offset;
+	u16 block_content;
+
+	offset = block/(VMU_BLK_SZ/2);
+	if (offset >= vmudetails->fat_len)
+		return 0xFFFE;
+
+	bh = vmufat_sb_bread(sb, offset + 1 +
+		vmudetails->fat_bnum - vmudetails->fat_len);
+	if (!bh)
+		return 0xFFFF;
+
+	block_content = ((u16 *)bh->b_data)[block % (VMU_BLK_SZ / 2)];
+	put_bh(bh);
+	return block_content;
+}
+
+/* set the FAT for a given block */
+static int vmufat_set_fat(struct super_block *sb, long block, u16 set)
+{
+	struct memcard *vmudetails = sb->s_fs_info;
+	struct buffer_head *bh;
+	int offset;
+
+	offset = block/(VMU_BLK_SZ/2);
+	if (offset >= vmudetails->fat_len)
+		return -EINVAL;
+
+	bh = vmufat_sb_bread(sb, offset + 1 +
+		vmudetails->fat_bnum - vmudetails->fat_len);
+	if (!bh)
+		return -EIO;
+
+	((u16 *) bh->b_data)[block % (VMU_BLK_SZ / 2)] = set;
+	mark_buffer_dirty(bh);
+	put_bh(bh);
+	return 0;
+}
+
+static int vmufat_inode_create(struct inode *dir, struct dentry *de,
+		int imode, struct nameidata *nd)
+{
+	/* Create an inode */
+	int x = 0, y, z, error = 0, q;
+	long blck_read;
+	struct inode *inode;
+	struct super_block *sb;
+	struct memcard *vmudetails;
+	struct buffer_head *bh_fat = NULL, *bh;
+	unsigned long unix_date;
+	int year, day, nl_day, month;	/*inspired by FAT driver */
+	u8 century, u8year;
+
+	if (de->d_name.len > VMUFAT_NAMELEN)
+		return -ENAMETOOLONG;
+
+	sb = dir->i_sb;
+	vmudetails = sb->s_fs_info;
+
+	inode = new_inode(sb);
+	if (!inode) {
+		error = -ENOSPC;
+		goto out;
+	}
+
+	/* Walk through blocks looking for place to write
+	* Is this an executible file? */
+	if (imode & 73) {	/*Octal 111 */
+		inode->i_ino = VMUFAT_ZEROBLOCK;
+		/* But this already allocated? */
+		if (vmufat_get_fat(sb, 0) != FATEMPTY) {
+			printk(KERN_ERR
+				"VMUFAT: cannot write executible file to"
+				" filesystem - block 0 already allocated.\n");
+			error = -ENOSPC;
+			goto clean_inode;
+		}
+		q = 0;
+	} else {
+		q = vmufat_find_free(sb);
+		if (q < 0) {
+			error = q;
+			goto clean_inode;
+		}
+		inode->i_ino = q;
+	}
+
+	error = vmufat_set_fat(sb, q, FATFILEEND);
+	if (error)
+		goto clean_inode;
+
+	inode->i_uid = 0;
+	inode->i_gid = 0;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_mode = imode;
+	inode->i_blocks = 1;
+	inode->i_sb = sb;
+	insert_inode_hash(inode);
+	inode->i_op = &vmufat_inode_operations;
+	inode->i_fop = &vmufat_file_operations;
+	inode->i_mapping->a_ops = &vmufat_address_space_operations;
+
+	/* Write to the directory
+	* Now search for space for the directory entry */
+	blck_read = vmudetails->dir_bnum;
+	bh = vmufat_sb_bread(sb, blck_read);
+	if (!bh) {
+		error = -EIO;
+		goto clean_inode;
+	}
+
+	for (y = 0; y < (vmudetails->dir_len * 0x10); y++) {
+		if ((y / 0x10) > (vmudetails->dir_bnum - blck_read)) {
+			brelse(bh);
+			blck_read--;
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh) {
+				error = -EIO;
+				goto clean_fat;
+			}
+		}
+		if (((bh->b_data)[vmufat_index(y)]) = 0)
+			break;
+	}
+	/* Have the directory entry
+	 * so now update it */
+	z = vmufat_index(y);
+	if (inode->i_ino != VMUFAT_ZEROBLOCK)
+		bh->b_data[z] = 0x33;	/* data file */
+	else
+		bh->b_data[z] = 0xcc;
+
+	if ((bh->b_data[z + 1] != (char) 0x00) &&
+		(bh->b_data[z + 1] != (char) 0xff))
+		bh->b_data[z + 1] = (char) 0x00;
+
+	if (inode->i_ino != VMUFAT_ZEROBLOCK) {
+		((u16 *) bh->b_data)[z / 2 + 1] +		    cpu_to_le16(inode->i_ino);
+		((u16 *) bh->b_data)[z / 2 + 0x0D] = 0;
+	} else {
+		((u16 *) bh->b_data)[z / 2 + 1] = 0;
+		((u16 *) bh->b_data)[z / 2 + 0x0D] = 1;
+	}
+
+	/* Name */
+	memset((char *) (bh->b_data + z + 0x04), '\0', 0x0C);
+	memcpy((char *) (bh->b_data + z + 0x04), ((de->d_name).name),
+		de->d_name.len);
+
+	/* BCD timestamp it */
+	unix_date = CURRENT_TIME.tv_sec;
+	day = unix_date / 86400 - 3652;
+	year = day / 365;
+
+	if ((year + 3) / 4 + 365 * year > day)
+		year--;
+
+	day -= (year + 3) / 4 + 365 * year;
+	if (day = 59 && !(year & 3)) {
+		nl_day = day;
+		month = 2;
+	} else {
+		nl_day = (year & 3) || day <= 59 ? day : day - 1;
+		for (month = 0; month < 12; month++)
+			if (day_n[month] > nl_day)
+				break;
+	}
+
+	century = 19;
+	if (year > 19)
+		century = 20;
+
+	bh->b_data[z + 0x10] = bin2bcd(century);
+	u8year = year + 80;
+	if (u8year > 99)
+		u8year = u8year - 100;
+
+	bh->b_data[z + 0x11] = bin2bcd(u8year);
+	bh->b_data[z + 0x12] = bin2bcd(month);
+	bh->b_data[z + 0x13] +	    bin2bcd(day - day_n[month - 1] + 1);
+	bh->b_data[z + 0x14] +	    bin2bcd((unix_date / 3600) % 24);
+	bh->b_data[z + 0x15] = bin2bcd((unix_date / 60) % 60);
+	bh->b_data[z + 0x16] = bin2bcd(unix_date % 60);
+
+	((u16 *) bh->b_data)[z / 2 + 0x0C] +	    cpu_to_le16(inode->i_blocks);
+
+	inode->i_mtime.tv_sec = unix_date;
+	mark_buffer_dirty(bh);
+	brelse(bh);
+
+	error = vmufat_list_blocks(inode);
+	if (error)
+		goto clean_fat;
+
+	d_instantiate(de, inode);
+	brelse(bh_fat);
+	return error;
+
+clean_fat:
+	((u16 *)bh_fat->b_data)[x] = FATEMPTY;
+	mark_buffer_dirty(bh_fat);
+	brelse(bh_fat);
+clean_inode:
+	iput(inode);
+out:
+	return error;
+}
+
+static int vmufat_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	int filenamelen, i, error = 0;
+	struct vmufat_file_info *saved_file = NULL;
+	struct dentry *dentry = filp->f_dentry;
+	struct inode *inode = dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
+	struct memcard *vmudetails = sb->s_fs_info;
+	struct buffer_head *bh;
+
+	int blck_read = vmudetails->dir_bnum;
+	bh = vmufat_sb_bread(sb, blck_read);
+	if (!bh) {
+		error = -EIO;
+		goto out;
+	}
+
+	i = filp->f_pos;
+
+	/* handle . for this directory and .. for parent */
+	switch ((unsigned int) filp->f_pos) {
+	case 0:
+		if (filldir(dirent, ".", 1, i++, inode->i_ino, DT_DIR) < 0)
+			goto finish;
+
+		filp->f_pos++;
+	case 1:
+		if (filldir(dirent, "..", 2, i++,
+			    dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
+			goto finish;
+
+		filp->f_pos++;
+	default:
+		break;
+	}
+
+	/* trap reading beyond the end of the directory */
+	if ((i - 2) > (vmudetails->dir_len * 0x10)) {
+		error = -EINVAL;
+		goto release_bh;
+	}
+
+	saved_file +	    kmalloc(sizeof(struct vmufat_file_info), GFP_KERNEL);
+	if (!saved_file) {
+		error = -ENOMEM;
+		goto release_bh;
+	}
+
+	do {
+		if ((i - 2) / 0x10 > (vmudetails->dir_bnum - blck_read)) {
+			/* move to next block in directory */
+			blck_read--;
+			if (vmudetails->dir_bnum - vmudetails->dir_len <+				blck_read)
+				break;
+			brelse(bh);
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh) {
+				kfree(saved_file);
+				error = -EIO;
+				goto out;
+			}
+		}
+
+		saved_file->ftype = bh->b_data[vmufat_index(i - 2)];
+
+		if (saved_file->ftype = 0)
+			break;
+
+		saved_file->fblk +		    le16_to_cpu(((u16 *) bh->b_data)[1 +
+			vmufat_index_16(i - 2)]);
+		if (saved_file->fblk = 0)
+			saved_file->fblk = VMUFAT_ZEROBLOCK;
+
+		memcpy(saved_file->fname,
+		       bh->b_data + 4 + vmufat_index(i - 2), VMUFAT_NAMELEN);
+		filenamelen = strlen(saved_file->fname);
+		if (filenamelen > VMUFAT_NAMELEN)
+			filenamelen = VMUFAT_NAMELEN;
+		if (filldir
+		    (dirent, saved_file->fname, filenamelen, i++,
+		     saved_file->fblk, DT_REG) < 0) {
+			goto finish;
+		}
+
+		filp->f_pos++;
+	} while (1);
+
+finish:
+	kfree(saved_file);
+release_bh:
+	brelse(bh);
+out:
+	return error;
+}
+
+
+
+static long vmufat_get_date(struct buffer_head *bh, int offset)
+{
+	int century, year, month, day, hour, minute, second;
+
+	century = bcd2bin(bh->b_data[offset++]);
+	year = bcd2bin(bh->b_data[offset++]);
+	month = bcd2bin(bh->b_data[offset++]);
+	day = bcd2bin(bh->b_data[offset++]);
+	hour = bcd2bin(bh->b_data[offset++]);
+	minute = bcd2bin(bh->b_data[offset++]);
+	second = bcd2bin(bh->b_data[offset]);
+
+	return 	mktime(century * 100 + year, month, day, hour, minute,
+			second);
+}
+
+static struct inode *vmufat_alloc_inode(struct super_block *sb)
+{
+	struct vmufat_inode *vi = kmem_cache_alloc(vmufat_inode_cachep,
+		GFP_KERNEL);
+
+	if (!vi)
+		return NULL;
+	INIT_LIST_HEAD(&vi->blocks.b_list);
+	return &vi->vfs_inode;
+}
+
+static void vmufat_destroy_inode(struct inode *in)
+{
+	struct vmufat_inode *vi = VMUFAT_I(in);
+	struct vmufat_block_list *vb;
+	struct list_head *iter, *iter2;
+
+	list_for_each_safe(iter, iter2, &vi->blocks.b_list) {
+		vb = list_entry(iter, struct vmufat_block_list, b_list);
+		list_del(iter);
+		kmem_cache_free(vmufat_blist_cachep, vb);
+	}
+	kmem_cache_free(vmufat_inode_cachep, vi);
+}
+
+static int vmufat_list_blocks(struct inode *in)
+{
+	struct vmufat_inode *vi = VMUFAT_I(in);
+	struct super_block *sb = in->i_sb;
+	long nextblock;
+	long ino = in->i_ino;
+	int fat_seg;
+	struct buffer_head *bh;
+	struct memcard *vmudetails;
+	int error;
+	struct list_head *iter, *iter2;
+	struct vmufat_block_list *vbl, *nvbl;
+	u16 fatdata;
+
+	vmudetails = sb->s_fs_info;
+	nextblock = ino;
+	fat_seg = nextblock / (sb->s_blocksize / 2);
+	bh = vmufat_sb_bread(sb, vmudetails->fat_bnum -
+		(vmudetails->fat_len - 1) + fat_seg);
+	if (!bh) {
+		error = -EIO;
+		goto out;
+	}
+
+	/* Delete any previous list of blocks */
+	list_for_each_safe(iter, iter2, &vi->blocks.b_list) {
+		vbl = list_entry(iter, struct vmufat_block_list, b_list);
+		list_del(iter);
+		kmem_cache_free(vmufat_blist_cachep, vbl);
+	}
+	vi->nblcks = 0;
+	do {
+		vbl = kmem_cache_alloc(vmufat_blist_cachep,
+			GFP_KERNEL);
+		if (!vbl) {
+			error = -ENOMEM;
+			goto unwind_out;
+		}
+		INIT_LIST_HEAD(&vbl->b_list);
+		vbl->bno = nextblock;
+		list_add_tail(&vbl->b_list, &vi->blocks.b_list);
+		vi->nblcks++;
+
+		/* Find next block in the FAT - if there is one */
+		fatdata = ((u16 *) bh->b_data)
+			[nextblock % (sb->s_blocksize / 2)];
+		if (fatdata = FATEMPTY) {
+			printk(KERN_WARNING "VMUFAT: FAT table appears to have"
+				" been corrupted.\n");
+			error = -EIO;
+			goto unwind_out;
+		}
+		if (fatdata = FATFILEEND)
+			break;	/*end of file */
+		if (fatdata / (sb->s_blocksize / 2) != fat_seg) {
+			brelse(bh);
+			fat_seg = fatdata / (sb->s_blocksize / 2);
+			bh = vmufat_sb_bread(sb, vmudetails->fat_bnum -
+				(vmudetails->fat_len - 1) + fat_seg);
+			if (!bh) {
+				error = -ENOMEM;
+				goto unwind_out;
+			}
+		}
+		nextblock = fatdata;
+	} while (1);
+	brelse(bh);
+	return 0;
+
+unwind_out:
+	list_for_each_entry_safe(vbl, nvbl, &vi->blocks.b_list, b_list) {
+		list_del_init(&vbl->b_list);
+		kmem_cache_free(vmufat_blist_cachep, vbl);
+	}
+out:
+	return error;
+}
+
+static struct inode *vmufat_get_inode(struct super_block *sb, long ino)
+{
+	struct buffer_head *bh;
+	int error, blck_read, y, z;
+	struct inode *inode = iget_locked(sb, ino);
+	struct memcard *vmudetails = sb->s_fs_info;
+	long superblock_bno = vmudetails->sb_bnum;
+
+	if (inode && (inode->i_state & I_NEW)) {
+		inode->i_uid = 0;
+		inode->i_gid = 0;
+		inode->i_mode &= ~S_IFMT;
+		if (inode->i_ino = superblock_bno) {
+			bh = vmufat_sb_bread(sb, inode->i_ino);
+			if (!bh) {
+				error = -EIO;
+				goto failed;
+			}
+			inode->i_ctime.tv_sec = inode->i_mtime.tv_sec +				vmufat_get_date(bh, 0x30);
+
+			/* Mark as a directory */
+			inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
+
+			inode->i_op = &vmufat_inode_operations;
+			inode->i_fop = &vmufat_file_dir_operations;
+		} else {
+			blck_read = vmudetails->dir_bnum;
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh) {
+				error = -EIO;
+				goto failed;
+			}
+
+			/* Mark file as regular type */
+			inode->i_mode = S_IFREG;
+
+			/* Scan through the directory to find matching file */
+			for (y = 0; y < vmudetails->numblocks; y++) {
+				if ((y / 0x10) >
+				    (vmudetails->dir_bnum - blck_read)) {
+					brelse(bh);
+					blck_read--;
+					bh = vmufat_sb_bread(sb, blck_read);
+					if (!bh) {
+						error = -EIO;
+						goto failed;
+					}
+				}
+				if (le16_to_cpu
+				    (((u16 *) bh->b_data)[(y % 0x10) * 0x10 +
+						    0x01]) = ino)
+					break;
+				}
+
+				if (y >= vmudetails->numblocks) {
+					brelse(bh);
+					printk(KERN_INFO
+						"vmufat: could not find this "
+						"file on filesystem\n");
+				error = -ENOENT;
+				goto failed;
+			}
+
+			/* identified the correct directory entry */
+			z = vmufat_index(y);
+			inode->i_ctime.tv_sec = inode->i_mtime.tv_sec +				vmufat_get_date(bh, z + 0x10);
+
+			/* Execute if a game, write if not copy protected */
+			inode->i_mode &= ~(S_IWUGO | S_IXUGO);
+			inode->i_mode |= S_IRUGO;
+
+			/* Mode - is it write protected? */
+			if ((((u8 *) bh->b_data)[0x01 + z] =
+			     0x00) & ~(sb->s_flags & MS_RDONLY))
+				inode->i_mode |= S_IWUGO;
+			/* Is file executible - ie a game */
+			if ((((u8 *) bh->b_data)[z] =
+			     0xcc) & ~(sb->s_flags & MS_NOEXEC))
+				inode->i_mode |= S_IXUGO;
+
+			inode->i_fop = &vmufat_file_operations;
+
+			inode->i_blocks +			    le16_to_cpu(((u16 *) bh->b_data)
+				[vmufat_index_16(y) + 0x0C]);
+			inode->i_size = inode->i_blocks * sb->s_blocksize;
+
+			inode->i_mapping->a_ops +				&vmufat_address_space_operations;
+			inode->i_op = &vmufat_inode_operations;
+			inode->i_fop = &vmufat_file_operations;
+			error = vmufat_list_blocks(inode);
+			if (error)
+				goto failed;
+		}
+		inode->i_atime = CURRENT_TIME;
+		unlock_new_inode(inode);
+	}
+
+	return inode;
+
+failed:
+	iget_failed(inode);
+	return ERR_PTR(error);
+}
+
+static void vmufat_put_super(struct super_block *sb)
+{
+	sb->s_dev = 0;
+	kfree(sb->s_fs_info);
+}
+
+static int vmufat_scan(struct super_block *sb, struct kstatfs *buf)
+{
+	int error = 0;
+	int free = 0;
+	int x;
+	u16 fatdata;
+	struct buffer_head *bh_fat;
+	struct memcard *vmudetails = sb->s_fs_info;
+	long nextblock;
+
+	/* Look through the FAT */
+	nextblock = vmudetails->fat_bnum + vmudetails->fat_len - 1;
+	x = sb->s_blocksize;
+	bh_fat = vmufat_sb_bread(sb, nextblock);
+	if (!bh_fat) {
+		error = -EIO;
+		goto out;
+	}
+
+	do {
+		fatdata = ((u16 *) bh_fat->b_data)[x];
+		if (fatdata = FATEMPTY)
+			free++;
+		if (--x < 0) {
+			brelse(bh_fat);
+			if (--nextblock >= vmudetails->fat_bnum) {
+				x = sb->s_blocksize;
+				bh_fat = vmufat_sb_bread(sb, nextblock);
+				if (!bh_fat) {
+					error = -EIO;
+					goto out;
+				}
+			} else
+				break;
+		}
+	} while (1);
+
+	buf->f_bfree = free;
+	buf->f_bavail = free;
+	buf->f_blocks = vmudetails->numblocks;
+
+out:
+	return error;
+}
+
+static int vmufat_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	int error;
+
+	error = vmufat_scan(sb, buf);
+	if (error)
+		return error;
+	buf->f_type = VMUFAT_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_namelen = VMUFAT_NAMELEN;
+
+	return 0;
+}
+
+/*
+ * Delete inode by marking space as free in FAT
+ * no need to waste time and effort by actually
+ * wiping underlying data on media
+ */
+static void vmufat_delete_inode(struct inode *in)
+{
+	struct buffer_head *bh, *bh_old;
+	struct super_block *sb;
+	struct memcard *vmudetails;
+	int z, y, x, w, v, blck_read, error;
+	u16 nextblock, fatdata;
+
+	if (in->i_ino = VMUFAT_ZEROBLOCK)
+		in->i_ino = 0;
+	sb = in->i_sb;
+	vmudetails = sb->s_fs_info;
+	if (in->i_ino > vmudetails->fat_len * sb->s_blocksize / 2) {
+		printk(KERN_ERR "vmufat: attempting to delete"
+			"inode beyond device size");
+		return;
+	}
+
+	/* Seek start of file and wander through FAT
+ 	 * Marking the blocks as unallocated */
+	nextblock = in->i_ino;
+	do {
+		fatdata = vmufat_get_fat(sb, nextblock);
+		error = vmufat_set_fat(sb, nextblock, FATEMPTY);
+		if (error)
+			goto failure;
+		if (fatdata = FATFILEEND)
+			break;
+		nextblock = fatdata;
+	} while (1);
+
+	/* Now clean the directory entry
+	 * Have to wander through this
+	 * to find the appropriate entry */
+	blck_read = vmudetails->dir_bnum;
+	bh = vmufat_sb_bread(sb, blck_read);
+	if (!bh)
+		goto failure;
+
+	for (y = 0; y < (vmudetails->dir_len * 0x10); y++) {
+		if ((y / 0x10) > (vmudetails->dir_bnum - blck_read)) {
+			brelse(bh);
+			blck_read--;
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh)
+				goto failure;
+		}
+		if (le16_to_cpu
+		    (((u16 *) bh->b_data)[(y % 0x10) * 0x10 +
+					    0x01]) = in->i_ino)
+			break;
+	}
+
+	/* Found directory entry - so NULL it now */
+	w = vmufat_index_16(y);
+	for (z = 0; z < 0x10; z++)
+		((u16 *) bh->b_data)[w + z] = 0;
+	mark_buffer_dirty(bh);
+	/* Replace it with another entry - if one exists */
+	x = y;
+	for (y = x + 1; y < (vmudetails->dir_len * 0x10); y++) {
+		if ((y / 0x10) > (vmudetails->dir_bnum - blck_read)) {
+			brelse(bh);
+			blck_read--;
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh)
+				return;
+		}
+		/* look for the end of entries in the directory */
+		if (bh->b_data[vmufat_index(y)] = 0) {
+			y--;
+			if (y = x)
+				break;	/* At the end in any case */
+			brelse(bh);
+
+			/* force read of correct block */
+			bh = vmufat_sb_bread(sb, vmudetails->dir_bnum -
+				y / 0x10);
+			if (!bh)
+				goto failure;
+			bh_old +			    vmufat_sb_bread(sb, vmudetails->dir_bnum -
+				x / 0x10);
+			if (!bh_old) {
+				brelse(bh);
+				goto failure;
+			}
+
+			/*
+ 			 * Copy final directory entry into space created
+			 * by the deletion of the inode
+			 */
+			w = vmufat_index_16(x);
+			v = vmufat_index_16(y);
+			for (z = 0; z < 0x10; z++) {
+				((u16 *) bh_old->b_data)[w + z] +					((u16 *) bh->b_data)[v + z];
+				((u16 *) bh->b_data)[v + z] = 0;
+			}
+			mark_buffer_dirty(bh);
+			if (x/0x10 != y/0x10)
+				mark_buffer_dirty(bh_old);
+			brelse(bh_old);
+			break;
+		}
+	}
+
+	brelse(bh);
+	return;
+
+failure:
+	printk(KERN_ERR "vmufat: Failure to read device,"
+		" could not delete inode - filesystem may be damaged\n");
+	return;
+}
+
+/*
+ * vmufat_unlink - delete a file pointed to
+ * by the dentry (only one directory in a
+ * vmufat fs so safe to ignore the inode
+ * upplied here
+ */
+static int vmufat_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *in;
+
+	in = dentry->d_inode;
+	if (!in)
+		return -EIO;
+	vmufat_delete_inode(in);
+	return 0;
+}
+
+static int vmufat_get_block(struct inode *inode, sector_t iblock,
+	struct buffer_head *bh_result, int create)
+{
+	struct vmufat_inode *vin = VMUFAT_I(inode);
+	struct vmufat_block_list *vlist = &vin->blocks;
+	struct vmufat_block_list *vblk;
+	struct super_block *sb = inode->i_sb;
+	int cural;
+	int finblk, nxtblk, exeblk;
+	struct list_head *iter;
+	sector_t cntdwn = iblock;
+	sector_t phys;
+	int error = -EINVAL;
+
+	/* quick sanity check */
+	if (vin->nblcks <= 0)
+		goto out;
+	if (iblock < vin->nblcks) {
+		/* block is already here so read it into the buffer head */
+		list_for_each(iter, &vlist->b_list) {
+			if (cntdwn-- = 0)
+				break;
+		}
+		vblk = list_entry(iter, struct vmufat_block_list, b_list);
+		clear_buffer_new(bh_result);
+		error = 0;
+		phys = vblk->bno;
+		goto got_it;
+	}
+	if (!create) {
+		error = -EINVAL;
+		goto out;
+	}
+	/*
+	 * check not looking for a block too far
+	 * beyond the end of the existing file
+	 */
+	if (iblock > vin->nblcks) {
+		error = -EINVAL;
+		goto out;
+	}
+
+	/* if looking for a block that is not current - allocate it*/
+	cural = vin->nblcks;
+	list_for_each(iter, &vlist->b_list) {
+		if (cural-- = 1)
+			break;
+	}
+	vblk = list_entry(iter, struct vmufat_block_list, b_list);
+	finblk = vblk->bno;
+
+	/* Exec files have to be linear */
+	if (inode->i_ino = 0) {
+		exeblk = vmufat_get_fat(sb, finblk + 1);
+		if (exeblk != FATEMPTY) {
+			printk(KERN_WARNING "Cannot allocate linear space "
+				"needed for executible\n");
+			error = -ENOSPC;
+			goto out;
+		}
+		nxtblk = finblk + 1;
+	} else {
+		nxtblk = vmufat_find_free(sb);
+		if (nxtblk < 0) {
+			error = nxtblk;
+			goto out;
+		}
+	}
+	error = vmufat_set_fat(sb, finblk, nxtblk);
+	if (error)
+		goto out;
+	error = vmufat_set_fat(sb, nxtblk, FATFILEEND);
+	if (error)
+		goto out;
+	error = vmufat_list_blocks(inode);
+	mark_inode_dirty(inode);
+	if (error)
+		goto out;
+	set_buffer_new(bh_result);
+	phys = nxtblk;
+	error = 0;
+got_it:
+	map_bh(bh_result, sb, phys);
+out:
+	return error;
+}
+
+static int vmufat_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, vmufat_get_block, wbc);
+}
+
+static int vmufat_write_begin(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, unsigned flags,
+		struct page **pagep, void **fsdata)
+{
+	*pagep = NULL;
+	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+		vmufat_get_block);
+}
+
+static int vmufat_readpage(struct file *file, struct page *page)
+{
+	return block_read_full_page(page, vmufat_get_block);
+}
+
+/*
+ * There are no inodes on the medium - vmufat_write_inode
+ * updates the directory entry
+ */
+static int vmufat_write_inode(struct inode *in, int wait)
+{
+	struct buffer_head *bh;
+	__u8 century, u8year;
+	unsigned long inode_num;
+	int y, blck_read, z;
+	unsigned long unix_date;
+	int year, day, nl_day, month;
+	struct super_block *sb = in->i_sb;
+	struct memcard *vmudetails +	    ((struct memcard *) sb->s_fs_info);
+
+	/* As most real world devices are flash
+ 	 * we won't update the superblock every
+ 	 * time we change something else on the fs
+ 	 * - it is ugly but a sensible compromise
+ 	 */
+	if (in->i_ino = vmudetails->sb_bnum)
+		return 0;
+
+	if (in->i_ino = VMUFAT_ZEROBLOCK)
+		inode_num = 0;
+	else
+		inode_num = in->i_ino;
+
+	/* update the directory and inode details */
+	/* Now search for the directory entry */
+	blck_read = vmudetails->dir_bnum;
+	bh = vmufat_sb_bread(sb, blck_read);
+	if (!bh)
+		return -EIO;
+
+	for (y = 0; y < vmudetails->numblocks; y++) {
+		if ((y / 0x10) > (vmudetails->dir_bnum - blck_read)) {
+			brelse(bh);
+			blck_read--;
+			bh = vmufat_sb_bread(sb, blck_read);
+			if (!bh)
+				return -EIO;
+		}
+		if (le16_to_cpu
+		    (((__u16 *) bh->b_data)[vmufat_index_16(y) +
+					    0x01]) = inode_num)
+			break;
+	}
+	/* Have the directory entry
+	 * so now update it */
+	z = (y % 0x10) * 0x20;
+	if (inode_num != 0)
+		bh->b_data[z] = 0x33;	/* data file */
+	else
+		bh->b_data[z] = 0xcc;
+	if (bh->b_data[z + 1] !=  0
+	    && bh->b_data[z + 1] != (char) 0xff)
+		bh->b_data[z + 1] = 0;
+	((__u16 *) bh->b_data)[z / 2 + 1] = cpu_to_le16(inode_num);
+
+	/* BCD timestamp it */
+	unix_date = CURRENT_TIME.tv_sec;
+	day = unix_date / 86400 - 3652;
+	year = day / 365;
+	if ((year + 3) / 4 + 365 * year > day)
+		year--;
+	day -= (year + 3) / 4 + 365 * year;
+	if (day = 59 && !(year & 3)) {
+		nl_day = day;
+		month = 2;
+	} else {
+		nl_day = (year & 3) || day <= 59 ? day : day - 1;
+		for (month = 0; month < 12; month++)
+			if (day_n[month] > nl_day)
+				break;
+	}
+
+	century = 19;
+	if (year > 19)
+		century = 20;
+	bh->b_data[z + 0x10] = bin2bcd(century);
+	u8year = year + 80;
+	if (u8year > 99)
+		u8year = u8year - 100;
+	bh->b_data[z + 0x11] = bin2bcd(u8year);
+	bh->b_data[z + 0x12] = bin2bcd(month);
+	bh->b_data[z + 0x13] = bin2bcd(day - day_n[month - 1] + 1);
+	bh->b_data[z + 0x14] = bin2bcd((unix_date / 3600) % 24);
+	bh->b_data[z + 0x15] = bin2bcd((unix_date / 60) % 60);
+	bh->b_data[z + 0x16] = bin2bcd(unix_date % 60);
+
+	((__u16 *) bh->b_data)[z / 2 + 0x0C] = cpu_to_le16(in->i_blocks);
+	if (inode_num != 0)
+		((__u16 *) bh->b_data)[z / 2 + 0x0D] = 0;
+	else /* game */
+		((__u16 *) bh->b_data)[z / 2 + 0x0D] = cpu_to_le16(1);
+	in->i_mtime.tv_sec = unix_date;
+	mark_buffer_dirty(bh);
+	brelse(bh);
+	return 0;
+}
+
+static int check_sb_format(struct buffer_head *bh)
+{
+	u32 s_magic = VMUFAT_MAGIC;
+
+	if (!(((u32 *) bh->b_data)[0] = s_magic &&
+		((u32 *) bh->b_data)[1] = s_magic &&
+		((u32 *) bh->b_data)[2] = s_magic &&
+		((u32 *) bh->b_data)[3] = s_magic))
+		return 0;
+	else
+		return 1;
+}
+
+static void init_once(void *foo)
+{
+	struct vmufat_inode *vi = foo;
+
+	vi->nblcks = 0;
+	inode_init_once(&vi->vfs_inode);
+}
+
+
+static int init_inodecache(void)
+{
+	vmufat_inode_cachep = kmem_cache_create("vmufat_inode_cache",
+		sizeof(struct vmufat_inode), 0,
+			SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, init_once);
+	if (!vmufat_inode_cachep)
+		return -ENOMEM;
+
+	vmufat_blist_cachep = kmem_cache_create("vmufat_blocklist_cache",
+		sizeof(struct vmufat_block_list), 0, SLAB_MEM_SPREAD, NULL);
+	if (!vmufat_blist_cachep) {
+		kmem_cache_destroy(vmufat_inode_cachep);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void destroy_inodecache(void)
+{
+	kmem_cache_destroy(vmufat_blist_cachep);
+	kmem_cache_destroy(vmufat_inode_cachep);
+}
+
+static int vmufat_fill_super(struct super_block *sb,
+					    void *data, int silent)
+{
+	/*Search for the superblock - assuming likely sizes are
+	* 128, 256, 512 and 1024 blocks */
+
+	struct buffer_head *bh;
+	struct memcard *vmudata;
+	int z;
+	struct inode *root_i;
+	int ret = -EINVAL;
+
+	sb_set_blocksize(sb, VMU_BLK_SZ);
+
+	/* Have to try lowest number first to avoid oops */
+	for (z = 128; z < 1024; z = z * 2) {
+		bh = vmufat_sb_bread(sb, z - 1);
+		if (!bh) {
+			ret = -EIO;
+			goto out;
+		}
+		if (check_sb_format(bh))
+			break;
+		brelse(bh);
+		if (z = 1024) {	/* failed */
+			printk(KERN_ERR
+				"vmufat: attempted to mount non vmufat medium"
+				" as vmufat\n");
+			goto out;
+		}
+	}
+	/* Store this data in the super block */
+
+	vmudata = kmalloc(sizeof(struct memcard), GFP_KERNEL);
+	if (!vmudata) {
+		ret = -ENOMEM;
+		goto freebh_out;
+	}
+
+	/* user blocks */
+	vmudata->sb_bnum = z - 1;
+	vmudata->fat_bnum = le16_to_cpu(((u16 *) bh->b_data)[0x46 / 2]);
+	vmudata->fat_len = le16_to_cpu(((u16 *) bh->b_data)[0x48 / 2]);
+	vmudata->dir_bnum = le16_to_cpu(((u16 *) bh->b_data)[0x4a / 2]);
+	vmudata->dir_len = le16_to_cpu(((u16 *) bh->b_data)[0x4c / 2]);
+	/* return the true number of user available blocks - VMUs
+ 	* return a neat 200 and ignore 40 blocks of usable space -
+ 	* we get round that in a hardware neutral way */
+	vmudata->numblocks = vmudata->dir_bnum - vmudata->dir_len + 1;
+	sb->s_fs_info = vmudata;
+
+	sb->s_blocksize_bits = ilog2(VMU_BLK_SZ);
+	sb->s_magic = VMUFAT_MAGIC;
+	sb->s_op = &vmufat_super_operations;
+
+	root_i = vmufat_get_inode(sb, vmudata->sb_bnum);
+	if (!root_i) {
+		printk(KERN_ERR "vmufat: get root inode failed\n");
+		ret = -ENOMEM;
+		goto freevmudata_out;
+	}
+	if (IS_ERR(root_i)) {
+		printk(KERN_ERR "vmufat: get root inode failed - error 0x%lX\n",
+			PTR_ERR(root_i));
+		ret = PTR_ERR(root_i);
+		goto freevmudata_out;
+	}
+
+	sb->s_root = d_alloc_root(root_i);
+
+	if (!sb->s_root) {
+		ret = -EIO;
+		goto freeroot_out;
+	}
+	return 0;
+
+freeroot_out:
+	iput(root_i);
+freevmudata_out:
+	kfree(vmudata);
+freebh_out:
+	brelse(bh);
+out:
+	return ret;
+
+}
+
+static const struct address_space_operations vmufat_address_space_operations = {
+	.readpage =	vmufat_readpage,
+	.writepage =	vmufat_writepage,
+	.write_begin =	vmufat_write_begin,
+	.write_end =	generic_write_end,
+};
+
+static const struct super_operations vmufat_super_operations = {
+	.alloc_inode =		vmufat_alloc_inode,
+	.destroy_inode =	vmufat_destroy_inode,
+	.write_inode =		vmufat_write_inode,
+	.delete_inode =		vmufat_delete_inode,
+	.put_super =		vmufat_put_super,
+	.statfs =		vmufat_statfs,
+};
+
+static const struct inode_operations vmufat_inode_operations = {
+	.lookup =	vmufat_inode_lookup,
+	.create =	vmufat_inode_create,
+	.unlink =	vmufat_unlink,
+};
+
+static const struct file_operations vmufat_file_dir_operations = {
+	.owner =	THIS_MODULE,
+	.read =		generic_read_dir,
+	.readdir =	vmufat_readdir,
+	.fsync =	file_fsync,
+};
+
+static const struct file_operations vmufat_file_operations = {
+	.llseek =	generic_file_llseek,
+	.read =		do_sync_read,
+	.write =	do_sync_write,
+	.aio_read =	generic_file_aio_read,
+	.aio_write =	generic_file_aio_write,
+};
+
+static int vmufat_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	return get_sb_bdev(fs_type, flags, dev_name, data, vmufat_fill_super,
+			   mnt);
+}
+
+static struct file_system_type vmufat_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "vmufat",
+	.get_sb		= vmufat_get_sb,
+	.kill_sb	= kill_block_super,
+	.fs_flags	= FS_REQUIRES_DEV,
+};
+
+static int __init init_vmufat_fs(void)
+{
+	int err;
+	err = init_inodecache();
+	if (err)
+		return err;
+	return register_filesystem(&vmufat_fs_type);
+}
+
+static void __exit exit_vmufat_fs(void)
+{
+	destroy_inodecache();
+	unregister_filesystem(&vmufat_fs_type);
+}
+
+module_init(init_vmufat_fs);
+module_exit(exit_vmufat_fs);
+
+MODULE_DESCRIPTION("Filesystem for Sega Dreamcast VMU");
+MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
+MODULE_LICENSE("GPL");