Initial commit

fs/omfs/Kconfig

@@ -0,0 +1,13 @@
+config OMFS_FS
+	tristate "SonicBlue Optimized MPEG File System support"
+	depends on BLOCK
+	select CRC_ITU_T
+	help
+	  This is the proprietary file system used by the Rio Karma music
+	  player and ReplayTV DVR.  Despite the name, this filesystem is not
+	  more efficient than a standard FS for MPEG files, in fact likely
+	  the opposite is true.  Say Y if you have either of these devices
+	  and wish to mount its disk.
+
+	  To compile this file system support as a module, choose M here: the
+	  module will be called omfs.  If unsure, say N.

fs/omfs/Makefile

@@ -0,0 +1,4 @@
+
+obj-$(CONFIG_OMFS_FS) += omfs.o
+
+omfs-y := bitmap.o dir.o file.o inode.o

fs/omfs/bitmap.c

@@ -0,0 +1,193 @@
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <asm/div64.h>
+#include "omfs.h"
+
+unsigned long omfs_count_free(struct super_block *sb)
+{
+	unsigned int i;
+	unsigned long sum = 0;
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	int nbits = sb->s_blocksize * 8;
+
+	for (i = 0; i < sbi->s_imap_size; i++)
+		sum += nbits - bitmap_weight(sbi->s_imap[i], nbits);
+
+	return sum;
+}
+
+/*
+ *  Counts the run of zero bits starting at bit up to max.
+ *  It handles the case where a run might spill over a buffer.
+ *  Called with bitmap lock.
+ */
+static int count_run(unsigned long **addr, int nbits,
+		int addrlen, int bit, int max)
+{
+	int count = 0;
+	int x;
+
+	for (; addrlen > 0; addrlen--, addr++) {
+		x = find_next_bit(*addr, nbits, bit);
+		count += x - bit;
+
+		if (x < nbits || count > max)
+			return min(count, max);
+
+		bit = 0;
+	}
+	return min(count, max);
+}
+
+/*
+ * Sets or clears the run of count bits starting with bit.
+ * Called with bitmap lock.
+ */
+static int set_run(struct super_block *sb, int map,
+		int nbits, int bit, int count, int set)
+{
+	int i;
+	int err;
+	struct buffer_head *bh;
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+
+ 	err = -ENOMEM;
+	bh = sb_bread(sb, clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
+	if (!bh)
+		goto out;
+
+	for (i = 0; i < count; i++, bit++) {
+		if (bit >= nbits) {
+			bit = 0;
+			map++;
+
+			mark_buffer_dirty(bh);
+			brelse(bh);
+			bh = sb_bread(sb,
+				clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
+			if (!bh)
+				goto out;
+		}
+		if (set) {
+			set_bit(bit, sbi->s_imap[map]);
+			set_bit(bit, (unsigned long *)bh->b_data);
+		} else {
+			clear_bit(bit, sbi->s_imap[map]);
+			clear_bit(bit, (unsigned long *)bh->b_data);
+		}
+	}
+	mark_buffer_dirty(bh);
+	brelse(bh);
+	err = 0;
+out:
+	return err;
+}
+
+/*
+ * Tries to allocate exactly one block.  Returns true if successful.
+ */
+int omfs_allocate_block(struct super_block *sb, u64 block)
+{
+	struct buffer_head *bh;
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	int bits_per_entry = 8 * sb->s_blocksize;
+	unsigned int map, bit;
+	int ret = 0;
+	u64 tmp;
+
+	tmp = block;
+	bit = do_div(tmp, bits_per_entry);
+	map = tmp;
+
+	mutex_lock(&sbi->s_bitmap_lock);
+	if (map >= sbi->s_imap_size || test_and_set_bit(bit, sbi->s_imap[map]))
+		goto out;
+
+	if (sbi->s_bitmap_ino > 0) {
+		bh = sb_bread(sb, clus_to_blk(sbi, sbi->s_bitmap_ino) + map);
+		if (!bh)
+			goto out;
+
+		set_bit(bit, (unsigned long *)bh->b_data);
+		mark_buffer_dirty(bh);
+		brelse(bh);
+	}
+	ret = 1;
+out:
+	mutex_unlock(&sbi->s_bitmap_lock);
+	return ret;
+}
+
+
+/*
+ *  Tries to allocate a set of blocks.	The request size depends on the
+ *  type: for inodes, we must allocate sbi->s_mirrors blocks, and for file
+ *  blocks, we try to allocate sbi->s_clustersize, but can always get away
+ *  with just one block.
+ */
+int omfs_allocate_range(struct super_block *sb,
+			int min_request,
+			int max_request,
+			u64 *return_block,
+			int *return_size)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	int bits_per_entry = 8 * sb->s_blocksize;
+	int ret = 0;
+	int i, run, bit;
+
+	mutex_lock(&sbi->s_bitmap_lock);
+	for (i = 0; i < sbi->s_imap_size; i++) {
+		bit = 0;
+		while (bit < bits_per_entry) {
+			bit = find_next_zero_bit(sbi->s_imap[i], bits_per_entry,
+				bit);
+
+			if (bit == bits_per_entry)
+				break;
+
+			run = count_run(&sbi->s_imap[i], bits_per_entry,
+				sbi->s_imap_size-i, bit, max_request);
+
+			if (run >= min_request)
+				goto found;
+			bit += run;
+		}
+	}
+	ret = -ENOSPC;
+	goto out;
+
+found:
+	*return_block = i * bits_per_entry + bit;
+	*return_size = run;
+	ret = set_run(sb, i, bits_per_entry, bit, run, 1);
+
+out:
+	mutex_unlock(&sbi->s_bitmap_lock);
+	return ret;
+}
+
+/*
+ * Clears count bits starting at a given block.
+ */
+int omfs_clear_range(struct super_block *sb, u64 block, int count)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	int bits_per_entry = 8 * sb->s_blocksize;
+	u64 tmp;
+	unsigned int map, bit;
+	int ret;
+
+	tmp = block;
+	bit = do_div(tmp, bits_per_entry);
+	map = tmp;
+
+	if (map >= sbi->s_imap_size)
+		return 0;
+
+	mutex_lock(&sbi->s_bitmap_lock);
+	ret = set_run(sb, map, bits_per_entry, bit, count, 0);
+	mutex_unlock(&sbi->s_bitmap_lock);
+	return ret;
+}

fs/omfs/dir.c

@@ -0,0 +1,475 @@
+/*
+ * OMFS (as used by RIO Karma) directory operations.
+ * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
+ * Released under GPL v2.
+ */
+
+#include <linux/fs.h>
+#include <linux/ctype.h>
+#include <linux/buffer_head.h>
+#include "omfs.h"
+
+static int omfs_hash(const char *name, int namelen, int mod)
+{
+	int i, hash = 0;
+	for (i = 0; i < namelen; i++)
+		hash ^= tolower(name[i]) << (i % 24);
+	return hash % mod;
+}
+
+/*
+ * Finds the bucket for a given name and reads the containing block;
+ * *ofs is set to the offset of the first list entry.
+ */
+static struct buffer_head *omfs_get_bucket(struct inode *dir,
+		const char *name, int namelen, int *ofs)
+{
+	int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
+	int bucket = omfs_hash(name, namelen, nbuckets);
+
+	*ofs = OMFS_DIR_START + bucket * 8;
+	return omfs_bread(dir->i_sb, dir->i_ino);
+}
+
+static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
+				const char *name, int namelen,
+				u64 *prev_block)
+{
+	struct buffer_head *bh;
+	struct omfs_inode *oi;
+	int err = -ENOENT;
+	*prev_block = ~0;
+
+	while (block != ~0) {
+		bh = omfs_bread(dir->i_sb, block);
+		if (!bh) {
+			err = -EIO;
+			goto err;
+		}
+
+		oi = (struct omfs_inode *) bh->b_data;
+		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
+			brelse(bh);
+			goto err;
+		}
+
+		if (strncmp(oi->i_name, name, namelen) == 0)
+			return bh;
+
+		*prev_block = block;
+		block = be64_to_cpu(oi->i_sibling);
+		brelse(bh);
+	}
+err:
+	return ERR_PTR(err);
+}
+
+static struct buffer_head *omfs_find_entry(struct inode *dir,
+					   const char *name, int namelen)
+{
+	struct buffer_head *bh;
+	int ofs;
+	u64 block, dummy;
+
+	bh = omfs_get_bucket(dir, name, namelen, &ofs);
+	if (!bh)
+		return ERR_PTR(-EIO);
+
+	block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
+	brelse(bh);
+
+	return omfs_scan_list(dir, block, name, namelen, &dummy);
+}
+
+int omfs_make_empty(struct inode *inode, struct super_block *sb)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	struct buffer_head *bh;
+	struct omfs_inode *oi;
+
+	bh = omfs_bread(sb, inode->i_ino);
+	if (!bh)
+		return -ENOMEM;
+
+	memset(bh->b_data, 0, sizeof(struct omfs_inode));
+
+	if (S_ISDIR(inode->i_mode)) {
+		memset(&bh->b_data[OMFS_DIR_START], 0xff,
+			sbi->s_sys_blocksize - OMFS_DIR_START);
+	} else
+		omfs_make_empty_table(bh, OMFS_EXTENT_START);
+
+	oi = (struct omfs_inode *) bh->b_data;
+	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
+	oi->i_sibling = ~cpu_to_be64(0ULL);
+
+	mark_buffer_dirty(bh);
+	brelse(bh);
+	return 0;
+}
+
+static int omfs_add_link(struct dentry *dentry, struct inode *inode)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	struct omfs_inode *oi;
+	struct buffer_head *bh;
+	u64 block;
+	__be64 *entry;
+	int ofs;
+
+	/* just prepend to head of queue in proper bucket */
+	bh = omfs_get_bucket(dir, name, namelen, &ofs);
+	if (!bh)
+		goto out;
+
+	entry = (__be64 *) &bh->b_data[ofs];
+	block = be64_to_cpu(*entry);
+	*entry = cpu_to_be64(inode->i_ino);
+	mark_buffer_dirty(bh);
+	brelse(bh);
+
+	/* now set the sibling and parent pointers on the new inode */
+	bh = omfs_bread(dir->i_sb, inode->i_ino);
+	if (!bh)
+		goto out;
+
+	oi = (struct omfs_inode *) bh->b_data;
+	memcpy(oi->i_name, name, namelen);
+	memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
+	oi->i_sibling = cpu_to_be64(block);
+	oi->i_parent = cpu_to_be64(dir->i_ino);
+	mark_buffer_dirty(bh);
+	brelse(bh);
+
+	dir->i_ctime = CURRENT_TIME_SEC;
+
+	/* mark affected inodes dirty to rebuild checksums */
+	mark_inode_dirty(dir);
+	mark_inode_dirty(inode);
+	return 0;
+out:
+	return -ENOMEM;
+}
+
+static int omfs_delete_entry(struct dentry *dentry)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct inode *dirty;
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	struct omfs_inode *oi;
+	struct buffer_head *bh, *bh2;
+	__be64 *entry, next;
+	u64 block, prev;
+	int ofs;
+	int err = -ENOMEM;
+
+	/* delete the proper node in the bucket's linked list */
+	bh = omfs_get_bucket(dir, name, namelen, &ofs);
+	if (!bh)
+		goto out;
+
+	entry = (__be64 *) &bh->b_data[ofs];
+	block = be64_to_cpu(*entry);
+
+	bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
+	if (IS_ERR(bh2)) {
+		err = PTR_ERR(bh2);
+		goto out_free_bh;
+	}
+
+	oi = (struct omfs_inode *) bh2->b_data;
+	next = oi->i_sibling;
+	brelse(bh2);
+
+	if (prev != ~0) {
+		/* found in middle of list, get list ptr */
+		brelse(bh);
+		bh = omfs_bread(dir->i_sb, prev);
+		if (!bh)
+			goto out;
+
+		oi = (struct omfs_inode *) bh->b_data;
+		entry = &oi->i_sibling;
+	}
+
+	*entry = next;
+	mark_buffer_dirty(bh);
+
+	if (prev != ~0) {
+		dirty = omfs_iget(dir->i_sb, prev);
+		if (!IS_ERR(dirty)) {
+			mark_inode_dirty(dirty);
+			iput(dirty);
+		}
+	}
+
+	err = 0;
+out_free_bh:
+	brelse(bh);
+out:
+	return err;
+}
+
+static int omfs_dir_is_empty(struct inode *inode)
+{
+	int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
+	struct buffer_head *bh;
+	u64 *ptr;
+	int i;
+
+	bh = omfs_bread(inode->i_sb, inode->i_ino);
+
+	if (!bh)
+		return 0;
+
+	ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
+
+	for (i = 0; i < nbuckets; i++, ptr++)
+		if (*ptr != ~0)
+			break;
+
+	brelse(bh);
+	return *ptr != ~0;
+}
+
+static int omfs_remove(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	int ret;
+
+
+	if (S_ISDIR(inode->i_mode) &&
+	    !omfs_dir_is_empty(inode))
+		return -ENOTEMPTY;
+
+	ret = omfs_delete_entry(dentry);
+	if (ret)
+		return ret;
+	
+	clear_nlink(inode);
+	mark_inode_dirty(inode);
+	mark_inode_dirty(dir);
+	return 0;
+}
+
+static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	int err;
+	struct inode *inode = omfs_new_inode(dir, mode);
+
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	err = omfs_make_empty(inode, dir->i_sb);
+	if (err)
+		goto out_free_inode;
+
+	err = omfs_add_link(dentry, inode);
+	if (err)
+		goto out_free_inode;
+
+	d_instantiate(dentry, inode);
+	return 0;
+
+out_free_inode:
+	iput(inode);
+	return err;
+}
+
+static int omfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	return omfs_add_node(dir, dentry, mode | S_IFDIR);
+}
+
+static int omfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+		bool excl)
+{
+	return omfs_add_node(dir, dentry, mode | S_IFREG);
+}
+
+static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
+				  unsigned int flags)
+{
+	struct buffer_head *bh;
+	struct inode *inode = NULL;
+
+	if (dentry->d_name.len > OMFS_NAMELEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
+	if (!IS_ERR(bh)) {
+		struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
+		ino_t ino = be64_to_cpu(oi->i_head.h_self);
+		brelse(bh);
+		inode = omfs_iget(dir->i_sb, ino);
+		if (IS_ERR(inode))
+			return ERR_CAST(inode);
+	}
+	d_add(dentry, inode);
+	return NULL;
+}
+
+/* sanity check block's self pointer */
+int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
+	u64 fsblock)
+{
+	int is_bad;
+	u64 ino = be64_to_cpu(header->h_self);
+	is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
+		(ino > sbi->s_num_blocks));
+
+	if (is_bad)
+		printk(KERN_WARNING "omfs: bad hash chain detected\n");
+
+	return is_bad;
+}
+
+static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir,
+		u64 fsblock, int hindex)
+{
+	struct inode *dir = file_inode(filp);
+	struct buffer_head *bh;
+	struct omfs_inode *oi;
+	u64 self;
+	int res = 0;
+	unsigned char d_type;
+
+	/* follow chain in this bucket */
+	while (fsblock != ~0) {
+		bh = omfs_bread(dir->i_sb, fsblock);
+		if (!bh)
+			goto out;
+
+		oi = (struct omfs_inode *) bh->b_data;
+		if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
+			brelse(bh);
+			goto out;
+		}
+
+		self = fsblock;
+		fsblock = be64_to_cpu(oi->i_sibling);
+
+		/* skip visited nodes */
+		if (hindex) {
+			hindex--;
+			brelse(bh);
+			continue;
+		}
+
+		d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
+
+		res = filldir(dirent, oi->i_name, strnlen(oi->i_name,
+			OMFS_NAMELEN), filp->f_pos, self, d_type);
+		brelse(bh);
+		if (res < 0)
+			break;
+		filp->f_pos++;
+	}
+out:
+	return res;
+}
+
+static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+		struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct inode *new_inode = new_dentry->d_inode;
+	struct inode *old_inode = old_dentry->d_inode;
+	int err;
+
+	if (new_inode) {
+		/* overwriting existing file/dir */
+		err = omfs_remove(new_dir, new_dentry);
+		if (err)
+			goto out;
+	}
+
+	/* since omfs locates files by name, we need to unlink _before_
+	 * adding the new link or we won't find the old one */
+	err = omfs_delete_entry(old_dentry);
+	if (err)
+		goto out;
+
+	mark_inode_dirty(old_dir);
+	err = omfs_add_link(new_dentry, old_inode);
+	if (err)
+		goto out;
+
+	old_inode->i_ctime = CURRENT_TIME_SEC;
+	mark_inode_dirty(old_inode);
+out:
+	return err;
+}
+
+static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct inode *dir = file_inode(filp);
+	struct buffer_head *bh;
+	loff_t offset, res;
+	unsigned int hchain, hindex;
+	int nbuckets;
+	u64 fsblock;
+	int ret = -EINVAL;
+
+	if (filp->f_pos >> 32)
+		goto success;
+
+	switch ((unsigned long) filp->f_pos) {
+	case 0:
+		if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0)
+			goto success;
+		filp->f_pos++;
+		/* fall through */
+	case 1:
+		if (filldir(dirent, "..", 2, 1,
+		    parent_ino(filp->f_dentry), DT_DIR) < 0)
+			goto success;
+		filp->f_pos = 1 << 20;
+		/* fall through */
+	}
+
+	nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
+
+	/* high 12 bits store bucket + 1 and low 20 bits store hash index */
+	hchain = (filp->f_pos >> 20) - 1;
+	hindex = filp->f_pos & 0xfffff;
+
+	bh = omfs_bread(dir->i_sb, dir->i_ino);
+	if (!bh)
+		goto out;
+
+	offset = OMFS_DIR_START + hchain * 8;
+
+	for (; hchain < nbuckets; hchain++, offset += 8) {
+		fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset]));
+
+		res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex);
+		hindex = 0;
+		if (res < 0)
+			break;
+
+		filp->f_pos = (hchain+2) << 20;
+	}
+	brelse(bh);
+success:
+	ret = 0;
+out:
+	return ret;
+}
+
+const struct inode_operations omfs_dir_inops = {
+	.lookup = omfs_lookup,
+	.mkdir = omfs_mkdir,
+	.rename = omfs_rename,
+	.create = omfs_create,
+	.unlink = omfs_remove,
+	.rmdir = omfs_remove,
+};
+
+const struct file_operations omfs_dir_operations = {
+	.read = generic_read_dir,
+	.readdir = omfs_readdir,
+	.llseek = generic_file_llseek,
+};

fs/omfs/file.c

@@ -0,0 +1,385 @@
+/*
+ * OMFS (as used by RIO Karma) file operations.
+ * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
+ * Released under GPL v2.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include "omfs.h"
+
+static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
+{
+	return (sbi->s_sys_blocksize - offset -
+		sizeof(struct omfs_extent)) /
+		sizeof(struct omfs_extent_entry) + 1;
+}
+
+void omfs_make_empty_table(struct buffer_head *bh, int offset)
+{
+	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
+
+	oe->e_next = ~cpu_to_be64(0ULL);
+	oe->e_extent_count = cpu_to_be32(1),
+	oe->e_fill = cpu_to_be32(0x22),
+	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
+	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
+}
+
+int omfs_shrink_inode(struct inode *inode)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	struct omfs_extent *oe;
+	struct omfs_extent_entry *entry;
+	struct buffer_head *bh;
+	u64 next, last;
+	u32 extent_count;
+	u32 max_extents;
+	int ret;
+
+	/* traverse extent table, freeing each entry that is greater
+	 * than inode->i_size;
+	 */
+	next = inode->i_ino;
+
+	/* only support truncate -> 0 for now */
+	ret = -EIO;
+	if (inode->i_size != 0)
+		goto out;
+
+	bh = omfs_bread(inode->i_sb, next);
+	if (!bh)
+		goto out;
+
+	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
+
+	for (;;) {
+
+		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
+			goto out_brelse;
+
+		extent_count = be32_to_cpu(oe->e_extent_count);
+
+		if (extent_count > max_extents)
+			goto out_brelse;
+
+		last = next;
+		next = be64_to_cpu(oe->e_next);
+		entry = &oe->e_entry;
+
+		/* ignore last entry as it is the terminator */
+		for (; extent_count > 1; extent_count--) {
+			u64 start, count;
+			start = be64_to_cpu(entry->e_cluster);
+			count = be64_to_cpu(entry->e_blocks);
+
+			omfs_clear_range(inode->i_sb, start, (int) count);
+			entry++;
+		}
+		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
+		mark_buffer_dirty(bh);
+		brelse(bh);
+
+		if (last != inode->i_ino)
+			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
+
+		if (next == ~0)
+			break;
+
+		bh = omfs_bread(inode->i_sb, next);
+		if (!bh)
+			goto out;
+		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
+	}
+	ret = 0;
+out:
+	return ret;
+out_brelse:
+	brelse(bh);
+	return ret;
+}
+
+static void omfs_truncate(struct inode *inode)
+{
+	omfs_shrink_inode(inode);
+	mark_inode_dirty(inode);
+}
+
+/*
+ * Add new blocks to the current extent, or create new entries/continuations
+ * as necessary.
+ */
+static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
+			u64 *ret_block)
+{
+	struct omfs_extent_entry *terminator;
+	struct omfs_extent_entry *entry = &oe->e_entry;
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	u32 extent_count = be32_to_cpu(oe->e_extent_count);
+	u64 new_block = 0;
+	u32 max_count;
+	int new_count;
+	int ret = 0;
+
+	/* reached the end of the extent table with no blocks mapped.
+	 * there are three possibilities for adding: grow last extent,
+	 * add a new extent to the current extent table, and add a
+	 * continuation inode.  in last two cases need an allocator for
+	 * sbi->s_cluster_size
+	 */
+
+	/* TODO: handle holes */
+
+	/* should always have a terminator */
+	if (extent_count < 1)
+		return -EIO;
+
+	/* trivially grow current extent, if next block is not taken */
+	terminator = entry + extent_count - 1;
+	if (extent_count > 1) {
+		entry = terminator-1;
+		new_block = be64_to_cpu(entry->e_cluster) +
+			be64_to_cpu(entry->e_blocks);
+
+		if (omfs_allocate_block(inode->i_sb, new_block)) {
+			be64_add_cpu(&entry->e_blocks, 1);
+			terminator->e_blocks = ~(cpu_to_be64(
+				be64_to_cpu(~terminator->e_blocks) + 1));
+			goto out;
+		}
+	}
+	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
+
+	/* TODO: add a continuation block here */
+	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
+		return -EIO;
+
+	/* try to allocate a new cluster */
+	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
+		&new_block, &new_count);
+	if (ret)
+		goto out_fail;
+
+	/* copy terminator down an entry */
+	entry = terminator;
+	terminator++;
+	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
+
+	entry->e_cluster = cpu_to_be64(new_block);
+	entry->e_blocks = cpu_to_be64((u64) new_count);
+
+	terminator->e_blocks = ~(cpu_to_be64(
+		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
+
+	/* write in new entry */
+	be32_add_cpu(&oe->e_extent_count, 1);
+
+out:
+	*ret_block = new_block;
+out_fail:
+	return ret;
+}
+
+/*
+ * Scans across the directory table for a given file block number.
+ * If block not found, return 0.
+ */
+static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
+			sector_t block, int count, int *left)
+{
+	/* count > 1 because of terminator */
+	sector_t searched = 0;
+	for (; count > 1; count--) {
+		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
+			be64_to_cpu(ent->e_blocks));
+
+		if (block >= searched  &&
+		    block < searched + numblocks) {
+			/*
+			 * found it at cluster + (block - searched)
+			 * numblocks - (block - searched) is remainder
+			 */
+			*left = numblocks - (block - searched);
+			return clus_to_blk(OMFS_SB(inode->i_sb),
+				be64_to_cpu(ent->e_cluster)) +
+				block - searched;
+		}
+		searched += numblocks;
+		ent++;
+	}
+	return 0;
+}
+
+static int omfs_get_block(struct inode *inode, sector_t block,
+			  struct buffer_head *bh_result, int create)
+{
+	struct buffer_head *bh;
+	sector_t next, offset;
+	int ret;
+	u64 uninitialized_var(new_block);
+	u32 max_extents;
+	int extent_count;
+	struct omfs_extent *oe;
+	struct omfs_extent_entry *entry;
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	int max_blocks = bh_result->b_size >> inode->i_blkbits;
+	int remain;
+
+	ret = -EIO;
+	bh = omfs_bread(inode->i_sb, inode->i_ino);
+	if (!bh)
+		goto out;
+
+	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
+	next = inode->i_ino;
+
+	for (;;) {
+
+		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
+			goto out_brelse;
+
+		extent_count = be32_to_cpu(oe->e_extent_count);
+		next = be64_to_cpu(oe->e_next);
+		entry = &oe->e_entry;
+
+		if (extent_count > max_extents)
+			goto out_brelse;
+
+		offset = find_block(inode, entry, block, extent_count, &remain);
+		if (offset > 0) {
+			ret = 0;
+			map_bh(bh_result, inode->i_sb, offset);
+			if (remain > max_blocks)
+				remain = max_blocks;
+			bh_result->b_size = (remain << inode->i_blkbits);
+			goto out_brelse;
+		}
+		if (next == ~0)
+			break;
+
+		brelse(bh);
+		bh = omfs_bread(inode->i_sb, next);
+		if (!bh)
+			goto out;
+		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
+	}
+	if (create) {
+		ret = omfs_grow_extent(inode, oe, &new_block);
+		if (ret == 0) {
+			mark_buffer_dirty(bh);
+			mark_inode_dirty(inode);
+			map_bh(bh_result, inode->i_sb,
+					clus_to_blk(sbi, new_block));
+		}
+	}
+out_brelse:
+	brelse(bh);
+out:
+	return ret;
+}
+
+static int omfs_readpage(struct file *file, struct page *page)
+{
+	return block_read_full_page(page, omfs_get_block);
+}
+
+static int omfs_readpages(struct file *file, struct address_space *mapping,
+		struct list_head *pages, unsigned nr_pages)
+{
+	return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
+}
+
+static int omfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, omfs_get_block, wbc);
+}
+
+static int
+omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+	return mpage_writepages(mapping, wbc, omfs_get_block);
+}
+
+static void omfs_write_failed(struct address_space *mapping, loff_t to)
+{
+	struct inode *inode = mapping->host;
+
+	if (to > inode->i_size) {
+		truncate_pagecache(inode, to, inode->i_size);
+		omfs_truncate(inode);
+	}
+}
+
+static int omfs_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	int ret;
+
+	ret = block_write_begin(mapping, pos, len, flags, pagep,
+				omfs_get_block);
+	if (unlikely(ret))
+		omfs_write_failed(mapping, pos + len);
+
+	return ret;
+}
+
+static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
+{
+	return generic_block_bmap(mapping, block, omfs_get_block);
+}
+
+const struct file_operations omfs_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,
+	.mmap = generic_file_mmap,
+	.fsync = generic_file_fsync,
+	.splice_read = generic_file_splice_read,
+};
+
+static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = inode_change_ok(inode, attr);
+	if (error)
+		return error;
+
+	if ((attr->ia_valid & ATTR_SIZE) &&
+	    attr->ia_size != i_size_read(inode)) {
+		error = inode_newsize_ok(inode, attr->ia_size);
+		if (error)
+			return error;
+		truncate_setsize(inode, attr->ia_size);
+		omfs_truncate(inode);
+	}
+
+	setattr_copy(inode, attr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
+const struct inode_operations omfs_file_inops = {
+	.setattr = omfs_setattr,
+};
+
+const struct address_space_operations omfs_aops = {
+	.readpage = omfs_readpage,
+	.readpages = omfs_readpages,
+	.writepage = omfs_writepage,
+	.writepages = omfs_writepages,
+	.write_begin = omfs_write_begin,
+	.write_end = generic_write_end,
+	.bmap = omfs_bmap,
+};
+

fs/omfs/inode.c

@@ -0,0 +1,588 @@
+/*
+ * Optimized MPEG FS - inode and super operations.
+ * Copyright (C) 2006 Bob Copeland <me@bobcopeland.com>
+ * Released under GPL v2.
+ */
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/parser.h>
+#include <linux/buffer_head.h>
+#include <linux/vmalloc.h>
+#include <linux/writeback.h>
+#include <linux/crc-itu-t.h>
+#include "omfs.h"
+
+MODULE_AUTHOR("Bob Copeland <me@bobcopeland.com>");
+MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
+MODULE_LICENSE("GPL");
+
+struct buffer_head *omfs_bread(struct super_block *sb, sector_t block)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	if (block >= sbi->s_num_blocks)
+		return NULL;
+
+	return sb_bread(sb, clus_to_blk(sbi, block));
+}
+
+struct inode *omfs_new_inode(struct inode *dir, umode_t mode)
+{
+	struct inode *inode;
+	u64 new_block;
+	int err;
+	int len;
+	struct omfs_sb_info *sbi = OMFS_SB(dir->i_sb);
+
+	inode = new_inode(dir->i_sb);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	err = omfs_allocate_range(dir->i_sb, sbi->s_mirrors, sbi->s_mirrors,
+			&new_block, &len);
+	if (err)
+		goto fail;
+
+	inode->i_ino = new_block;
+	inode_init_owner(inode, NULL, mode);
+	inode->i_mapping->a_ops = &omfs_aops;
+
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+	switch (mode & S_IFMT) {
+	case S_IFDIR:
+		inode->i_op = &omfs_dir_inops;
+		inode->i_fop = &omfs_dir_operations;
+		inode->i_size = sbi->s_sys_blocksize;
+		inc_nlink(inode);
+		break;
+	case S_IFREG:
+		inode->i_op = &omfs_file_inops;
+		inode->i_fop = &omfs_file_operations;
+		inode->i_size = 0;
+		break;
+	}
+
+	insert_inode_hash(inode);
+	mark_inode_dirty(inode);
+	return inode;
+fail:
+	make_bad_inode(inode);
+	iput(inode);
+	return ERR_PTR(err);
+}
+
+/*
+ * Update the header checksums for a dirty inode based on its contents.
+ * Caller is expected to hold the buffer head underlying oi and mark it
+ * dirty.
+ */
+static void omfs_update_checksums(struct omfs_inode *oi)
+{
+	int xor, i, ofs = 0, count;
+	u16 crc = 0;
+	unsigned char *ptr = (unsigned char *) oi;
+
+	count = be32_to_cpu(oi->i_head.h_body_size);
+	ofs = sizeof(struct omfs_header);
+
+	crc = crc_itu_t(crc, ptr + ofs, count);
+	oi->i_head.h_crc = cpu_to_be16(crc);
+
+	xor = ptr[0];
+	for (i = 1; i < OMFS_XOR_COUNT; i++)
+		xor ^= ptr[i];
+
+	oi->i_head.h_check_xor = xor;
+}
+
+static int __omfs_write_inode(struct inode *inode, int wait)
+{
+	struct omfs_inode *oi;
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	struct buffer_head *bh, *bh2;
+	u64 ctime;
+	int i;
+	int ret = -EIO;
+	int sync_failed = 0;
+
+	/* get current inode since we may have written sibling ptrs etc. */
+	bh = omfs_bread(inode->i_sb, inode->i_ino);
+	if (!bh)
+		goto out;
+
+	oi = (struct omfs_inode *) bh->b_data;
+
+	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
+	if (S_ISDIR(inode->i_mode))
+		oi->i_type = OMFS_DIR;
+	else if (S_ISREG(inode->i_mode))
+		oi->i_type = OMFS_FILE;
+	else {
+		printk(KERN_WARNING "omfs: unknown file type: %d\n",
+			inode->i_mode);
+		goto out_brelse;
+	}
+
+	oi->i_head.h_body_size = cpu_to_be32(sbi->s_sys_blocksize -
+		sizeof(struct omfs_header));
+	oi->i_head.h_version = 1;
+	oi->i_head.h_type = OMFS_INODE_NORMAL;
+	oi->i_head.h_magic = OMFS_IMAGIC;
+	oi->i_size = cpu_to_be64(inode->i_size);
+
+	ctime = inode->i_ctime.tv_sec * 1000LL +
+		((inode->i_ctime.tv_nsec + 999)/1000);
+	oi->i_ctime = cpu_to_be64(ctime);
+
+	omfs_update_checksums(oi);
+
+	mark_buffer_dirty(bh);
+	if (wait) {
+		sync_dirty_buffer(bh);
+		if (buffer_req(bh) && !buffer_uptodate(bh))
+			sync_failed = 1;
+	}
+
+	/* if mirroring writes, copy to next fsblock */
+	for (i = 1; i < sbi->s_mirrors; i++) {
+		bh2 = omfs_bread(inode->i_sb, inode->i_ino + i);
+		if (!bh2)
+			goto out_brelse;
+
+		memcpy(bh2->b_data, bh->b_data, bh->b_size);
+		mark_buffer_dirty(bh2);
+		if (wait) {
+			sync_dirty_buffer(bh2);
+			if (buffer_req(bh2) && !buffer_uptodate(bh2))
+				sync_failed = 1;
+		}
+		brelse(bh2);
+	}
+	ret = (sync_failed) ? -EIO : 0;
+out_brelse:
+	brelse(bh);
+out:
+	return ret;
+}
+
+static int omfs_write_inode(struct inode *inode, struct writeback_control *wbc)
+{
+	return __omfs_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
+}
+
+int omfs_sync_inode(struct inode *inode)
+{
+	return __omfs_write_inode(inode, 1);
+}
+
+/*
+ * called when an entry is deleted, need to clear the bits in the
+ * bitmaps.
+ */
+static void omfs_evict_inode(struct inode *inode)
+{
+	truncate_inode_pages(&inode->i_data, 0);
+	clear_inode(inode);
+
+	if (inode->i_nlink)
+		return;
+
+	if (S_ISREG(inode->i_mode)) {
+		inode->i_size = 0;
+		omfs_shrink_inode(inode);
+	}
+
+	omfs_clear_range(inode->i_sb, inode->i_ino, 2);
+}
+
+struct inode *omfs_iget(struct super_block *sb, ino_t ino)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	struct omfs_inode *oi;
+	struct buffer_head *bh;
+	u64 ctime;
+	unsigned long nsecs;
+	struct inode *inode;
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	bh = omfs_bread(inode->i_sb, ino);
+	if (!bh)
+		goto iget_failed;
+
+	oi = (struct omfs_inode *)bh->b_data;
+
+	/* check self */
+	if (ino != be64_to_cpu(oi->i_head.h_self))
+		goto fail_bh;
+
+	inode->i_uid = sbi->s_uid;
+	inode->i_gid = sbi->s_gid;
+
+	ctime = be64_to_cpu(oi->i_ctime);
+	nsecs = do_div(ctime, 1000) * 1000L;
+
+	inode->i_atime.tv_sec = ctime;
+	inode->i_mtime.tv_sec = ctime;
+	inode->i_ctime.tv_sec = ctime;
+	inode->i_atime.tv_nsec = nsecs;
+	inode->i_mtime.tv_nsec = nsecs;
+	inode->i_ctime.tv_nsec = nsecs;
+
+	inode->i_mapping->a_ops = &omfs_aops;
+
+	switch (oi->i_type) {
+	case OMFS_DIR:
+		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~sbi->s_dmask);
+		inode->i_op = &omfs_dir_inops;
+		inode->i_fop = &omfs_dir_operations;
+		inode->i_size = sbi->s_sys_blocksize;
+		inc_nlink(inode);
+		break;
+	case OMFS_FILE:
+		inode->i_mode = S_IFREG | (S_IRWXUGO & ~sbi->s_fmask);
+		inode->i_fop = &omfs_file_operations;
+		inode->i_size = be64_to_cpu(oi->i_size);
+		break;
+	}
+	brelse(bh);
+	unlock_new_inode(inode);
+	return inode;
+fail_bh:
+	brelse(bh);
+iget_failed:
+	iget_failed(inode);
+	return ERR_PTR(-EIO);
+}
+
+static void omfs_put_super(struct super_block *sb)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	kfree(sbi->s_imap);
+	kfree(sbi);
+	sb->s_fs_info = NULL;
+}
+
+static int omfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *s = dentry->d_sb;
+	struct omfs_sb_info *sbi = OMFS_SB(s);
+	u64 id = huge_encode_dev(s->s_bdev->bd_dev);
+
+	buf->f_type = OMFS_MAGIC;
+	buf->f_bsize = sbi->s_blocksize;
+	buf->f_blocks = sbi->s_num_blocks;
+	buf->f_files = sbi->s_num_blocks;
+	buf->f_namelen = OMFS_NAMELEN;
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
+
+	buf->f_bfree = buf->f_bavail = buf->f_ffree =
+		omfs_count_free(s);
+
+	return 0;
+}
+
+static const struct super_operations omfs_sops = {
+	.write_inode	= omfs_write_inode,
+	.evict_inode	= omfs_evict_inode,
+	.put_super	= omfs_put_super,
+	.statfs		= omfs_statfs,
+	.show_options	= generic_show_options,
+};
+
+/*
+ * For Rio Karma, there is an on-disk free bitmap whose location is
+ * stored in the root block.  For ReplayTV, there is no such free bitmap
+ * so we have to walk the tree.  Both inodes and file data are allocated
+ * from the same map.  This array can be big (300k) so we allocate
+ * in units of the blocksize.
+ */
+static int omfs_get_imap(struct super_block *sb)
+{
+	int bitmap_size;
+	int array_size;
+	int count;
+	struct omfs_sb_info *sbi = OMFS_SB(sb);
+	struct buffer_head *bh;
+	unsigned long **ptr;
+	sector_t block;
+
+	bitmap_size = DIV_ROUND_UP(sbi->s_num_blocks, 8);
+	array_size = DIV_ROUND_UP(bitmap_size, sb->s_blocksize);
+
+	if (sbi->s_bitmap_ino == ~0ULL)
+		goto out;
+
+	sbi->s_imap_size = array_size;
+	sbi->s_imap = kzalloc(array_size * sizeof(unsigned long *), GFP_KERNEL);
+	if (!sbi->s_imap)
+		goto nomem;
+
+	block = clus_to_blk(sbi, sbi->s_bitmap_ino);
+	if (block >= sbi->s_num_blocks)
+		goto nomem;
+
+	ptr = sbi->s_imap;
+	for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
+		bh = sb_bread(sb, block++);
+		if (!bh)
+			goto nomem_free;
+		*ptr = kmalloc(sb->s_blocksize, GFP_KERNEL);
+		if (!*ptr) {
+			brelse(bh);
+			goto nomem_free;
+		}
+		memcpy(*ptr, bh->b_data, sb->s_blocksize);
+		if (count < sb->s_blocksize)
+			memset((void *)*ptr + count, 0xff,
+				sb->s_blocksize - count);
+		brelse(bh);
+		ptr++;
+	}
+out:
+	return 0;
+
+nomem_free:
+	for (count = 0; count < array_size; count++)
+		kfree(sbi->s_imap[count]);
+
+	kfree(sbi->s_imap);
+nomem:
+	sbi->s_imap = NULL;
+	sbi->s_imap_size = 0;
+	return -ENOMEM;
+}
+
+enum {
+	Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask
+};
+
+static const match_table_t tokens = {
+	{Opt_uid, "uid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_umask, "umask=%o"},
+	{Opt_dmask, "dmask=%o"},
+	{Opt_fmask, "fmask=%o"},
+};
+
+static int parse_options(char *options, struct omfs_sb_info *sbi)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+
+	if (!options)
+		return 1;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_uid:
+			if (match_int(&args[0], &option))
+				return 0;
+			sbi->s_uid = make_kuid(current_user_ns(), option);
+			if (!uid_valid(sbi->s_uid))
+				return 0;
+			break;
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			sbi->s_gid = make_kgid(current_user_ns(), option);
+			if (!gid_valid(sbi->s_gid))
+				return 0;
+			break;
+		case Opt_umask:
+			if (match_octal(&args[0], &option))
+				return 0;
+			sbi->s_fmask = sbi->s_dmask = option;
+			break;
+		case Opt_dmask:
+			if (match_octal(&args[0], &option))
+				return 0;
+			sbi->s_dmask = option;
+			break;
+		case Opt_fmask:
+			if (match_octal(&args[0], &option))
+				return 0;
+			sbi->s_fmask = option;
+			break;
+		default:
+			return 0;
+		}
+	}
+	return 1;
+}
+
+static int omfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct buffer_head *bh, *bh2;
+	struct omfs_super_block *omfs_sb;
+	struct omfs_root_block *omfs_rb;
+	struct omfs_sb_info *sbi;
+	struct inode *root;
+	int ret = -EINVAL;
+
+	save_mount_options(sb, (char *) data);
+
+	sbi = kzalloc(sizeof(struct omfs_sb_info), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+
+	sb->s_fs_info = sbi;
+
+	sbi->s_uid = current_uid();
+	sbi->s_gid = current_gid();
+	sbi->s_dmask = sbi->s_fmask = current_umask();
+
+	if (!parse_options((char *) data, sbi))
+		goto end;
+
+	sb->s_maxbytes = 0xffffffff;
+
+	sb_set_blocksize(sb, 0x200);
+
+	bh = sb_bread(sb, 0);
+	if (!bh)
+		goto end;
+
+	omfs_sb = (struct omfs_super_block *)bh->b_data;
+
+	if (omfs_sb->s_magic != cpu_to_be32(OMFS_MAGIC)) {
+		if (!silent)
+			printk(KERN_ERR "omfs: Invalid superblock (%x)\n",
+				   omfs_sb->s_magic);
+		goto out_brelse_bh;
+	}
+	sb->s_magic = OMFS_MAGIC;
+
+	sbi->s_num_blocks = be64_to_cpu(omfs_sb->s_num_blocks);
+	sbi->s_blocksize = be32_to_cpu(omfs_sb->s_blocksize);
+	sbi->s_mirrors = be32_to_cpu(omfs_sb->s_mirrors);
+	sbi->s_root_ino = be64_to_cpu(omfs_sb->s_root_block);
+	sbi->s_sys_blocksize = be32_to_cpu(omfs_sb->s_sys_blocksize);
+	mutex_init(&sbi->s_bitmap_lock);
+
+	if (sbi->s_sys_blocksize > PAGE_SIZE) {
+		printk(KERN_ERR "omfs: sysblock size (%d) is out of range\n",
+			sbi->s_sys_blocksize);
+		goto out_brelse_bh;
+	}
+
+	if (sbi->s_blocksize < sbi->s_sys_blocksize ||
+	    sbi->s_blocksize > OMFS_MAX_BLOCK_SIZE) {
+		printk(KERN_ERR "omfs: block size (%d) is out of range\n",
+			sbi->s_blocksize);
+		goto out_brelse_bh;
+	}
+
+	/*
+	 * Use sys_blocksize as the fs block since it is smaller than a
+	 * page while the fs blocksize can be larger.
+	 */
+	sb_set_blocksize(sb, sbi->s_sys_blocksize);
+
+	/*
+	 * ...and the difference goes into a shift.  sys_blocksize is always
+	 * a power of two factor of blocksize.
+	 */
+	sbi->s_block_shift = get_bitmask_order(sbi->s_blocksize) -
+		get_bitmask_order(sbi->s_sys_blocksize);
+
+	bh2 = omfs_bread(sb, be64_to_cpu(omfs_sb->s_root_block));
+	if (!bh2)
+		goto out_brelse_bh;
+
+	omfs_rb = (struct omfs_root_block *)bh2->b_data;
+
+	sbi->s_bitmap_ino = be64_to_cpu(omfs_rb->r_bitmap);
+	sbi->s_clustersize = be32_to_cpu(omfs_rb->r_clustersize);
+
+	if (sbi->s_num_blocks != be64_to_cpu(omfs_rb->r_num_blocks)) {
+		printk(KERN_ERR "omfs: block count discrepancy between "
+			"super and root blocks (%llx, %llx)\n",
+			(unsigned long long)sbi->s_num_blocks,
+			(unsigned long long)be64_to_cpu(omfs_rb->r_num_blocks));
+		goto out_brelse_bh2;
+	}
+
+	if (sbi->s_bitmap_ino != ~0ULL &&
+	    sbi->s_bitmap_ino > sbi->s_num_blocks) {
+		printk(KERN_ERR "omfs: free space bitmap location is corrupt "
+			"(%llx, total blocks %llx)\n",
+			(unsigned long long) sbi->s_bitmap_ino,
+			(unsigned long long) sbi->s_num_blocks);
+		goto out_brelse_bh2;
+	}
+	if (sbi->s_clustersize < 1 ||
+	    sbi->s_clustersize > OMFS_MAX_CLUSTER_SIZE) {
+		printk(KERN_ERR "omfs: cluster size out of range (%d)",
+			sbi->s_clustersize);
+		goto out_brelse_bh2;
+	}
+
+	ret = omfs_get_imap(sb);
+	if (ret)
+		goto out_brelse_bh2;
+
+	sb->s_op = &omfs_sops;
+
+	root = omfs_iget(sb, be64_to_cpu(omfs_rb->r_root_dir));
+	if (IS_ERR(root)) {
+		ret = PTR_ERR(root);
+		goto out_brelse_bh2;
+	}
+
+	sb->s_root = d_make_root(root);
+	if (!sb->s_root)
+		goto out_brelse_bh2;
+	printk(KERN_DEBUG "omfs: Mounted volume %s\n", omfs_rb->r_name);
+
+	ret = 0;
+out_brelse_bh2:
+	brelse(bh2);
+out_brelse_bh:
+	brelse(bh);
+end:
+	if (ret)
+		kfree(sbi);
+	return ret;
+}
+
+static struct dentry *omfs_mount(struct file_system_type *fs_type,
+			int flags, const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, omfs_fill_super);
+}
+
+static struct file_system_type omfs_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "omfs",
+	.mount = omfs_mount,
+	.kill_sb = kill_block_super,
+	.fs_flags = FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("omfs");
+
+static int __init init_omfs_fs(void)
+{
+	return register_filesystem(&omfs_fs_type);
+}
+
+static void __exit exit_omfs_fs(void)
+{
+	unregister_filesystem(&omfs_fs_type);
+}
+
+module_init(init_omfs_fs);
+module_exit(exit_omfs_fs);

fs/omfs/omfs.h

@@ -0,0 +1,68 @@
+#ifndef _OMFS_H
+#define _OMFS_H
+
+#include <linux/module.h>
+#include <linux/fs.h>
+
+#include "omfs_fs.h"
+
+/* In-memory structures */
+struct omfs_sb_info {
+	u64 s_num_blocks;
+	u64 s_bitmap_ino;
+	u64 s_root_ino;
+	u32 s_blocksize;
+	u32 s_mirrors;
+	u32 s_sys_blocksize;
+	u32 s_clustersize;
+	int s_block_shift;
+	unsigned long **s_imap;
+	int s_imap_size;
+	struct mutex s_bitmap_lock;
+	kuid_t s_uid;
+	kgid_t s_gid;
+	int s_dmask;
+	int s_fmask;
+};
+
+/* convert a cluster number to a scaled block number */
+static inline sector_t clus_to_blk(struct omfs_sb_info *sbi, sector_t block)
+{
+	return block << sbi->s_block_shift;
+}
+
+static inline struct omfs_sb_info *OMFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+/* bitmap.c */
+extern unsigned long omfs_count_free(struct super_block *sb);
+extern int omfs_allocate_block(struct super_block *sb, u64 block);
+extern int omfs_allocate_range(struct super_block *sb, int min_request,
+			int max_request, u64 *return_block, int *return_size);
+extern int omfs_clear_range(struct super_block *sb, u64 block, int count);
+
+/* dir.c */
+extern const struct file_operations omfs_dir_operations;
+extern const struct inode_operations omfs_dir_inops;
+extern int omfs_make_empty(struct inode *inode, struct super_block *sb);
+extern int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
+			u64 fsblock);
+
+/* file.c */
+extern const struct file_operations omfs_file_operations;
+extern const struct inode_operations omfs_file_inops;
+extern const struct address_space_operations omfs_aops;
+extern void omfs_make_empty_table(struct buffer_head *bh, int offset);
+extern int omfs_shrink_inode(struct inode *inode);
+
+/* inode.c */
+extern struct buffer_head *omfs_bread(struct super_block *sb, sector_t block);
+extern struct inode *omfs_iget(struct super_block *sb, ino_t inode);
+extern struct inode *omfs_new_inode(struct inode *dir, umode_t mode);
+extern int omfs_reserve_block(struct super_block *sb, sector_t block);
+extern int omfs_find_empty_block(struct super_block *sb, int mode, ino_t *ino);
+extern int omfs_sync_inode(struct inode *inode);
+
+#endif

fs/omfs/omfs_fs.h

@@ -0,0 +1,81 @@
+#ifndef _OMFS_FS_H
+#define _OMFS_FS_H
+
+/* OMFS On-disk structures */
+
+#define OMFS_MAGIC 0xC2993D87
+#define OMFS_IMAGIC 0xD2
+
+#define OMFS_DIR 'D'
+#define OMFS_FILE 'F'
+#define OMFS_INODE_NORMAL 'e'
+#define OMFS_INODE_CONTINUATION 'c'
+#define OMFS_INODE_SYSTEM 's'
+#define OMFS_NAMELEN 256
+#define OMFS_DIR_START 0x1b8
+#define OMFS_EXTENT_START 0x1d0
+#define OMFS_EXTENT_CONT 0x40
+#define OMFS_XOR_COUNT 19
+#define OMFS_MAX_BLOCK_SIZE 8192
+#define OMFS_MAX_CLUSTER_SIZE 8
+
+struct omfs_super_block {
+	char s_fill1[256];
+	__be64 s_root_block;		/* block number of omfs_root_block */
+	__be64 s_num_blocks;		/* total number of FS blocks */
+	__be32 s_magic;			/* OMFS_MAGIC */
+	__be32 s_blocksize;		/* size of a block */
+	__be32 s_mirrors;		/* # of mirrors of system blocks */
+	__be32 s_sys_blocksize;		/* size of non-data blocks */
+};
+
+struct omfs_header {
+	__be64 h_self;			/* FS block where this is located */
+	__be32 h_body_size;		/* size of useful data after header */
+	__be16 h_crc;			/* crc-ccitt of body_size bytes */
+	char h_fill1[2];
+	u8 h_version;			/* version, always 1 */
+	char h_type;			/* OMFS_INODE_X */
+	u8 h_magic;			/* OMFS_IMAGIC */
+	u8 h_check_xor;			/* XOR of header bytes before this */
+	__be32 h_fill2;
+};
+
+struct omfs_root_block {
+	struct omfs_header r_head;	/* header */
+	__be64 r_fill1;
+	__be64 r_num_blocks;		/* total number of FS blocks */
+	__be64 r_root_dir;		/* block # of root directory */
+	__be64 r_bitmap;		/* block # of free space bitmap */
+	__be32 r_blocksize;		/* size of a block */
+	__be32 r_clustersize;		/* size allocated for data blocks */
+	__be64 r_mirrors;		/* # of mirrors of system blocks */
+	char r_name[OMFS_NAMELEN];	/* partition label */
+};
+
+struct omfs_inode {
+	struct omfs_header i_head;	/* header */
+	__be64 i_parent;		/* parent containing this inode */
+	__be64 i_sibling;		/* next inode in hash bucket */
+	__be64 i_ctime;			/* ctime, in milliseconds */
+	char i_fill1[35];
+	char i_type;			/* OMFS_[DIR,FILE] */
+	__be32 i_fill2;
+	char i_fill3[64];
+	char i_name[OMFS_NAMELEN];	/* filename */
+	__be64 i_size;			/* size of file, in bytes */
+};
+
+struct omfs_extent_entry {
+	__be64 e_cluster;		/* start location of a set of blocks */
+	__be64 e_blocks;		/* number of blocks after e_cluster */
+};
+
+struct omfs_extent {
+	__be64 e_next;			/* next extent table location */
+	__be32 e_extent_count;		/* total # extents in this table */
+	__be32 e_fill;
+	struct omfs_extent_entry e_entry;	/* start of extent entries */
+};
+
+#endif