fs/bfs/inode.c - pub/scm/linux/kernel/git/ebiederm/linux-namespace-control-devel - Git at Google

 /*
  *	fs/bfs/inode.c
  *	BFS superblock and inode operations.
  *	Copyright (C) 1999-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
  *	From fs/minix, Copyright (C) 1991, 1992 Linus Torvalds.
  *
  *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org>, 2005.
  */

 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/buffer_head.h>
 #include <linux/vfs.h>
 #include <linux/writeback.h>
 #include <asm/uaccess.h>
 #include "bfs.h"

 MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");
 MODULE_DESCRIPTION("SCO UnixWare BFS filesystem for Linux");
 MODULE_LICENSE("GPL");

 #undef DEBUG

 #ifdef DEBUG
 #define dprintf(x...)	printf(x)
 #else
 #define dprintf(x...)
 #endif

 void dump_imap(const char *prefix, struct super_block *s);

 struct inode *bfs_iget(struct super_block *sb, unsigned long ino)
 {
 	struct bfs_inode *di;
 	struct inode *inode;
 	struct buffer_head *bh;
 	int block, off;

 	inode = iget_locked(sb, ino);
 	if (IS_ERR(inode))
 		return ERR_PTR(-ENOMEM);
 	if (!(inode->i_state & I_NEW))
 		return inode;

 	if ((ino < BFS_ROOT_INO) || (ino > BFS_SB(inode->i_sb)->si_lasti)) {
 		printf("Bad inode number %s:%08lx\n", inode->i_sb->s_id, ino);
 		goto error;
 	}

 	block = (ino - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;
 	bh = sb_bread(inode->i_sb, block);
 	if (!bh) {
 		printf("Unable to read inode %s:%08lx\n", inode->i_sb->s_id,
 									ino);
 		goto error;
 	}

 	off = (ino - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;
 	di = (struct bfs_inode *)bh->b_data + off;

 	inode->i_mode = 0x0000FFFF & le32_to_cpu(di->i_mode);
 	if (le32_to_cpu(di->i_vtype) == BFS_VDIR) {
 		inode->i_mode |= S_IFDIR;
 		inode->i_op = &bfs_dir_inops;
 		inode->i_fop = &bfs_dir_operations;
 	} else if (le32_to_cpu(di->i_vtype) == BFS_VREG) {
 		inode->i_mode |= S_IFREG;
 		inode->i_op = &bfs_file_inops;
 		inode->i_fop = &bfs_file_operations;
 		inode->i_mapping->a_ops = &bfs_aops;
 	}

 	BFS_I(inode)->i_sblock =  le32_to_cpu(di->i_sblock);
 	BFS_I(inode)->i_eblock =  le32_to_cpu(di->i_eblock);
 	BFS_I(inode)->i_dsk_ino = le16_to_cpu(di->i_ino);
 	inode->i_uid =  le32_to_cpu(di->i_uid);
 	inode->i_gid =  le32_to_cpu(di->i_gid);
 	inode->i_nlink =  le32_to_cpu(di->i_nlink);
 	inode->i_size = BFS_FILESIZE(di);
 	inode->i_blocks = BFS_FILEBLOCKS(di);
 	inode->i_atime.tv_sec =  le32_to_cpu(di->i_atime);
 	inode->i_mtime.tv_sec =  le32_to_cpu(di->i_mtime);
 	inode->i_ctime.tv_sec =  le32_to_cpu(di->i_ctime);
 	inode->i_atime.tv_nsec = 0;
 	inode->i_mtime.tv_nsec = 0;
 	inode->i_ctime.tv_nsec = 0;

 	brelse(bh);
 	unlock_new_inode(inode);
 	return inode;

 error:
 	iget_failed(inode);
 	return ERR_PTR(-EIO);
 }

 static struct bfs_inode *find_inode(struct super_block *sb, u16 ino, struct buffer_head **p)
 {
 	if ((ino < BFS_ROOT_INO) || (ino > BFS_SB(sb)->si_lasti)) {
 		printf("Bad inode number %s:%08x\n", sb->s_id, ino);
 		return ERR_PTR(-EIO);
 	}

 	ino -= BFS_ROOT_INO;

 	*p = sb_bread(sb, 1 + ino / BFS_INODES_PER_BLOCK);
 	if (!*p) {
 		printf("Unable to read inode %s:%08x\n", sb->s_id, ino);
 		return ERR_PTR(-EIO);
 	}

 	return (struct bfs_inode *)(*p)->b_data +  ino % BFS_INODES_PER_BLOCK;
 }

 static int bfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
 	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
 	unsigned int ino = (u16)inode->i_ino;
         unsigned long i_sblock;
 	struct bfs_inode *di;
 	struct buffer_head *bh;
 	int err = 0;

         dprintf("ino=%08x\n", ino);

 	di = find_inode(inode->i_sb, ino, &bh);
 	if (IS_ERR(di))
 		return PTR_ERR(di);

 	mutex_lock(&info->bfs_lock);

 	if (ino == BFS_ROOT_INO)
 		di->i_vtype = cpu_to_le32(BFS_VDIR);
 	else
 		di->i_vtype = cpu_to_le32(BFS_VREG);

 	di->i_ino = cpu_to_le16(ino);
 	di->i_mode = cpu_to_le32(inode->i_mode);
 	di->i_uid = cpu_to_le32(inode->i_uid);
 	di->i_gid = cpu_to_le32(inode->i_gid);
 	di->i_nlink = cpu_to_le32(inode->i_nlink);
 	di->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
 	di->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
 	di->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
         i_sblock = BFS_I(inode)->i_sblock;
 	di->i_sblock = cpu_to_le32(i_sblock);
 	di->i_eblock = cpu_to_le32(BFS_I(inode)->i_eblock);
 	di->i_eoffset = cpu_to_le32(i_sblock * BFS_BSIZE + inode->i_size - 1);

 	mark_buffer_dirty(bh);
 	if (wbc->sync_mode == WB_SYNC_ALL) {
 		sync_dirty_buffer(bh);
 		if (buffer_req(bh) && !buffer_uptodate(bh))
 			err = -EIO;
 	}
 	brelse(bh);
 	mutex_unlock(&info->bfs_lock);
 	return err;
 }

 static void bfs_evict_inode(struct inode *inode)
 {
 	unsigned long ino = inode->i_ino;
 	struct bfs_inode *di;
 	struct buffer_head *bh;
 	struct super_block *s = inode->i_sb;
 	struct bfs_sb_info *info = BFS_SB(s);
 	struct bfs_inode_info *bi = BFS_I(inode);

 	dprintf("ino=%08lx\n", ino);

 	truncate_inode_pages(&inode->i_data, 0);
 	invalidate_inode_buffers(inode);
 	end_writeback(inode);

 	if (inode->i_nlink)
 		return;

 	di = find_inode(s, inode->i_ino, &bh);
 	if (IS_ERR(di))
 		return;

 	mutex_lock(&info->bfs_lock);
 	/* clear on-disk inode */
 	memset(di, 0, sizeof(struct bfs_inode));
 	mark_buffer_dirty(bh);
 	brelse(bh);

         if (bi->i_dsk_ino) {
 		if (bi->i_sblock)
 			info->si_freeb += bi->i_eblock + 1 - bi->i_sblock;
 		info->si_freei++;
 		clear_bit(ino, info->si_imap);
 		dump_imap("delete_inode", s);
         }

 	/*
 	 * If this was the last file, make the previous block
 	 * "last block of the last file" even if there is no
 	 * real file there, saves us 1 gap.
 	 */
 	if (info->si_lf_eblk == bi->i_eblock)
 		info->si_lf_eblk = bi->i_sblock - 1;
 	mutex_unlock(&info->bfs_lock);
 }

 static void bfs_put_super(struct super_block *s)
 {
 	struct bfs_sb_info *info = BFS_SB(s);

 	if (!info)
 		return;

 	mutex_destroy(&info->bfs_lock);
 	kfree(info->si_imap);
 	kfree(info);
 	s->s_fs_info = NULL;
 }

 static int bfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *s = dentry->d_sb;
 	struct bfs_sb_info *info = BFS_SB(s);
 	u64 id = huge_encode_dev(s->s_bdev->bd_dev);
 	buf->f_type = BFS_MAGIC;
 	buf->f_bsize = s->s_blocksize;
 	buf->f_blocks = info->si_blocks;
 	buf->f_bfree = buf->f_bavail = info->si_freeb;
 	buf->f_files = info->si_lasti + 1 - BFS_ROOT_INO;
 	buf->f_ffree = info->si_freei;
 	buf->f_fsid.val[0] = (u32)id;
 	buf->f_fsid.val[1] = (u32)(id >> 32);
 	buf->f_namelen = BFS_NAMELEN;
 	return 0;
 }

 static struct kmem_cache *bfs_inode_cachep;

 static struct inode *bfs_alloc_inode(struct super_block *sb)
 {
 	struct bfs_inode_info *bi;
 	bi = kmem_cache_alloc(bfs_inode_cachep, GFP_KERNEL);
 	if (!bi)
 		return NULL;
 	return &bi->vfs_inode;
 }

 static void bfs_i_callback(struct rcu_head *head)
 {
 	struct inode *inode = container_of(head, struct inode, i_rcu);
 	INIT_LIST_HEAD(&inode->i_dentry);
 	kmem_cache_free(bfs_inode_cachep, BFS_I(inode));
 }

 static void bfs_destroy_inode(struct inode *inode)
 {
 	call_rcu(&inode->i_rcu, bfs_i_callback);
 }

 static void init_once(void *foo)
 {
 	struct bfs_inode_info *bi = foo;

 	inode_init_once(&bi->vfs_inode);
 }

 static int init_inodecache(void)
 {
 	bfs_inode_cachep = kmem_cache_create("bfs_inode_cache",
 					     sizeof(struct bfs_inode_info),
 					     0, (SLAB_RECLAIM_ACCOUNT|
 						SLAB_MEM_SPREAD),
 					     init_once);
 	if (bfs_inode_cachep == NULL)
 		return -ENOMEM;
 	return 0;
 }

 static void destroy_inodecache(void)
 {
 	kmem_cache_destroy(bfs_inode_cachep);
 }

 static const struct super_operations bfs_sops = {
 	.alloc_inode	= bfs_alloc_inode,
 	.destroy_inode	= bfs_destroy_inode,
 	.write_inode	= bfs_write_inode,
 	.evict_inode	= bfs_evict_inode,
 	.put_super	= bfs_put_super,
 	.statfs		= bfs_statfs,
 };

 void dump_imap(const char *prefix, struct super_block *s)
 {
 #ifdef DEBUG
 	int i;
 	char *tmpbuf = (char *)get_zeroed_page(GFP_KERNEL);

 	if (!tmpbuf)
 		return;
 	for (i = BFS_SB(s)->si_lasti; i >= 0; i--) {
 		if (i > PAGE_SIZE - 100) break;
 		if (test_bit(i, BFS_SB(s)->si_imap))
 			strcat(tmpbuf, "1");
 		else
 			strcat(tmpbuf, "0");
 	}
 	printf("BFS-fs: %s: lasti=%08lx <%s>\n",
 				prefix, BFS_SB(s)->si_lasti, tmpbuf);
 	free_page((unsigned long)tmpbuf);
 #endif
 }

 static int bfs_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct buffer_head *bh, *sbh;
 	struct bfs_super_block *bfs_sb;
 	struct inode *inode;
 	unsigned i, imap_len;
 	struct bfs_sb_info *info;
 	int ret = -EINVAL;
 	unsigned long i_sblock, i_eblock, i_eoff, s_size;

 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;
 	mutex_init(&info->bfs_lock);
 	s->s_fs_info = info;

 	sb_set_blocksize(s, BFS_BSIZE);

 	sbh = sb_bread(s, 0);
 	if (!sbh)
 		goto out;
 	bfs_sb = (struct bfs_super_block *)sbh->b_data;
 	if (le32_to_cpu(bfs_sb->s_magic) != BFS_MAGIC) {
 		if (!silent)
 			printf("No BFS filesystem on %s (magic=%08x)\n",
 				s->s_id,  le32_to_cpu(bfs_sb->s_magic));
 		goto out1;
 	}
 	if (BFS_UNCLEAN(bfs_sb, s) && !silent)
 		printf("%s is unclean, continuing\n", s->s_id);

 	s->s_magic = BFS_MAGIC;

 	if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end)) {
 		printf("Superblock is corrupted\n");
 		goto out1;
 	}

 	info->si_lasti = (le32_to_cpu(bfs_sb->s_start) - BFS_BSIZE) /
 					sizeof(struct bfs_inode)
 					+ BFS_ROOT_INO - 1;
 	imap_len = (info->si_lasti / 8) + 1;
 	info->si_imap = kzalloc(imap_len, GFP_KERNEL);
 	if (!info->si_imap)
 		goto out1;
 	for (i = 0; i < BFS_ROOT_INO; i++)
 		set_bit(i, info->si_imap);

 	s->s_op = &bfs_sops;
 	inode = bfs_iget(s, BFS_ROOT_INO);
 	if (IS_ERR(inode)) {
 		ret = PTR_ERR(inode);
 		goto out2;
 	}
 	s->s_root = d_alloc_root(inode);
 	if (!s->s_root) {
 		iput(inode);
 		ret = -ENOMEM;
 		goto out2;
 	}

 	info->si_blocks = (le32_to_cpu(bfs_sb->s_end) + 1) >> BFS_BSIZE_BITS;
 	info->si_freeb = (le32_to_cpu(bfs_sb->s_end) + 1
 			- le32_to_cpu(bfs_sb->s_start)) >> BFS_BSIZE_BITS;
 	info->si_freei = 0;
 	info->si_lf_eblk = 0;

 	/* can we read the last block? */
 	bh = sb_bread(s, info->si_blocks - 1);
 	if (!bh) {
 		printf("Last block not available: %lu\n", info->si_blocks - 1);
 		ret = -EIO;
 		goto out3;
 	}
 	brelse(bh);

 	bh = NULL;
 	for (i = BFS_ROOT_INO; i <= info->si_lasti; i++) {
 		struct bfs_inode *di;
 		int block = (i - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;
 		int off = (i - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;
 		unsigned long eblock;

 		if (!off) {
 			brelse(bh);
 			bh = sb_bread(s, block);
 		}

 		if (!bh)
 			continue;

 		di = (struct bfs_inode *)bh->b_data + off;

 		/* test if filesystem is not corrupted */

 		i_eoff = le32_to_cpu(di->i_eoffset);
 		i_sblock = le32_to_cpu(di->i_sblock);
 		i_eblock = le32_to_cpu(di->i_eblock);
 		s_size = le32_to_cpu(bfs_sb->s_end);

 		if (i_sblock > info->si_blocks ||
 			i_eblock > info->si_blocks ||
 			i_sblock > i_eblock ||
 			i_eoff > s_size ||
 			i_sblock * BFS_BSIZE > i_eoff) {

 			printf("Inode 0x%08x corrupted\n", i);

 			brelse(bh);
 			ret = -EIO;
 			goto out3;
 		}

 		if (!di->i_ino) {
 			info->si_freei++;
 			continue;
 		}
 		set_bit(i, info->si_imap);
 		info->si_freeb -= BFS_FILEBLOCKS(di);

 		eblock =  le32_to_cpu(di->i_eblock);
 		if (eblock > info->si_lf_eblk)
 			info->si_lf_eblk = eblock;
 	}
 	brelse(bh);
 	brelse(sbh);
 	dump_imap("read_super", s);
 	return 0;

 out3:
 	dput(s->s_root);
 	s->s_root = NULL;
 out2:
 	kfree(info->si_imap);
 out1:
 	brelse(sbh);
 out:
 	mutex_destroy(&info->bfs_lock);
 	kfree(info);
 	s->s_fs_info = NULL;
 	return ret;
 }

 static struct dentry *bfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	return mount_bdev(fs_type, flags, dev_name, data, bfs_fill_super);
 }

 static struct file_system_type bfs_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "bfs",
 	.mount		= bfs_mount,
 	.kill_sb	= kill_block_super,
 	.fs_flags	= FS_REQUIRES_DEV,
 };

 static int __init init_bfs_fs(void)
 {
 	int err = init_inodecache();
 	if (err)
 		goto out1;
         err = register_filesystem(&bfs_fs_type);
 	if (err)
 		goto out;
 	return 0;
 out:
 	destroy_inodecache();
 out1:
 	return err;
 }

 static void __exit exit_bfs_fs(void)
 {
 	unregister_filesystem(&bfs_fs_type);
 	destroy_inodecache();
 }

 module_init(init_bfs_fs)
 module_exit(exit_bfs_fs)
	/*
	* fs/bfs/inode.c
	* BFS superblock and inode operations.
	* Copyright (C) 1999-2006 Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
	* From fs/minix, Copyright (C) 1991, 1992 Linus Torvalds.
	*
	* Made endianness-clean by Andrew Stribblehill <ads@wompom.org>, 2005.
	*/

	#include <linux/module.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/buffer_head.h>
	#include <linux/vfs.h>
	#include <linux/writeback.h>
	#include <asm/uaccess.h>
	#include "bfs.h"

	MODULE_AUTHOR("Tigran Aivazian <tigran@aivazian.fsnet.co.uk>");
	MODULE_DESCRIPTION("SCO UnixWare BFS filesystem for Linux");
	MODULE_LICENSE("GPL");

	#undef DEBUG

	#ifdef DEBUG
	#define dprintf(x...) printf(x)
	#else
	#define dprintf(x...)
	#endif

	void dump_imap(const char prefix, struct super_block s);

	struct inode bfs_iget(struct super_block sb, unsigned long ino)
	{
	struct bfs_inode *di;
	struct inode *inode;
	struct buffer_head *bh;
	int block, off;

	inode = iget_locked(sb, ino);
	if (IS_ERR(inode))
	return ERR_PTR(-ENOMEM);
	if (!(inode->i_state & I_NEW))
	return inode;

	if ((ino < BFS_ROOT_INO) \|\| (ino > BFS_SB(inode->i_sb)->si_lasti)) {
	printf("Bad inode number %s:%08lx\n", inode->i_sb->s_id, ino);
	goto error;
	}

	block = (ino - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;
	bh = sb_bread(inode->i_sb, block);
	if (!bh) {
	printf("Unable to read inode %s:%08lx\n", inode->i_sb->s_id,
	ino);
	goto error;
	}

	off = (ino - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;
	di = (struct bfs_inode *)bh->b_data + off;

	inode->i_mode = 0x0000FFFF & le32_to_cpu(di->i_mode);
	if (le32_to_cpu(di->i_vtype) == BFS_VDIR) {
	inode->i_mode \|= S_IFDIR;
	inode->i_op = &bfs_dir_inops;
	inode->i_fop = &bfs_dir_operations;
	} else if (le32_to_cpu(di->i_vtype) == BFS_VREG) {
	inode->i_mode \|= S_IFREG;
	inode->i_op = &bfs_file_inops;
	inode->i_fop = &bfs_file_operations;
	inode->i_mapping->a_ops = &bfs_aops;
	}

	BFS_I(inode)->i_sblock = le32_to_cpu(di->i_sblock);
	BFS_I(inode)->i_eblock = le32_to_cpu(di->i_eblock);
	BFS_I(inode)->i_dsk_ino = le16_to_cpu(di->i_ino);
	inode->i_uid = le32_to_cpu(di->i_uid);
	inode->i_gid = le32_to_cpu(di->i_gid);
	inode->i_nlink = le32_to_cpu(di->i_nlink);
	inode->i_size = BFS_FILESIZE(di);
	inode->i_blocks = BFS_FILEBLOCKS(di);
	inode->i_atime.tv_sec = le32_to_cpu(di->i_atime);
	inode->i_mtime.tv_sec = le32_to_cpu(di->i_mtime);
	inode->i_ctime.tv_sec = le32_to_cpu(di->i_ctime);
	inode->i_atime.tv_nsec = 0;
	inode->i_mtime.tv_nsec = 0;
	inode->i_ctime.tv_nsec = 0;

	brelse(bh);
	unlock_new_inode(inode);
	return inode;

	error:
	iget_failed(inode);
	return ERR_PTR(-EIO);
	}

	static struct bfs_inode find_inode(struct super_block sb, u16 ino, struct buffer_head **p)
	{
	if ((ino < BFS_ROOT_INO) \|\| (ino > BFS_SB(sb)->si_lasti)) {
	printf("Bad inode number %s:%08x\n", sb->s_id, ino);
	return ERR_PTR(-EIO);
	}

	ino -= BFS_ROOT_INO;

	*p = sb_bread(sb, 1 + ino / BFS_INODES_PER_BLOCK);
	if (!*p) {
	printf("Unable to read inode %s:%08x\n", sb->s_id, ino);
	return ERR_PTR(-EIO);
	}

	return (struct bfs_inode )(p)->b_data + ino % BFS_INODES_PER_BLOCK;
	}

	static int bfs_write_inode(struct inode inode, struct writeback_control wbc)
	{
	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
	unsigned int ino = (u16)inode->i_ino;
	unsigned long i_sblock;
	struct bfs_inode *di;
	struct buffer_head *bh;
	int err = 0;

	dprintf("ino=%08x\n", ino);

	di = find_inode(inode->i_sb, ino, &bh);
	if (IS_ERR(di))
	return PTR_ERR(di);

	mutex_lock(&info->bfs_lock);

	if (ino == BFS_ROOT_INO)
	di->i_vtype = cpu_to_le32(BFS_VDIR);
	else
	di->i_vtype = cpu_to_le32(BFS_VREG);

	di->i_ino = cpu_to_le16(ino);
	di->i_mode = cpu_to_le32(inode->i_mode);
	di->i_uid = cpu_to_le32(inode->i_uid);
	di->i_gid = cpu_to_le32(inode->i_gid);
	di->i_nlink = cpu_to_le32(inode->i_nlink);
	di->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
	di->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
	di->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
	i_sblock = BFS_I(inode)->i_sblock;
	di->i_sblock = cpu_to_le32(i_sblock);
	di->i_eblock = cpu_to_le32(BFS_I(inode)->i_eblock);
	di->i_eoffset = cpu_to_le32(i_sblock * BFS_BSIZE + inode->i_size - 1);

	mark_buffer_dirty(bh);
	if (wbc->sync_mode == WB_SYNC_ALL) {
	sync_dirty_buffer(bh);
	if (buffer_req(bh) && !buffer_uptodate(bh))
	err = -EIO;
	}
	brelse(bh);
	mutex_unlock(&info->bfs_lock);
	return err;
	}

	static void bfs_evict_inode(struct inode *inode)
	{
	unsigned long ino = inode->i_ino;
	struct bfs_inode *di;
	struct buffer_head *bh;
	struct super_block *s = inode->i_sb;
	struct bfs_sb_info *info = BFS_SB(s);
	struct bfs_inode_info *bi = BFS_I(inode);

	dprintf("ino=%08lx\n", ino);

	truncate_inode_pages(&inode->i_data, 0);
	invalidate_inode_buffers(inode);
	end_writeback(inode);

	if (inode->i_nlink)
	return;

	di = find_inode(s, inode->i_ino, &bh);
	if (IS_ERR(di))
	return;

	mutex_lock(&info->bfs_lock);
	/* clear on-disk inode */
	memset(di, 0, sizeof(struct bfs_inode));
	mark_buffer_dirty(bh);
	brelse(bh);

	if (bi->i_dsk_ino) {
	if (bi->i_sblock)
	info->si_freeb += bi->i_eblock + 1 - bi->i_sblock;
	info->si_freei++;
	clear_bit(ino, info->si_imap);
	dump_imap("delete_inode", s);
	}

	/*
	* If this was the last file, make the previous block
	* "last block of the last file" even if there is no
	* real file there, saves us 1 gap.
	*/
	if (info->si_lf_eblk == bi->i_eblock)
	info->si_lf_eblk = bi->i_sblock - 1;
	mutex_unlock(&info->bfs_lock);
	}

	static void bfs_put_super(struct super_block *s)
	{
	struct bfs_sb_info *info = BFS_SB(s);

	if (!info)
	return;

	mutex_destroy(&info->bfs_lock);
	kfree(info->si_imap);
	kfree(info);
	s->s_fs_info = NULL;
	}

	static int bfs_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct super_block *s = dentry->d_sb;
	struct bfs_sb_info *info = BFS_SB(s);
	u64 id = huge_encode_dev(s->s_bdev->bd_dev);
	buf->f_type = BFS_MAGIC;
	buf->f_bsize = s->s_blocksize;
	buf->f_blocks = info->si_blocks;
	buf->f_bfree = buf->f_bavail = info->si_freeb;
	buf->f_files = info->si_lasti + 1 - BFS_ROOT_INO;
	buf->f_ffree = info->si_freei;
	buf->f_fsid.val[0] = (u32)id;
	buf->f_fsid.val[1] = (u32)(id >> 32);
	buf->f_namelen = BFS_NAMELEN;
	return 0;
	}

	static struct kmem_cache *bfs_inode_cachep;

	static struct inode bfs_alloc_inode(struct super_block sb)
	{
	struct bfs_inode_info *bi;
	bi = kmem_cache_alloc(bfs_inode_cachep, GFP_KERNEL);
	if (!bi)
	return NULL;
	return &bi->vfs_inode;
	}

	static void bfs_i_callback(struct rcu_head *head)
	{
	struct inode *inode = container_of(head, struct inode, i_rcu);
	INIT_LIST_HEAD(&inode->i_dentry);
	kmem_cache_free(bfs_inode_cachep, BFS_I(inode));
	}

	static void bfs_destroy_inode(struct inode *inode)
	{
	call_rcu(&inode->i_rcu, bfs_i_callback);
	}

	static void init_once(void *foo)
	{
	struct bfs_inode_info *bi = foo;

	inode_init_once(&bi->vfs_inode);
	}

	static int init_inodecache(void)
	{
	bfs_inode_cachep = kmem_cache_create("bfs_inode_cache",
	sizeof(struct bfs_inode_info),
	0, (SLAB_RECLAIM_ACCOUNT\|
	SLAB_MEM_SPREAD),
	init_once);
	if (bfs_inode_cachep == NULL)
	return -ENOMEM;
	return 0;
	}

	static void destroy_inodecache(void)
	{
	kmem_cache_destroy(bfs_inode_cachep);
	}

	static const struct super_operations bfs_sops = {
	.alloc_inode = bfs_alloc_inode,
	.destroy_inode = bfs_destroy_inode,
	.write_inode = bfs_write_inode,
	.evict_inode = bfs_evict_inode,
	.put_super = bfs_put_super,
	.statfs = bfs_statfs,
	};

	void dump_imap(const char prefix, struct super_block s)
	{
	#ifdef DEBUG
	int i;
	char tmpbuf = (char )get_zeroed_page(GFP_KERNEL);

	if (!tmpbuf)
	return;
	for (i = BFS_SB(s)->si_lasti; i >= 0; i--) {
	if (i > PAGE_SIZE - 100) break;
	if (test_bit(i, BFS_SB(s)->si_imap))
	strcat(tmpbuf, "1");
	else
	strcat(tmpbuf, "0");
	}
	printf("BFS-fs: %s: lasti=%08lx <%s>\n",
	prefix, BFS_SB(s)->si_lasti, tmpbuf);
	free_page((unsigned long)tmpbuf);
	#endif
	}

	static int bfs_fill_super(struct super_block s, void data, int silent)
	{
	struct buffer_head bh, sbh;
	struct bfs_super_block *bfs_sb;
	struct inode *inode;
	unsigned i, imap_len;
	struct bfs_sb_info *info;
	int ret = -EINVAL;
	unsigned long i_sblock, i_eblock, i_eoff, s_size;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info)
	return -ENOMEM;
	mutex_init(&info->bfs_lock);
	s->s_fs_info = info;

	sb_set_blocksize(s, BFS_BSIZE);

	sbh = sb_bread(s, 0);
	if (!sbh)
	goto out;
	bfs_sb = (struct bfs_super_block *)sbh->b_data;
	if (le32_to_cpu(bfs_sb->s_magic) != BFS_MAGIC) {
	if (!silent)
	printf("No BFS filesystem on %s (magic=%08x)\n",
	s->s_id, le32_to_cpu(bfs_sb->s_magic));
	goto out1;
	}
	if (BFS_UNCLEAN(bfs_sb, s) && !silent)
	printf("%s is unclean, continuing\n", s->s_id);

	s->s_magic = BFS_MAGIC;

	if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end)) {
	printf("Superblock is corrupted\n");
	goto out1;
	}

	info->si_lasti = (le32_to_cpu(bfs_sb->s_start) - BFS_BSIZE) /
	sizeof(struct bfs_inode)
	+ BFS_ROOT_INO - 1;
	imap_len = (info->si_lasti / 8) + 1;
	info->si_imap = kzalloc(imap_len, GFP_KERNEL);
	if (!info->si_imap)
	goto out1;
	for (i = 0; i < BFS_ROOT_INO; i++)
	set_bit(i, info->si_imap);

	s->s_op = &bfs_sops;
	inode = bfs_iget(s, BFS_ROOT_INO);
	if (IS_ERR(inode)) {
	ret = PTR_ERR(inode);
	goto out2;
	}
	s->s_root = d_alloc_root(inode);
	if (!s->s_root) {
	iput(inode);
	ret = -ENOMEM;
	goto out2;
	}

	info->si_blocks = (le32_to_cpu(bfs_sb->s_end) + 1) >> BFS_BSIZE_BITS;
	info->si_freeb = (le32_to_cpu(bfs_sb->s_end) + 1
	- le32_to_cpu(bfs_sb->s_start)) >> BFS_BSIZE_BITS;
	info->si_freei = 0;
	info->si_lf_eblk = 0;

	/* can we read the last block? */
	bh = sb_bread(s, info->si_blocks - 1);
	if (!bh) {
	printf("Last block not available: %lu\n", info->si_blocks - 1);
	ret = -EIO;
	goto out3;
	}
	brelse(bh);

	bh = NULL;
	for (i = BFS_ROOT_INO; i <= info->si_lasti; i++) {
	struct bfs_inode *di;
	int block = (i - BFS_ROOT_INO) / BFS_INODES_PER_BLOCK + 1;
	int off = (i - BFS_ROOT_INO) % BFS_INODES_PER_BLOCK;
	unsigned long eblock;

	if (!off) {
	brelse(bh);
	bh = sb_bread(s, block);
	}

	if (!bh)
	continue;

	di = (struct bfs_inode *)bh->b_data + off;

	/* test if filesystem is not corrupted */

	i_eoff = le32_to_cpu(di->i_eoffset);
	i_sblock = le32_to_cpu(di->i_sblock);
	i_eblock = le32_to_cpu(di->i_eblock);
	s_size = le32_to_cpu(bfs_sb->s_end);

	if (i_sblock > info->si_blocks \|\|
	i_eblock > info->si_blocks \|\|
	i_sblock > i_eblock \|\|
	i_eoff > s_size \|\|
	i_sblock * BFS_BSIZE > i_eoff) {

	printf("Inode 0x%08x corrupted\n", i);

	brelse(bh);
	ret = -EIO;
	goto out3;
	}

	if (!di->i_ino) {
	info->si_freei++;
	continue;
	}
	set_bit(i, info->si_imap);
	info->si_freeb -= BFS_FILEBLOCKS(di);

	eblock = le32_to_cpu(di->i_eblock);
	if (eblock > info->si_lf_eblk)
	info->si_lf_eblk = eblock;
	}
	brelse(bh);
	brelse(sbh);
	dump_imap("read_super", s);
	return 0;

	out3:
	dput(s->s_root);
	s->s_root = NULL;
	out2:
	kfree(info->si_imap);
	out1:
	brelse(sbh);
	out:
	mutex_destroy(&info->bfs_lock);
	kfree(info);
	s->s_fs_info = NULL;
	return ret;
	}

	static struct dentry bfs_mount(struct file_system_type fs_type,
	int flags, const char dev_name, void data)
	{
	return mount_bdev(fs_type, flags, dev_name, data, bfs_fill_super);
	}

	static struct file_system_type bfs_fs_type = {
	.owner = THIS_MODULE,
	.name = "bfs",
	.mount = bfs_mount,
	.kill_sb = kill_block_super,
	.fs_flags = FS_REQUIRES_DEV,
	};

	static int __init init_bfs_fs(void)
	{
	int err = init_inodecache();
	if (err)
	goto out1;
	err = register_filesystem(&bfs_fs_type);
	if (err)
	goto out;
	return 0;
	out:
	destroy_inodecache();
	out1:
	return err;
	}

	static void __exit exit_bfs_fs(void)
	{
	unregister_filesystem(&bfs_fs_type);
	destroy_inodecache();
	}

	module_init(init_bfs_fs)
	module_exit(exit_bfs_fs)