Date:	Tue, 15 Apr 2008 20:03:50 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	hch@...radead.org
CC:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	akpm@...ux-foundation.org, me@...copeland.com
Subject: Re: [PATCH 2/7] omfs: add inode routines

Hmm, looks like error handling needs a makeover if this is really to
become example code.  See comments inline.

Somebody said this is fun?  Please do a proper review of this patchset
then, thank you.  ("Political" eh?  Now I think *that* is really
insulting to Andrew)

Miklos



> diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c
> new file mode 100644
> index 0000000..92d794f
> --- /dev/null
> +++ b/fs/omfs/inode.c
> @@ -0,0 +1,439 @@
> +/*
> + * Optimized MPEG FS - inode and super operations.
> + * Copyright (C) 2006 Bob Copeland <me@...copeland.com>
> + * Released under GPL v2.
> + */
> +#include <linux/version.h>
> +#include <linux/module.h>
> +#include <linux/sched.h>
> +#include <linux/fs.h>
> +#include <linux/vfs.h>
> +#include <linux/buffer_head.h>
> +#include <linux/vmalloc.h>
> +#include "omfs.h"
> +
> +MODULE_AUTHOR("Bob Copeland <me@...copeland.com>");
> +MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
> +MODULE_LICENSE("GPL");
> +
> +struct inode *omfs_new_inode(struct inode *dir, int mode)
> +{
> +	struct inode *inode;
> +	u64 new_block;
> +	int res;
> +	int len;
> +	struct omfs_sb_info *sbi = OMFS_SB(dir->i_sb);
> +
> +	inode = new_inode(dir->i_sb);
> +	if (!inode)
> +		return ERR_PTR(-ENOMEM);
> +
> +	res = omfs_allocate_range(dir->i_sb, sbi->s_mirrors, sbi->s_mirrors,
> +			&new_block, &len);
> +	if (res)
> +		return ERR_PTR(res);

Leaks inode.

> +
> +	inode->i_ino = new_block;
> +	inode->i_mode = mode;
> +	inode->i_uid = current->fsuid;
> +	inode->i_gid = current->fsgid;
> +	inode->i_blocks = 0;
> +	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;
> +		inode->i_nlink++;
> +		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;
> +}
> +
> +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;
> +	unsigned int block;
> +	u64 ctime;
> +	int i;
> +	int ret = 0;
> +
> +	/* get current inode since we may have written sibling ptrs etc. */
> +	block = clus_to_blk(sbi, inode->i_ino);
> +	bh = sb_bread(inode->i_sb, block);
> +	if (!bh) {
> +		ret = -EIO;
> +		goto out_nobh;
> +	}

This form is preferred:

	ret = -EIO;
	if (!bh)
		goto out_nobh;


> +
> +	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);
> +		ret = -EIO;
> +		goto out;

Ditto.  If err is the same as assigned previously it doesn't need to
be assigned again, so that even less lines.

> +	}
> +
> +	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);
> +
> +	if (omfs_update_checksums(oi) != 0) {
> +		ret = -EIO;
> +		goto out;

Ditto.

> +	}
> +
> +	mark_buffer_dirty(bh);
> +	if (wait) {
> +		sync_dirty_buffer(bh);
> +		if (buffer_req(bh) && !buffer_uptodate(bh))
> +			ret = -EIO;

Hmm, here it sets ret, but doesn't exit.  Deliberate?

> +	}
> +
> +	/* if mirroring writes, copy to next fsblock */
> +	for (i = 1; i < sbi->s_mirrors; i++) {
> +		bh2 = sb_bread(inode->i_sb, block + i *
> +			(sbi->s_blocksize / sbi->s_sys_blocksize));
> +		if (!bh2) {
> +			brelse(bh2);
> +			ret = -EIO;
> +			goto out;

Ditto1.

> +		}
> +		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))
> +				ret = -EIO;

Ditto2?

> +		}
> +		brelse(bh2);
> +	}
> +out:
> +	brelse(bh);
> +out_nobh:
> +	return ret;
> +}
> +
> +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_delete_inode(struct inode *inode)
> +{
> +	truncate_inode_pages(&inode->i_data, 0);
> +
> +	if (S_ISREG(inode->i_mode)) {
> +		inode->i_size = 0;
> +		omfs_shrink_inode(inode);
> +	}
> +
> +	omfs_clear_range(inode->i_sb, inode->i_ino, 2);
> +	clear_inode(inode);
> +}
> +
> +struct inode *omfs_iget(struct super_block *sb, ino_t ino)
> +{
> +	struct omfs_inode *oi;
> +	struct buffer_head *bh;
> +	unsigned int block;
> +	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;
> +
> +	block = clus_to_blk(OMFS_SB(inode->i_sb), ino);
> +	bh = sb_bread(inode->i_sb, block);
> +	if (!bh) {
> +		iget_failed(inode);
> +		return ERR_PTR(-EIO);

Should be:

	if (!bh)
		goto iget_failed;
...

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

> +	}
> +
> +	oi = (struct omfs_inode *)bh->b_data;
> +
> +	/* check self */
> +	if (ino != be64_to_cpu(oi->i_head.h_self)) {
> +		iget_failed(inode);
> +		return ERR_PTR(-EIO);

Leaks bh.  See above.

> +	}
> +
> +	inode->i_uid = 0;
> +	inode->i_gid = 0;
> +
> +	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_IRUGO | S_IWUGO | S_IXUGO;
> +		inode->i_op = &omfs_dir_inops;
> +		inode->i_fop = &omfs_dir_operations;
> +		inode->i_size = be32_to_cpu(oi->i_head.h_body_size) +
> +			sizeof(struct omfs_header);
> +		inode->i_nlink++;
> +		break;
> +	case OMFS_FILE:
> +		inode->i_mode = S_IFREG | S_IRUGO | S_IWUGO;
> +		inode->i_fop = &omfs_file_operations;
> +		inode->i_size = be64_to_cpu(oi->i_size);
> +		break;
> +	}
> +	brelse(bh);
> +	unlock_new_inode(inode);
> +	return inode;
> +}
> +
> +
> +static void omfs_put_super(struct super_block *sb)
> +{
> +	struct omfs_sb_info *sbi = OMFS_SB(sb);
> +	if (sbi) {
> +		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);
> +	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_bfree = buf->f_bavail = buf->f_ffree =
> +		omfs_count_free(s);
> +	return 0;
> +}
> +
> +static struct super_operations omfs_sops = {
> +	.write_inode	= omfs_write_inode,
> +	.delete_inode	= omfs_delete_inode,
> +	.put_super	= omfs_put_super,
> +	.statfs		= omfs_statfs,
> +};
> +
> +/*
> + * 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 = (sbi->s_num_blocks + 7) / 8;
> +	array_size = (bitmap_size + sb->s_blocksize - 1) / sb->s_blocksize;
> +
> +	sbi->s_imap_size = array_size;
> +	sbi->s_imap = kzalloc(array_size * sizeof(unsigned long *), GFP_KERNEL);
> +	if (!sbi->s_imap)
> +		return -ENOMEM;
> +
> +	block = clus_to_blk(sbi, sbi->s_bitmap_ino);
> +	ptr = sbi->s_imap;
> +	for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
> +		bh = sb_bread(sb, block++);
> +		if (!bh)
> +			goto nomem;
> +		*ptr = kmalloc(sb->s_blocksize, GFP_KERNEL);
> +		if (!*ptr)
> +			goto nomem;

Leaks bh.

> +		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++;
> +	}
> +	return 0;
> +nomem:
> +	for (count = 0; count < array_size; count++)
> +		kfree(sbi->s_imap[count]);
> +
> +	kfree(sbi->s_imap);
> +	sbi->s_imap = NULL;
> +	return -ENOMEM;
> +}
> +
> +static void set_block_shift(struct omfs_sb_info *sbi)
> +{
> +	unsigned int scale = sbi->s_blocksize / sbi->s_sys_blocksize;
> +	sbi->s_block_shift = 0;
> +	for (scale >>= 1; scale; scale >>= 1)
> +		sbi->s_block_shift++;
> +}
> +
> +static int omfs_fill_super(struct super_block *sb, void *data, int silent)
> +{
> +	struct buffer_head *bh = NULL, *bh2 = NULL;
> +	struct omfs_super_block *omfs_sb;
> +	struct omfs_root_block *omfs_rb;
> +	struct omfs_sb_info *sbi;
> +	struct inode *root;
> +	sector_t start;
> +	int ret = 0;
> +
> +	sbi = kzalloc(sizeof(struct omfs_sb_info), GFP_KERNEL);
> +	if (!sbi)
> +		return -ENOMEM;
> +	sb->s_fs_info = sbi;
> +
> +	sb->s_maxbytes = 0xffffffff;
> +
> +	sb_set_blocksize(sb, 0x200);
> +
> +	bh = sb_bread(sb, 0);
> +	if (!bh)
> +		goto out;
> +
> +	omfs_sb = (struct omfs_super_block *)bh->b_data;
> +
> +	if (be32_to_cpu(omfs_sb->s_magic) != OMFS_MAGIC) {
> +		if (!silent)
> +			printk(KERN_ERR "omfs: Invalid superblock (%x)\n",
> +				   omfs_sb->s_magic);
> +		goto out;
> +	}
> +	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);
> +
> +	/*
> +	 * 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.
> +	 */
> +	set_block_shift(sbi);
> +
> +	start = clus_to_blk(sbi, be64_to_cpu(omfs_sb->s_root_block));
> +	bh2 = sb_bread(sb, start);
> +	if (!bh2)
> +		goto out;
> +
> +	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);
> +
> +	ret = omfs_get_imap(sb);
> +	if (ret)
> +		goto end;
> +
> +	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 end;
> +	}
> +
> +	sb->s_root = d_alloc_root(root);
> +	if (!sb->s_root) {
> +		iput(root);
> +		goto out;
> +	}
> +	printk(KERN_DEBUG "omfs: Mounted volume %s\n", omfs_rb->r_name);
> +	goto end;
> +
> +out:
> +	ret = -EINVAL;
> +
> +end:
> +	if (bh2)
> +		brelse(bh2);
> +	if (bh)
> +		brelse(bh);

This is weird.  This should be done by jumping to the proper label
between the brleses.

> +	return ret;
> +}
> +
> +static int omfs_get_sb(struct file_system_type *fs_type,
> +			int flags, const char *dev_name,
> +			void *data, struct vfsmount *m)
> +{
> +	return get_sb_bdev(fs_type, flags, dev_name, data, omfs_fill_super, m);
> +}
> +
> +static struct file_system_type omfs_fs_type = {
> +	.owner = THIS_MODULE,
> +	.name = "omfs",
> +	.get_sb = omfs_get_sb,
> +	.kill_sb = kill_block_super,
> +	.fs_flags = FS_REQUIRES_DEV,
> +};
> +
> +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);
> -- 
> 1.5.4.2
> 
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