namei.c

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/*
 *  linux/fs/sysv/namei.c
 *
 *  minix/namei.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  coh/namei.c
 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 *
 *  sysv/namei.c
 *  Copyright (C) 1993  Bruno Haible
 *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
 */

#include <linux/fs.h>
#include <linux/sysv_fs.h>
#include <linux/pagemap.h>

static inline void inc_count(struct inode *inode)
{
	inode->i_nlink++;
	mark_inode_dirty(inode);
}

static inline void dec_count(struct inode *inode)
{
	inode->i_nlink--;
	mark_inode_dirty(inode);
}

static int add_nondir(struct dentry *dentry, struct inode *inode)
{
	int err = sysv_add_link(dentry, inode);
	if (!err) {
		d_instantiate(dentry, inode);
		return 0;
	}
	dec_count(inode);
	iput(inode);
	return err;
}

static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
{
	unsigned long hash;
	int i;
	const unsigned char *name;

	i = SYSV_NAMELEN;
	if (i >= qstr->len)
		return 0;
	/* Truncate the name in place, avoids having to define a compare
	   function. */
	qstr->len = i;
	name = qstr->name;
	hash = init_name_hash();
	while (i--)
		hash = partial_name_hash(*name++, hash);
	qstr->hash = end_name_hash(hash);
	return 0;
}

struct dentry_operations sysv_dentry_operations = {
	d_hash:		sysv_hash,
};

static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry)
{
	struct inode * inode = NULL;
	ino_t ino;

	dentry->d_op = dir->i_sb->s_root->d_op;
	if (dentry->d_name.len > SYSV_NAMELEN)
		return ERR_PTR(-ENAMETOOLONG);
	ino = sysv_inode_by_name(dentry);

	if (ino) {
		inode = iget(dir->i_sb, ino);
		if (!inode) 
			return ERR_PTR(-EACCES);
	}
	d_add(dentry, inode);
	return NULL;
}

static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, int rdev)
{
	struct inode * inode = sysv_new_inode(dir, mode);
	int err = PTR_ERR(inode);

	if (!IS_ERR(inode)) {
		sysv_set_inode(inode, rdev);
		mark_inode_dirty(inode);
		err = add_nondir(dentry, inode);
	}
	return err;
}

static int sysv_create(struct inode * dir, struct dentry * dentry, int mode)
{
	return sysv_mknod(dir, dentry, mode, 0);
}

static int sysv_symlink(struct inode * dir, struct dentry * dentry, 
	const char * symname)
{
	int err = -ENAMETOOLONG;
	int l = strlen(symname)+1;
	struct inode * inode;

	if (l > dir->i_sb->s_blocksize)
		goto out;

	inode = sysv_new_inode(dir, S_IFLNK|0777);
	err = PTR_ERR(inode);
	if (IS_ERR(inode))
		goto out;
	
	sysv_set_inode(inode, 0);
	err = block_symlink(inode, symname, l);
	if (err)
		goto out_fail;

	mark_inode_dirty(inode);
	err = add_nondir(dentry, inode);
out:
	return err;

out_fail:
	dec_count(inode);
	iput(inode);
	goto out;
}

static int sysv_link(struct dentry * old_dentry, struct inode * dir, 
	struct dentry * dentry)
{
	struct inode *inode = old_dentry->d_inode;

	if (S_ISDIR(inode->i_mode))
		return -EPERM;

	if (inode->i_nlink >= inode->i_sb->sv_link_max)
		return -EMLINK;

	inode->i_ctime = CURRENT_TIME;
	inc_count(inode);
	atomic_inc(&inode->i_count);

	return add_nondir(dentry, inode);
}

static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
{
	struct inode * inode;
	int err = -EMLINK;

	if (dir->i_nlink >= dir->i_sb->sv_link_max) 
		goto out;
	inc_count(dir);

	inode = sysv_new_inode(dir, S_IFDIR|mode);
	err = PTR_ERR(inode);
	if (IS_ERR(inode))
		goto out_dir;

	sysv_set_inode(inode, 0);

	inc_count(inode);

	err = sysv_make_empty(inode, dir);
	if (err)
		goto out_fail;

	err = sysv_add_link(dentry, inode);
	if (err)
		goto out_fail;

        d_instantiate(dentry, inode);
out:
	return err;

out_fail:
	dec_count(inode);
	dec_count(inode);
	iput(inode);
out_dir:
	dec_count(dir);
	goto out;
}

static int sysv_unlink(struct inode * dir, struct dentry * dentry)
{
	struct inode * inode = dentry->d_inode;
	struct page * page;
	struct sysv_dir_entry * de;
	int err = -ENOENT;

	de = sysv_find_entry(dentry, &page);
	if (!de)
		goto out;

	err = sysv_delete_entry (de, page);
	if (err)
		goto out;

	inode->i_ctime = dir->i_ctime;
	dec_count(inode);
out:
	return err;
}

static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
{
	struct inode *inode = dentry->d_inode;
	int err = -ENOTEMPTY;

	if (sysv_empty_dir(inode)) {
		err = sysv_unlink(dir, dentry);
		if (!err) {
			inode->i_size = 0;
			dec_count(inode);
			dec_count(dir);
		}
	}
	return err;
}

/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
		  struct inode * new_dir, struct dentry * new_dentry)
{
	struct inode * old_inode = old_dentry->d_inode;
	struct inode * new_inode = new_dentry->d_inode;
	struct page * dir_page = NULL;
	struct sysv_dir_entry * dir_de = NULL;
	struct page * old_page;
	struct sysv_dir_entry * old_de;
	int err = -ENOENT;

	old_de = sysv_find_entry(old_dentry, &old_page);
	if (!old_de)
		goto out;

	if (S_ISDIR(old_inode->i_mode)) {
		err = -EIO;
		dir_de = sysv_dotdot(old_inode, &dir_page);
		if (!dir_de)
			goto out_old;
	}

	if (new_inode) {
		struct page * new_page;
		struct sysv_dir_entry * new_de;

		err = -ENOTEMPTY;
		if (dir_de && !sysv_empty_dir(new_inode))
			goto out_dir;

		err = -ENOENT;
		new_de = sysv_find_entry(new_dentry, &new_page);
		if (!new_de)
			goto out_dir;
		inc_count(old_inode);
		sysv_set_link(new_de, new_page, old_inode);
		new_inode->i_ctime = CURRENT_TIME;
		if (dir_de)
			new_inode->i_nlink--;
		dec_count(new_inode);
	} else {
		if (dir_de) {
			err = -EMLINK;
			if (new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
				goto out_dir;
		}
		inc_count(old_inode);
		err = sysv_add_link(new_dentry, old_inode);
		if (err) {
			dec_count(old_inode);
			goto out_dir;
		}
		if (dir_de)
			inc_count(new_dir);
	}

	sysv_delete_entry(old_de, old_page);
	dec_count(old_inode);

	if (dir_de) {
		sysv_set_link(dir_de, dir_page, new_dir);
		dec_count(old_dir);
	}
	return 0;

out_dir:
	if (dir_de) {
		kunmap(dir_page);
		page_cache_release(dir_page);
	}
out_old:
	kunmap(old_page);
	page_cache_release(old_page);
out:
	return err;
}

/*
 * directories can handle most operations...
 */
struct inode_operations sysv_dir_inode_operations = {
	create:		sysv_create,
	lookup:		sysv_lookup,
	link:		sysv_link,
	unlink:		sysv_unlink,
	symlink:	sysv_symlink,
	mkdir:		sysv_mkdir,
	rmdir:		sysv_rmdir,
	mknod:		sysv_mknod,
	rename:		sysv_rename,
};