export.c

linux 内核源代码

	/* flags */
	err = get_int(&mesg, &an_int);
	if (err == -ENOENT) {
		err = 0;
		set_bit(CACHE_NEGATIVE, &exp.h.flags);
	} else {
		if (err || an_int < 0) goto out;	
		exp.ex_flags= an_int;
	
		/* anon uid */
		err = get_int(&mesg, &an_int);
		if (err) goto out;
		exp.ex_anon_uid= an_int;

		/* anon gid */
		err = get_int(&mesg, &an_int);
		if (err) goto out;
		exp.ex_anon_gid= an_int;

		/* fsid */
		err = get_int(&mesg, &an_int);
		if (err) goto out;
		exp.ex_fsid = an_int;

		while ((len = qword_get(&mesg, buf, PAGE_SIZE)) > 0) {
			if (strcmp(buf, "fsloc") == 0)
				err = fsloc_parse(&mesg, buf, &exp.ex_fslocs);
			else if (strcmp(buf, "uuid") == 0) {
				/* expect a 16 byte uuid encoded as \xXXXX... */
				len = qword_get(&mesg, buf, PAGE_SIZE);
				if (len != 16)
					err  = -EINVAL;
				else {
					exp.ex_uuid =
						kmemdup(buf, 16, GFP_KERNEL);
					if (exp.ex_uuid == NULL)
						err = -ENOMEM;
				}
			} else if (strcmp(buf, "secinfo") == 0)
				err = secinfo_parse(&mesg, buf, &exp);
			else
				/* quietly ignore unknown words and anything
				 * following. Newer user-space can try to set
				 * new values, then see what the result was.
				 */
				break;
			if (err)
				goto out;
		}

		err = check_export(nd.dentry->d_inode, exp.ex_flags,
				   exp.ex_uuid);
		if (err) goto out;
	}

	expp = svc_export_lookup(&exp);
	if (expp)
		expp = svc_export_update(&exp, expp);
	else
		err = -ENOMEM;
	cache_flush();
	if (expp == NULL)
		err = -ENOMEM;
	else
		exp_put(expp);
 out:
	nfsd4_fslocs_free(&exp.ex_fslocs);
	kfree(exp.ex_uuid);
 	kfree(exp.ex_path);
	if (nd.dentry)
		path_release(&nd);
 out_no_path:
	if (dom)
		auth_domain_put(dom);
	kfree(buf);
	return err;
}

static void exp_flags(struct seq_file *m, int flag, int fsid,
		uid_t anonu, uid_t anong, struct nfsd4_fs_locations *fslocs);
static void show_secinfo(struct seq_file *m, struct svc_export *exp);

static int svc_export_show(struct seq_file *m,
			   struct cache_detail *cd,
			   struct cache_head *h)
{
	struct svc_export *exp ;

	if (h ==NULL) {
		seq_puts(m, "#path domain(flags)\n");
		return 0;
	}
	exp = container_of(h, struct svc_export, h);
	seq_path(m, exp->ex_mnt, exp->ex_dentry, " \t\n\\");
	seq_putc(m, '\t');
	seq_escape(m, exp->ex_client->name, " \t\n\\");
	seq_putc(m, '(');
	if (test_bit(CACHE_VALID, &h->flags) && 
	    !test_bit(CACHE_NEGATIVE, &h->flags)) {
		exp_flags(m, exp->ex_flags, exp->ex_fsid,
			  exp->ex_anon_uid, exp->ex_anon_gid, &exp->ex_fslocs);
		if (exp->ex_uuid) {
			int i;
			seq_puts(m, ",uuid=");
			for (i=0; i<16; i++) {
				if ((i&3) == 0 && i)
					seq_putc(m, ':');
				seq_printf(m, "%02x", exp->ex_uuid[i]);
			}
		}
		show_secinfo(m, exp);
	}
	seq_puts(m, ")\n");
	return 0;
}
static int svc_export_match(struct cache_head *a, struct cache_head *b)
{
	struct svc_export *orig = container_of(a, struct svc_export, h);
	struct svc_export *new = container_of(b, struct svc_export, h);
	return orig->ex_client == new->ex_client &&
		orig->ex_dentry == new->ex_dentry &&
		orig->ex_mnt == new->ex_mnt;
}

static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)
{
	struct svc_export *new = container_of(cnew, struct svc_export, h);
	struct svc_export *item = container_of(citem, struct svc_export, h);

	kref_get(&item->ex_client->ref);
	new->ex_client = item->ex_client;
	new->ex_dentry = dget(item->ex_dentry);
	new->ex_mnt = mntget(item->ex_mnt);
	new->ex_path = NULL;
	new->ex_fslocs.locations = NULL;
	new->ex_fslocs.locations_count = 0;
	new->ex_fslocs.migrated = 0;
}

static void export_update(struct cache_head *cnew, struct cache_head *citem)
{
	struct svc_export *new = container_of(cnew, struct svc_export, h);
	struct svc_export *item = container_of(citem, struct svc_export, h);
	int i;

	new->ex_flags = item->ex_flags;
	new->ex_anon_uid = item->ex_anon_uid;
	new->ex_anon_gid = item->ex_anon_gid;
	new->ex_fsid = item->ex_fsid;
	new->ex_uuid = item->ex_uuid;
	item->ex_uuid = NULL;
	new->ex_path = item->ex_path;
	item->ex_path = NULL;
	new->ex_fslocs.locations = item->ex_fslocs.locations;
	item->ex_fslocs.locations = NULL;
	new->ex_fslocs.locations_count = item->ex_fslocs.locations_count;
	item->ex_fslocs.locations_count = 0;
	new->ex_fslocs.migrated = item->ex_fslocs.migrated;
	item->ex_fslocs.migrated = 0;
	new->ex_nflavors = item->ex_nflavors;
	for (i = 0; i < MAX_SECINFO_LIST; i++) {
		new->ex_flavors[i] = item->ex_flavors[i];
	}
}

static struct cache_head *svc_export_alloc(void)
{
	struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL);
	if (i)
		return &i->h;
	else
		return NULL;
}

struct cache_detail svc_export_cache = {
	.owner		= THIS_MODULE,
	.hash_size	= EXPORT_HASHMAX,
	.hash_table	= export_table,
	.name		= "nfsd.export",
	.cache_put	= svc_export_put,
	.cache_request	= svc_export_request,
	.cache_parse	= svc_export_parse,
	.cache_show	= svc_export_show,
	.match		= svc_export_match,
	.init		= svc_export_init,
	.update		= export_update,
	.alloc		= svc_export_alloc,
};

static struct svc_export *
svc_export_lookup(struct svc_export *exp)
{
	struct cache_head *ch;
	int hash;
	hash = hash_ptr(exp->ex_client, EXPORT_HASHBITS);
	hash ^= hash_ptr(exp->ex_dentry, EXPORT_HASHBITS);
	hash ^= hash_ptr(exp->ex_mnt, EXPORT_HASHBITS);

	ch = sunrpc_cache_lookup(&svc_export_cache, &exp->h,
				 hash);
	if (ch)
		return container_of(ch, struct svc_export, h);
	else
		return NULL;
}

static struct svc_export *
svc_export_update(struct svc_export *new, struct svc_export *old)
{
	struct cache_head *ch;
	int hash;
	hash = hash_ptr(old->ex_client, EXPORT_HASHBITS);
	hash ^= hash_ptr(old->ex_dentry, EXPORT_HASHBITS);
	hash ^= hash_ptr(old->ex_mnt, EXPORT_HASHBITS);

	ch = sunrpc_cache_update(&svc_export_cache, &new->h,
				 &old->h,
				 hash);
	if (ch)
		return container_of(ch, struct svc_export, h);
	else
		return NULL;
}


static struct svc_expkey *
exp_find_key(svc_client *clp, int fsid_type, u32 *fsidv, struct cache_req *reqp)
{
	struct svc_expkey key, *ek;
	int err;
	
	if (!clp)
		return ERR_PTR(-ENOENT);

	key.ek_client = clp;
	key.ek_fsidtype = fsid_type;
	memcpy(key.ek_fsid, fsidv, key_len(fsid_type));

	ek = svc_expkey_lookup(&key);
	if (ek == NULL)
		return ERR_PTR(-ENOMEM);
	err = cache_check(&svc_expkey_cache, &ek->h, reqp);
	if (err)
		return ERR_PTR(err);
	return ek;
}

static int exp_set_key(svc_client *clp, int fsid_type, u32 *fsidv,
		       struct svc_export *exp)
{
	struct svc_expkey key, *ek;

	key.ek_client = clp;
	key.ek_fsidtype = fsid_type;
	memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
	key.ek_mnt = exp->ex_mnt;
	key.ek_dentry = exp->ex_dentry;
	key.h.expiry_time = NEVER;
	key.h.flags = 0;

	ek = svc_expkey_lookup(&key);
	if (ek)
		ek = svc_expkey_update(&key,ek);
	if (ek) {
		cache_put(&ek->h, &svc_expkey_cache);
		return 0;
	}
	return -ENOMEM;
}

/*
 * Find the client's export entry matching xdev/xino.
 */
static inline struct svc_expkey *
exp_get_key(svc_client *clp, dev_t dev, ino_t ino)
{
	u32 fsidv[3];
	
	if (old_valid_dev(dev)) {
		mk_fsid(FSID_DEV, fsidv, dev, ino, 0, NULL);
		return exp_find_key(clp, FSID_DEV, fsidv, NULL);
	}
	mk_fsid(FSID_ENCODE_DEV, fsidv, dev, ino, 0, NULL);
	return exp_find_key(clp, FSID_ENCODE_DEV, fsidv, NULL);
}

/*
 * Find the client's export entry matching fsid
 */
static inline struct svc_expkey *
exp_get_fsid_key(svc_client *clp, int fsid)
{
	u32 fsidv[2];

	mk_fsid(FSID_NUM, fsidv, 0, 0, fsid, NULL);

	return exp_find_key(clp, FSID_NUM, fsidv, NULL);
}

static svc_export *exp_get_by_name(svc_client *clp, struct vfsmount *mnt,
				   struct dentry *dentry,
				   struct cache_req *reqp)
{
	struct svc_export *exp, key;
	int err;
	
	if (!clp)
		return ERR_PTR(-ENOENT);

	key.ex_client = clp;
	key.ex_mnt = mnt;
	key.ex_dentry = dentry;

	exp = svc_export_lookup(&key);
	if (exp == NULL)
		return ERR_PTR(-ENOMEM);
	err = cache_check(&svc_export_cache, &exp->h, reqp);
	if (err)
		return ERR_PTR(err);
	return exp;
}

/*
 * Find the export entry for a given dentry.
 */
static struct svc_export *exp_parent(svc_client *clp, struct vfsmount *mnt,
				     struct dentry *dentry,
				     struct cache_req *reqp)
{
	svc_export *exp;

	dget(dentry);
	exp = exp_get_by_name(clp, mnt, dentry, reqp);

	while (PTR_ERR(exp) == -ENOENT && !IS_ROOT(dentry)) {
		struct dentry *parent;

		parent = dget_parent(dentry);
		dput(dentry);
		dentry = parent;
		exp = exp_get_by_name(clp, mnt, dentry, reqp);
	}
	dput(dentry);
	return exp;
}

/*
 * Hashtable locking. Write locks are placed only by user processes
 * wanting to modify export information.
 * Write locking only done in this file.  Read locking
 * needed externally.
 */

static DECLARE_RWSEM(hash_sem);

void
exp_readlock(void)
{
	down_read(&hash_sem);
}

static inline void
exp_writelock(void)
{
	down_write(&hash_sem);
}

void
exp_readunlock(void)
{
	up_read(&hash_sem);
}

static inline void
exp_writeunlock(void)
{
	up_write(&hash_sem);
}

static void exp_fsid_unhash(struct svc_export *exp)
{
	struct svc_expkey *ek;

	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return;

	ek = exp_get_fsid_key(exp->ex_client, exp->ex_fsid);
	if (!IS_ERR(ek)) {
		ek->h.expiry_time = get_seconds()-1;
		cache_put(&ek->h, &svc_expkey_cache);
	}
	svc_expkey_cache.nextcheck = get_seconds();
}

static int exp_fsid_hash(svc_client *clp, struct svc_export *exp)
{
	u32 fsid[2];
 
	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return 0;

	mk_fsid(FSID_NUM, fsid, 0, 0, exp->ex_fsid, NULL);
	return exp_set_key(clp, FSID_NUM, fsid, exp);
}

static int exp_hash(struct auth_domain *clp, struct svc_export *exp)
{
	u32 fsid[2];
	struct inode *inode = exp->ex_dentry->d_inode;
	dev_t dev = inode->i_sb->s_dev;

	if (old_valid_dev(dev)) {
		mk_fsid(FSID_DEV, fsid, dev, inode->i_ino, 0, NULL);
		return exp_set_key(clp, FSID_DEV, fsid, exp);
	}
	mk_fsid(FSID_ENCODE_DEV, fsid, dev, inode->i_ino, 0, NULL);
	return exp_set_key(clp, FSID_ENCODE_DEV, fsid, exp);
}

static void exp_unhash(struct svc_export *exp)
{
	struct svc_expkey *ek;
	struct inode *inode = exp->ex_dentry->d_inode;

	ek = exp_get_key(exp->ex_client, inode->i_sb->s_dev, inode->i_ino);
	if (!IS_ERR(ek)) {
		ek->h.expiry_time = get_seconds()-1;
		cache_put(&ek->h, &svc_expkey_cache);
	}
	svc_expkey_cache.nextcheck = get_seconds();
}
	
/*
 * Export a file system.
 */
int
exp_export(struct nfsctl_export *nxp)
{
	svc_client	*clp;
	struct svc_export	*exp = NULL;
	struct svc_export	new;
	struct svc_expkey	*fsid_key = NULL;
	struct nameidata nd;
	int		err;

	/* Consistency check */
	err = -EINVAL;
	if (!exp_verify_string(nxp->ex_path, NFS_MAXPATHLEN) ||
	    !exp_verify_string(nxp->ex_client, NFSCLNT_IDMAX))
		goto out;

	dprintk("exp_export called for %s:%s (%x/%ld fl %x).\n",
			nxp->ex_client, nxp->ex_path,
			(unsigned)nxp->ex_dev, (long)nxp->ex_ino,
			nxp->ex_flags);

	/* Try to lock the export table for update */
	exp_writelock();

	/* Look up client info */
	if (!(clp = auth_domain_find(nxp->ex_client)))
		goto out_unlock;


	/* Look up the dentry */
	err = path_lookup(nxp->ex_path, 0, &nd);
	if (err)
		goto out_unlock;
	err = -EINVAL;

	exp = exp_get_by_name(clp, nd.mnt, nd.dentry, NULL);

	memset(&new, 0, sizeof(new));

	/* must make sure there won't be an ex_fsid clash */
	if ((nxp->ex_flags & NFSEXP_FSID) &&
	    (!IS_ERR(fsid_key = exp_get_fsid_key(clp, nxp->ex_dev))) &&
	    fsid_key->ek_mnt &&
	    (fsid_key->ek_mnt != nd.mnt || fsid_key->ek_dentry != nd.dentry) )
		goto finish;

	if (!IS_ERR(exp)) {
		/* just a flags/id/fsid update */

		exp_fsid_unhash(exp);
		exp->ex_flags    = nxp->ex_flags;
		exp->ex_anon_uid = nxp->ex_anon_uid;
		exp->ex_anon_gid = nxp->ex_anon_gid;
		exp->ex_fsid     = nxp->ex_dev;

		err = exp_fsid_hash(clp, exp);
		goto finish;
	}

	err = check_export(nd.dentry->d_inode, nxp->ex_flags, NULL);
	if (err) goto finish;

	err = -ENOMEM;

	dprintk("nfsd: creating export entry %p for client %p\n", exp, clp);

	new.h.expiry_time = NEVER;
	new.h.flags = 0;
	new.ex_path = kstrdup(nxp->ex_path, GFP_KERNEL);
	if (!new.ex_path)
		goto finish;
	new.ex_client = clp;
	new.ex_mnt = nd.mnt;
	new.ex_dentry = nd.dentry;
	new.ex_flags = nxp->ex_flags;
	new.ex_anon_uid = nxp->ex_anon_uid;
	new.ex_anon_gid = nxp->ex_anon_gid;
	new.ex_fsid = nxp->ex_dev;

	exp = svc_export_lookup(&new);
	if (exp)
		exp = svc_export_update(&new, exp);

	if (!exp)
		goto finish;

	if (exp_hash(clp, exp) ||
	    exp_fsid_hash(clp, exp)) {
		/* failed to create at least one index */
		exp_do_unexport(exp);
		cache_flush();
	} else
		err = 0;
finish:
	if (new.ex_path)
		kfree(new.ex_path);
	if (exp)
		exp_put(exp);
	if (fsid_key && !IS_ERR(fsid_key))
		cache_put(&fsid_key->h, &svc_expkey_cache);
	if (clp)
		auth_domain_put(clp);
	path_release(&nd);
out_unlock:
	exp_writeunlock();
out:
	return err;
}

/*
 * Unexport a file system. The export entry has already
 * been removed from the client's list of exported fs's.
 */
static void
exp_do_unexport(svc_export *unexp)
{
	unexp->h.expiry_time = get_seconds()-1;
	svc_export_cache.nextcheck = get_seconds();
	exp_unhash(unexp);
	exp_fsid_unhash(unexp);
}


/*
 * unexport syscall.