mirror_zfs/module/os/linux/zfs/zpl_export.c

// SPDX-License-Identifier: CDDL-1.0
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or https://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2011 Gunnar Beutner
 * Copyright (c) 2012 Cyril Plisko. All rights reserved.
 */


#include <sys/file.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_ctldir.h>
#include <sys/zpl.h>


static int
zpl_encode_fh(struct inode *ip, __u32 *fh, int *max_len, struct inode *parent)
{
	fstrans_cookie_t cookie;
	ushort_t empty_fid = 0;
	fid_t *fid, *pfid;
	int len_bytes, required_len, parent_len, rc, prc, fh_type;

	len_bytes = *max_len * sizeof (__u32);

	if (len_bytes < offsetof(fid_t, fid_data)) {
		fid = (fid_t *)&empty_fid;
	} else {
		fid = (fid_t *)fh;
		fid->fid_len = len_bytes - offsetof(fid_t, fid_data);
	}

	cookie = spl_fstrans_mark();

	if (zfsctl_is_node(ip))
		rc = zfsctl_fid(ip, fid);
	else
		rc = zfs_fid(ip, fid);

	required_len = offsetof(fid_t, fid_data) + fid->fid_len;

	/*
	 * Kernel has requested that the resulting file handle contain
	 * a reference to the provided parent. This typically would happen
	 * if the NFS export has subtree checking enabled.
	 */
	if (parent != NULL) {
		if ((rc == 0) && (len_bytes >
		    required_len + offsetof(fid_t, fid_data))) {
			parent_len = len_bytes - required_len;
			pfid = (fid_t *)((char *)fh + required_len);
			pfid->fid_len = parent_len - offsetof(fid_t, fid_data);
		} else {
			empty_fid = 0;
			pfid = (fid_t *)&empty_fid;
		}

		if (zfsctl_is_node(parent))
			prc = zfsctl_fid(parent, pfid);
		else
			prc = zfs_fid(parent, pfid);

		if (rc == 0 && prc != 0)
			rc = prc;

		required_len += offsetof(fid_t, fid_data) +
		    pfid->fid_len;
		fh_type = FILEID_INO32_GEN_PARENT;
	} else {
		fh_type = FILEID_INO32_GEN;
	}

	spl_fstrans_unmark(cookie);

	*max_len = roundup(required_len, sizeof (__u32)) / sizeof (__u32);

	return (rc == 0 ? fh_type : FILEID_INVALID);
}

static struct dentry *
zpl_fh_to_dentry(struct super_block *sb, struct fid *fh,
    int fh_len, int fh_type)
{
	fid_t *fid = (fid_t *)fh;
	fstrans_cookie_t cookie;
	struct inode *ip;
	int len_bytes, rc;

	len_bytes = fh_len * sizeof (__u32);

	if ((fh_type != FILEID_INO32_GEN &&
	    fh_type != FILEID_INO32_GEN_PARENT) ||
	    len_bytes < offsetof(fid_t, fid_data) ||
	    len_bytes < offsetof(fid_t, fid_data) + fid->fid_len)
		return (ERR_PTR(-EINVAL));

	cookie = spl_fstrans_mark();
	rc = zfs_vget(sb, &ip, fid);
	spl_fstrans_unmark(cookie);

	if (rc) {
		/*
		 * If we see ENOENT it might mean that an NFSv4 * client
		 * is using a cached inode value in a file handle and
		 * that the sought after file has had its inode changed
		 * by a third party.  So change the error to ESTALE
		 * which will trigger a full lookup by the client and
		 * will find the new filename/inode pair if it still
		 * exists.
		 */
		if (rc == ENOENT)
			rc = ESTALE;

		return (ERR_PTR(-rc));
	}

	ASSERT((ip != NULL) && !IS_ERR(ip));

	return (d_obtain_alias(ip));
}

static struct dentry *
zpl_fh_to_parent(struct super_block *sb, struct fid *fh,
    int fh_len, int fh_type)
{
	/*
	 * Convert the provided struct fid to a dentry for the parent
	 * This is possible only if it was created with the parent,
	 * e.g. type is FILEID_INO32_GEN_PARENT. When this type of
	 * filehandle is created we simply pack the parent fid_t
	 * after the entry's fid_t. So this function will adjust
	 * offset in the provided buffer to the begining of the
	 * parent fid_t and call zpl_fh_to_dentry() on it.
	 */
	fid_t *fid = (fid_t *)fh;
	fid_t *pfid;
	int len_bytes, parent_len_bytes, child_fid_bytes, parent_fh_len;

	len_bytes = fh_len * sizeof (__u32);

	if ((fh_type != FILEID_INO32_GEN_PARENT) ||
	    len_bytes < offsetof(fid_t, fid_data) ||
	    len_bytes < offsetof(fid_t, fid_data) + fid->fid_len)
		return (ERR_PTR(-EINVAL));

	child_fid_bytes = offsetof(fid_t, fid_data) + fid->fid_len;
	parent_len_bytes = len_bytes - child_fid_bytes;

	if (parent_len_bytes < offsetof(fid_t, fid_data))
		return (ERR_PTR(-EINVAL));

	pfid = (fid_t *)((char *)fh + child_fid_bytes);

	if (parent_len_bytes < offsetof(fid_t, fid_data) + pfid->fid_len)
		return (ERR_PTR(-EINVAL));

	parent_fh_len = parent_len_bytes / sizeof (__u32);
	return (zpl_fh_to_dentry(sb, (struct fid *)pfid, parent_fh_len,
	    FILEID_INO32_GEN));
}

/*
 * In case the filesystem contains name longer than 255, we need to override
 * the default get_name so we don't get buffer overflow. Unfortunately, since
 * the buffer size is hardcoded in Linux, we will get ESTALE error in this
 * case.
 */
static int
zpl_get_name(struct dentry *parent, char *name, struct dentry *child)
{
	cred_t *cr = CRED();
	fstrans_cookie_t cookie;
	struct inode *dir = parent->d_inode;
	struct inode *ip = child->d_inode;
	int error;

	if (!dir || !S_ISDIR(dir->i_mode))
		return (-ENOTDIR);

	crhold(cr);
	cookie = spl_fstrans_mark();
	spl_inode_lock_shared(dir);
	error = -zfs_get_name(ITOZ(dir), name, ITOZ(ip));
	spl_inode_unlock_shared(dir);
	spl_fstrans_unmark(cookie);
	crfree(cr);

	return (error);
}

static struct dentry *
zpl_get_parent(struct dentry *child)
{
	cred_t *cr = CRED();
	fstrans_cookie_t cookie;
	znode_t *zp;
	int error;

	crhold(cr);
	cookie = spl_fstrans_mark();
	error = -zfs_lookup(ITOZ(child->d_inode), "..", &zp, 0, cr, NULL, NULL);
	spl_fstrans_unmark(cookie);
	crfree(cr);
	ASSERT3S(error, <=, 0);

	if (error)
		return (ERR_PTR(error));

	return (d_obtain_alias(ZTOI(zp)));
}

static int
zpl_commit_metadata(struct inode *inode)
{
	cred_t *cr = CRED();
	fstrans_cookie_t cookie;
	int error;

	if (zfsctl_is_node(inode))
		return (0);

	crhold(cr);
	cookie = spl_fstrans_mark();
	error = -zfs_fsync(ITOZ(inode), 0, cr);
	spl_fstrans_unmark(cookie);
	crfree(cr);
	ASSERT3S(error, <=, 0);

	return (error);
}

const struct export_operations zpl_export_operations = {
	.encode_fh		= zpl_encode_fh,
	.fh_to_dentry		= zpl_fh_to_dentry,
	.fh_to_parent		= zpl_fh_to_parent,
	.get_name		= zpl_get_name,
	.get_parent		= zpl_get_parent,
	.commit_metadata	= zpl_commit_metadata,
};