mirror_zfs/module/os/linux/zfs/zpl_export.c
Alyssa Ross f15ec889a9 Return required size when encode_fh size too small
Quoting <linux/exportfs.h>:

> encode_fh() should return the fileid_type on success and on error
> returns 255 (if the space needed to encode fh is greater than
> @max_len*4 bytes). On error @max_len contains the minimum size (in 4
> byte unit) needed to encode the file handle.

ZFS was not setting max_len in the case where the handle was too
small.  As a result of this, the `t_name_to_handle_at.c' example in
name_to_handle_at(2) did not work on ZFS.

zfsctl_fid() will itself set max_len if called with a fid that is too
small, so if we give zfs_fid() that behavior as well, the fix is quite
easy: if the handle is too small, just use a zero-size fid instead of
the handle.

Tested by running t_name_to_handle_at on a normal file, a directory, a
.zfs directory, and a snapshot.

Thanks-to: Puck Meerburg <puck@puckipedia.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Closes #11995
2021-05-10 12:13:45 -07:00

159 lines
3.8 KiB
C

/*
* 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 http://www.opensolaris.org/os/licensing.
* 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/zfs_znode.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_ctldir.h>
#include <sys/zpl.h>
static int
#ifdef HAVE_ENCODE_FH_WITH_INODE
zpl_encode_fh(struct inode *ip, __u32 *fh, int *max_len, struct inode *parent)
{
#else
zpl_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len, int connectable)
{
/* CSTYLED */
struct inode *ip = dentry->d_inode;
#endif /* HAVE_ENCODE_FH_WITH_INODE */
fstrans_cookie_t cookie;
ushort_t empty_fid = 0;
fid_t *fid;
int len_bytes, rc;
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);
spl_fstrans_unmark(cookie);
len_bytes = offsetof(fid_t, fid_data) + fid->fid_len;
*max_len = roundup(len_bytes, sizeof (__u32)) / sizeof (__u32);
return (rc == 0 ? FILEID_INO32_GEN : 255);
}
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 ||
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_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,
.get_parent = zpl_get_parent,
.commit_metadata = zpl_commit_metadata,
};