1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2015, Primary Data, Inc. All rights reserved.
4 *
5 * Tao Peng <bergwolf@primarydata.com>
6 */
7#include <linux/dcache.h>
8#include <linux/exportfs.h>
9#include <linux/nfs.h>
10#include <linux/nfs_fs.h>
11
12#include "internal.h"
13#include "nfstrace.h"
14
15#define NFSDBG_FACILITY		NFSDBG_VFS
16
17enum {
18	FILEID_HIGH_OFF = 0,	/* inode fileid high */
19	FILEID_LOW_OFF,		/* inode fileid low */
20	FILE_I_TYPE_OFF,	/* inode type */
21	EMBED_FH_OFF		/* embeded server fh */
22};
23
24
25static struct nfs_fh *nfs_exp_embedfh(__u32 *p)
26{
27	return (struct nfs_fh *)(p + EMBED_FH_OFF);
28}
29
30/*
31 * Let's break subtree checking for now... otherwise we'll have to embed parent fh
32 * but there might not be enough space.
33 */
34static int
35nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent)
36{
37	struct nfs_fh *server_fh = NFS_FH(inode);
38	struct nfs_fh *clnt_fh = nfs_exp_embedfh(p);
39	size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
40	int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
41
42	dprintk("%s: max fh len %d inode %p parent %p",
43		__func__, *max_len, inode, parent);
44
45	if (*max_len < len) {
46		dprintk("%s: fh len %d too small, required %d\n",
47			__func__, *max_len, len);
48		*max_len = len;
49		return FILEID_INVALID;
50	}
51
52	p[FILEID_HIGH_OFF] = NFS_FILEID(inode) >> 32;
53	p[FILEID_LOW_OFF] = NFS_FILEID(inode);
54	p[FILE_I_TYPE_OFF] = inode->i_mode & S_IFMT;
55	p[len - 1] = 0; /* Padding */
56	nfs_copy_fh(clnt_fh, server_fh);
57	*max_len = len;
58	dprintk("%s: result fh fileid %llu mode %u size %d\n",
59		__func__, NFS_FILEID(inode), inode->i_mode, *max_len);
60	return *max_len;
61}
62
63static struct dentry *
64nfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
65		 int fh_len, int fh_type)
66{
67	struct nfs_fattr *fattr = NULL;
68	struct nfs_fh *server_fh = nfs_exp_embedfh(fid->raw);
69	size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
70	const struct nfs_rpc_ops *rpc_ops;
71	struct dentry *dentry;
72	struct inode *inode;
73	int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
74	u32 *p = fid->raw;
75	int ret;
76
77	/* NULL translates to ESTALE */
78	if (fh_len < len || fh_type != len)
79		return NULL;
80
81	fattr = nfs_alloc_fattr_with_label(NFS_SB(sb));
82	if (fattr == NULL) {
83		dentry = ERR_PTR(-ENOMEM);
84		goto out;
85	}
86
87	fattr->fileid = ((u64)p[FILEID_HIGH_OFF] << 32) + p[FILEID_LOW_OFF];
88	fattr->mode = p[FILE_I_TYPE_OFF];
89	fattr->valid |= NFS_ATTR_FATTR_FILEID | NFS_ATTR_FATTR_TYPE;
90
91	dprintk("%s: fileid %llu mode %d\n", __func__, fattr->fileid, fattr->mode);
92
93	inode = nfs_ilookup(sb, fattr, server_fh);
94	if (inode)
95		goto out_found;
96
97	rpc_ops = NFS_SB(sb)->nfs_client->rpc_ops;
98	ret = rpc_ops->getattr(NFS_SB(sb), server_fh, fattr, NULL);
99	if (ret) {
100		dprintk("%s: getattr failed %d\n", __func__, ret);
101		trace_nfs_fh_to_dentry(sb, server_fh, fattr->fileid, ret);
102		dentry = ERR_PTR(ret);
103		goto out_free_fattr;
104	}
105
106	inode = nfs_fhget(sb, server_fh, fattr);
107
108out_found:
109	dentry = d_obtain_alias(inode);
110out_free_fattr:
111	nfs_free_fattr(fattr);
112out:
113	return dentry;
114}
115
116static struct dentry *
117nfs_get_parent(struct dentry *dentry)
118{
119	int ret;
120	struct inode *inode = d_inode(dentry), *pinode;
121	struct super_block *sb = inode->i_sb;
122	struct nfs_server *server = NFS_SB(sb);
123	struct nfs_fattr *fattr = NULL;
124	struct dentry *parent;
125	struct nfs_rpc_ops const *ops = server->nfs_client->rpc_ops;
126	struct nfs_fh fh;
127
128	if (!ops->lookupp)
129		return ERR_PTR(-EACCES);
130
131	fattr = nfs_alloc_fattr_with_label(server);
132	if (fattr == NULL)
133		return ERR_PTR(-ENOMEM);
134
135	ret = ops->lookupp(inode, &fh, fattr);
136	if (ret) {
137		parent = ERR_PTR(ret);
138		goto out;
139	}
140
141	pinode = nfs_fhget(sb, &fh, fattr);
142	parent = d_obtain_alias(pinode);
143out:
144	nfs_free_fattr(fattr);
145	return parent;
146}
147
148const struct export_operations nfs_export_ops = {
149	.encode_fh = nfs_encode_fh,
150	.fh_to_dentry = nfs_fh_to_dentry,
151	.get_parent = nfs_get_parent,
152	.flags = EXPORT_OP_NOWCC		|
153		 EXPORT_OP_NOSUBTREECHK		|
154		 EXPORT_OP_CLOSE_BEFORE_UNLINK	|
155		 EXPORT_OP_REMOTE_FS		|
156		 EXPORT_OP_NOATOMIC_ATTR	|
157		 EXPORT_OP_FLUSH_ON_CLOSE,
158};
159