export.c

  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);
 70	const struct nfs_rpc_ops *rpc_ops;
 71	struct dentry *dentry;
 72	struct inode *inode;
 73	int len = EMBED_FH_OFF;
 74	u32 *p = fid->raw;
 75	int ret;
 76
 77	/* Initial check of bounds */
 78	if (fh_len < len + XDR_QUADLEN(fh_size) ||
 79	    fh_len > XDR_QUADLEN(NFS_MAXFHSIZE))
 80		return NULL;
 81	/* Calculate embedded filehandle size */
 82	fh_size += server_fh->size;
 83	len += XDR_QUADLEN(fh_size);
 84	/* NULL translates to ESTALE */
 85	if (fh_len < len || fh_type != len)
 86		return NULL;
 87
 88	fattr = nfs_alloc_fattr_with_label(NFS_SB(sb));
 89	if (fattr == NULL) {
 90		dentry = ERR_PTR(-ENOMEM);
 91		goto out;
 92	}
 93
 94	fattr->fileid = ((u64)p[FILEID_HIGH_OFF] << 32) + p[FILEID_LOW_OFF];
 95	fattr->mode = p[FILE_I_TYPE_OFF];
 96	fattr->valid |= NFS_ATTR_FATTR_FILEID | NFS_ATTR_FATTR_TYPE;
 97
 98	dprintk("%s: fileid %llu mode %d\n", __func__, fattr->fileid, fattr->mode);
 99
100	inode = nfs_ilookup(sb, fattr, server_fh);
101	if (inode)
102		goto out_found;
103
104	rpc_ops = NFS_SB(sb)->nfs_client->rpc_ops;
105	ret = rpc_ops->getattr(NFS_SB(sb), server_fh, fattr, NULL);
106	if (ret) {
107		dprintk("%s: getattr failed %d\n", __func__, ret);
108		trace_nfs_fh_to_dentry(sb, server_fh, fattr->fileid, ret);
109		dentry = ERR_PTR(ret);
110		goto out_free_fattr;
111	}
112
113	inode = nfs_fhget(sb, server_fh, fattr);
114
115out_found:
116	dentry = d_obtain_alias(inode);
117out_free_fattr:
118	nfs_free_fattr(fattr);
119out:
120	return dentry;
121}
122
123static struct dentry *
124nfs_get_parent(struct dentry *dentry)
125{
126	int ret;
127	struct inode *inode = d_inode(dentry), *pinode;
128	struct super_block *sb = inode->i_sb;
129	struct nfs_server *server = NFS_SB(sb);
130	struct nfs_fattr *fattr = NULL;
131	struct dentry *parent;
132	struct nfs_rpc_ops const *ops = server->nfs_client->rpc_ops;
133	struct nfs_fh fh;
134
135	if (!ops->lookupp)
136		return ERR_PTR(-EACCES);
137
138	fattr = nfs_alloc_fattr_with_label(server);
139	if (fattr == NULL)
140		return ERR_PTR(-ENOMEM);
141
142	ret = ops->lookupp(inode, &fh, fattr);
143	if (ret) {
144		parent = ERR_PTR(ret);
145		goto out;
146	}
147
148	pinode = nfs_fhget(sb, &fh, fattr);
149	parent = d_obtain_alias(pinode);
150out:
151	nfs_free_fattr(fattr);
152	return parent;
153}
154
155const struct export_operations nfs_export_ops = {
156	.encode_fh = nfs_encode_fh,
157	.fh_to_dentry = nfs_fh_to_dentry,
158	.get_parent = nfs_get_parent,
159	.flags = EXPORT_OP_NOWCC		|
160		 EXPORT_OP_NOSUBTREECHK		|
161		 EXPORT_OP_CLOSE_BEFORE_UNLINK	|
162		 EXPORT_OP_REMOTE_FS		|
163		 EXPORT_OP_NOATOMIC_ATTR	|
164		 EXPORT_OP_FLUSH_ON_CLOSE	|
165		 EXPORT_OP_NOLOCKS,
166};