1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2004-2005 Silicon Graphics, Inc.
4 * All Rights Reserved.
5 */
6 #include "xfs.h"
7 #include "xfs_shared.h"
8 #include "xfs_format.h"
9 #include "xfs_log_format.h"
10 #include "xfs_trans_resv.h"
11 #include "xfs_mount.h"
12 #include "xfs_dir2.h"
13 #include "xfs_export.h"
14 #include "xfs_inode.h"
15 #include "xfs_trans.h"
16 #include "xfs_inode_item.h"
17 #include "xfs_icache.h"
18 #include "xfs_pnfs.h"
19
20 /*
21 * Note that we only accept fileids which are long enough rather than allow
22 * the parent generation number to default to zero. XFS considers zero a
23 * valid generation number not an invalid/wildcard value.
24 */
25 static int xfs_fileid_length(int fileid_type)
26 {
27 switch (fileid_type) {
28 case FILEID_INO32_GEN:
29 return 2;
30 case FILEID_INO32_GEN_PARENT:
31 return 4;
32 case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
33 return 3;
34 case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
35 return 6;
36 }
37 return FILEID_INVALID;
38 }
39
40 STATIC int
41 xfs_fs_encode_fh(
42 struct inode *inode,
43 __u32 *fh,
44 int *max_len,
45 struct inode *parent)
46 {
47 struct xfs_mount *mp = XFS_M(inode->i_sb);
48 struct fid *fid = (struct fid *)fh;
49 struct xfs_fid64 *fid64 = (struct xfs_fid64 *)fh;
50 int fileid_type;
51 int len;
52
53 /* Directories don't need their parent encoded, they have ".." */
54 if (!parent)
55 fileid_type = FILEID_INO32_GEN;
56 else
57 fileid_type = FILEID_INO32_GEN_PARENT;
58
59 /*
60 * If the filesystem may contain 64bit inode numbers, we need
61 * to use larger file handles that can represent them.
62 *
63 * While we only allocate inodes that do not fit into 32 bits any
64 * large enough filesystem may contain them, thus the slightly
65 * confusing looking conditional below.
66 */
67 if (!xfs_has_small_inums(mp) || xfs_is_inode32(mp))
68 fileid_type |= XFS_FILEID_TYPE_64FLAG;
69
70 /*
71 * Only encode if there is enough space given. In practice
72 * this means we can't export a filesystem with 64bit inodes
73 * over NFSv2 with the subtree_check export option; the other
74 * seven combinations work. The real answer is "don't use v2".
75 */
76 len = xfs_fileid_length(fileid_type);
77 if (*max_len < len) {
78 *max_len = len;
79 return FILEID_INVALID;
80 }
81 *max_len = len;
82
83 switch (fileid_type) {
84 case FILEID_INO32_GEN_PARENT:
85 fid->i32.parent_ino = XFS_I(parent)->i_ino;
86 fid->i32.parent_gen = parent->i_generation;
87 fallthrough;
88 case FILEID_INO32_GEN:
89 fid->i32.ino = XFS_I(inode)->i_ino;
90 fid->i32.gen = inode->i_generation;
91 break;
92 case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
93 fid64->parent_ino = XFS_I(parent)->i_ino;
94 fid64->parent_gen = parent->i_generation;
95 fallthrough;
96 case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
97 fid64->ino = XFS_I(inode)->i_ino;
98 fid64->gen = inode->i_generation;
99 break;
100 }
101
102 return fileid_type;
103 }
104
105 struct inode *
106 xfs_nfs_get_inode(
107 struct super_block *sb,
108 u64 ino,
109 u32 generation)
110 {
111 xfs_mount_t *mp = XFS_M(sb);
112 xfs_inode_t *ip;
113 int error;
114
115 /*
116 * NFS can sometimes send requests for ino 0. Fail them gracefully.
117 */
118 if (ino == 0)
119 return ERR_PTR(-ESTALE);
120
121 /*
122 * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
123 * fine and not an indication of a corrupted filesystem as clients can
124 * send invalid file handles and we have to handle it gracefully..
125 */
126 error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
127 if (error) {
128
129 /*
130 * EINVAL means the inode cluster doesn't exist anymore.
131 * EFSCORRUPTED means the metadata pointing to the inode cluster
132 * or the inode cluster itself is corrupt. This implies the
133 * filehandle is stale, so we should translate it here.
134 * We don't use ESTALE directly down the chain to not
135 * confuse applications using bulkstat that expect EINVAL.
136 */
137 switch (error) {
138 case -EINVAL:
139 case -ENOENT:
140 case -EFSCORRUPTED:
141 error = -ESTALE;
142 break;
143 default:
144 break;
145 }
146 return ERR_PTR(error);
147 }
148
149 /*
150 * Reload the incore unlinked list to avoid failure in inodegc.
151 * Use an unlocked check here because unrecovered unlinked inodes
152 * should be somewhat rare.
153 */
154 if (xfs_inode_unlinked_incomplete(ip)) {
155 error = xfs_inode_reload_unlinked(ip);
156 if (error) {
157 xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
158 xfs_irele(ip);
159 return ERR_PTR(error);
160 }
161 }
162
163 if (VFS_I(ip)->i_generation != generation || IS_PRIVATE(VFS_I(ip))) {
164 xfs_irele(ip);
165 return ERR_PTR(-ESTALE);
166 }
167
168 return VFS_I(ip);
169 }
170
171 STATIC struct dentry *
172 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
173 int fh_len, int fileid_type)
174 {
175 struct xfs_fid64 *fid64 = (struct xfs_fid64 *)fid;
176 struct inode *inode = NULL;
177
178 if (fh_len < xfs_fileid_length(fileid_type))
179 return NULL;
180
181 switch (fileid_type) {
182 case FILEID_INO32_GEN_PARENT:
183 case FILEID_INO32_GEN:
184 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
185 break;
186 case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
187 case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
188 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
189 break;
190 }
191
192 return d_obtain_alias(inode);
193 }
194
195 STATIC struct dentry *
196 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
197 int fh_len, int fileid_type)
198 {
199 struct xfs_fid64 *fid64 = (struct xfs_fid64 *)fid;
200 struct inode *inode = NULL;
201
202 if (fh_len < xfs_fileid_length(fileid_type))
203 return NULL;
204
205 switch (fileid_type) {
206 case FILEID_INO32_GEN_PARENT:
207 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
208 fid->i32.parent_gen);
209 break;
210 case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
211 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
212 fid64->parent_gen);
213 break;
214 }
215
216 return d_obtain_alias(inode);
217 }
218
219 STATIC struct dentry *
220 xfs_fs_get_parent(
221 struct dentry *child)
222 {
223 int error;
224 struct xfs_inode *cip;
225
226 error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
227 if (unlikely(error))
228 return ERR_PTR(error);
229
230 return d_obtain_alias(VFS_I(cip));
231 }
232
233 STATIC int
234 xfs_fs_nfs_commit_metadata(
235 struct inode *inode)
236 {
237 return xfs_log_force_inode(XFS_I(inode));
238 }
239
240 const struct export_operations xfs_export_operations = {
241 .encode_fh = xfs_fs_encode_fh,
242 .fh_to_dentry = xfs_fs_fh_to_dentry,
243 .fh_to_parent = xfs_fs_fh_to_parent,
244 .get_parent = xfs_fs_get_parent,
245 .commit_metadata = xfs_fs_nfs_commit_metadata,
246 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
247 .get_uuid = xfs_fs_get_uuid,
248 .map_blocks = xfs_fs_map_blocks,
249 .commit_blocks = xfs_fs_commit_blocks,
250 #endif
251 };
252
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