GNU Linux-libre 5.19-rc6-gnu
[releases.git] / fs / xfs / xfs_export.c
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 STATIC 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         if (VFS_I(ip)->i_generation != generation) {
150                 xfs_irele(ip);
151                 return ERR_PTR(-ESTALE);
152         }
153
154         return VFS_I(ip);
155 }
156
157 STATIC struct dentry *
158 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
159                  int fh_len, int fileid_type)
160 {
161         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
162         struct inode            *inode = NULL;
163
164         if (fh_len < xfs_fileid_length(fileid_type))
165                 return NULL;
166
167         switch (fileid_type) {
168         case FILEID_INO32_GEN_PARENT:
169         case FILEID_INO32_GEN:
170                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
171                 break;
172         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
173         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
174                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
175                 break;
176         }
177
178         return d_obtain_alias(inode);
179 }
180
181 STATIC struct dentry *
182 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
183                  int fh_len, int fileid_type)
184 {
185         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
186         struct inode            *inode = NULL;
187
188         if (fh_len < xfs_fileid_length(fileid_type))
189                 return NULL;
190
191         switch (fileid_type) {
192         case FILEID_INO32_GEN_PARENT:
193                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
194                                               fid->i32.parent_gen);
195                 break;
196         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
197                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
198                                               fid64->parent_gen);
199                 break;
200         }
201
202         return d_obtain_alias(inode);
203 }
204
205 STATIC struct dentry *
206 xfs_fs_get_parent(
207         struct dentry           *child)
208 {
209         int                     error;
210         struct xfs_inode        *cip;
211
212         error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
213         if (unlikely(error))
214                 return ERR_PTR(error);
215
216         return d_obtain_alias(VFS_I(cip));
217 }
218
219 STATIC int
220 xfs_fs_nfs_commit_metadata(
221         struct inode            *inode)
222 {
223         return xfs_log_force_inode(XFS_I(inode));
224 }
225
226 const struct export_operations xfs_export_operations = {
227         .encode_fh              = xfs_fs_encode_fh,
228         .fh_to_dentry           = xfs_fs_fh_to_dentry,
229         .fh_to_parent           = xfs_fs_fh_to_parent,
230         .get_parent             = xfs_fs_get_parent,
231         .commit_metadata        = xfs_fs_nfs_commit_metadata,
232 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
233         .get_uuid               = xfs_fs_get_uuid,
234         .map_blocks             = xfs_fs_map_blocks,
235         .commit_blocks          = xfs_fs_commit_blocks,
236 #endif
237 };