1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS silly rename handling
3 *
4 * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 * - Derived from NFS's sillyrename.
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/fs.h>
11 #include <linux/namei.h>
12 #include <linux/fsnotify.h>
13 #include "internal.h"
14
15 static void afs_silly_rename_success(struct afs_operation *op)
16 {
17 _enter("op=%08x", op->debug_id);
18
19 afs_check_dir_conflict(op, &op->file[0]);
20 afs_vnode_commit_status(op, &op->file[0]);
21 }
22
23 static void afs_silly_rename_edit_dir(struct afs_operation *op)
24 {
25 struct afs_vnode_param *dvp = &op->file[0];
26 struct afs_vnode *dvnode = dvp->vnode;
27 struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
28 struct dentry *old = op->dentry;
29 struct dentry *new = op->dentry_2;
30
31 spin_lock(&old->d_lock);
32 old->d_flags |= DCACHE_NFSFS_RENAMED;
33 spin_unlock(&old->d_lock);
34 if (dvnode->silly_key != op->key) {
35 key_put(dvnode->silly_key);
36 dvnode->silly_key = key_get(op->key);
37 }
38
39 down_write(&dvnode->validate_lock);
40 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
41 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) {
42 afs_edit_dir_remove(dvnode, &old->d_name,
43 afs_edit_dir_for_silly_0);
44 afs_edit_dir_add(dvnode, &new->d_name,
45 &vnode->fid, afs_edit_dir_for_silly_1);
46 }
47 up_write(&dvnode->validate_lock);
48 }
49
50 static const struct afs_operation_ops afs_silly_rename_operation = {
51 .issue_afs_rpc = afs_fs_rename,
52 .issue_yfs_rpc = yfs_fs_rename,
53 .success = afs_silly_rename_success,
54 .edit_dir = afs_silly_rename_edit_dir,
55 };
56
57 /*
58 * Actually perform the silly rename step.
59 */
60 static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
61 struct dentry *old, struct dentry *new,
62 struct key *key)
63 {
64 struct afs_operation *op;
65
66 _enter("%pd,%pd", old, new);
67
68 op = afs_alloc_operation(key, dvnode->volume);
69 if (IS_ERR(op))
70 return PTR_ERR(op);
71
72 afs_op_set_vnode(op, 0, dvnode);
73 afs_op_set_vnode(op, 1, dvnode);
74 op->file[0].dv_delta = 1;
75 op->file[1].dv_delta = 1;
76 op->file[0].modification = true;
77 op->file[1].modification = true;
78 op->file[0].update_ctime = true;
79 op->file[1].update_ctime = true;
80
81 op->dentry = old;
82 op->dentry_2 = new;
83 op->ops = &afs_silly_rename_operation;
84
85 trace_afs_silly_rename(vnode, false);
86 return afs_do_sync_operation(op);
87 }
88
89 /*
90 * Perform silly-rename of a dentry.
91 *
92 * AFS is stateless and the server doesn't know when the client is holding a
93 * file open. To prevent application problems when a file is unlinked while
94 * it's still open, the client performs a "silly-rename". That is, it renames
95 * the file to a hidden file in the same directory, and only performs the
96 * unlink once the last reference to it is put.
97 *
98 * The final cleanup is done during dentry_iput.
99 */
100 int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
101 struct dentry *dentry, struct key *key)
102 {
103 static unsigned int sillycounter;
104 struct dentry *sdentry = NULL;
105 unsigned char silly[16];
106 int ret = -EBUSY;
107
108 _enter("");
109
110 /* We don't allow a dentry to be silly-renamed twice. */
111 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
112 return -EBUSY;
113
114 sdentry = NULL;
115 do {
116 int slen;
117
118 dput(sdentry);
119 sillycounter++;
120
121 /* Create a silly name. Note that the ".__afs" prefix is
122 * understood by the salvager and must not be changed.
123 */
124 slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
125 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
126
127 /* N.B. Better to return EBUSY here ... it could be dangerous
128 * to delete the file while it's in use.
129 */
130 if (IS_ERR(sdentry))
131 goto out;
132 } while (!d_is_negative(sdentry));
133
134 ihold(&vnode->netfs.inode);
135
136 ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
137 switch (ret) {
138 case 0:
139 /* The rename succeeded. */
140 set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
141 d_move(dentry, sdentry);
142 break;
143 case -ERESTARTSYS:
144 /* The result of the rename is unknown. Play it safe by forcing
145 * a new lookup.
146 */
147 d_drop(dentry);
148 d_drop(sdentry);
149 }
150
151 iput(&vnode->netfs.inode);
152 dput(sdentry);
153 out:
154 _leave(" = %d", ret);
155 return ret;
156 }
157
158 static void afs_silly_unlink_success(struct afs_operation *op)
159 {
160 _enter("op=%08x", op->debug_id);
161 afs_check_dir_conflict(op, &op->file[0]);
162 afs_vnode_commit_status(op, &op->file[0]);
163 afs_vnode_commit_status(op, &op->file[1]);
164 afs_update_dentry_version(op, &op->file[0], op->dentry);
165 }
166
167 static void afs_silly_unlink_edit_dir(struct afs_operation *op)
168 {
169 struct afs_vnode_param *dvp = &op->file[0];
170 struct afs_vnode *dvnode = dvp->vnode;
171
172 _enter("op=%08x", op->debug_id);
173 down_write(&dvnode->validate_lock);
174 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
175 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
176 afs_edit_dir_remove(dvnode, &op->dentry->d_name,
177 afs_edit_dir_for_unlink);
178 up_write(&dvnode->validate_lock);
179 }
180
181 static const struct afs_operation_ops afs_silly_unlink_operation = {
182 .issue_afs_rpc = afs_fs_remove_file,
183 .issue_yfs_rpc = yfs_fs_remove_file,
184 .success = afs_silly_unlink_success,
185 .aborted = afs_check_for_remote_deletion,
186 .edit_dir = afs_silly_unlink_edit_dir,
187 };
188
189 /*
190 * Tell the server to remove a sillyrename file.
191 */
192 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
193 struct dentry *dentry, struct key *key)
194 {
195 struct afs_operation *op;
196
197 _enter("");
198
199 op = afs_alloc_operation(NULL, dvnode->volume);
200 if (IS_ERR(op))
201 return PTR_ERR(op);
202
203 afs_op_set_vnode(op, 0, dvnode);
204 afs_op_set_vnode(op, 1, vnode);
205 op->file[0].dv_delta = 1;
206 op->file[0].modification = true;
207 op->file[0].update_ctime = true;
208 op->file[1].op_unlinked = true;
209 op->file[1].update_ctime = true;
210
211 op->dentry = dentry;
212 op->ops = &afs_silly_unlink_operation;
213
214 trace_afs_silly_rename(vnode, true);
215 afs_begin_vnode_operation(op);
216 afs_wait_for_operation(op);
217
218 /* If there was a conflict with a third party, check the status of the
219 * unlinked vnode.
220 */
221 if (op->cumul_error.error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
222 op->file[1].update_ctime = false;
223 op->fetch_status.which = 1;
224 op->ops = &afs_fetch_status_operation;
225 afs_begin_vnode_operation(op);
226 afs_wait_for_operation(op);
227 }
228
229 return afs_put_operation(op);
230 }
231
232 /*
233 * Remove sillyrename file on iput.
234 */
235 int afs_silly_iput(struct dentry *dentry, struct inode *inode)
236 {
237 struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
238 struct afs_vnode *vnode = AFS_FS_I(inode);
239 struct dentry *alias;
240 int ret;
241
242 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
243
244 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
245
246 down_read(&dvnode->rmdir_lock);
247
248 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
249 if (IS_ERR(alias)) {
250 up_read(&dvnode->rmdir_lock);
251 return 0;
252 }
253
254 if (!d_in_lookup(alias)) {
255 /* We raced with lookup... See if we need to transfer the
256 * sillyrename information to the aliased dentry.
257 */
258 ret = 0;
259 spin_lock(&alias->d_lock);
260 if (d_really_is_positive(alias) &&
261 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
262 alias->d_flags |= DCACHE_NFSFS_RENAMED;
263 ret = 1;
264 }
265 spin_unlock(&alias->d_lock);
266 up_read(&dvnode->rmdir_lock);
267 dput(alias);
268 return ret;
269 }
270
271 /* Stop lock-release from complaining. */
272 spin_lock(&vnode->lock);
273 vnode->lock_state = AFS_VNODE_LOCK_DELETED;
274 trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
275 spin_unlock(&vnode->lock);
276
277 afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
278 up_read(&dvnode->rmdir_lock);
279 d_lookup_done(alias);
280 dput(alias);
281 return 1;
282 }
283
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