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
afs_silly_rename_success(struct afs_operation * op)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
afs_silly_rename_edit_dir(struct afs_operation * op)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 */
afs_do_silly_rename(struct afs_vnode * dvnode,struct afs_vnode * vnode,struct dentry * old,struct dentry * new,struct key * key)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 */
afs_sillyrename(struct afs_vnode * dvnode,struct afs_vnode * vnode,struct dentry * dentry,struct key * key)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 dput(sdentry);
117 sillycounter++;
118
119 /* Create a silly name. Note that the ".__afs" prefix is
120 * understood by the salvager and must not be changed.
121 */
122 scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
123 sdentry = lookup_noperm(&QSTR(silly), dentry->d_parent);
124
125 /* N.B. Better to return EBUSY here ... it could be dangerous
126 * to delete the file while it's in use.
127 */
128 if (IS_ERR(sdentry))
129 goto out;
130 } while (!d_is_negative(sdentry));
131
132 ihold(&vnode->netfs.inode);
133
134 ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
135 switch (ret) {
136 case 0:
137 /* The rename succeeded. */
138 set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
139 d_move(dentry, sdentry);
140 break;
141 case -ERESTARTSYS:
142 /* The result of the rename is unknown. Play it safe by forcing
143 * a new lookup.
144 */
145 d_drop(dentry);
146 d_drop(sdentry);
147 }
148
149 iput(&vnode->netfs.inode);
150 dput(sdentry);
151 out:
152 _leave(" = %d", ret);
153 return ret;
154 }
155
afs_silly_unlink_success(struct afs_operation * op)156 static void afs_silly_unlink_success(struct afs_operation *op)
157 {
158 _enter("op=%08x", op->debug_id);
159 afs_check_dir_conflict(op, &op->file[0]);
160 afs_vnode_commit_status(op, &op->file[0]);
161 afs_vnode_commit_status(op, &op->file[1]);
162 afs_update_dentry_version(op, &op->file[0], op->dentry);
163 }
164
afs_silly_unlink_edit_dir(struct afs_operation * op)165 static void afs_silly_unlink_edit_dir(struct afs_operation *op)
166 {
167 struct afs_vnode_param *dvp = &op->file[0];
168 struct afs_vnode *dvnode = dvp->vnode;
169
170 _enter("op=%08x", op->debug_id);
171 down_write(&dvnode->validate_lock);
172 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
173 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
174 afs_edit_dir_remove(dvnode, &op->dentry->d_name,
175 afs_edit_dir_for_unlink);
176 up_write(&dvnode->validate_lock);
177 }
178
179 static const struct afs_operation_ops afs_silly_unlink_operation = {
180 .issue_afs_rpc = afs_fs_remove_file,
181 .issue_yfs_rpc = yfs_fs_remove_file,
182 .success = afs_silly_unlink_success,
183 .aborted = afs_check_for_remote_deletion,
184 .edit_dir = afs_silly_unlink_edit_dir,
185 };
186
187 /*
188 * Tell the server to remove a sillyrename file.
189 */
afs_do_silly_unlink(struct afs_vnode * dvnode,struct afs_vnode * vnode,struct dentry * dentry,struct key * key)190 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
191 struct dentry *dentry, struct key *key)
192 {
193 struct afs_operation *op;
194
195 _enter("");
196
197 op = afs_alloc_operation(NULL, dvnode->volume);
198 if (IS_ERR(op))
199 return PTR_ERR(op);
200
201 afs_op_set_vnode(op, 0, dvnode);
202 afs_op_set_vnode(op, 1, vnode);
203 op->file[0].dv_delta = 1;
204 op->file[0].modification = true;
205 op->file[0].update_ctime = true;
206 op->file[1].op_unlinked = true;
207 op->file[1].update_ctime = true;
208
209 op->dentry = dentry;
210 op->ops = &afs_silly_unlink_operation;
211
212 trace_afs_silly_rename(vnode, true);
213 afs_begin_vnode_operation(op);
214 afs_wait_for_operation(op);
215
216 /* If there was a conflict with a third party, check the status of the
217 * unlinked vnode.
218 */
219 if (op->cumul_error.error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
220 op->file[1].update_ctime = false;
221 op->fetch_status.which = 1;
222 op->ops = &afs_fetch_status_operation;
223 afs_begin_vnode_operation(op);
224 afs_wait_for_operation(op);
225 }
226
227 return afs_put_operation(op);
228 }
229
230 /*
231 * Remove sillyrename file on iput.
232 */
afs_silly_iput(struct dentry * dentry,struct inode * inode)233 int afs_silly_iput(struct dentry *dentry, struct inode *inode)
234 {
235 struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
236 struct afs_vnode *vnode = AFS_FS_I(inode);
237 struct dentry *alias;
238 int ret;
239
240 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
241
242 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
243
244 down_read(&dvnode->rmdir_lock);
245
246 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
247 if (IS_ERR(alias)) {
248 up_read(&dvnode->rmdir_lock);
249 return 0;
250 }
251
252 if (!d_in_lookup(alias)) {
253 /* We raced with lookup... See if we need to transfer the
254 * sillyrename information to the aliased dentry.
255 */
256 ret = 0;
257 spin_lock(&alias->d_lock);
258 if (d_really_is_positive(alias) &&
259 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
260 alias->d_flags |= DCACHE_NFSFS_RENAMED;
261 ret = 1;
262 }
263 spin_unlock(&alias->d_lock);
264 up_read(&dvnode->rmdir_lock);
265 dput(alias);
266 return ret;
267 }
268
269 /* Stop lock-release from complaining. */
270 spin_lock(&vnode->lock);
271 vnode->lock_state = AFS_VNODE_LOCK_DELETED;
272 trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
273 spin_unlock(&vnode->lock);
274
275 afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
276 up_read(&dvnode->rmdir_lock);
277 d_lookup_done(alias);
278 dput(alias);
279 return 1;
280 }
281