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
15static void afs_silly_rename_success(struct afs_operation *op)
16{
17 _enter("op=%08x", op->debug_id);
18
19 afs_check_dir_conflict(op, dvp: &op->file[0]);
20 afs_vnode_commit_status(op, &op->file[0]);
21}
22
23static 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(inode: d_inode(dentry: op->dentry));
28 struct dentry *old = op->dentry;
29 struct dentry *new = op->dentry_2;
30
31 spin_lock(lock: &old->d_lock);
32 old->d_flags |= DCACHE_NFSFS_RENAMED;
33 spin_unlock(lock: &old->d_lock);
34 if (dvnode->silly_key != op->key) {
35 key_put(key: dvnode->silly_key);
36 dvnode->silly_key = key_get(key: op->key);
37 }
38
39 down_write(sem: &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(sem: &dvnode->validate_lock);
48}
49
50static 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 */
60static 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(ptr: op))
70 return PTR_ERR(ptr: op);
71
72 op->more_files = kvcalloc(2, sizeof(struct afs_vnode_param), GFP_KERNEL);
73 if (!op->more_files) {
74 afs_put_operation(op);
75 return -ENOMEM;
76 }
77
78 afs_op_set_vnode(op, n: 0, vnode: dvnode);
79 afs_op_set_vnode(op, n: 1, vnode: dvnode);
80 op->file[0].dv_delta = 1;
81 op->file[1].dv_delta = 1;
82 op->file[0].modification = true;
83 op->file[1].modification = true;
84 op->file[0].update_ctime = true;
85 op->file[1].update_ctime = true;
86 op->more_files[0].vnode = AFS_FS_I(inode: d_inode(dentry: old));
87 op->more_files[0].speculative = true;
88 op->more_files[1].vnode = AFS_FS_I(inode: d_inode(dentry: new));
89 op->more_files[1].speculative = true;
90 op->nr_files = 4;
91
92 op->dentry = old;
93 op->dentry_2 = new;
94 op->ops = &afs_silly_rename_operation;
95
96 trace_afs_silly_rename(vnode, done: false);
97 return afs_do_sync_operation(op);
98}
99
100/*
101 * Perform silly-rename of a dentry.
102 *
103 * AFS is stateless and the server doesn't know when the client is holding a
104 * file open. To prevent application problems when a file is unlinked while
105 * it's still open, the client performs a "silly-rename". That is, it renames
106 * the file to a hidden file in the same directory, and only performs the
107 * unlink once the last reference to it is put.
108 *
109 * The final cleanup is done during dentry_iput.
110 */
111int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
112 struct dentry *dentry, struct key *key)
113{
114 static unsigned int sillycounter;
115 struct dentry *sdentry = NULL;
116 unsigned char silly[16];
117 int ret = -EBUSY;
118
119 _enter("");
120
121 /* We don't allow a dentry to be silly-renamed twice. */
122 if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
123 return -EBUSY;
124
125 sdentry = NULL;
126 do {
127 dput(sdentry);
128 sillycounter++;
129
130 /* Create a silly name. Note that the ".__afs" prefix is
131 * understood by the salvager and must not be changed.
132 */
133 scnprintf(buf: silly, size: sizeof(silly), fmt: ".__afs%04X", sillycounter);
134 sdentry = lookup_noperm(&QSTR(silly), dentry->d_parent);
135
136 /* N.B. Better to return EBUSY here ... it could be dangerous
137 * to delete the file while it's in use.
138 */
139 if (IS_ERR(ptr: sdentry))
140 goto out;
141 } while (!d_is_negative(dentry: sdentry));
142
143 ihold(inode: &vnode->netfs.inode);
144
145 ret = afs_do_silly_rename(dvnode, vnode, old: dentry, new: sdentry, key);
146 switch (ret) {
147 case 0:
148 /* The rename succeeded. */
149 set_bit(AFS_VNODE_SILLY_DELETED, addr: &vnode->flags);
150 d_move(dentry, sdentry);
151 break;
152 case -ERESTARTSYS:
153 /* The result of the rename is unknown. Play it safe by forcing
154 * a new lookup.
155 */
156 d_drop(dentry);
157 d_drop(dentry: sdentry);
158 }
159
160 iput(&vnode->netfs.inode);
161 dput(sdentry);
162out:
163 _leave(" = %d", ret);
164 return ret;
165}
166
167static void afs_silly_unlink_success(struct afs_operation *op)
168{
169 _enter("op=%08x", op->debug_id);
170 afs_check_dir_conflict(op, dvp: &op->file[0]);
171 afs_vnode_commit_status(op, &op->file[0]);
172 afs_vnode_commit_status(op, &op->file[1]);
173 afs_update_dentry_version(op, dir_vp: &op->file[0], dentry: op->dentry);
174}
175
176static void afs_silly_unlink_edit_dir(struct afs_operation *op)
177{
178 struct afs_vnode_param *dvp = &op->file[0];
179 struct afs_vnode *dvnode = dvp->vnode;
180
181 _enter("op=%08x", op->debug_id);
182 down_write(sem: &dvnode->validate_lock);
183 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
184 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
185 afs_edit_dir_remove(dvnode, &op->dentry->d_name,
186 afs_edit_dir_for_unlink);
187 up_write(sem: &dvnode->validate_lock);
188}
189
190static const struct afs_operation_ops afs_silly_unlink_operation = {
191 .issue_afs_rpc = afs_fs_remove_file,
192 .issue_yfs_rpc = yfs_fs_remove_file,
193 .success = afs_silly_unlink_success,
194 .aborted = afs_check_for_remote_deletion,
195 .edit_dir = afs_silly_unlink_edit_dir,
196};
197
198/*
199 * Tell the server to remove a sillyrename file.
200 */
201static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
202 struct dentry *dentry, struct key *key)
203{
204 struct afs_operation *op;
205
206 _enter("");
207
208 op = afs_alloc_operation(NULL, dvnode->volume);
209 if (IS_ERR(ptr: op))
210 return PTR_ERR(ptr: op);
211
212 afs_op_set_vnode(op, n: 0, vnode: dvnode);
213 afs_op_set_vnode(op, n: 1, vnode);
214 op->file[0].dv_delta = 1;
215 op->file[0].modification = true;
216 op->file[0].update_ctime = true;
217 op->file[1].op_unlinked = true;
218 op->file[1].update_ctime = true;
219
220 op->dentry = dentry;
221 op->ops = &afs_silly_unlink_operation;
222
223 trace_afs_silly_rename(vnode, done: true);
224 afs_begin_vnode_operation(op);
225 afs_wait_for_operation(op);
226
227 /* If there was a conflict with a third party, check the status of the
228 * unlinked vnode.
229 */
230 if (op->cumul_error.error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
231 op->file[1].update_ctime = false;
232 op->fetch_status.which = 1;
233 op->ops = &afs_fetch_status_operation;
234 afs_begin_vnode_operation(op);
235 afs_wait_for_operation(op);
236 }
237
238 return afs_put_operation(op);
239}
240
241/*
242 * Remove sillyrename file on iput.
243 */
244int afs_silly_iput(struct dentry *dentry, struct inode *inode)
245{
246 struct afs_vnode *dvnode = AFS_FS_I(inode: d_inode(dentry: dentry->d_parent));
247 struct afs_vnode *vnode = AFS_FS_I(inode);
248 struct dentry *alias;
249 int ret;
250
251 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
252
253 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
254
255 down_read(sem: &dvnode->rmdir_lock);
256
257 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
258 if (IS_ERR(ptr: alias)) {
259 up_read(sem: &dvnode->rmdir_lock);
260 return 0;
261 }
262
263 if (!d_in_lookup(dentry: alias)) {
264 /* We raced with lookup... See if we need to transfer the
265 * sillyrename information to the aliased dentry.
266 */
267 ret = 0;
268 spin_lock(lock: &alias->d_lock);
269 if (d_really_is_positive(dentry: alias) &&
270 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
271 alias->d_flags |= DCACHE_NFSFS_RENAMED;
272 ret = 1;
273 }
274 spin_unlock(lock: &alias->d_lock);
275 up_read(sem: &dvnode->rmdir_lock);
276 dput(alias);
277 return ret;
278 }
279
280 /* Stop lock-release from complaining. */
281 spin_lock(lock: &vnode->lock);
282 vnode->lock_state = AFS_VNODE_LOCK_DELETED;
283 trace_afs_flock_ev(vnode, NULL, event: afs_flock_silly_delete, error: 0);
284 spin_unlock(lock: &vnode->lock);
285
286 afs_do_silly_unlink(dvnode, vnode, dentry, key: dvnode->silly_key);
287 up_read(sem: &dvnode->rmdir_lock);
288 d_lookup_done(dentry: alias);
289 dput(alias);
290 return 1;
291}
292

source code of linux/fs/afs/dir_silly.c