xref: /openbmc/linux/fs/afs/dir_silly.c (revision 874c8ca1)
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 		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 
afs_silly_unlink_success(struct afs_operation * op)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 
afs_silly_unlink_edit_dir(struct afs_operation * op)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  */
afs_do_silly_unlink(struct afs_vnode * dvnode,struct afs_vnode * vnode,struct dentry * dentry,struct key * key)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->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  */
afs_silly_iput(struct dentry * dentry,struct inode * inode)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