dir_silly.c

  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, &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(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
 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(op))
 70		return PTR_ERR(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, 0, dvnode);
 79	afs_op_set_vnode(op, 1, 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(d_inode(old));
 87	op->more_files[0].speculative	= true;
 88	op->more_files[1].vnode		= AFS_FS_I(d_inode(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, 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(silly, sizeof(silly), ".__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(sdentry))
140			goto out;
141	} while (!d_is_negative(sdentry));
142
143	ihold(&vnode->netfs.inode);
144
145	ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
146	switch (ret) {
147	case 0:
148		/* The rename succeeded. */
149		set_bit(AFS_VNODE_SILLY_DELETED, &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(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, &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, &op->file[0], 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(&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(&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(op))
210		return PTR_ERR(op);
211
212	afs_op_set_vnode(op, 0, dvnode);
213	afs_op_set_vnode(op, 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, 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(d_inode(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(&dvnode->rmdir_lock);
256
257	alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
258	if (IS_ERR(alias)) {
259		up_read(&dvnode->rmdir_lock);
260		return 0;
261	}
262
263	if (!d_in_lookup(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(&alias->d_lock);
269		if (d_really_is_positive(alias) &&
270		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
271			alias->d_flags |= DCACHE_NFSFS_RENAMED;
272			ret = 1;
273		}
274		spin_unlock(&alias->d_lock);
275		up_read(&dvnode->rmdir_lock);
276		dput(alias);
277		return ret;
278	}
279
280	/* Stop lock-release from complaining. */
281	spin_lock(&vnode->lock);
282	vnode->lock_state = AFS_VNODE_LOCK_DELETED;
283	trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
284	spin_unlock(&vnode->lock);
285
286	afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
287	up_read(&dvnode->rmdir_lock);
288	d_lookup_done(alias);
289	dput(alias);
290	return 1;
291}