xref: /linux/fs/afs/file.c (revision 6d9b262afe0ec1d6e0ef99321ca9d6b921310471) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS filesystem file handling
3  *
4  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/fs.h>
12 #include <linux/pagemap.h>
13 #include <linux/writeback.h>
14 #include <linux/gfp.h>
15 #include <linux/task_io_accounting_ops.h>
16 #include <linux/mm.h>
17 #include <linux/swap.h>
18 #include <linux/netfs.h>
19 #include "internal.h"
20 
21 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
22 static int afs_symlink_read_folio(struct file *file, struct folio *folio);
23 
24 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
25 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
26 				    struct pipe_inode_info *pipe,
27 				    size_t len, unsigned int flags);
28 static void afs_vm_open(struct vm_area_struct *area);
29 static void afs_vm_close(struct vm_area_struct *area);
30 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);
31 
32 const struct file_operations afs_file_operations = {
33 	.open		= afs_open,
34 	.release	= afs_release,
35 	.llseek		= generic_file_llseek,
36 	.read_iter	= afs_file_read_iter,
37 	.write_iter	= netfs_file_write_iter,
38 	.mmap		= afs_file_mmap,
39 	.splice_read	= afs_file_splice_read,
40 	.splice_write	= iter_file_splice_write,
41 	.fsync		= afs_fsync,
42 	.lock		= afs_lock,
43 	.flock		= afs_flock,
44 };
45 
46 const struct inode_operations afs_file_inode_operations = {
47 	.getattr	= afs_getattr,
48 	.setattr	= afs_setattr,
49 	.permission	= afs_permission,
50 };
51 
52 const struct address_space_operations afs_file_aops = {
53 	.direct_IO	= noop_direct_IO,
54 	.read_folio	= netfs_read_folio,
55 	.readahead	= netfs_readahead,
56 	.dirty_folio	= netfs_dirty_folio,
57 	.launder_folio	= netfs_launder_folio,
58 	.release_folio	= netfs_release_folio,
59 	.invalidate_folio = netfs_invalidate_folio,
60 	.migrate_folio	= filemap_migrate_folio,
61 	.writepages	= afs_writepages,
62 };
63 
64 const struct address_space_operations afs_symlink_aops = {
65 	.read_folio	= afs_symlink_read_folio,
66 	.release_folio	= netfs_release_folio,
67 	.invalidate_folio = netfs_invalidate_folio,
68 	.migrate_folio	= filemap_migrate_folio,
69 };
70 
71 static const struct vm_operations_struct afs_vm_ops = {
72 	.open		= afs_vm_open,
73 	.close		= afs_vm_close,
74 	.fault		= filemap_fault,
75 	.map_pages	= afs_vm_map_pages,
76 	.page_mkwrite	= afs_page_mkwrite,
77 };
78 
79 /*
80  * Discard a pin on a writeback key.
81  */
82 void afs_put_wb_key(struct afs_wb_key *wbk)
83 {
84 	if (wbk && refcount_dec_and_test(&wbk->usage)) {
85 		key_put(wbk->key);
86 		kfree(wbk);
87 	}
88 }
89 
90 /*
91  * Cache key for writeback.
92  */
93 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
94 {
95 	struct afs_wb_key *wbk, *p;
96 
97 	wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
98 	if (!wbk)
99 		return -ENOMEM;
100 	refcount_set(&wbk->usage, 2);
101 	wbk->key = af->key;
102 
103 	spin_lock(&vnode->wb_lock);
104 	list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
105 		if (p->key == wbk->key)
106 			goto found;
107 	}
108 
109 	key_get(wbk->key);
110 	list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
111 	spin_unlock(&vnode->wb_lock);
112 	af->wb = wbk;
113 	return 0;
114 
115 found:
116 	refcount_inc(&p->usage);
117 	spin_unlock(&vnode->wb_lock);
118 	af->wb = p;
119 	kfree(wbk);
120 	return 0;
121 }
122 
123 /*
124  * open an AFS file or directory and attach a key to it
125  */
126 int afs_open(struct inode *inode, struct file *file)
127 {
128 	struct afs_vnode *vnode = AFS_FS_I(inode);
129 	struct afs_file *af;
130 	struct key *key;
131 	int ret;
132 
133 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
134 
135 	key = afs_request_key(vnode->volume->cell);
136 	if (IS_ERR(key)) {
137 		ret = PTR_ERR(key);
138 		goto error;
139 	}
140 
141 	af = kzalloc(sizeof(*af), GFP_KERNEL);
142 	if (!af) {
143 		ret = -ENOMEM;
144 		goto error_key;
145 	}
146 	af->key = key;
147 
148 	ret = afs_validate(vnode, key);
149 	if (ret < 0)
150 		goto error_af;
151 
152 	if (file->f_mode & FMODE_WRITE) {
153 		ret = afs_cache_wb_key(vnode, af);
154 		if (ret < 0)
155 			goto error_af;
156 	}
157 
158 	if (file->f_flags & O_TRUNC)
159 		set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
160 
161 	fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);
162 
163 	file->private_data = af;
164 	_leave(" = 0");
165 	return 0;
166 
167 error_af:
168 	kfree(af);
169 error_key:
170 	key_put(key);
171 error:
172 	_leave(" = %d", ret);
173 	return ret;
174 }
175 
176 /*
177  * release an AFS file or directory and discard its key
178  */
179 int afs_release(struct inode *inode, struct file *file)
180 {
181 	struct afs_vnode_cache_aux aux;
182 	struct afs_vnode *vnode = AFS_FS_I(inode);
183 	struct afs_file *af = file->private_data;
184 	loff_t i_size;
185 	int ret = 0;
186 
187 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
188 
189 	if ((file->f_mode & FMODE_WRITE))
190 		ret = vfs_fsync(file, 0);
191 
192 	file->private_data = NULL;
193 	if (af->wb)
194 		afs_put_wb_key(af->wb);
195 
196 	if ((file->f_mode & FMODE_WRITE)) {
197 		i_size = i_size_read(&vnode->netfs.inode);
198 		afs_set_cache_aux(vnode, &aux);
199 		fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
200 	} else {
201 		fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
202 	}
203 
204 	key_put(af->key);
205 	kfree(af);
206 	afs_prune_wb_keys(vnode);
207 	_leave(" = %d", ret);
208 	return ret;
209 }
210 
211 /*
212  * Allocate a new read record.
213  */
214 struct afs_read *afs_alloc_read(gfp_t gfp)
215 {
216 	struct afs_read *req;
217 
218 	req = kzalloc(sizeof(struct afs_read), gfp);
219 	if (req)
220 		refcount_set(&req->usage, 1);
221 
222 	return req;
223 }
224 
225 /*
226  * Dispose of a ref to a read record.
227  */
228 void afs_put_read(struct afs_read *req)
229 {
230 	if (refcount_dec_and_test(&req->usage)) {
231 		if (req->cleanup)
232 			req->cleanup(req);
233 		key_put(req->key);
234 		kfree(req);
235 	}
236 }
237 
238 static void afs_fetch_data_notify(struct afs_operation *op)
239 {
240 	struct afs_read *req = op->fetch.req;
241 	struct netfs_io_subrequest *subreq = req->subreq;
242 	int error = afs_op_error(op);
243 
244 	req->error = error;
245 	if (subreq) {
246 		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
247 		netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
248 		req->subreq = NULL;
249 	} else if (req->done) {
250 		req->done(req);
251 	}
252 }
253 
254 static void afs_fetch_data_success(struct afs_operation *op)
255 {
256 	struct afs_vnode *vnode = op->file[0].vnode;
257 
258 	_enter("op=%08x", op->debug_id);
259 	afs_vnode_commit_status(op, &op->file[0]);
260 	afs_stat_v(vnode, n_fetches);
261 	atomic_long_add(op->fetch.req->actual_len, &op->net->n_fetch_bytes);
262 	afs_fetch_data_notify(op);
263 }
264 
265 static void afs_fetch_data_put(struct afs_operation *op)
266 {
267 	op->fetch.req->error = afs_op_error(op);
268 	afs_put_read(op->fetch.req);
269 }
270 
271 static const struct afs_operation_ops afs_fetch_data_operation = {
272 	.issue_afs_rpc	= afs_fs_fetch_data,
273 	.issue_yfs_rpc	= yfs_fs_fetch_data,
274 	.success	= afs_fetch_data_success,
275 	.aborted	= afs_check_for_remote_deletion,
276 	.failed		= afs_fetch_data_notify,
277 	.put		= afs_fetch_data_put,
278 };
279 
280 /*
281  * Fetch file data from the volume.
282  */
283 int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
284 {
285 	struct afs_operation *op;
286 
287 	_enter("%s{%llx:%llu.%u},%x,,,",
288 	       vnode->volume->name,
289 	       vnode->fid.vid,
290 	       vnode->fid.vnode,
291 	       vnode->fid.unique,
292 	       key_serial(req->key));
293 
294 	op = afs_alloc_operation(req->key, vnode->volume);
295 	if (IS_ERR(op)) {
296 		if (req->subreq)
297 			netfs_subreq_terminated(req->subreq, PTR_ERR(op), false);
298 		return PTR_ERR(op);
299 	}
300 
301 	afs_op_set_vnode(op, 0, vnode);
302 
303 	op->fetch.req	= afs_get_read(req);
304 	op->ops		= &afs_fetch_data_operation;
305 	return afs_do_sync_operation(op);
306 }
307 
308 static void afs_issue_read(struct netfs_io_subrequest *subreq)
309 {
310 	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
311 	struct afs_read *fsreq;
312 
313 	fsreq = afs_alloc_read(GFP_NOFS);
314 	if (!fsreq)
315 		return netfs_subreq_terminated(subreq, -ENOMEM, false);
316 
317 	fsreq->subreq	= subreq;
318 	fsreq->pos	= subreq->start + subreq->transferred;
319 	fsreq->len	= subreq->len   - subreq->transferred;
320 	fsreq->key	= key_get(subreq->rreq->netfs_priv);
321 	fsreq->vnode	= vnode;
322 	fsreq->iter	= &subreq->io_iter;
323 
324 	afs_fetch_data(fsreq->vnode, fsreq);
325 	afs_put_read(fsreq);
326 }
327 
328 static int afs_symlink_read_folio(struct file *file, struct folio *folio)
329 {
330 	struct afs_vnode *vnode = AFS_FS_I(folio->mapping->host);
331 	struct afs_read *fsreq;
332 	int ret;
333 
334 	fsreq = afs_alloc_read(GFP_NOFS);
335 	if (!fsreq)
336 		return -ENOMEM;
337 
338 	fsreq->pos	= folio_pos(folio);
339 	fsreq->len	= folio_size(folio);
340 	fsreq->vnode	= vnode;
341 	fsreq->iter	= &fsreq->def_iter;
342 	iov_iter_xarray(&fsreq->def_iter, ITER_DEST, &folio->mapping->i_pages,
343 			fsreq->pos, fsreq->len);
344 
345 	ret = afs_fetch_data(fsreq->vnode, fsreq);
346 	if (ret == 0)
347 		folio_mark_uptodate(folio);
348 	folio_unlock(folio);
349 	return ret;
350 }
351 
352 static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
353 {
354 	if (file)
355 		rreq->netfs_priv = key_get(afs_file_key(file));
356 	rreq->rsize = 256 * 1024;
357 	rreq->wsize = 256 * 1024;
358 	return 0;
359 }
360 
361 static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
362 				 struct folio **foliop, void **_fsdata)
363 {
364 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
365 
366 	return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
367 }
368 
369 static void afs_free_request(struct netfs_io_request *rreq)
370 {
371 	key_put(rreq->netfs_priv);
372 }
373 
374 static void afs_update_i_size(struct inode *inode, loff_t new_i_size)
375 {
376 	struct afs_vnode *vnode = AFS_FS_I(inode);
377 	loff_t i_size;
378 
379 	write_seqlock(&vnode->cb_lock);
380 	i_size = i_size_read(&vnode->netfs.inode);
381 	if (new_i_size > i_size) {
382 		i_size_write(&vnode->netfs.inode, new_i_size);
383 		inode_set_bytes(&vnode->netfs.inode, new_i_size);
384 	}
385 	write_sequnlock(&vnode->cb_lock);
386 	fscache_update_cookie(afs_vnode_cache(vnode), NULL, &new_i_size);
387 }
388 
389 static void afs_netfs_invalidate_cache(struct netfs_io_request *wreq)
390 {
391 	struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
392 
393 	afs_invalidate_cache(vnode, 0);
394 }
395 
396 const struct netfs_request_ops afs_req_ops = {
397 	.init_request		= afs_init_request,
398 	.free_request		= afs_free_request,
399 	.check_write_begin	= afs_check_write_begin,
400 	.issue_read		= afs_issue_read,
401 	.update_i_size		= afs_update_i_size,
402 	.invalidate_cache	= afs_netfs_invalidate_cache,
403 	.create_write_requests	= afs_create_write_requests,
404 };
405 
406 static void afs_add_open_mmap(struct afs_vnode *vnode)
407 {
408 	if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
409 		down_write(&vnode->volume->open_mmaps_lock);
410 
411 		if (list_empty(&vnode->cb_mmap_link))
412 			list_add_tail(&vnode->cb_mmap_link, &vnode->volume->open_mmaps);
413 
414 		up_write(&vnode->volume->open_mmaps_lock);
415 	}
416 }
417 
418 static void afs_drop_open_mmap(struct afs_vnode *vnode)
419 {
420 	if (atomic_add_unless(&vnode->cb_nr_mmap, -1, 1))
421 		return;
422 
423 	down_write(&vnode->volume->open_mmaps_lock);
424 
425 	read_seqlock_excl(&vnode->cb_lock);
426 	// the only place where ->cb_nr_mmap may hit 0
427 	// see __afs_break_callback() for the other side...
428 	if (atomic_dec_and_test(&vnode->cb_nr_mmap))
429 		list_del_init(&vnode->cb_mmap_link);
430 	read_sequnlock_excl(&vnode->cb_lock);
431 
432 	up_write(&vnode->volume->open_mmaps_lock);
433 	flush_work(&vnode->cb_work);
434 }
435 
436 /*
437  * Handle setting up a memory mapping on an AFS file.
438  */
439 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
440 {
441 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
442 	int ret;
443 
444 	afs_add_open_mmap(vnode);
445 
446 	ret = generic_file_mmap(file, vma);
447 	if (ret == 0)
448 		vma->vm_ops = &afs_vm_ops;
449 	else
450 		afs_drop_open_mmap(vnode);
451 	return ret;
452 }
453 
454 static void afs_vm_open(struct vm_area_struct *vma)
455 {
456 	afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
457 }
458 
459 static void afs_vm_close(struct vm_area_struct *vma)
460 {
461 	afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
462 }
463 
464 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff)
465 {
466 	struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file));
467 
468 	if (afs_check_validity(vnode))
469 		return filemap_map_pages(vmf, start_pgoff, end_pgoff);
470 	return 0;
471 }
472 
473 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
474 {
475 	struct inode *inode = file_inode(iocb->ki_filp);
476 	struct afs_vnode *vnode = AFS_FS_I(inode);
477 	struct afs_file *af = iocb->ki_filp->private_data;
478 	ssize_t ret;
479 
480 	if (iocb->ki_flags & IOCB_DIRECT)
481 		return netfs_unbuffered_read_iter(iocb, iter);
482 
483 	ret = netfs_start_io_read(inode);
484 	if (ret < 0)
485 		return ret;
486 	ret = afs_validate(vnode, af->key);
487 	if (ret == 0)
488 		ret = filemap_read(iocb, iter, 0);
489 	netfs_end_io_read(inode);
490 	return ret;
491 }
492 
493 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
494 				    struct pipe_inode_info *pipe,
495 				    size_t len, unsigned int flags)
496 {
497 	struct inode *inode = file_inode(in);
498 	struct afs_vnode *vnode = AFS_FS_I(inode);
499 	struct afs_file *af = in->private_data;
500 	ssize_t ret;
501 
502 	ret = netfs_start_io_read(inode);
503 	if (ret < 0)
504 		return ret;
505 	ret = afs_validate(vnode, af->key);
506 	if (ret == 0)
507 		ret = filemap_splice_read(in, ppos, pipe, len, flags);
508 	netfs_end_io_read(inode);
509 	return ret;
510 }
511