xref: /linux/fs/afs/file.c (revision 3f41368fbfe1b3d5922d317fe1a0a0cab6846802) 
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 	.release_folio	= netfs_release_folio,
58 	.invalidate_folio = netfs_invalidate_folio,
59 	.migrate_folio	= filemap_migrate_folio,
60 	.writepages	= afs_writepages,
61 };
62 
63 const struct address_space_operations afs_symlink_aops = {
64 	.read_folio	= afs_symlink_read_folio,
65 	.release_folio	= netfs_release_folio,
66 	.invalidate_folio = netfs_invalidate_folio,
67 	.migrate_folio	= filemap_migrate_folio,
68 };
69 
70 static const struct vm_operations_struct afs_vm_ops = {
71 	.open		= afs_vm_open,
72 	.close		= afs_vm_close,
73 	.fault		= filemap_fault,
74 	.map_pages	= afs_vm_map_pages,
75 	.page_mkwrite	= afs_page_mkwrite,
76 };
77 
78 /*
79  * Discard a pin on a writeback key.
80  */
81 void afs_put_wb_key(struct afs_wb_key *wbk)
82 {
83 	if (wbk && refcount_dec_and_test(&wbk->usage)) {
84 		key_put(wbk->key);
85 		kfree(wbk);
86 	}
87 }
88 
89 /*
90  * Cache key for writeback.
91  */
92 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
93 {
94 	struct afs_wb_key *wbk, *p;
95 
96 	wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
97 	if (!wbk)
98 		return -ENOMEM;
99 	refcount_set(&wbk->usage, 2);
100 	wbk->key = af->key;
101 
102 	spin_lock(&vnode->wb_lock);
103 	list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
104 		if (p->key == wbk->key)
105 			goto found;
106 	}
107 
108 	key_get(wbk->key);
109 	list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
110 	spin_unlock(&vnode->wb_lock);
111 	af->wb = wbk;
112 	return 0;
113 
114 found:
115 	refcount_inc(&p->usage);
116 	spin_unlock(&vnode->wb_lock);
117 	af->wb = p;
118 	kfree(wbk);
119 	return 0;
120 }
121 
122 /*
123  * open an AFS file or directory and attach a key to it
124  */
125 int afs_open(struct inode *inode, struct file *file)
126 {
127 	struct afs_vnode *vnode = AFS_FS_I(inode);
128 	struct afs_file *af;
129 	struct key *key;
130 	int ret;
131 
132 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
133 
134 	key = afs_request_key(vnode->volume->cell);
135 	if (IS_ERR(key)) {
136 		ret = PTR_ERR(key);
137 		goto error;
138 	}
139 
140 	af = kzalloc(sizeof(*af), GFP_KERNEL);
141 	if (!af) {
142 		ret = -ENOMEM;
143 		goto error_key;
144 	}
145 	af->key = key;
146 
147 	ret = afs_validate(vnode, key);
148 	if (ret < 0)
149 		goto error_af;
150 
151 	if (file->f_mode & FMODE_WRITE) {
152 		ret = afs_cache_wb_key(vnode, af);
153 		if (ret < 0)
154 			goto error_af;
155 	}
156 
157 	if (file->f_flags & O_TRUNC)
158 		set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
159 
160 	fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);
161 
162 	file->private_data = af;
163 	_leave(" = 0");
164 	return 0;
165 
166 error_af:
167 	kfree(af);
168 error_key:
169 	key_put(key);
170 error:
171 	_leave(" = %d", ret);
172 	return ret;
173 }
174 
175 /*
176  * release an AFS file or directory and discard its key
177  */
178 int afs_release(struct inode *inode, struct file *file)
179 {
180 	struct afs_vnode_cache_aux aux;
181 	struct afs_vnode *vnode = AFS_FS_I(inode);
182 	struct afs_file *af = file->private_data;
183 	loff_t i_size;
184 	int ret = 0;
185 
186 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
187 
188 	if ((file->f_mode & FMODE_WRITE))
189 		ret = vfs_fsync(file, 0);
190 
191 	file->private_data = NULL;
192 	if (af->wb)
193 		afs_put_wb_key(af->wb);
194 
195 	if ((file->f_mode & FMODE_WRITE)) {
196 		i_size = i_size_read(&vnode->netfs.inode);
197 		afs_set_cache_aux(vnode, &aux);
198 		fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
199 	} else {
200 		fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
201 	}
202 
203 	key_put(af->key);
204 	kfree(af);
205 	afs_prune_wb_keys(vnode);
206 	_leave(" = %d", ret);
207 	return ret;
208 }
209 
210 /*
211  * Allocate a new read record.
212  */
213 struct afs_read *afs_alloc_read(gfp_t gfp)
214 {
215 	struct afs_read *req;
216 
217 	req = kzalloc(sizeof(struct afs_read), gfp);
218 	if (req)
219 		refcount_set(&req->usage, 1);
220 
221 	return req;
222 }
223 
224 /*
225  * Dispose of a ref to a read record.
226  */
227 void afs_put_read(struct afs_read *req)
228 {
229 	if (refcount_dec_and_test(&req->usage)) {
230 		if (req->cleanup)
231 			req->cleanup(req);
232 		key_put(req->key);
233 		kfree(req);
234 	}
235 }
236 
237 static void afs_fetch_data_notify(struct afs_operation *op)
238 {
239 	struct afs_read *req = op->fetch.req;
240 	struct netfs_io_subrequest *subreq = req->subreq;
241 	int error = afs_op_error(op);
242 
243 	req->error = error;
244 	if (subreq) {
245 		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
246 		netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
247 		req->subreq = NULL;
248 	} else if (req->done) {
249 		req->done(req);
250 	}
251 }
252 
253 static void afs_fetch_data_success(struct afs_operation *op)
254 {
255 	struct afs_vnode *vnode = op->file[0].vnode;
256 
257 	_enter("op=%08x", op->debug_id);
258 	afs_vnode_commit_status(op, &op->file[0]);
259 	afs_stat_v(vnode, n_fetches);
260 	atomic_long_add(op->fetch.req->actual_len, &op->net->n_fetch_bytes);
261 	afs_fetch_data_notify(op);
262 }
263 
264 static void afs_fetch_data_put(struct afs_operation *op)
265 {
266 	op->fetch.req->error = afs_op_error(op);
267 	afs_put_read(op->fetch.req);
268 }
269 
270 static const struct afs_operation_ops afs_fetch_data_operation = {
271 	.issue_afs_rpc	= afs_fs_fetch_data,
272 	.issue_yfs_rpc	= yfs_fs_fetch_data,
273 	.success	= afs_fetch_data_success,
274 	.aborted	= afs_check_for_remote_deletion,
275 	.failed		= afs_fetch_data_notify,
276 	.put		= afs_fetch_data_put,
277 };
278 
279 /*
280  * Fetch file data from the volume.
281  */
282 int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
283 {
284 	struct afs_operation *op;
285 
286 	_enter("%s{%llx:%llu.%u},%x,,,",
287 	       vnode->volume->name,
288 	       vnode->fid.vid,
289 	       vnode->fid.vnode,
290 	       vnode->fid.unique,
291 	       key_serial(req->key));
292 
293 	op = afs_alloc_operation(req->key, vnode->volume);
294 	if (IS_ERR(op)) {
295 		if (req->subreq)
296 			netfs_subreq_terminated(req->subreq, PTR_ERR(op), false);
297 		return PTR_ERR(op);
298 	}
299 
300 	afs_op_set_vnode(op, 0, vnode);
301 
302 	op->fetch.req	= afs_get_read(req);
303 	op->ops		= &afs_fetch_data_operation;
304 	return afs_do_sync_operation(op);
305 }
306 
307 static void afs_issue_read(struct netfs_io_subrequest *subreq)
308 {
309 	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
310 	struct afs_read *fsreq;
311 
312 	fsreq = afs_alloc_read(GFP_NOFS);
313 	if (!fsreq)
314 		return netfs_subreq_terminated(subreq, -ENOMEM, false);
315 
316 	fsreq->subreq	= subreq;
317 	fsreq->pos	= subreq->start + subreq->transferred;
318 	fsreq->len	= subreq->len   - subreq->transferred;
319 	fsreq->key	= key_get(subreq->rreq->netfs_priv);
320 	fsreq->vnode	= vnode;
321 	fsreq->iter	= &subreq->io_iter;
322 
323 	afs_fetch_data(fsreq->vnode, fsreq);
324 	afs_put_read(fsreq);
325 }
326 
327 static int afs_symlink_read_folio(struct file *file, struct folio *folio)
328 {
329 	struct afs_vnode *vnode = AFS_FS_I(folio->mapping->host);
330 	struct afs_read *fsreq;
331 	int ret;
332 
333 	fsreq = afs_alloc_read(GFP_NOFS);
334 	if (!fsreq)
335 		return -ENOMEM;
336 
337 	fsreq->pos	= folio_pos(folio);
338 	fsreq->len	= folio_size(folio);
339 	fsreq->vnode	= vnode;
340 	fsreq->iter	= &fsreq->def_iter;
341 	iov_iter_xarray(&fsreq->def_iter, ITER_DEST, &folio->mapping->i_pages,
342 			fsreq->pos, fsreq->len);
343 
344 	ret = afs_fetch_data(fsreq->vnode, fsreq);
345 	if (ret == 0)
346 		folio_mark_uptodate(folio);
347 	folio_unlock(folio);
348 	return ret;
349 }
350 
351 static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
352 {
353 	if (file)
354 		rreq->netfs_priv = key_get(afs_file_key(file));
355 	rreq->rsize = 256 * 1024;
356 	rreq->wsize = 256 * 1024 * 1024;
357 	return 0;
358 }
359 
360 static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
361 				 struct folio **foliop, void **_fsdata)
362 {
363 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
364 
365 	return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
366 }
367 
368 static void afs_free_request(struct netfs_io_request *rreq)
369 {
370 	key_put(rreq->netfs_priv);
371 	afs_put_wb_key(rreq->netfs_priv2);
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 	.begin_writeback	= afs_begin_writeback,
404 	.prepare_write		= afs_prepare_write,
405 	.issue_write		= afs_issue_write,
406 };
407 
408 static void afs_add_open_mmap(struct afs_vnode *vnode)
409 {
410 	if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
411 		down_write(&vnode->volume->open_mmaps_lock);
412 
413 		if (list_empty(&vnode->cb_mmap_link))
414 			list_add_tail(&vnode->cb_mmap_link, &vnode->volume->open_mmaps);
415 
416 		up_write(&vnode->volume->open_mmaps_lock);
417 	}
418 }
419 
420 static void afs_drop_open_mmap(struct afs_vnode *vnode)
421 {
422 	if (atomic_add_unless(&vnode->cb_nr_mmap, -1, 1))
423 		return;
424 
425 	down_write(&vnode->volume->open_mmaps_lock);
426 
427 	read_seqlock_excl(&vnode->cb_lock);
428 	// the only place where ->cb_nr_mmap may hit 0
429 	// see __afs_break_callback() for the other side...
430 	if (atomic_dec_and_test(&vnode->cb_nr_mmap))
431 		list_del_init(&vnode->cb_mmap_link);
432 	read_sequnlock_excl(&vnode->cb_lock);
433 
434 	up_write(&vnode->volume->open_mmaps_lock);
435 	flush_work(&vnode->cb_work);
436 }
437 
438 /*
439  * Handle setting up a memory mapping on an AFS file.
440  */
441 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
442 {
443 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
444 	int ret;
445 
446 	afs_add_open_mmap(vnode);
447 
448 	ret = generic_file_mmap(file, vma);
449 	if (ret == 0)
450 		vma->vm_ops = &afs_vm_ops;
451 	else
452 		afs_drop_open_mmap(vnode);
453 	return ret;
454 }
455 
456 static void afs_vm_open(struct vm_area_struct *vma)
457 {
458 	afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
459 }
460 
461 static void afs_vm_close(struct vm_area_struct *vma)
462 {
463 	afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
464 }
465 
466 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff)
467 {
468 	struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file));
469 
470 	if (afs_check_validity(vnode))
471 		return filemap_map_pages(vmf, start_pgoff, end_pgoff);
472 	return 0;
473 }
474 
475 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
476 {
477 	struct inode *inode = file_inode(iocb->ki_filp);
478 	struct afs_vnode *vnode = AFS_FS_I(inode);
479 	struct afs_file *af = iocb->ki_filp->private_data;
480 	ssize_t ret;
481 
482 	if (iocb->ki_flags & IOCB_DIRECT)
483 		return netfs_unbuffered_read_iter(iocb, iter);
484 
485 	ret = netfs_start_io_read(inode);
486 	if (ret < 0)
487 		return ret;
488 	ret = afs_validate(vnode, af->key);
489 	if (ret == 0)
490 		ret = filemap_read(iocb, iter, 0);
491 	netfs_end_io_read(inode);
492 	return ret;
493 }
494 
495 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
496 				    struct pipe_inode_info *pipe,
497 				    size_t len, unsigned int flags)
498 {
499 	struct inode *inode = file_inode(in);
500 	struct afs_vnode *vnode = AFS_FS_I(inode);
501 	struct afs_file *af = in->private_data;
502 	ssize_t ret;
503 
504 	ret = netfs_start_io_read(inode);
505 	if (ret < 0)
506 		return ret;
507 	ret = afs_validate(vnode, af->key);
508 	if (ret == 0)
509 		ret = filemap_splice_read(in, ppos, pipe, len, flags);
510 	netfs_end_io_read(inode);
511 	return ret;
512 }
513