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
21static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
22static int afs_symlink_read_folio(struct file *file, struct folio *folio);
23
24static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
25static 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);
28static void afs_vm_open(struct vm_area_struct *area);
29static void afs_vm_close(struct vm_area_struct *area);
30static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);
31
32const 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
46const struct inode_operations afs_file_inode_operations = {
47	.getattr	= afs_getattr,
48	.setattr	= afs_setattr,
49	.permission	= afs_permission,
50};
51
52const 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
64const 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
71static 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 */
82void 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 */
93int 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
115found:
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 */
126int 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
167error_af:
168	kfree(af);
169error_key:
170	key_put(key);
171error:
172	_leave(" = %d", ret);
173	return ret;
174}
175
176/*
177 * release an AFS file or directory and discard its key
178 */
179int 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 */
214struct 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 */
228void 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
238static 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
254static 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
265static 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
271static 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 */
283int 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
308static 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
328static 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
352static 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
361static 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
369static void afs_free_request(struct netfs_io_request *rreq)
370{
371	key_put(rreq->netfs_priv);
372}
373
374static 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
389static 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
396const 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
406static 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
418static 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 */
439static 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
454static 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
459static 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
464static 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
473static 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
493static 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