summaryrefslogtreecommitdiff
path: root/fs/erofs/fscache.c
blob: bc12030393b24f26231fb363ac07e3150cd6babb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2022, Alibaba Cloud
 * Copyright (C) 2022, Bytedance Inc. All rights reserved.
 */
#include <linux/fscache.h>
#include "internal.h"

static DEFINE_MUTEX(erofs_domain_list_lock);
static DEFINE_MUTEX(erofs_domain_cookies_lock);
static LIST_HEAD(erofs_domain_list);
static LIST_HEAD(erofs_domain_cookies_list);
static struct vfsmount *erofs_pseudo_mnt;

struct erofs_fscache_request {
	struct erofs_fscache_request *primary;
	struct netfs_cache_resources cache_resources;
	struct address_space	*mapping;	/* The mapping being accessed */
	loff_t			start;		/* Start position */
	size_t			len;		/* Length of the request */
	size_t			submitted;	/* Length of submitted */
	short			error;		/* 0 or error that occurred */
	refcount_t		ref;
};

static struct erofs_fscache_request *erofs_fscache_req_alloc(struct address_space *mapping,
					     loff_t start, size_t len)
{
	struct erofs_fscache_request *req;

	req = kzalloc(sizeof(struct erofs_fscache_request), GFP_KERNEL);
	if (!req)
		return ERR_PTR(-ENOMEM);

	req->mapping = mapping;
	req->start   = start;
	req->len     = len;
	refcount_set(&req->ref, 1);

	return req;
}

static struct erofs_fscache_request *erofs_fscache_req_chain(struct erofs_fscache_request *primary,
					     size_t len)
{
	struct erofs_fscache_request *req;

	/* use primary request for the first submission */
	if (!primary->submitted) {
		refcount_inc(&primary->ref);
		return primary;
	}

	req = erofs_fscache_req_alloc(primary->mapping,
			primary->start + primary->submitted, len);
	if (!IS_ERR(req)) {
		req->primary = primary;
		refcount_inc(&primary->ref);
	}
	return req;
}

static void erofs_fscache_req_complete(struct erofs_fscache_request *req)
{
	struct folio *folio;
	bool failed = req->error;
	pgoff_t start_page = req->start / PAGE_SIZE;
	pgoff_t last_page = ((req->start + req->len) / PAGE_SIZE) - 1;

	XA_STATE(xas, &req->mapping->i_pages, start_page);

	rcu_read_lock();
	xas_for_each(&xas, folio, last_page) {
		if (xas_retry(&xas, folio))
			continue;
		if (!failed)
			folio_mark_uptodate(folio);
		folio_unlock(folio);
	}
	rcu_read_unlock();
}

static void erofs_fscache_req_put(struct erofs_fscache_request *req)
{
	if (refcount_dec_and_test(&req->ref)) {
		if (req->cache_resources.ops)
			req->cache_resources.ops->end_operation(&req->cache_resources);
		if (!req->primary)
			erofs_fscache_req_complete(req);
		else
			erofs_fscache_req_put(req->primary);
		kfree(req);
	}
}

static void erofs_fscache_subreq_complete(void *priv,
		ssize_t transferred_or_error, bool was_async)
{
	struct erofs_fscache_request *req = priv;

	if (IS_ERR_VALUE(transferred_or_error)) {
		if (req->primary)
			req->primary->error = transferred_or_error;
		else
			req->error = transferred_or_error;
	}
	erofs_fscache_req_put(req);
}

/*
 * Read data from fscache (cookie, pstart, len), and fill the read data into
 * page cache described by (req->mapping, lstart, len). @pstart describeis the
 * start physical address in the cache file.
 */
static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
		struct erofs_fscache_request *req, loff_t pstart, size_t len)
{
	enum netfs_io_source source;
	struct super_block *sb = req->mapping->host->i_sb;
	struct netfs_cache_resources *cres = &req->cache_resources;
	struct iov_iter iter;
	loff_t lstart = req->start + req->submitted;
	size_t done = 0;
	int ret;

	DBG_BUGON(len > req->len - req->submitted);

	ret = fscache_begin_read_operation(cres, cookie);
	if (ret)
		return ret;

	while (done < len) {
		loff_t sstart = pstart + done;
		size_t slen = len - done;
		unsigned long flags = 1 << NETFS_SREQ_ONDEMAND;

		source = cres->ops->prepare_ondemand_read(cres,
				sstart, &slen, LLONG_MAX, &flags, 0);
		if (WARN_ON(slen == 0))
			source = NETFS_INVALID_READ;
		if (source != NETFS_READ_FROM_CACHE) {
			erofs_err(sb, "failed to fscache prepare_read (source %d)", source);
			return -EIO;
		}

		refcount_inc(&req->ref);
		iov_iter_xarray(&iter, ITER_DEST, &req->mapping->i_pages,
				lstart + done, slen);

		ret = fscache_read(cres, sstart, &iter, NETFS_READ_HOLE_FAIL,
				   erofs_fscache_subreq_complete, req);
		if (ret == -EIOCBQUEUED)
			ret = 0;
		if (ret) {
			erofs_err(sb, "failed to fscache_read (ret %d)", ret);
			return ret;
		}

		done += slen;
	}
	DBG_BUGON(done != len);
	return 0;
}

static int erofs_fscache_meta_read_folio(struct file *data, struct folio *folio)
{
	int ret;
	struct erofs_fscache *ctx = folio->mapping->host->i_private;
	struct erofs_fscache_request *req;

	req = erofs_fscache_req_alloc(folio->mapping,
				folio_pos(folio), folio_size(folio));
	if (IS_ERR(req)) {
		folio_unlock(folio);
		return PTR_ERR(req);
	}

	ret = erofs_fscache_read_folios_async(ctx->cookie, req,
				folio_pos(folio), folio_size(folio));
	if (ret)
		req->error = ret;

	erofs_fscache_req_put(req);
	return ret;
}

static int erofs_fscache_data_read_slice(struct erofs_fscache_request *primary)
{
	struct address_space *mapping = primary->mapping;
	struct inode *inode = mapping->host;
	struct super_block *sb = inode->i_sb;
	struct erofs_fscache_request *req;
	struct erofs_map_blocks map;
	struct erofs_map_dev mdev;
	struct iov_iter iter;
	loff_t pos = primary->start + primary->submitted;
	size_t count;
	int ret;

	map.m_la = pos;
	ret = erofs_map_blocks(inode, &map);
	if (ret)
		return ret;

	if (map.m_flags & EROFS_MAP_META) {
		struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
		erofs_blk_t blknr;
		size_t offset, size;
		void *src;

		/* For tail packing layout, the offset may be non-zero. */
		offset = erofs_blkoff(sb, map.m_pa);
		blknr = erofs_blknr(sb, map.m_pa);
		size = map.m_llen;

		src = erofs_read_metabuf(&buf, sb, blknr, EROFS_KMAP);
		if (IS_ERR(src))
			return PTR_ERR(src);

		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, PAGE_SIZE);
		if (copy_to_iter(src + offset, size, &iter) != size) {
			erofs_put_metabuf(&buf);
			return -EFAULT;
		}
		iov_iter_zero(PAGE_SIZE - size, &iter);
		erofs_put_metabuf(&buf);
		primary->submitted += PAGE_SIZE;
		return 0;
	}

	count = primary->len - primary->submitted;
	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, count);
		iov_iter_zero(count, &iter);
		primary->submitted += count;
		return 0;
	}

	count = min_t(size_t, map.m_llen - (pos - map.m_la), count);
	DBG_BUGON(!count || count % PAGE_SIZE);

	mdev = (struct erofs_map_dev) {
		.m_deviceid = map.m_deviceid,
		.m_pa = map.m_pa,
	};
	ret = erofs_map_dev(sb, &mdev);
	if (ret)
		return ret;

	req = erofs_fscache_req_chain(primary, count);
	if (IS_ERR(req))
		return PTR_ERR(req);

	ret = erofs_fscache_read_folios_async(mdev.m_fscache->cookie,
			req, mdev.m_pa + (pos - map.m_la), count);
	erofs_fscache_req_put(req);
	primary->submitted += count;
	return ret;
}

static int erofs_fscache_data_read(struct erofs_fscache_request *req)
{
	int ret;

	do {
		ret = erofs_fscache_data_read_slice(req);
		if (ret)
			req->error = ret;
	} while (!ret && req->submitted < req->len);

	return ret;
}

static int erofs_fscache_read_folio(struct file *file, struct folio *folio)
{
	struct erofs_fscache_request *req;
	int ret;

	req = erofs_fscache_req_alloc(folio->mapping,
			folio_pos(folio), folio_size(folio));
	if (IS_ERR(req)) {
		folio_unlock(folio);
		return PTR_ERR(req);
	}

	ret = erofs_fscache_data_read(req);
	erofs_fscache_req_put(req);
	return ret;
}

static void erofs_fscache_readahead(struct readahead_control *rac)
{
	struct erofs_fscache_request *req;

	if (!readahead_count(rac))
		return;

	req = erofs_fscache_req_alloc(rac->mapping,
			readahead_pos(rac), readahead_length(rac));
	if (IS_ERR(req))
		return;

	/* The request completion will drop refs on the folios. */
	while (readahead_folio(rac))
		;

	erofs_fscache_data_read(req);
	erofs_fscache_req_put(req);
}

static const struct address_space_operations erofs_fscache_meta_aops = {
	.read_folio = erofs_fscache_meta_read_folio,
};

const struct address_space_operations erofs_fscache_access_aops = {
	.read_folio = erofs_fscache_read_folio,
	.readahead = erofs_fscache_readahead,
};

static void erofs_fscache_domain_put(struct erofs_domain *domain)
{
	mutex_lock(&erofs_domain_list_lock);
	if (refcount_dec_and_test(&domain->ref)) {
		list_del(&domain->list);
		if (list_empty(&erofs_domain_list)) {
			kern_unmount(erofs_pseudo_mnt);
			erofs_pseudo_mnt = NULL;
		}
		fscache_relinquish_volume(domain->volume, NULL, false);
		mutex_unlock(&erofs_domain_list_lock);
		kfree(domain->domain_id);
		kfree(domain);
		return;
	}
	mutex_unlock(&erofs_domain_list_lock);
}

static int erofs_fscache_register_volume(struct super_block *sb)
{
	struct erofs_sb_info *sbi = EROFS_SB(sb);
	char *domain_id = sbi->domain_id;
	struct fscache_volume *volume;
	char *name;
	int ret = 0;

	name = kasprintf(GFP_KERNEL, "erofs,%s",
			 domain_id ? domain_id : sbi->fsid);
	if (!name)
		return -ENOMEM;

	volume = fscache_acquire_volume(name, NULL, NULL, 0);
	if (IS_ERR_OR_NULL(volume)) {
		erofs_err(sb, "failed to register volume for %s", name);
		ret = volume ? PTR_ERR(volume) : -EOPNOTSUPP;
		volume = NULL;
	}

	sbi->volume = volume;
	kfree(name);
	return ret;
}

static int erofs_fscache_init_domain(struct super_block *sb)
{
	int err;
	struct erofs_domain *domain;
	struct erofs_sb_info *sbi = EROFS_SB(sb);

	domain = kzalloc(sizeof(struct erofs_domain), GFP_KERNEL);
	if (!domain)
		return -ENOMEM;

	domain->domain_id = kstrdup(sbi->domain_id, GFP_KERNEL);
	if (!domain->domain_id) {
		kfree(domain);
		return -ENOMEM;
	}

	err = erofs_fscache_register_volume(sb);
	if (err)
		goto out;

	if (!erofs_pseudo_mnt) {
		erofs_pseudo_mnt = kern_mount(&erofs_fs_type);
		if (IS_ERR(erofs_pseudo_mnt)) {
			err = PTR_ERR(erofs_pseudo_mnt);
			goto out;
		}
	}

	domain->volume = sbi->volume;
	refcount_set(&domain->ref, 1);
	list_add(&domain->list, &erofs_domain_list);
	sbi->domain = domain;
	return 0;
out:
	kfree(domain->domain_id);
	kfree(domain);
	return err;
}

static int erofs_fscache_register_domain(struct super_block *sb)
{
	int err;
	struct erofs_domain *domain;
	struct erofs_sb_info *sbi = EROFS_SB(sb);

	mutex_lock(&erofs_domain_list_lock);
	list_for_each_entry(domain, &erofs_domain_list, list) {
		if (!strcmp(domain->domain_id, sbi->domain_id)) {
			sbi->domain = domain;
			sbi->volume = domain->volume;
			refcount_inc(&domain->ref);
			mutex_unlock(&erofs_domain_list_lock);
			return 0;
		}
	}
	err = erofs_fscache_init_domain(sb);
	mutex_unlock(&erofs_domain_list_lock);
	return err;
}

static struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb,
						char *name, unsigned int flags)
{
	struct fscache_volume *volume = EROFS_SB(sb)->volume;
	struct erofs_fscache *ctx;
	struct fscache_cookie *cookie;
	struct super_block *isb;
	struct inode *inode;
	int ret;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
		return ERR_PTR(-ENOMEM);
	INIT_LIST_HEAD(&ctx->node);
	refcount_set(&ctx->ref, 1);

	cookie = fscache_acquire_cookie(volume, FSCACHE_ADV_WANT_CACHE_SIZE,
					name, strlen(name), NULL, 0, 0);
	if (!cookie) {
		erofs_err(sb, "failed to get cookie for %s", name);
		ret = -EINVAL;
		goto err;
	}
	fscache_use_cookie(cookie, false);

	/*
	 * Allocate anonymous inode in global pseudo mount for shareable blobs,
	 * so that they are accessible among erofs fs instances.
	 */
	isb = flags & EROFS_REG_COOKIE_SHARE ? erofs_pseudo_mnt->mnt_sb : sb;
	inode = new_inode(isb);
	if (!inode) {
		erofs_err(sb, "failed to get anon inode for %s", name);
		ret = -ENOMEM;
		goto err_cookie;
	}

	inode->i_size = OFFSET_MAX;
	inode->i_mapping->a_ops = &erofs_fscache_meta_aops;
	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
	inode->i_blkbits = EROFS_SB(sb)->blkszbits;
	inode->i_private = ctx;

	ctx->cookie = cookie;
	ctx->inode = inode;
	return ctx;

err_cookie:
	fscache_unuse_cookie(cookie, NULL, NULL);
	fscache_relinquish_cookie(cookie, false);
err:
	kfree(ctx);
	return ERR_PTR(ret);
}

static void erofs_fscache_relinquish_cookie(struct erofs_fscache *ctx)
{
	fscache_unuse_cookie(ctx->cookie, NULL, NULL);
	fscache_relinquish_cookie(ctx->cookie, false);
	iput(ctx->inode);
	kfree(ctx->name);
	kfree(ctx);
}

static struct erofs_fscache *erofs_domain_init_cookie(struct super_block *sb,
						char *name, unsigned int flags)
{
	struct erofs_fscache *ctx;
	struct erofs_domain *domain = EROFS_SB(sb)->domain;

	ctx = erofs_fscache_acquire_cookie(sb, name, flags);
	if (IS_ERR(ctx))
		return ctx;

	ctx->name = kstrdup(name, GFP_KERNEL);
	if (!ctx->name) {
		erofs_fscache_relinquish_cookie(ctx);
		return ERR_PTR(-ENOMEM);
	}

	refcount_inc(&domain->ref);
	ctx->domain = domain;
	list_add(&ctx->node, &erofs_domain_cookies_list);
	return ctx;
}

static struct erofs_fscache *erofs_domain_register_cookie(struct super_block *sb,
						char *name, unsigned int flags)
{
	struct erofs_fscache *ctx;
	struct erofs_domain *domain = EROFS_SB(sb)->domain;

	flags |= EROFS_REG_COOKIE_SHARE;
	mutex_lock(&erofs_domain_cookies_lock);
	list_for_each_entry(ctx, &erofs_domain_cookies_list, node) {
		if (ctx->domain != domain || strcmp(ctx->name, name))
			continue;
		if (!(flags & EROFS_REG_COOKIE_NEED_NOEXIST)) {
			refcount_inc(&ctx->ref);
		} else {
			erofs_err(sb, "%s already exists in domain %s", name,
				  domain->domain_id);
			ctx = ERR_PTR(-EEXIST);
		}
		mutex_unlock(&erofs_domain_cookies_lock);
		return ctx;
	}
	ctx = erofs_domain_init_cookie(sb, name, flags);
	mutex_unlock(&erofs_domain_cookies_lock);
	return ctx;
}

struct erofs_fscache *erofs_fscache_register_cookie(struct super_block *sb,
						    char *name,
						    unsigned int flags)
{
	if (EROFS_SB(sb)->domain_id)
		return erofs_domain_register_cookie(sb, name, flags);
	return erofs_fscache_acquire_cookie(sb, name, flags);
}

void erofs_fscache_unregister_cookie(struct erofs_fscache *ctx)
{
	struct erofs_domain *domain = NULL;

	if (!ctx)
		return;
	if (!ctx->domain)
		return erofs_fscache_relinquish_cookie(ctx);

	mutex_lock(&erofs_domain_cookies_lock);
	if (refcount_dec_and_test(&ctx->ref)) {
		domain = ctx->domain;
		list_del(&ctx->node);
		erofs_fscache_relinquish_cookie(ctx);
	}
	mutex_unlock(&erofs_domain_cookies_lock);
	if (domain)
		erofs_fscache_domain_put(domain);
}

int erofs_fscache_register_fs(struct super_block *sb)
{
	int ret;
	struct erofs_sb_info *sbi = EROFS_SB(sb);
	struct erofs_fscache *fscache;
	unsigned int flags = 0;

	if (sbi->domain_id)
		ret = erofs_fscache_register_domain(sb);
	else
		ret = erofs_fscache_register_volume(sb);
	if (ret)
		return ret;

	/*
	 * When shared domain is enabled, using NEED_NOEXIST to guarantee
	 * the primary data blob (aka fsid) is unique in the shared domain.
	 *
	 * For non-shared-domain case, fscache_acquire_volume() invoked by
	 * erofs_fscache_register_volume() has already guaranteed
	 * the uniqueness of primary data blob.
	 *
	 * Acquired domain/volume will be relinquished in kill_sb() on error.
	 */
	if (sbi->domain_id)
		flags |= EROFS_REG_COOKIE_NEED_NOEXIST;
	fscache = erofs_fscache_register_cookie(sb, sbi->fsid, flags);
	if (IS_ERR(fscache))
		return PTR_ERR(fscache);

	sbi->s_fscache = fscache;
	return 0;
}

void erofs_fscache_unregister_fs(struct super_block *sb)
{
	struct erofs_sb_info *sbi = EROFS_SB(sb);

	erofs_fscache_unregister_cookie(sbi->s_fscache);

	if (sbi->domain)
		erofs_fscache_domain_put(sbi->domain);
	else
		fscache_relinquish_volume(sbi->volume, NULL, false);

	sbi->s_fscache = NULL;
	sbi->volume = NULL;
	sbi->domain = NULL;
}