blob: 3db9234035053ed976030abc2152acf9c3aac84a [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Theodore Ts'of64e02f2015-04-08 00:00:32 -04002/*
3 * linux/fs/ext4/readpage.c
4 *
5 * Copyright (C) 2002, Linus Torvalds.
6 * Copyright (C) 2015, Google, Inc.
7 *
8 * This was originally taken from fs/mpage.c
9 *
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -070010 * The ext4_mpage_readpages() function here is intended to
11 * replace mpage_readahead() in the general case, not just for
Theodore Ts'of64e02f2015-04-08 00:00:32 -040012 * encrypted files. It has some limitations (see below), where it
13 * will fall back to read_block_full_page(), but these limitations
14 * should only be hit when page_size != block_size.
15 *
16 * This will allow us to attach a callback function to support ext4
17 * encryption.
18 *
19 * If anything unusual happens, such as:
20 *
21 * - encountering a page which has buffers
22 * - encountering a page which has a non-hole after a hole
23 * - encountering a page with non-contiguous blocks
24 *
25 * then this code just gives up and calls the buffer_head-based read function.
26 * It does handle a page which has holes at the end - that is a common case:
Kirill A. Shutemovea1754a2016-04-01 15:29:48 +030027 * the end-of-file on blocksize < PAGE_SIZE setups.
Theodore Ts'of64e02f2015-04-08 00:00:32 -040028 *
29 */
30
31#include <linux/kernel.h>
32#include <linux/export.h>
33#include <linux/mm.h>
34#include <linux/kdev_t.h>
35#include <linux/gfp.h>
36#include <linux/bio.h>
37#include <linux/fs.h>
38#include <linux/buffer_head.h>
39#include <linux/blkdev.h>
40#include <linux/highmem.h>
41#include <linux/prefetch.h>
42#include <linux/mpage.h>
43#include <linux/writeback.h>
44#include <linux/backing-dev.h>
45#include <linux/pagevec.h>
46#include <linux/cleancache.h>
47
48#include "ext4.h"
49
Eric Biggers22cfe4b2019-07-22 09:26:24 -070050#define NUM_PREALLOC_POST_READ_CTXS 128
51
52static struct kmem_cache *bio_post_read_ctx_cache;
53static mempool_t *bio_post_read_ctx_pool;
54
55/* postprocessing steps for read bios */
56enum bio_post_read_step {
57 STEP_INITIAL = 0,
58 STEP_DECRYPT,
59 STEP_VERITY,
Eric Biggers68e45332019-12-31 12:12:22 -060060 STEP_MAX,
Eric Biggers22cfe4b2019-07-22 09:26:24 -070061};
62
63struct bio_post_read_ctx {
64 struct bio *bio;
65 struct work_struct work;
66 unsigned int cur_step;
67 unsigned int enabled_steps;
68};
69
70static void __read_end_io(struct bio *bio)
Michael Halcrowc9c74292015-04-12 00:56:10 -040071{
Eric Biggers22cfe4b2019-07-22 09:26:24 -070072 struct page *page;
73 struct bio_vec *bv;
74 struct bvec_iter_all iter_all;
75
76 bio_for_each_segment_all(bv, bio, iter_all) {
77 page = bv->bv_page;
78
79 /* PG_error was set if any post_read step failed */
80 if (bio->bi_status || PageError(page)) {
81 ClearPageUptodate(page);
82 /* will re-read again later */
83 ClearPageError(page);
84 } else {
85 SetPageUptodate(page);
86 }
87 unlock_page(page);
88 }
89 if (bio->bi_private)
90 mempool_free(bio->bi_private, bio_post_read_ctx_pool);
91 bio_put(bio);
92}
93
94static void bio_post_read_processing(struct bio_post_read_ctx *ctx);
95
96static void decrypt_work(struct work_struct *work)
97{
98 struct bio_post_read_ctx *ctx =
99 container_of(work, struct bio_post_read_ctx, work);
100
101 fscrypt_decrypt_bio(ctx->bio);
102
103 bio_post_read_processing(ctx);
104}
105
106static void verity_work(struct work_struct *work)
107{
108 struct bio_post_read_ctx *ctx =
109 container_of(work, struct bio_post_read_ctx, work);
Eric Biggers68e45332019-12-31 12:12:22 -0600110 struct bio *bio = ctx->bio;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700111
Eric Biggers68e45332019-12-31 12:12:22 -0600112 /*
113 * fsverity_verify_bio() may call readpages() again, and although verity
114 * will be disabled for that, decryption may still be needed, causing
115 * another bio_post_read_ctx to be allocated. So to guarantee that
116 * mempool_alloc() never deadlocks we must free the current ctx first.
117 * This is safe because verity is the last post-read step.
118 */
119 BUILD_BUG_ON(STEP_VERITY + 1 != STEP_MAX);
120 mempool_free(ctx, bio_post_read_ctx_pool);
121 bio->bi_private = NULL;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700122
Eric Biggers68e45332019-12-31 12:12:22 -0600123 fsverity_verify_bio(bio);
124
125 __read_end_io(bio);
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700126}
127
128static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
129{
130 /*
131 * We use different work queues for decryption and for verity because
132 * verity may require reading metadata pages that need decryption, and
133 * we shouldn't recurse to the same workqueue.
134 */
135 switch (++ctx->cur_step) {
136 case STEP_DECRYPT:
137 if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {
138 INIT_WORK(&ctx->work, decrypt_work);
139 fscrypt_enqueue_decrypt_work(&ctx->work);
140 return;
141 }
142 ctx->cur_step++;
Shijie Luo70d7ced2020-08-10 07:44:35 -0400143 fallthrough;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700144 case STEP_VERITY:
145 if (ctx->enabled_steps & (1 << STEP_VERITY)) {
146 INIT_WORK(&ctx->work, verity_work);
147 fsverity_enqueue_verify_work(&ctx->work);
148 return;
149 }
150 ctx->cur_step++;
Shijie Luo70d7ced2020-08-10 07:44:35 -0400151 fallthrough;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700152 default:
153 __read_end_io(ctx->bio);
154 }
155}
156
157static bool bio_post_read_required(struct bio *bio)
158{
159 return bio->bi_private && !bio->bi_status;
Michael Halcrowc9c74292015-04-12 00:56:10 -0400160}
161
162/*
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400163 * I/O completion handler for multipage BIOs.
164 *
165 * The mpage code never puts partial pages into a BIO (except for end-of-file).
166 * If a page does not map to a contiguous run of blocks then it simply falls
167 * back to block_read_full_page().
168 *
169 * Why is this? If a page's completion depends on a number of different BIOs
170 * which can complete in any order (or at the same time) then determining the
171 * status of that page is hard. See end_buffer_async_read() for the details.
172 * There is no point in duplicating all that complexity.
173 */
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200174static void mpage_end_io(struct bio *bio)
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400175{
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700176 if (bio_post_read_required(bio)) {
177 struct bio_post_read_ctx *ctx = bio->bi_private;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400178
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700179 ctx->cur_step = STEP_INITIAL;
180 bio_post_read_processing(ctx);
181 return;
Michael Halcrowc9c74292015-04-12 00:56:10 -0400182 }
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700183 __read_end_io(bio);
184}
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400185
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700186static inline bool ext4_need_verity(const struct inode *inode, pgoff_t idx)
187{
188 return fsverity_active(inode) &&
189 idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
190}
191
Eric Biggersfd5fe252019-12-31 12:12:56 -0600192static void ext4_set_bio_post_read_ctx(struct bio *bio,
193 const struct inode *inode,
194 pgoff_t first_idx)
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700195{
196 unsigned int post_read_steps = 0;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700197
Eric Biggers4f74d152020-07-02 01:56:07 +0000198 if (fscrypt_inode_uses_fs_layer_crypto(inode))
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700199 post_read_steps |= 1 << STEP_DECRYPT;
200
201 if (ext4_need_verity(inode, first_idx))
202 post_read_steps |= 1 << STEP_VERITY;
203
204 if (post_read_steps) {
Eric Biggersfd5fe252019-12-31 12:12:56 -0600205 /* Due to the mempool, this never fails. */
206 struct bio_post_read_ctx *ctx =
207 mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
208
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700209 ctx->bio = bio;
210 ctx->enabled_steps = post_read_steps;
211 bio->bi_private = ctx;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400212 }
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700213}
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400214
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700215static inline loff_t ext4_readpage_limit(struct inode *inode)
216{
217 if (IS_ENABLED(CONFIG_FS_VERITY) &&
218 (IS_VERITY(inode) || ext4_verity_in_progress(inode)))
219 return inode->i_sb->s_maxbytes;
220
221 return i_size_read(inode);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400222}
223
Matthew Wilcox (Oracle)a07f6242020-06-01 21:47:20 -0700224int ext4_mpage_readpages(struct inode *inode,
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -0700225 struct readahead_control *rac, struct page *page)
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400226{
227 struct bio *bio = NULL;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400228 sector_t last_block_in_bio = 0;
229
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400230 const unsigned blkbits = inode->i_blkbits;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300231 const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400232 const unsigned blocksize = 1 << blkbits;
Eric Biggers4f74d152020-07-02 01:56:07 +0000233 sector_t next_block;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400234 sector_t block_in_file;
235 sector_t last_block;
236 sector_t last_block_in_file;
237 sector_t blocks[MAX_BUF_PER_PAGE];
238 unsigned page_block;
239 struct block_device *bdev = inode->i_sb->s_bdev;
240 int length;
241 unsigned relative_block = 0;
242 struct ext4_map_blocks map;
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -0700243 unsigned int nr_pages = rac ? readahead_count(rac) : 1;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400244
245 map.m_pblk = 0;
246 map.m_lblk = 0;
247 map.m_len = 0;
248 map.m_flags = 0;
249
yalin wangde9e9182016-07-05 16:32:32 -0400250 for (; nr_pages; nr_pages--) {
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400251 int fully_mapped = 1;
252 unsigned first_hole = blocks_per_page;
253
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -0700254 if (rac) {
255 page = readahead_page(rac);
Liu Xiangd454a272019-04-07 11:54:27 -0400256 prefetchw(&page->flags);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400257 }
258
259 if (page_has_buffers(page))
260 goto confused;
261
Eric Biggers4f74d152020-07-02 01:56:07 +0000262 block_in_file = next_block =
263 (sector_t)page->index << (PAGE_SHIFT - blkbits);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400264 last_block = block_in_file + nr_pages * blocks_per_page;
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700265 last_block_in_file = (ext4_readpage_limit(inode) +
266 blocksize - 1) >> blkbits;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400267 if (last_block > last_block_in_file)
268 last_block = last_block_in_file;
269 page_block = 0;
270
271 /*
272 * Map blocks using the previous result first.
273 */
274 if ((map.m_flags & EXT4_MAP_MAPPED) &&
275 block_in_file > map.m_lblk &&
276 block_in_file < (map.m_lblk + map.m_len)) {
277 unsigned map_offset = block_in_file - map.m_lblk;
278 unsigned last = map.m_len - map_offset;
279
280 for (relative_block = 0; ; relative_block++) {
281 if (relative_block == last) {
282 /* needed? */
283 map.m_flags &= ~EXT4_MAP_MAPPED;
284 break;
285 }
286 if (page_block == blocks_per_page)
287 break;
288 blocks[page_block] = map.m_pblk + map_offset +
289 relative_block;
290 page_block++;
291 block_in_file++;
292 }
293 }
294
295 /*
296 * Then do more ext4_map_blocks() calls until we are
297 * done with this page.
298 */
299 while (page_block < blocks_per_page) {
300 if (block_in_file < last_block) {
301 map.m_lblk = block_in_file;
302 map.m_len = last_block - block_in_file;
303
304 if (ext4_map_blocks(NULL, inode, &map, 0) < 0) {
305 set_error_page:
306 SetPageError(page);
307 zero_user_segment(page, 0,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300308 PAGE_SIZE);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400309 unlock_page(page);
310 goto next_page;
311 }
312 }
313 if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {
314 fully_mapped = 0;
315 if (first_hole == blocks_per_page)
316 first_hole = page_block;
317 page_block++;
318 block_in_file++;
319 continue;
320 }
321 if (first_hole != blocks_per_page)
322 goto confused; /* hole -> non-hole */
323
324 /* Contiguous blocks? */
325 if (page_block && blocks[page_block-1] != map.m_pblk-1)
326 goto confused;
327 for (relative_block = 0; ; relative_block++) {
328 if (relative_block == map.m_len) {
329 /* needed? */
330 map.m_flags &= ~EXT4_MAP_MAPPED;
331 break;
332 } else if (page_block == blocks_per_page)
333 break;
334 blocks[page_block] = map.m_pblk+relative_block;
335 page_block++;
336 block_in_file++;
337 }
338 }
339 if (first_hole != blocks_per_page) {
340 zero_user_segment(page, first_hole << blkbits,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300341 PAGE_SIZE);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400342 if (first_hole == 0) {
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700343 if (ext4_need_verity(inode, page->index) &&
344 !fsverity_verify_page(page))
345 goto set_error_page;
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400346 SetPageUptodate(page);
347 unlock_page(page);
348 goto next_page;
349 }
350 } else if (fully_mapped) {
351 SetPageMappedToDisk(page);
352 }
353 if (fully_mapped && blocks_per_page == 1 &&
354 !PageUptodate(page) && cleancache_get_page(page) == 0) {
355 SetPageUptodate(page);
356 goto confused;
357 }
358
359 /*
360 * This page will go to BIO. Do we need to send this
361 * BIO off first?
362 */
Eric Biggers4f74d152020-07-02 01:56:07 +0000363 if (bio && (last_block_in_bio != blocks[0] - 1 ||
364 !fscrypt_mergeable_bio(bio, inode, next_block))) {
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400365 submit_and_realloc:
Mike Christie4e49ea42016-06-05 14:31:41 -0500366 submit_bio(bio);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400367 bio = NULL;
368 }
369 if (bio == NULL) {
Gao Xiang55002212019-10-31 17:23:15 +0800370 /*
371 * bio_alloc will _always_ be able to allocate a bio if
372 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
373 */
Matthew Wilcox (Oracle)5f7136d2021-01-29 04:38:57 +0000374 bio = bio_alloc(GFP_KERNEL, bio_max_segs(nr_pages));
Eric Biggers4f74d152020-07-02 01:56:07 +0000375 fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
376 GFP_KERNEL);
Eric Biggersfd5fe252019-12-31 12:12:56 -0600377 ext4_set_bio_post_read_ctx(bio, inode, page->index);
Christoph Hellwig74d46992017-08-23 19:10:32 +0200378 bio_set_dev(bio, bdev);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400379 bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
380 bio->bi_end_io = mpage_end_io;
Jens Axboeac22b462018-08-17 15:45:42 -0700381 bio_set_op_attrs(bio, REQ_OP_READ,
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -0700382 rac ? REQ_RAHEAD : 0);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400383 }
384
385 length = first_hole << blkbits;
386 if (bio_add_page(bio, page, length, 0) < length)
387 goto submit_and_realloc;
388
389 if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
390 (relative_block == map.m_len)) ||
391 (first_hole != blocks_per_page)) {
Mike Christie4e49ea42016-06-05 14:31:41 -0500392 submit_bio(bio);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400393 bio = NULL;
394 } else
395 last_block_in_bio = blocks[blocks_per_page - 1];
396 goto next_page;
397 confused:
398 if (bio) {
Mike Christie4e49ea42016-06-05 14:31:41 -0500399 submit_bio(bio);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400400 bio = NULL;
401 }
402 if (!PageUptodate(page))
403 block_read_full_page(page, ext4_get_block);
404 else
405 unlock_page(page);
406 next_page:
Matthew Wilcox (Oracle)6311f91f2020-06-01 21:47:16 -0700407 if (rac)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300408 put_page(page);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400409 }
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400410 if (bio)
Mike Christie4e49ea42016-06-05 14:31:41 -0500411 submit_bio(bio);
Theodore Ts'of64e02f2015-04-08 00:00:32 -0400412 return 0;
413}
Eric Biggers22cfe4b2019-07-22 09:26:24 -0700414
415int __init ext4_init_post_read_processing(void)
416{
417 bio_post_read_ctx_cache =
418 kmem_cache_create("ext4_bio_post_read_ctx",
419 sizeof(struct bio_post_read_ctx), 0, 0, NULL);
420 if (!bio_post_read_ctx_cache)
421 goto fail;
422 bio_post_read_ctx_pool =
423 mempool_create_slab_pool(NUM_PREALLOC_POST_READ_CTXS,
424 bio_post_read_ctx_cache);
425 if (!bio_post_read_ctx_pool)
426 goto fail_free_cache;
427 return 0;
428
429fail_free_cache:
430 kmem_cache_destroy(bio_post_read_ctx_cache);
431fail:
432 return -ENOMEM;
433}
434
435void ext4_exit_post_read_processing(void)
436{
437 mempool_destroy(bio_post_read_ctx_pool);
438 kmem_cache_destroy(bio_post_read_ctx_cache);
439}