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1// SPDX-License-Identifier: GPL-2.0
2/*
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 *
10 * The ext4_mpage_readpages() function here is intended to
11 * replace mpage_readahead() in the general case, not just for
12 * 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:
27 * the end-of-file on blocksize < PAGE_SIZE setups.
28 *
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
50#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,
60 STEP_MAX,
61};
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)
71{
72 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);
110 struct bio *bio = ctx->bio;
111
112 /*
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;
122
123 fsverity_verify_bio(bio);
124
125 __read_end_io(bio);
126}
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++;
143 fallthrough;
144 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++;
151 fallthrough;
152 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;
160}
161
162/*
163 * 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 */
174static void mpage_end_io(struct bio *bio)
175{
176 if (bio_post_read_required(bio)) {
177 struct bio_post_read_ctx *ctx = bio->bi_private;
178
179 ctx->cur_step = STEP_INITIAL;
180 bio_post_read_processing(ctx);
181 return;
182 }
183 __read_end_io(bio);
184}
185
186static 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
192static void ext4_set_bio_post_read_ctx(struct bio *bio,
193 const struct inode *inode,
194 pgoff_t first_idx)
195{
196 unsigned int post_read_steps = 0;
197
198 if (fscrypt_inode_uses_fs_layer_crypto(inode))
199 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) {
205 /* 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
209 ctx->bio = bio;
210 ctx->enabled_steps = post_read_steps;
211 bio->bi_private = ctx;
212 }
213}
214
215static 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);
222}
223
224int ext4_mpage_readpages(struct inode *inode,
225 struct readahead_control *rac, struct page *page)
226{
227 struct bio *bio = NULL;
228 sector_t last_block_in_bio = 0;
229
230 const unsigned blkbits = inode->i_blkbits;
231 const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
232 const unsigned blocksize = 1 << blkbits;
233 sector_t next_block;
234 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;
243 unsigned int nr_pages = rac ? readahead_count(rac) : 1;
244
245 map.m_pblk = 0;
246 map.m_lblk = 0;
247 map.m_len = 0;
248 map.m_flags = 0;
249
250 for (; nr_pages; nr_pages--) {
251 int fully_mapped = 1;
252 unsigned first_hole = blocks_per_page;
253
254 if (rac) {
255 page = readahead_page(rac);
256 prefetchw(&page->flags);
257 }
258
259 if (page_has_buffers(page))
260 goto confused;
261
262 block_in_file = next_block =
263 (sector_t)page->index << (PAGE_SHIFT - blkbits);
264 last_block = block_in_file + nr_pages * blocks_per_page;
265 last_block_in_file = (ext4_readpage_limit(inode) +
266 blocksize - 1) >> blkbits;
267 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,
308 PAGE_SIZE);
309 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,
341 PAGE_SIZE);
342 if (first_hole == 0) {
343 if (ext4_need_verity(inode, page->index) &&
344 !fsverity_verify_page(page))
345 goto set_error_page;
346 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 */
363 if (bio && (last_block_in_bio != blocks[0] - 1 ||
364 !fscrypt_mergeable_bio(bio, inode, next_block))) {
365 submit_and_realloc:
366 submit_bio(bio);
367 bio = NULL;
368 }
369 if (bio == NULL) {
370 /*
371 * bio_alloc will _always_ be able to allocate a bio if
372 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
373 */
374 bio = bio_alloc(GFP_KERNEL,
375 min_t(int, nr_pages, BIO_MAX_PAGES));
376 fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
377 GFP_KERNEL);
378 ext4_set_bio_post_read_ctx(bio, inode, page->index);
379 bio_set_dev(bio, bdev);
380 bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
381 bio->bi_end_io = mpage_end_io;
382 bio_set_op_attrs(bio, REQ_OP_READ,
383 rac ? REQ_RAHEAD : 0);
384 }
385
386 length = first_hole << blkbits;
387 if (bio_add_page(bio, page, length, 0) < length)
388 goto submit_and_realloc;
389
390 if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
391 (relative_block == map.m_len)) ||
392 (first_hole != blocks_per_page)) {
393 submit_bio(bio);
394 bio = NULL;
395 } else
396 last_block_in_bio = blocks[blocks_per_page - 1];
397 goto next_page;
398 confused:
399 if (bio) {
400 submit_bio(bio);
401 bio = NULL;
402 }
403 if (!PageUptodate(page))
404 block_read_full_page(page, ext4_get_block);
405 else
406 unlock_page(page);
407 next_page:
408 if (rac)
409 put_page(page);
410 }
411 if (bio)
412 submit_bio(bio);
413 return 0;
414}
415
416int __init ext4_init_post_read_processing(void)
417{
418 bio_post_read_ctx_cache =
419 kmem_cache_create("ext4_bio_post_read_ctx",
420 sizeof(struct bio_post_read_ctx), 0, 0, NULL);
421 if (!bio_post_read_ctx_cache)
422 goto fail;
423 bio_post_read_ctx_pool =
424 mempool_create_slab_pool(NUM_PREALLOC_POST_READ_CTXS,
425 bio_post_read_ctx_cache);
426 if (!bio_post_read_ctx_pool)
427 goto fail_free_cache;
428 return 0;
429
430fail_free_cache:
431 kmem_cache_destroy(bio_post_read_ctx_cache);
432fail:
433 return -ENOMEM;
434}
435
436void ext4_exit_post_read_processing(void)
437{
438 mempool_destroy(bio_post_read_ctx_pool);
439 kmem_cache_destroy(bio_post_read_ctx_cache);
440}
1// SPDX-License-Identifier: GPL-2.0
2/*
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 *
10 * The ext4_mpage_readpages() function here is intended to
11 * replace mpage_readahead() in the general case, not just for
12 * 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:
27 * the end-of-file on blocksize < PAGE_SIZE setups.
28 *
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
47#include "ext4.h"
48
49#define NUM_PREALLOC_POST_READ_CTXS 128
50
51static struct kmem_cache *bio_post_read_ctx_cache;
52static mempool_t *bio_post_read_ctx_pool;
53
54/* postprocessing steps for read bios */
55enum bio_post_read_step {
56 STEP_INITIAL = 0,
57 STEP_DECRYPT,
58 STEP_VERITY,
59 STEP_MAX,
60};
61
62struct bio_post_read_ctx {
63 struct bio *bio;
64 struct work_struct work;
65 unsigned int cur_step;
66 unsigned int enabled_steps;
67};
68
69static void __read_end_io(struct bio *bio)
70{
71 struct folio_iter fi;
72
73 bio_for_each_folio_all(fi, bio)
74 folio_end_read(fi.folio, bio->bi_status == 0);
75 if (bio->bi_private)
76 mempool_free(bio->bi_private, bio_post_read_ctx_pool);
77 bio_put(bio);
78}
79
80static void bio_post_read_processing(struct bio_post_read_ctx *ctx);
81
82static void decrypt_work(struct work_struct *work)
83{
84 struct bio_post_read_ctx *ctx =
85 container_of(work, struct bio_post_read_ctx, work);
86 struct bio *bio = ctx->bio;
87
88 if (fscrypt_decrypt_bio(bio))
89 bio_post_read_processing(ctx);
90 else
91 __read_end_io(bio);
92}
93
94static void verity_work(struct work_struct *work)
95{
96 struct bio_post_read_ctx *ctx =
97 container_of(work, struct bio_post_read_ctx, work);
98 struct bio *bio = ctx->bio;
99
100 /*
101 * fsverity_verify_bio() may call readahead() again, and although verity
102 * will be disabled for that, decryption may still be needed, causing
103 * another bio_post_read_ctx to be allocated. So to guarantee that
104 * mempool_alloc() never deadlocks we must free the current ctx first.
105 * This is safe because verity is the last post-read step.
106 */
107 BUILD_BUG_ON(STEP_VERITY + 1 != STEP_MAX);
108 mempool_free(ctx, bio_post_read_ctx_pool);
109 bio->bi_private = NULL;
110
111 fsverity_verify_bio(bio);
112
113 __read_end_io(bio);
114}
115
116static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
117{
118 /*
119 * We use different work queues for decryption and for verity because
120 * verity may require reading metadata pages that need decryption, and
121 * we shouldn't recurse to the same workqueue.
122 */
123 switch (++ctx->cur_step) {
124 case STEP_DECRYPT:
125 if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {
126 INIT_WORK(&ctx->work, decrypt_work);
127 fscrypt_enqueue_decrypt_work(&ctx->work);
128 return;
129 }
130 ctx->cur_step++;
131 fallthrough;
132 case STEP_VERITY:
133 if (ctx->enabled_steps & (1 << STEP_VERITY)) {
134 INIT_WORK(&ctx->work, verity_work);
135 fsverity_enqueue_verify_work(&ctx->work);
136 return;
137 }
138 ctx->cur_step++;
139 fallthrough;
140 default:
141 __read_end_io(ctx->bio);
142 }
143}
144
145static bool bio_post_read_required(struct bio *bio)
146{
147 return bio->bi_private && !bio->bi_status;
148}
149
150/*
151 * I/O completion handler for multipage BIOs.
152 *
153 * The mpage code never puts partial pages into a BIO (except for end-of-file).
154 * If a page does not map to a contiguous run of blocks then it simply falls
155 * back to block_read_full_folio().
156 *
157 * Why is this? If a page's completion depends on a number of different BIOs
158 * which can complete in any order (or at the same time) then determining the
159 * status of that page is hard. See end_buffer_async_read() for the details.
160 * There is no point in duplicating all that complexity.
161 */
162static void mpage_end_io(struct bio *bio)
163{
164 if (bio_post_read_required(bio)) {
165 struct bio_post_read_ctx *ctx = bio->bi_private;
166
167 ctx->cur_step = STEP_INITIAL;
168 bio_post_read_processing(ctx);
169 return;
170 }
171 __read_end_io(bio);
172}
173
174static inline bool ext4_need_verity(const struct inode *inode, pgoff_t idx)
175{
176 return fsverity_active(inode) &&
177 idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
178}
179
180static void ext4_set_bio_post_read_ctx(struct bio *bio,
181 const struct inode *inode,
182 pgoff_t first_idx)
183{
184 unsigned int post_read_steps = 0;
185
186 if (fscrypt_inode_uses_fs_layer_crypto(inode))
187 post_read_steps |= 1 << STEP_DECRYPT;
188
189 if (ext4_need_verity(inode, first_idx))
190 post_read_steps |= 1 << STEP_VERITY;
191
192 if (post_read_steps) {
193 /* Due to the mempool, this never fails. */
194 struct bio_post_read_ctx *ctx =
195 mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
196
197 ctx->bio = bio;
198 ctx->enabled_steps = post_read_steps;
199 bio->bi_private = ctx;
200 }
201}
202
203static inline loff_t ext4_readpage_limit(struct inode *inode)
204{
205 if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
206 return inode->i_sb->s_maxbytes;
207
208 return i_size_read(inode);
209}
210
211int ext4_mpage_readpages(struct inode *inode,
212 struct readahead_control *rac, struct folio *folio)
213{
214 struct bio *bio = NULL;
215 sector_t last_block_in_bio = 0;
216
217 const unsigned blkbits = inode->i_blkbits;
218 const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
219 const unsigned blocksize = 1 << blkbits;
220 sector_t next_block;
221 sector_t block_in_file;
222 sector_t last_block;
223 sector_t last_block_in_file;
224 sector_t blocks[MAX_BUF_PER_PAGE];
225 unsigned page_block;
226 struct block_device *bdev = inode->i_sb->s_bdev;
227 int length;
228 unsigned relative_block = 0;
229 struct ext4_map_blocks map;
230 unsigned int nr_pages = rac ? readahead_count(rac) : 1;
231
232 map.m_pblk = 0;
233 map.m_lblk = 0;
234 map.m_len = 0;
235 map.m_flags = 0;
236
237 for (; nr_pages; nr_pages--) {
238 int fully_mapped = 1;
239 unsigned first_hole = blocks_per_page;
240
241 if (rac)
242 folio = readahead_folio(rac);
243 prefetchw(&folio->flags);
244
245 if (folio_buffers(folio))
246 goto confused;
247
248 block_in_file = next_block =
249 (sector_t)folio->index << (PAGE_SHIFT - blkbits);
250 last_block = block_in_file + nr_pages * blocks_per_page;
251 last_block_in_file = (ext4_readpage_limit(inode) +
252 blocksize - 1) >> blkbits;
253 if (last_block > last_block_in_file)
254 last_block = last_block_in_file;
255 page_block = 0;
256
257 /*
258 * Map blocks using the previous result first.
259 */
260 if ((map.m_flags & EXT4_MAP_MAPPED) &&
261 block_in_file > map.m_lblk &&
262 block_in_file < (map.m_lblk + map.m_len)) {
263 unsigned map_offset = block_in_file - map.m_lblk;
264 unsigned last = map.m_len - map_offset;
265
266 for (relative_block = 0; ; relative_block++) {
267 if (relative_block == last) {
268 /* needed? */
269 map.m_flags &= ~EXT4_MAP_MAPPED;
270 break;
271 }
272 if (page_block == blocks_per_page)
273 break;
274 blocks[page_block] = map.m_pblk + map_offset +
275 relative_block;
276 page_block++;
277 block_in_file++;
278 }
279 }
280
281 /*
282 * Then do more ext4_map_blocks() calls until we are
283 * done with this folio.
284 */
285 while (page_block < blocks_per_page) {
286 if (block_in_file < last_block) {
287 map.m_lblk = block_in_file;
288 map.m_len = last_block - block_in_file;
289
290 if (ext4_map_blocks(NULL, inode, &map, 0) < 0) {
291 set_error_page:
292 folio_set_error(folio);
293 folio_zero_segment(folio, 0,
294 folio_size(folio));
295 folio_unlock(folio);
296 goto next_page;
297 }
298 }
299 if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {
300 fully_mapped = 0;
301 if (first_hole == blocks_per_page)
302 first_hole = page_block;
303 page_block++;
304 block_in_file++;
305 continue;
306 }
307 if (first_hole != blocks_per_page)
308 goto confused; /* hole -> non-hole */
309
310 /* Contiguous blocks? */
311 if (page_block && blocks[page_block-1] != map.m_pblk-1)
312 goto confused;
313 for (relative_block = 0; ; relative_block++) {
314 if (relative_block == map.m_len) {
315 /* needed? */
316 map.m_flags &= ~EXT4_MAP_MAPPED;
317 break;
318 } else if (page_block == blocks_per_page)
319 break;
320 blocks[page_block] = map.m_pblk+relative_block;
321 page_block++;
322 block_in_file++;
323 }
324 }
325 if (first_hole != blocks_per_page) {
326 folio_zero_segment(folio, first_hole << blkbits,
327 folio_size(folio));
328 if (first_hole == 0) {
329 if (ext4_need_verity(inode, folio->index) &&
330 !fsverity_verify_folio(folio))
331 goto set_error_page;
332 folio_end_read(folio, true);
333 continue;
334 }
335 } else if (fully_mapped) {
336 folio_set_mappedtodisk(folio);
337 }
338
339 /*
340 * This folio will go to BIO. Do we need to send this
341 * BIO off first?
342 */
343 if (bio && (last_block_in_bio != blocks[0] - 1 ||
344 !fscrypt_mergeable_bio(bio, inode, next_block))) {
345 submit_and_realloc:
346 submit_bio(bio);
347 bio = NULL;
348 }
349 if (bio == NULL) {
350 /*
351 * bio_alloc will _always_ be able to allocate a bio if
352 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
353 */
354 bio = bio_alloc(bdev, bio_max_segs(nr_pages),
355 REQ_OP_READ, GFP_KERNEL);
356 fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
357 GFP_KERNEL);
358 ext4_set_bio_post_read_ctx(bio, inode, folio->index);
359 bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
360 bio->bi_end_io = mpage_end_io;
361 if (rac)
362 bio->bi_opf |= REQ_RAHEAD;
363 }
364
365 length = first_hole << blkbits;
366 if (!bio_add_folio(bio, folio, length, 0))
367 goto submit_and_realloc;
368
369 if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
370 (relative_block == map.m_len)) ||
371 (first_hole != blocks_per_page)) {
372 submit_bio(bio);
373 bio = NULL;
374 } else
375 last_block_in_bio = blocks[blocks_per_page - 1];
376 continue;
377 confused:
378 if (bio) {
379 submit_bio(bio);
380 bio = NULL;
381 }
382 if (!folio_test_uptodate(folio))
383 block_read_full_folio(folio, ext4_get_block);
384 else
385 folio_unlock(folio);
386next_page:
387 ; /* A label shall be followed by a statement until C23 */
388 }
389 if (bio)
390 submit_bio(bio);
391 return 0;
392}
393
394int __init ext4_init_post_read_processing(void)
395{
396 bio_post_read_ctx_cache = KMEM_CACHE(bio_post_read_ctx, SLAB_RECLAIM_ACCOUNT);
397
398 if (!bio_post_read_ctx_cache)
399 goto fail;
400 bio_post_read_ctx_pool =
401 mempool_create_slab_pool(NUM_PREALLOC_POST_READ_CTXS,
402 bio_post_read_ctx_cache);
403 if (!bio_post_read_ctx_pool)
404 goto fail_free_cache;
405 return 0;
406
407fail_free_cache:
408 kmem_cache_destroy(bio_post_read_ctx_cache);
409fail:
410 return -ENOMEM;
411}
412
413void ext4_exit_post_read_processing(void)
414{
415 mempool_destroy(bio_post_read_ctx_pool);
416 kmem_cache_destroy(bio_post_read_ctx_cache);
417}