net: dsa: mt7530: enable MTU normalization
[linux-2.6-microblaze.git] / mm / page_io.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/mm/page_io.c
4  *
5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
6  *
7  *  Swap reorganised 29.12.95, 
8  *  Asynchronous swapping added 30.12.95. Stephen Tweedie
9  *  Removed race in async swapping. 14.4.1996. Bruno Haible
10  *  Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
11  *  Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
12  */
13
14 #include <linux/mm.h>
15 #include <linux/kernel_stat.h>
16 #include <linux/gfp.h>
17 #include <linux/pagemap.h>
18 #include <linux/swap.h>
19 #include <linux/bio.h>
20 #include <linux/swapops.h>
21 #include <linux/buffer_head.h>
22 #include <linux/writeback.h>
23 #include <linux/frontswap.h>
24 #include <linux/blkdev.h>
25 #include <linux/psi.h>
26 #include <linux/uio.h>
27 #include <linux/sched/task.h>
28
29 static struct bio *get_swap_bio(gfp_t gfp_flags,
30                                 struct page *page, bio_end_io_t end_io)
31 {
32         struct bio *bio;
33
34         bio = bio_alloc(gfp_flags, 1);
35         if (bio) {
36                 struct block_device *bdev;
37
38                 bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
39                 bio_set_dev(bio, bdev);
40                 bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
41                 bio->bi_end_io = end_io;
42
43                 bio_add_page(bio, page, thp_size(page), 0);
44         }
45         return bio;
46 }
47
48 void end_swap_bio_write(struct bio *bio)
49 {
50         struct page *page = bio_first_page_all(bio);
51
52         if (bio->bi_status) {
53                 SetPageError(page);
54                 /*
55                  * We failed to write the page out to swap-space.
56                  * Re-dirty the page in order to avoid it being reclaimed.
57                  * Also print a dire warning that things will go BAD (tm)
58                  * very quickly.
59                  *
60                  * Also clear PG_reclaim to avoid rotate_reclaimable_page()
61                  */
62                 set_page_dirty(page);
63                 pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
64                          MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
65                          (unsigned long long)bio->bi_iter.bi_sector);
66                 ClearPageReclaim(page);
67         }
68         end_page_writeback(page);
69         bio_put(bio);
70 }
71
72 static void swap_slot_free_notify(struct page *page)
73 {
74         struct swap_info_struct *sis;
75         struct gendisk *disk;
76         swp_entry_t entry;
77
78         /*
79          * There is no guarantee that the page is in swap cache - the software
80          * suspend code (at least) uses end_swap_bio_read() against a non-
81          * swapcache page.  So we must check PG_swapcache before proceeding with
82          * this optimization.
83          */
84         if (unlikely(!PageSwapCache(page)))
85                 return;
86
87         sis = page_swap_info(page);
88         if (data_race(!(sis->flags & SWP_BLKDEV)))
89                 return;
90
91         /*
92          * The swap subsystem performs lazy swap slot freeing,
93          * expecting that the page will be swapped out again.
94          * So we can avoid an unnecessary write if the page
95          * isn't redirtied.
96          * This is good for real swap storage because we can
97          * reduce unnecessary I/O and enhance wear-leveling
98          * if an SSD is used as the as swap device.
99          * But if in-memory swap device (eg zram) is used,
100          * this causes a duplicated copy between uncompressed
101          * data in VM-owned memory and compressed data in
102          * zram-owned memory.  So let's free zram-owned memory
103          * and make the VM-owned decompressed page *dirty*,
104          * so the page should be swapped out somewhere again if
105          * we again wish to reclaim it.
106          */
107         disk = sis->bdev->bd_disk;
108         entry.val = page_private(page);
109         if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
110                 unsigned long offset;
111
112                 offset = swp_offset(entry);
113
114                 SetPageDirty(page);
115                 disk->fops->swap_slot_free_notify(sis->bdev,
116                                 offset);
117         }
118 }
119
120 static void end_swap_bio_read(struct bio *bio)
121 {
122         struct page *page = bio_first_page_all(bio);
123         struct task_struct *waiter = bio->bi_private;
124
125         if (bio->bi_status) {
126                 SetPageError(page);
127                 ClearPageUptodate(page);
128                 pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
129                          MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
130                          (unsigned long long)bio->bi_iter.bi_sector);
131                 goto out;
132         }
133
134         SetPageUptodate(page);
135         swap_slot_free_notify(page);
136 out:
137         unlock_page(page);
138         WRITE_ONCE(bio->bi_private, NULL);
139         bio_put(bio);
140         if (waiter) {
141                 blk_wake_io_task(waiter);
142                 put_task_struct(waiter);
143         }
144 }
145
146 int generic_swapfile_activate(struct swap_info_struct *sis,
147                                 struct file *swap_file,
148                                 sector_t *span)
149 {
150         struct address_space *mapping = swap_file->f_mapping;
151         struct inode *inode = mapping->host;
152         unsigned blocks_per_page;
153         unsigned long page_no;
154         unsigned blkbits;
155         sector_t probe_block;
156         sector_t last_block;
157         sector_t lowest_block = -1;
158         sector_t highest_block = 0;
159         int nr_extents = 0;
160         int ret;
161
162         blkbits = inode->i_blkbits;
163         blocks_per_page = PAGE_SIZE >> blkbits;
164
165         /*
166          * Map all the blocks into the extent tree.  This code doesn't try
167          * to be very smart.
168          */
169         probe_block = 0;
170         page_no = 0;
171         last_block = i_size_read(inode) >> blkbits;
172         while ((probe_block + blocks_per_page) <= last_block &&
173                         page_no < sis->max) {
174                 unsigned block_in_page;
175                 sector_t first_block;
176
177                 cond_resched();
178
179                 first_block = probe_block;
180                 ret = bmap(inode, &first_block);
181                 if (ret || !first_block)
182                         goto bad_bmap;
183
184                 /*
185                  * It must be PAGE_SIZE aligned on-disk
186                  */
187                 if (first_block & (blocks_per_page - 1)) {
188                         probe_block++;
189                         goto reprobe;
190                 }
191
192                 for (block_in_page = 1; block_in_page < blocks_per_page;
193                                         block_in_page++) {
194                         sector_t block;
195
196                         block = probe_block + block_in_page;
197                         ret = bmap(inode, &block);
198                         if (ret || !block)
199                                 goto bad_bmap;
200
201                         if (block != first_block + block_in_page) {
202                                 /* Discontiguity */
203                                 probe_block++;
204                                 goto reprobe;
205                         }
206                 }
207
208                 first_block >>= (PAGE_SHIFT - blkbits);
209                 if (page_no) {  /* exclude the header page */
210                         if (first_block < lowest_block)
211                                 lowest_block = first_block;
212                         if (first_block > highest_block)
213                                 highest_block = first_block;
214                 }
215
216                 /*
217                  * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
218                  */
219                 ret = add_swap_extent(sis, page_no, 1, first_block);
220                 if (ret < 0)
221                         goto out;
222                 nr_extents += ret;
223                 page_no++;
224                 probe_block += blocks_per_page;
225 reprobe:
226                 continue;
227         }
228         ret = nr_extents;
229         *span = 1 + highest_block - lowest_block;
230         if (page_no == 0)
231                 page_no = 1;    /* force Empty message */
232         sis->max = page_no;
233         sis->pages = page_no - 1;
234         sis->highest_bit = page_no - 1;
235 out:
236         return ret;
237 bad_bmap:
238         pr_err("swapon: swapfile has holes\n");
239         ret = -EINVAL;
240         goto out;
241 }
242
243 /*
244  * We may have stale swap cache pages in memory: notice
245  * them here and get rid of the unnecessary final write.
246  */
247 int swap_writepage(struct page *page, struct writeback_control *wbc)
248 {
249         int ret = 0;
250
251         if (try_to_free_swap(page)) {
252                 unlock_page(page);
253                 goto out;
254         }
255         /*
256          * Arch code may have to preserve more data than just the page
257          * contents, e.g. memory tags.
258          */
259         ret = arch_prepare_to_swap(page);
260         if (ret) {
261                 set_page_dirty(page);
262                 unlock_page(page);
263                 goto out;
264         }
265         if (frontswap_store(page) == 0) {
266                 set_page_writeback(page);
267                 unlock_page(page);
268                 end_page_writeback(page);
269                 goto out;
270         }
271         ret = __swap_writepage(page, wbc, end_swap_bio_write);
272 out:
273         return ret;
274 }
275
276 static sector_t swap_page_sector(struct page *page)
277 {
278         return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
279 }
280
281 static inline void count_swpout_vm_event(struct page *page)
282 {
283 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
284         if (unlikely(PageTransHuge(page)))
285                 count_vm_event(THP_SWPOUT);
286 #endif
287         count_vm_events(PSWPOUT, thp_nr_pages(page));
288 }
289
290 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
291 static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
292 {
293         struct cgroup_subsys_state *css;
294         struct mem_cgroup *memcg;
295
296         memcg = page_memcg(page);
297         if (!memcg)
298                 return;
299
300         rcu_read_lock();
301         css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
302         bio_associate_blkg_from_css(bio, css);
303         rcu_read_unlock();
304 }
305 #else
306 #define bio_associate_blkg_from_page(bio, page)         do { } while (0)
307 #endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
308
309 int __swap_writepage(struct page *page, struct writeback_control *wbc,
310                 bio_end_io_t end_write_func)
311 {
312         struct bio *bio;
313         int ret;
314         struct swap_info_struct *sis = page_swap_info(page);
315
316         VM_BUG_ON_PAGE(!PageSwapCache(page), page);
317         if (data_race(sis->flags & SWP_FS_OPS)) {
318                 struct kiocb kiocb;
319                 struct file *swap_file = sis->swap_file;
320                 struct address_space *mapping = swap_file->f_mapping;
321                 struct bio_vec bv = {
322                         .bv_page = page,
323                         .bv_len  = PAGE_SIZE,
324                         .bv_offset = 0
325                 };
326                 struct iov_iter from;
327
328                 iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE);
329                 init_sync_kiocb(&kiocb, swap_file);
330                 kiocb.ki_pos = page_file_offset(page);
331
332                 set_page_writeback(page);
333                 unlock_page(page);
334                 ret = mapping->a_ops->direct_IO(&kiocb, &from);
335                 if (ret == PAGE_SIZE) {
336                         count_vm_event(PSWPOUT);
337                         ret = 0;
338                 } else {
339                         /*
340                          * In the case of swap-over-nfs, this can be a
341                          * temporary failure if the system has limited
342                          * memory for allocating transmit buffers.
343                          * Mark the page dirty and avoid
344                          * rotate_reclaimable_page but rate-limit the
345                          * messages but do not flag PageError like
346                          * the normal direct-to-bio case as it could
347                          * be temporary.
348                          */
349                         set_page_dirty(page);
350                         ClearPageReclaim(page);
351                         pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
352                                            page_file_offset(page));
353                 }
354                 end_page_writeback(page);
355                 return ret;
356         }
357
358         ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
359         if (!ret) {
360                 count_swpout_vm_event(page);
361                 return 0;
362         }
363
364         bio = get_swap_bio(GFP_NOIO, page, end_write_func);
365         if (bio == NULL) {
366                 set_page_dirty(page);
367                 unlock_page(page);
368                 return -ENOMEM;
369         }
370         bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
371         bio_associate_blkg_from_page(bio, page);
372         count_swpout_vm_event(page);
373         set_page_writeback(page);
374         unlock_page(page);
375         submit_bio(bio);
376
377         return 0;
378 }
379
380 int swap_readpage(struct page *page, bool synchronous)
381 {
382         struct bio *bio;
383         int ret = 0;
384         struct swap_info_struct *sis = page_swap_info(page);
385         blk_qc_t qc;
386         struct gendisk *disk;
387         unsigned long pflags;
388
389         VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
390         VM_BUG_ON_PAGE(!PageLocked(page), page);
391         VM_BUG_ON_PAGE(PageUptodate(page), page);
392
393         /*
394          * Count submission time as memory stall. When the device is congested,
395          * or the submitting cgroup IO-throttled, submission can be a
396          * significant part of overall IO time.
397          */
398         psi_memstall_enter(&pflags);
399
400         if (frontswap_load(page) == 0) {
401                 SetPageUptodate(page);
402                 unlock_page(page);
403                 goto out;
404         }
405
406         if (data_race(sis->flags & SWP_FS_OPS)) {
407                 struct file *swap_file = sis->swap_file;
408                 struct address_space *mapping = swap_file->f_mapping;
409
410                 ret = mapping->a_ops->readpage(swap_file, page);
411                 if (!ret)
412                         count_vm_event(PSWPIN);
413                 goto out;
414         }
415
416         if (sis->flags & SWP_SYNCHRONOUS_IO) {
417                 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
418                 if (!ret) {
419                         if (trylock_page(page)) {
420                                 swap_slot_free_notify(page);
421                                 unlock_page(page);
422                         }
423
424                         count_vm_event(PSWPIN);
425                         goto out;
426                 }
427         }
428
429         ret = 0;
430         bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
431         if (bio == NULL) {
432                 unlock_page(page);
433                 ret = -ENOMEM;
434                 goto out;
435         }
436         disk = bio->bi_disk;
437         /*
438          * Keep this task valid during swap readpage because the oom killer may
439          * attempt to access it in the page fault retry time check.
440          */
441         bio_set_op_attrs(bio, REQ_OP_READ, 0);
442         if (synchronous) {
443                 bio->bi_opf |= REQ_HIPRI;
444                 get_task_struct(current);
445                 bio->bi_private = current;
446         }
447         count_vm_event(PSWPIN);
448         bio_get(bio);
449         qc = submit_bio(bio);
450         while (synchronous) {
451                 set_current_state(TASK_UNINTERRUPTIBLE);
452                 if (!READ_ONCE(bio->bi_private))
453                         break;
454
455                 if (!blk_poll(disk->queue, qc, true))
456                         blk_io_schedule();
457         }
458         __set_current_state(TASK_RUNNING);
459         bio_put(bio);
460
461 out:
462         psi_memstall_leave(&pflags);
463         return ret;
464 }
465
466 int swap_set_page_dirty(struct page *page)
467 {
468         struct swap_info_struct *sis = page_swap_info(page);
469
470         if (data_race(sis->flags & SWP_FS_OPS)) {
471                 struct address_space *mapping = sis->swap_file->f_mapping;
472
473                 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
474                 return mapping->a_ops->set_page_dirty(page);
475         } else {
476                 return __set_page_dirty_no_writeback(page);
477         }
478 }