blob: ff74e512f0292987c4d2e2e738aab0c4c6263fc3 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/page_io.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 *
6 * Swap reorganised 29.12.95,
7 * Asynchronous swapping added 30.12.95. Stephen Tweedie
8 * Removed race in async swapping. 14.4.1996. Bruno Haible
9 * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
10 * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
11 */
12
13#include <linux/mm.h>
14#include <linux/kernel_stat.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090015#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/pagemap.h>
17#include <linux/swap.h>
18#include <linux/bio.h>
19#include <linux/swapops.h>
Mel Gorman62c230b2012-07-31 16:44:55 -070020#include <linux/buffer_head.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/writeback.h>
Dan Magenheimer38b5faf2012-04-09 17:08:06 -060022#include <linux/frontswap.h>
Minchan Kimb430e9d2013-07-03 15:01:24 -070023#include <linux/blkdev.h>
Christoph Hellwige2e40f22015-02-22 08:58:50 -080024#include <linux/uio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <asm/pgtable.h>
26
Hugh Dickinsf29ad6a2009-12-14 17:58:40 -080027static struct bio *get_swap_bio(gfp_t gfp_flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 struct page *page, bio_end_io_t end_io)
29{
30 struct bio *bio;
31
32 bio = bio_alloc(gfp_flags, 1);
33 if (bio) {
Kent Overstreet4f024f32013-10-11 15:44:27 -070034 bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
35 bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 bio->bi_end_io = end_io;
Kent Overstreet6cf66b42014-12-22 12:48:42 +010037
38 bio_add_page(bio, page, PAGE_SIZE, 0);
39 BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 }
41 return bio;
42}
43
Christoph Hellwig4246a0b2015-07-20 15:29:37 +020044void end_swap_bio_write(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -070045{
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 struct page *page = bio->bi_io_vec[0].bv_page;
47
Christoph Hellwig4246a0b2015-07-20 15:29:37 +020048 if (bio->bi_error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 SetPageError(page);
Peter Zijlstra6ddab3b2006-09-25 23:31:26 -070050 /*
51 * We failed to write the page out to swap-space.
52 * Re-dirty the page in order to avoid it being reclaimed.
53 * Also print a dire warning that things will go BAD (tm)
54 * very quickly.
55 *
56 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
57 */
58 set_page_dirty(page);
Joe Perches11705322016-03-17 14:19:50 -070059 pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
60 imajor(bio->bi_bdev->bd_inode),
61 iminor(bio->bi_bdev->bd_inode),
62 (unsigned long long)bio->bi_iter.bi_sector);
Peter Zijlstra6ddab3b2006-09-25 23:31:26 -070063 ClearPageReclaim(page);
64 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 end_page_writeback(page);
66 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067}
68
Christoph Hellwig4246a0b2015-07-20 15:29:37 +020069static void end_swap_bio_read(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 struct page *page = bio->bi_io_vec[0].bv_page;
72
Christoph Hellwig4246a0b2015-07-20 15:29:37 +020073 if (bio->bi_error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 SetPageError(page);
75 ClearPageUptodate(page);
Joe Perches11705322016-03-17 14:19:50 -070076 pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
77 imajor(bio->bi_bdev->bd_inode),
78 iminor(bio->bi_bdev->bd_inode),
79 (unsigned long long)bio->bi_iter.bi_sector);
Minchan Kimb430e9d2013-07-03 15:01:24 -070080 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 }
Minchan Kimb430e9d2013-07-03 15:01:24 -070082
83 SetPageUptodate(page);
84
85 /*
86 * There is no guarantee that the page is in swap cache - the software
87 * suspend code (at least) uses end_swap_bio_read() against a non-
88 * swapcache page. So we must check PG_swapcache before proceeding with
89 * this optimization.
90 */
91 if (likely(PageSwapCache(page))) {
92 struct swap_info_struct *sis;
93
94 sis = page_swap_info(page);
95 if (sis->flags & SWP_BLKDEV) {
96 /*
97 * The swap subsystem performs lazy swap slot freeing,
98 * expecting that the page will be swapped out again.
99 * So we can avoid an unnecessary write if the page
100 * isn't redirtied.
101 * This is good for real swap storage because we can
102 * reduce unnecessary I/O and enhance wear-leveling
103 * if an SSD is used as the as swap device.
104 * But if in-memory swap device (eg zram) is used,
105 * this causes a duplicated copy between uncompressed
106 * data in VM-owned memory and compressed data in
107 * zram-owned memory. So let's free zram-owned memory
108 * and make the VM-owned decompressed page *dirty*,
109 * so the page should be swapped out somewhere again if
110 * we again wish to reclaim it.
111 */
112 struct gendisk *disk = sis->bdev->bd_disk;
113 if (disk->fops->swap_slot_free_notify) {
114 swp_entry_t entry;
115 unsigned long offset;
116
117 entry.val = page_private(page);
118 offset = swp_offset(entry);
119
120 SetPageDirty(page);
121 disk->fops->swap_slot_free_notify(sis->bdev,
122 offset);
123 }
124 }
125 }
126
127out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 unlock_page(page);
129 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
Mel Gormana509bc12012-07-31 16:44:57 -0700132int generic_swapfile_activate(struct swap_info_struct *sis,
133 struct file *swap_file,
134 sector_t *span)
135{
136 struct address_space *mapping = swap_file->f_mapping;
137 struct inode *inode = mapping->host;
138 unsigned blocks_per_page;
139 unsigned long page_no;
140 unsigned blkbits;
141 sector_t probe_block;
142 sector_t last_block;
143 sector_t lowest_block = -1;
144 sector_t highest_block = 0;
145 int nr_extents = 0;
146 int ret;
147
148 blkbits = inode->i_blkbits;
149 blocks_per_page = PAGE_SIZE >> blkbits;
150
151 /*
152 * Map all the blocks into the extent list. This code doesn't try
153 * to be very smart.
154 */
155 probe_block = 0;
156 page_no = 0;
157 last_block = i_size_read(inode) >> blkbits;
158 while ((probe_block + blocks_per_page) <= last_block &&
159 page_no < sis->max) {
160 unsigned block_in_page;
161 sector_t first_block;
162
163 first_block = bmap(inode, probe_block);
164 if (first_block == 0)
165 goto bad_bmap;
166
167 /*
168 * It must be PAGE_SIZE aligned on-disk
169 */
170 if (first_block & (blocks_per_page - 1)) {
171 probe_block++;
172 goto reprobe;
173 }
174
175 for (block_in_page = 1; block_in_page < blocks_per_page;
176 block_in_page++) {
177 sector_t block;
178
179 block = bmap(inode, probe_block + block_in_page);
180 if (block == 0)
181 goto bad_bmap;
182 if (block != first_block + block_in_page) {
183 /* Discontiguity */
184 probe_block++;
185 goto reprobe;
186 }
187 }
188
189 first_block >>= (PAGE_SHIFT - blkbits);
190 if (page_no) { /* exclude the header page */
191 if (first_block < lowest_block)
192 lowest_block = first_block;
193 if (first_block > highest_block)
194 highest_block = first_block;
195 }
196
197 /*
198 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
199 */
200 ret = add_swap_extent(sis, page_no, 1, first_block);
201 if (ret < 0)
202 goto out;
203 nr_extents += ret;
204 page_no++;
205 probe_block += blocks_per_page;
206reprobe:
207 continue;
208 }
209 ret = nr_extents;
210 *span = 1 + highest_block - lowest_block;
211 if (page_no == 0)
212 page_no = 1; /* force Empty message */
213 sis->max = page_no;
214 sis->pages = page_no - 1;
215 sis->highest_bit = page_no - 1;
216out:
217 return ret;
218bad_bmap:
Joe Perches11705322016-03-17 14:19:50 -0700219 pr_err("swapon: swapfile has holes\n");
Mel Gormana509bc12012-07-31 16:44:57 -0700220 ret = -EINVAL;
221 goto out;
222}
223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224/*
225 * We may have stale swap cache pages in memory: notice
226 * them here and get rid of the unnecessary final write.
227 */
228int swap_writepage(struct page *page, struct writeback_control *wbc)
229{
Seth Jennings2f772e62013-04-29 15:08:34 -0700230 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800232 if (try_to_free_swap(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 unlock_page(page);
234 goto out;
235 }
Konrad Rzeszutek Wilk165c8ae2012-05-15 11:32:15 -0400236 if (frontswap_store(page) == 0) {
Dan Magenheimer38b5faf2012-04-09 17:08:06 -0600237 set_page_writeback(page);
238 unlock_page(page);
239 end_page_writeback(page);
240 goto out;
241 }
Seth Jennings1eec6702013-04-29 15:08:35 -0700242 ret = __swap_writepage(page, wbc, end_swap_bio_write);
Seth Jennings2f772e62013-04-29 15:08:34 -0700243out:
244 return ret;
245}
246
Matthew Wilcoxdd6bd0d2014-06-04 16:07:48 -0700247static sector_t swap_page_sector(struct page *page)
248{
249 return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
250}
251
Seth Jennings1eec6702013-04-29 15:08:35 -0700252int __swap_writepage(struct page *page, struct writeback_control *wbc,
Christoph Hellwig4246a0b2015-07-20 15:29:37 +0200253 bio_end_io_t end_write_func)
Seth Jennings2f772e62013-04-29 15:08:34 -0700254{
255 struct bio *bio;
Matthew Wilcoxdd6bd0d2014-06-04 16:07:48 -0700256 int ret, rw = WRITE;
Seth Jennings2f772e62013-04-29 15:08:34 -0700257 struct swap_info_struct *sis = page_swap_info(page);
Mel Gorman62c230b2012-07-31 16:44:55 -0700258
259 if (sis->flags & SWP_FILE) {
260 struct kiocb kiocb;
261 struct file *swap_file = sis->swap_file;
262 struct address_space *mapping = swap_file->f_mapping;
Al Viro62a80672014-04-04 23:12:29 -0400263 struct bio_vec bv = {
264 .bv_page = page,
265 .bv_len = PAGE_SIZE,
266 .bv_offset = 0
Mel Gorman62c230b2012-07-31 16:44:55 -0700267 };
Al Viro05afcb72015-01-23 01:08:07 -0500268 struct iov_iter from;
Mel Gorman62c230b2012-07-31 16:44:55 -0700269
Al Viro05afcb72015-01-23 01:08:07 -0500270 iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
Mel Gorman62c230b2012-07-31 16:44:55 -0700271 init_sync_kiocb(&kiocb, swap_file);
272 kiocb.ki_pos = page_file_offset(page);
Mel Gorman62c230b2012-07-31 16:44:55 -0700273
Mel Gorman0cdc4442013-04-29 15:08:48 -0700274 set_page_writeback(page);
Mel Gorman62c230b2012-07-31 16:44:55 -0700275 unlock_page(page);
Omar Sandoval22c61862015-03-16 04:33:53 -0700276 ret = mapping->a_ops->direct_IO(&kiocb, &from, kiocb.ki_pos);
Mel Gorman62c230b2012-07-31 16:44:55 -0700277 if (ret == PAGE_SIZE) {
278 count_vm_event(PSWPOUT);
279 ret = 0;
Jerome Marchand2d30d312013-04-29 15:08:47 -0700280 } else {
Mel Gorman0cdc4442013-04-29 15:08:48 -0700281 /*
282 * In the case of swap-over-nfs, this can be a
283 * temporary failure if the system has limited
284 * memory for allocating transmit buffers.
285 * Mark the page dirty and avoid
286 * rotate_reclaimable_page but rate-limit the
287 * messages but do not flag PageError like
288 * the normal direct-to-bio case as it could
289 * be temporary.
290 */
Jerome Marchand2d30d312013-04-29 15:08:47 -0700291 set_page_dirty(page);
Mel Gorman0cdc4442013-04-29 15:08:48 -0700292 ClearPageReclaim(page);
Joe Perches11705322016-03-17 14:19:50 -0700293 pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
294 page_file_offset(page));
Mel Gorman62c230b2012-07-31 16:44:55 -0700295 }
Mel Gorman0cdc4442013-04-29 15:08:48 -0700296 end_page_writeback(page);
Mel Gorman62c230b2012-07-31 16:44:55 -0700297 return ret;
298 }
299
Matthew Wilcoxdd6bd0d2014-06-04 16:07:48 -0700300 ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
301 if (!ret) {
302 count_vm_event(PSWPOUT);
303 return 0;
304 }
305
306 ret = 0;
Seth Jennings1eec6702013-04-29 15:08:35 -0700307 bio = get_swap_bio(GFP_NOIO, page, end_write_func);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 if (bio == NULL) {
309 set_page_dirty(page);
310 unlock_page(page);
311 ret = -ENOMEM;
312 goto out;
313 }
314 if (wbc->sync_mode == WB_SYNC_ALL)
Jens Axboe721a9602011-03-09 11:56:30 +0100315 rw |= REQ_SYNC;
Christoph Lameterf8891e52006-06-30 01:55:45 -0700316 count_vm_event(PSWPOUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 set_page_writeback(page);
318 unlock_page(page);
319 submit_bio(rw, bio);
320out:
321 return ret;
322}
323
Minchan Kimaca8bf32009-06-16 15:33:02 -0700324int swap_readpage(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325{
326 struct bio *bio;
327 int ret = 0;
Mel Gorman62c230b2012-07-31 16:44:55 -0700328 struct swap_info_struct *sis = page_swap_info(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329
Sasha Levin309381fea2014-01-23 15:52:54 -0800330 VM_BUG_ON_PAGE(!PageLocked(page), page);
331 VM_BUG_ON_PAGE(PageUptodate(page), page);
Konrad Rzeszutek Wilk165c8ae2012-05-15 11:32:15 -0400332 if (frontswap_load(page) == 0) {
Dan Magenheimer38b5faf2012-04-09 17:08:06 -0600333 SetPageUptodate(page);
334 unlock_page(page);
335 goto out;
336 }
Mel Gorman62c230b2012-07-31 16:44:55 -0700337
338 if (sis->flags & SWP_FILE) {
339 struct file *swap_file = sis->swap_file;
340 struct address_space *mapping = swap_file->f_mapping;
341
342 ret = mapping->a_ops->readpage(swap_file, page);
343 if (!ret)
344 count_vm_event(PSWPIN);
345 return ret;
346 }
347
Matthew Wilcoxdd6bd0d2014-06-04 16:07:48 -0700348 ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
349 if (!ret) {
350 count_vm_event(PSWPIN);
351 return 0;
352 }
353
354 ret = 0;
Hugh Dickinsf29ad6a2009-12-14 17:58:40 -0800355 bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 if (bio == NULL) {
357 unlock_page(page);
358 ret = -ENOMEM;
359 goto out;
360 }
Christoph Lameterf8891e52006-06-30 01:55:45 -0700361 count_vm_event(PSWPIN);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 submit_bio(READ, bio);
363out:
364 return ret;
365}
Mel Gorman62c230b2012-07-31 16:44:55 -0700366
367int swap_set_page_dirty(struct page *page)
368{
369 struct swap_info_struct *sis = page_swap_info(page);
370
371 if (sis->flags & SWP_FILE) {
372 struct address_space *mapping = sis->swap_file->f_mapping;
373 return mapping->a_ops->set_page_dirty(page);
374 } else {
375 return __set_page_dirty_no_writeback(page);
376 }
377}