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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - mm/page_io.c
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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
14 #include <linux/kernel_stat.h>
15 #include <linux/gfp.h>
16 #include <linux/pagemap.h>
17 #include <linux/swap.h>
18 #include <linux/bio.h>
19 #include <linux/swapops.h>
20 #include <linux/buffer_head.h>
21 #include <linux/writeback.h>
22 #include <linux/frontswap.h>
23 #include <linux/blkdev.h>
24 #include <linux/uio.h>
25 #include <asm/pgtable.h>
27 static struct bio
*get_swap_bio(gfp_t gfp_flags
,
28 struct page
*page
, bio_end_io_t end_io
)
32 bio
= bio_alloc(gfp_flags
, 1);
34 bio
->bi_iter
.bi_sector
= map_swap_page(page
, &bio
->bi_bdev
);
35 bio
->bi_iter
.bi_sector
<<= PAGE_SHIFT
- 9;
36 bio
->bi_io_vec
[0].bv_page
= page
;
37 bio
->bi_io_vec
[0].bv_len
= PAGE_SIZE
;
38 bio
->bi_io_vec
[0].bv_offset
= 0;
40 bio
->bi_iter
.bi_size
= PAGE_SIZE
;
41 bio
->bi_end_io
= end_io
;
46 void end_swap_bio_write(struct bio
*bio
, int err
)
48 const int uptodate
= test_bit(BIO_UPTODATE
, &bio
->bi_flags
);
49 struct page
*page
= bio
->bi_io_vec
[0].bv_page
;
54 * We failed to write the page out to swap-space.
55 * Re-dirty the page in order to avoid it being reclaimed.
56 * Also print a dire warning that things will go BAD (tm)
59 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
62 printk(KERN_ALERT
"Write-error on swap-device (%u:%u:%Lu)\n",
63 imajor(bio
->bi_bdev
->bd_inode
),
64 iminor(bio
->bi_bdev
->bd_inode
),
65 (unsigned long long)bio
->bi_iter
.bi_sector
);
66 ClearPageReclaim(page
);
68 end_page_writeback(page
);
72 void end_swap_bio_read(struct bio
*bio
, int err
)
74 const int uptodate
= test_bit(BIO_UPTODATE
, &bio
->bi_flags
);
75 struct page
*page
= bio
->bi_io_vec
[0].bv_page
;
79 ClearPageUptodate(page
);
80 printk(KERN_ALERT
"Read-error on swap-device (%u:%u:%Lu)\n",
81 imajor(bio
->bi_bdev
->bd_inode
),
82 iminor(bio
->bi_bdev
->bd_inode
),
83 (unsigned long long)bio
->bi_iter
.bi_sector
);
87 SetPageUptodate(page
);
90 * There is no guarantee that the page is in swap cache - the software
91 * suspend code (at least) uses end_swap_bio_read() against a non-
92 * swapcache page. So we must check PG_swapcache before proceeding with
95 if (likely(PageSwapCache(page
))) {
96 struct swap_info_struct
*sis
;
98 sis
= page_swap_info(page
);
99 if (sis
->flags
& SWP_BLKDEV
) {
101 * The swap subsystem performs lazy swap slot freeing,
102 * expecting that the page will be swapped out again.
103 * So we can avoid an unnecessary write if the page
105 * This is good for real swap storage because we can
106 * reduce unnecessary I/O and enhance wear-leveling
107 * if an SSD is used as the as swap device.
108 * But if in-memory swap device (eg zram) is used,
109 * this causes a duplicated copy between uncompressed
110 * data in VM-owned memory and compressed data in
111 * zram-owned memory. So let's free zram-owned memory
112 * and make the VM-owned decompressed page *dirty*,
113 * so the page should be swapped out somewhere again if
114 * we again wish to reclaim it.
116 struct gendisk
*disk
= sis
->bdev
->bd_disk
;
117 if (disk
->fops
->swap_slot_free_notify
) {
119 unsigned long offset
;
121 entry
.val
= page_private(page
);
122 offset
= swp_offset(entry
);
125 disk
->fops
->swap_slot_free_notify(sis
->bdev
,
136 int generic_swapfile_activate(struct swap_info_struct
*sis
,
137 struct file
*swap_file
,
140 struct address_space
*mapping
= swap_file
->f_mapping
;
141 struct inode
*inode
= mapping
->host
;
142 unsigned blocks_per_page
;
143 unsigned long page_no
;
145 sector_t probe_block
;
147 sector_t lowest_block
= -1;
148 sector_t highest_block
= 0;
152 blkbits
= inode
->i_blkbits
;
153 blocks_per_page
= PAGE_SIZE
>> blkbits
;
156 * Map all the blocks into the extent list. This code doesn't try
161 last_block
= i_size_read(inode
) >> blkbits
;
162 while ((probe_block
+ blocks_per_page
) <= last_block
&&
163 page_no
< sis
->max
) {
164 unsigned block_in_page
;
165 sector_t first_block
;
167 first_block
= bmap(inode
, probe_block
);
168 if (first_block
== 0)
172 * It must be PAGE_SIZE aligned on-disk
174 if (first_block
& (blocks_per_page
- 1)) {
179 for (block_in_page
= 1; block_in_page
< blocks_per_page
;
183 block
= bmap(inode
, probe_block
+ block_in_page
);
186 if (block
!= first_block
+ block_in_page
) {
193 first_block
>>= (PAGE_SHIFT
- blkbits
);
194 if (page_no
) { /* exclude the header page */
195 if (first_block
< lowest_block
)
196 lowest_block
= first_block
;
197 if (first_block
> highest_block
)
198 highest_block
= first_block
;
202 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
204 ret
= add_swap_extent(sis
, page_no
, 1, first_block
);
209 probe_block
+= blocks_per_page
;
214 *span
= 1 + highest_block
- lowest_block
;
216 page_no
= 1; /* force Empty message */
218 sis
->pages
= page_no
- 1;
219 sis
->highest_bit
= page_no
- 1;
223 printk(KERN_ERR
"swapon: swapfile has holes\n");
229 * We may have stale swap cache pages in memory: notice
230 * them here and get rid of the unnecessary final write.
232 int swap_writepage(struct page
*page
, struct writeback_control
*wbc
)
236 if (try_to_free_swap(page
)) {
240 if (frontswap_store(page
) == 0) {
241 set_page_writeback(page
);
243 end_page_writeback(page
);
246 ret
= __swap_writepage(page
, wbc
, end_swap_bio_write
);
251 static sector_t
swap_page_sector(struct page
*page
)
253 return (sector_t
)__page_file_index(page
) << (PAGE_CACHE_SHIFT
- 9);
256 int __swap_writepage(struct page
*page
, struct writeback_control
*wbc
,
257 void (*end_write_func
)(struct bio
*, int))
261 struct swap_info_struct
*sis
= page_swap_info(page
);
263 if (sis
->flags
& SWP_FILE
) {
265 struct file
*swap_file
= sis
->swap_file
;
266 struct address_space
*mapping
= swap_file
->f_mapping
;
267 struct bio_vec bv
= {
272 struct iov_iter from
;
274 iov_iter_bvec(&from
, ITER_BVEC
| WRITE
, &bv
, 1, PAGE_SIZE
);
275 init_sync_kiocb(&kiocb
, swap_file
);
276 kiocb
.ki_pos
= page_file_offset(page
);
278 set_page_writeback(page
);
280 ret
= mapping
->a_ops
->direct_IO(&kiocb
, &from
, kiocb
.ki_pos
);
281 if (ret
== PAGE_SIZE
) {
282 count_vm_event(PSWPOUT
);
286 * In the case of swap-over-nfs, this can be a
287 * temporary failure if the system has limited
288 * memory for allocating transmit buffers.
289 * Mark the page dirty and avoid
290 * rotate_reclaimable_page but rate-limit the
291 * messages but do not flag PageError like
292 * the normal direct-to-bio case as it could
295 set_page_dirty(page
);
296 ClearPageReclaim(page
);
297 pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
298 page_file_offset(page
));
300 end_page_writeback(page
);
304 ret
= bdev_write_page(sis
->bdev
, swap_page_sector(page
), page
, wbc
);
306 count_vm_event(PSWPOUT
);
311 bio
= get_swap_bio(GFP_NOIO
, page
, end_write_func
);
313 set_page_dirty(page
);
318 if (wbc
->sync_mode
== WB_SYNC_ALL
)
320 count_vm_event(PSWPOUT
);
321 set_page_writeback(page
);
328 int swap_readpage(struct page
*page
)
332 struct swap_info_struct
*sis
= page_swap_info(page
);
334 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
335 VM_BUG_ON_PAGE(PageUptodate(page
), page
);
336 if (frontswap_load(page
) == 0) {
337 SetPageUptodate(page
);
342 if (sis
->flags
& SWP_FILE
) {
343 struct file
*swap_file
= sis
->swap_file
;
344 struct address_space
*mapping
= swap_file
->f_mapping
;
346 ret
= mapping
->a_ops
->readpage(swap_file
, page
);
348 count_vm_event(PSWPIN
);
352 ret
= bdev_read_page(sis
->bdev
, swap_page_sector(page
), page
);
354 count_vm_event(PSWPIN
);
359 bio
= get_swap_bio(GFP_KERNEL
, page
, end_swap_bio_read
);
365 count_vm_event(PSWPIN
);
366 submit_bio(READ
, bio
);
371 int swap_set_page_dirty(struct page
*page
)
373 struct swap_info_struct
*sis
= page_swap_info(page
);
375 if (sis
->flags
& SWP_FILE
) {
376 struct address_space
*mapping
= sis
->swap_file
->f_mapping
;
377 return mapping
->a_ops
->set_page_dirty(page
);
379 return __set_page_dirty_no_writeback(page
);