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OpenCloudOS-Kernel/mm/page_io.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/mm/page_io.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Swap reorganised 29.12.95,
* Asynchronous swapping added 30.12.95. Stephen Tweedie
* Removed race in async swapping. 14.4.1996. Bruno Haible
* Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
* Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
*/
#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/gfp.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/swapops.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/psi.h>
#include <linux/uio.h>
#include <linux/sched/task.h>
#include <linux/delayacct.h>
#include <linux/zswap.h>
#include "swap.h"
static void __end_swap_bio_write(struct bio *bio)
{
struct folio *folio = bio_first_folio_all(bio);
if (bio->bi_status) {
/*
* We failed to write the page out to swap-space.
* Re-dirty the page in order to avoid it being reclaimed.
* Also print a dire warning that things will go BAD (tm)
* very quickly.
*
* Also clear PG_reclaim to avoid folio_rotate_reclaimable()
*/
folio_mark_dirty(folio);
pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n",
MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
(unsigned long long)bio->bi_iter.bi_sector);
folio_clear_reclaim(folio);
}
folio_end_writeback(folio);
}
static void end_swap_bio_write(struct bio *bio)
{
__end_swap_bio_write(bio);
bio_put(bio);
}
static void __end_swap_bio_read(struct bio *bio)
{
struct folio *folio = bio_first_folio_all(bio);
if (bio->bi_status) {
pr_alert_ratelimited("Read-error on swap-device (%u:%u:%llu)\n",
MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
(unsigned long long)bio->bi_iter.bi_sector);
} else {
folio_mark_uptodate(folio);
}
folio_unlock(folio);
}
static void end_swap_bio_read(struct bio *bio)
{
__end_swap_bio_read(bio);
bio_put(bio);
}
int generic_swapfile_activate(struct swap_info_struct *sis,
struct file *swap_file,
sector_t *span)
{
struct address_space *mapping = swap_file->f_mapping;
struct inode *inode = mapping->host;
unsigned blocks_per_page;
unsigned long page_no;
unsigned blkbits;
sector_t probe_block;
sector_t last_block;
sector_t lowest_block = -1;
sector_t highest_block = 0;
int nr_extents = 0;
int ret;
blkbits = inode->i_blkbits;
blocks_per_page = PAGE_SIZE >> blkbits;
/*
* Map all the blocks into the extent tree. This code doesn't try
* to be very smart.
*/
probe_block = 0;
page_no = 0;
last_block = i_size_read(inode) >> blkbits;
while ((probe_block + blocks_per_page) <= last_block &&
page_no < sis->max) {
unsigned block_in_page;
sector_t first_block;
cond_resched();
first_block = probe_block;
ret = bmap(inode, &first_block);
if (ret || !first_block)
goto bad_bmap;
/*
* It must be PAGE_SIZE aligned on-disk
*/
if (first_block & (blocks_per_page - 1)) {
probe_block++;
goto reprobe;
}
for (block_in_page = 1; block_in_page < blocks_per_page;
block_in_page++) {
sector_t block;
block = probe_block + block_in_page;
ret = bmap(inode, &block);
if (ret || !block)
goto bad_bmap;
if (block != first_block + block_in_page) {
/* Discontiguity */
probe_block++;
goto reprobe;
}
}
first_block >>= (PAGE_SHIFT - blkbits);
if (page_no) { /* exclude the header page */
if (first_block < lowest_block)
lowest_block = first_block;
if (first_block > highest_block)
highest_block = first_block;
}
/*
* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
*/
ret = add_swap_extent(sis, page_no, 1, first_block);
if (ret < 0)
goto out;
nr_extents += ret;
page_no++;
probe_block += blocks_per_page;
reprobe:
continue;
}
ret = nr_extents;
*span = 1 + highest_block - lowest_block;
if (page_no == 0)
page_no = 1; /* force Empty message */
sis->max = page_no;
sis->pages = page_no - 1;
sis->highest_bit = page_no - 1;
out:
return ret;
bad_bmap:
pr_err("swapon: swapfile has holes\n");
ret = -EINVAL;
goto out;
}
/*
* We may have stale swap cache pages in memory: notice
* them here and get rid of the unnecessary final write.
*/
int swap_writepage(struct page *page, struct writeback_control *wbc)
{
struct folio *folio = page_folio(page);
int ret;
if (folio_free_swap(folio)) {
folio_unlock(folio);
return 0;
}
/*
* Arch code may have to preserve more data than just the page
* contents, e.g. memory tags.
*/
ret = arch_prepare_to_swap(&folio->page);
if (ret) {
folio_mark_dirty(folio);
folio_unlock(folio);
return ret;
}
if (zswap_store(folio)) {
folio_start_writeback(folio);
folio_unlock(folio);
folio_end_writeback(folio);
return 0;
}
__swap_writepage(&folio->page, wbc);
return 0;
}
static inline void count_swpout_vm_event(struct folio *folio)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (unlikely(folio_test_pmd_mappable(folio)))
count_vm_event(THP_SWPOUT);
#endif
count_vm_events(PSWPOUT, folio_nr_pages(folio));
}
#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
static void bio_associate_blkg_from_page(struct bio *bio, struct folio *folio)
{
struct cgroup_subsys_state *css;
struct mem_cgroup *memcg;
memcg = folio_memcg(folio);
if (!memcg)
return;
rcu_read_lock();
css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys);
bio_associate_blkg_from_css(bio, css);
rcu_read_unlock();
}
#else
#define bio_associate_blkg_from_page(bio, folio) do { } while (0)
#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
struct swap_iocb {
struct kiocb iocb;
struct bio_vec bvec[SWAP_CLUSTER_MAX];
int pages;
int len;
};
static mempool_t *sio_pool;
int sio_pool_init(void)
{
if (!sio_pool) {
mempool_t *pool = mempool_create_kmalloc_pool(
SWAP_CLUSTER_MAX, sizeof(struct swap_iocb));
if (cmpxchg(&sio_pool, NULL, pool))
mempool_destroy(pool);
}
if (!sio_pool)
return -ENOMEM;
return 0;
}
static void sio_write_complete(struct kiocb *iocb, long ret)
{
struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
struct page *page = sio->bvec[0].bv_page;
int p;
if (ret != sio->len) {
/*
* In the case of swap-over-nfs, this can be a
* temporary failure if the system has limited
* memory for allocating transmit buffers.
* Mark the page dirty and avoid
* folio_rotate_reclaimable but rate-limit the
* messages but do not flag PageError like
* the normal direct-to-bio case as it could
* be temporary.
*/
pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
ret, page_file_offset(page));
for (p = 0; p < sio->pages; p++) {
page = sio->bvec[p].bv_page;
set_page_dirty(page);
ClearPageReclaim(page);
}
} else {
for (p = 0; p < sio->pages; p++)
count_swpout_vm_event(page_folio(sio->bvec[p].bv_page));
}
for (p = 0; p < sio->pages; p++)
end_page_writeback(sio->bvec[p].bv_page);
mempool_free(sio, sio_pool);
}
static void swap_writepage_fs(struct page *page, struct writeback_control *wbc)
{
struct swap_iocb *sio = NULL;
struct swap_info_struct *sis = page_swap_info(page);
struct file *swap_file = sis->swap_file;
loff_t pos = page_file_offset(page);
set_page_writeback(page);
unlock_page(page);
if (wbc->swap_plug)
sio = *wbc->swap_plug;
if (sio) {
if (sio->iocb.ki_filp != swap_file ||
sio->iocb.ki_pos + sio->len != pos) {
swap_write_unplug(sio);
sio = NULL;
}
}
if (!sio) {
sio = mempool_alloc(sio_pool, GFP_NOIO);
init_sync_kiocb(&sio->iocb, swap_file);
sio->iocb.ki_complete = sio_write_complete;
sio->iocb.ki_pos = pos;
sio->pages = 0;
sio->len = 0;
}
bvec_set_page(&sio->bvec[sio->pages], page, thp_size(page), 0);
sio->len += thp_size(page);
sio->pages += 1;
if (sio->pages == ARRAY_SIZE(sio->bvec) || !wbc->swap_plug) {
swap_write_unplug(sio);
sio = NULL;
}
if (wbc->swap_plug)
*wbc->swap_plug = sio;
}
static void swap_writepage_bdev_sync(struct page *page,
struct writeback_control *wbc, struct swap_info_struct *sis)
{
struct bio_vec bv;
struct bio bio;
struct folio *folio = page_folio(page);
bio_init(&bio, sis->bdev, &bv, 1,
REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc));
bio.bi_iter.bi_sector = swap_page_sector(page);
__bio_add_page(&bio, page, thp_size(page), 0);
bio_associate_blkg_from_page(&bio, folio);
count_swpout_vm_event(folio);
folio_start_writeback(folio);
folio_unlock(folio);
submit_bio_wait(&bio);
__end_swap_bio_write(&bio);
}
static void swap_writepage_bdev_async(struct page *page,
struct writeback_control *wbc, struct swap_info_struct *sis)
{
struct bio *bio;
struct folio *folio = page_folio(page);
bio = bio_alloc(sis->bdev, 1,
REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc),
GFP_NOIO);
bio->bi_iter.bi_sector = swap_page_sector(page);
bio->bi_end_io = end_swap_bio_write;
__bio_add_page(bio, page, thp_size(page), 0);
bio_associate_blkg_from_page(bio, folio);
count_swpout_vm_event(folio);
folio_start_writeback(folio);
folio_unlock(folio);
submit_bio(bio);
}
void __swap_writepage(struct page *page, struct writeback_control *wbc)
{
struct swap_info_struct *sis = page_swap_info(page);
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
/*
* ->flags can be updated non-atomicially (scan_swap_map_slots),
* but that will never affect SWP_FS_OPS, so the data_race
* is safe.
*/
if (data_race(sis->flags & SWP_FS_OPS))
swap_writepage_fs(page, wbc);
else if (sis->flags & SWP_SYNCHRONOUS_IO)
swap_writepage_bdev_sync(page, wbc, sis);
else
swap_writepage_bdev_async(page, wbc, sis);
}
void swap_write_unplug(struct swap_iocb *sio)
{
struct iov_iter from;
struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
int ret;
iov_iter_bvec(&from, ITER_SOURCE, sio->bvec, sio->pages, sio->len);
ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
if (ret != -EIOCBQUEUED)
sio_write_complete(&sio->iocb, ret);
}
static void sio_read_complete(struct kiocb *iocb, long ret)
{
struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
int p;
if (ret == sio->len) {
for (p = 0; p < sio->pages; p++) {
struct folio *folio = page_folio(sio->bvec[p].bv_page);
folio_mark_uptodate(folio);
folio_unlock(folio);
}
count_vm_events(PSWPIN, sio->pages);
} else {
for (p = 0; p < sio->pages; p++) {
struct folio *folio = page_folio(sio->bvec[p].bv_page);
folio_unlock(folio);
}
pr_alert_ratelimited("Read-error on swap-device\n");
}
mempool_free(sio, sio_pool);
}
static void swap_readpage_fs(struct page *page,
struct swap_iocb **plug)
{
struct swap_info_struct *sis = page_swap_info(page);
struct swap_iocb *sio = NULL;
loff_t pos = page_file_offset(page);
if (plug)
sio = *plug;
if (sio) {
if (sio->iocb.ki_filp != sis->swap_file ||
sio->iocb.ki_pos + sio->len != pos) {
swap_read_unplug(sio);
sio = NULL;
}
}
if (!sio) {
sio = mempool_alloc(sio_pool, GFP_KERNEL);
init_sync_kiocb(&sio->iocb, sis->swap_file);
sio->iocb.ki_pos = pos;
sio->iocb.ki_complete = sio_read_complete;
sio->pages = 0;
sio->len = 0;
}
bvec_set_page(&sio->bvec[sio->pages], page, thp_size(page), 0);
sio->len += thp_size(page);
sio->pages += 1;
if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) {
swap_read_unplug(sio);
sio = NULL;
}
if (plug)
*plug = sio;
}
static void swap_readpage_bdev_sync(struct page *page,
struct swap_info_struct *sis)
{
struct bio_vec bv;
struct bio bio;
bio_init(&bio, sis->bdev, &bv, 1, REQ_OP_READ);
bio.bi_iter.bi_sector = swap_page_sector(page);
__bio_add_page(&bio, page, thp_size(page), 0);
/*
* Keep this task valid during swap readpage because the oom killer may
* attempt to access it in the page fault retry time check.
*/
get_task_struct(current);
count_vm_event(PSWPIN);
submit_bio_wait(&bio);
__end_swap_bio_read(&bio);
put_task_struct(current);
}
static void swap_readpage_bdev_async(struct page *page,
struct swap_info_struct *sis)
{
struct bio *bio;
bio = bio_alloc(sis->bdev, 1, REQ_OP_READ, GFP_KERNEL);
bio->bi_iter.bi_sector = swap_page_sector(page);
bio->bi_end_io = end_swap_bio_read;
__bio_add_page(bio, page, thp_size(page), 0);
count_vm_event(PSWPIN);
submit_bio(bio);
}
void swap_readpage(struct page *page, bool synchronous, struct swap_iocb **plug)
{
struct folio *folio = page_folio(page);
struct swap_info_struct *sis = page_swap_info(page);
bool workingset = folio_test_workingset(folio);
unsigned long pflags;
bool in_thrashing;
VM_BUG_ON_FOLIO(!folio_test_swapcache(folio) && !synchronous, folio);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(folio_test_uptodate(folio), folio);
/*
* Count submission time as memory stall and delay. When the device
* is congested, or the submitting cgroup IO-throttled, submission
* can be a significant part of overall IO time.
*/
if (workingset) {
delayacct_thrashing_start(&in_thrashing);
psi_memstall_enter(&pflags);
}
delayacct_swapin_start();
if (zswap_load(folio)) {
folio_mark_uptodate(folio);
folio_unlock(folio);
} else if (data_race(sis->flags & SWP_FS_OPS)) {
swap_readpage_fs(page, plug);
} else if (synchronous || (sis->flags & SWP_SYNCHRONOUS_IO)) {
swap_readpage_bdev_sync(page, sis);
} else {
swap_readpage_bdev_async(page, sis);
}
if (workingset) {
delayacct_thrashing_end(&in_thrashing);
psi_memstall_leave(&pflags);
}
delayacct_swapin_end();
}
void __swap_read_unplug(struct swap_iocb *sio)
{
struct iov_iter from;
struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
int ret;
iov_iter_bvec(&from, ITER_DEST, sio->bvec, sio->pages, sio->len);
ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
if (ret != -EIOCBQUEUED)
sio_read_complete(&sio->iocb, ret);
}
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