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-rw-r--r--mm/page_io.c537
1 files changed, 537 insertions, 0 deletions
diff --git a/mm/page_io.c b/mm/page_io.c
new file mode 100644
index 000000000..3a5f921b9
--- /dev/null
+++ b/mm/page_io.c
@@ -0,0 +1,537 @@
+// 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/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/frontswap.h>
+#include <linux/blkdev.h>
+#include <linux/psi.h>
+#include <linux/uio.h>
+#include <linux/sched/task.h>
+#include <linux/delayacct.h>
+#include "swap.h"
+
+static void end_swap_bio_write(struct bio *bio)
+{
+ struct page *page = bio_first_page_all(bio);
+
+ if (bio->bi_status) {
+ SetPageError(page);
+ /*
+ * 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()
+ */
+ set_page_dirty(page);
+ 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);
+ ClearPageReclaim(page);
+ }
+ end_page_writeback(page);
+ bio_put(bio);
+}
+
+static void end_swap_bio_read(struct bio *bio)
+{
+ struct page *page = bio_first_page_all(bio);
+ struct task_struct *waiter = bio->bi_private;
+
+ if (bio->bi_status) {
+ SetPageError(page);
+ ClearPageUptodate(page);
+ 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);
+ goto out;
+ }
+
+ SetPageUptodate(page);
+out:
+ unlock_page(page);
+ WRITE_ONCE(bio->bi_private, NULL);
+ bio_put(bio);
+ if (waiter) {
+ blk_wake_io_task(waiter);
+ put_task_struct(waiter);
+ }
+}
+
+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 = 0;
+
+ if (folio_free_swap(folio)) {
+ folio_unlock(folio);
+ goto out;
+ }
+ /*
+ * 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);
+ goto out;
+ }
+ if (frontswap_store(&folio->page) == 0) {
+ folio_start_writeback(folio);
+ folio_unlock(folio);
+ folio_end_writeback(folio);
+ goto out;
+ }
+ ret = __swap_writepage(&folio->page, wbc);
+out:
+ return ret;
+}
+
+static inline void count_swpout_vm_event(struct page *page)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ if (unlikely(PageTransHuge(page)))
+ count_vm_event(THP_SWPOUT);
+#endif
+ count_vm_events(PSWPOUT, thp_nr_pages(page));
+}
+
+#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
+static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
+{
+ struct cgroup_subsys_state *css;
+ struct mem_cgroup *memcg;
+
+ memcg = page_memcg(page);
+ 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, page) 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(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 int 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;
+ }
+ sio->bvec[sio->pages].bv_page = page;
+ sio->bvec[sio->pages].bv_len = thp_size(page);
+ sio->bvec[sio->pages].bv_offset = 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;
+
+ return 0;
+}
+
+int __swap_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct bio *bio;
+ int ret;
+ 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))
+ return swap_writepage_fs(page, wbc);
+
+ ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
+ if (!ret) {
+ count_swpout_vm_event(page);
+ return 0;
+ }
+
+ 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, page);
+ count_swpout_vm_event(page);
+ set_page_writeback(page);
+ unlock_page(page);
+ submit_bio(bio);
+
+ return 0;
+}
+
+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 page *page = sio->bvec[p].bv_page;
+
+ SetPageUptodate(page);
+ unlock_page(page);
+ }
+ count_vm_events(PSWPIN, sio->pages);
+ } else {
+ for (p = 0; p < sio->pages; p++) {
+ struct page *page = sio->bvec[p].bv_page;
+
+ SetPageError(page);
+ ClearPageUptodate(page);
+ unlock_page(page);
+ }
+ 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;
+ }
+ sio->bvec[sio->pages].bv_page = page;
+ sio->bvec[sio->pages].bv_len = thp_size(page);
+ sio->bvec[sio->pages].bv_offset = 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;
+}
+
+int swap_readpage(struct page *page, bool synchronous,
+ struct swap_iocb **plug)
+{
+ struct bio *bio;
+ int ret = 0;
+ struct swap_info_struct *sis = page_swap_info(page);
+ bool workingset = PageWorkingset(page);
+ unsigned long pflags;
+ bool in_thrashing;
+
+ VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(PageUptodate(page), page);
+
+ /*
+ * 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 (frontswap_load(page) == 0) {
+ SetPageUptodate(page);
+ unlock_page(page);
+ goto out;
+ }
+
+ if (data_race(sis->flags & SWP_FS_OPS)) {
+ swap_readpage_fs(page, plug);
+ goto out;
+ }
+
+ if (sis->flags & SWP_SYNCHRONOUS_IO) {
+ ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
+ if (!ret) {
+ count_vm_event(PSWPIN);
+ goto out;
+ }
+ }
+
+ ret = 0;
+ 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);
+ /*
+ * Keep this task valid during swap readpage because the oom killer may
+ * attempt to access it in the page fault retry time check.
+ */
+ if (synchronous) {
+ get_task_struct(current);
+ bio->bi_private = current;
+ }
+ count_vm_event(PSWPIN);
+ bio_get(bio);
+ submit_bio(bio);
+ while (synchronous) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (!READ_ONCE(bio->bi_private))
+ break;
+
+ blk_io_schedule();
+ }
+ __set_current_state(TASK_RUNNING);
+ bio_put(bio);
+
+out:
+ if (workingset) {
+ delayacct_thrashing_end(&in_thrashing);
+ psi_memstall_leave(&pflags);
+ }
+ delayacct_swapin_end();
+ return ret;
+}
+
+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);
+}