| // 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); |
| 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; |
| } |
| if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) { |
| folio_mark_dirty(folio); |
| return AOP_WRITEPAGE_ACTIVATE; |
| } |
| |
| __swap_writepage(folio, 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_memcg_folio_events(folio, THP_SWPOUT, 1); |
| count_vm_event(THP_SWPOUT); |
| } |
| count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_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); |
| } |
| } |
| |
| 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 folio *folio, struct writeback_control *wbc) |
| { |
| struct swap_iocb *sio = NULL; |
| struct swap_info_struct *sis = swp_swap_info(folio->swap); |
| struct file *swap_file = sis->swap_file; |
| loff_t pos = folio_file_pos(folio); |
| |
| count_swpout_vm_event(folio); |
| folio_start_writeback(folio); |
| folio_unlock(folio); |
| 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_folio(&sio->bvec[sio->pages], folio, folio_size(folio), 0); |
| sio->len += folio_size(folio); |
| 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 folio *folio, |
| struct writeback_control *wbc, struct swap_info_struct *sis) |
| { |
| struct bio_vec bv; |
| struct bio bio; |
| |
| bio_init(&bio, sis->bdev, &bv, 1, |
| REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc)); |
| bio.bi_iter.bi_sector = swap_folio_sector(folio); |
| bio_add_folio_nofail(&bio, folio, folio_size(folio), 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 folio *folio, |
| struct writeback_control *wbc, struct swap_info_struct *sis) |
| { |
| struct bio *bio; |
| |
| bio = bio_alloc(sis->bdev, 1, |
| REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc), |
| GFP_NOIO); |
| bio->bi_iter.bi_sector = swap_folio_sector(folio); |
| bio->bi_end_io = end_swap_bio_write; |
| bio_add_folio_nofail(bio, folio, folio_size(folio), 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 folio *folio, struct writeback_control *wbc) |
| { |
| struct swap_info_struct *sis = swp_swap_info(folio->swap); |
| |
| VM_BUG_ON_FOLIO(!folio_test_swapcache(folio), folio); |
| /* |
| * ->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(folio, wbc); |
| else if (sis->flags & SWP_SYNCHRONOUS_IO) |
| swap_writepage_bdev_sync(folio, wbc, sis); |
| else |
| swap_writepage_bdev_async(folio, 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_read_folio_fs(struct folio *folio, struct swap_iocb **plug) |
| { |
| struct swap_info_struct *sis = swp_swap_info(folio->swap); |
| struct swap_iocb *sio = NULL; |
| loff_t pos = folio_file_pos(folio); |
| |
| 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_folio(&sio->bvec[sio->pages], folio, folio_size(folio), 0); |
| sio->len += folio_size(folio); |
| sio->pages += 1; |
| if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) { |
| swap_read_unplug(sio); |
| sio = NULL; |
| } |
| if (plug) |
| *plug = sio; |
| } |
| |
| static void swap_read_folio_bdev_sync(struct folio *folio, |
| 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_folio_sector(folio); |
| bio_add_folio_nofail(&bio, folio, folio_size(folio), 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_read_folio_bdev_async(struct folio *folio, |
| 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_folio_sector(folio); |
| bio->bi_end_io = end_swap_bio_read; |
| bio_add_folio_nofail(bio, folio, folio_size(folio), 0); |
| count_vm_event(PSWPIN); |
| submit_bio(bio); |
| } |
| |
| void swap_read_folio(struct folio *folio, bool synchronous, |
| struct swap_iocb **plug) |
| { |
| struct swap_info_struct *sis = swp_swap_info(folio->swap); |
| 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_read_folio_fs(folio, plug); |
| } else if (synchronous || (sis->flags & SWP_SYNCHRONOUS_IO)) { |
| swap_read_folio_bdev_sync(folio, sis); |
| } else { |
| swap_read_folio_bdev_async(folio, 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); |
| } |