diff options
Diffstat (limited to '')
| -rw-r--r-- | mm/filemap.c | 4307 |
1 files changed, 4307 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c new file mode 100644 index 0000000000..b1ef7be120 --- /dev/null +++ b/mm/filemap.c @@ -0,0 +1,4307 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/mm/filemap.c + * + * Copyright (C) 1994-1999 Linus Torvalds + */ + +/* + * This file handles the generic file mmap semantics used by + * most "normal" filesystems (but you don't /have/ to use this: + * the NFS filesystem used to do this differently, for example) + */ +#include <linux/export.h> +#include <linux/compiler.h> +#include <linux/dax.h> +#include <linux/fs.h> +#include <linux/sched/signal.h> +#include <linux/uaccess.h> +#include <linux/capability.h> +#include <linux/kernel_stat.h> +#include <linux/gfp.h> +#include <linux/mm.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/syscalls.h> +#include <linux/mman.h> +#include <linux/pagemap.h> +#include <linux/file.h> +#include <linux/uio.h> +#include <linux/error-injection.h> +#include <linux/hash.h> +#include <linux/writeback.h> +#include <linux/backing-dev.h> +#include <linux/pagevec.h> +#include <linux/security.h> +#include <linux/cpuset.h> +#include <linux/hugetlb.h> +#include <linux/memcontrol.h> +#include <linux/shmem_fs.h> +#include <linux/rmap.h> +#include <linux/delayacct.h> +#include <linux/psi.h> +#include <linux/ramfs.h> +#include <linux/page_idle.h> +#include <linux/migrate.h> +#include <linux/pipe_fs_i.h> +#include <linux/splice.h> +#include <asm/pgalloc.h> +#include <asm/tlbflush.h> +#include "internal.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/filemap.h> + +/* + * FIXME: remove all knowledge of the buffer layer from the core VM + */ +#include <linux/buffer_head.h> /* for try_to_free_buffers */ + +#include <asm/mman.h> + +#include "swap.h" + +/* + * Shared mappings implemented 30.11.1994. It's not fully working yet, + * though. + * + * Shared mappings now work. 15.8.1995 Bruno. + * + * finished 'unifying' the page and buffer cache and SMP-threaded the + * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> + * + * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> + */ + +/* + * Lock ordering: + * + * ->i_mmap_rwsem (truncate_pagecache) + * ->private_lock (__free_pte->block_dirty_folio) + * ->swap_lock (exclusive_swap_page, others) + * ->i_pages lock + * + * ->i_rwsem + * ->invalidate_lock (acquired by fs in truncate path) + * ->i_mmap_rwsem (truncate->unmap_mapping_range) + * + * ->mmap_lock + * ->i_mmap_rwsem + * ->page_table_lock or pte_lock (various, mainly in memory.c) + * ->i_pages lock (arch-dependent flush_dcache_mmap_lock) + * + * ->mmap_lock + * ->invalidate_lock (filemap_fault) + * ->lock_page (filemap_fault, access_process_vm) + * + * ->i_rwsem (generic_perform_write) + * ->mmap_lock (fault_in_readable->do_page_fault) + * + * bdi->wb.list_lock + * sb_lock (fs/fs-writeback.c) + * ->i_pages lock (__sync_single_inode) + * + * ->i_mmap_rwsem + * ->anon_vma.lock (vma_merge) + * + * ->anon_vma.lock + * ->page_table_lock or pte_lock (anon_vma_prepare and various) + * + * ->page_table_lock or pte_lock + * ->swap_lock (try_to_unmap_one) + * ->private_lock (try_to_unmap_one) + * ->i_pages lock (try_to_unmap_one) + * ->lruvec->lru_lock (follow_page->mark_page_accessed) + * ->lruvec->lru_lock (check_pte_range->isolate_lru_page) + * ->private_lock (page_remove_rmap->set_page_dirty) + * ->i_pages lock (page_remove_rmap->set_page_dirty) + * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) + * ->inode->i_lock (page_remove_rmap->set_page_dirty) + * ->memcg->move_lock (page_remove_rmap->folio_memcg_lock) + * bdi.wb->list_lock (zap_pte_range->set_page_dirty) + * ->inode->i_lock (zap_pte_range->set_page_dirty) + * ->private_lock (zap_pte_range->block_dirty_folio) + */ + +static void page_cache_delete(struct address_space *mapping, + struct folio *folio, void *shadow) +{ + XA_STATE(xas, &mapping->i_pages, folio->index); + long nr = 1; + + mapping_set_update(&xas, mapping); + + /* hugetlb pages are represented by a single entry in the xarray */ + if (!folio_test_hugetlb(folio)) { + xas_set_order(&xas, folio->index, folio_order(folio)); + nr = folio_nr_pages(folio); + } + + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + + xas_store(&xas, shadow); + xas_init_marks(&xas); + + folio->mapping = NULL; + /* Leave page->index set: truncation lookup relies upon it */ + mapping->nrpages -= nr; +} + +static void filemap_unaccount_folio(struct address_space *mapping, + struct folio *folio) +{ + long nr; + + VM_BUG_ON_FOLIO(folio_mapped(folio), folio); + if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) { + pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n", + current->comm, folio_pfn(folio)); + dump_page(&folio->page, "still mapped when deleted"); + dump_stack(); + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); + + if (mapping_exiting(mapping) && !folio_test_large(folio)) { + int mapcount = page_mapcount(&folio->page); + + if (folio_ref_count(folio) >= mapcount + 2) { + /* + * All vmas have already been torn down, so it's + * a good bet that actually the page is unmapped + * and we'd rather not leak it: if we're wrong, + * another bad page check should catch it later. + */ + page_mapcount_reset(&folio->page); + folio_ref_sub(folio, mapcount); + } + } + } + + /* hugetlb folios do not participate in page cache accounting. */ + if (folio_test_hugetlb(folio)) + return; + + nr = folio_nr_pages(folio); + + __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr); + if (folio_test_swapbacked(folio)) { + __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr); + if (folio_test_pmd_mappable(folio)) + __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr); + } else if (folio_test_pmd_mappable(folio)) { + __lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); + filemap_nr_thps_dec(mapping); + } + + /* + * At this point folio must be either written or cleaned by + * truncate. Dirty folio here signals a bug and loss of + * unwritten data - on ordinary filesystems. + * + * But it's harmless on in-memory filesystems like tmpfs; and can + * occur when a driver which did get_user_pages() sets page dirty + * before putting it, while the inode is being finally evicted. + * + * Below fixes dirty accounting after removing the folio entirely + * but leaves the dirty flag set: it has no effect for truncated + * folio and anyway will be cleared before returning folio to + * buddy allocator. + */ + if (WARN_ON_ONCE(folio_test_dirty(folio) && + mapping_can_writeback(mapping))) + folio_account_cleaned(folio, inode_to_wb(mapping->host)); +} + +/* + * Delete a page from the page cache and free it. Caller has to make + * sure the page is locked and that nobody else uses it - or that usage + * is safe. The caller must hold the i_pages lock. + */ +void __filemap_remove_folio(struct folio *folio, void *shadow) +{ + struct address_space *mapping = folio->mapping; + + trace_mm_filemap_delete_from_page_cache(folio); + filemap_unaccount_folio(mapping, folio); + page_cache_delete(mapping, folio, shadow); +} + +void filemap_free_folio(struct address_space *mapping, struct folio *folio) +{ + void (*free_folio)(struct folio *); + int refs = 1; + + free_folio = mapping->a_ops->free_folio; + if (free_folio) + free_folio(folio); + + if (folio_test_large(folio) && !folio_test_hugetlb(folio)) + refs = folio_nr_pages(folio); + folio_put_refs(folio, refs); +} + +/** + * filemap_remove_folio - Remove folio from page cache. + * @folio: The folio. + * + * This must be called only on folios that are locked and have been + * verified to be in the page cache. It will never put the folio into + * the free list because the caller has a reference on the page. + */ +void filemap_remove_folio(struct folio *folio) +{ + struct address_space *mapping = folio->mapping; + + BUG_ON(!folio_test_locked(folio)); + spin_lock(&mapping->host->i_lock); + xa_lock_irq(&mapping->i_pages); + __filemap_remove_folio(folio, NULL); + xa_unlock_irq(&mapping->i_pages); + if (mapping_shrinkable(mapping)) + inode_add_lru(mapping->host); + spin_unlock(&mapping->host->i_lock); + + filemap_free_folio(mapping, folio); +} + +/* + * page_cache_delete_batch - delete several folios from page cache + * @mapping: the mapping to which folios belong + * @fbatch: batch of folios to delete + * + * The function walks over mapping->i_pages and removes folios passed in + * @fbatch from the mapping. The function expects @fbatch to be sorted + * by page index and is optimised for it to be dense. + * It tolerates holes in @fbatch (mapping entries at those indices are not + * modified). + * + * The function expects the i_pages lock to be held. + */ +static void page_cache_delete_batch(struct address_space *mapping, + struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, fbatch->folios[0]->index); + long total_pages = 0; + int i = 0; + struct folio *folio; + + mapping_set_update(&xas, mapping); + xas_for_each(&xas, folio, ULONG_MAX) { + if (i >= folio_batch_count(fbatch)) + break; + + /* A swap/dax/shadow entry got inserted? Skip it. */ + if (xa_is_value(folio)) + continue; + /* + * A page got inserted in our range? Skip it. We have our + * pages locked so they are protected from being removed. + * If we see a page whose index is higher than ours, it + * means our page has been removed, which shouldn't be + * possible because we're holding the PageLock. + */ + if (folio != fbatch->folios[i]) { + VM_BUG_ON_FOLIO(folio->index > + fbatch->folios[i]->index, folio); + continue; + } + + WARN_ON_ONCE(!folio_test_locked(folio)); + + folio->mapping = NULL; + /* Leave folio->index set: truncation lookup relies on it */ + + i++; + xas_store(&xas, NULL); + total_pages += folio_nr_pages(folio); + } + mapping->nrpages -= total_pages; +} + +void delete_from_page_cache_batch(struct address_space *mapping, + struct folio_batch *fbatch) +{ + int i; + + if (!folio_batch_count(fbatch)) + return; + + spin_lock(&mapping->host->i_lock); + xa_lock_irq(&mapping->i_pages); + for (i = 0; i < folio_batch_count(fbatch); i++) { + struct folio *folio = fbatch->folios[i]; + + trace_mm_filemap_delete_from_page_cache(folio); + filemap_unaccount_folio(mapping, folio); + } + page_cache_delete_batch(mapping, fbatch); + xa_unlock_irq(&mapping->i_pages); + if (mapping_shrinkable(mapping)) + inode_add_lru(mapping->host); + spin_unlock(&mapping->host->i_lock); + + for (i = 0; i < folio_batch_count(fbatch); i++) + filemap_free_folio(mapping, fbatch->folios[i]); +} + +int filemap_check_errors(struct address_space *mapping) +{ + int ret = 0; + /* Check for outstanding write errors */ + if (test_bit(AS_ENOSPC, &mapping->flags) && + test_and_clear_bit(AS_ENOSPC, &mapping->flags)) + ret = -ENOSPC; + if (test_bit(AS_EIO, &mapping->flags) && + test_and_clear_bit(AS_EIO, &mapping->flags)) + ret = -EIO; + return ret; +} +EXPORT_SYMBOL(filemap_check_errors); + +static int filemap_check_and_keep_errors(struct address_space *mapping) +{ + /* Check for outstanding write errors */ + if (test_bit(AS_EIO, &mapping->flags)) + return -EIO; + if (test_bit(AS_ENOSPC, &mapping->flags)) + return -ENOSPC; + return 0; +} + +/** + * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range + * @mapping: address space structure to write + * @wbc: the writeback_control controlling the writeout + * + * Call writepages on the mapping using the provided wbc to control the + * writeout. + * + * Return: %0 on success, negative error code otherwise. + */ +int filemap_fdatawrite_wbc(struct address_space *mapping, + struct writeback_control *wbc) +{ + int ret; + + if (!mapping_can_writeback(mapping) || + !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) + return 0; + + wbc_attach_fdatawrite_inode(wbc, mapping->host); + ret = do_writepages(mapping, wbc); + wbc_detach_inode(wbc); + return ret; +} +EXPORT_SYMBOL(filemap_fdatawrite_wbc); + +/** + * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range + * @mapping: address space structure to write + * @start: offset in bytes where the range starts + * @end: offset in bytes where the range ends (inclusive) + * @sync_mode: enable synchronous operation + * + * Start writeback against all of a mapping's dirty pages that lie + * within the byte offsets <start, end> inclusive. + * + * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as + * opposed to a regular memory cleansing writeback. The difference between + * these two operations is that if a dirty page/buffer is encountered, it must + * be waited upon, and not just skipped over. + * + * Return: %0 on success, negative error code otherwise. + */ +int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, + loff_t end, int sync_mode) +{ + struct writeback_control wbc = { + .sync_mode = sync_mode, + .nr_to_write = LONG_MAX, + .range_start = start, + .range_end = end, + }; + + return filemap_fdatawrite_wbc(mapping, &wbc); +} + +static inline int __filemap_fdatawrite(struct address_space *mapping, + int sync_mode) +{ + return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); +} + +int filemap_fdatawrite(struct address_space *mapping) +{ + return __filemap_fdatawrite(mapping, WB_SYNC_ALL); +} +EXPORT_SYMBOL(filemap_fdatawrite); + +int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, + loff_t end) +{ + return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); +} +EXPORT_SYMBOL(filemap_fdatawrite_range); + +/** + * filemap_flush - mostly a non-blocking flush + * @mapping: target address_space + * + * This is a mostly non-blocking flush. Not suitable for data-integrity + * purposes - I/O may not be started against all dirty pages. + * + * Return: %0 on success, negative error code otherwise. + */ +int filemap_flush(struct address_space *mapping) +{ + return __filemap_fdatawrite(mapping, WB_SYNC_NONE); +} +EXPORT_SYMBOL(filemap_flush); + +/** + * filemap_range_has_page - check if a page exists in range. + * @mapping: address space within which to check + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Find at least one page in the range supplied, usually used to check if + * direct writing in this range will trigger a writeback. + * + * Return: %true if at least one page exists in the specified range, + * %false otherwise. + */ +bool filemap_range_has_page(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + struct folio *folio; + XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); + pgoff_t max = end_byte >> PAGE_SHIFT; + + if (end_byte < start_byte) + return false; + + rcu_read_lock(); + for (;;) { + folio = xas_find(&xas, max); + if (xas_retry(&xas, folio)) + continue; + /* Shadow entries don't count */ + if (xa_is_value(folio)) + continue; + /* + * We don't need to try to pin this page; we're about to + * release the RCU lock anyway. It is enough to know that + * there was a page here recently. + */ + break; + } + rcu_read_unlock(); + + return folio != NULL; +} +EXPORT_SYMBOL(filemap_range_has_page); + +static void __filemap_fdatawait_range(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + pgoff_t index = start_byte >> PAGE_SHIFT; + pgoff_t end = end_byte >> PAGE_SHIFT; + struct folio_batch fbatch; + unsigned nr_folios; + + folio_batch_init(&fbatch); + + while (index <= end) { + unsigned i; + + nr_folios = filemap_get_folios_tag(mapping, &index, end, + PAGECACHE_TAG_WRITEBACK, &fbatch); + + if (!nr_folios) + break; + + for (i = 0; i < nr_folios; i++) { + struct folio *folio = fbatch.folios[i]; + + folio_wait_writeback(folio); + folio_clear_error(folio); + } + folio_batch_release(&fbatch); + cond_resched(); + } +} + +/** + * filemap_fdatawait_range - wait for writeback to complete + * @mapping: address space structure to wait for + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Walk the list of under-writeback pages of the given address space + * in the given range and wait for all of them. Check error status of + * the address space and return it. + * + * Since the error status of the address space is cleared by this function, + * callers are responsible for checking the return value and handling and/or + * reporting the error. + * + * Return: error status of the address space. + */ +int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, + loff_t end_byte) +{ + __filemap_fdatawait_range(mapping, start_byte, end_byte); + return filemap_check_errors(mapping); +} +EXPORT_SYMBOL(filemap_fdatawait_range); + +/** + * filemap_fdatawait_range_keep_errors - wait for writeback to complete + * @mapping: address space structure to wait for + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Walk the list of under-writeback pages of the given address space in the + * given range and wait for all of them. Unlike filemap_fdatawait_range(), + * this function does not clear error status of the address space. + * + * Use this function if callers don't handle errors themselves. Expected + * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), + * fsfreeze(8) + */ +int filemap_fdatawait_range_keep_errors(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + __filemap_fdatawait_range(mapping, start_byte, end_byte); + return filemap_check_and_keep_errors(mapping); +} +EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors); + +/** + * file_fdatawait_range - wait for writeback to complete + * @file: file pointing to address space structure to wait for + * @start_byte: offset in bytes where the range starts + * @end_byte: offset in bytes where the range ends (inclusive) + * + * Walk the list of under-writeback pages of the address space that file + * refers to, in the given range and wait for all of them. Check error + * status of the address space vs. the file->f_wb_err cursor and return it. + * + * Since the error status of the file is advanced by this function, + * callers are responsible for checking the return value and handling and/or + * reporting the error. + * + * Return: error status of the address space vs. the file->f_wb_err cursor. + */ +int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte) +{ + struct address_space *mapping = file->f_mapping; + + __filemap_fdatawait_range(mapping, start_byte, end_byte); + return file_check_and_advance_wb_err(file); +} +EXPORT_SYMBOL(file_fdatawait_range); + +/** + * filemap_fdatawait_keep_errors - wait for writeback without clearing errors + * @mapping: address space structure to wait for + * + * Walk the list of under-writeback pages of the given address space + * and wait for all of them. Unlike filemap_fdatawait(), this function + * does not clear error status of the address space. + * + * Use this function if callers don't handle errors themselves. Expected + * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), + * fsfreeze(8) + * + * Return: error status of the address space. + */ +int filemap_fdatawait_keep_errors(struct address_space *mapping) +{ + __filemap_fdatawait_range(mapping, 0, LLONG_MAX); + return filemap_check_and_keep_errors(mapping); +} +EXPORT_SYMBOL(filemap_fdatawait_keep_errors); + +/* Returns true if writeback might be needed or already in progress. */ +static bool mapping_needs_writeback(struct address_space *mapping) +{ + return mapping->nrpages; +} + +bool filemap_range_has_writeback(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); + pgoff_t max = end_byte >> PAGE_SHIFT; + struct folio *folio; + + if (end_byte < start_byte) + return false; + + rcu_read_lock(); + xas_for_each(&xas, folio, max) { + if (xas_retry(&xas, folio)) + continue; + if (xa_is_value(folio)) + continue; + if (folio_test_dirty(folio) || folio_test_locked(folio) || + folio_test_writeback(folio)) + break; + } + rcu_read_unlock(); + return folio != NULL; +} +EXPORT_SYMBOL_GPL(filemap_range_has_writeback); + +/** + * filemap_write_and_wait_range - write out & wait on a file range + * @mapping: the address_space for the pages + * @lstart: offset in bytes where the range starts + * @lend: offset in bytes where the range ends (inclusive) + * + * Write out and wait upon file offsets lstart->lend, inclusive. + * + * Note that @lend is inclusive (describes the last byte to be written) so + * that this function can be used to write to the very end-of-file (end = -1). + * + * Return: error status of the address space. + */ +int filemap_write_and_wait_range(struct address_space *mapping, + loff_t lstart, loff_t lend) +{ + int err = 0, err2; + + if (lend < lstart) + return 0; + + if (mapping_needs_writeback(mapping)) { + err = __filemap_fdatawrite_range(mapping, lstart, lend, + WB_SYNC_ALL); + /* + * Even if the above returned error, the pages may be + * written partially (e.g. -ENOSPC), so we wait for it. + * But the -EIO is special case, it may indicate the worst + * thing (e.g. bug) happened, so we avoid waiting for it. + */ + if (err != -EIO) + __filemap_fdatawait_range(mapping, lstart, lend); + } + err2 = filemap_check_errors(mapping); + if (!err) + err = err2; + return err; +} +EXPORT_SYMBOL(filemap_write_and_wait_range); + +void __filemap_set_wb_err(struct address_space *mapping, int err) +{ + errseq_t eseq = errseq_set(&mapping->wb_err, err); + + trace_filemap_set_wb_err(mapping, eseq); +} +EXPORT_SYMBOL(__filemap_set_wb_err); + +/** + * file_check_and_advance_wb_err - report wb error (if any) that was previously + * and advance wb_err to current one + * @file: struct file on which the error is being reported + * + * When userland calls fsync (or something like nfsd does the equivalent), we + * want to report any writeback errors that occurred since the last fsync (or + * since the file was opened if there haven't been any). + * + * Grab the wb_err from the mapping. If it matches what we have in the file, + * then just quickly return 0. The file is all caught up. + * + * If it doesn't match, then take the mapping value, set the "seen" flag in + * it and try to swap it into place. If it works, or another task beat us + * to it with the new value, then update the f_wb_err and return the error + * portion. The error at this point must be reported via proper channels + * (a'la fsync, or NFS COMMIT operation, etc.). + * + * While we handle mapping->wb_err with atomic operations, the f_wb_err + * value is protected by the f_lock since we must ensure that it reflects + * the latest value swapped in for this file descriptor. + * + * Return: %0 on success, negative error code otherwise. + */ +int file_check_and_advance_wb_err(struct file *file) +{ + int err = 0; + errseq_t old = READ_ONCE(file->f_wb_err); + struct address_space *mapping = file->f_mapping; + + /* Locklessly handle the common case where nothing has changed */ + if (errseq_check(&mapping->wb_err, old)) { + /* Something changed, must use slow path */ + spin_lock(&file->f_lock); + old = file->f_wb_err; + err = errseq_check_and_advance(&mapping->wb_err, + &file->f_wb_err); + trace_file_check_and_advance_wb_err(file, old); + spin_unlock(&file->f_lock); + } + + /* + * We're mostly using this function as a drop in replacement for + * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect + * that the legacy code would have had on these flags. + */ + clear_bit(AS_EIO, &mapping->flags); + clear_bit(AS_ENOSPC, &mapping->flags); + return err; +} +EXPORT_SYMBOL(file_check_and_advance_wb_err); + +/** + * file_write_and_wait_range - write out & wait on a file range + * @file: file pointing to address_space with pages + * @lstart: offset in bytes where the range starts + * @lend: offset in bytes where the range ends (inclusive) + * + * Write out and wait upon file offsets lstart->lend, inclusive. + * + * Note that @lend is inclusive (describes the last byte to be written) so + * that this function can be used to write to the very end-of-file (end = -1). + * + * After writing out and waiting on the data, we check and advance the + * f_wb_err cursor to the latest value, and return any errors detected there. + * + * Return: %0 on success, negative error code otherwise. + */ +int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend) +{ + int err = 0, err2; + struct address_space *mapping = file->f_mapping; + + if (lend < lstart) + return 0; + + if (mapping_needs_writeback(mapping)) { + err = __filemap_fdatawrite_range(mapping, lstart, lend, + WB_SYNC_ALL); + /* See comment of filemap_write_and_wait() */ + if (err != -EIO) + __filemap_fdatawait_range(mapping, lstart, lend); + } + err2 = file_check_and_advance_wb_err(file); + if (!err) + err = err2; + return err; +} +EXPORT_SYMBOL(file_write_and_wait_range); + +/** + * replace_page_cache_folio - replace a pagecache folio with a new one + * @old: folio to be replaced + * @new: folio to replace with + * + * This function replaces a folio in the pagecache with a new one. On + * success it acquires the pagecache reference for the new folio and + * drops it for the old folio. Both the old and new folios must be + * locked. This function does not add the new folio to the LRU, the + * caller must do that. + * + * The remove + add is atomic. This function cannot fail. + */ +void replace_page_cache_folio(struct folio *old, struct folio *new) +{ + struct address_space *mapping = old->mapping; + void (*free_folio)(struct folio *) = mapping->a_ops->free_folio; + pgoff_t offset = old->index; + XA_STATE(xas, &mapping->i_pages, offset); + + VM_BUG_ON_FOLIO(!folio_test_locked(old), old); + VM_BUG_ON_FOLIO(!folio_test_locked(new), new); + VM_BUG_ON_FOLIO(new->mapping, new); + + folio_get(new); + new->mapping = mapping; + new->index = offset; + + mem_cgroup_migrate(old, new); + + xas_lock_irq(&xas); + xas_store(&xas, new); + + old->mapping = NULL; + /* hugetlb pages do not participate in page cache accounting. */ + if (!folio_test_hugetlb(old)) + __lruvec_stat_sub_folio(old, NR_FILE_PAGES); + if (!folio_test_hugetlb(new)) + __lruvec_stat_add_folio(new, NR_FILE_PAGES); + if (folio_test_swapbacked(old)) + __lruvec_stat_sub_folio(old, NR_SHMEM); + if (folio_test_swapbacked(new)) + __lruvec_stat_add_folio(new, NR_SHMEM); + xas_unlock_irq(&xas); + if (free_folio) + free_folio(old); + folio_put(old); +} +EXPORT_SYMBOL_GPL(replace_page_cache_folio); + +noinline int __filemap_add_folio(struct address_space *mapping, + struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp) +{ + XA_STATE(xas, &mapping->i_pages, index); + int huge = folio_test_hugetlb(folio); + bool charged = false; + long nr = 1; + + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio); + mapping_set_update(&xas, mapping); + + if (!huge) { + int error = mem_cgroup_charge(folio, NULL, gfp); + VM_BUG_ON_FOLIO(index & (folio_nr_pages(folio) - 1), folio); + if (error) + return error; + charged = true; + xas_set_order(&xas, index, folio_order(folio)); + nr = folio_nr_pages(folio); + } + + gfp &= GFP_RECLAIM_MASK; + folio_ref_add(folio, nr); + folio->mapping = mapping; + folio->index = xas.xa_index; + + do { + unsigned int order = xa_get_order(xas.xa, xas.xa_index); + void *entry, *old = NULL; + + if (order > folio_order(folio)) + xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index), + order, gfp); + xas_lock_irq(&xas); + xas_for_each_conflict(&xas, entry) { + old = entry; + if (!xa_is_value(entry)) { + xas_set_err(&xas, -EEXIST); + goto unlock; + } + } + + if (old) { + if (shadowp) + *shadowp = old; + /* entry may have been split before we acquired lock */ + order = xa_get_order(xas.xa, xas.xa_index); + if (order > folio_order(folio)) { + /* How to handle large swap entries? */ + BUG_ON(shmem_mapping(mapping)); + xas_split(&xas, old, order); + xas_reset(&xas); + } + } + + xas_store(&xas, folio); + if (xas_error(&xas)) + goto unlock; + + mapping->nrpages += nr; + + /* hugetlb pages do not participate in page cache accounting */ + if (!huge) { + __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr); + if (folio_test_pmd_mappable(folio)) + __lruvec_stat_mod_folio(folio, + NR_FILE_THPS, nr); + } +unlock: + xas_unlock_irq(&xas); + } while (xas_nomem(&xas, gfp)); + + if (xas_error(&xas)) + goto error; + + trace_mm_filemap_add_to_page_cache(folio); + return 0; +error: + if (charged) + mem_cgroup_uncharge(folio); + folio->mapping = NULL; + /* Leave page->index set: truncation relies upon it */ + folio_put_refs(folio, nr); + return xas_error(&xas); +} +ALLOW_ERROR_INJECTION(__filemap_add_folio, ERRNO); + +int filemap_add_folio(struct address_space *mapping, struct folio *folio, + pgoff_t index, gfp_t gfp) +{ + void *shadow = NULL; + int ret; + + __folio_set_locked(folio); + ret = __filemap_add_folio(mapping, folio, index, gfp, &shadow); + if (unlikely(ret)) + __folio_clear_locked(folio); + else { + /* + * The folio might have been evicted from cache only + * recently, in which case it should be activated like + * any other repeatedly accessed folio. + * The exception is folios getting rewritten; evicting other + * data from the working set, only to cache data that will + * get overwritten with something else, is a waste of memory. + */ + WARN_ON_ONCE(folio_test_active(folio)); + if (!(gfp & __GFP_WRITE) && shadow) + workingset_refault(folio, shadow); + folio_add_lru(folio); + } + return ret; +} +EXPORT_SYMBOL_GPL(filemap_add_folio); + +#ifdef CONFIG_NUMA +struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order) +{ + int n; + struct folio *folio; + + if (cpuset_do_page_mem_spread()) { + unsigned int cpuset_mems_cookie; + do { + cpuset_mems_cookie = read_mems_allowed_begin(); + n = cpuset_mem_spread_node(); + folio = __folio_alloc_node(gfp, order, n); + } while (!folio && read_mems_allowed_retry(cpuset_mems_cookie)); + + return folio; + } + return folio_alloc(gfp, order); +} +EXPORT_SYMBOL(filemap_alloc_folio); +#endif + +/* + * filemap_invalidate_lock_two - lock invalidate_lock for two mappings + * + * Lock exclusively invalidate_lock of any passed mapping that is not NULL. + * + * @mapping1: the first mapping to lock + * @mapping2: the second mapping to lock + */ +void filemap_invalidate_lock_two(struct address_space *mapping1, + struct address_space *mapping2) +{ + if (mapping1 > mapping2) + swap(mapping1, mapping2); + if (mapping1) + down_write(&mapping1->invalidate_lock); + if (mapping2 && mapping1 != mapping2) + down_write_nested(&mapping2->invalidate_lock, 1); +} +EXPORT_SYMBOL(filemap_invalidate_lock_two); + +/* + * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings + * + * Unlock exclusive invalidate_lock of any passed mapping that is not NULL. + * + * @mapping1: the first mapping to unlock + * @mapping2: the second mapping to unlock + */ +void filemap_invalidate_unlock_two(struct address_space *mapping1, + struct address_space *mapping2) +{ + if (mapping1) + up_write(&mapping1->invalidate_lock); + if (mapping2 && mapping1 != mapping2) + up_write(&mapping2->invalidate_lock); +} +EXPORT_SYMBOL(filemap_invalidate_unlock_two); + +/* + * In order to wait for pages to become available there must be + * waitqueues associated with pages. By using a hash table of + * waitqueues where the bucket discipline is to maintain all + * waiters on the same queue and wake all when any of the pages + * become available, and for the woken contexts to check to be + * sure the appropriate page became available, this saves space + * at a cost of "thundering herd" phenomena during rare hash + * collisions. + */ +#define PAGE_WAIT_TABLE_BITS 8 +#define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS) +static wait_queue_head_t folio_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned; + +static wait_queue_head_t *folio_waitqueue(struct folio *folio) +{ + return &folio_wait_table[hash_ptr(folio, PAGE_WAIT_TABLE_BITS)]; +} + +void __init pagecache_init(void) +{ + int i; + + for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++) + init_waitqueue_head(&folio_wait_table[i]); + + page_writeback_init(); +} + +/* + * The page wait code treats the "wait->flags" somewhat unusually, because + * we have multiple different kinds of waits, not just the usual "exclusive" + * one. + * + * We have: + * + * (a) no special bits set: + * + * We're just waiting for the bit to be released, and when a waker + * calls the wakeup function, we set WQ_FLAG_WOKEN and wake it up, + * and remove it from the wait queue. + * + * Simple and straightforward. + * + * (b) WQ_FLAG_EXCLUSIVE: + * + * The waiter is waiting to get the lock, and only one waiter should + * be woken up to avoid any thundering herd behavior. We'll set the + * WQ_FLAG_WOKEN bit, wake it up, and remove it from the wait queue. + * + * This is the traditional exclusive wait. + * + * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM: + * + * The waiter is waiting to get the bit, and additionally wants the + * lock to be transferred to it for fair lock behavior. If the lock + * cannot be taken, we stop walking the wait queue without waking + * the waiter. + * + * This is the "fair lock handoff" case, and in addition to setting + * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to let the waiter easily see + * that it now has the lock. + */ +static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg) +{ + unsigned int flags; + struct wait_page_key *key = arg; + struct wait_page_queue *wait_page + = container_of(wait, struct wait_page_queue, wait); + + if (!wake_page_match(wait_page, key)) + return 0; + + /* + * If it's a lock handoff wait, we get the bit for it, and + * stop walking (and do not wake it up) if we can't. + */ + flags = wait->flags; + if (flags & WQ_FLAG_EXCLUSIVE) { + if (test_bit(key->bit_nr, &key->folio->flags)) + return -1; + if (flags & WQ_FLAG_CUSTOM) { + if (test_and_set_bit(key->bit_nr, &key->folio->flags)) + return -1; + flags |= WQ_FLAG_DONE; + } + } + + /* + * We are holding the wait-queue lock, but the waiter that + * is waiting for this will be checking the flags without + * any locking. + * + * So update the flags atomically, and wake up the waiter + * afterwards to avoid any races. This store-release pairs + * with the load-acquire in folio_wait_bit_common(). + */ + smp_store_release(&wait->flags, flags | WQ_FLAG_WOKEN); + wake_up_state(wait->private, mode); + + /* + * Ok, we have successfully done what we're waiting for, + * and we can unconditionally remove the wait entry. + * + * Note that this pairs with the "finish_wait()" in the + * waiter, and has to be the absolute last thing we do. + * After this list_del_init(&wait->entry) the wait entry + * might be de-allocated and the process might even have + * exited. + */ + list_del_init_careful(&wait->entry); + return (flags & WQ_FLAG_EXCLUSIVE) != 0; +} + +static void folio_wake_bit(struct folio *folio, int bit_nr) +{ + wait_queue_head_t *q = folio_waitqueue(folio); + struct wait_page_key key; + unsigned long flags; + wait_queue_entry_t bookmark; + + key.folio = folio; + key.bit_nr = bit_nr; + key.page_match = 0; + + bookmark.flags = 0; + bookmark.private = NULL; + bookmark.func = NULL; + INIT_LIST_HEAD(&bookmark.entry); + + spin_lock_irqsave(&q->lock, flags); + __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark); + + while (bookmark.flags & WQ_FLAG_BOOKMARK) { + /* + * Take a breather from holding the lock, + * allow pages that finish wake up asynchronously + * to acquire the lock and remove themselves + * from wait queue + */ + spin_unlock_irqrestore(&q->lock, flags); + cpu_relax(); + spin_lock_irqsave(&q->lock, flags); + __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark); + } + + /* + * It's possible to miss clearing waiters here, when we woke our page + * waiters, but the hashed waitqueue has waiters for other pages on it. + * That's okay, it's a rare case. The next waker will clear it. + * + * Note that, depending on the page pool (buddy, hugetlb, ZONE_DEVICE, + * other), the flag may be cleared in the course of freeing the page; + * but that is not required for correctness. + */ + if (!waitqueue_active(q) || !key.page_match) + folio_clear_waiters(folio); + + spin_unlock_irqrestore(&q->lock, flags); +} + +static void folio_wake(struct folio *folio, int bit) +{ + if (!folio_test_waiters(folio)) + return; + folio_wake_bit(folio, bit); +} + +/* + * A choice of three behaviors for folio_wait_bit_common(): + */ +enum behavior { + EXCLUSIVE, /* Hold ref to page and take the bit when woken, like + * __folio_lock() waiting on then setting PG_locked. + */ + SHARED, /* Hold ref to page and check the bit when woken, like + * folio_wait_writeback() waiting on PG_writeback. + */ + DROP, /* Drop ref to page before wait, no check when woken, + * like folio_put_wait_locked() on PG_locked. + */ +}; + +/* + * Attempt to check (or get) the folio flag, and mark us done + * if successful. + */ +static inline bool folio_trylock_flag(struct folio *folio, int bit_nr, + struct wait_queue_entry *wait) +{ + if (wait->flags & WQ_FLAG_EXCLUSIVE) { + if (test_and_set_bit(bit_nr, &folio->flags)) + return false; + } else if (test_bit(bit_nr, &folio->flags)) + return false; + + wait->flags |= WQ_FLAG_WOKEN | WQ_FLAG_DONE; + return true; +} + +/* How many times do we accept lock stealing from under a waiter? */ +int sysctl_page_lock_unfairness = 5; + +static inline int folio_wait_bit_common(struct folio *folio, int bit_nr, + int state, enum behavior behavior) +{ + wait_queue_head_t *q = folio_waitqueue(folio); + int unfairness = sysctl_page_lock_unfairness; + struct wait_page_queue wait_page; + wait_queue_entry_t *wait = &wait_page.wait; + bool thrashing = false; + unsigned long pflags; + bool in_thrashing; + + if (bit_nr == PG_locked && + !folio_test_uptodate(folio) && folio_test_workingset(folio)) { + delayacct_thrashing_start(&in_thrashing); + psi_memstall_enter(&pflags); + thrashing = true; + } + + init_wait(wait); + wait->func = wake_page_function; + wait_page.folio = folio; + wait_page.bit_nr = bit_nr; + +repeat: + wait->flags = 0; + if (behavior == EXCLUSIVE) { + wait->flags = WQ_FLAG_EXCLUSIVE; + if (--unfairness < 0) + wait->flags |= WQ_FLAG_CUSTOM; + } + + /* + * Do one last check whether we can get the + * page bit synchronously. + * + * Do the folio_set_waiters() marking before that + * to let any waker we _just_ missed know they + * need to wake us up (otherwise they'll never + * even go to the slow case that looks at the + * page queue), and add ourselves to the wait + * queue if we need to sleep. + * + * This part needs to be done under the queue + * lock to avoid races. + */ + spin_lock_irq(&q->lock); + folio_set_waiters(folio); + if (!folio_trylock_flag(folio, bit_nr, wait)) + __add_wait_queue_entry_tail(q, wait); + spin_unlock_irq(&q->lock); + + /* + * From now on, all the logic will be based on + * the WQ_FLAG_WOKEN and WQ_FLAG_DONE flag, to + * see whether the page bit testing has already + * been done by the wake function. + * + * We can drop our reference to the folio. + */ + if (behavior == DROP) + folio_put(folio); + + /* + * Note that until the "finish_wait()", or until + * we see the WQ_FLAG_WOKEN flag, we need to + * be very careful with the 'wait->flags', because + * we may race with a waker that sets them. + */ + for (;;) { + unsigned int flags; + + set_current_state(state); + + /* Loop until we've been woken or interrupted */ + flags = smp_load_acquire(&wait->flags); + if (!(flags & WQ_FLAG_WOKEN)) { + if (signal_pending_state(state, current)) + break; + + io_schedule(); + continue; + } + + /* If we were non-exclusive, we're done */ + if (behavior != EXCLUSIVE) + break; + + /* If the waker got the lock for us, we're done */ + if (flags & WQ_FLAG_DONE) + break; + + /* + * Otherwise, if we're getting the lock, we need to + * try to get it ourselves. + * + * And if that fails, we'll have to retry this all. + */ + if (unlikely(test_and_set_bit(bit_nr, folio_flags(folio, 0)))) + goto repeat; + + wait->flags |= WQ_FLAG_DONE; + break; + } + + /* + * If a signal happened, this 'finish_wait()' may remove the last + * waiter from the wait-queues, but the folio waiters bit will remain + * set. That's ok. The next wakeup will take care of it, and trying + * to do it here would be difficult and prone to races. + */ + finish_wait(q, wait); + + if (thrashing) { + delayacct_thrashing_end(&in_thrashing); + psi_memstall_leave(&pflags); + } + + /* + * NOTE! The wait->flags weren't stable until we've done the + * 'finish_wait()', and we could have exited the loop above due + * to a signal, and had a wakeup event happen after the signal + * test but before the 'finish_wait()'. + * + * So only after the finish_wait() can we reliably determine + * if we got woken up or not, so we can now figure out the final + * return value based on that state without races. + * + * Also note that WQ_FLAG_WOKEN is sufficient for a non-exclusive + * waiter, but an exclusive one requires WQ_FLAG_DONE. + */ + if (behavior == EXCLUSIVE) + return wait->flags & WQ_FLAG_DONE ? 0 : -EINTR; + + return wait->flags & WQ_FLAG_WOKEN ? 0 : -EINTR; +} + +#ifdef CONFIG_MIGRATION +/** + * migration_entry_wait_on_locked - Wait for a migration entry to be removed + * @entry: migration swap entry. + * @ptl: already locked ptl. This function will drop the lock. + * + * Wait for a migration entry referencing the given page to be removed. This is + * equivalent to put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE) except + * this can be called without taking a reference on the page. Instead this + * should be called while holding the ptl for the migration entry referencing + * the page. + * + * Returns after unlocking the ptl. + * + * This follows the same logic as folio_wait_bit_common() so see the comments + * there. + */ +void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl) + __releases(ptl) +{ + struct wait_page_queue wait_page; + wait_queue_entry_t *wait = &wait_page.wait; + bool thrashing = false; + unsigned long pflags; + bool in_thrashing; + wait_queue_head_t *q; + struct folio *folio = page_folio(pfn_swap_entry_to_page(entry)); + + q = folio_waitqueue(folio); + if (!folio_test_uptodate(folio) && folio_test_workingset(folio)) { + delayacct_thrashing_start(&in_thrashing); + psi_memstall_enter(&pflags); + thrashing = true; + } + + init_wait(wait); + wait->func = wake_page_function; + wait_page.folio = folio; + wait_page.bit_nr = PG_locked; + wait->flags = 0; + + spin_lock_irq(&q->lock); + folio_set_waiters(folio); + if (!folio_trylock_flag(folio, PG_locked, wait)) + __add_wait_queue_entry_tail(q, wait); + spin_unlock_irq(&q->lock); + + /* + * If a migration entry exists for the page the migration path must hold + * a valid reference to the page, and it must take the ptl to remove the + * migration entry. So the page is valid until the ptl is dropped. + */ + spin_unlock(ptl); + + for (;;) { + unsigned int flags; + + set_current_state(TASK_UNINTERRUPTIBLE); + + /* Loop until we've been woken or interrupted */ + flags = smp_load_acquire(&wait->flags); + if (!(flags & WQ_FLAG_WOKEN)) { + if (signal_pending_state(TASK_UNINTERRUPTIBLE, current)) + break; + + io_schedule(); + continue; + } + break; + } + + finish_wait(q, wait); + + if (thrashing) { + delayacct_thrashing_end(&in_thrashing); + psi_memstall_leave(&pflags); + } +} +#endif + +void folio_wait_bit(struct folio *folio, int bit_nr) +{ + folio_wait_bit_common(folio, bit_nr, TASK_UNINTERRUPTIBLE, SHARED); +} +EXPORT_SYMBOL(folio_wait_bit); + +int folio_wait_bit_killable(struct folio *folio, int bit_nr) +{ + return folio_wait_bit_common(folio, bit_nr, TASK_KILLABLE, SHARED); +} +EXPORT_SYMBOL(folio_wait_bit_killable); + +/** + * folio_put_wait_locked - Drop a reference and wait for it to be unlocked + * @folio: The folio to wait for. + * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc). + * + * The caller should hold a reference on @folio. They expect the page to + * become unlocked relatively soon, but do not wish to hold up migration + * (for example) by holding the reference while waiting for the folio to + * come unlocked. After this function returns, the caller should not + * dereference @folio. + * + * Return: 0 if the folio was unlocked or -EINTR if interrupted by a signal. + */ +static int folio_put_wait_locked(struct folio *folio, int state) +{ + return folio_wait_bit_common(folio, PG_locked, state, DROP); +} + +/** + * folio_add_wait_queue - Add an arbitrary waiter to a folio's wait queue + * @folio: Folio defining the wait queue of interest + * @waiter: Waiter to add to the queue + * + * Add an arbitrary @waiter to the wait queue for the nominated @folio. + */ +void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter) +{ + wait_queue_head_t *q = folio_waitqueue(folio); + unsigned long flags; + + spin_lock_irqsave(&q->lock, flags); + __add_wait_queue_entry_tail(q, waiter); + folio_set_waiters(folio); + spin_unlock_irqrestore(&q->lock, flags); +} +EXPORT_SYMBOL_GPL(folio_add_wait_queue); + +#ifndef clear_bit_unlock_is_negative_byte + +/* + * PG_waiters is the high bit in the same byte as PG_lock. + * + * On x86 (and on many other architectures), we can clear PG_lock and + * test the sign bit at the same time. But if the architecture does + * not support that special operation, we just do this all by hand + * instead. + * + * The read of PG_waiters has to be after (or concurrently with) PG_locked + * being cleared, but a memory barrier should be unnecessary since it is + * in the same byte as PG_locked. + */ +static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem) +{ + clear_bit_unlock(nr, mem); + /* smp_mb__after_atomic(); */ + return test_bit(PG_waiters, mem); +} + +#endif + +/** + * folio_unlock - Unlock a locked folio. + * @folio: The folio. + * + * Unlocks the folio and wakes up any thread sleeping on the page lock. + * + * Context: May be called from interrupt or process context. May not be + * called from NMI context. + */ +void folio_unlock(struct folio *folio) +{ + /* Bit 7 allows x86 to check the byte's sign bit */ + BUILD_BUG_ON(PG_waiters != 7); + BUILD_BUG_ON(PG_locked > 7); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0))) + folio_wake_bit(folio, PG_locked); +} +EXPORT_SYMBOL(folio_unlock); + +/** + * folio_end_private_2 - Clear PG_private_2 and wake any waiters. + * @folio: The folio. + * + * Clear the PG_private_2 bit on a folio and wake up any sleepers waiting for + * it. The folio reference held for PG_private_2 being set is released. + * + * This is, for example, used when a netfs folio is being written to a local + * disk cache, thereby allowing writes to the cache for the same folio to be + * serialised. + */ +void folio_end_private_2(struct folio *folio) +{ + VM_BUG_ON_FOLIO(!folio_test_private_2(folio), folio); + clear_bit_unlock(PG_private_2, folio_flags(folio, 0)); + folio_wake_bit(folio, PG_private_2); + folio_put(folio); +} +EXPORT_SYMBOL(folio_end_private_2); + +/** + * folio_wait_private_2 - Wait for PG_private_2 to be cleared on a folio. + * @folio: The folio to wait on. + * + * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio. + */ +void folio_wait_private_2(struct folio *folio) +{ + while (folio_test_private_2(folio)) + folio_wait_bit(folio, PG_private_2); +} +EXPORT_SYMBOL(folio_wait_private_2); + +/** + * folio_wait_private_2_killable - Wait for PG_private_2 to be cleared on a folio. + * @folio: The folio to wait on. + * + * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio or until a + * fatal signal is received by the calling task. + * + * Return: + * - 0 if successful. + * - -EINTR if a fatal signal was encountered. + */ +int folio_wait_private_2_killable(struct folio *folio) +{ + int ret = 0; + + while (folio_test_private_2(folio)) { + ret = folio_wait_bit_killable(folio, PG_private_2); + if (ret < 0) + break; + } + + return ret; +} +EXPORT_SYMBOL(folio_wait_private_2_killable); + +/** + * folio_end_writeback - End writeback against a folio. + * @folio: The folio. + */ +void folio_end_writeback(struct folio *folio) +{ + /* + * folio_test_clear_reclaim() could be used here but it is an + * atomic operation and overkill in this particular case. Failing + * to shuffle a folio marked for immediate reclaim is too mild + * a gain to justify taking an atomic operation penalty at the + * end of every folio writeback. + */ + if (folio_test_reclaim(folio)) { + folio_clear_reclaim(folio); + folio_rotate_reclaimable(folio); + } + + /* + * Writeback does not hold a folio reference of its own, relying + * on truncation to wait for the clearing of PG_writeback. + * But here we must make sure that the folio is not freed and + * reused before the folio_wake(). + */ + folio_get(folio); + if (!__folio_end_writeback(folio)) + BUG(); + + smp_mb__after_atomic(); + folio_wake(folio, PG_writeback); + acct_reclaim_writeback(folio); + folio_put(folio); +} +EXPORT_SYMBOL(folio_end_writeback); + +/** + * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it. + * @folio: The folio to lock + */ +void __folio_lock(struct folio *folio) +{ + folio_wait_bit_common(folio, PG_locked, TASK_UNINTERRUPTIBLE, + EXCLUSIVE); +} +EXPORT_SYMBOL(__folio_lock); + +int __folio_lock_killable(struct folio *folio) +{ + return folio_wait_bit_common(folio, PG_locked, TASK_KILLABLE, + EXCLUSIVE); +} +EXPORT_SYMBOL_GPL(__folio_lock_killable); + +static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait) +{ + struct wait_queue_head *q = folio_waitqueue(folio); + int ret = 0; + + wait->folio = folio; + wait->bit_nr = PG_locked; + + spin_lock_irq(&q->lock); + __add_wait_queue_entry_tail(q, &wait->wait); + folio_set_waiters(folio); + ret = !folio_trylock(folio); + /* + * If we were successful now, we know we're still on the + * waitqueue as we're still under the lock. This means it's + * safe to remove and return success, we know the callback + * isn't going to trigger. + */ + if (!ret) + __remove_wait_queue(q, &wait->wait); + else + ret = -EIOCBQUEUED; + spin_unlock_irq(&q->lock); + return ret; +} + +/* + * Return values: + * 0 - folio is locked. + * non-zero - folio is not locked. + * mmap_lock or per-VMA lock has been released (mmap_read_unlock() or + * vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and + * FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held. + * + * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0 + * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed. + */ +vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf) +{ + unsigned int flags = vmf->flags; + + if (fault_flag_allow_retry_first(flags)) { + /* + * CAUTION! In this case, mmap_lock/per-VMA lock is not + * released even though returning VM_FAULT_RETRY. + */ + if (flags & FAULT_FLAG_RETRY_NOWAIT) + return VM_FAULT_RETRY; + + release_fault_lock(vmf); + if (flags & FAULT_FLAG_KILLABLE) + folio_wait_locked_killable(folio); + else + folio_wait_locked(folio); + return VM_FAULT_RETRY; + } + if (flags & FAULT_FLAG_KILLABLE) { + bool ret; + + ret = __folio_lock_killable(folio); + if (ret) { + release_fault_lock(vmf); + return VM_FAULT_RETRY; + } + } else { + __folio_lock(folio); + } + + return 0; +} + +/** + * page_cache_next_miss() - Find the next gap in the page cache. + * @mapping: Mapping. + * @index: Index. + * @max_scan: Maximum range to search. + * + * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the + * gap with the lowest index. + * + * This function may be called under the rcu_read_lock. However, this will + * not atomically search a snapshot of the cache at a single point in time. + * For example, if a gap is created at index 5, then subsequently a gap is + * created at index 10, page_cache_next_miss covering both indices may + * return 10 if called under the rcu_read_lock. + * + * Return: The index of the gap if found, otherwise an index outside the + * range specified (in which case 'return - index >= max_scan' will be true). + * In the rare case of index wrap-around, 0 will be returned. + */ +pgoff_t page_cache_next_miss(struct address_space *mapping, + pgoff_t index, unsigned long max_scan) +{ + XA_STATE(xas, &mapping->i_pages, index); + + while (max_scan--) { + void *entry = xas_next(&xas); + if (!entry || xa_is_value(entry)) + break; + if (xas.xa_index == 0) + break; + } + + return xas.xa_index; +} +EXPORT_SYMBOL(page_cache_next_miss); + +/** + * page_cache_prev_miss() - Find the previous gap in the page cache. + * @mapping: Mapping. + * @index: Index. + * @max_scan: Maximum range to search. + * + * Search the range [max(index - max_scan + 1, 0), index] for the + * gap with the highest index. + * + * This function may be called under the rcu_read_lock. However, this will + * not atomically search a snapshot of the cache at a single point in time. + * For example, if a gap is created at index 10, then subsequently a gap is + * created at index 5, page_cache_prev_miss() covering both indices may + * return 5 if called under the rcu_read_lock. + * + * Return: The index of the gap if found, otherwise an index outside the + * range specified (in which case 'index - return >= max_scan' will be true). + * In the rare case of wrap-around, ULONG_MAX will be returned. + */ +pgoff_t page_cache_prev_miss(struct address_space *mapping, + pgoff_t index, unsigned long max_scan) +{ + XA_STATE(xas, &mapping->i_pages, index); + + while (max_scan--) { + void *entry = xas_prev(&xas); + if (!entry || xa_is_value(entry)) + break; + if (xas.xa_index == ULONG_MAX) + break; + } + + return xas.xa_index; +} +EXPORT_SYMBOL(page_cache_prev_miss); + +/* + * Lockless page cache protocol: + * On the lookup side: + * 1. Load the folio from i_pages + * 2. Increment the refcount if it's not zero + * 3. If the folio is not found by xas_reload(), put the refcount and retry + * + * On the removal side: + * A. Freeze the page (by zeroing the refcount if nobody else has a reference) + * B. Remove the page from i_pages + * C. Return the page to the page allocator + * + * This means that any page may have its reference count temporarily + * increased by a speculative page cache (or fast GUP) lookup as it can + * be allocated by another user before the RCU grace period expires. + * Because the refcount temporarily acquired here may end up being the + * last refcount on the page, any page allocation must be freeable by + * folio_put(). + */ + +/* + * filemap_get_entry - Get a page cache entry. + * @mapping: the address_space to search + * @index: The page cache index. + * + * Looks up the page cache entry at @mapping & @index. If it is a folio, + * it is returned with an increased refcount. If it is a shadow entry + * of a previously evicted folio, or a swap entry from shmem/tmpfs, + * it is returned without further action. + * + * Return: The folio, swap or shadow entry, %NULL if nothing is found. + */ +void *filemap_get_entry(struct address_space *mapping, pgoff_t index) +{ + XA_STATE(xas, &mapping->i_pages, index); + struct folio *folio; + + rcu_read_lock(); +repeat: + xas_reset(&xas); + folio = xas_load(&xas); + if (xas_retry(&xas, folio)) + goto repeat; + /* + * A shadow entry of a recently evicted page, or a swap entry from + * shmem/tmpfs. Return it without attempting to raise page count. + */ + if (!folio || xa_is_value(folio)) + goto out; + + if (!folio_try_get_rcu(folio)) + goto repeat; + + if (unlikely(folio != xas_reload(&xas))) { + folio_put(folio); + goto repeat; + } +out: + rcu_read_unlock(); + + return folio; +} + +/** + * __filemap_get_folio - Find and get a reference to a folio. + * @mapping: The address_space to search. + * @index: The page index. + * @fgp_flags: %FGP flags modify how the folio is returned. + * @gfp: Memory allocation flags to use if %FGP_CREAT is specified. + * + * Looks up the page cache entry at @mapping & @index. + * + * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even + * if the %GFP flags specified for %FGP_CREAT are atomic. + * + * If this function returns a folio, it is returned with an increased refcount. + * + * Return: The found folio or an ERR_PTR() otherwise. + */ +struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, + fgf_t fgp_flags, gfp_t gfp) +{ + struct folio *folio; + +repeat: + folio = filemap_get_entry(mapping, index); + if (xa_is_value(folio)) + folio = NULL; + if (!folio) + goto no_page; + + if (fgp_flags & FGP_LOCK) { + if (fgp_flags & FGP_NOWAIT) { + if (!folio_trylock(folio)) { + folio_put(folio); + return ERR_PTR(-EAGAIN); + } + } else { + folio_lock(folio); + } + + /* Has the page been truncated? */ + if (unlikely(folio->mapping != mapping)) { + folio_unlock(folio); + folio_put(folio); + goto repeat; + } + VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio); + } + + if (fgp_flags & FGP_ACCESSED) + folio_mark_accessed(folio); + else if (fgp_flags & FGP_WRITE) { + /* Clear idle flag for buffer write */ + if (folio_test_idle(folio)) + folio_clear_idle(folio); + } + + if (fgp_flags & FGP_STABLE) + folio_wait_stable(folio); +no_page: + if (!folio && (fgp_flags & FGP_CREAT)) { + unsigned order = FGF_GET_ORDER(fgp_flags); + int err; + + if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping)) + gfp |= __GFP_WRITE; + if (fgp_flags & FGP_NOFS) + gfp &= ~__GFP_FS; + if (fgp_flags & FGP_NOWAIT) { + gfp &= ~GFP_KERNEL; + gfp |= GFP_NOWAIT | __GFP_NOWARN; + } + if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP)))) + fgp_flags |= FGP_LOCK; + + if (!mapping_large_folio_support(mapping)) + order = 0; + if (order > MAX_PAGECACHE_ORDER) + order = MAX_PAGECACHE_ORDER; + /* If we're not aligned, allocate a smaller folio */ + if (index & ((1UL << order) - 1)) + order = __ffs(index); + + do { + gfp_t alloc_gfp = gfp; + + err = -ENOMEM; + if (order == 1) + order = 0; + if (order > 0) + alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN; + folio = filemap_alloc_folio(alloc_gfp, order); + if (!folio) + continue; + + /* Init accessed so avoid atomic mark_page_accessed later */ + if (fgp_flags & FGP_ACCESSED) + __folio_set_referenced(folio); + + err = filemap_add_folio(mapping, folio, index, gfp); + if (!err) + break; + folio_put(folio); + folio = NULL; + } while (order-- > 0); + + if (err == -EEXIST) + goto repeat; + if (err) + return ERR_PTR(err); + /* + * filemap_add_folio locks the page, and for mmap + * we expect an unlocked page. + */ + if (folio && (fgp_flags & FGP_FOR_MMAP)) + folio_unlock(folio); + } + + if (!folio) + return ERR_PTR(-ENOENT); + return folio; +} +EXPORT_SYMBOL(__filemap_get_folio); + +static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max, + xa_mark_t mark) +{ + struct folio *folio; + +retry: + if (mark == XA_PRESENT) + folio = xas_find(xas, max); + else + folio = xas_find_marked(xas, max, mark); + + if (xas_retry(xas, folio)) + goto retry; + /* + * A shadow entry of a recently evicted page, a swap + * entry from shmem/tmpfs or a DAX entry. Return it + * without attempting to raise page count. + */ + if (!folio || xa_is_value(folio)) + return folio; + + if (!folio_try_get_rcu(folio)) + goto reset; + + if (unlikely(folio != xas_reload(xas))) { + folio_put(folio); + goto reset; + } + + return folio; +reset: + xas_reset(xas); + goto retry; +} + +/** + * find_get_entries - gang pagecache lookup + * @mapping: The address_space to search + * @start: The starting page cache index + * @end: The final page index (inclusive). + * @fbatch: Where the resulting entries are placed. + * @indices: The cache indices corresponding to the entries in @entries + * + * find_get_entries() will search for and return a batch of entries in + * the mapping. The entries are placed in @fbatch. find_get_entries() + * takes a reference on any actual folios it returns. + * + * The entries have ascending indexes. The indices may not be consecutive + * due to not-present entries or large folios. + * + * Any shadow entries of evicted folios, or swap entries from + * shmem/tmpfs, are included in the returned array. + * + * Return: The number of entries which were found. + */ +unsigned find_get_entries(struct address_space *mapping, pgoff_t *start, + pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices) +{ + XA_STATE(xas, &mapping->i_pages, *start); + struct folio *folio; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) { + indices[fbatch->nr] = xas.xa_index; + if (!folio_batch_add(fbatch, folio)) + break; + } + rcu_read_unlock(); + + if (folio_batch_count(fbatch)) { + unsigned long nr = 1; + int idx = folio_batch_count(fbatch) - 1; + + folio = fbatch->folios[idx]; + if (!xa_is_value(folio) && !folio_test_hugetlb(folio)) + nr = folio_nr_pages(folio); + *start = indices[idx] + nr; + } + return folio_batch_count(fbatch); +} + +/** + * find_lock_entries - Find a batch of pagecache entries. + * @mapping: The address_space to search. + * @start: The starting page cache index. + * @end: The final page index (inclusive). + * @fbatch: Where the resulting entries are placed. + * @indices: The cache indices of the entries in @fbatch. + * + * find_lock_entries() will return a batch of entries from @mapping. + * Swap, shadow and DAX entries are included. Folios are returned + * locked and with an incremented refcount. Folios which are locked + * by somebody else or under writeback are skipped. Folios which are + * partially outside the range are not returned. + * + * The entries have ascending indexes. The indices may not be consecutive + * due to not-present entries, large folios, folios which could not be + * locked or folios under writeback. + * + * Return: The number of entries which were found. + */ +unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start, + pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices) +{ + XA_STATE(xas, &mapping->i_pages, *start); + struct folio *folio; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, end, XA_PRESENT))) { + if (!xa_is_value(folio)) { + if (folio->index < *start) + goto put; + if (folio_next_index(folio) - 1 > end) + goto put; + if (!folio_trylock(folio)) + goto put; + if (folio->mapping != mapping || + folio_test_writeback(folio)) + goto unlock; + VM_BUG_ON_FOLIO(!folio_contains(folio, xas.xa_index), + folio); + } + indices[fbatch->nr] = xas.xa_index; + if (!folio_batch_add(fbatch, folio)) + break; + continue; +unlock: + folio_unlock(folio); +put: + folio_put(folio); + } + rcu_read_unlock(); + + if (folio_batch_count(fbatch)) { + unsigned long nr = 1; + int idx = folio_batch_count(fbatch) - 1; + + folio = fbatch->folios[idx]; + if (!xa_is_value(folio) && !folio_test_hugetlb(folio)) + nr = folio_nr_pages(folio); + *start = indices[idx] + nr; + } + return folio_batch_count(fbatch); +} + +/** + * filemap_get_folios - Get a batch of folios + * @mapping: The address_space to search + * @start: The starting page index + * @end: The final page index (inclusive) + * @fbatch: The batch to fill. + * + * Search for and return a batch of folios in the mapping starting at + * index @start and up to index @end (inclusive). The folios are returned + * in @fbatch with an elevated reference count. + * + * The first folio may start before @start; if it does, it will contain + * @start. The final folio may extend beyond @end; if it does, it will + * contain @end. The folios have ascending indices. There may be gaps + * between the folios if there are indices which have no folio in the + * page cache. If folios are added to or removed from the page cache + * while this is running, they may or may not be found by this call. + * + * Return: The number of folios which were found. + * We also update @start to index the next folio for the traversal. + */ +unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start, + pgoff_t end, struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, *start); + struct folio *folio; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) { + /* Skip over shadow, swap and DAX entries */ + if (xa_is_value(folio)) + continue; + if (!folio_batch_add(fbatch, folio)) { + unsigned long nr = folio_nr_pages(folio); + + if (folio_test_hugetlb(folio)) + nr = 1; + *start = folio->index + nr; + goto out; + } + } + + /* + * We come here when there is no page beyond @end. We take care to not + * overflow the index @start as it confuses some of the callers. This + * breaks the iteration when there is a page at index -1 but that is + * already broken anyway. + */ + if (end == (pgoff_t)-1) + *start = (pgoff_t)-1; + else + *start = end + 1; +out: + rcu_read_unlock(); + + return folio_batch_count(fbatch); +} +EXPORT_SYMBOL(filemap_get_folios); + +/** + * filemap_get_folios_contig - Get a batch of contiguous folios + * @mapping: The address_space to search + * @start: The starting page index + * @end: The final page index (inclusive) + * @fbatch: The batch to fill + * + * filemap_get_folios_contig() works exactly like filemap_get_folios(), + * except the returned folios are guaranteed to be contiguous. This may + * not return all contiguous folios if the batch gets filled up. + * + * Return: The number of folios found. + * Also update @start to be positioned for traversal of the next folio. + */ + +unsigned filemap_get_folios_contig(struct address_space *mapping, + pgoff_t *start, pgoff_t end, struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, *start); + unsigned long nr; + struct folio *folio; + + rcu_read_lock(); + + for (folio = xas_load(&xas); folio && xas.xa_index <= end; + folio = xas_next(&xas)) { + if (xas_retry(&xas, folio)) + continue; + /* + * If the entry has been swapped out, we can stop looking. + * No current caller is looking for DAX entries. + */ + if (xa_is_value(folio)) + goto update_start; + + if (!folio_try_get_rcu(folio)) + goto retry; + + if (unlikely(folio != xas_reload(&xas))) + goto put_folio; + + if (!folio_batch_add(fbatch, folio)) { + nr = folio_nr_pages(folio); + + if (folio_test_hugetlb(folio)) + nr = 1; + *start = folio->index + nr; + goto out; + } + continue; +put_folio: + folio_put(folio); + +retry: + xas_reset(&xas); + } + +update_start: + nr = folio_batch_count(fbatch); + + if (nr) { + folio = fbatch->folios[nr - 1]; + if (folio_test_hugetlb(folio)) + *start = folio->index + 1; + else + *start = folio_next_index(folio); + } +out: + rcu_read_unlock(); + return folio_batch_count(fbatch); +} +EXPORT_SYMBOL(filemap_get_folios_contig); + +/** + * filemap_get_folios_tag - Get a batch of folios matching @tag + * @mapping: The address_space to search + * @start: The starting page index + * @end: The final page index (inclusive) + * @tag: The tag index + * @fbatch: The batch to fill + * + * Same as filemap_get_folios(), but only returning folios tagged with @tag. + * + * Return: The number of folios found. + * Also update @start to index the next folio for traversal. + */ +unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start, + pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, *start); + struct folio *folio; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, end, tag)) != NULL) { + /* + * Shadow entries should never be tagged, but this iteration + * is lockless so there is a window for page reclaim to evict + * a page we saw tagged. Skip over it. + */ + if (xa_is_value(folio)) + continue; + if (!folio_batch_add(fbatch, folio)) { + unsigned long nr = folio_nr_pages(folio); + + if (folio_test_hugetlb(folio)) + nr = 1; + *start = folio->index + nr; + goto out; + } + } + /* + * We come here when there is no page beyond @end. We take care to not + * overflow the index @start as it confuses some of the callers. This + * breaks the iteration when there is a page at index -1 but that is + * already broke anyway. + */ + if (end == (pgoff_t)-1) + *start = (pgoff_t)-1; + else + *start = end + 1; +out: + rcu_read_unlock(); + + return folio_batch_count(fbatch); +} +EXPORT_SYMBOL(filemap_get_folios_tag); + +/* + * CD/DVDs are error prone. When a medium error occurs, the driver may fail + * a _large_ part of the i/o request. Imagine the worst scenario: + * + * ---R__________________________________________B__________ + * ^ reading here ^ bad block(assume 4k) + * + * read(R) => miss => readahead(R...B) => media error => frustrating retries + * => failing the whole request => read(R) => read(R+1) => + * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => + * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => + * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... + * + * It is going insane. Fix it by quickly scaling down the readahead size. + */ +static void shrink_readahead_size_eio(struct file_ra_state *ra) +{ + ra->ra_pages /= 4; +} + +/* + * filemap_get_read_batch - Get a batch of folios for read + * + * Get a batch of folios which represent a contiguous range of bytes in + * the file. No exceptional entries will be returned. If @index is in + * the middle of a folio, the entire folio will be returned. The last + * folio in the batch may have the readahead flag set or the uptodate flag + * clear so that the caller can take the appropriate action. + */ +static void filemap_get_read_batch(struct address_space *mapping, + pgoff_t index, pgoff_t max, struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, index); + struct folio *folio; + + rcu_read_lock(); + for (folio = xas_load(&xas); folio; folio = xas_next(&xas)) { + if (xas_retry(&xas, folio)) + continue; + if (xas.xa_index > max || xa_is_value(folio)) + break; + if (xa_is_sibling(folio)) + break; + if (!folio_try_get_rcu(folio)) + goto retry; + + if (unlikely(folio != xas_reload(&xas))) + goto put_folio; + + if (!folio_batch_add(fbatch, folio)) + break; + if (!folio_test_uptodate(folio)) + break; + if (folio_test_readahead(folio)) + break; + xas_advance(&xas, folio_next_index(folio) - 1); + continue; +put_folio: + folio_put(folio); +retry: + xas_reset(&xas); + } + rcu_read_unlock(); +} + +static int filemap_read_folio(struct file *file, filler_t filler, + struct folio *folio) +{ + bool workingset = folio_test_workingset(folio); + unsigned long pflags; + int error; + + /* + * A previous I/O error may have been due to temporary failures, + * eg. multipath errors. PG_error will be set again if read_folio + * fails. + */ + folio_clear_error(folio); + + /* Start the actual read. The read will unlock the page. */ + if (unlikely(workingset)) + psi_memstall_enter(&pflags); + error = filler(file, folio); + if (unlikely(workingset)) + psi_memstall_leave(&pflags); + if (error) + return error; + + error = folio_wait_locked_killable(folio); + if (error) + return error; + if (folio_test_uptodate(folio)) + return 0; + if (file) + shrink_readahead_size_eio(&file->f_ra); + return -EIO; +} + +static bool filemap_range_uptodate(struct address_space *mapping, + loff_t pos, size_t count, struct folio *folio, + bool need_uptodate) +{ + if (folio_test_uptodate(folio)) + return true; + /* pipes can't handle partially uptodate pages */ + if (need_uptodate) + return false; + if (!mapping->a_ops->is_partially_uptodate) + return false; + if (mapping->host->i_blkbits >= folio_shift(folio)) + return false; + + if (folio_pos(folio) > pos) { + count -= folio_pos(folio) - pos; + pos = 0; + } else { + pos -= folio_pos(folio); + } + + return mapping->a_ops->is_partially_uptodate(folio, pos, count); +} + +static int filemap_update_page(struct kiocb *iocb, + struct address_space *mapping, size_t count, + struct folio *folio, bool need_uptodate) +{ + int error; + + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!filemap_invalidate_trylock_shared(mapping)) + return -EAGAIN; + } else { + filemap_invalidate_lock_shared(mapping); + } + + if (!folio_trylock(folio)) { + error = -EAGAIN; + if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) + goto unlock_mapping; + if (!(iocb->ki_flags & IOCB_WAITQ)) { + filemap_invalidate_unlock_shared(mapping); + /* + * This is where we usually end up waiting for a + * previously submitted readahead to finish. + */ + folio_put_wait_locked(folio, TASK_KILLABLE); + return AOP_TRUNCATED_PAGE; + } + error = __folio_lock_async(folio, iocb->ki_waitq); + if (error) + goto unlock_mapping; + } + + error = AOP_TRUNCATED_PAGE; + if (!folio->mapping) + goto unlock; + + error = 0; + if (filemap_range_uptodate(mapping, iocb->ki_pos, count, folio, + need_uptodate)) + goto unlock; + + error = -EAGAIN; + if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) + goto unlock; + + error = filemap_read_folio(iocb->ki_filp, mapping->a_ops->read_folio, + folio); + goto unlock_mapping; +unlock: + folio_unlock(folio); +unlock_mapping: + filemap_invalidate_unlock_shared(mapping); + if (error == AOP_TRUNCATED_PAGE) + folio_put(folio); + return error; +} + +static int filemap_create_folio(struct file *file, + struct address_space *mapping, pgoff_t index, + struct folio_batch *fbatch) +{ + struct folio *folio; + int error; + + folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0); + if (!folio) + return -ENOMEM; + + /* + * Protect against truncate / hole punch. Grabbing invalidate_lock + * here assures we cannot instantiate and bring uptodate new + * pagecache folios after evicting page cache during truncate + * and before actually freeing blocks. Note that we could + * release invalidate_lock after inserting the folio into + * the page cache as the locked folio would then be enough to + * synchronize with hole punching. But there are code paths + * such as filemap_update_page() filling in partially uptodate + * pages or ->readahead() that need to hold invalidate_lock + * while mapping blocks for IO so let's hold the lock here as + * well to keep locking rules simple. + */ + filemap_invalidate_lock_shared(mapping); + error = filemap_add_folio(mapping, folio, index, + mapping_gfp_constraint(mapping, GFP_KERNEL)); + if (error == -EEXIST) + error = AOP_TRUNCATED_PAGE; + if (error) + goto error; + + error = filemap_read_folio(file, mapping->a_ops->read_folio, folio); + if (error) + goto error; + + filemap_invalidate_unlock_shared(mapping); + folio_batch_add(fbatch, folio); + return 0; +error: + filemap_invalidate_unlock_shared(mapping); + folio_put(folio); + return error; +} + +static int filemap_readahead(struct kiocb *iocb, struct file *file, + struct address_space *mapping, struct folio *folio, + pgoff_t last_index) +{ + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, folio->index); + + if (iocb->ki_flags & IOCB_NOIO) + return -EAGAIN; + page_cache_async_ra(&ractl, folio, last_index - folio->index); + return 0; +} + +static int filemap_get_pages(struct kiocb *iocb, size_t count, + struct folio_batch *fbatch, bool need_uptodate) +{ + struct file *filp = iocb->ki_filp; + struct address_space *mapping = filp->f_mapping; + struct file_ra_state *ra = &filp->f_ra; + pgoff_t index = iocb->ki_pos >> PAGE_SHIFT; + pgoff_t last_index; + struct folio *folio; + int err = 0; + + /* "last_index" is the index of the page beyond the end of the read */ + last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE); +retry: + if (fatal_signal_pending(current)) + return -EINTR; + + filemap_get_read_batch(mapping, index, last_index - 1, fbatch); + if (!folio_batch_count(fbatch)) { + if (iocb->ki_flags & IOCB_NOIO) + return -EAGAIN; + page_cache_sync_readahead(mapping, ra, filp, index, + last_index - index); + filemap_get_read_batch(mapping, index, last_index - 1, fbatch); + } + if (!folio_batch_count(fbatch)) { + if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) + return -EAGAIN; + err = filemap_create_folio(filp, mapping, + iocb->ki_pos >> PAGE_SHIFT, fbatch); + if (err == AOP_TRUNCATED_PAGE) + goto retry; + return err; + } + + folio = fbatch->folios[folio_batch_count(fbatch) - 1]; + if (folio_test_readahead(folio)) { + err = filemap_readahead(iocb, filp, mapping, folio, last_index); + if (err) + goto err; + } + if (!folio_test_uptodate(folio)) { + if ((iocb->ki_flags & IOCB_WAITQ) && + folio_batch_count(fbatch) > 1) + iocb->ki_flags |= IOCB_NOWAIT; + err = filemap_update_page(iocb, mapping, count, folio, + need_uptodate); + if (err) + goto err; + } + + return 0; +err: + if (err < 0) + folio_put(folio); + if (likely(--fbatch->nr)) + return 0; + if (err == AOP_TRUNCATED_PAGE) + goto retry; + return err; +} + +static inline bool pos_same_folio(loff_t pos1, loff_t pos2, struct folio *folio) +{ + unsigned int shift = folio_shift(folio); + + return (pos1 >> shift == pos2 >> shift); +} + +/** + * filemap_read - Read data from the page cache. + * @iocb: The iocb to read. + * @iter: Destination for the data. + * @already_read: Number of bytes already read by the caller. + * + * Copies data from the page cache. If the data is not currently present, + * uses the readahead and read_folio address_space operations to fetch it. + * + * Return: Total number of bytes copied, including those already read by + * the caller. If an error happens before any bytes are copied, returns + * a negative error number. + */ +ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter, + ssize_t already_read) +{ + struct file *filp = iocb->ki_filp; + struct file_ra_state *ra = &filp->f_ra; + struct address_space *mapping = filp->f_mapping; + struct inode *inode = mapping->host; + struct folio_batch fbatch; + int i, error = 0; + bool writably_mapped; + loff_t isize, end_offset; + loff_t last_pos = ra->prev_pos; + + if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes)) + return 0; + if (unlikely(!iov_iter_count(iter))) + return 0; + + iov_iter_truncate(iter, inode->i_sb->s_maxbytes); + folio_batch_init(&fbatch); + + do { + cond_resched(); + + /* + * If we've already successfully copied some data, then we + * can no longer safely return -EIOCBQUEUED. Hence mark + * an async read NOWAIT at that point. + */ + if ((iocb->ki_flags & IOCB_WAITQ) && already_read) + iocb->ki_flags |= IOCB_NOWAIT; + + if (unlikely(iocb->ki_pos >= i_size_read(inode))) + break; + + error = filemap_get_pages(iocb, iter->count, &fbatch, false); + if (error < 0) + break; + + /* + * i_size must be checked after we know the pages are Uptodate. + * + * Checking i_size after the check allows us to calculate + * the correct value for "nr", which means the zero-filled + * part of the page is not copied back to userspace (unless + * another truncate extends the file - this is desired though). + */ + isize = i_size_read(inode); + if (unlikely(iocb->ki_pos >= isize)) + goto put_folios; + end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count); + + /* + * Pairs with a barrier in + * block_write_end()->mark_buffer_dirty() or other page + * dirtying routines like iomap_write_end() to ensure + * changes to page contents are visible before we see + * increased inode size. + */ + smp_rmb(); + + /* + * Once we start copying data, we don't want to be touching any + * cachelines that might be contended: + */ + writably_mapped = mapping_writably_mapped(mapping); + + /* + * When a read accesses the same folio several times, only + * mark it as accessed the first time. + */ + if (!pos_same_folio(iocb->ki_pos, last_pos - 1, + fbatch.folios[0])) + folio_mark_accessed(fbatch.folios[0]); + + for (i = 0; i < folio_batch_count(&fbatch); i++) { + struct folio *folio = fbatch.folios[i]; + size_t fsize = folio_size(folio); + size_t offset = iocb->ki_pos & (fsize - 1); + size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos, + fsize - offset); + size_t copied; + + if (end_offset < folio_pos(folio)) + break; + if (i > 0) + folio_mark_accessed(folio); + /* + * If users can be writing to this folio using arbitrary + * virtual addresses, take care of potential aliasing + * before reading the folio on the kernel side. + */ + if (writably_mapped) + flush_dcache_folio(folio); + + copied = copy_folio_to_iter(folio, offset, bytes, iter); + + already_read += copied; + iocb->ki_pos += copied; + last_pos = iocb->ki_pos; + + if (copied < bytes) { + error = -EFAULT; + break; + } + } +put_folios: + for (i = 0; i < folio_batch_count(&fbatch); i++) + folio_put(fbatch.folios[i]); + folio_batch_init(&fbatch); + } while (iov_iter_count(iter) && iocb->ki_pos < isize && !error); + + file_accessed(filp); + ra->prev_pos = last_pos; + return already_read ? already_read : error; +} +EXPORT_SYMBOL_GPL(filemap_read); + +int kiocb_write_and_wait(struct kiocb *iocb, size_t count) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + loff_t pos = iocb->ki_pos; + loff_t end = pos + count - 1; + + if (iocb->ki_flags & IOCB_NOWAIT) { + if (filemap_range_needs_writeback(mapping, pos, end)) + return -EAGAIN; + return 0; + } + + return filemap_write_and_wait_range(mapping, pos, end); +} + +int kiocb_invalidate_pages(struct kiocb *iocb, size_t count) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + loff_t pos = iocb->ki_pos; + loff_t end = pos + count - 1; + int ret; + + if (iocb->ki_flags & IOCB_NOWAIT) { + /* we could block if there are any pages in the range */ + if (filemap_range_has_page(mapping, pos, end)) + return -EAGAIN; + } else { + ret = filemap_write_and_wait_range(mapping, pos, end); + if (ret) + return ret; + } + + /* + * After a write we want buffered reads to be sure to go to disk to get + * the new data. We invalidate clean cached page from the region we're + * about to write. We do this *before* the write so that we can return + * without clobbering -EIOCBQUEUED from ->direct_IO(). + */ + return invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, + end >> PAGE_SHIFT); +} + +/** + * generic_file_read_iter - generic filesystem read routine + * @iocb: kernel I/O control block + * @iter: destination for the data read + * + * This is the "read_iter()" routine for all filesystems + * that can use the page cache directly. + * + * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall + * be returned when no data can be read without waiting for I/O requests + * to complete; it doesn't prevent readahead. + * + * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O + * requests shall be made for the read or for readahead. When no data + * can be read, -EAGAIN shall be returned. When readahead would be + * triggered, a partial, possibly empty read shall be returned. + * + * Return: + * * number of bytes copied, even for partial reads + * * negative error code (or 0 if IOCB_NOIO) if nothing was read + */ +ssize_t +generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + size_t count = iov_iter_count(iter); + ssize_t retval = 0; + + if (!count) + return 0; /* skip atime */ + + if (iocb->ki_flags & IOCB_DIRECT) { + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + + retval = kiocb_write_and_wait(iocb, count); + if (retval < 0) + return retval; + file_accessed(file); + + retval = mapping->a_ops->direct_IO(iocb, iter); + if (retval >= 0) { + iocb->ki_pos += retval; + count -= retval; + } + if (retval != -EIOCBQUEUED) + iov_iter_revert(iter, count - iov_iter_count(iter)); + + /* + * Btrfs can have a short DIO read if we encounter + * compressed extents, so if there was an error, or if + * we've already read everything we wanted to, or if + * there was a short read because we hit EOF, go ahead + * and return. Otherwise fallthrough to buffered io for + * the rest of the read. Buffered reads will not work for + * DAX files, so don't bother trying. + */ + if (retval < 0 || !count || IS_DAX(inode)) + return retval; + if (iocb->ki_pos >= i_size_read(inode)) + return retval; + } + + return filemap_read(iocb, iter, retval); +} +EXPORT_SYMBOL(generic_file_read_iter); + +/* + * Splice subpages from a folio into a pipe. + */ +size_t splice_folio_into_pipe(struct pipe_inode_info *pipe, + struct folio *folio, loff_t fpos, size_t size) +{ + struct page *page; + size_t spliced = 0, offset = offset_in_folio(folio, fpos); + + page = folio_page(folio, offset / PAGE_SIZE); + size = min(size, folio_size(folio) - offset); + offset %= PAGE_SIZE; + + while (spliced < size && + !pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { + struct pipe_buffer *buf = pipe_head_buf(pipe); + size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced); + + *buf = (struct pipe_buffer) { + .ops = &page_cache_pipe_buf_ops, + .page = page, + .offset = offset, + .len = part, + }; + folio_get(folio); + pipe->head++; + page++; + spliced += part; + offset = 0; + } + + return spliced; +} + +/** + * filemap_splice_read - Splice data from a file's pagecache into a pipe + * @in: The file to read from + * @ppos: Pointer to the file position to read from + * @pipe: The pipe to splice into + * @len: The amount to splice + * @flags: The SPLICE_F_* flags + * + * This function gets folios from a file's pagecache and splices them into the + * pipe. Readahead will be called as necessary to fill more folios. This may + * be used for blockdevs also. + * + * Return: On success, the number of bytes read will be returned and *@ppos + * will be updated if appropriate; 0 will be returned if there is no more data + * to be read; -EAGAIN will be returned if the pipe had no space, and some + * other negative error code will be returned on error. A short read may occur + * if the pipe has insufficient space, we reach the end of the data or we hit a + * hole. + */ +ssize_t filemap_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags) +{ + struct folio_batch fbatch; + struct kiocb iocb; + size_t total_spliced = 0, used, npages; + loff_t isize, end_offset; + bool writably_mapped; + int i, error = 0; + + if (unlikely(*ppos >= in->f_mapping->host->i_sb->s_maxbytes)) + return 0; + + init_sync_kiocb(&iocb, in); + iocb.ki_pos = *ppos; + + /* Work out how much data we can actually add into the pipe */ + used = pipe_occupancy(pipe->head, pipe->tail); + npages = max_t(ssize_t, pipe->max_usage - used, 0); + len = min_t(size_t, len, npages * PAGE_SIZE); + + folio_batch_init(&fbatch); + + do { + cond_resched(); + + if (*ppos >= i_size_read(in->f_mapping->host)) + break; + + iocb.ki_pos = *ppos; + error = filemap_get_pages(&iocb, len, &fbatch, true); + if (error < 0) + break; + + /* + * i_size must be checked after we know the pages are Uptodate. + * + * Checking i_size after the check allows us to calculate + * the correct value for "nr", which means the zero-filled + * part of the page is not copied back to userspace (unless + * another truncate extends the file - this is desired though). + */ + isize = i_size_read(in->f_mapping->host); + if (unlikely(*ppos >= isize)) + break; + end_offset = min_t(loff_t, isize, *ppos + len); + + /* + * Once we start copying data, we don't want to be touching any + * cachelines that might be contended: + */ + writably_mapped = mapping_writably_mapped(in->f_mapping); + + for (i = 0; i < folio_batch_count(&fbatch); i++) { + struct folio *folio = fbatch.folios[i]; + size_t n; + + if (folio_pos(folio) >= end_offset) + goto out; + folio_mark_accessed(folio); + + /* + * If users can be writing to this folio using arbitrary + * virtual addresses, take care of potential aliasing + * before reading the folio on the kernel side. + */ + if (writably_mapped) + flush_dcache_folio(folio); + + n = min_t(loff_t, len, isize - *ppos); + n = splice_folio_into_pipe(pipe, folio, *ppos, n); + if (!n) + goto out; + len -= n; + total_spliced += n; + *ppos += n; + in->f_ra.prev_pos = *ppos; + if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) + goto out; + } + + folio_batch_release(&fbatch); + } while (len); + +out: + folio_batch_release(&fbatch); + file_accessed(in); + + return total_spliced ? total_spliced : error; +} +EXPORT_SYMBOL(filemap_splice_read); + +static inline loff_t folio_seek_hole_data(struct xa_state *xas, + struct address_space *mapping, struct folio *folio, + loff_t start, loff_t end, bool seek_data) +{ + const struct address_space_operations *ops = mapping->a_ops; + size_t offset, bsz = i_blocksize(mapping->host); + + if (xa_is_value(folio) || folio_test_uptodate(folio)) + return seek_data ? start : end; + if (!ops->is_partially_uptodate) + return seek_data ? end : start; + + xas_pause(xas); + rcu_read_unlock(); + folio_lock(folio); + if (unlikely(folio->mapping != mapping)) + goto unlock; + + offset = offset_in_folio(folio, start) & ~(bsz - 1); + + do { + if (ops->is_partially_uptodate(folio, offset, bsz) == + seek_data) + break; + start = (start + bsz) & ~(bsz - 1); + offset += bsz; + } while (offset < folio_size(folio)); +unlock: + folio_unlock(folio); + rcu_read_lock(); + return start; +} + +static inline size_t seek_folio_size(struct xa_state *xas, struct folio *folio) +{ + if (xa_is_value(folio)) + return PAGE_SIZE << xa_get_order(xas->xa, xas->xa_index); + return folio_size(folio); +} + +/** + * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache. + * @mapping: Address space to search. + * @start: First byte to consider. + * @end: Limit of search (exclusive). + * @whence: Either SEEK_HOLE or SEEK_DATA. + * + * If the page cache knows which blocks contain holes and which blocks + * contain data, your filesystem can use this function to implement + * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are + * entirely memory-based such as tmpfs, and filesystems which support + * unwritten extents. + * + * Return: The requested offset on success, or -ENXIO if @whence specifies + * SEEK_DATA and there is no data after @start. There is an implicit hole + * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start + * and @end contain data. + */ +loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start, + loff_t end, int whence) +{ + XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT); + pgoff_t max = (end - 1) >> PAGE_SHIFT; + bool seek_data = (whence == SEEK_DATA); + struct folio *folio; + + if (end <= start) + return -ENXIO; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, max, XA_PRESENT))) { + loff_t pos = (u64)xas.xa_index << PAGE_SHIFT; + size_t seek_size; + + if (start < pos) { + if (!seek_data) + goto unlock; + start = pos; + } + + seek_size = seek_folio_size(&xas, folio); + pos = round_up((u64)pos + 1, seek_size); + start = folio_seek_hole_data(&xas, mapping, folio, start, pos, + seek_data); + if (start < pos) + goto unlock; + if (start >= end) + break; + if (seek_size > PAGE_SIZE) + xas_set(&xas, pos >> PAGE_SHIFT); + if (!xa_is_value(folio)) + folio_put(folio); + } + if (seek_data) + start = -ENXIO; +unlock: + rcu_read_unlock(); + if (folio && !xa_is_value(folio)) + folio_put(folio); + if (start > end) + return end; + return start; +} + +#ifdef CONFIG_MMU +#define MMAP_LOTSAMISS (100) +/* + * lock_folio_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock + * @vmf - the vm_fault for this fault. + * @folio - the folio to lock. + * @fpin - the pointer to the file we may pin (or is already pinned). + * + * This works similar to lock_folio_or_retry in that it can drop the + * mmap_lock. It differs in that it actually returns the folio locked + * if it returns 1 and 0 if it couldn't lock the folio. If we did have + * to drop the mmap_lock then fpin will point to the pinned file and + * needs to be fput()'ed at a later point. + */ +static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio, + struct file **fpin) +{ + if (folio_trylock(folio)) + return 1; + + /* + * NOTE! This will make us return with VM_FAULT_RETRY, but with + * the mmap_lock still held. That's how FAULT_FLAG_RETRY_NOWAIT + * is supposed to work. We have way too many special cases.. + */ + if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) + return 0; + + *fpin = maybe_unlock_mmap_for_io(vmf, *fpin); + if (vmf->flags & FAULT_FLAG_KILLABLE) { + if (__folio_lock_killable(folio)) { + /* + * We didn't have the right flags to drop the mmap_lock, + * but all fault_handlers only check for fatal signals + * if we return VM_FAULT_RETRY, so we need to drop the + * mmap_lock here and return 0 if we don't have a fpin. + */ + if (*fpin == NULL) + mmap_read_unlock(vmf->vma->vm_mm); + return 0; + } + } else + __folio_lock(folio); + + return 1; +} + +/* + * Synchronous readahead happens when we don't even find a page in the page + * cache at all. We don't want to perform IO under the mmap sem, so if we have + * to drop the mmap sem we return the file that was pinned in order for us to do + * that. If we didn't pin a file then we return NULL. The file that is + * returned needs to be fput()'ed when we're done with it. + */ +static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) +{ + struct file *file = vmf->vma->vm_file; + struct file_ra_state *ra = &file->f_ra; + struct address_space *mapping = file->f_mapping; + DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff); + struct file *fpin = NULL; + unsigned long vm_flags = vmf->vma->vm_flags; + unsigned int mmap_miss; + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + /* Use the readahead code, even if readahead is disabled */ + if (vm_flags & VM_HUGEPAGE) { + fpin = maybe_unlock_mmap_for_io(vmf, fpin); + ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1); + ra->size = HPAGE_PMD_NR; + /* + * Fetch two PMD folios, so we get the chance to actually + * readahead, unless we've been told not to. + */ + if (!(vm_flags & VM_RAND_READ)) + ra->size *= 2; + ra->async_size = HPAGE_PMD_NR; + page_cache_ra_order(&ractl, ra, HPAGE_PMD_ORDER); + return fpin; + } +#endif + + /* If we don't want any read-ahead, don't bother */ + if (vm_flags & VM_RAND_READ) + return fpin; + if (!ra->ra_pages) + return fpin; + + if (vm_flags & VM_SEQ_READ) { + fpin = maybe_unlock_mmap_for_io(vmf, fpin); + page_cache_sync_ra(&ractl, ra->ra_pages); + return fpin; + } + + /* Avoid banging the cache line if not needed */ + mmap_miss = READ_ONCE(ra->mmap_miss); + if (mmap_miss < MMAP_LOTSAMISS * 10) + WRITE_ONCE(ra->mmap_miss, ++mmap_miss); + + /* + * Do we miss much more than hit in this file? If so, + * stop bothering with read-ahead. It will only hurt. + */ + if (mmap_miss > MMAP_LOTSAMISS) + return fpin; + + /* + * mmap read-around + */ + fpin = maybe_unlock_mmap_for_io(vmf, fpin); + ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2); + ra->size = ra->ra_pages; + ra->async_size = ra->ra_pages / 4; + ractl._index = ra->start; + page_cache_ra_order(&ractl, ra, 0); + return fpin; +} + +/* + * Asynchronous readahead happens when we find the page and PG_readahead, + * so we want to possibly extend the readahead further. We return the file that + * was pinned if we have to drop the mmap_lock in order to do IO. + */ +static struct file *do_async_mmap_readahead(struct vm_fault *vmf, + struct folio *folio) +{ + struct file *file = vmf->vma->vm_file; + struct file_ra_state *ra = &file->f_ra; + DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff); + struct file *fpin = NULL; + unsigned int mmap_miss; + + /* If we don't want any read-ahead, don't bother */ + if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages) + return fpin; + + mmap_miss = READ_ONCE(ra->mmap_miss); + if (mmap_miss) + WRITE_ONCE(ra->mmap_miss, --mmap_miss); + + if (folio_test_readahead(folio)) { + fpin = maybe_unlock_mmap_for_io(vmf, fpin); + page_cache_async_ra(&ractl, folio, ra->ra_pages); + } + return fpin; +} + +/** + * filemap_fault - read in file data for page fault handling + * @vmf: struct vm_fault containing details of the fault + * + * filemap_fault() is invoked via the vma operations vector for a + * mapped memory region to read in file data during a page fault. + * + * The goto's are kind of ugly, but this streamlines the normal case of having + * it in the page cache, and handles the special cases reasonably without + * having a lot of duplicated code. + * + * vma->vm_mm->mmap_lock must be held on entry. + * + * If our return value has VM_FAULT_RETRY set, it's because the mmap_lock + * may be dropped before doing I/O or by lock_folio_maybe_drop_mmap(). + * + * If our return value does not have VM_FAULT_RETRY set, the mmap_lock + * has not been released. + * + * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set. + * + * Return: bitwise-OR of %VM_FAULT_ codes. + */ +vm_fault_t filemap_fault(struct vm_fault *vmf) +{ + int error; + struct file *file = vmf->vma->vm_file; + struct file *fpin = NULL; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + pgoff_t max_idx, index = vmf->pgoff; + struct folio *folio; + vm_fault_t ret = 0; + bool mapping_locked = false; + + max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(index >= max_idx)) + return VM_FAULT_SIGBUS; + + /* + * Do we have something in the page cache already? + */ + folio = filemap_get_folio(mapping, index); + if (likely(!IS_ERR(folio))) { + /* + * We found the page, so try async readahead before waiting for + * the lock. + */ + if (!(vmf->flags & FAULT_FLAG_TRIED)) + fpin = do_async_mmap_readahead(vmf, folio); + if (unlikely(!folio_test_uptodate(folio))) { + filemap_invalidate_lock_shared(mapping); + mapping_locked = true; + } + } else { + /* No page in the page cache at all */ + count_vm_event(PGMAJFAULT); + count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); + ret = VM_FAULT_MAJOR; + fpin = do_sync_mmap_readahead(vmf); +retry_find: + /* + * See comment in filemap_create_folio() why we need + * invalidate_lock + */ + if (!mapping_locked) { + filemap_invalidate_lock_shared(mapping); + mapping_locked = true; + } + folio = __filemap_get_folio(mapping, index, + FGP_CREAT|FGP_FOR_MMAP, + vmf->gfp_mask); + if (IS_ERR(folio)) { + if (fpin) + goto out_retry; + filemap_invalidate_unlock_shared(mapping); + return VM_FAULT_OOM; + } + } + + if (!lock_folio_maybe_drop_mmap(vmf, folio, &fpin)) + goto out_retry; + + /* Did it get truncated? */ + if (unlikely(folio->mapping != mapping)) { + folio_unlock(folio); + folio_put(folio); + goto retry_find; + } + VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio); + + /* + * We have a locked page in the page cache, now we need to check + * that it's up-to-date. If not, it is going to be due to an error. + */ + if (unlikely(!folio_test_uptodate(folio))) { + /* + * The page was in cache and uptodate and now it is not. + * Strange but possible since we didn't hold the page lock all + * the time. Let's drop everything get the invalidate lock and + * try again. + */ + if (!mapping_locked) { + folio_unlock(folio); + folio_put(folio); + goto retry_find; + } + goto page_not_uptodate; + } + + /* + * We've made it this far and we had to drop our mmap_lock, now is the + * time to return to the upper layer and have it re-find the vma and + * redo the fault. + */ + if (fpin) { + folio_unlock(folio); + goto out_retry; + } + if (mapping_locked) + filemap_invalidate_unlock_shared(mapping); + + /* + * Found the page and have a reference on it. + * We must recheck i_size under page lock. + */ + max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(index >= max_idx)) { + folio_unlock(folio); + folio_put(folio); + return VM_FAULT_SIGBUS; + } + + vmf->page = folio_file_page(folio, index); + return ret | VM_FAULT_LOCKED; + +page_not_uptodate: + /* + * Umm, take care of errors if the page isn't up-to-date. + * Try to re-read it _once_. We do this synchronously, + * because there really aren't any performance issues here + * and we need to check for errors. + */ + fpin = maybe_unlock_mmap_for_io(vmf, fpin); + error = filemap_read_folio(file, mapping->a_ops->read_folio, folio); + if (fpin) + goto out_retry; + folio_put(folio); + + if (!error || error == AOP_TRUNCATED_PAGE) + goto retry_find; + filemap_invalidate_unlock_shared(mapping); + + return VM_FAULT_SIGBUS; + +out_retry: + /* + * We dropped the mmap_lock, we need to return to the fault handler to + * re-find the vma and come back and find our hopefully still populated + * page. + */ + if (!IS_ERR(folio)) + folio_put(folio); + if (mapping_locked) + filemap_invalidate_unlock_shared(mapping); + if (fpin) + fput(fpin); + return ret | VM_FAULT_RETRY; +} +EXPORT_SYMBOL(filemap_fault); + +static bool filemap_map_pmd(struct vm_fault *vmf, struct folio *folio, + pgoff_t start) +{ + struct mm_struct *mm = vmf->vma->vm_mm; + + /* Huge page is mapped? No need to proceed. */ + if (pmd_trans_huge(*vmf->pmd)) { + folio_unlock(folio); + folio_put(folio); + return true; + } + + if (pmd_none(*vmf->pmd) && folio_test_pmd_mappable(folio)) { + struct page *page = folio_file_page(folio, start); + vm_fault_t ret = do_set_pmd(vmf, page); + if (!ret) { + /* The page is mapped successfully, reference consumed. */ + folio_unlock(folio); + return true; + } + } + + if (pmd_none(*vmf->pmd) && vmf->prealloc_pte) + pmd_install(mm, vmf->pmd, &vmf->prealloc_pte); + + return false; +} + +static struct folio *next_uptodate_folio(struct xa_state *xas, + struct address_space *mapping, pgoff_t end_pgoff) +{ + struct folio *folio = xas_next_entry(xas, end_pgoff); + unsigned long max_idx; + + do { + if (!folio) + return NULL; + if (xas_retry(xas, folio)) + continue; + if (xa_is_value(folio)) + continue; + if (folio_test_locked(folio)) + continue; + if (!folio_try_get_rcu(folio)) + continue; + /* Has the page moved or been split? */ + if (unlikely(folio != xas_reload(xas))) + goto skip; + if (!folio_test_uptodate(folio) || folio_test_readahead(folio)) + goto skip; + if (!folio_trylock(folio)) + goto skip; + if (folio->mapping != mapping) + goto unlock; + if (!folio_test_uptodate(folio)) + goto unlock; + max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); + if (xas->xa_index >= max_idx) + goto unlock; + return folio; +unlock: + folio_unlock(folio); +skip: + folio_put(folio); + } while ((folio = xas_next_entry(xas, end_pgoff)) != NULL); + + return NULL; +} + +/* + * Map page range [start_page, start_page + nr_pages) of folio. + * start_page is gotten from start by folio_page(folio, start) + */ +static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, + struct folio *folio, unsigned long start, + unsigned long addr, unsigned int nr_pages, + unsigned int *mmap_miss) +{ + vm_fault_t ret = 0; + struct page *page = folio_page(folio, start); + unsigned int count = 0; + pte_t *old_ptep = vmf->pte; + + do { + if (PageHWPoison(page + count)) + goto skip; + + (*mmap_miss)++; + + /* + * NOTE: If there're PTE markers, we'll leave them to be + * handled in the specific fault path, and it'll prohibit the + * fault-around logic. + */ + if (!pte_none(vmf->pte[count])) + goto skip; + + count++; + continue; +skip: + if (count) { + set_pte_range(vmf, folio, page, count, addr); + folio_ref_add(folio, count); + if (in_range(vmf->address, addr, count * PAGE_SIZE)) + ret = VM_FAULT_NOPAGE; + } + + count++; + page += count; + vmf->pte += count; + addr += count * PAGE_SIZE; + count = 0; + } while (--nr_pages > 0); + + if (count) { + set_pte_range(vmf, folio, page, count, addr); + folio_ref_add(folio, count); + if (in_range(vmf->address, addr, count * PAGE_SIZE)) + ret = VM_FAULT_NOPAGE; + } + + vmf->pte = old_ptep; + + return ret; +} + +static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf, + struct folio *folio, unsigned long addr, + unsigned int *mmap_miss) +{ + vm_fault_t ret = 0; + struct page *page = &folio->page; + + if (PageHWPoison(page)) + return ret; + + (*mmap_miss)++; + + /* + * NOTE: If there're PTE markers, we'll leave them to be + * handled in the specific fault path, and it'll prohibit + * the fault-around logic. + */ + if (!pte_none(ptep_get(vmf->pte))) + return ret; + + if (vmf->address == addr) + ret = VM_FAULT_NOPAGE; + + set_pte_range(vmf, folio, page, 1, addr); + folio_ref_inc(folio); + + return ret; +} + +vm_fault_t filemap_map_pages(struct vm_fault *vmf, + pgoff_t start_pgoff, pgoff_t end_pgoff) +{ + struct vm_area_struct *vma = vmf->vma; + struct file *file = vma->vm_file; + struct address_space *mapping = file->f_mapping; + pgoff_t last_pgoff = start_pgoff; + unsigned long addr; + XA_STATE(xas, &mapping->i_pages, start_pgoff); + struct folio *folio; + vm_fault_t ret = 0; + unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved; + + rcu_read_lock(); + folio = next_uptodate_folio(&xas, mapping, end_pgoff); + if (!folio) + goto out; + + if (filemap_map_pmd(vmf, folio, start_pgoff)) { + ret = VM_FAULT_NOPAGE; + goto out; + } + + addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT); + vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl); + if (!vmf->pte) { + folio_unlock(folio); + folio_put(folio); + goto out; + } + do { + unsigned long end; + + addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT; + vmf->pte += xas.xa_index - last_pgoff; + last_pgoff = xas.xa_index; + end = folio->index + folio_nr_pages(folio) - 1; + nr_pages = min(end, end_pgoff) - xas.xa_index + 1; + + if (!folio_test_large(folio)) + ret |= filemap_map_order0_folio(vmf, + folio, addr, &mmap_miss); + else + ret |= filemap_map_folio_range(vmf, folio, + xas.xa_index - folio->index, addr, + nr_pages, &mmap_miss); + + folio_unlock(folio); + folio_put(folio); + } while ((folio = next_uptodate_folio(&xas, mapping, end_pgoff)) != NULL); + pte_unmap_unlock(vmf->pte, vmf->ptl); +out: + rcu_read_unlock(); + + mmap_miss_saved = READ_ONCE(file->f_ra.mmap_miss); + if (mmap_miss >= mmap_miss_saved) + WRITE_ONCE(file->f_ra.mmap_miss, 0); + else + WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss_saved - mmap_miss); + + return ret; +} +EXPORT_SYMBOL(filemap_map_pages); + +vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf) +{ + struct address_space *mapping = vmf->vma->vm_file->f_mapping; + struct folio *folio = page_folio(vmf->page); + vm_fault_t ret = VM_FAULT_LOCKED; + + sb_start_pagefault(mapping->host->i_sb); + file_update_time(vmf->vma->vm_file); + folio_lock(folio); + if (folio->mapping != mapping) { + folio_unlock(folio); + ret = VM_FAULT_NOPAGE; + goto out; + } + /* + * We mark the folio dirty already here so that when freeze is in + * progress, we are guaranteed that writeback during freezing will + * see the dirty folio and writeprotect it again. + */ + folio_mark_dirty(folio); + folio_wait_stable(folio); +out: + sb_end_pagefault(mapping->host->i_sb); + return ret; +} + +const struct vm_operations_struct generic_file_vm_ops = { + .fault = filemap_fault, + .map_pages = filemap_map_pages, + .page_mkwrite = filemap_page_mkwrite, +}; + +/* This is used for a general mmap of a disk file */ + +int generic_file_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct address_space *mapping = file->f_mapping; + + if (!mapping->a_ops->read_folio) + return -ENOEXEC; + file_accessed(file); + vma->vm_ops = &generic_file_vm_ops; + return 0; +} + +/* + * This is for filesystems which do not implement ->writepage. + */ +int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) +{ + if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) + return -EINVAL; + return generic_file_mmap(file, vma); +} +#else +vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf) +{ + return VM_FAULT_SIGBUS; +} +int generic_file_mmap(struct file *file, struct vm_area_struct *vma) +{ + return -ENOSYS; +} +int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) +{ + return -ENOSYS; +} +#endif /* CONFIG_MMU */ + +EXPORT_SYMBOL(filemap_page_mkwrite); +EXPORT_SYMBOL(generic_file_mmap); +EXPORT_SYMBOL(generic_file_readonly_mmap); + +static struct folio *do_read_cache_folio(struct address_space *mapping, + pgoff_t index, filler_t filler, struct file *file, gfp_t gfp) +{ + struct folio *folio; + int err; + + if (!filler) + filler = mapping->a_ops->read_folio; +repeat: + folio = filemap_get_folio(mapping, index); + if (IS_ERR(folio)) { + folio = filemap_alloc_folio(gfp, 0); + if (!folio) + return ERR_PTR(-ENOMEM); + err = filemap_add_folio(mapping, folio, index, gfp); + if (unlikely(err)) { + folio_put(folio); + if (err == -EEXIST) + goto repeat; + /* Presumably ENOMEM for xarray node */ + return ERR_PTR(err); + } + + goto filler; + } + if (folio_test_uptodate(folio)) + goto out; + + if (!folio_trylock(folio)) { + folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE); + goto repeat; + } + + /* Folio was truncated from mapping */ + if (!folio->mapping) { + folio_unlock(folio); + folio_put(folio); + goto repeat; + } + + /* Someone else locked and filled the page in a very small window */ + if (folio_test_uptodate(folio)) { + folio_unlock(folio); + goto out; + } + +filler: + err = filemap_read_folio(file, filler, folio); + if (err) { + folio_put(folio); + if (err == AOP_TRUNCATED_PAGE) + goto repeat; + return ERR_PTR(err); + } + +out: + folio_mark_accessed(folio); + return folio; +} + +/** + * read_cache_folio - Read into page cache, fill it if needed. + * @mapping: The address_space to read from. + * @index: The index to read. + * @filler: Function to perform the read, or NULL to use aops->read_folio(). + * @file: Passed to filler function, may be NULL if not required. + * + * Read one page into the page cache. If it succeeds, the folio returned + * will contain @index, but it may not be the first page of the folio. + * + * If the filler function returns an error, it will be returned to the + * caller. + * + * Context: May sleep. Expects mapping->invalidate_lock to be held. + * Return: An uptodate folio on success, ERR_PTR() on failure. + */ +struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index, + filler_t filler, struct file *file) +{ + return do_read_cache_folio(mapping, index, filler, file, + mapping_gfp_mask(mapping)); +} +EXPORT_SYMBOL(read_cache_folio); + +/** + * mapping_read_folio_gfp - Read into page cache, using specified allocation flags. + * @mapping: The address_space for the folio. + * @index: The index that the allocated folio will contain. + * @gfp: The page allocator flags to use if allocating. + * + * This is the same as "read_cache_folio(mapping, index, NULL, NULL)", but with + * any new memory allocations done using the specified allocation flags. + * + * The most likely error from this function is EIO, but ENOMEM is + * possible and so is EINTR. If ->read_folio returns another error, + * that will be returned to the caller. + * + * The function expects mapping->invalidate_lock to be already held. + * + * Return: Uptodate folio on success, ERR_PTR() on failure. + */ +struct folio *mapping_read_folio_gfp(struct address_space *mapping, + pgoff_t index, gfp_t gfp) +{ + return do_read_cache_folio(mapping, index, NULL, NULL, gfp); +} +EXPORT_SYMBOL(mapping_read_folio_gfp); + +static struct page *do_read_cache_page(struct address_space *mapping, + pgoff_t index, filler_t *filler, struct file *file, gfp_t gfp) +{ + struct folio *folio; + + folio = do_read_cache_folio(mapping, index, filler, file, gfp); + if (IS_ERR(folio)) + return &folio->page; + return folio_file_page(folio, index); +} + +struct page *read_cache_page(struct address_space *mapping, + pgoff_t index, filler_t *filler, struct file *file) +{ + return do_read_cache_page(mapping, index, filler, file, + mapping_gfp_mask(mapping)); +} +EXPORT_SYMBOL(read_cache_page); + +/** + * read_cache_page_gfp - read into page cache, using specified page allocation flags. + * @mapping: the page's address_space + * @index: the page index + * @gfp: the page allocator flags to use if allocating + * + * This is the same as "read_mapping_page(mapping, index, NULL)", but with + * any new page allocations done using the specified allocation flags. + * + * If the page does not get brought uptodate, return -EIO. + * + * The function expects mapping->invalidate_lock to be already held. + * + * Return: up to date page on success, ERR_PTR() on failure. + */ +struct page *read_cache_page_gfp(struct address_space *mapping, + pgoff_t index, + gfp_t gfp) +{ + return do_read_cache_page(mapping, index, NULL, NULL, gfp); +} +EXPORT_SYMBOL(read_cache_page_gfp); + +/* + * Warn about a page cache invalidation failure during a direct I/O write. + */ +static void dio_warn_stale_pagecache(struct file *filp) +{ + static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); + char pathname[128]; + char *path; + + errseq_set(&filp->f_mapping->wb_err, -EIO); + if (__ratelimit(&_rs)) { + path = file_path(filp, pathname, sizeof(pathname)); + if (IS_ERR(path)) + path = "(unknown)"; + pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n"); + pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid, + current->comm); + } +} + +void kiocb_invalidate_post_direct_write(struct kiocb *iocb, size_t count) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + + if (mapping->nrpages && + invalidate_inode_pages2_range(mapping, + iocb->ki_pos >> PAGE_SHIFT, + (iocb->ki_pos + count - 1) >> PAGE_SHIFT)) + dio_warn_stale_pagecache(iocb->ki_filp); +} + +ssize_t +generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + size_t write_len = iov_iter_count(from); + ssize_t written; + + /* + * If a page can not be invalidated, return 0 to fall back + * to buffered write. + */ + written = kiocb_invalidate_pages(iocb, write_len); + if (written) { + if (written == -EBUSY) + return 0; + return written; + } + + written = mapping->a_ops->direct_IO(iocb, from); + + /* + * Finally, try again to invalidate clean pages which might have been + * cached by non-direct readahead, or faulted in by get_user_pages() + * if the source of the write was an mmap'ed region of the file + * we're writing. Either one is a pretty crazy thing to do, + * so we don't support it 100%. If this invalidation + * fails, tough, the write still worked... + * + * Most of the time we do not need this since dio_complete() will do + * the invalidation for us. However there are some file systems that + * do not end up with dio_complete() being called, so let's not break + * them by removing it completely. + * + * Noticeable example is a blkdev_direct_IO(). + * + * Skip invalidation for async writes or if mapping has no pages. + */ + if (written > 0) { + struct inode *inode = mapping->host; + loff_t pos = iocb->ki_pos; + + kiocb_invalidate_post_direct_write(iocb, written); + pos += written; + write_len -= written; + if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { + i_size_write(inode, pos); + mark_inode_dirty(inode); + } + iocb->ki_pos = pos; + } + if (written != -EIOCBQUEUED) + iov_iter_revert(from, write_len - iov_iter_count(from)); + return written; +} +EXPORT_SYMBOL(generic_file_direct_write); + +ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) +{ + struct file *file = iocb->ki_filp; + loff_t pos = iocb->ki_pos; + struct address_space *mapping = file->f_mapping; + const struct address_space_operations *a_ops = mapping->a_ops; + long status = 0; + ssize_t written = 0; + + do { + struct page *page; + unsigned long offset; /* Offset into pagecache page */ + unsigned long bytes; /* Bytes to write to page */ + size_t copied; /* Bytes copied from user */ + void *fsdata = NULL; + + offset = (pos & (PAGE_SIZE - 1)); + bytes = min_t(unsigned long, PAGE_SIZE - offset, + iov_iter_count(i)); + +again: + /* + * Bring in the user page that we will copy from _first_. + * Otherwise there's a nasty deadlock on copying from the + * same page as we're writing to, without it being marked + * up-to-date. + */ + if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) { + status = -EFAULT; + break; + } + + if (fatal_signal_pending(current)) { + status = -EINTR; + break; + } + + status = a_ops->write_begin(file, mapping, pos, bytes, + &page, &fsdata); + if (unlikely(status < 0)) + break; + + if (mapping_writably_mapped(mapping)) + flush_dcache_page(page); + + copied = copy_page_from_iter_atomic(page, offset, bytes, i); + flush_dcache_page(page); + + status = a_ops->write_end(file, mapping, pos, bytes, copied, + page, fsdata); + if (unlikely(status != copied)) { + iov_iter_revert(i, copied - max(status, 0L)); + if (unlikely(status < 0)) + break; + } + cond_resched(); + + if (unlikely(status == 0)) { + /* + * A short copy made ->write_end() reject the + * thing entirely. Might be memory poisoning + * halfway through, might be a race with munmap, + * might be severe memory pressure. + */ + if (copied) + bytes = copied; + goto again; + } + pos += status; + written += status; + + balance_dirty_pages_ratelimited(mapping); + } while (iov_iter_count(i)); + + if (!written) + return status; + iocb->ki_pos += written; + return written; +} +EXPORT_SYMBOL(generic_perform_write); + +/** + * __generic_file_write_iter - write data to a file + * @iocb: IO state structure (file, offset, etc.) + * @from: iov_iter with data to write + * + * This function does all the work needed for actually writing data to a + * file. It does all basic checks, removes SUID from the file, updates + * modification times and calls proper subroutines depending on whether we + * do direct IO or a standard buffered write. + * + * It expects i_rwsem to be grabbed unless we work on a block device or similar + * object which does not need locking at all. + * + * This function does *not* take care of syncing data in case of O_SYNC write. + * A caller has to handle it. This is mainly due to the fact that we want to + * avoid syncing under i_rwsem. + * + * Return: + * * number of bytes written, even for truncated writes + * * negative error code if no data has been written at all + */ +ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + ssize_t ret; + + ret = file_remove_privs(file); + if (ret) + return ret; + + ret = file_update_time(file); + if (ret) + return ret; + + if (iocb->ki_flags & IOCB_DIRECT) { + ret = generic_file_direct_write(iocb, from); + /* + * If the write stopped short of completing, fall back to + * buffered writes. Some filesystems do this for writes to + * holes, for example. For DAX files, a buffered write will + * not succeed (even if it did, DAX does not handle dirty + * page-cache pages correctly). + */ + if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) + return ret; + return direct_write_fallback(iocb, from, ret, + generic_perform_write(iocb, from)); + } + + return generic_perform_write(iocb, from); +} +EXPORT_SYMBOL(__generic_file_write_iter); + +/** + * generic_file_write_iter - write data to a file + * @iocb: IO state structure + * @from: iov_iter with data to write + * + * This is a wrapper around __generic_file_write_iter() to be used by most + * filesystems. It takes care of syncing the file in case of O_SYNC file + * and acquires i_rwsem as needed. + * Return: + * * negative error code if no data has been written at all of + * vfs_fsync_range() failed for a synchronous write + * * number of bytes written, even for truncated writes + */ +ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + struct file *file = iocb->ki_filp; + struct inode *inode = file->f_mapping->host; + ssize_t ret; + + inode_lock(inode); + ret = generic_write_checks(iocb, from); + if (ret > 0) + ret = __generic_file_write_iter(iocb, from); + inode_unlock(inode); + + if (ret > 0) + ret = generic_write_sync(iocb, ret); + return ret; +} +EXPORT_SYMBOL(generic_file_write_iter); + +/** + * filemap_release_folio() - Release fs-specific metadata on a folio. + * @folio: The folio which the kernel is trying to free. + * @gfp: Memory allocation flags (and I/O mode). + * + * The address_space is trying to release any data attached to a folio + * (presumably at folio->private). + * + * This will also be called if the private_2 flag is set on a page, + * indicating that the folio has other metadata associated with it. + * + * The @gfp argument specifies whether I/O may be performed to release + * this page (__GFP_IO), and whether the call may block + * (__GFP_RECLAIM & __GFP_FS). + * + * Return: %true if the release was successful, otherwise %false. + */ +bool filemap_release_folio(struct folio *folio, gfp_t gfp) +{ + struct address_space * const mapping = folio->mapping; + + BUG_ON(!folio_test_locked(folio)); + if (!folio_needs_release(folio)) + return true; + if (folio_test_writeback(folio)) + return false; + + if (mapping && mapping->a_ops->release_folio) + return mapping->a_ops->release_folio(folio, gfp); + return try_to_free_buffers(folio); +} +EXPORT_SYMBOL(filemap_release_folio); + +#ifdef CONFIG_CACHESTAT_SYSCALL +/** + * filemap_cachestat() - compute the page cache statistics of a mapping + * @mapping: The mapping to compute the statistics for. + * @first_index: The starting page cache index. + * @last_index: The final page index (inclusive). + * @cs: the cachestat struct to write the result to. + * + * This will query the page cache statistics of a mapping in the + * page range of [first_index, last_index] (inclusive). The statistics + * queried include: number of dirty pages, number of pages marked for + * writeback, and the number of (recently) evicted pages. + */ +static void filemap_cachestat(struct address_space *mapping, + pgoff_t first_index, pgoff_t last_index, struct cachestat *cs) +{ + XA_STATE(xas, &mapping->i_pages, first_index); + struct folio *folio; + + rcu_read_lock(); + xas_for_each(&xas, folio, last_index) { + unsigned long nr_pages; + pgoff_t folio_first_index, folio_last_index; + + if (xas_retry(&xas, folio)) + continue; + + if (xa_is_value(folio)) { + /* page is evicted */ + void *shadow = (void *)folio; + bool workingset; /* not used */ + int order = xa_get_order(xas.xa, xas.xa_index); + + nr_pages = 1 << order; + folio_first_index = round_down(xas.xa_index, 1 << order); + folio_last_index = folio_first_index + nr_pages - 1; + + /* Folios might straddle the range boundaries, only count covered pages */ + if (folio_first_index < first_index) + nr_pages -= first_index - folio_first_index; + + if (folio_last_index > last_index) + nr_pages -= folio_last_index - last_index; + + cs->nr_evicted += nr_pages; + +#ifdef CONFIG_SWAP /* implies CONFIG_MMU */ + if (shmem_mapping(mapping)) { + /* shmem file - in swap cache */ + swp_entry_t swp = radix_to_swp_entry(folio); + + shadow = get_shadow_from_swap_cache(swp); + } +#endif + if (workingset_test_recent(shadow, true, &workingset)) + cs->nr_recently_evicted += nr_pages; + + goto resched; + } + + nr_pages = folio_nr_pages(folio); + folio_first_index = folio_pgoff(folio); + folio_last_index = folio_first_index + nr_pages - 1; + + /* Folios might straddle the range boundaries, only count covered pages */ + if (folio_first_index < first_index) + nr_pages -= first_index - folio_first_index; + + if (folio_last_index > last_index) + nr_pages -= folio_last_index - last_index; + + /* page is in cache */ + cs->nr_cache += nr_pages; + + if (folio_test_dirty(folio)) + cs->nr_dirty += nr_pages; + + if (folio_test_writeback(folio)) + cs->nr_writeback += nr_pages; + +resched: + if (need_resched()) { + xas_pause(&xas); + cond_resched_rcu(); + } + } + rcu_read_unlock(); +} + +/* + * The cachestat(2) system call. + * + * cachestat() returns the page cache statistics of a file in the + * bytes range specified by `off` and `len`: number of cached pages, + * number of dirty pages, number of pages marked for writeback, + * number of evicted pages, and number of recently evicted pages. + * + * An evicted page is a page that is previously in the page cache + * but has been evicted since. A page is recently evicted if its last + * eviction was recent enough that its reentry to the cache would + * indicate that it is actively being used by the system, and that + * there is memory pressure on the system. + * + * `off` and `len` must be non-negative integers. If `len` > 0, + * the queried range is [`off`, `off` + `len`]. If `len` == 0, + * we will query in the range from `off` to the end of the file. + * + * The `flags` argument is unused for now, but is included for future + * extensibility. User should pass 0 (i.e no flag specified). + * + * Currently, hugetlbfs is not supported. + * + * Because the status of a page can change after cachestat() checks it + * but before it returns to the application, the returned values may + * contain stale information. + * + * return values: + * zero - success + * -EFAULT - cstat or cstat_range points to an illegal address + * -EINVAL - invalid flags + * -EBADF - invalid file descriptor + * -EOPNOTSUPP - file descriptor is of a hugetlbfs file + */ +SYSCALL_DEFINE4(cachestat, unsigned int, fd, + struct cachestat_range __user *, cstat_range, + struct cachestat __user *, cstat, unsigned int, flags) +{ + struct fd f = fdget(fd); + struct address_space *mapping; + struct cachestat_range csr; + struct cachestat cs; + pgoff_t first_index, last_index; + + if (!f.file) + return -EBADF; + + if (copy_from_user(&csr, cstat_range, + sizeof(struct cachestat_range))) { + fdput(f); + return -EFAULT; + } + + /* hugetlbfs is not supported */ + if (is_file_hugepages(f.file)) { + fdput(f); + return -EOPNOTSUPP; + } + + if (flags != 0) { + fdput(f); + return -EINVAL; + } + + first_index = csr.off >> PAGE_SHIFT; + last_index = + csr.len == 0 ? ULONG_MAX : (csr.off + csr.len - 1) >> PAGE_SHIFT; + memset(&cs, 0, sizeof(struct cachestat)); + mapping = f.file->f_mapping; + filemap_cachestat(mapping, first_index, last_index, &cs); + fdput(f); + + if (copy_to_user(cstat, &cs, sizeof(struct cachestat))) + return -EFAULT; + + return 0; +} +#endif /* CONFIG_CACHESTAT_SYSCALL */ |