| /* |
| * fs/dax.c - Direct Access filesystem code |
| * Copyright (c) 2013-2014 Intel Corporation |
| * Author: Matthew Wilcox <matthew.r.wilcox@intel.com> |
| * Author: Ross Zwisler <ross.zwisler@linux.intel.com> |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms and conditions of the GNU General Public License, |
| * version 2, as published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| * more details. |
| */ |
| |
| #include <linux/atomic.h> |
| #include <linux/blkdev.h> |
| #include <linux/buffer_head.h> |
| #include <linux/dax.h> |
| #include <linux/fs.h> |
| #include <linux/genhd.h> |
| #include <linux/highmem.h> |
| #include <linux/memcontrol.h> |
| #include <linux/mm.h> |
| #include <linux/mutex.h> |
| #include <linux/pagevec.h> |
| #include <linux/sched.h> |
| #include <linux/sched/signal.h> |
| #include <linux/uio.h> |
| #include <linux/vmstat.h> |
| #include <linux/pfn_t.h> |
| #include <linux/sizes.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/iomap.h> |
| #include "internal.h" |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/fs_dax.h> |
| |
| /* We choose 4096 entries - same as per-zone page wait tables */ |
| #define DAX_WAIT_TABLE_BITS 12 |
| #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) |
| |
| /* The 'colour' (ie low bits) within a PMD of a page offset. */ |
| #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) |
| #define PG_PMD_NR (PMD_SIZE >> PAGE_SHIFT) |
| |
| static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; |
| |
| static int __init init_dax_wait_table(void) |
| { |
| int i; |
| |
| for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++) |
| init_waitqueue_head(wait_table + i); |
| return 0; |
| } |
| fs_initcall(init_dax_wait_table); |
| |
| /* |
| * We use lowest available bit in exceptional entry for locking, one bit for |
| * the entry size (PMD) and two more to tell us if the entry is a zero page or |
| * an empty entry that is just used for locking. In total four special bits. |
| * |
| * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE |
| * and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem |
| * block allocation. |
| */ |
| #define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4) |
| #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) |
| #define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) |
| #define RADIX_DAX_ZERO_PAGE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) |
| #define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3)) |
| |
| static unsigned long dax_radix_pfn(void *entry) |
| { |
| return (unsigned long)entry >> RADIX_DAX_SHIFT; |
| } |
| |
| static void *dax_radix_locked_entry(unsigned long pfn, unsigned long flags) |
| { |
| return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags | |
| (pfn << RADIX_DAX_SHIFT) | RADIX_DAX_ENTRY_LOCK); |
| } |
| |
| static unsigned int dax_radix_order(void *entry) |
| { |
| if ((unsigned long)entry & RADIX_DAX_PMD) |
| return PMD_SHIFT - PAGE_SHIFT; |
| return 0; |
| } |
| |
| static int dax_is_pmd_entry(void *entry) |
| { |
| return (unsigned long)entry & RADIX_DAX_PMD; |
| } |
| |
| static int dax_is_pte_entry(void *entry) |
| { |
| return !((unsigned long)entry & RADIX_DAX_PMD); |
| } |
| |
| static int dax_is_zero_entry(void *entry) |
| { |
| return (unsigned long)entry & RADIX_DAX_ZERO_PAGE; |
| } |
| |
| static int dax_is_empty_entry(void *entry) |
| { |
| return (unsigned long)entry & RADIX_DAX_EMPTY; |
| } |
| |
| /* |
| * DAX radix tree locking |
| */ |
| struct exceptional_entry_key { |
| struct address_space *mapping; |
| pgoff_t entry_start; |
| }; |
| |
| struct wait_exceptional_entry_queue { |
| wait_queue_entry_t wait; |
| struct exceptional_entry_key key; |
| }; |
| |
| static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping, |
| pgoff_t index, void *entry, struct exceptional_entry_key *key) |
| { |
| unsigned long hash; |
| |
| /* |
| * If 'entry' is a PMD, align the 'index' that we use for the wait |
| * queue to the start of that PMD. This ensures that all offsets in |
| * the range covered by the PMD map to the same bit lock. |
| */ |
| if (dax_is_pmd_entry(entry)) |
| index &= ~PG_PMD_COLOUR; |
| |
| key->mapping = mapping; |
| key->entry_start = index; |
| |
| hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS); |
| return wait_table + hash; |
| } |
| |
| static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mode, |
| int sync, void *keyp) |
| { |
| struct exceptional_entry_key *key = keyp; |
| struct wait_exceptional_entry_queue *ewait = |
| container_of(wait, struct wait_exceptional_entry_queue, wait); |
| |
| if (key->mapping != ewait->key.mapping || |
| key->entry_start != ewait->key.entry_start) |
| return 0; |
| return autoremove_wake_function(wait, mode, sync, NULL); |
| } |
| |
| /* |
| * @entry may no longer be the entry at the index in the mapping. |
| * The important information it's conveying is whether the entry at |
| * this index used to be a PMD entry. |
| */ |
| static void dax_wake_mapping_entry_waiter(struct address_space *mapping, |
| pgoff_t index, void *entry, bool wake_all) |
| { |
| struct exceptional_entry_key key; |
| wait_queue_head_t *wq; |
| |
| wq = dax_entry_waitqueue(mapping, index, entry, &key); |
| |
| /* |
| * Checking for locked entry and prepare_to_wait_exclusive() happens |
| * under the i_pages lock, ditto for entry handling in our callers. |
| * So at this point all tasks that could have seen our entry locked |
| * must be in the waitqueue and the following check will see them. |
| */ |
| if (waitqueue_active(wq)) |
| __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key); |
| } |
| |
| /* |
| * Check whether the given slot is locked. Must be called with the i_pages |
| * lock held. |
| */ |
| static inline int slot_locked(struct address_space *mapping, void **slot) |
| { |
| unsigned long entry = (unsigned long) |
| radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); |
| return entry & RADIX_DAX_ENTRY_LOCK; |
| } |
| |
| /* |
| * Mark the given slot as locked. Must be called with the i_pages lock held. |
| */ |
| static inline void *lock_slot(struct address_space *mapping, void **slot) |
| { |
| unsigned long entry = (unsigned long) |
| radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); |
| |
| entry |= RADIX_DAX_ENTRY_LOCK; |
| radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry); |
| return (void *)entry; |
| } |
| |
| /* |
| * Mark the given slot as unlocked. Must be called with the i_pages lock held. |
| */ |
| static inline void *unlock_slot(struct address_space *mapping, void **slot) |
| { |
| unsigned long entry = (unsigned long) |
| radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock); |
| |
| entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; |
| radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry); |
| return (void *)entry; |
| } |
| |
| /* |
| * Lookup entry in radix tree, wait for it to become unlocked if it is |
| * exceptional entry and return it. The caller must call |
| * put_unlocked_mapping_entry() when he decided not to lock the entry or |
| * put_locked_mapping_entry() when he locked the entry and now wants to |
| * unlock it. |
| * |
| * Must be called with the i_pages lock held. |
| */ |
| static void *__get_unlocked_mapping_entry(struct address_space *mapping, |
| pgoff_t index, void ***slotp, bool (*wait_fn)(void)) |
| { |
| void *entry, **slot; |
| struct wait_exceptional_entry_queue ewait; |
| wait_queue_head_t *wq; |
| |
| init_wait(&ewait.wait); |
| ewait.wait.func = wake_exceptional_entry_func; |
| |
| for (;;) { |
| bool revalidate; |
| |
| entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, |
| &slot); |
| if (!entry || |
| WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) || |
| !slot_locked(mapping, slot)) { |
| if (slotp) |
| *slotp = slot; |
| return entry; |
| } |
| |
| wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key); |
| prepare_to_wait_exclusive(wq, &ewait.wait, |
| TASK_UNINTERRUPTIBLE); |
| xa_unlock_irq(&mapping->i_pages); |
| revalidate = wait_fn(); |
| finish_wait(wq, &ewait.wait); |
| xa_lock_irq(&mapping->i_pages); |
| if (revalidate) |
| return ERR_PTR(-EAGAIN); |
| } |
| } |
| |
| static bool entry_wait(void) |
| { |
| schedule(); |
| /* |
| * Never return an ERR_PTR() from |
| * __get_unlocked_mapping_entry(), just keep looping. |
| */ |
| return false; |
| } |
| |
| static void *get_unlocked_mapping_entry(struct address_space *mapping, |
| pgoff_t index, void ***slotp) |
| { |
| return __get_unlocked_mapping_entry(mapping, index, slotp, entry_wait); |
| } |
| |
| static void unlock_mapping_entry(struct address_space *mapping, pgoff_t index) |
| { |
| void *entry, **slot; |
| |
| xa_lock_irq(&mapping->i_pages); |
| entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot); |
| if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) || |
| !slot_locked(mapping, slot))) { |
| xa_unlock_irq(&mapping->i_pages); |
| return; |
| } |
| unlock_slot(mapping, slot); |
| xa_unlock_irq(&mapping->i_pages); |
| dax_wake_mapping_entry_waiter(mapping, index, entry, false); |
| } |
| |
| static void put_locked_mapping_entry(struct address_space *mapping, |
| pgoff_t index) |
| { |
| unlock_mapping_entry(mapping, index); |
| } |
| |
| /* |
| * Called when we are done with radix tree entry we looked up via |
| * get_unlocked_mapping_entry() and which we didn't lock in the end. |
| */ |
| static void put_unlocked_mapping_entry(struct address_space *mapping, |
| pgoff_t index, void *entry) |
| { |
| if (!entry) |
| return; |
| |
| /* We have to wake up next waiter for the radix tree entry lock */ |
| dax_wake_mapping_entry_waiter(mapping, index, entry, false); |
| } |
| |
| static unsigned long dax_entry_size(void *entry) |
| { |
| if (dax_is_zero_entry(entry)) |
| return 0; |
| else if (dax_is_empty_entry(entry)) |
| return 0; |
| else if (dax_is_pmd_entry(entry)) |
| return PMD_SIZE; |
| else |
| return PAGE_SIZE; |
| } |
| |
| static unsigned long dax_radix_end_pfn(void *entry) |
| { |
| return dax_radix_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE; |
| } |
| |
| /* |
| * Iterate through all mapped pfns represented by an entry, i.e. skip |
| * 'empty' and 'zero' entries. |
| */ |
| #define for_each_mapped_pfn(entry, pfn) \ |
| for (pfn = dax_radix_pfn(entry); \ |
| pfn < dax_radix_end_pfn(entry); pfn++) |
| |
| /* |
| * TODO: for reflink+dax we need a way to associate a single page with |
| * multiple address_space instances at different linear_page_index() |
| * offsets. |
| */ |
| static void dax_associate_entry(void *entry, struct address_space *mapping, |
| struct vm_area_struct *vma, unsigned long address) |
| { |
| unsigned long size = dax_entry_size(entry), pfn, index; |
| int i = 0; |
| |
| if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
| return; |
| |
| index = linear_page_index(vma, address & ~(size - 1)); |
| for_each_mapped_pfn(entry, pfn) { |
| struct page *page = pfn_to_page(pfn); |
| |
| WARN_ON_ONCE(page->mapping); |
| page->mapping = mapping; |
| page->index = index + i++; |
| } |
| } |
| |
| static void dax_disassociate_entry(void *entry, struct address_space *mapping, |
| bool trunc) |
| { |
| unsigned long pfn; |
| |
| if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
| return; |
| |
| for_each_mapped_pfn(entry, pfn) { |
| struct page *page = pfn_to_page(pfn); |
| |
| WARN_ON_ONCE(trunc && page_ref_count(page) > 1); |
| WARN_ON_ONCE(page->mapping && page->mapping != mapping); |
| page->mapping = NULL; |
| page->index = 0; |
| } |
| } |
| |
| static struct page *dax_busy_page(void *entry) |
| { |
| unsigned long pfn; |
| |
| for_each_mapped_pfn(entry, pfn) { |
| struct page *page = pfn_to_page(pfn); |
| |
| if (page_ref_count(page) > 1) |
| return page; |
| } |
| return NULL; |
| } |
| |
| static bool entry_wait_revalidate(void) |
| { |
| rcu_read_unlock(); |
| schedule(); |
| rcu_read_lock(); |
| |
| /* |
| * Tell __get_unlocked_mapping_entry() to take a break, we need |
| * to revalidate page->mapping after dropping locks |
| */ |
| return true; |
| } |
| |
| bool dax_lock_mapping_entry(struct page *page) |
| { |
| pgoff_t index; |
| struct inode *inode; |
| bool did_lock = false; |
| void *entry = NULL, **slot; |
| struct address_space *mapping; |
| |
| rcu_read_lock(); |
| for (;;) { |
| mapping = READ_ONCE(page->mapping); |
| |
| if (!dax_mapping(mapping)) |
| break; |
| |
| /* |
| * In the device-dax case there's no need to lock, a |
| * struct dev_pagemap pin is sufficient to keep the |
| * inode alive, and we assume we have dev_pagemap pin |
| * otherwise we would not have a valid pfn_to_page() |
| * translation. |
| */ |
| inode = mapping->host; |
| if (S_ISCHR(inode->i_mode)) { |
| did_lock = true; |
| break; |
| } |
| |
| xa_lock_irq(&mapping->i_pages); |
| if (mapping != page->mapping) { |
| xa_unlock_irq(&mapping->i_pages); |
| continue; |
| } |
| index = page->index; |
| |
| entry = __get_unlocked_mapping_entry(mapping, index, &slot, |
| entry_wait_revalidate); |
| if (!entry) { |
| xa_unlock_irq(&mapping->i_pages); |
| break; |
| } else if (IS_ERR(entry)) { |
| xa_unlock_irq(&mapping->i_pages); |
| WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN); |
| continue; |
| } |
| lock_slot(mapping, slot); |
| did_lock = true; |
| xa_unlock_irq(&mapping->i_pages); |
| break; |
| } |
| rcu_read_unlock(); |
| |
| return did_lock; |
| } |
| |
| void dax_unlock_mapping_entry(struct page *page) |
| { |
| struct address_space *mapping = page->mapping; |
| struct inode *inode = mapping->host; |
| |
| if (S_ISCHR(inode->i_mode)) |
| return; |
| |
| unlock_mapping_entry(mapping, page->index); |
| } |
| |
| /* |
| * Find radix tree entry at given index. If it points to an exceptional entry, |
| * return it with the radix tree entry locked. If the radix tree doesn't |
| * contain given index, create an empty exceptional entry for the index and |
| * return with it locked. |
| * |
| * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will |
| * either return that locked entry or will return an error. This error will |
| * happen if there are any 4k entries within the 2MiB range that we are |
| * requesting. |
| * |
| * We always favor 4k entries over 2MiB entries. There isn't a flow where we |
| * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB |
| * insertion will fail if it finds any 4k entries already in the tree, and a |
| * 4k insertion will cause an existing 2MiB entry to be unmapped and |
| * downgraded to 4k entries. This happens for both 2MiB huge zero pages as |
| * well as 2MiB empty entries. |
| * |
| * The exception to this downgrade path is for 2MiB DAX PMD entries that have |
| * real storage backing them. We will leave these real 2MiB DAX entries in |
| * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry. |
| * |
| * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For |
| * persistent memory the benefit is doubtful. We can add that later if we can |
| * show it helps. |
| */ |
| static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, |
| unsigned long size_flag) |
| { |
| bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */ |
| void *entry, **slot; |
| |
| restart: |
| xa_lock_irq(&mapping->i_pages); |
| entry = get_unlocked_mapping_entry(mapping, index, &slot); |
| |
| if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) { |
| entry = ERR_PTR(-EIO); |
| goto out_unlock; |
| } |
| |
| if (entry) { |
| if (size_flag & RADIX_DAX_PMD) { |
| if (dax_is_pte_entry(entry)) { |
| put_unlocked_mapping_entry(mapping, index, |
| entry); |
| entry = ERR_PTR(-EEXIST); |
| goto out_unlock; |
| } |
| } else { /* trying to grab a PTE entry */ |
| if (dax_is_pmd_entry(entry) && |
| (dax_is_zero_entry(entry) || |
| dax_is_empty_entry(entry))) { |
| pmd_downgrade = true; |
| } |
| } |
| } |
| |
| /* No entry for given index? Make sure radix tree is big enough. */ |
| if (!entry || pmd_downgrade) { |
| int err; |
| |
| if (pmd_downgrade) { |
| /* |
| * Make sure 'entry' remains valid while we drop |
| * the i_pages lock. |
| */ |
| entry = lock_slot(mapping, slot); |
| } |
| |
| xa_unlock_irq(&mapping->i_pages); |
| /* |
| * Besides huge zero pages the only other thing that gets |
| * downgraded are empty entries which don't need to be |
| * unmapped. |
| */ |
| if (pmd_downgrade && dax_is_zero_entry(entry)) |
| unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR, |
| PG_PMD_NR, false); |
| |
| err = radix_tree_preload( |
| mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); |
| if (err) { |
| if (pmd_downgrade) |
| put_locked_mapping_entry(mapping, index); |
| return ERR_PTR(err); |
| } |
| xa_lock_irq(&mapping->i_pages); |
| |
| if (!entry) { |
| /* |
| * We needed to drop the i_pages lock while calling |
| * radix_tree_preload() and we didn't have an entry to |
| * lock. See if another thread inserted an entry at |
| * our index during this time. |
| */ |
| entry = __radix_tree_lookup(&mapping->i_pages, index, |
| NULL, &slot); |
| if (entry) { |
| radix_tree_preload_end(); |
| xa_unlock_irq(&mapping->i_pages); |
| goto restart; |
| } |
| } |
| |
| if (pmd_downgrade) { |
| dax_disassociate_entry(entry, mapping, false); |
| radix_tree_delete(&mapping->i_pages, index); |
| mapping->nrexceptional--; |
| dax_wake_mapping_entry_waiter(mapping, index, entry, |
| true); |
| } |
| |
| entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY); |
| |
| err = __radix_tree_insert(&mapping->i_pages, index, |
| dax_radix_order(entry), entry); |
| radix_tree_preload_end(); |
| if (err) { |
| xa_unlock_irq(&mapping->i_pages); |
| /* |
| * Our insertion of a DAX entry failed, most likely |
| * because we were inserting a PMD entry and it |
| * collided with a PTE sized entry at a different |
| * index in the PMD range. We haven't inserted |
| * anything into the radix tree and have no waiters to |
| * wake. |
| */ |
| return ERR_PTR(err); |
| } |
| /* Good, we have inserted empty locked entry into the tree. */ |
| mapping->nrexceptional++; |
| xa_unlock_irq(&mapping->i_pages); |
| return entry; |
| } |
| entry = lock_slot(mapping, slot); |
| out_unlock: |
| xa_unlock_irq(&mapping->i_pages); |
| return entry; |
| } |
| |
| /** |
| * dax_layout_busy_page - find first pinned page in @mapping |
| * @mapping: address space to scan for a page with ref count > 1 |
| * |
| * DAX requires ZONE_DEVICE mapped pages. These pages are never |
| * 'onlined' to the page allocator so they are considered idle when |
| * page->count == 1. A filesystem uses this interface to determine if |
| * any page in the mapping is busy, i.e. for DMA, or other |
| * get_user_pages() usages. |
| * |
| * It is expected that the filesystem is holding locks to block the |
| * establishment of new mappings in this address_space. I.e. it expects |
| * to be able to run unmap_mapping_range() and subsequently not race |
| * mapping_mapped() becoming true. |
| */ |
| struct page *dax_layout_busy_page(struct address_space *mapping) |
| { |
| pgoff_t indices[PAGEVEC_SIZE]; |
| struct page *page = NULL; |
| struct pagevec pvec; |
| pgoff_t index, end; |
| unsigned i; |
| |
| /* |
| * In the 'limited' case get_user_pages() for dax is disabled. |
| */ |
| if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) |
| return NULL; |
| |
| if (!dax_mapping(mapping) || !mapping_mapped(mapping)) |
| return NULL; |
| |
| pagevec_init(&pvec); |
| index = 0; |
| end = -1; |
| |
| /* |
| * If we race get_user_pages_fast() here either we'll see the |
| * elevated page count in the pagevec_lookup and wait, or |
| * get_user_pages_fast() will see that the page it took a reference |
| * against is no longer mapped in the page tables and bail to the |
| * get_user_pages() slow path. The slow path is protected by |
| * pte_lock() and pmd_lock(). New references are not taken without |
| * holding those locks, and unmap_mapping_range() will not zero the |
| * pte or pmd without holding the respective lock, so we are |
| * guaranteed to either see new references or prevent new |
| * references from being established. |
| */ |
| unmap_mapping_range(mapping, 0, 0, 1); |
| |
| while (index < end && pagevec_lookup_entries(&pvec, mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE), |
| indices)) { |
| pgoff_t nr_pages = 1; |
| |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *pvec_ent = pvec.pages[i]; |
| void *entry; |
| |
| index = indices[i]; |
| if (index >= end) |
| break; |
| |
| if (WARN_ON_ONCE( |
| !radix_tree_exceptional_entry(pvec_ent))) |
| continue; |
| |
| xa_lock_irq(&mapping->i_pages); |
| entry = get_unlocked_mapping_entry(mapping, index, NULL); |
| if (entry) { |
| page = dax_busy_page(entry); |
| /* |
| * Account for multi-order entries at |
| * the end of the pagevec. |
| */ |
| if (i + 1 >= pagevec_count(&pvec)) |
| nr_pages = 1UL << dax_radix_order(entry); |
| } |
| put_unlocked_mapping_entry(mapping, index, entry); |
| xa_unlock_irq(&mapping->i_pages); |
| if (page) |
| break; |
| } |
| |
| /* |
| * We don't expect normal struct page entries to exist in our |
| * tree, but we keep these pagevec calls so that this code is |
| * consistent with the common pattern for handling pagevecs |
| * throughout the kernel. |
| */ |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| index += nr_pages; |
| |
| if (page) |
| break; |
| } |
| return page; |
| } |
| EXPORT_SYMBOL_GPL(dax_layout_busy_page); |
| |
| static int __dax_invalidate_mapping_entry(struct address_space *mapping, |
| pgoff_t index, bool trunc) |
| { |
| int ret = 0; |
| void *entry; |
| struct radix_tree_root *pages = &mapping->i_pages; |
| |
| xa_lock_irq(pages); |
| entry = get_unlocked_mapping_entry(mapping, index, NULL); |
| if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry))) |
| goto out; |
| if (!trunc && |
| (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) || |
| radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE))) |
| goto out; |
| dax_disassociate_entry(entry, mapping, trunc); |
| radix_tree_delete(pages, index); |
| mapping->nrexceptional--; |
| ret = 1; |
| out: |
| put_unlocked_mapping_entry(mapping, index, entry); |
| xa_unlock_irq(pages); |
| return ret; |
| } |
| /* |
| * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree |
| * entry to get unlocked before deleting it. |
| */ |
| int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) |
| { |
| int ret = __dax_invalidate_mapping_entry(mapping, index, true); |
| |
| /* |
| * This gets called from truncate / punch_hole path. As such, the caller |
| * must hold locks protecting against concurrent modifications of the |
| * radix tree (usually fs-private i_mmap_sem for writing). Since the |
| * caller has seen exceptional entry for this index, we better find it |
| * at that index as well... |
| */ |
| WARN_ON_ONCE(!ret); |
| return ret; |
| } |
| |
| /* |
| * Invalidate exceptional DAX entry if it is clean. |
| */ |
| int dax_invalidate_mapping_entry_sync(struct address_space *mapping, |
| pgoff_t index) |
| { |
| return __dax_invalidate_mapping_entry(mapping, index, false); |
| } |
| |
| static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev, |
| sector_t sector, size_t size, struct page *to, |
| unsigned long vaddr) |
| { |
| void *vto, *kaddr; |
| pgoff_t pgoff; |
| long rc; |
| int id; |
| |
| rc = bdev_dax_pgoff(bdev, sector, size, &pgoff); |
| if (rc) |
| return rc; |
| |
| id = dax_read_lock(); |
| rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, NULL); |
| if (rc < 0) { |
| dax_read_unlock(id); |
| return rc; |
| } |
| vto = kmap_atomic(to); |
| copy_user_page(vto, (void __force *)kaddr, vaddr, to); |
| kunmap_atomic(vto); |
| dax_read_unlock(id); |
| return 0; |
| } |
| |
| /* |
| * By this point grab_mapping_entry() has ensured that we have a locked entry |
| * of the appropriate size so we don't have to worry about downgrading PMDs to |
| * PTEs. If we happen to be trying to insert a PTE and there is a PMD |
| * already in the tree, we will skip the insertion and just dirty the PMD as |
| * appropriate. |
| */ |
| static void *dax_insert_mapping_entry(struct address_space *mapping, |
| struct vm_fault *vmf, |
| void *entry, pfn_t pfn_t, |
| unsigned long flags, bool dirty) |
| { |
| struct radix_tree_root *pages = &mapping->i_pages; |
| unsigned long pfn = pfn_t_to_pfn(pfn_t); |
| pgoff_t index = vmf->pgoff; |
| void *new_entry; |
| |
| if (dirty) |
| __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
| |
| if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_ZERO_PAGE)) { |
| /* we are replacing a zero page with block mapping */ |
| if (dax_is_pmd_entry(entry)) |
| unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR, |
| PG_PMD_NR, false); |
| else /* pte entry */ |
| unmap_mapping_pages(mapping, vmf->pgoff, 1, false); |
| } |
| |
| xa_lock_irq(pages); |
| new_entry = dax_radix_locked_entry(pfn, flags); |
| if (dax_entry_size(entry) != dax_entry_size(new_entry)) { |
| dax_disassociate_entry(entry, mapping, false); |
| dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address); |
| } |
| |
| if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { |
| /* |
| * Only swap our new entry into the radix tree if the current |
| * entry is a zero page or an empty entry. If a normal PTE or |
| * PMD entry is already in the tree, we leave it alone. This |
| * means that if we are trying to insert a PTE and the |
| * existing entry is a PMD, we will just leave the PMD in the |
| * tree and dirty it if necessary. |
| */ |
| struct radix_tree_node *node; |
| void **slot; |
| void *ret; |
| |
| ret = __radix_tree_lookup(pages, index, &node, &slot); |
| WARN_ON_ONCE(ret != entry); |
| __radix_tree_replace(pages, node, slot, |
| new_entry, NULL); |
| entry = new_entry; |
| } |
| |
| if (dirty) |
| radix_tree_tag_set(pages, index, PAGECACHE_TAG_DIRTY); |
| |
| xa_unlock_irq(pages); |
| return entry; |
| } |
| |
| static inline unsigned long |
| pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma) |
| { |
| unsigned long address; |
| |
| address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
| VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); |
| return address; |
| } |
| |
| /* Walk all mappings of a given index of a file and writeprotect them */ |
| static void dax_mapping_entry_mkclean(struct address_space *mapping, |
| pgoff_t index, unsigned long pfn) |
| { |
| struct vm_area_struct *vma; |
| pte_t pte, *ptep = NULL; |
| pmd_t *pmdp = NULL; |
| spinlock_t *ptl; |
| |
| i_mmap_lock_read(mapping); |
| vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { |
| unsigned long address, start, end; |
| |
| cond_resched(); |
| |
| if (!(vma->vm_flags & VM_SHARED)) |
| continue; |
| |
| address = pgoff_address(index, vma); |
| |
| /* |
| * Note because we provide start/end to follow_pte_pmd it will |
| * call mmu_notifier_invalidate_range_start() on our behalf |
| * before taking any lock. |
| */ |
| if (follow_pte_pmd(vma->vm_mm, address, &start, &end, &ptep, &pmdp, &ptl)) |
| continue; |
| |
| /* |
| * No need to call mmu_notifier_invalidate_range() as we are |
| * downgrading page table protection not changing it to point |
| * to a new page. |
| * |
| * See Documentation/vm/mmu_notifier.rst |
| */ |
| if (pmdp) { |
| #ifdef CONFIG_FS_DAX_PMD |
| pmd_t pmd; |
| |
| if (pfn != pmd_pfn(*pmdp)) |
| goto unlock_pmd; |
| if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp)) |
| goto unlock_pmd; |
| |
| flush_cache_page(vma, address, pfn); |
| pmd = pmdp_huge_clear_flush(vma, address, pmdp); |
| pmd = pmd_wrprotect(pmd); |
| pmd = pmd_mkclean(pmd); |
| set_pmd_at(vma->vm_mm, address, pmdp, pmd); |
| unlock_pmd: |
| #endif |
| spin_unlock(ptl); |
| } else { |
| if (pfn != pte_pfn(*ptep)) |
| goto unlock_pte; |
| if (!pte_dirty(*ptep) && !pte_write(*ptep)) |
| goto unlock_pte; |
| |
| flush_cache_page(vma, address, pfn); |
| pte = ptep_clear_flush(vma, address, ptep); |
| pte = pte_wrprotect(pte); |
| pte = pte_mkclean(pte); |
| set_pte_at(vma->vm_mm, address, ptep, pte); |
| unlock_pte: |
| pte_unmap_unlock(ptep, ptl); |
| } |
| |
| mmu_notifier_invalidate_range_end(vma->vm_mm, start, end); |
| } |
| i_mmap_unlock_read(mapping); |
| } |
| |
| static int dax_writeback_one(struct dax_device *dax_dev, |
| struct address_space *mapping, pgoff_t index, void *entry) |
| { |
| struct radix_tree_root *pages = &mapping->i_pages; |
| void *entry2, **slot; |
| unsigned long pfn; |
| long ret = 0; |
| size_t size; |
| |
| /* |
| * A page got tagged dirty in DAX mapping? Something is seriously |
| * wrong. |
| */ |
| if (WARN_ON(!radix_tree_exceptional_entry(entry))) |
| return -EIO; |
| |
| xa_lock_irq(pages); |
| entry2 = get_unlocked_mapping_entry(mapping, index, &slot); |
| /* Entry got punched out / reallocated? */ |
| if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2))) |
| goto put_unlocked; |
| /* |
| * Entry got reallocated elsewhere? No need to writeback. We have to |
| * compare pfns as we must not bail out due to difference in lockbit |
| * or entry type. |
| */ |
| if (dax_radix_pfn(entry2) != dax_radix_pfn(entry)) |
| goto put_unlocked; |
| if (WARN_ON_ONCE(dax_is_empty_entry(entry) || |
| dax_is_zero_entry(entry))) { |
| ret = -EIO; |
| goto put_unlocked; |
| } |
| |
| /* Another fsync thread may have already written back this entry */ |
| if (!radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE)) |
| goto put_unlocked; |
| /* Lock the entry to serialize with page faults */ |
| entry = lock_slot(mapping, slot); |
| /* |
| * We can clear the tag now but we have to be careful so that concurrent |
| * dax_writeback_one() calls for the same index cannot finish before we |
| * actually flush the caches. This is achieved as the calls will look |
| * at the entry only under the i_pages lock and once they do that |
| * they will see the entry locked and wait for it to unlock. |
| */ |
| radix_tree_tag_clear(pages, index, PAGECACHE_TAG_TOWRITE); |
| xa_unlock_irq(pages); |
| |
| /* |
| * Even if dax_writeback_mapping_range() was given a wbc->range_start |
| * in the middle of a PMD, the 'index' we are given will be aligned to |
| * the start index of the PMD, as will the pfn we pull from 'entry'. |
| * This allows us to flush for PMD_SIZE and not have to worry about |
| * partial PMD writebacks. |
| */ |
| pfn = dax_radix_pfn(entry); |
| size = PAGE_SIZE << dax_radix_order(entry); |
| |
| dax_mapping_entry_mkclean(mapping, index, pfn); |
| dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size); |
| /* |
| * After we have flushed the cache, we can clear the dirty tag. There |
| * cannot be new dirty data in the pfn after the flush has completed as |
| * the pfn mappings are writeprotected and fault waits for mapping |
| * entry lock. |
| */ |
| xa_lock_irq(pages); |
| radix_tree_tag_clear(pages, index, PAGECACHE_TAG_DIRTY); |
| xa_unlock_irq(pages); |
| trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT); |
| put_locked_mapping_entry(mapping, index); |
| return ret; |
| |
| put_unlocked: |
| put_unlocked_mapping_entry(mapping, index, entry2); |
| xa_unlock_irq(pages); |
| return ret; |
| } |
| |
| /* |
| * Flush the mapping to the persistent domain within the byte range of [start, |
| * end]. This is required by data integrity operations to ensure file data is |
| * on persistent storage prior to completion of the operation. |
| */ |
| int dax_writeback_mapping_range(struct address_space *mapping, |
| struct block_device *bdev, struct writeback_control *wbc) |
| { |
| struct inode *inode = mapping->host; |
| pgoff_t start_index, end_index; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| struct dax_device *dax_dev; |
| struct pagevec pvec; |
| bool done = false; |
| int i, ret = 0; |
| |
| if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) |
| return -EIO; |
| |
| if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) |
| return 0; |
| |
| dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); |
| if (!dax_dev) |
| return -EIO; |
| |
| start_index = wbc->range_start >> PAGE_SHIFT; |
| end_index = wbc->range_end >> PAGE_SHIFT; |
| |
| trace_dax_writeback_range(inode, start_index, end_index); |
| |
| tag_pages_for_writeback(mapping, start_index, end_index); |
| |
| pagevec_init(&pvec); |
| while (!done) { |
| pvec.nr = find_get_entries_tag(mapping, start_index, |
| PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE, |
| pvec.pages, indices); |
| |
| if (pvec.nr == 0) |
| break; |
| |
| for (i = 0; i < pvec.nr; i++) { |
| if (indices[i] > end_index) { |
| done = true; |
| break; |
| } |
| |
| ret = dax_writeback_one(dax_dev, mapping, indices[i], |
| pvec.pages[i]); |
| if (ret < 0) { |
| mapping_set_error(mapping, ret); |
| goto out; |
| } |
| } |
| start_index = indices[pvec.nr - 1] + 1; |
| } |
| out: |
| put_dax(dax_dev); |
| trace_dax_writeback_range_done(inode, start_index, end_index); |
| return (ret < 0 ? ret : 0); |
| } |
| EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); |
| |
| static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) |
| { |
| return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9; |
| } |
| |
| static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, |
| pfn_t *pfnp) |
| { |
| const sector_t sector = dax_iomap_sector(iomap, pos); |
| pgoff_t pgoff; |
| int id, rc; |
| long length; |
| |
| rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff); |
| if (rc) |
| return rc; |
| id = dax_read_lock(); |
| length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), |
| NULL, pfnp); |
| if (length < 0) { |
| rc = length; |
| goto out; |
| } |
| rc = -EINVAL; |
| if (PFN_PHYS(length) < size) |
| goto out; |
| if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1)) |
| goto out; |
| /* For larger pages we need devmap */ |
| if (length > 1 && !pfn_t_devmap(*pfnp)) |
| goto out; |
| rc = 0; |
| out: |
| dax_read_unlock(id); |
| return rc; |
| } |
| |
| /* |
| * The user has performed a load from a hole in the file. Allocating a new |
| * page in the file would cause excessive storage usage for workloads with |
| * sparse files. Instead we insert a read-only mapping of the 4k zero page. |
| * If this page is ever written to we will re-fault and change the mapping to |
| * point to real DAX storage instead. |
| */ |
| static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry, |
| struct vm_fault *vmf) |
| { |
| struct inode *inode = mapping->host; |
| unsigned long vaddr = vmf->address; |
| pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr)); |
| vm_fault_t ret; |
| |
| dax_insert_mapping_entry(mapping, vmf, entry, pfn, RADIX_DAX_ZERO_PAGE, |
| false); |
| ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); |
| trace_dax_load_hole(inode, vmf, ret); |
| return ret; |
| } |
| |
| static bool dax_range_is_aligned(struct block_device *bdev, |
| unsigned int offset, unsigned int length) |
| { |
| unsigned short sector_size = bdev_logical_block_size(bdev); |
| |
| if (!IS_ALIGNED(offset, sector_size)) |
| return false; |
| if (!IS_ALIGNED(length, sector_size)) |
| return false; |
| |
| return true; |
| } |
| |
| int __dax_zero_page_range(struct block_device *bdev, |
| struct dax_device *dax_dev, sector_t sector, |
| unsigned int offset, unsigned int size) |
| { |
| if (dax_range_is_aligned(bdev, offset, size)) { |
| sector_t start_sector = sector + (offset >> 9); |
| |
| return blkdev_issue_zeroout(bdev, start_sector, |
| size >> 9, GFP_NOFS, 0); |
| } else { |
| pgoff_t pgoff; |
| long rc, id; |
| void *kaddr; |
| |
| rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff); |
| if (rc) |
| return rc; |
| |
| id = dax_read_lock(); |
| rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL); |
| if (rc < 0) { |
| dax_read_unlock(id); |
| return rc; |
| } |
| memset(kaddr + offset, 0, size); |
| dax_flush(dax_dev, kaddr + offset, size); |
| dax_read_unlock(id); |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(__dax_zero_page_range); |
| |
| static loff_t |
| dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
| struct iomap *iomap) |
| { |
| struct block_device *bdev = iomap->bdev; |
| struct dax_device *dax_dev = iomap->dax_dev; |
| struct iov_iter *iter = data; |
| loff_t end = pos + length, done = 0; |
| ssize_t ret = 0; |
| size_t xfer; |
| int id; |
| |
| if (iov_iter_rw(iter) == READ) { |
| end = min(end, i_size_read(inode)); |
| if (pos >= end) |
| return 0; |
| |
| if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) |
| return iov_iter_zero(min(length, end - pos), iter); |
| } |
| |
| if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) |
| return -EIO; |
| |
| /* |
| * Write can allocate block for an area which has a hole page mapped |
| * into page tables. We have to tear down these mappings so that data |
| * written by write(2) is visible in mmap. |
| */ |
| if (iomap->flags & IOMAP_F_NEW) { |
| invalidate_inode_pages2_range(inode->i_mapping, |
| pos >> PAGE_SHIFT, |
| (end - 1) >> PAGE_SHIFT); |
| } |
| |
| id = dax_read_lock(); |
| while (pos < end) { |
| unsigned offset = pos & (PAGE_SIZE - 1); |
| const size_t size = ALIGN(length + offset, PAGE_SIZE); |
| const sector_t sector = dax_iomap_sector(iomap, pos); |
| ssize_t map_len; |
| pgoff_t pgoff; |
| void *kaddr; |
| |
| if (fatal_signal_pending(current)) { |
| ret = -EINTR; |
| break; |
| } |
| |
| ret = bdev_dax_pgoff(bdev, sector, size, &pgoff); |
| if (ret) |
| break; |
| |
| map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), |
| &kaddr, NULL); |
| if (map_len < 0) { |
| ret = map_len; |
| break; |
| } |
| |
| map_len = PFN_PHYS(map_len); |
| kaddr += offset; |
| map_len -= offset; |
| if (map_len > end - pos) |
| map_len = end - pos; |
| |
| /* |
| * The userspace address for the memory copy has already been |
| * validated via access_ok() in either vfs_read() or |
| * vfs_write(), depending on which operation we are doing. |
| */ |
| if (iov_iter_rw(iter) == WRITE) |
| xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, |
| map_len, iter); |
| else |
| xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr, |
| map_len, iter); |
| |
| pos += xfer; |
| length -= xfer; |
| done += xfer; |
| |
| if (xfer == 0) |
| ret = -EFAULT; |
| if (xfer < map_len) |
| break; |
| } |
| dax_read_unlock(id); |
| |
| return done ? done : ret; |
| } |
| |
| /** |
| * dax_iomap_rw - Perform I/O to a DAX file |
| * @iocb: The control block for this I/O |
| * @iter: The addresses to do I/O from or to |
| * @ops: iomap ops passed from the file system |
| * |
| * This function performs read and write operations to directly mapped |
| * persistent memory. The callers needs to take care of read/write exclusion |
| * and evicting any page cache pages in the region under I/O. |
| */ |
| ssize_t |
| dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, |
| const struct iomap_ops *ops) |
| { |
| struct address_space *mapping = iocb->ki_filp->f_mapping; |
| struct inode *inode = mapping->host; |
| loff_t pos = iocb->ki_pos, ret = 0, done = 0; |
| unsigned flags = 0; |
| |
| if (iov_iter_rw(iter) == WRITE) { |
| lockdep_assert_held_exclusive(&inode->i_rwsem); |
| flags |= IOMAP_WRITE; |
| } else { |
| lockdep_assert_held(&inode->i_rwsem); |
| } |
| |
| while (iov_iter_count(iter)) { |
| ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops, |
| iter, dax_iomap_actor); |
| if (ret <= 0) |
| break; |
| pos += ret; |
| done += ret; |
| } |
| |
| iocb->ki_pos += done; |
| return done ? done : ret; |
| } |
| EXPORT_SYMBOL_GPL(dax_iomap_rw); |
| |
| static vm_fault_t dax_fault_return(int error) |
| { |
| if (error == 0) |
| return VM_FAULT_NOPAGE; |
| if (error == -ENOMEM) |
| return VM_FAULT_OOM; |
| return VM_FAULT_SIGBUS; |
| } |
| |
| /* |
| * MAP_SYNC on a dax mapping guarantees dirty metadata is |
| * flushed on write-faults (non-cow), but not read-faults. |
| */ |
| static bool dax_fault_is_synchronous(unsigned long flags, |
| struct vm_area_struct *vma, struct iomap *iomap) |
| { |
| return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC) |
| && (iomap->flags & IOMAP_F_DIRTY); |
| } |
| |
| static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, |
| int *iomap_errp, const struct iomap_ops *ops) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| struct inode *inode = mapping->host; |
| unsigned long vaddr = vmf->address; |
| loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; |
| struct iomap iomap = { 0 }; |
| unsigned flags = IOMAP_FAULT; |
| int error, major = 0; |
| bool write = vmf->flags & FAULT_FLAG_WRITE; |
| bool sync; |
| vm_fault_t ret = 0; |
| void *entry; |
| pfn_t pfn; |
| |
| trace_dax_pte_fault(inode, vmf, ret); |
| /* |
| * Check whether offset isn't beyond end of file now. Caller is supposed |
| * to hold locks serializing us with truncate / punch hole so this is |
| * a reliable test. |
| */ |
| if (pos >= i_size_read(inode)) { |
| ret = VM_FAULT_SIGBUS; |
| goto out; |
| } |
| |
| if (write && !vmf->cow_page) |
| flags |= IOMAP_WRITE; |
| |
| entry = grab_mapping_entry(mapping, vmf->pgoff, 0); |
| if (IS_ERR(entry)) { |
| ret = dax_fault_return(PTR_ERR(entry)); |
| goto out; |
| } |
| |
| /* |
| * It is possible, particularly with mixed reads & writes to private |
| * mappings, that we have raced with a PMD fault that overlaps with |
| * the PTE we need to set up. If so just return and the fault will be |
| * retried. |
| */ |
| if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) { |
| ret = VM_FAULT_NOPAGE; |
| goto unlock_entry; |
| } |
| |
| /* |
| * Note that we don't bother to use iomap_apply here: DAX required |
| * the file system block size to be equal the page size, which means |
| * that we never have to deal with more than a single extent here. |
| */ |
| error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); |
| if (iomap_errp) |
| *iomap_errp = error; |
| if (error) { |
| ret = dax_fault_return(error); |
| goto unlock_entry; |
| } |
| if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { |
| error = -EIO; /* fs corruption? */ |
| goto error_finish_iomap; |
| } |
| |
| if (vmf->cow_page) { |
| sector_t sector = dax_iomap_sector(&iomap, pos); |
| |
| switch (iomap.type) { |
| case IOMAP_HOLE: |
| case IOMAP_UNWRITTEN: |
| clear_user_highpage(vmf->cow_page, vaddr); |
| break; |
| case IOMAP_MAPPED: |
| error = copy_user_dax(iomap.bdev, iomap.dax_dev, |
| sector, PAGE_SIZE, vmf->cow_page, vaddr); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| error = -EIO; |
| break; |
| } |
| |
| if (error) |
| goto error_finish_iomap; |
| |
| __SetPageUptodate(vmf->cow_page); |
| ret = finish_fault(vmf); |
| if (!ret) |
| ret = VM_FAULT_DONE_COW; |
| goto finish_iomap; |
| } |
| |
| sync = dax_fault_is_synchronous(flags, vma, &iomap); |
| |
| switch (iomap.type) { |
| case IOMAP_MAPPED: |
| if (iomap.flags & IOMAP_F_NEW) { |
| count_vm_event(PGMAJFAULT); |
| count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); |
| major = VM_FAULT_MAJOR; |
| } |
| error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn); |
| if (error < 0) |
| goto error_finish_iomap; |
| |
| entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn, |
| 0, write && !sync); |
| |
| /* |
| * If we are doing synchronous page fault and inode needs fsync, |
| * we can insert PTE into page tables only after that happens. |
| * Skip insertion for now and return the pfn so that caller can |
| * insert it after fsync is done. |
| */ |
| if (sync) { |
| if (WARN_ON_ONCE(!pfnp)) { |
| error = -EIO; |
| goto error_finish_iomap; |
| } |
| *pfnp = pfn; |
| ret = VM_FAULT_NEEDDSYNC | major; |
| goto finish_iomap; |
| } |
| trace_dax_insert_mapping(inode, vmf, entry); |
| if (write) |
| ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn); |
| else |
| ret = vmf_insert_mixed(vma, vaddr, pfn); |
| |
| goto finish_iomap; |
| case IOMAP_UNWRITTEN: |
| case IOMAP_HOLE: |
| if (!write) { |
| ret = dax_load_hole(mapping, entry, vmf); |
| goto finish_iomap; |
| } |
| /*FALLTHRU*/ |
| default: |
| WARN_ON_ONCE(1); |
| error = -EIO; |
| break; |
| } |
| |
| error_finish_iomap: |
| ret = dax_fault_return(error); |
| finish_iomap: |
| if (ops->iomap_end) { |
| int copied = PAGE_SIZE; |
| |
| if (ret & VM_FAULT_ERROR) |
| copied = 0; |
| /* |
| * The fault is done by now and there's no way back (other |
| * thread may be already happily using PTE we have installed). |
| * Just ignore error from ->iomap_end since we cannot do much |
| * with it. |
| */ |
| ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap); |
| } |
| unlock_entry: |
| put_locked_mapping_entry(mapping, vmf->pgoff); |
| out: |
| trace_dax_pte_fault_done(inode, vmf, ret); |
| return ret | major; |
| } |
| |
| #ifdef CONFIG_FS_DAX_PMD |
| static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap, |
| void *entry) |
| { |
| struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
| unsigned long pmd_addr = vmf->address & PMD_MASK; |
| struct inode *inode = mapping->host; |
| struct page *zero_page; |
| void *ret = NULL; |
| spinlock_t *ptl; |
| pmd_t pmd_entry; |
| pfn_t pfn; |
| |
| zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); |
| |
| if (unlikely(!zero_page)) |
| goto fallback; |
| |
| pfn = page_to_pfn_t(zero_page); |
| ret = dax_insert_mapping_entry(mapping, vmf, entry, pfn, |
| RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE, false); |
| |
| ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); |
| if (!pmd_none(*(vmf->pmd))) { |
| spin_unlock(ptl); |
| goto fallback; |
| } |
| |
| pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); |
| pmd_entry = pmd_mkhuge(pmd_entry); |
| set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); |
| spin_unlock(ptl); |
| trace_dax_pmd_load_hole(inode, vmf, zero_page, ret); |
| return VM_FAULT_NOPAGE; |
| |
| fallback: |
| trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, ret); |
| return VM_FAULT_FALLBACK; |
| } |
| |
| static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, |
| const struct iomap_ops *ops) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| unsigned long pmd_addr = vmf->address & PMD_MASK; |
| bool write = vmf->flags & FAULT_FLAG_WRITE; |
| bool sync; |
| unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; |
| struct inode *inode = mapping->host; |
| vm_fault_t result = VM_FAULT_FALLBACK; |
| struct iomap iomap = { 0 }; |
| pgoff_t max_pgoff, pgoff; |
| void *entry; |
| loff_t pos; |
| int error; |
| pfn_t pfn; |
| |
| /* |
| * Check whether offset isn't beyond end of file now. Caller is |
| * supposed to hold locks serializing us with truncate / punch hole so |
| * this is a reliable test. |
| */ |
| pgoff = linear_page_index(vma, pmd_addr); |
| max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); |
| |
| trace_dax_pmd_fault(inode, vmf, max_pgoff, 0); |
| |
| /* |
| * Make sure that the faulting address's PMD offset (color) matches |
| * the PMD offset from the start of the file. This is necessary so |
| * that a PMD range in the page table overlaps exactly with a PMD |
| * range in the radix tree. |
| */ |
| if ((vmf->pgoff & PG_PMD_COLOUR) != |
| ((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR)) |
| goto fallback; |
| |
| /* Fall back to PTEs if we're going to COW */ |
| if (write && !(vma->vm_flags & VM_SHARED)) |
| goto fallback; |
| |
| /* If the PMD would extend outside the VMA */ |
| if (pmd_addr < vma->vm_start) |
| goto fallback; |
| if ((pmd_addr + PMD_SIZE) > vma->vm_end) |
| goto fallback; |
| |
| if (pgoff >= max_pgoff) { |
| result = VM_FAULT_SIGBUS; |
| goto out; |
| } |
| |
| /* If the PMD would extend beyond the file size */ |
| if ((pgoff | PG_PMD_COLOUR) >= max_pgoff) |
| goto fallback; |
| |
| /* |
| * grab_mapping_entry() will make sure we get a 2MiB empty entry, a |
| * 2MiB zero page entry or a DAX PMD. If it can't (because a 4k page |
| * is already in the tree, for instance), it will return -EEXIST and |
| * we just fall back to 4k entries. |
| */ |
| entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD); |
| if (IS_ERR(entry)) |
| goto fallback; |
| |
| /* |
| * It is possible, particularly with mixed reads & writes to private |
| * mappings, that we have raced with a PTE fault that overlaps with |
| * the PMD we need to set up. If so just return and the fault will be |
| * retried. |
| */ |
| if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) && |
| !pmd_devmap(*vmf->pmd)) { |
| result = 0; |
| goto unlock_entry; |
| } |
| |
| /* |
| * Note that we don't use iomap_apply here. We aren't doing I/O, only |
| * setting up a mapping, so really we're using iomap_begin() as a way |
| * to look up our filesystem block. |
| */ |
| pos = (loff_t)pgoff << PAGE_SHIFT; |
| error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap); |
| if (error) |
| goto unlock_entry; |
| |
| if (iomap.offset + iomap.length < pos + PMD_SIZE) |
| goto finish_iomap; |
| |
| sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap); |
| |
| switch (iomap.type) { |
| case IOMAP_MAPPED: |
| error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn); |
| if (error < 0) |
| goto finish_iomap; |
| |
| entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn, |
| RADIX_DAX_PMD, write && !sync); |
| |
| /* |
| * If we are doing synchronous page fault and inode needs fsync, |
| * we can insert PMD into page tables only after that happens. |
| * Skip insertion for now and return the pfn so that caller can |
| * insert it after fsync is done. |
| */ |
| if (sync) { |
| if (WARN_ON_ONCE(!pfnp)) |
| goto finish_iomap; |
| *pfnp = pfn; |
| result = VM_FAULT_NEEDDSYNC; |
| goto finish_iomap; |
| } |
| |
| trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry); |
| result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn, |
| write); |
| break; |
| case IOMAP_UNWRITTEN: |
| case IOMAP_HOLE: |
| if (WARN_ON_ONCE(write)) |
| break; |
| result = dax_pmd_load_hole(vmf, &iomap, entry); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| break; |
| } |
| |
| finish_iomap: |
| if (ops->iomap_end) { |
| int copied = PMD_SIZE; |
| |
| if (result == VM_FAULT_FALLBACK) |
| copied = 0; |
| /* |
| * The fault is done by now and there's no way back (other |
| * thread may be already happily using PMD we have installed). |
| * Just ignore error from ->iomap_end since we cannot do much |
| * with it. |
| */ |
| ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags, |
| &iomap); |
| } |
| unlock_entry: |
| put_locked_mapping_entry(mapping, pgoff); |
| fallback: |
| if (result == VM_FAULT_FALLBACK) { |
| split_huge_pmd(vma, vmf->pmd, vmf->address); |
| count_vm_event(THP_FAULT_FALLBACK); |
| } |
| out: |
| trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result); |
| return result; |
| } |
| #else |
| static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, |
| const struct iomap_ops *ops) |
| { |
| return VM_FAULT_FALLBACK; |
| } |
| #endif /* CONFIG_FS_DAX_PMD */ |
| |
| /** |
| * dax_iomap_fault - handle a page fault on a DAX file |
| * @vmf: The description of the fault |
| * @pe_size: Size of the page to fault in |
| * @pfnp: PFN to insert for synchronous faults if fsync is required |
| * @iomap_errp: Storage for detailed error code in case of error |
| * @ops: Iomap ops passed from the file system |
| * |
| * When a page fault occurs, filesystems may call this helper in |
| * their fault handler for DAX files. dax_iomap_fault() assumes the caller |
| * has done all the necessary locking for page fault to proceed |
| * successfully. |
| */ |
| vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size, |
| pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops) |
| { |
| switch (pe_size) { |
| case PE_SIZE_PTE: |
| return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops); |
| case PE_SIZE_PMD: |
| return dax_iomap_pmd_fault(vmf, pfnp, ops); |
| default: |
| return VM_FAULT_FALLBACK; |
| } |
| } |
| EXPORT_SYMBOL_GPL(dax_iomap_fault); |
| |
| /** |
| * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables |
| * @vmf: The description of the fault |
| * @pe_size: Size of entry to be inserted |
| * @pfn: PFN to insert |
| * |
| * This function inserts writeable PTE or PMD entry into page tables for mmaped |
| * DAX file. It takes care of marking corresponding radix tree entry as dirty |
| * as well. |
| */ |
| static vm_fault_t dax_insert_pfn_mkwrite(struct vm_fault *vmf, |
| enum page_entry_size pe_size, |
| pfn_t pfn) |
| { |
| struct address_space *mapping = vmf->vma->vm_file->f_mapping; |
| void *entry, **slot; |
| pgoff_t index = vmf->pgoff; |
| vm_fault_t ret; |
| |
| xa_lock_irq(&mapping->i_pages); |
| entry = get_unlocked_mapping_entry(mapping, index, &slot); |
| /* Did we race with someone splitting entry or so? */ |
| if (!entry || |
| (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) || |
| (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) { |
| put_unlocked_mapping_entry(mapping, index, entry); |
| xa_unlock_irq(&mapping->i_pages); |
| trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf, |
| VM_FAULT_NOPAGE); |
| return VM_FAULT_NOPAGE; |
| } |
| radix_tree_tag_set(&mapping->i_pages, index, PAGECACHE_TAG_DIRTY); |
| entry = lock_slot(mapping, slot); |
| xa_unlock_irq(&mapping->i_pages); |
| switch (pe_size) { |
| case PE_SIZE_PTE: |
| ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); |
| break; |
| #ifdef CONFIG_FS_DAX_PMD |
| case PE_SIZE_PMD: |
| ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, |
| pfn, true); |
| break; |
| #endif |
| default: |
| ret = VM_FAULT_FALLBACK; |
| } |
| put_locked_mapping_entry(mapping, index); |
| trace_dax_insert_pfn_mkwrite(mapping->host, vmf, ret); |
| return ret; |
| } |
| |
| /** |
| * dax_finish_sync_fault - finish synchronous page fault |
| * @vmf: The description of the fault |
| * @pe_size: Size of entry to be inserted |
| * @pfn: PFN to insert |
| * |
| * This function ensures that the file range touched by the page fault is |
| * stored persistently on the media and handles inserting of appropriate page |
| * table entry. |
| */ |
| vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf, |
| enum page_entry_size pe_size, pfn_t pfn) |
| { |
| int err; |
| loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT; |
| size_t len = 0; |
| |
| if (pe_size == PE_SIZE_PTE) |
| len = PAGE_SIZE; |
| else if (pe_size == PE_SIZE_PMD) |
| len = PMD_SIZE; |
| else |
| WARN_ON_ONCE(1); |
| err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1); |
| if (err) |
| return VM_FAULT_SIGBUS; |
| return dax_insert_pfn_mkwrite(vmf, pe_size, pfn); |
| } |
| EXPORT_SYMBOL_GPL(dax_finish_sync_fault); |