| /* |
| * 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/pmem.h> |
| #include <linux/sched.h> |
| #include <linux/uio.h> |
| #include <linux/vmstat.h> |
| #include <linux/pfn_t.h> |
| #include <linux/sizes.h> |
| #include <linux/iomap.h> |
| #include "internal.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) |
| |
| 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); |
| |
| static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax) |
| { |
| struct request_queue *q = bdev->bd_queue; |
| long rc = -EIO; |
| |
| dax->addr = ERR_PTR(-EIO); |
| if (blk_queue_enter(q, true) != 0) |
| return rc; |
| |
| rc = bdev_direct_access(bdev, dax); |
| if (rc < 0) { |
| dax->addr = ERR_PTR(rc); |
| blk_queue_exit(q); |
| return rc; |
| } |
| return rc; |
| } |
| |
| static void dax_unmap_atomic(struct block_device *bdev, |
| const struct blk_dax_ctl *dax) |
| { |
| if (IS_ERR(dax->addr)) |
| return; |
| blk_queue_exit(bdev->bd_queue); |
| } |
| |
| 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_HZP; |
| } |
| |
| static int dax_is_empty_entry(void *entry) |
| { |
| return (unsigned long)entry & RADIX_DAX_EMPTY; |
| } |
| |
| struct page *read_dax_sector(struct block_device *bdev, sector_t n) |
| { |
| struct page *page = alloc_pages(GFP_KERNEL, 0); |
| struct blk_dax_ctl dax = { |
| .size = PAGE_SIZE, |
| .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), |
| }; |
| long rc; |
| |
| if (!page) |
| return ERR_PTR(-ENOMEM); |
| |
| rc = dax_map_atomic(bdev, &dax); |
| if (rc < 0) |
| return ERR_PTR(rc); |
| memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); |
| dax_unmap_atomic(bdev, &dax); |
| return page; |
| } |
| |
| /* |
| * DAX radix tree locking |
| */ |
| struct exceptional_entry_key { |
| struct address_space *mapping; |
| pgoff_t entry_start; |
| }; |
| |
| struct wait_exceptional_entry_queue { |
| wait_queue_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 &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1); |
| |
| 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_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); |
| } |
| |
| /* |
| * Check whether the given slot is locked. The function must be called with |
| * mapping->tree_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->tree_lock); |
| return entry & RADIX_DAX_ENTRY_LOCK; |
| } |
| |
| /* |
| * Mark the given slot is locked. The function must be called with |
| * mapping->tree_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->tree_lock); |
| |
| entry |= RADIX_DAX_ENTRY_LOCK; |
| radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); |
| return (void *)entry; |
| } |
| |
| /* |
| * Mark the given slot is unlocked. The function must be called with |
| * mapping->tree_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->tree_lock); |
| |
| entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; |
| radix_tree_replace_slot(&mapping->page_tree, 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. |
| * |
| * The function must be called with mapping->tree_lock held. |
| */ |
| static void *get_unlocked_mapping_entry(struct address_space *mapping, |
| pgoff_t index, void ***slotp) |
| { |
| 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 (;;) { |
| entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, |
| &slot); |
| if (!entry || !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); |
| spin_unlock_irq(&mapping->tree_lock); |
| schedule(); |
| finish_wait(wq, &ewait.wait); |
| spin_lock_irq(&mapping->tree_lock); |
| } |
| } |
| |
| static void put_locked_mapping_entry(struct address_space *mapping, |
| pgoff_t index, void *entry) |
| { |
| if (!radix_tree_exceptional_entry(entry)) { |
| unlock_page(entry); |
| put_page(entry); |
| } else { |
| dax_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 (!radix_tree_exceptional_entry(entry)) |
| return; |
| |
| /* We have to wake up next waiter for the radix tree entry lock */ |
| dax_wake_mapping_entry_waiter(mapping, index, entry, false); |
| } |
| |
| /* |
| * Find radix tree entry at given index. If it points to a page, return with |
| * the page locked. If it points to the exceptional entry, return with the |
| * radix tree entry locked. If the radix tree doesn't contain given index, |
| * create 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 (either zero pages or DAX 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: |
| spin_lock_irq(&mapping->tree_lock); |
| entry = get_unlocked_mapping_entry(mapping, index, &slot); |
| |
| if (entry) { |
| if (size_flag & RADIX_DAX_PMD) { |
| if (!radix_tree_exceptional_entry(entry) || |
| 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 (radix_tree_exceptional_entry(entry) && |
| 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 |
| * mapping->tree_lock. |
| */ |
| entry = lock_slot(mapping, slot); |
| } |
| |
| spin_unlock_irq(&mapping->tree_lock); |
| /* |
| * 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_range(mapping, |
| (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); |
| |
| err = radix_tree_preload( |
| mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); |
| if (err) { |
| if (pmd_downgrade) |
| put_locked_mapping_entry(mapping, index, entry); |
| return ERR_PTR(err); |
| } |
| spin_lock_irq(&mapping->tree_lock); |
| |
| if (pmd_downgrade) { |
| radix_tree_delete(&mapping->page_tree, 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->page_tree, index, |
| dax_radix_order(entry), entry); |
| radix_tree_preload_end(); |
| if (err) { |
| spin_unlock_irq(&mapping->tree_lock); |
| /* |
| * Someone already created the entry? This is a |
| * normal failure when inserting PMDs in a range |
| * that already contains PTEs. In that case we want |
| * to return -EEXIST immediately. |
| */ |
| if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD)) |
| goto restart; |
| /* |
| * Our insertion of a DAX PMD entry failed, most |
| * likely because 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++; |
| spin_unlock_irq(&mapping->tree_lock); |
| return entry; |
| } |
| /* Normal page in radix tree? */ |
| if (!radix_tree_exceptional_entry(entry)) { |
| struct page *page = entry; |
| |
| get_page(page); |
| spin_unlock_irq(&mapping->tree_lock); |
| lock_page(page); |
| /* Page got truncated? Retry... */ |
| if (unlikely(page->mapping != mapping)) { |
| unlock_page(page); |
| put_page(page); |
| goto restart; |
| } |
| return page; |
| } |
| entry = lock_slot(mapping, slot); |
| out_unlock: |
| spin_unlock_irq(&mapping->tree_lock); |
| return entry; |
| } |
| |
| /* |
| * We do not necessarily hold the mapping->tree_lock when we call this |
| * function so it is possible that 'entry' is no longer a valid item in the |
| * radix tree. This is okay because all we really need to do is to find the |
| * correct waitqueue where tasks might be waiting for that old 'entry' and |
| * wake them. |
| */ |
| 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 mapping->tree_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); |
| } |
| |
| void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index) |
| { |
| void *entry, **slot; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); |
| if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) || |
| !slot_locked(mapping, slot))) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return; |
| } |
| unlock_slot(mapping, slot); |
| spin_unlock_irq(&mapping->tree_lock); |
| dax_wake_mapping_entry_waiter(mapping, index, entry, false); |
| } |
| |
| /* |
| * 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) |
| { |
| void *entry; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| entry = get_unlocked_mapping_entry(mapping, index, NULL); |
| /* |
| * 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... |
| */ |
| if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry))) { |
| spin_unlock_irq(&mapping->tree_lock); |
| return 0; |
| } |
| radix_tree_delete(&mapping->page_tree, index); |
| mapping->nrexceptional--; |
| spin_unlock_irq(&mapping->tree_lock); |
| dax_wake_mapping_entry_waiter(mapping, index, entry, true); |
| |
| return 1; |
| } |
| |
| /* |
| * 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. We allocate a page cache page instead. |
| * We'll kick it out of the page cache if it's ever written to, |
| * otherwise it will simply fall out of the page cache under memory |
| * pressure without ever having been dirtied. |
| */ |
| static int dax_load_hole(struct address_space *mapping, void *entry, |
| struct vm_fault *vmf) |
| { |
| struct page *page; |
| |
| /* Hole page already exists? Return it... */ |
| if (!radix_tree_exceptional_entry(entry)) { |
| vmf->page = entry; |
| return VM_FAULT_LOCKED; |
| } |
| |
| /* This will replace locked radix tree entry with a hole page */ |
| page = find_or_create_page(mapping, vmf->pgoff, |
| vmf->gfp_mask | __GFP_ZERO); |
| if (!page) { |
| put_locked_mapping_entry(mapping, vmf->pgoff, entry); |
| return VM_FAULT_OOM; |
| } |
| vmf->page = page; |
| return VM_FAULT_LOCKED; |
| } |
| |
| static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, |
| struct page *to, unsigned long vaddr) |
| { |
| struct blk_dax_ctl dax = { |
| .sector = sector, |
| .size = size, |
| }; |
| void *vto; |
| |
| if (dax_map_atomic(bdev, &dax) < 0) |
| return PTR_ERR(dax.addr); |
| vto = kmap_atomic(to); |
| copy_user_page(vto, (void __force *)dax.addr, vaddr, to); |
| kunmap_atomic(vto); |
| dax_unmap_atomic(bdev, &dax); |
| 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, sector_t sector, |
| unsigned long flags) |
| { |
| struct radix_tree_root *page_tree = &mapping->page_tree; |
| int error = 0; |
| bool hole_fill = false; |
| void *new_entry; |
| pgoff_t index = vmf->pgoff; |
| |
| if (vmf->flags & FAULT_FLAG_WRITE) |
| __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
| |
| /* Replacing hole page with block mapping? */ |
| if (!radix_tree_exceptional_entry(entry)) { |
| hole_fill = true; |
| /* |
| * Unmap the page now before we remove it from page cache below. |
| * The page is locked so it cannot be faulted in again. |
| */ |
| unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT, |
| PAGE_SIZE, 0); |
| error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM); |
| if (error) |
| return ERR_PTR(error); |
| } else if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_HZP)) { |
| /* replacing huge zero page with PMD block mapping */ |
| unmap_mapping_range(mapping, |
| (vmf->pgoff << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); |
| } |
| |
| spin_lock_irq(&mapping->tree_lock); |
| new_entry = dax_radix_locked_entry(sector, flags); |
| |
| if (hole_fill) { |
| __delete_from_page_cache(entry, NULL); |
| /* Drop pagecache reference */ |
| put_page(entry); |
| error = __radix_tree_insert(page_tree, index, |
| dax_radix_order(new_entry), new_entry); |
| if (error) { |
| new_entry = ERR_PTR(error); |
| goto unlock; |
| } |
| mapping->nrexceptional++; |
| } else 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(page_tree, index, &node, &slot); |
| WARN_ON_ONCE(ret != entry); |
| __radix_tree_replace(page_tree, node, slot, |
| new_entry, NULL, NULL); |
| } |
| if (vmf->flags & FAULT_FLAG_WRITE) |
| radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); |
| unlock: |
| spin_unlock_irq(&mapping->tree_lock); |
| if (hole_fill) { |
| radix_tree_preload_end(); |
| /* |
| * We don't need hole page anymore, it has been replaced with |
| * locked radix tree entry now. |
| */ |
| if (mapping->a_ops->freepage) |
| mapping->a_ops->freepage(entry); |
| unlock_page(entry); |
| put_page(entry); |
| } |
| return new_entry; |
| } |
| |
| static int dax_writeback_one(struct block_device *bdev, |
| struct address_space *mapping, pgoff_t index, void *entry) |
| { |
| struct radix_tree_root *page_tree = &mapping->page_tree; |
| struct radix_tree_node *node; |
| struct blk_dax_ctl dax; |
| void **slot; |
| int ret = 0; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| /* |
| * Regular page slots are stabilized by the page lock even |
| * without the tree itself locked. These unlocked entries |
| * need verification under the tree lock. |
| */ |
| if (!__radix_tree_lookup(page_tree, index, &node, &slot)) |
| goto unlock; |
| if (*slot != entry) |
| goto unlock; |
| |
| /* another fsync thread may have already written back this entry */ |
| if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) |
| goto unlock; |
| |
| if (WARN_ON_ONCE(dax_is_empty_entry(entry) || |
| dax_is_zero_entry(entry))) { |
| ret = -EIO; |
| goto unlock; |
| } |
| |
| /* |
| * 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 sector we pull from |
| * 'entry'. This allows us to flush for PMD_SIZE and not have to |
| * worry about partial PMD writebacks. |
| */ |
| dax.sector = dax_radix_sector(entry); |
| dax.size = PAGE_SIZE << dax_radix_order(entry); |
| spin_unlock_irq(&mapping->tree_lock); |
| |
| /* |
| * We cannot hold tree_lock while calling dax_map_atomic() because it |
| * eventually calls cond_resched(). |
| */ |
| ret = dax_map_atomic(bdev, &dax); |
| if (ret < 0) |
| return ret; |
| |
| if (WARN_ON_ONCE(ret < dax.size)) { |
| ret = -EIO; |
| goto unmap; |
| } |
| |
| wb_cache_pmem(dax.addr, dax.size); |
| |
| spin_lock_irq(&mapping->tree_lock); |
| radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); |
| spin_unlock_irq(&mapping->tree_lock); |
| unmap: |
| dax_unmap_atomic(bdev, &dax); |
| return ret; |
| |
| unlock: |
| spin_unlock_irq(&mapping->tree_lock); |
| 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 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; |
| |
| start_index = wbc->range_start >> PAGE_SHIFT; |
| end_index = wbc->range_end >> PAGE_SHIFT; |
| |
| tag_pages_for_writeback(mapping, start_index, end_index); |
| |
| pagevec_init(&pvec, 0); |
| 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(bdev, mapping, indices[i], |
| pvec.pages[i]); |
| if (ret < 0) |
| return ret; |
| } |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); |
| |
| static int dax_insert_mapping(struct address_space *mapping, |
| struct block_device *bdev, sector_t sector, size_t size, |
| void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf) |
| { |
| unsigned long vaddr = (unsigned long)vmf->virtual_address; |
| struct blk_dax_ctl dax = { |
| .sector = sector, |
| .size = size, |
| }; |
| void *ret; |
| void *entry = *entryp; |
| |
| if (dax_map_atomic(bdev, &dax) < 0) |
| return PTR_ERR(dax.addr); |
| dax_unmap_atomic(bdev, &dax); |
| |
| ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0); |
| if (IS_ERR(ret)) |
| return PTR_ERR(ret); |
| *entryp = ret; |
| |
| return vm_insert_mixed(vma, vaddr, dax.pfn); |
| } |
| |
| /** |
| * dax_pfn_mkwrite - handle first write to DAX page |
| * @vma: The virtual memory area where the fault occurred |
| * @vmf: The description of the fault |
| */ |
| int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) |
| { |
| struct file *file = vma->vm_file; |
| struct address_space *mapping = file->f_mapping; |
| void *entry; |
| pgoff_t index = vmf->pgoff; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| entry = get_unlocked_mapping_entry(mapping, index, NULL); |
| if (!entry || !radix_tree_exceptional_entry(entry)) |
| goto out; |
| radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY); |
| put_unlocked_mapping_entry(mapping, index, entry); |
| out: |
| spin_unlock_irq(&mapping->tree_lock); |
| return VM_FAULT_NOPAGE; |
| } |
| EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); |
| |
| 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, sector_t sector, |
| unsigned int offset, unsigned int length) |
| { |
| struct blk_dax_ctl dax = { |
| .sector = sector, |
| .size = PAGE_SIZE, |
| }; |
| |
| if (dax_range_is_aligned(bdev, offset, length)) { |
| sector_t start_sector = dax.sector + (offset >> 9); |
| |
| return blkdev_issue_zeroout(bdev, start_sector, |
| length >> 9, GFP_NOFS, true); |
| } else { |
| if (dax_map_atomic(bdev, &dax) < 0) |
| return PTR_ERR(dax.addr); |
| clear_pmem(dax.addr + offset, length); |
| dax_unmap_atomic(bdev, &dax); |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(__dax_zero_page_range); |
| |
| #ifdef CONFIG_FS_IOMAP |
| static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) |
| { |
| return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9); |
| } |
| |
| static loff_t |
| dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, |
| struct iomap *iomap) |
| { |
| struct iov_iter *iter = data; |
| loff_t end = pos + length, done = 0; |
| ssize_t ret = 0; |
| |
| 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; |
| |
| while (pos < end) { |
| unsigned offset = pos & (PAGE_SIZE - 1); |
| struct blk_dax_ctl dax = { 0 }; |
| ssize_t map_len; |
| |
| dax.sector = dax_iomap_sector(iomap, pos); |
| dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK; |
| map_len = dax_map_atomic(iomap->bdev, &dax); |
| if (map_len < 0) { |
| ret = map_len; |
| break; |
| } |
| |
| dax.addr += offset; |
| map_len -= offset; |
| if (map_len > end - pos) |
| map_len = end - pos; |
| |
| if (iov_iter_rw(iter) == WRITE) |
| map_len = copy_from_iter_pmem(dax.addr, map_len, iter); |
| else |
| map_len = copy_to_iter(dax.addr, map_len, iter); |
| dax_unmap_atomic(iomap->bdev, &dax); |
| if (map_len <= 0) { |
| ret = map_len ? map_len : -EFAULT; |
| break; |
| } |
| |
| pos += map_len; |
| length -= map_len; |
| done += map_len; |
| } |
| |
| 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, |
| 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) |
| flags |= IOMAP_WRITE; |
| |
| /* |
| * Yes, even DAX files can have page cache attached to them: A zeroed |
| * page is inserted into the pagecache when we have to serve a write |
| * fault on a hole. It should never be dirtied and can simply be |
| * dropped from the pagecache once we get real data for the page. |
| * |
| * XXX: This is racy against mmap, and there's nothing we can do about |
| * it. We'll eventually need to shift this down even further so that |
| * we can check if we allocated blocks over a hole first. |
| */ |
| if (mapping->nrpages) { |
| ret = invalidate_inode_pages2_range(mapping, |
| pos >> PAGE_SHIFT, |
| (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT); |
| WARN_ON_ONCE(ret); |
| } |
| |
| 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); |
| |
| /** |
| * dax_iomap_fault - handle a page fault on a DAX file |
| * @vma: The virtual memory area where the fault occurred |
| * @vmf: The description of the fault |
| * @ops: iomap ops passed from the file system |
| * |
| * When a page fault occurs, filesystems may call this helper in their fault |
| * or mkwrite handler for DAX files. Assumes the caller has done all the |
| * necessary locking for the page fault to proceed successfully. |
| */ |
| int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, |
| struct iomap_ops *ops) |
| { |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| struct inode *inode = mapping->host; |
| unsigned long vaddr = (unsigned long)vmf->virtual_address; |
| loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; |
| sector_t sector; |
| struct iomap iomap = { 0 }; |
| unsigned flags = IOMAP_FAULT; |
| int error, major = 0; |
| int locked_status = 0; |
| void *entry; |
| |
| /* |
| * 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)) |
| return VM_FAULT_SIGBUS; |
| |
| entry = grab_mapping_entry(mapping, vmf->pgoff, 0); |
| if (IS_ERR(entry)) { |
| error = PTR_ERR(entry); |
| goto out; |
| } |
| |
| if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) |
| flags |= IOMAP_WRITE; |
| |
| /* |
| * 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 (error) |
| goto unlock_entry; |
| if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { |
| error = -EIO; /* fs corruption? */ |
| goto finish_iomap; |
| } |
| |
| sector = dax_iomap_sector(&iomap, pos); |
| |
| if (vmf->cow_page) { |
| 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, sector, PAGE_SIZE, |
| vmf->cow_page, vaddr); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| error = -EIO; |
| break; |
| } |
| |
| if (error) |
| goto finish_iomap; |
| if (!radix_tree_exceptional_entry(entry)) { |
| vmf->page = entry; |
| locked_status = VM_FAULT_LOCKED; |
| } else { |
| vmf->entry = entry; |
| locked_status = VM_FAULT_DAX_LOCKED; |
| } |
| goto finish_iomap; |
| } |
| |
| switch (iomap.type) { |
| case IOMAP_MAPPED: |
| if (iomap.flags & IOMAP_F_NEW) { |
| count_vm_event(PGMAJFAULT); |
| mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
| major = VM_FAULT_MAJOR; |
| } |
| error = dax_insert_mapping(mapping, iomap.bdev, sector, |
| PAGE_SIZE, &entry, vma, vmf); |
| break; |
| case IOMAP_UNWRITTEN: |
| case IOMAP_HOLE: |
| if (!(vmf->flags & FAULT_FLAG_WRITE)) { |
| locked_status = dax_load_hole(mapping, entry, vmf); |
| break; |
| } |
| /*FALLTHRU*/ |
| default: |
| WARN_ON_ONCE(1); |
| error = -EIO; |
| break; |
| } |
| |
| finish_iomap: |
| if (ops->iomap_end) { |
| if (error) { |
| /* keep previous error */ |
| ops->iomap_end(inode, pos, PAGE_SIZE, 0, flags, |
| &iomap); |
| } else { |
| error = ops->iomap_end(inode, pos, PAGE_SIZE, |
| PAGE_SIZE, flags, &iomap); |
| } |
| } |
| unlock_entry: |
| if (!locked_status || error) |
| put_locked_mapping_entry(mapping, vmf->pgoff, entry); |
| out: |
| if (error == -ENOMEM) |
| return VM_FAULT_OOM | major; |
| /* -EBUSY is fine, somebody else faulted on the same PTE */ |
| if (error < 0 && error != -EBUSY) |
| return VM_FAULT_SIGBUS | major; |
| if (locked_status) { |
| WARN_ON_ONCE(error); /* -EBUSY from ops->iomap_end? */ |
| return locked_status; |
| } |
| return VM_FAULT_NOPAGE | major; |
| } |
| EXPORT_SYMBOL_GPL(dax_iomap_fault); |
| |
| #ifdef CONFIG_FS_DAX_PMD |
| /* |
| * The 'colour' (ie low bits) within a PMD of a page offset. This comes up |
| * more often than one might expect in the below functions. |
| */ |
| #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) |
| |
| static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd, |
| struct vm_fault *vmf, unsigned long address, |
| struct iomap *iomap, loff_t pos, bool write, void **entryp) |
| { |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| struct block_device *bdev = iomap->bdev; |
| struct blk_dax_ctl dax = { |
| .sector = dax_iomap_sector(iomap, pos), |
| .size = PMD_SIZE, |
| }; |
| long length = dax_map_atomic(bdev, &dax); |
| void *ret; |
| |
| if (length < 0) /* dax_map_atomic() failed */ |
| return VM_FAULT_FALLBACK; |
| if (length < PMD_SIZE) |
| goto unmap_fallback; |
| if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) |
| goto unmap_fallback; |
| if (!pfn_t_devmap(dax.pfn)) |
| goto unmap_fallback; |
| |
| dax_unmap_atomic(bdev, &dax); |
| |
| ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector, |
| RADIX_DAX_PMD); |
| if (IS_ERR(ret)) |
| return VM_FAULT_FALLBACK; |
| *entryp = ret; |
| |
| return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write); |
| |
| unmap_fallback: |
| dax_unmap_atomic(bdev, &dax); |
| return VM_FAULT_FALLBACK; |
| } |
| |
| static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd, |
| struct vm_fault *vmf, unsigned long address, |
| struct iomap *iomap, void **entryp) |
| { |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| unsigned long pmd_addr = address & PMD_MASK; |
| struct page *zero_page; |
| spinlock_t *ptl; |
| pmd_t pmd_entry; |
| void *ret; |
| |
| zero_page = mm_get_huge_zero_page(vma->vm_mm); |
| |
| if (unlikely(!zero_page)) |
| return VM_FAULT_FALLBACK; |
| |
| ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0, |
| RADIX_DAX_PMD | RADIX_DAX_HZP); |
| if (IS_ERR(ret)) |
| return VM_FAULT_FALLBACK; |
| *entryp = ret; |
| |
| ptl = pmd_lock(vma->vm_mm, pmd); |
| if (!pmd_none(*pmd)) { |
| spin_unlock(ptl); |
| return VM_FAULT_FALLBACK; |
| } |
| |
| pmd_entry = mk_pmd(zero_page, vma->vm_page_prot); |
| pmd_entry = pmd_mkhuge(pmd_entry); |
| set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry); |
| spin_unlock(ptl); |
| return VM_FAULT_NOPAGE; |
| } |
| |
| int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, |
| pmd_t *pmd, unsigned int flags, struct iomap_ops *ops) |
| { |
| struct address_space *mapping = vma->vm_file->f_mapping; |
| unsigned long pmd_addr = address & PMD_MASK; |
| bool write = flags & FAULT_FLAG_WRITE; |
| unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; |
| struct inode *inode = mapping->host; |
| int result = VM_FAULT_FALLBACK; |
| struct iomap iomap = { 0 }; |
| pgoff_t max_pgoff, pgoff; |
| struct vm_fault vmf; |
| void *entry; |
| loff_t pos; |
| int error; |
| |
| /* 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; |
| |
| /* |
| * 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 = (i_size_read(inode) - 1) >> PAGE_SHIFT; |
| |
| if (pgoff > max_pgoff) |
| return VM_FAULT_SIGBUS; |
| |
| /* 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 2M empty entry, a DAX |
| * PMD or a HZP entry. 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; |
| |
| /* |
| * 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; |
| |
| vmf.pgoff = pgoff; |
| vmf.flags = flags; |
| vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO; |
| |
| switch (iomap.type) { |
| case IOMAP_MAPPED: |
| result = dax_pmd_insert_mapping(vma, pmd, &vmf, address, |
| &iomap, pos, write, &entry); |
| break; |
| case IOMAP_UNWRITTEN: |
| case IOMAP_HOLE: |
| if (WARN_ON_ONCE(write)) |
| goto finish_iomap; |
| result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap, |
| &entry); |
| break; |
| default: |
| WARN_ON_ONCE(1); |
| break; |
| } |
| |
| finish_iomap: |
| if (ops->iomap_end) { |
| if (result == VM_FAULT_FALLBACK) { |
| ops->iomap_end(inode, pos, PMD_SIZE, 0, iomap_flags, |
| &iomap); |
| } else { |
| error = ops->iomap_end(inode, pos, PMD_SIZE, PMD_SIZE, |
| iomap_flags, &iomap); |
| if (error) |
| result = VM_FAULT_FALLBACK; |
| } |
| } |
| unlock_entry: |
| put_locked_mapping_entry(mapping, pgoff, entry); |
| fallback: |
| if (result == VM_FAULT_FALLBACK) { |
| split_huge_pmd(vma, pmd, address); |
| count_vm_event(THP_FAULT_FALLBACK); |
| } |
| return result; |
| } |
| EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault); |
| #endif /* CONFIG_FS_DAX_PMD */ |
| #endif /* CONFIG_FS_IOMAP */ |