diff options
Diffstat (limited to 'fs/dax.c')
| -rw-r--r-- | fs/dax.c | 1489 |
1 files changed, 726 insertions, 763 deletions
@@ -31,28 +31,15 @@ #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" -/* - * We use lowest available bit in exceptional entry for locking, other two - * bits to determine entry type. In total 3 special bits. - */ -#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3) -#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) -#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) -#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD) -#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK) -#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) -#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ - RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \ - RADIX_TREE_EXCEPTIONAL_ENTRY)) - /* 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) -wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; +static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; static int __init init_dax_wait_table(void) { @@ -64,14 +51,6 @@ static int __init init_dax_wait_table(void) } fs_initcall(init_dax_wait_table); -static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping, - pgoff_t index) -{ - unsigned long hash = hash_long((unsigned long)mapping ^ index, - DAX_WAIT_TABLE_BITS); - return wait_table + hash; -} - static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax) { struct request_queue *q = bdev->bd_queue; @@ -98,209 +77,52 @@ static void dax_unmap_atomic(struct block_device *bdev, blk_queue_exit(bdev->bd_queue); } -struct page *read_dax_sector(struct block_device *bdev, sector_t n) +static int dax_is_pmd_entry(void *entry) { - 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; + return (unsigned long)entry & RADIX_DAX_PMD; } -static bool buffer_written(struct buffer_head *bh) +static int dax_is_pte_entry(void *entry) { - return buffer_mapped(bh) && !buffer_unwritten(bh); + return !((unsigned long)entry & RADIX_DAX_PMD); } -/* - * When ext4 encounters a hole, it returns without modifying the buffer_head - * which means that we can't trust b_size. To cope with this, we set b_state - * to 0 before calling get_block and, if any bit is set, we know we can trust - * b_size. Unfortunate, really, since ext4 knows precisely how long a hole is - * and would save us time calling get_block repeatedly. - */ -static bool buffer_size_valid(struct buffer_head *bh) +static int dax_is_zero_entry(void *entry) { - return bh->b_state != 0; + return (unsigned long)entry & RADIX_DAX_HZP; } - -static sector_t to_sector(const struct buffer_head *bh, - const struct inode *inode) +static int dax_is_empty_entry(void *entry) { - sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); - - return sector; + return (unsigned long)entry & RADIX_DAX_EMPTY; } -static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, - loff_t start, loff_t end, get_block_t get_block, - struct buffer_head *bh) +struct page *read_dax_sector(struct block_device *bdev, sector_t n) { - loff_t pos = start, max = start, bh_max = start; - bool hole = false; - struct block_device *bdev = NULL; - int rw = iov_iter_rw(iter), rc; - long map_len = 0; + struct page *page = alloc_pages(GFP_KERNEL, 0); struct blk_dax_ctl dax = { - .addr = ERR_PTR(-EIO), + .size = PAGE_SIZE, + .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), }; - unsigned blkbits = inode->i_blkbits; - sector_t file_blks = (i_size_read(inode) + (1 << blkbits) - 1) - >> blkbits; - - if (rw == READ) - end = min(end, i_size_read(inode)); - - while (pos < end) { - size_t len; - if (pos == max) { - long page = pos >> PAGE_SHIFT; - sector_t block = page << (PAGE_SHIFT - blkbits); - unsigned first = pos - (block << blkbits); - long size; - - if (pos == bh_max) { - bh->b_size = PAGE_ALIGN(end - pos); - bh->b_state = 0; - rc = get_block(inode, block, bh, rw == WRITE); - if (rc) - break; - if (!buffer_size_valid(bh)) - bh->b_size = 1 << blkbits; - bh_max = pos - first + bh->b_size; - bdev = bh->b_bdev; - /* - * We allow uninitialized buffers for writes - * beyond EOF as those cannot race with faults - */ - WARN_ON_ONCE( - (buffer_new(bh) && block < file_blks) || - (rw == WRITE && buffer_unwritten(bh))); - } else { - unsigned done = bh->b_size - - (bh_max - (pos - first)); - bh->b_blocknr += done >> blkbits; - bh->b_size -= done; - } - - hole = rw == READ && !buffer_written(bh); - if (hole) { - size = bh->b_size - first; - } else { - dax_unmap_atomic(bdev, &dax); - dax.sector = to_sector(bh, inode); - dax.size = bh->b_size; - map_len = dax_map_atomic(bdev, &dax); - if (map_len < 0) { - rc = map_len; - break; - } - dax.addr += first; - size = map_len - first; - } - /* - * pos + size is one past the last offset for IO, - * so pos + size can overflow loff_t at extreme offsets. - * Cast to u64 to catch this and get the true minimum. - */ - max = min_t(u64, pos + size, end); - } - - if (iov_iter_rw(iter) == WRITE) { - len = copy_from_iter_pmem(dax.addr, max - pos, iter); - } else if (!hole) - len = copy_to_iter((void __force *) dax.addr, max - pos, - iter); - else - len = iov_iter_zero(max - pos, iter); - - if (!len) { - rc = -EFAULT; - break; - } + long rc; - pos += len; - if (!IS_ERR(dax.addr)) - dax.addr += len; - } + 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 (pos == start) ? rc : pos - start; -} - -/** - * dax_do_io - Perform I/O to a DAX file - * @iocb: The control block for this I/O - * @inode: The file which the I/O is directed at - * @iter: The addresses to do I/O from or to - * @get_block: The filesystem method used to translate file offsets to blocks - * @end_io: A filesystem callback for I/O completion - * @flags: See below - * - * This function uses the same locking scheme as do_blockdev_direct_IO: - * If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the - * caller for writes. For reads, we take and release the i_mutex ourselves. - * If DIO_LOCKING is not set, the filesystem takes care of its own locking. - * As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O - * is in progress. - */ -ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, - struct iov_iter *iter, get_block_t get_block, - dio_iodone_t end_io, int flags) -{ - struct buffer_head bh; - ssize_t retval = -EINVAL; - loff_t pos = iocb->ki_pos; - loff_t end = pos + iov_iter_count(iter); - - memset(&bh, 0, sizeof(bh)); - bh.b_bdev = inode->i_sb->s_bdev; - - if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) - inode_lock(inode); - - /* Protects against truncate */ - if (!(flags & DIO_SKIP_DIO_COUNT)) - inode_dio_begin(inode); - - retval = dax_io(inode, iter, pos, end, get_block, &bh); - - if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) - inode_unlock(inode); - - if (end_io) { - int err; - - err = end_io(iocb, pos, retval, bh.b_private); - if (err) - retval = err; - } - - if (!(flags & DIO_SKIP_DIO_COUNT)) - inode_dio_end(inode); - return retval; + return page; } -EXPORT_SYMBOL_GPL(dax_do_io); /* * DAX radix tree locking */ struct exceptional_entry_key { struct address_space *mapping; - unsigned long index; + pgoff_t entry_start; }; struct wait_exceptional_entry_queue { @@ -308,6 +130,26 @@ struct wait_exceptional_entry_queue { 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) { @@ -316,7 +158,7 @@ static int wake_exceptional_entry_func(wait_queue_t *wait, unsigned int mode, container_of(wait, struct wait_exceptional_entry_queue, wait); if (key->mapping != ewait->key.mapping || - key->index != ewait->key.index) + key->entry_start != ewait->key.entry_start) return 0; return autoremove_wake_function(wait, mode, sync, NULL); } @@ -342,7 +184,7 @@ static inline void *lock_slot(struct address_space *mapping, void **slot) radix_tree_deref_slot_protected(slot, &mapping->tree_lock); entry |= RADIX_DAX_ENTRY_LOCK; - radix_tree_replace_slot(slot, (void *)entry); + radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); return (void *)entry; } @@ -356,7 +198,7 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot) radix_tree_deref_slot_protected(slot, &mapping->tree_lock); entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK; - radix_tree_replace_slot(slot, (void *)entry); + radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry); return (void *)entry; } @@ -372,24 +214,24 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot) static void *get_unlocked_mapping_entry(struct address_space *mapping, pgoff_t index, void ***slotp) { - void *ret, **slot; + void *entry, **slot; struct wait_exceptional_entry_queue ewait; - wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index); + wait_queue_head_t *wq; init_wait(&ewait.wait); ewait.wait.func = wake_exceptional_entry_func; - ewait.key.mapping = mapping; - ewait.key.index = index; for (;;) { - ret = __radix_tree_lookup(&mapping->page_tree, index, NULL, + entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); - if (!ret || !radix_tree_exceptional_entry(ret) || + if (!entry || !radix_tree_exceptional_entry(entry) || !slot_locked(mapping, slot)) { if (slotp) *slotp = slot; - return ret; + 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); @@ -399,52 +241,173 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping, } } +static 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); +} + +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) +static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, + unsigned long size_flag) { - void *ret, **slot; + bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */ + void *entry, **slot; restart: spin_lock_irq(&mapping->tree_lock); - ret = get_unlocked_mapping_entry(mapping, index, &slot); + 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 (!ret) { + 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 (err) { + if (pmd_downgrade) + put_locked_mapping_entry(mapping, index, entry); return ERR_PTR(err); - ret = (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | - RADIX_DAX_ENTRY_LOCK); + } spin_lock_irq(&mapping->tree_lock); - err = radix_tree_insert(&mapping->page_tree, index, ret); + + 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? */ - if (err == -EEXIST) + /* + * 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 ret; + return entry; } /* Normal page in radix tree? */ - if (!radix_tree_exceptional_entry(ret)) { - struct page *page = ret; + if (!radix_tree_exceptional_entry(entry)) { + struct page *page = entry; get_page(page); spin_unlock_irq(&mapping->tree_lock); @@ -457,15 +420,26 @@ restart: } return page; } - ret = lock_slot(mapping, slot); + entry = lock_slot(mapping, slot); + out_unlock: spin_unlock_irq(&mapping->tree_lock); - return ret; + 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, bool wake_all) + pgoff_t index, void *entry, bool wake_all) { - wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index); + 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 @@ -473,66 +447,41 @@ void dax_wake_mapping_entry_waiter(struct address_space *mapping, * 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)) { - struct exceptional_entry_key key; - - key.mapping = mapping; - key.index = index; + 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) +static int __dax_invalidate_mapping_entry(struct address_space *mapping, + pgoff_t index, bool trunc) { - void *ret, **slot; + int ret = 0; + void *entry; + struct radix_tree_root *page_tree = &mapping->page_tree; spin_lock_irq(&mapping->tree_lock); - ret = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot); - if (WARN_ON_ONCE(!ret || !radix_tree_exceptional_entry(ret) || - !slot_locked(mapping, slot))) { - spin_unlock_irq(&mapping->tree_lock); - return; - } - unlock_slot(mapping, slot); + entry = get_unlocked_mapping_entry(mapping, index, NULL); + if (!entry || !radix_tree_exceptional_entry(entry)) + goto out; + if (!trunc && + (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || + radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))) + goto out; + radix_tree_delete(page_tree, index); + mapping->nrexceptional--; + ret = 1; +out: + put_unlocked_mapping_entry(mapping, index, entry); spin_unlock_irq(&mapping->tree_lock); - dax_wake_mapping_entry_waiter(mapping, index, false); -} - -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, false); + 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) { - void *entry; + int ret = __dax_invalidate_mapping_entry(mapping, index, true); - 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 @@ -540,16 +489,46 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) * 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); + WARN_ON_ONCE(!ret); + return ret; +} + +/* + * Invalidate exceptional DAX entry if easily possible. This handles DAX + * entries for invalidate_inode_pages() so we evict the entry only if we can + * do so without blocking. + */ +int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index) +{ + int ret = 0; + void *entry, **slot; + struct radix_tree_root *page_tree = &mapping->page_tree; + + spin_lock_irq(&mapping->tree_lock); + entry = __radix_tree_lookup(page_tree, index, NULL, &slot); + if (!entry || !radix_tree_exceptional_entry(entry) || + slot_locked(mapping, slot)) + goto out; + if (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || + radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) + goto out; + radix_tree_delete(page_tree, index); mapping->nrexceptional--; + ret = 1; +out: spin_unlock_irq(&mapping->tree_lock); - dax_wake_mapping_entry_waiter(mapping, index, true); + if (ret) + dax_wake_mapping_entry_waiter(mapping, index, entry, true); + return ret; +} - return 1; +/* + * 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); } /* @@ -560,26 +539,34 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) * 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, +static int dax_load_hole(struct address_space *mapping, void **entry, struct vm_fault *vmf) { struct page *page; + int ret; /* Hole page already exists? Return it... */ - if (!radix_tree_exceptional_entry(entry)) { - vmf->page = entry; - return VM_FAULT_LOCKED; + if (!radix_tree_exceptional_entry(*entry)) { + page = *entry; + goto out; } /* 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); + if (!page) return VM_FAULT_OOM; - } + out: vmf->page = page; - return VM_FAULT_LOCKED; + ret = finish_fault(vmf); + vmf->page = NULL; + *entry = page; + if (!ret) { + /* Grab reference for PTE that is now referencing the page */ + get_page(page); + return VM_FAULT_NOPAGE; + } + return ret; } static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size, @@ -600,11 +587,17 @@ static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size return 0; } -#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_SHIFT)) - +/* + * 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) + void *entry, sector_t sector, + unsigned long flags) { struct radix_tree_root *page_tree = &mapping->page_tree; int error = 0; @@ -627,28 +620,43 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, 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 = (void *)((unsigned long)RADIX_DAX_ENTRY(sector, false) | - RADIX_DAX_ENTRY_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, new_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 { + } 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, NULL, &slot); + ret = __radix_tree_lookup(page_tree, index, &node, &slot); WARN_ON_ONCE(ret != entry); - radix_tree_replace_slot(slot, new_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); @@ -668,63 +676,171 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, return new_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; + bool changed; + + i_mmap_lock_read(mapping); + vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { + unsigned long address; + + cond_resched(); + + if (!(vma->vm_flags & VM_SHARED)) + continue; + + address = pgoff_address(index, vma); + changed = false; + if (follow_pte_pmd(vma->vm_mm, address, &ptep, &pmdp, &ptl)) + continue; + + 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); + changed = true; +unlock_pmd: + spin_unlock(ptl); +#endif + } 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); + changed = true; +unlock_pte: + pte_unmap_unlock(ptep, ptl); + } + + if (changed) + mmu_notifier_invalidate_page(vma->vm_mm, address); + } + i_mmap_unlock_read(mapping); +} + 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; - int type = RADIX_DAX_TYPE(entry); - struct radix_tree_node *node; struct blk_dax_ctl dax; - void **slot; + void *entry2, **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. + * A page got tagged dirty in DAX mapping? Something is seriously + * wrong. */ - 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(!radix_tree_exceptional_entry(entry))) + return -EIO; - if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { + spin_lock_irq(&mapping->tree_lock); + entry2 = get_unlocked_mapping_entry(mapping, index, &slot); + /* Entry got punched out / reallocated? */ + if (!entry2 || !radix_tree_exceptional_entry(entry2)) + goto put_unlocked; + /* + * Entry got reallocated elsewhere? No need to writeback. We have to + * compare sectors as we must not bail out due to difference in lockbit + * or entry type. + */ + if (dax_radix_sector(entry2) != dax_radix_sector(entry)) + goto put_unlocked; + if (WARN_ON_ONCE(dax_is_empty_entry(entry) || + dax_is_zero_entry(entry))) { ret = -EIO; - goto unlock; + goto put_unlocked; } - dax.sector = RADIX_DAX_SECTOR(entry); - dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE); + /* Another fsync thread may have already written back this entry */ + if (!radix_tree_tag_get(page_tree, 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 tree_lock and once they do that they will + * see the entry locked and wait for it to unlock. + */ + radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); spin_unlock_irq(&mapping->tree_lock); /* + * 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); + + /* * 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) + if (ret < 0) { + put_locked_mapping_entry(mapping, index, entry); return ret; + } if (WARN_ON_ONCE(ret < dax.size)) { ret = -EIO; goto unmap; } + dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn)); wb_cache_pmem(dax.addr, dax.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. + */ spin_lock_irq(&mapping->tree_lock); - radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); + radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY); spin_unlock_irq(&mapping->tree_lock); unmap: dax_unmap_atomic(bdev, &dax); + put_locked_mapping_entry(mapping, index, entry); return ret; - unlock: + put_unlocked: + put_unlocked_mapping_entry(mapping, index, entry2); spin_unlock_irq(&mapping->tree_lock); return ret; } @@ -738,12 +854,11 @@ 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, pmd_index; + pgoff_t start_index, end_index; pgoff_t indices[PAGEVEC_SIZE]; struct pagevec pvec; bool done = false; int i, ret = 0; - void *entry; if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) return -EIO; @@ -753,15 +868,6 @@ int dax_writeback_mapping_range(struct address_space *mapping, start_index = wbc->range_start >> PAGE_SHIFT; end_index = wbc->range_end >> PAGE_SHIFT; - pmd_index = DAX_PMD_INDEX(start_index); - - rcu_read_lock(); - entry = radix_tree_lookup(&mapping->page_tree, pmd_index); - rcu_read_unlock(); - - /* see if the start of our range is covered by a PMD entry */ - if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) - start_index = pmd_index; tag_pages_for_writeback(mapping, start_index, end_index); @@ -794,7 +900,7 @@ 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; + unsigned long vaddr = vmf->address; struct blk_dax_ctl dax = { .sector = sector, .size = size, @@ -806,7 +912,7 @@ static int dax_insert_mapping(struct address_space *mapping, return PTR_ERR(dax.addr); dax_unmap_atomic(bdev, &dax); - ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector); + ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0); if (IS_ERR(ret)) return PTR_ERR(ret); *entryp = ret; @@ -815,323 +921,6 @@ static int dax_insert_mapping(struct address_space *mapping, } /** - * dax_fault - handle a page fault on a DAX file - * @vma: The virtual memory area where the fault occurred - * @vmf: The description of the fault - * @get_block: The filesystem method used to translate file offsets to blocks - * - * When a page fault occurs, filesystems may call this helper in their - * fault handler for DAX files. dax_fault() assumes the caller has done all - * the necessary locking for the page fault to proceed successfully. - */ -int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, - get_block_t get_block) -{ - struct file *file = vma->vm_file; - struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - void *entry; - struct buffer_head bh; - unsigned long vaddr = (unsigned long)vmf->virtual_address; - unsigned blkbits = inode->i_blkbits; - sector_t block; - pgoff_t size; - int error; - int major = 0; - - /* - * 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. - */ - size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (vmf->pgoff >= size) - return VM_FAULT_SIGBUS; - - memset(&bh, 0, sizeof(bh)); - block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits); - bh.b_bdev = inode->i_sb->s_bdev; - bh.b_size = PAGE_SIZE; - - entry = grab_mapping_entry(mapping, vmf->pgoff); - if (IS_ERR(entry)) { - error = PTR_ERR(entry); - goto out; - } - - error = get_block(inode, block, &bh, 0); - if (!error && (bh.b_size < PAGE_SIZE)) - error = -EIO; /* fs corruption? */ - if (error) - goto unlock_entry; - - if (vmf->cow_page) { - struct page *new_page = vmf->cow_page; - if (buffer_written(&bh)) - error = copy_user_dax(bh.b_bdev, to_sector(&bh, inode), - bh.b_size, new_page, vaddr); - else - clear_user_highpage(new_page, vaddr); - if (error) - goto unlock_entry; - if (!radix_tree_exceptional_entry(entry)) { - vmf->page = entry; - return VM_FAULT_LOCKED; - } - vmf->entry = entry; - return VM_FAULT_DAX_LOCKED; - } - - if (!buffer_mapped(&bh)) { - if (vmf->flags & FAULT_FLAG_WRITE) { - error = get_block(inode, block, &bh, 1); - count_vm_event(PGMAJFAULT); - mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); - major = VM_FAULT_MAJOR; - if (!error && (bh.b_size < PAGE_SIZE)) - error = -EIO; - if (error) - goto unlock_entry; - } else { - return dax_load_hole(mapping, entry, vmf); - } - } - - /* Filesystem should not return unwritten buffers to us! */ - WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); - error = dax_insert_mapping(mapping, bh.b_bdev, to_sector(&bh, inode), - bh.b_size, &entry, vma, vmf); - unlock_entry: - 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; - return VM_FAULT_NOPAGE | major; -} -EXPORT_SYMBOL_GPL(dax_fault); - -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) -/* - * The 'colour' (ie low bits) within a PMD of a page offset. This comes up - * more often than one might expect in the below function. - */ -#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) - -static void __dax_dbg(struct buffer_head *bh, unsigned long address, - const char *reason, const char *fn) -{ - if (bh) { - char bname[BDEVNAME_SIZE]; - bdevname(bh->b_bdev, bname); - pr_debug("%s: %s addr: %lx dev %s state %lx start %lld " - "length %zd fallback: %s\n", fn, current->comm, - address, bname, bh->b_state, (u64)bh->b_blocknr, - bh->b_size, reason); - } else { - pr_debug("%s: %s addr: %lx fallback: %s\n", fn, - current->comm, address, reason); - } -} - -#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd") - -/** - * dax_pmd_fault - handle a PMD fault on a DAX file - * @vma: The virtual memory area where the fault occurred - * @vmf: The description of the fault - * @get_block: The filesystem method used to translate file offsets to blocks - * - * When a page fault occurs, filesystems may call this helper in their - * pmd_fault handler for DAX files. - */ -int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, - pmd_t *pmd, unsigned int flags, get_block_t get_block) -{ - struct file *file = vma->vm_file; - struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - struct buffer_head bh; - unsigned blkbits = inode->i_blkbits; - unsigned long pmd_addr = address & PMD_MASK; - bool write = flags & FAULT_FLAG_WRITE; - struct block_device *bdev; - pgoff_t size, pgoff; - sector_t block; - int result = 0; - bool alloc = false; - - /* dax pmd mappings require pfn_t_devmap() */ - if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) - return VM_FAULT_FALLBACK; - - /* Fall back to PTEs if we're going to COW */ - if (write && !(vma->vm_flags & VM_SHARED)) { - split_huge_pmd(vma, pmd, address); - dax_pmd_dbg(NULL, address, "cow write"); - return VM_FAULT_FALLBACK; - } - /* If the PMD would extend outside the VMA */ - if (pmd_addr < vma->vm_start) { - dax_pmd_dbg(NULL, address, "vma start unaligned"); - return VM_FAULT_FALLBACK; - } - if ((pmd_addr + PMD_SIZE) > vma->vm_end) { - dax_pmd_dbg(NULL, address, "vma end unaligned"); - return VM_FAULT_FALLBACK; - } - - pgoff = linear_page_index(vma, pmd_addr); - size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (pgoff >= size) - return VM_FAULT_SIGBUS; - /* If the PMD would cover blocks out of the file */ - if ((pgoff | PG_PMD_COLOUR) >= size) { - dax_pmd_dbg(NULL, address, - "offset + huge page size > file size"); - return VM_FAULT_FALLBACK; - } - - memset(&bh, 0, sizeof(bh)); - bh.b_bdev = inode->i_sb->s_bdev; - block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); - - bh.b_size = PMD_SIZE; - - if (get_block(inode, block, &bh, 0) != 0) - return VM_FAULT_SIGBUS; - - if (!buffer_mapped(&bh) && write) { - if (get_block(inode, block, &bh, 1) != 0) - return VM_FAULT_SIGBUS; - alloc = true; - WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); - } - - bdev = bh.b_bdev; - - /* - * If the filesystem isn't willing to tell us the length of a hole, - * just fall back to PTEs. Calling get_block 512 times in a loop - * would be silly. - */ - if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) { - dax_pmd_dbg(&bh, address, "allocated block too small"); - return VM_FAULT_FALLBACK; - } - - /* - * If we allocated new storage, make sure no process has any - * zero pages covering this hole - */ - if (alloc) { - loff_t lstart = pgoff << PAGE_SHIFT; - loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */ - - truncate_pagecache_range(inode, lstart, lend); - } - - if (!write && !buffer_mapped(&bh)) { - spinlock_t *ptl; - pmd_t entry; - struct page *zero_page = mm_get_huge_zero_page(vma->vm_mm); - - if (unlikely(!zero_page)) { - dax_pmd_dbg(&bh, address, "no zero page"); - goto fallback; - } - - ptl = pmd_lock(vma->vm_mm, pmd); - if (!pmd_none(*pmd)) { - spin_unlock(ptl); - dax_pmd_dbg(&bh, address, "pmd already present"); - goto fallback; - } - - dev_dbg(part_to_dev(bdev->bd_part), - "%s: %s addr: %lx pfn: <zero> sect: %llx\n", - __func__, current->comm, address, - (unsigned long long) to_sector(&bh, inode)); - - entry = mk_pmd(zero_page, vma->vm_page_prot); - entry = pmd_mkhuge(entry); - set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); - result = VM_FAULT_NOPAGE; - spin_unlock(ptl); - } else { - struct blk_dax_ctl dax = { - .sector = to_sector(&bh, inode), - .size = PMD_SIZE, - }; - long length = dax_map_atomic(bdev, &dax); - - if (length < 0) { - dax_pmd_dbg(&bh, address, "dax-error fallback"); - goto fallback; - } - if (length < PMD_SIZE) { - dax_pmd_dbg(&bh, address, "dax-length too small"); - dax_unmap_atomic(bdev, &dax); - goto fallback; - } - if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) { - dax_pmd_dbg(&bh, address, "pfn unaligned"); - dax_unmap_atomic(bdev, &dax); - goto fallback; - } - - if (!pfn_t_devmap(dax.pfn)) { - dax_unmap_atomic(bdev, &dax); - dax_pmd_dbg(&bh, address, "pfn not in memmap"); - goto fallback; - } - dax_unmap_atomic(bdev, &dax); - - /* - * For PTE faults we insert a radix tree entry for reads, and - * leave it clean. Then on the first write we dirty the radix - * tree entry via the dax_pfn_mkwrite() path. This sequence - * allows the dax_pfn_mkwrite() call to be simpler and avoid a - * call into get_block() to translate the pgoff to a sector in - * order to be able to create a new radix tree entry. - * - * The PMD path doesn't have an equivalent to - * dax_pfn_mkwrite(), though, so for a read followed by a - * write we traverse all the way through dax_pmd_fault() - * twice. This means we can just skip inserting a radix tree - * entry completely on the initial read and just wait until - * the write to insert a dirty entry. - */ - if (write) { - /* - * We should insert radix-tree entry and dirty it here. - * For now this is broken... - */ - } - - dev_dbg(part_to_dev(bdev->bd_part), - "%s: %s addr: %lx pfn: %lx sect: %llx\n", - __func__, current->comm, address, - pfn_t_to_pfn(dax.pfn), - (unsigned long long) dax.sector); - result |= vmf_insert_pfn_pmd(vma, address, pmd, - dax.pfn, write); - } - - out: - return result; - - fallback: - count_vm_event(THP_FAULT_FALLBACK); - result = VM_FAULT_FALLBACK; - goto out; -} -EXPORT_SYMBOL_GPL(dax_pmd_fault); -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ - -/** * dax_pfn_mkwrite - handle first write to DAX page * @vma: The virtual memory area where the fault occurred * @vmf: The description of the fault @@ -1140,17 +929,27 @@ 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; + void *entry, **slot; 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; + entry = get_unlocked_mapping_entry(mapping, index, &slot); + if (!entry || !radix_tree_exceptional_entry(entry)) { + if (entry) + put_unlocked_mapping_entry(mapping, index, entry); + spin_unlock_irq(&mapping->tree_lock); + return VM_FAULT_NOPAGE; + } radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY); - put_unlocked_mapping_entry(mapping, index, entry); -out: + entry = lock_slot(mapping, slot); spin_unlock_irq(&mapping->tree_lock); + /* + * If we race with somebody updating the PTE and finish_mkwrite_fault() + * fails, we don't care. We need to return VM_FAULT_NOPAGE and retry + * the fault in either case. + */ + finish_mkwrite_fault(vmf); + put_locked_mapping_entry(mapping, index, entry); return VM_FAULT_NOPAGE; } EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); @@ -1191,62 +990,13 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector, } EXPORT_SYMBOL_GPL(__dax_zero_page_range); -/** - * dax_zero_page_range - zero a range within a page of a DAX file - * @inode: The file being truncated - * @from: The file offset that is being truncated to - * @length: The number of bytes to zero - * @get_block: The filesystem method used to translate file offsets to blocks - * - * This function can be called by a filesystem when it is zeroing part of a - * page in a DAX file. This is intended for hole-punch operations. If - * you are truncating a file, the helper function dax_truncate_page() may be - * more convenient. - */ -int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, - get_block_t get_block) +static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) { - struct buffer_head bh; - pgoff_t index = from >> PAGE_SHIFT; - unsigned offset = from & (PAGE_SIZE-1); - int err; - - /* Block boundary? Nothing to do */ - if (!length) - return 0; - BUG_ON((offset + length) > PAGE_SIZE); - - memset(&bh, 0, sizeof(bh)); - bh.b_bdev = inode->i_sb->s_bdev; - bh.b_size = PAGE_SIZE; - err = get_block(inode, index, &bh, 0); - if (err < 0 || !buffer_written(&bh)) - return err; - - return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode), - offset, length); + return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9); } -EXPORT_SYMBOL_GPL(dax_zero_page_range); -/** - * dax_truncate_page - handle a partial page being truncated in a DAX file - * @inode: The file being truncated - * @from: The file offset that is being truncated to - * @get_block: The filesystem method used to translate file offsets to blocks - * - * Similar to block_truncate_page(), this function can be called by a - * filesystem when it is truncating a DAX file to handle the partial page. - */ -int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) -{ - unsigned length = PAGE_ALIGN(from) - from; - return dax_zero_page_range(inode, from, length, get_block); -} -EXPORT_SYMBOL_GPL(dax_truncate_page); - -#ifdef CONFIG_FS_IOMAP static loff_t -iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, +dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct iov_iter *iter = data; @@ -1265,13 +1015,28 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, 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) && inode->i_mapping->nrpages) { + invalidate_inode_pages2_range(inode->i_mapping, + pos >> PAGE_SHIFT, + (end - 1) >> PAGE_SHIFT); + } + while (pos < end) { unsigned offset = pos & (PAGE_SIZE - 1); struct blk_dax_ctl dax = { 0 }; ssize_t map_len; - dax.sector = iomap->blkno + - (((pos & PAGE_MASK) - iomap->offset) >> 9); + if (fatal_signal_pending(current)) { + ret = -EINTR; + break; + } + + 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) { @@ -1303,7 +1068,7 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, } /** - * iomap_dax_rw - Perform I/O to a DAX file + * 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 @@ -1313,7 +1078,7 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, * and evicting any page cache pages in the region under I/O. */ ssize_t -iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, +dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops) { struct address_space *mapping = iocb->ki_filp->f_mapping; @@ -1324,26 +1089,9 @@ iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, 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, iomap_dax_actor); + iter, dax_iomap_actor); if (ret <= 0) break; pos += ret; @@ -1353,10 +1101,19 @@ iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, iocb->ki_pos += done; return done ? done : ret; } -EXPORT_SYMBOL_GPL(iomap_dax_rw); +EXPORT_SYMBOL_GPL(dax_iomap_rw); + +static int dax_fault_return(int error) +{ + if (error == 0) + return VM_FAULT_NOPAGE; + if (error == -ENOMEM) + return VM_FAULT_OOM; + return VM_FAULT_SIGBUS; +} /** - * iomap_dax_fault - handle a page fault on a DAX file + * 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 @@ -1365,17 +1122,18 @@ EXPORT_SYMBOL_GPL(iomap_dax_rw); * or mkwrite handler for DAX files. Assumes the caller has done all the * necessary locking for the page fault to proceed successfully. */ -int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, +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; + unsigned long vaddr = vmf->address; loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; sector_t sector; struct iomap iomap = { 0 }; - unsigned flags = 0; + unsigned flags = IOMAP_FAULT; int error, major = 0; + int vmf_ret = 0; void *entry; /* @@ -1386,12 +1144,6 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, if (pos >= i_size_read(inode)) return VM_FAULT_SIGBUS; - entry = grab_mapping_entry(mapping, vmf->pgoff); - if (IS_ERR(entry)) { - error = PTR_ERR(entry); - goto out; - } - if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) flags |= IOMAP_WRITE; @@ -1402,13 +1154,19 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, */ error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); if (error) - goto unlock_entry; + return dax_fault_return(error); if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { - error = -EIO; /* fs corruption? */ - goto unlock_entry; + vmf_ret = dax_fault_return(-EIO); /* fs corruption? */ + goto finish_iomap; + } + + entry = grab_mapping_entry(mapping, vmf->pgoff, 0); + if (IS_ERR(entry)) { + vmf_ret = dax_fault_return(PTR_ERR(entry)); + goto finish_iomap; } - sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9); + sector = dax_iomap_sector(&iomap, pos); if (vmf->cow_page) { switch (iomap.type) { @@ -1427,13 +1185,13 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } if (error) - goto unlock_entry; - if (!radix_tree_exceptional_entry(entry)) { - vmf->page = entry; - return VM_FAULT_LOCKED; - } - vmf->entry = entry; - return VM_FAULT_DAX_LOCKED; + goto error_unlock_entry; + + __SetPageUptodate(vmf->cow_page); + vmf_ret = finish_fault(vmf); + if (!vmf_ret) + vmf_ret = VM_FAULT_DONE_COW; + goto unlock_entry; } switch (iomap.type) { @@ -1445,11 +1203,16 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } error = dax_insert_mapping(mapping, iomap.bdev, sector, PAGE_SIZE, &entry, vma, vmf); + /* -EBUSY is fine, somebody else faulted on the same PTE */ + if (error == -EBUSY) + error = 0; break; case IOMAP_UNWRITTEN: case IOMAP_HOLE: - if (!(vmf->flags & FAULT_FLAG_WRITE)) - return dax_load_hole(mapping, entry, vmf); + if (!(vmf->flags & FAULT_FLAG_WRITE)) { + vmf_ret = dax_load_hole(mapping, &entry, vmf); + goto unlock_entry; + } /*FALLTHRU*/ default: WARN_ON_ONCE(1); @@ -1457,15 +1220,215 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, break; } + error_unlock_entry: + vmf_ret = dax_fault_return(error) | major; unlock_entry: 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; - return VM_FAULT_NOPAGE | major; + finish_iomap: + if (ops->iomap_end) { + int copied = PAGE_SIZE; + + if (vmf_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); + } + return vmf_ret; +} +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; + + /* + * 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 fallback; + + if (iomap.offset + iomap.length < pos + PMD_SIZE) + goto finish_iomap; + + /* + * 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 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 unlock_entry; + result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap, + &entry); + break; + default: + WARN_ON_ONCE(1); + break; + } + + unlock_entry: + put_locked_mapping_entry(mapping, pgoff, entry); + 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); + } + fallback: + if (result == VM_FAULT_FALLBACK) { + split_huge_pmd(vma, pmd, address); + count_vm_event(THP_FAULT_FALLBACK); + } + return result; } -EXPORT_SYMBOL_GPL(iomap_dax_fault); -#endif /* CONFIG_FS_IOMAP */ +EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault); +#endif /* CONFIG_FS_DAX_PMD */ |