From 03dd4cb26d967f9588437b0fc9cc0e8353322bb7 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Fri, 25 Mar 2016 03:53:42 -0300 Subject: Linux-libre 4.5-gnu --- fs/dax.c | 610 ++++++++++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 489 insertions(+), 121 deletions(-) (limited to 'fs/dax.c') diff --git a/fs/dax.c b/fs/dax.c index 43671b682..bbb2ad783 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -24,57 +24,91 @@ #include #include #include +#include #include #include #include #include +#include +#include + +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 = (void __pmem *) ERR_PTR(-EIO); + if (blk_queue_enter(q, true) != 0) + return rc; + + rc = bdev_direct_access(bdev, dax); + if (rc < 0) { + dax->addr = (void __pmem *) 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); +} + +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_clear_blocks() is called from within transaction context from XFS, + * dax_clear_sectors() is called from within transaction context from XFS, * and hence this means the stack from this point must follow GFP_NOFS * semantics for all operations. */ -int dax_clear_blocks(struct inode *inode, sector_t block, long size) +int dax_clear_sectors(struct block_device *bdev, sector_t _sector, long _size) { - struct block_device *bdev = inode->i_sb->s_bdev; - sector_t sector = block << (inode->i_blkbits - 9); + struct blk_dax_ctl dax = { + .sector = _sector, + .size = _size, + }; might_sleep(); do { - void __pmem *addr; - unsigned long pfn; - long count; + long count, sz; - count = bdev_direct_access(bdev, sector, &addr, &pfn, size); + count = dax_map_atomic(bdev, &dax); if (count < 0) return count; - BUG_ON(size < count); - while (count > 0) { - unsigned pgsz = PAGE_SIZE - offset_in_page(addr); - if (pgsz > count) - pgsz = count; - clear_pmem(addr, pgsz); - addr += pgsz; - size -= pgsz; - count -= pgsz; - BUG_ON(pgsz & 511); - sector += pgsz / 512; - cond_resched(); - } - } while (size); + sz = min_t(long, count, SZ_128K); + clear_pmem(dax.addr, sz); + dax.size -= sz; + dax.sector += sz / 512; + dax_unmap_atomic(bdev, &dax); + cond_resched(); + } while (dax.size); wmb_pmem(); return 0; } -EXPORT_SYMBOL_GPL(dax_clear_blocks); - -static long dax_get_addr(struct buffer_head *bh, void __pmem **addr, - unsigned blkbits) -{ - unsigned long pfn; - sector_t sector = bh->b_blocknr << (blkbits - 9); - return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size); -} +EXPORT_SYMBOL_GPL(dax_clear_sectors); /* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */ static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first, @@ -105,19 +139,29 @@ static bool buffer_size_valid(struct buffer_head *bh) return bh->b_state != 0; } + +static sector_t to_sector(const struct buffer_head *bh, + const struct inode *inode) +{ + sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); + + return sector; +} + 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) { - ssize_t retval = 0; - loff_t pos = start; - loff_t max = start; - loff_t bh_max = start; - void __pmem *addr; - bool hole = false; - bool need_wmb = false; - - if (iov_iter_rw(iter) != WRITE) + loff_t pos = start, max = start, bh_max = start; + bool hole = false, need_wmb = false; + struct block_device *bdev = NULL; + int rw = iov_iter_rw(iter), rc; + long map_len = 0; + struct blk_dax_ctl dax = { + .addr = (void __pmem *) ERR_PTR(-EIO), + }; + + if (rw == READ) end = min(end, i_size_read(inode)); while (pos < end) { @@ -132,13 +176,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, if (pos == bh_max) { bh->b_size = PAGE_ALIGN(end - pos); bh->b_state = 0; - retval = get_block(inode, block, bh, - iov_iter_rw(iter) == WRITE); - if (retval) + 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; } else { unsigned done = bh->b_size - (bh_max - (pos - first)); @@ -146,47 +190,53 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, bh->b_size -= done; } - hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh); + hole = rw == READ && !buffer_written(bh); if (hole) { - addr = NULL; size = bh->b_size - first; } else { - retval = dax_get_addr(bh, &addr, blkbits); - if (retval < 0) + 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; + } if (buffer_unwritten(bh) || buffer_new(bh)) { - dax_new_buf(addr, retval, first, pos, - end); + dax_new_buf(dax.addr, map_len, first, + pos, end); need_wmb = true; } - addr += first; - size = retval - first; + dax.addr += first; + size = map_len - first; } max = min(pos + size, end); } if (iov_iter_rw(iter) == WRITE) { - len = copy_from_iter_pmem(addr, max - pos, iter); + len = copy_from_iter_pmem(dax.addr, max - pos, iter); need_wmb = true; } else if (!hole) - len = copy_to_iter((void __force *)addr, max - pos, + len = copy_to_iter((void __force *) dax.addr, max - pos, iter); else len = iov_iter_zero(max - pos, iter); if (!len) { - retval = -EFAULT; + rc = -EFAULT; break; } pos += len; - addr += len; + if (!IS_ERR(dax.addr)) + dax.addr += len; } if (need_wmb) wmb_pmem(); + dax_unmap_atomic(bdev, &dax); - return (pos == start) ? retval : pos - start; + return (pos == start) ? rc : pos - start; } /** @@ -215,13 +265,14 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, 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) { struct address_space *mapping = inode->i_mapping; - mutex_lock(&inode->i_mutex); + inode_lock(inode); retval = filemap_write_and_wait_range(mapping, pos, end - 1); if (retval) { - mutex_unlock(&inode->i_mutex); + inode_unlock(inode); goto out; } } @@ -233,7 +284,7 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, retval = dax_io(inode, iter, pos, end, get_block, &bh); if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) - mutex_unlock(&inode->i_mutex); + inode_unlock(inode); if ((retval > 0) && end_io) end_io(iocb, pos, retval, bh.b_private); @@ -275,28 +326,231 @@ static int dax_load_hole(struct address_space *mapping, struct page *page, return VM_FAULT_LOCKED; } -static int copy_user_bh(struct page *to, struct buffer_head *bh, - unsigned blkbits, unsigned long vaddr) +static int copy_user_bh(struct page *to, struct inode *inode, + struct buffer_head *bh, unsigned long vaddr) { - void __pmem *vfrom; + struct blk_dax_ctl dax = { + .sector = to_sector(bh, inode), + .size = bh->b_size, + }; + struct block_device *bdev = bh->b_bdev; void *vto; - if (dax_get_addr(bh, &vfrom, blkbits) < 0) - return -EIO; + if (dax_map_atomic(bdev, &dax) < 0) + return PTR_ERR(dax.addr); vto = kmap_atomic(to); - copy_user_page(vto, (void __force *)vfrom, vaddr, to); + copy_user_page(vto, (void __force *)dax.addr, vaddr, to); kunmap_atomic(vto); + dax_unmap_atomic(bdev, &dax); return 0; } +#define NO_SECTOR -1 +#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_CACHE_SHIFT)) + +static int dax_radix_entry(struct address_space *mapping, pgoff_t index, + sector_t sector, bool pmd_entry, bool dirty) +{ + struct radix_tree_root *page_tree = &mapping->page_tree; + pgoff_t pmd_index = DAX_PMD_INDEX(index); + int type, error = 0; + void *entry; + + WARN_ON_ONCE(pmd_entry && !dirty); + if (dirty) + __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); + + spin_lock_irq(&mapping->tree_lock); + + entry = radix_tree_lookup(page_tree, pmd_index); + if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) { + index = pmd_index; + goto dirty; + } + + entry = radix_tree_lookup(page_tree, index); + if (entry) { + type = RADIX_DAX_TYPE(entry); + if (WARN_ON_ONCE(type != RADIX_DAX_PTE && + type != RADIX_DAX_PMD)) { + error = -EIO; + goto unlock; + } + + if (!pmd_entry || type == RADIX_DAX_PMD) + goto dirty; + + /* + * We only insert dirty PMD entries into the radix tree. This + * means we don't need to worry about removing a dirty PTE + * entry and inserting a clean PMD entry, thus reducing the + * range we would flush with a follow-up fsync/msync call. + */ + radix_tree_delete(&mapping->page_tree, index); + mapping->nrexceptional--; + } + + if (sector == NO_SECTOR) { + /* + * This can happen during correct operation if our pfn_mkwrite + * fault raced against a hole punch operation. If this + * happens the pte that was hole punched will have been + * unmapped and the radix tree entry will have been removed by + * the time we are called, but the call will still happen. We + * will return all the way up to wp_pfn_shared(), where the + * pte_same() check will fail, eventually causing page fault + * to be retried by the CPU. + */ + goto unlock; + } + + error = radix_tree_insert(page_tree, index, + RADIX_DAX_ENTRY(sector, pmd_entry)); + if (error) + goto unlock; + + mapping->nrexceptional++; + dirty: + if (dirty) + radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY); + unlock: + spin_unlock_irq(&mapping->tree_lock); + return error; +} + +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; + 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(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { + ret = -EIO; + goto unlock; + } + + dax.sector = RADIX_DAX_SECTOR(entry); + dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE); + 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, pmd_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; + + if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) + return 0; + + start_index = wbc->range_start >> PAGE_CACHE_SHIFT; + end_index = wbc->range_end >> PAGE_CACHE_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); + + 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; + } + } + wmb_pmem(); + return 0; +} +EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); + static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, struct vm_area_struct *vma, struct vm_fault *vmf) { - struct address_space *mapping = inode->i_mapping; - sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9); unsigned long vaddr = (unsigned long)vmf->virtual_address; - void __pmem *addr; - unsigned long pfn; + struct address_space *mapping = inode->i_mapping; + struct block_device *bdev = bh->b_bdev; + struct blk_dax_ctl dax = { + .sector = to_sector(bh, inode), + .size = bh->b_size, + }; pgoff_t size; int error; @@ -315,20 +569,23 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, goto out; } - error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size); - if (error < 0) - goto out; - if (error < PAGE_SIZE) { - error = -EIO; + if (dax_map_atomic(bdev, &dax) < 0) { + error = PTR_ERR(dax.addr); goto out; } if (buffer_unwritten(bh) || buffer_new(bh)) { - clear_pmem(addr, PAGE_SIZE); + clear_pmem(dax.addr, PAGE_SIZE); wmb_pmem(); } + dax_unmap_atomic(bdev, &dax); - error = vm_insert_mixed(vma, vaddr, pfn); + error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false, + vmf->flags & FAULT_FLAG_WRITE); + if (error) + goto out; + + error = vm_insert_mixed(vma, vaddr, dax.pfn); out: i_mmap_unlock_read(mapping); @@ -373,6 +630,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, 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; repeat: @@ -422,7 +680,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, if (vmf->cow_page) { struct page *new_page = vmf->cow_page; if (buffer_written(&bh)) - error = copy_user_bh(new_page, &bh, blkbits, vaddr); + error = copy_user_bh(new_page, inode, &bh, vaddr); else clear_user_highpage(new_page, vaddr); if (error) @@ -452,6 +710,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, delete_from_page_cache(page); unlock_page(page); page_cache_release(page); + page = NULL; } /* @@ -523,6 +782,24 @@ EXPORT_SYMBOL_GPL(dax_fault); */ #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") + int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, unsigned int flags, get_block_t get_block, dax_iodone_t complete_unwritten) @@ -534,61 +811,83 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, unsigned blkbits = inode->i_blkbits; unsigned long pmd_addr = address & PMD_MASK; bool write = flags & FAULT_FLAG_WRITE; - long length; - void __pmem *kaddr; + struct block_device *bdev; pgoff_t size, pgoff; - sector_t block, sector; - unsigned long pfn; - int result = 0; + sector_t block; + int error, result = 0; + bool alloc = false; - /* dax pmd mappings are broken wrt gup and fork */ + /* 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)) + 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) + 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) + } + 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) + 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; - length = get_block(inode, block, &bh, write); - if (length) + + if (get_block(inode, block, &bh, 0) != 0) return VM_FAULT_SIGBUS; - i_mmap_lock_read(mapping); + + if (!buffer_mapped(&bh) && write) { + if (get_block(inode, block, &bh, 1) != 0) + return VM_FAULT_SIGBUS; + alloc = true; + } + + 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) - goto fallback; + 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 (buffer_new(&bh)) { - i_mmap_unlock_read(mapping); - unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); - i_mmap_lock_read(mapping); + if (alloc) { + loff_t lstart = pgoff << PAGE_SHIFT; + loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */ + + truncate_pagecache_range(inode, lstart, lend); } + i_mmap_lock_read(mapping); + /* * If a truncate happened while we were allocating blocks, we may * leave blocks allocated to the file that are beyond EOF. We can't @@ -600,57 +899,108 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, result = VM_FAULT_SIGBUS; goto out; } - if ((pgoff | PG_PMD_COLOUR) >= size) + if ((pgoff | PG_PMD_COLOUR) >= size) { + dax_pmd_dbg(&bh, address, + "offset + huge page size > file size"); goto fallback; + } if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { spinlock_t *ptl; pmd_t entry; struct page *zero_page = get_huge_zero_page(); - if (unlikely(!zero_page)) + 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: 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 { - sector = bh.b_blocknr << (blkbits - 9); - length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn, - bh.b_size); + struct blk_dax_ctl dax = { + .sector = to_sector(&bh, inode), + .size = PMD_SIZE, + }; + long length = dax_map_atomic(bdev, &dax); + if (length < 0) { result = VM_FAULT_SIGBUS; goto out; } - if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) + 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; + } - /* - * TODO: teach vmf_insert_pfn_pmd() to support - * 'pte_special' for pmds - */ - if (pfn_valid(pfn)) + if (!pfn_t_devmap(dax.pfn)) { + dax_unmap_atomic(bdev, &dax); + dax_pmd_dbg(&bh, address, "pfn not in memmap"); goto fallback; + } if (buffer_unwritten(&bh) || buffer_new(&bh)) { - int i; - for (i = 0; i < PTRS_PER_PMD; i++) - clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE); + clear_pmem(dax.addr, PMD_SIZE); wmb_pmem(); count_vm_event(PGMAJFAULT); mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); result |= VM_FAULT_MAJOR; } + dax_unmap_atomic(bdev, &dax); - result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write); + /* + * 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) { + error = dax_radix_entry(mapping, pgoff, dax.sector, + true, true); + if (error) { + dax_pmd_dbg(&bh, address, + "PMD radix insertion failed"); + goto fallback; + } + } + + 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: @@ -702,15 +1052,27 @@ EXPORT_SYMBOL_GPL(dax_pmd_fault); * 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 super_block *sb = file_inode(vma->vm_file)->i_sb; + struct file *file = vma->vm_file; + int error; + + /* + * We pass NO_SECTOR to dax_radix_entry() because we expect that a + * RADIX_DAX_PTE entry already exists in the radix tree from a + * previous call to __dax_fault(). We just want to look up that PTE + * entry using vmf->pgoff and make sure the dirty tag is set. This + * saves us from having to make a call to get_block() here to look + * up the sector. + */ + error = dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, + true); - sb_start_pagefault(sb); - file_update_time(vma->vm_file); - sb_end_pagefault(sb); + if (error == -ENOMEM) + return VM_FAULT_OOM; + if (error) + return VM_FAULT_SIGBUS; return VM_FAULT_NOPAGE; } EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); @@ -747,17 +1109,23 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, BUG_ON((offset + length) > PAGE_CACHE_SIZE); memset(&bh, 0, sizeof(bh)); + bh.b_bdev = inode->i_sb->s_bdev; bh.b_size = PAGE_CACHE_SIZE; err = get_block(inode, index, &bh, 0); if (err < 0) return err; if (buffer_written(&bh)) { - void __pmem *addr; - err = dax_get_addr(&bh, &addr, inode->i_blkbits); - if (err < 0) - return err; - clear_pmem(addr + offset, length); + struct block_device *bdev = bh.b_bdev; + struct blk_dax_ctl dax = { + .sector = to_sector(&bh, inode), + .size = PAGE_CACHE_SIZE, + }; + + if (dax_map_atomic(bdev, &dax) < 0) + return PTR_ERR(dax.addr); + clear_pmem(dax.addr + offset, length); wmb_pmem(); + dax_unmap_atomic(bdev, &dax); } return 0; -- cgit v1.2.3-54-g00ecf