1 files changed, 236 insertions, 39 deletions

diff --git a/fs/dax.c b/fs/dax.c
index c3e21ccfc358..93bf2f990ace 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -17,12 +17,14 @@
 #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/pmem.h>
 #include <linux/sched.h>
 #include <linux/uio.h>
 #include <linux/vmstat.h>
@@ -34,7 +36,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 
 	might_sleep();
 	do {
-		void *addr;
+		void __pmem *addr;
 		unsigned long pfn;
 		long count;
 
@@ -46,10 +48,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 			unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
 			if (pgsz > count)
 				pgsz = count;
-			if (pgsz < PAGE_SIZE)
-				memset(addr, 0, pgsz);
-			else
-				clear_page(addr);
+			clear_pmem(addr, pgsz);
 			addr += pgsz;
 			size -= pgsz;
 			count -= pgsz;
@@ -59,26 +58,29 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 		}
 	} while (size);
 
+	wmb_pmem();
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dax_clear_blocks);
 
-static long dax_get_addr(struct buffer_head *bh, void **addr, unsigned blkbits)
+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);
 }
 
-static void dax_new_buf(void *addr, unsigned size, unsigned first, loff_t pos,
-			loff_t end)
+/* 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,
+		loff_t pos, loff_t end)
 {
 	loff_t final = end - pos + first; /* The final byte of the buffer */
 
 	if (first > 0)
-		memset(addr, 0, first);
+		clear_pmem(addr, first);
 	if (final < size)
-		memset(addr + final, 0, size - final);
+		clear_pmem(addr + final, size - final);
 }
 
 static bool buffer_written(struct buffer_head *bh)
@@ -106,14 +108,15 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 	loff_t pos = start;
 	loff_t max = start;
 	loff_t bh_max = start;
-	void *addr;
+	void __pmem *addr;
 	bool hole = false;
+	bool need_wmb = false;
 
 	if (iov_iter_rw(iter) != WRITE)
 		end = min(end, i_size_read(inode));
 
 	while (pos < end) {
-		unsigned len;
+		size_t len;
 		if (pos == max) {
 			unsigned blkbits = inode->i_blkbits;
 			sector_t block = pos >> blkbits;
@@ -145,19 +148,23 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 				retval = dax_get_addr(bh, &addr, blkbits);
 				if (retval < 0)
 					break;
-				if (buffer_unwritten(bh) || buffer_new(bh))
+				if (buffer_unwritten(bh) || buffer_new(bh)) {
 					dax_new_buf(addr, retval, first, pos,
 									end);
+					need_wmb = true;
+				}
 				addr += first;
 				size = retval - first;
 			}
 			max = min(pos + size, end);
 		}
 
-		if (iov_iter_rw(iter) == WRITE)
-			len = copy_from_iter_nocache(addr, max - pos, iter);
-		else if (!hole)
-			len = copy_to_iter(addr, max - pos, iter);
+		if (iov_iter_rw(iter) == WRITE) {
+			len = copy_from_iter_pmem(addr, max - pos, iter);
+			need_wmb = true;
+		} else if (!hole)
+			len = copy_to_iter((void __force *)addr, max - pos,
+					iter);
 		else
 			len = iov_iter_zero(max - pos, iter);
 
@@ -168,6 +175,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 		addr += len;
 	}
 
+	if (need_wmb)
+		wmb_pmem();
+
 	return (pos == start) ? retval : pos - start;
 }
 
@@ -260,11 +270,13 @@ static int dax_load_hole(struct address_space *mapping, struct page *page,
 static int copy_user_bh(struct page *to, struct buffer_head *bh,
 			unsigned blkbits, unsigned long vaddr)
 {
-	void *vfrom, *vto;
+	void __pmem *vfrom;
+	void *vto;
+
 	if (dax_get_addr(bh, &vfrom, blkbits) < 0)
 		return -EIO;
 	vto = kmap_atomic(to);
-	copy_user_page(vto, vfrom, vaddr, to);
+	copy_user_page(vto, (void __force *)vfrom, vaddr, to);
 	kunmap_atomic(vto);
 	return 0;
 }
@@ -272,16 +284,13 @@ static int copy_user_bh(struct page *to, struct buffer_head *bh,
 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 *addr;
+	void __pmem *addr;
 	unsigned long pfn;
 	pgoff_t size;
 	int error;
 
-	i_mmap_lock_read(mapping);
-
 	/*
 	 * Check truncate didn't happen while we were allocating a block.
 	 * If it did, this block may or may not be still allocated to the
@@ -303,14 +312,14 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 		goto out;
 	}
 
-	if (buffer_unwritten(bh) || buffer_new(bh))
-		clear_page(addr);
+	if (buffer_unwritten(bh) || buffer_new(bh)) {
+		clear_pmem(addr, PAGE_SIZE);
+		wmb_pmem();
+	}
 
 	error = vm_insert_mixed(vma, vaddr, pfn);
 
  out:
-	i_mmap_unlock_read(mapping);
-
 	return error;
 }
 
@@ -319,6 +328,12 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
  * @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
+ * @complete_unwritten: The filesystem method used to convert unwritten blocks
+ *	to written so the data written to them is exposed. This is required for
+ *	required by write faults for filesystems that will return unwritten
+ *	extent mappings from @get_block, but it is optional for reads as
+ *	dax_insert_mapping() will always zero unwritten blocks. If the fs does
+ *	not support unwritten extents, the it should pass NULL.
  *
  * 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
@@ -366,15 +381,17 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 			 * from a read fault and we've raced with a truncate
 			 */
 			error = -EIO;
-			goto unlock_page;
+			goto unlock;
 		}
+	} else {
+		i_mmap_lock_write(mapping);
 	}
 
 	error = get_block(inode, block, &bh, 0);
 	if (!error && (bh.b_size < PAGE_SIZE))
 		error = -EIO;		/* fs corruption? */
 	if (error)
-		goto unlock_page;
+		goto unlock;
 
 	if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
 		if (vmf->flags & FAULT_FLAG_WRITE) {
@@ -385,8 +402,9 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 			if (!error && (bh.b_size < PAGE_SIZE))
 				error = -EIO;
 			if (error)
-				goto unlock_page;
+				goto unlock;
 		} else {
+			i_mmap_unlock_write(mapping);
 			return dax_load_hole(mapping, page, vmf);
 		}
 	}
@@ -398,17 +416,15 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		else
 			clear_user_highpage(new_page, vaddr);
 		if (error)
-			goto unlock_page;
+			goto unlock;
 		vmf->page = page;
 		if (!page) {
-			i_mmap_lock_read(mapping);
 			/* Check we didn't race with truncate */
 			size = (i_size_read(inode) + PAGE_SIZE - 1) >>
 								PAGE_SHIFT;
 			if (vmf->pgoff >= size) {
-				i_mmap_unlock_read(mapping);
 				error = -EIO;
-				goto out;
+				goto unlock;
 			}
 		}
 		return VM_FAULT_LOCKED;
@@ -437,9 +453,15 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 	 * as for normal BH based IO completions.
 	 */
 	error = dax_insert_mapping(inode, &bh, vma, vmf);
-	if (buffer_unwritten(&bh))
-		complete_unwritten(&bh, !error);
+	if (buffer_unwritten(&bh)) {
+		if (complete_unwritten)
+			complete_unwritten(&bh, !error);
+		else
+			WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
+	}
 
+	if (!page)
+		i_mmap_unlock_write(mapping);
  out:
 	if (error == -ENOMEM)
 		return VM_FAULT_OOM | major;
@@ -448,11 +470,14 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		return VM_FAULT_SIGBUS | major;
 	return VM_FAULT_NOPAGE | major;
 
- unlock_page:
+ unlock:
 	if (page) {
 		unlock_page(page);
 		page_cache_release(page);
+	} else {
+		i_mmap_unlock_write(mapping);
 	}
+
 	goto out;
 }
 EXPORT_SYMBOL(__dax_fault);
@@ -484,6 +509,177 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 }
 EXPORT_SYMBOL_GPL(dax_fault);
 
+#ifdef 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)
+
+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)
+{
+	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;
+	long length;
+	void __pmem *kaddr;
+	pgoff_t size, pgoff;
+	sector_t block, sector;
+	unsigned long pfn;
+	int result = 0;
+
+	/* Fall back to PTEs if we're going to COW */
+	if (write && !(vma->vm_flags & VM_SHARED))
+		return VM_FAULT_FALLBACK;
+	/* If the PMD would extend outside the VMA */
+	if (pmd_addr < vma->vm_start)
+		return VM_FAULT_FALLBACK;
+	if ((pmd_addr + PMD_SIZE) > vma->vm_end)
+		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)
+		return VM_FAULT_FALLBACK;
+
+	memset(&bh, 0, sizeof(bh));
+	block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
+
+	bh.b_size = PMD_SIZE;
+	i_mmap_lock_write(mapping);
+	length = get_block(inode, block, &bh, write);
+	if (length)
+		return VM_FAULT_SIGBUS;
+
+	/*
+	 * 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_unwritten(&bh) || buffer_new(&bh)) {
+		int i;
+		for (i = 0; i < PTRS_PER_PMD; i++)
+			clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
+		wmb_pmem();
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+		result |= VM_FAULT_MAJOR;
+	}
+
+	/*
+	 * If we allocated new storage, make sure no process has any
+	 * zero pages covering this hole
+	 */
+	if (buffer_new(&bh)) {
+		i_mmap_unlock_write(mapping);
+		unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
+		i_mmap_lock_write(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
+	 * take i_mutex here, so just leave them hanging; they'll be freed
+	 * when the file is deleted.
+	 */
+	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (pgoff >= size) {
+		result = VM_FAULT_SIGBUS;
+		goto out;
+	}
+	if ((pgoff | PG_PMD_COLOUR) >= 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))
+			goto fallback;
+
+		ptl = pmd_lock(vma->vm_mm, pmd);
+		if (!pmd_none(*pmd)) {
+			spin_unlock(ptl);
+			goto fallback;
+		}
+
+		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);
+		if (length < 0) {
+			result = VM_FAULT_SIGBUS;
+			goto out;
+		}
+		if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
+			goto fallback;
+
+		result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
+	}
+
+ out:
+	if (buffer_unwritten(&bh))
+		complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
+
+	i_mmap_unlock_write(mapping);
+
+	return result;
+
+ fallback:
+	count_vm_event(THP_FAULT_FALLBACK);
+	result = VM_FAULT_FALLBACK;
+	goto out;
+}
+EXPORT_SYMBOL_GPL(__dax_pmd_fault);
+
+/**
+ * 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,
+			dax_iodone_t complete_unwritten)
+{
+	int result;
+	struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+
+	if (flags & FAULT_FLAG_WRITE) {
+		sb_start_pagefault(sb);
+		file_update_time(vma->vm_file);
+	}
+	result = __dax_pmd_fault(vma, address, pmd, flags, get_block,
+				complete_unwritten);
+	if (flags & FAULT_FLAG_WRITE)
+		sb_end_pagefault(sb);
+
+	return result;
+}
+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
@@ -538,11 +734,12 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
 	if (err < 0)
 		return err;
 	if (buffer_written(&bh)) {
-		void *addr;
+		void __pmem *addr;
 		err = dax_get_addr(&bh, &addr, inode->i_blkbits);
 		if (err < 0)
 			return err;
-		memset(addr + offset, 0, length);
+		clear_pmem(addr + offset, length);
+		wmb_pmem();
 	}
 
 	return 0;