Merge branch 'akpm' (patches from Andrew)

Merge second patch-bomb from Andrew Morton:
 "Almost all of the rest of MM.  There was an unusually large amount of
  MM material this time"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (141 commits)
  zpool: remove no-op module init/exit
  mm: zbud: constify the zbud_ops
  mm: zpool: constify the zpool_ops
  mm: swap: zswap: maybe_preload & refactoring
  zram: unify error reporting
  zsmalloc: remove null check from destroy_handle_cache()
  zsmalloc: do not take class lock in zs_shrinker_count()
  zsmalloc: use class->pages_per_zspage
  zsmalloc: consider ZS_ALMOST_FULL as migrate source
  zsmalloc: partial page ordering within a fullness_list
  zsmalloc: use shrinker to trigger auto-compaction
  zsmalloc: account the number of compacted pages
  zsmalloc/zram: introduce zs_pool_stats api
  zsmalloc: cosmetic compaction code adjustments
  zsmalloc: introduce zs_can_compact() function
  zsmalloc: always keep per-class stats
  zsmalloc: drop unused variable `nr_to_migrate'
  mm/memblock.c: fix comment in __next_mem_range()
  mm/page_alloc.c: fix type information of memoryless node
  memory-hotplug: fix comments in zone_spanned_pages_in_node() and zone_spanned_pages_in_node()
  ...

1 files changed, 184 insertions, 13 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 57bb70b4af70..e43389c74bbc 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -283,7 +283,6 @@ 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 __pmem *addr;
@@ -291,8 +290,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 	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
@@ -322,8 +319,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 	error = vm_insert_mixed(vma, vaddr, pfn);
 
  out:
-	i_mmap_unlock_read(mapping);
-
 	return error;
 }
 
@@ -385,15 +380,17 @@ 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) {
@@ -404,8 +401,9 @@ 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);
 		}
 	}
@@ -417,17 +415,15 @@ 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;
@@ -463,6 +459,8 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 			WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
 	}
 
+	if (!page)
+		i_mmap_unlock_write(mapping);
  out:
 	if (error == -ENOMEM)
 		return VM_FAULT_OOM | major;
@@ -471,11 +469,14 @@ 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);
@@ -507,6 +508,176 @@ 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 *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_page(kaddr + i * PAGE_SIZE);
+		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