5 files changed, 165 insertions, 80 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 180f910339f4..3b713b6fcc26 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -202,12 +202,12 @@ static struct ratelimit_state printk_limits[] = {
 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 {
 	struct super_block *sb = fs_info->sb;
-	char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1];
+	char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
 	struct va_format vaf;
 	va_list args;
-	const char *type = NULL;
 	int kern_level;
-	struct ratelimit_state *ratelimit;
+	const char *type = logtypes[4];
+	struct ratelimit_state *ratelimit = &printk_limits[4];
 
 	va_start(args, fmt);
 
@@ -223,12 +223,6 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 		fmt += size;
 	}
 
-	if (!type) {
-		*lvl = '\0';
-		type = logtypes[4];
-		ratelimit = &printk_limits[4];
-	}
-
 	vaf.fmt = fmt;
 	vaf.va = &args;
 
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index bf62ad919a95..00ee006a8aa2 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -162,6 +162,7 @@ void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
 				slot = radix_tree_iter_retry(&iter);
 			continue;
 		}
+		slot = radix_tree_iter_resume(slot, &iter);
 		spin_unlock(&fs_info->buffer_lock);
 		free_extent_buffer_stale(eb);
 		spin_lock(&fs_info->buffer_lock);
diff --git a/fs/dax.c b/fs/dax.c
index 5ae8e11ad786..a8732fbed381 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -31,6 +31,7 @@
 #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"
 
@@ -240,6 +241,23 @@ 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)
 {
@@ -433,22 +451,6 @@ void dax_wake_mapping_entry_waiter(struct address_space *mapping,
 		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
 }
 
-void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index)
-{
-	void *entry, **slot;
-
-	spin_lock_irq(&mapping->tree_lock);
-	entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
-	if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
-			 !slot_locked(mapping, slot))) {
-		spin_unlock_irq(&mapping->tree_lock);
-		return;
-	}
-	unlock_slot(mapping, slot);
-	spin_unlock_irq(&mapping->tree_lock);
-	dax_wake_mapping_entry_waiter(mapping, index, entry, false);
-}
-
 /*
  * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
  * entry to get unlocked before deleting it.
@@ -500,10 +502,8 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
 	/* 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;
-	}
 	vmf->page = page;
 	return VM_FAULT_LOCKED;
 }
@@ -615,36 +615,107 @@ 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 *ptep;
+	pte_t pte;
+	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(vma->vm_mm, address, &ptep, &ptl))
+			continue;
+		if (pfn != pte_pfn(*ptep))
+			goto unlock;
+		if (!pte_dirty(*ptep) && !pte_write(*ptep))
+			goto unlock;
+
+		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_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;
-	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;
 
+	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;
 	}
 
+	/* 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
@@ -654,31 +725,40 @@ static int dax_writeback_one(struct block_device *bdev,
 	 */
 	dax.sector = dax_radix_sector(entry);
 	dax.size = PAGE_SIZE << dax_radix_order(entry);
-	spin_unlock_irq(&mapping->tree_lock);
 
 	/*
 	 * We cannot hold tree_lock while calling dax_map_atomic() because it
 	 * eventually calls cond_resched().
 	 */
 	ret = dax_map_atomic(bdev, &dax);
-	if (ret < 0)
+	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;
 }
@@ -738,7 +818,7 @@ 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,
@@ -767,17 +847,27 @@ 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);
@@ -948,13 +1038,13 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 {
 	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 = IOMAP_FAULT;
 	int error, major = 0;
-	int locked_status = 0;
+	int vmf_ret = 0;
 	void *entry;
 
 	/*
@@ -1007,13 +1097,11 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 
 		if (error)
 			goto finish_iomap;
-		if (!radix_tree_exceptional_entry(entry)) {
-			vmf->page = entry;
-			locked_status = VM_FAULT_LOCKED;
-		} else {
-			vmf->entry = entry;
-			locked_status = VM_FAULT_DAX_LOCKED;
-		}
+
+		__SetPageUptodate(vmf->cow_page);
+		vmf_ret = finish_fault(vmf);
+		if (!vmf_ret)
+			vmf_ret = VM_FAULT_DONE_COW;
 		goto finish_iomap;
 	}
 
@@ -1030,7 +1118,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 	case IOMAP_UNWRITTEN:
 	case IOMAP_HOLE:
 		if (!(vmf->flags & FAULT_FLAG_WRITE)) {
-			locked_status = dax_load_hole(mapping, entry, vmf);
+			vmf_ret = dax_load_hole(mapping, entry, vmf);
 			break;
 		}
 		/*FALLTHRU*/
@@ -1042,7 +1130,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 
  finish_iomap:
 	if (ops->iomap_end) {
-		if (error) {
+		if (error || (vmf_ret & VM_FAULT_ERROR)) {
 			/* keep previous error */
 			ops->iomap_end(inode, pos, PAGE_SIZE, 0, flags,
 					&iomap);
@@ -1052,7 +1140,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		}
 	}
  unlock_entry:
-	if (!locked_status || error)
+	if (vmf_ret != VM_FAULT_LOCKED || error)
 		put_locked_mapping_entry(mapping, vmf->pgoff, entry);
  out:
 	if (error == -ENOMEM)
@@ -1060,9 +1148,9 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 	/* -EBUSY is fine, somebody else faulted on the same PTE */
 	if (error < 0 && error != -EBUSY)
 		return VM_FAULT_SIGBUS | major;
-	if (locked_status) {
+	if (vmf_ret) {
 		WARN_ON_ONCE(error); /* -EBUSY from ops->iomap_end? */
-		return locked_status;
+		return vmf_ret;
 	}
 	return VM_FAULT_NOPAGE | major;
 }
diff --git a/fs/exec.c b/fs/exec.c
index 88b5e1efdbd6..8112eacf10f3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -209,7 +209,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 	 * doing the exec and bprm->mm is the new process's mm.
 	 */
 	ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
-			&page, NULL);
+			&page, NULL, NULL);
 	if (ret <= 0)
 		return NULL;
 
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 85959d8324df..d96e2f30084b 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -257,9 +257,9 @@ out:
  * fatal_signal_pending()s, and the mmap_sem must be released before
  * returning it.
  */
-int handle_userfault(struct fault_env *fe, unsigned long reason)
+int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 {
-	struct mm_struct *mm = fe->vma->vm_mm;
+	struct mm_struct *mm = vmf->vma->vm_mm;
 	struct userfaultfd_ctx *ctx;
 	struct userfaultfd_wait_queue uwq;
 	int ret;
@@ -268,7 +268,7 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
 
 	ret = VM_FAULT_SIGBUS;
-	ctx = fe->vma->vm_userfaultfd_ctx.ctx;
+	ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
 	if (!ctx)
 		goto out;
 
@@ -301,17 +301,18 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	 * without first stopping userland access to the memory. For
 	 * VM_UFFD_MISSING userfaults this is enough for now.
 	 */
-	if (unlikely(!(fe->flags & FAULT_FLAG_ALLOW_RETRY))) {
+	if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) {
 		/*
 		 * Validate the invariant that nowait must allow retry
 		 * to be sure not to return SIGBUS erroneously on
 		 * nowait invocations.
 		 */
-		BUG_ON(fe->flags & FAULT_FLAG_RETRY_NOWAIT);
+		BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT);
 #ifdef CONFIG_DEBUG_VM
 		if (printk_ratelimit()) {
 			printk(KERN_WARNING
-			       "FAULT_FLAG_ALLOW_RETRY missing %x\n", fe->flags);
+			       "FAULT_FLAG_ALLOW_RETRY missing %x\n",
+			       vmf->flags);
 			dump_stack();
 		}
 #endif
@@ -323,7 +324,7 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 	 * and wait.
 	 */
 	ret = VM_FAULT_RETRY;
-	if (fe->flags & FAULT_FLAG_RETRY_NOWAIT)
+	if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
 		goto out;
 
 	/* take the reference before dropping the mmap_sem */
@@ -331,11 +332,11 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 
 	init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function);
 	uwq.wq.private = current;
-	uwq.msg = userfault_msg(fe->address, fe->flags, reason);
+	uwq.msg = userfault_msg(vmf->address, vmf->flags, reason);
 	uwq.ctx = ctx;
 
 	return_to_userland =
-		(fe->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
+		(vmf->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) ==
 		(FAULT_FLAG_USER|FAULT_FLAG_KILLABLE);
 
 	spin_lock(&ctx->fault_pending_wqh.lock);
@@ -353,7 +354,8 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
 			  TASK_KILLABLE);
 	spin_unlock(&ctx->fault_pending_wqh.lock);
 
-	must_wait = userfaultfd_must_wait(ctx, fe->address, fe->flags, reason);
+	must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
+					  reason);
 	up_read(&mm->mmap_sem);
 
 	if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&