[PATCH 14/43] userfaultfd: Use vma iterator

[Liam Howlett <liam.howlett@oracle.com>]

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Use the vma iterator so that the iterator can be invalidated or updated
to avoid each caller doing so.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 fs/userfaultfd.c | 88 +++++++++++++++++++-----------------------------
 1 file changed, 34 insertions(+), 54 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 98ac37e34e3d..b3249388696a 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -857,7 +857,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 	/* len == 0 means wake all */
 	struct userfaultfd_wake_range range = { .len = 0, };
 	unsigned long new_flags;
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	VMA_ITERATOR(vmi, mm, 0);
 
 	WRITE_ONCE(ctx->released, true);
 
@@ -874,7 +874,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 	 */
 	mmap_write_lock(mm);
 	prev = NULL;
-	mas_for_each(&mas, vma, ULONG_MAX) {
+	for_each_vma(vmi, vma) {
 		cond_resched();
 		BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^
 		       !!(vma->vm_flags & __VM_UFFD_FLAGS));
@@ -883,13 +883,12 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 			continue;
 		}
 		new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS;
-		prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
+		prev = vmi_vma_merge(&vmi, mm, prev, vma->vm_start, vma->vm_end,
 				 new_flags, vma->anon_vma,
 				 vma->vm_file, vma->vm_pgoff,
 				 vma_policy(vma),
 				 NULL_VM_UFFD_CTX, anon_vma_name(vma));
 		if (prev) {
-			mas_pause(&mas);
 			vma = prev;
 		} else {
 			prev = vma;
@@ -1276,7 +1275,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	bool found;
 	bool basic_ioctls;
 	unsigned long start, end, vma_end;
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	struct vma_iterator vmi;
 
 	user_uffdio_register = (struct uffdio_register __user *) arg;
 
@@ -1318,17 +1317,13 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	if (!mmget_not_zero(mm))
 		goto out;
 
+	ret = -EINVAL;
 	mmap_write_lock(mm);
-	mas_set(&mas, start);
-	vma = mas_find(&mas, ULONG_MAX);
+	vma_iter_init(&vmi, mm, start);
+	vma = vma_find(&vmi, end);
 	if (!vma)
 		goto out_unlock;
 
-	/* check that there's at least one vma in the range */
-	ret = -EINVAL;
-	if (vma->vm_start >= end)
-		goto out_unlock;
-
 	/*
 	 * If the first vma contains huge pages, make sure start address
 	 * is aligned to huge page size.
@@ -1345,7 +1340,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	 */
 	found = false;
 	basic_ioctls = false;
-	for (cur = vma; cur; cur = mas_next(&mas, end - 1)) {
+	cur = vma;
+	do {
 		cond_resched();
 
 		BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1402,16 +1398,14 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 			basic_ioctls = true;
 
 		found = true;
-	}
+	} for_each_vma_range(vmi, cur, end);
 	BUG_ON(!found);
 
-	mas_set(&mas, start);
-	prev = mas_prev(&mas, 0);
-	if (prev != vma)
-		mas_next(&mas, ULONG_MAX);
+	vma_iter_set(&vmi, start);
+	prev = vma_prev(&vmi);
 
 	ret = 0;
-	do {
+	for_each_vma_range(vmi, vma, end) {
 		cond_resched();
 
 		BUG_ON(!vma_can_userfault(vma, vm_flags));
@@ -1432,30 +1426,25 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		vma_end = min(end, vma->vm_end);
 
 		new_flags = (vma->vm_flags & ~__VM_UFFD_FLAGS) | vm_flags;
-		prev = vma_merge(mm, prev, start, vma_end, new_flags,
+		prev = vmi_vma_merge(&vmi, mm, prev, start, vma_end, new_flags,
 				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
 				 vma_policy(vma),
 				 ((struct vm_userfaultfd_ctx){ ctx }),
 				 anon_vma_name(vma));
 		if (prev) {
 			/* vma_merge() invalidated the mas */
-			mas_pause(&mas);
 			vma = prev;
 			goto next;
 		}
 		if (vma->vm_start < start) {
-			ret = split_vma(mm, vma, start, 1);
+			ret = vmi_split_vma(&vmi, mm, vma, start, 1);
 			if (ret)
 				break;
-			/* split_vma() invalidated the mas */
-			mas_pause(&mas);
 		}
 		if (vma->vm_end > end) {
-			ret = split_vma(mm, vma, end, 0);
+			ret = vmi_split_vma(&vmi, mm, vma, end, 0);
 			if (ret)
 				break;
-			/* split_vma() invalidated the mas */
-			mas_pause(&mas);
 		}
 	next:
 		/*
@@ -1472,8 +1461,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	skip:
 		prev = vma;
 		start = vma->vm_end;
-		vma = mas_next(&mas, end - 1);
-	} while (vma);
+	}
+
 out_unlock:
 	mmap_write_unlock(mm);
 	mmput(mm);
@@ -1517,7 +1506,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	bool found;
 	unsigned long start, end, vma_end;
 	const void __user *buf = (void __user *)arg;
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	struct vma_iterator vmi;
 
 	ret = -EFAULT;
 	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
@@ -1536,14 +1525,10 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		goto out;
 
 	mmap_write_lock(mm);
-	mas_set(&mas, start);
-	vma = mas_find(&mas, ULONG_MAX);
-	if (!vma)
-		goto out_unlock;
-
-	/* check that there's at least one vma in the range */
 	ret = -EINVAL;
-	if (vma->vm_start >= end)
+	vma_iter_init(&vmi, mm, start);
+	vma = vma_find(&vmi, end);
+	if (!vma)
 		goto out_unlock;
 
 	/*
@@ -1561,8 +1546,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	 * Search for not compatible vmas.
 	 */
 	found = false;
-	ret = -EINVAL;
-	for (cur = vma; cur; cur = mas_next(&mas, end - 1)) {
+	cur = vma;
+	do {
 		cond_resched();
 
 		BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1579,16 +1564,13 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 			goto out_unlock;
 
 		found = true;
-	}
+	} for_each_vma_range(vmi, cur, end);
 	BUG_ON(!found);
 
-	mas_set(&mas, start);
-	prev = mas_prev(&mas, 0);
-	if (prev != vma)
-		mas_next(&mas, ULONG_MAX);
-
+	vma_iter_set(&vmi, start);
+	prev = vma_prev(&vmi);
 	ret = 0;
-	do {
+	for_each_vma_range(vmi, vma, end) {
 		cond_resched();
 
 		BUG_ON(!vma_can_userfault(vma, vma->vm_flags));
@@ -1624,26 +1606,24 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 			uffd_wp_range(mm, vma, start, vma_end - start, false);
 
 		new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS;
-		prev = vma_merge(mm, prev, start, vma_end, new_flags,
+		prev = vmi_vma_merge(&vmi, mm, prev, start, vma_end, new_flags,
 				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
 				 vma_policy(vma),
 				 NULL_VM_UFFD_CTX, anon_vma_name(vma));
 		if (prev) {
 			vma = prev;
-			mas_pause(&mas);
 			goto next;
 		}
 		if (vma->vm_start < start) {
-			ret = split_vma(mm, vma, start, 1);
+			ret = vmi_split_vma(&vmi, mm, vma, start, 1);
 			if (ret)
 				break;
-			mas_pause(&mas);
 		}
 		if (vma->vm_end > end) {
-			ret = split_vma(mm, vma, end, 0);
+			vma_iter_set(&vmi, vma->vm_end);
+			ret = vmi_split_vma(&vmi, mm, vma, end, 0);
 			if (ret)
 				break;
-			mas_pause(&mas);
 		}
 	next:
 		/*
@@ -1657,8 +1637,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	skip:
 		prev = vma;
 		start = vma->vm_end;
-		vma = mas_next(&mas, end - 1);
-	} while (vma);
+	}
+
 out_unlock:
 	mmap_write_unlock(mm);
 	mmput(mm);
-- 
2.35.1