linux-kernel - [PATCH 1/7] userfaultfd: introduce vma_can

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Message-Id: <1470298458-9925-2-git-send-email-rppt@linux.vnet.ibm.com>
Date:	Thu,  4 Aug 2016 11:14:12 +0300
From:	Mike Rapoport <rppt@...ux.vnet.ibm.com>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Hugh Dickins <hughd@...gle.com>,
	Pavel Emelyanov <xemul@...tuozzo.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Mike Rapoport <rppt@...ux.vnet.ibm.com>
Subject: [PATCH 1/7] userfaultfd: introduce vma_can_userfault

Check whether a VMA can be used with userfault in more compact way

Signed-off-by: Mike Rapoport <rppt@...ux.vnet.ibm.com>
---
 fs/userfaultfd.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index f48f709..2aab2e1 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1066,6 +1066,11 @@ static __always_inline int validate_range(struct mm_struct *mm,
 	return 0;
 }
 
+static inline bool vma_can_userfault(struct vm_area_struct *vma)
+{
+	return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma);
+}
+
 static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 				unsigned long arg)
 {
@@ -1148,7 +1153,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 
 		/* check not compatible vmas */
 		ret = -EINVAL;
-		if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
+		if (!vma_can_userfault(cur))
 			goto out_unlock;
 		/* FIXME: add WP support to hugetlbfs */
 		if (is_vm_hugetlb_page(cur) && vm_flags & VM_UFFD_WP)
@@ -1197,7 +1202,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	do {
 		cond_resched();
 
-		BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
+		BUG_ON(!vma_can_userfault(vma));
 		BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
 		       vma->vm_userfaultfd_ctx.ctx != ctx);
 
@@ -1335,7 +1340,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		 * provides for more strict behavior to notice
 		 * unregistration errors.
 		 */
-		if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
+		if (!vma_can_userfault(cur))
 			goto out_unlock;
 
 		found = true;
@@ -1349,7 +1354,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	do {
 		cond_resched();
 
-		BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
+		BUG_ON(!vma_can_userfault(vma));
 
 		/*
 		 * Nothing to do: this vma is already registered into this
-- 
1.9.1