linux-kernel - [PATCH 10/14] vgem: separate errno from VM_FAULT

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Message-Id: <20180516054348.15950-11-hch@lst.de>
Date:   Wed, 16 May 2018 07:43:44 +0200
From:   Christoph Hellwig <hch@....de>
To:     Souptick Joarder <jrdr.linux@...il.com>,
        Matthew Wilcox <willy@...radead.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, devel@...ts.orangefs.org,
        ceph-devel@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, ocfs2-devel@....oracle.com,
        linux-mtd@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        lustre-devel@...ts.lustre.org,
        linux-arm-kernel@...ts.infradead.org, linux-s390@...r.kernel.org
Subject: [PATCH 10/14] vgem: separate errno from VM_FAULT_* values

And streamline the code in vgem_fault with early returns so that it is
a little bit more readable.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/gpu/drm/vgem/vgem_drv.c | 51 +++++++++++++++------------------
 1 file changed, 23 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 2524ff116f00..a261e0aab83a 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -61,12 +61,13 @@ static void vgem_gem_free_object(struct drm_gem_object *obj)
 	kfree(vgem_obj);
 }
 
-static int vgem_gem_fault(struct vm_fault *vmf)
+static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_vgem_gem_object *obj = vma->vm_private_data;
 	/* We don't use vmf->pgoff since that has the fake offset */
 	unsigned long vaddr = vmf->address;
+	struct page *page;
 	int ret;
 	loff_t num_pages;
 	pgoff_t page_offset;
@@ -85,35 +86,29 @@ static int vgem_gem_fault(struct vm_fault *vmf)
 		ret = 0;
 	}
 	mutex_unlock(&obj->pages_lock);
-	if (ret) {
-		struct page *page;
-
-		page = shmem_read_mapping_page(
-					file_inode(obj->base.filp)->i_mapping,
-					page_offset);
-		if (!IS_ERR(page)) {
-			vmf->page = page;
-			ret = 0;
-		} else switch (PTR_ERR(page)) {
-			case -ENOSPC:
-			case -ENOMEM:
-				ret = VM_FAULT_OOM;
-				break;
-			case -EBUSY:
-				ret = VM_FAULT_RETRY;
-				break;
-			case -EFAULT:
-			case -EINVAL:
-				ret = VM_FAULT_SIGBUS;
-				break;
-			default:
-				WARN_ON(PTR_ERR(page));
-				ret = VM_FAULT_SIGBUS;
-				break;
-		}
+	if (!ret)
+		return 0;
+
+	page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
+			page_offset);
+	if (!IS_ERR(page)) {
+		vmf->page = page;
+		return 0;
+	}
 
+	switch (PTR_ERR(page)) {
+	case -ENOSPC:
+	case -ENOMEM:
+		return VM_FAULT_OOM;
+	case -EBUSY:
+		return VM_FAULT_RETRY;
+	case -EFAULT:
+	case -EINVAL:
+		return VM_FAULT_SIGBUS;
+	default:
+		WARN_ON(PTR_ERR(page));
+		return VM_FAULT_SIGBUS;
 	}
-	return ret;
 }
 
 static const struct vm_operations_struct vgem_gem_vm_ops = {
-- 
2.17.0