[RFC PATCH V3 08/10] orangefs: use attach/detach_page_private

[Guoqing Jiang]

Since the new pair function is introduced, we can call them to clean the
code in orangefs.

Cc: Mike Marshall <hubcap@xxxxxxxxxxxx>
Cc: Martin Brandenburg <martin@xxxxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxx
Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
---
RFC V2 -> RFC V3
1. rename clear_page_private to detach_page_private.

RFC -> RFC V2
1. change the name of new functions to attach/clear_page_private.
2. avoid potential use-after-free as suggested by Dave Chinner.

 fs/orangefs/inode.c | 32 ++++++--------------------------
 1 file changed, 6 insertions(+), 26 deletions(-)

diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 12ae630fbed7..48f0547d4850 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -62,12 +62,7 @@ static int orangefs_writepage_locked(struct page *page,
 	} else {
 		ret = 0;
 	}
-	if (wr) {
-		kfree(wr);
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
-		put_page(page);
-	}
+	kfree(detach_page_private(page));
 	return ret;
 }
 
@@ -409,9 +404,7 @@ static int orangefs_write_begin(struct file *file,
 	wr->len = len;
 	wr->uid = current_fsuid();
 	wr->gid = current_fsgid();
-	SetPagePrivate(page);
-	set_page_private(page, (unsigned long)wr);
-	get_page(page);
+	attach_page_private(page, wr);
 okay:
 	return 0;
 }
@@ -459,18 +452,12 @@ static void orangefs_invalidatepage(struct page *page,
 	wr = (struct orangefs_write_range *)page_private(page);
 
 	if (offset == 0 && length == PAGE_SIZE) {
-		kfree((struct orangefs_write_range *)page_private(page));
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
-		put_page(page);
+		kfree(detach_page_private(page));
 		return;
 	/* write range entirely within invalidate range (or equal) */
 	} else if (page_offset(page) + offset <= wr->pos &&
 	    wr->pos + wr->len <= page_offset(page) + offset + length) {
-		kfree((struct orangefs_write_range *)page_private(page));
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
-		put_page(page);
+		kfree(detach_page_private(page));
 		/* XXX is this right? only caller in fs */
 		cancel_dirty_page(page);
 		return;
@@ -535,12 +522,7 @@ static int orangefs_releasepage(struct page *page, gfp_t foo)
 
 static void orangefs_freepage(struct page *page)
 {
-	if (PagePrivate(page)) {
-		kfree((struct orangefs_write_range *)page_private(page));
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
-		put_page(page);
-	}
+	kfree(detach_page_private(page));
 }
 
 static int orangefs_launder_page(struct page *page)
@@ -740,9 +722,7 @@ vm_fault_t orangefs_page_mkwrite(struct vm_fault *vmf)
 	wr->len = PAGE_SIZE;
 	wr->uid = current_fsuid();
 	wr->gid = current_fsgid();
-	SetPagePrivate(page);
-	set_page_private(page, (unsigned long)wr);
-	get_page(page);
+	attach_page_private(page, wr);
 okay:
 
 	file_update_time(vmf->vma->vm_file);
-- 
2.17.1