From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 17 Nov 2015 15:54:32 +0000 (-0500)
Subject: teach shmem_get_link() to work in RCU mode
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6a6c99049635473b64c384135a6906a10df2c916;p=linux.git

teach shmem_get_link() to work in RCU mode

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/mm/shmem.c b/mm/shmem.c
index 684dbc32e2334..0605716aee062 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2501,12 +2501,20 @@ static const char *shmem_get_link(struct dentry *dentry,
 {
 	struct page *page = NULL;
 	int error;
-	if (!dentry)
-		return ERR_PTR(-ECHILD);
-	error = shmem_getpage(inode, 0, &page, SGP_READ, NULL);
-	if (error)
-		return ERR_PTR(error);
-	unlock_page(page);
+	if (!dentry) {
+		page = find_get_page(inode->i_mapping, 0);
+		if (!page)
+			return ERR_PTR(-ECHILD);
+		if (!PageUptodate(page)) {
+			put_page(page);
+			return ERR_PTR(-ECHILD);
+		}
+	} else {
+		error = shmem_getpage(inode, 0, &page, SGP_READ, NULL);
+		if (error)
+			return ERR_PTR(error);
+		unlock_page(page);
+	}
 	*cookie = page;
 	return page_address(page);
 }