[PATCH v4 04/17] vfs: fix readlinkat to retry on ESTALE

[Jeff Layton <jlayton@redhat.com>]

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/stat.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/stat.c b/fs/stat.c
index 5afeb37..c9d88f7 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -307,14 +307,25 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 	struct path path;
 	int error;
 	int empty = 0;
+	char *name;
+	unsigned int try = 0;
+	unsigned int lookup_flags = LOOKUP_EMPTY;
 
 	if (bufsiz <= 0)
 		return -EINVAL;
 
-	error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
-	if (!error) {
-		struct inode *inode = path.dentry->d_inode;
+	name = getname_flags(pathname, lookup_flags, &empty);
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	do {
+		struct inode *inode;
+
+		error = kern_path_at(dfd, name, lookup_flags, &path);
+		if (error)
+			break;
 
+		inode = path.dentry->d_inode;
 		error = empty ? -ENOENT : -EINVAL;
 		if (inode->i_op->readlink) {
 			error = security_inode_readlink(path.dentry);
@@ -325,7 +336,9 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 			}
 		}
 		path_put(&path);
-	}
+		lookup_flags |= LOOKUP_REVAL;
+	} while (retry_estale(error, try++));
+	putname(name);
 	return error;
 }
 
-- 
1.7.11.2