init: add an init_eaccess helper

Add a simple helper to check if a file exists based on kernel space file
name and switch the early init code over to it.  Note that this
theoretically changes behavior as it always is based on the effective
permissions.  But during early init that doesn't make a difference.

Signed-off-by: Christoph Hellwig <hch@lst.de>

2 files changed, 14 insertions, 1 deletions

diff --git a/fs/init.c b/fs/init.c
index a66032d128b6..6d9af40d2897 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -109,6 +109,19 @@ int __init init_chmod(const char *filename, umode_t mode)
 	return error;
 }
 
+int __init init_eaccess(const char *filename)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, LOOKUP_FOLLOW, &path);
+	if (error)
+		return error;
+	error = inode_permission(d_inode(path.dentry), MAY_ACCESS);
+	path_put(&path);
+	return error;
+}
+
 int __init init_unlink(const char *pathname)
 {
 	return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
diff --git a/fs/open.c b/fs/open.c
index 7ba89eae46c5..aafecd1f7ba1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -394,7 +394,7 @@ static const struct cred *access_override_creds(void)
 	return old_cred;
 }
 
-long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
+static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
 {
 	struct path path;
 	struct inode *inode;