ovl: fix unneeded call to ovl_change_flags()

commit 81a33c1ee941c3bb9ffc6bac8f676be13351344e upstream.

The check if user has changed the overlay file was wrong, causing unneeded
call to ovl_change_flags() including taking f_lock on every file access.

Fixes: d989903058a8 ("ovl: do not generate duplicate fsnotify events for "fake" path")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 15e4fa288475bc34a11f1db63074655babe389bc..7a08a576f7b291c0f73837ffe3ec9c4bf0c3cca6 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -21,13 +21,16 @@ static char ovl_whatisit(struct inode *inode, struct inode *realinode)
                return 'm';
 }
 
+/* No atime modificaton nor notify on underlying */
+#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
+
 static struct file *ovl_open_realfile(const struct file *file,
                                      struct inode *realinode)
 {
        struct inode *inode = file_inode(file);
        struct file *realfile;
        const struct cred *old_cred;
-       int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
+       int flags = file->f_flags | OVL_OPEN_FLAGS;
 
        old_cred = ovl_override_creds(inode->i_sb);
        realfile = open_with_fake_path(&file->f_path, flags, realinode,
@@ -48,8 +51,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
        struct inode *inode = file_inode(file);
        int err;
 
-       /* No atime modificaton on underlying */
-       flags |= O_NOATIME | FMODE_NONOTIFY;
+       flags |= OVL_OPEN_FLAGS;
 
        /* If some flag changed that cannot be changed then something's amiss */
        if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
@@ -102,7 +104,7 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
        }
 
        /* Did the flags change since open? */
-       if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
+       if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
                return ovl_change_flags(real->file, file->f_flags);
 
        return 0;