ovl: do not generate duplicate fsnotify events for "fake" path

[ Upstream commit d989903058a83e8536cc7aadf9256a47d5c173fe ]

Overlayfs "fake" path is used for stacked file operations on underlying
files.  Operations on files with "fake" path must not generate fsnotify
events with path data, because those events have already been generated at
overlayfs layer and because the reported event->fd for fanotify marks on
underlying inode/filesystem will have the wrong path (the overlayfs path).

Link: https://lore.kernel.org/linux-fsdevel/20190423065024.12695-1-jencce.kernel@gmail.com/
Reported-by: Murphy Zhou <jencce.kernel@gmail.com>
Fixes: d1d04ef8572b ("ovl: stack file ops")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 0c810f20f778b9e5884fa2524e2bd2128d6b6260..2c993937b784dd4632393a7dcec3b54868ff2a4c 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -29,10 +29,11 @@ static struct file *ovl_open_realfile(const struct file *file,
        struct inode *inode = file_inode(file);
        struct file *realfile;
        const struct cred *old_cred;
+       int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
 
        old_cred = ovl_override_creds(inode->i_sb);
-       realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
-                                      realinode, current_cred());
+       realfile = open_with_fake_path(&file->f_path, flags, realinode,
+                                      current_cred());
        revert_creds(old_cred);
 
        pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
@@ -50,7 +51,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
        int err;
 
        /* No atime modificaton on underlying */
-       flags |= O_NOATIME;
+       flags |= O_NOATIME | FMODE_NONOTIFY;
 
        /* If some flag changed that cannot be changed then something's amiss */
        if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))