Patch "ovl: fix failure to fsync lower dir" has been added to the 4.15-stable tree

Patch "ovl: fix failure to fsync lower dir" has been added to the 4.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ovl: fix failure to fsync lower dir

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ovl-fix-failure-to-fsync-lower-dir.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d796e77f1dd541fe34481af2eee6454688d13982 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Wed, 8 Nov 2017 09:39:46 +0200
Subject: ovl: fix failure to fsync lower dir
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Amir Goldstein <amir73il@gmail.com>

commit d796e77f1dd541fe34481af2eee6454688d13982 upstream.

As a writable mount, it is not expected for overlayfs to return
EINVAL/EROFS for fsync, even if dir/file is not changed.

This commit fixes the case of fsync of directory, which is easier to
address, because overlayfs already implements fsync file operation for
directories.

The problem reported by Raphael is that new PostgreSQL 10.0 with a
database in overlayfs where lower layer in squashfs fails to start.
The failure is due to fsync error, when PostgreSQL does fsync on all
existing db directories on startup and a specific directory exists
lower layer with no changes.

Reported-by: Raphael Hertzog <raphael@ouaza.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Tested-by: Raphaël Hertzog <hertzog@debian.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/overlayfs/readdir.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -769,10 +769,14 @@ static int ovl_dir_fsync(struct file *fi
 	struct dentry *dentry = file->f_path.dentry;
 	struct file *realfile = od->realfile;
 
+	/* Nothing to sync for lower */
+	if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
+		return 0;
+
 	/*
 	 * Need to check if we started out being a lower dir, but got copied up
 	 */
-	if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) {
+	if (!od->is_upper) {
 		struct inode *inode = file_inode(file);
 
 		realfile = READ_ONCE(od->upperfile);


Patches currently in stable-queue which might be from amir73il@gmail.com are

queue-4.15/ovl-take-mnt_want_write-for-removing-impure-xattr.patch
queue-4.15/ovl-take-mnt_want_write-for-work-index-dir-setup.patch
queue-4.15/ovl-hash-directory-inodes-for-fsnotify.patch
queue-4.15/ovl-force-r-o-mount-when-index-dir-creation-fails.patch
queue-4.15/ovl-fix-failure-to-fsync-lower-dir.patch