FAILED: patch "[PATCH] ceph: don't truncate file in atomic_open" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7cb9994754f8a36ae9e5ec4597c5c4c2d6c03832 Mon Sep 17 00:00:00 2001
From: Hu Weiwen <sehuww@mail.scut.edu.cn>
Date: Fri, 1 Jul 2022 10:52:27 +0800
Subject: [PATCH] ceph: don't truncate file in atomic_open

Clear O_TRUNC from the flags sent in the MDS create request.

`atomic_open' is called before permission check. We should not do any
modification to the file here. The caller will do the truncation
afterward.

Fixes: 124e68e74099 ("ceph: file operations")
Signed-off-by: Hu Weiwen <sehuww@mail.scut.edu.cn>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index cd025ff25bf0..b4e978420802 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -749,6 +749,11 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	err = ceph_wait_on_conflict_unlink(dentry);
 	if (err)
 		return err;
+	/*
+	 * Do not truncate the file, since atomic_open is called before the
+	 * permission check. The caller will do the truncation afterward.
+	 */
+	flags &= ~O_TRUNC;
 
 	if (flags & O_CREAT) {
 		if (ceph_quota_is_max_files_exceeded(dir))
@@ -824,9 +829,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	}
 
 	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
-	err = ceph_mdsc_do_request(mdsc,
-				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,
-				   req);
+	err = ceph_mdsc_do_request(mdsc, (flags & O_CREAT) ? dir : NULL, req);
 	if (err == -ENOENT) {
 		dentry = ceph_handle_snapdir(req, dentry);
 		if (IS_ERR(dentry)) {