--- /dev/null
+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: ceph: don't truncate file in atomic_open
+
+From: Hu Weiwen <sehuww@mail.scut.edu.cn>
+
+commit 7cb9994754f8a36ae9e5ec4597c5c4c2d6c03832 upstream.
+
+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>
+[Xiubo: fixed a trivial conflict for 5.19 backport]
+Signed-off-by: Xiubo Li <xiubli@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/ceph/file.c | 10 +++++++---
+ 1 file changed, 7 insertions(+), 3 deletions(-)
+
+--- a/fs/ceph/file.c
++++ b/fs/ceph/file.c
+@@ -740,6 +740,12 @@ int ceph_atomic_open(struct inode *dir,
+ if (dentry->d_name.len > NAME_MAX)
+ return -ENAMETOOLONG;
+
++ /*
++ * 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))
+ return -EDQUOT;
+@@ -807,9 +813,7 @@ retry:
+ }
+
+ 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)) {