The patch below does not apply to the 4.14-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)) {