ceph: don't truncate file in atomic_open

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 5.10 backport]
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 1f873034f46913c2e33f1693972eb16d65e25bee..ddfa6ce3a0fb32753db4ed116d9ba965380e4316 100644 (file)
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -381,6 +381,12 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
        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) {
                err = ceph_pre_init_acls(dir, &mode, &acls);
                if (err < 0)
@@ -411,9 +417,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 
        req->r_parent = dir;
        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);
        err = ceph_handle_snapdir(req, dentry, err);
        if (err)
                goto out_req;