[PATCH 5.10 05/54] ceph: dont truncate file in atomic_open

Greg Kroah-Hartman
2022-10-13T18:12:02Z

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 5.10 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
@@ -703,6 +703,12 @@ 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;
@@ -769,9 +775,7 @@ 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);
err = ceph_handle_snapdir(req, dentry, err);
if (err)
goto out_req;