Hi Maintainers:

This is one very important bug fixing patch needed to be backported for ceph.

I have attached the patches based one the latest branches[1] of 4.9.y, 4.14.y, 4.19.y, 5.4.y, 5.10.y, 5.15.y and 5.19.y.

This patch is simple and the conflict is trivial.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Thanks!

- Xiubo

On 12/10/2022 09:51, Xiubo Li wrote:

Hi Maitainers

This patch is a fix in kceph module and should be backported to any affected stable old kernels. And the original patch missed tagging stable and got merged already months ago:

commit 7cb9994754f8a36ae9e5ec4597c5c4c2d6c03832 Author: Hu Weiwen sehuww@mail.scut.edu.cn Date:   Fri Jul 1 10:52:27 2022 +0800

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

Just a single patch.

I am not very sure this is the correct way to do this, if anything else I need to do to backport this to old kernels please let me know.

Thanks!

• Xiubo

On 01/07/2022 10:52, Hu Weiwen wrote:

...

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

---

rebased onto ceph_client repo testing branch

fs/ceph/file.c | 9 ++++++---   1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 296fd1c7ece8..289e66e9cbb0 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -745,6 +745,11 @@ 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;     retry:       if (flags & O_CREAT) { @@ -836,9 +841,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,       set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);       req->r_new_inode = new_inode;       new_inode = NULL; -    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)) {