Re: [PATCH] ceph: don't truncate file in atomic_open

[Xiubo Li <xiubli@redhat.com>]

On 6/30/22 10:00 AM, 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>
> ---
>   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 da59e836a06e..a5ecb97b6f41 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -757,6 +757,11 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
>   		/* If it's not being looked up, it's negative */
>   		return -ENOENT;
>   	}
> +	/*
> +	 * 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:
>   	/* do the open */
>   	req = prepare_open_request(dir->i_sb, flags, mode);
> @@ -807,9 +812,7 @@ 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)) {
> --
> 2.25.1
>
Merged into the testing branch. Thanks Weiwen!

-- Xiubo