[ceph-users] Using sendfile on Ceph FS results in data stuck in client cache

Hi all, Using sendfile function to write data to cephfs, the data doesn't end up being written. From the client that writes the file, it looks correct at first, but from all other ceph clients, the size is 0 bytes. Re-mounting the filesystem, the data is lost. I didn't see any errors, the data just doesn't get written, as if it's just cached in cephfs client. Writing just an extra byte at the end of the file (without sendfile), it seems to trigger the actual write of all the data. Could someone else confirm if they are also seeing such issue? I'm on ceph 13.2.8, using kernel module for mounting on CentOS7. I've used this sendfile-example for the example below: https://github.com/pijewski/sendfile-example/blob/master/sendfile.c Using a small 27 byte source file. # ls -lh examples/ -rw-r--r-- 1 root c3-staff 27 Mar 24 18:04 src # ./sendfile examples/src examples/dst 27 # ls -lh examples/ ------x--- 1 root c3-staff 27 Mar 24 18:12 dst -rw-r--r-- 1 root c3-staff 27 Mar 24 18:04 src But, directory is still on 27 bytes: # ls -lhd examples drwxr-sr-x 1 root c3-staff 27 Mar 24 18:15 examples and on all other cephfs clients, the file is empty: # ls -lh examples/ ------x--- 1 root c3-staff 0 Mar 24 18:12 dst -rw-r--r-- 1 root c3-staff 27 Mar 24 18:04 src Is this a bug in cephfs, or should I not expect sendfile to work (as it is not posix compliant). There are no error reported from what i can see, and it is 100% reproducible Best regards, Mikael