Hi Mike, Returning to the OSD cmpext functionality in https://github.com/ceph/ceph/pull/8911 , I'm wondering how such requests should be handled against unwritten ranges. Currently an OSD will return -EINVAL to the client, as the short read will be caught via: https://github.com/ceph/ceph/pull/8911/commits/440895ea9f2604756c9f3c81e5c4ec5ca40401d7#diff-72747d40a424e7b5404366b557ff12a3R3722 -EINVAL then means that krbd will return an error for the corresponding client I/O. For read requests, rbd_img_obj_request_read_callback() handles zero-filling read buffers that cover unwritten RBD ranges. For SCSI Compare And Write the OSD is responsible for atomicity, so zero-filling on the client side is problematic. One potential option could be to add a truncate/zero operation to the Compare And Write compound request, or optionally support truncate_seq and truncate_size parameters in cmpext. Any thoughts/suggestions on the approach here? FWIW, I'm using the following test to trigger this from the client side: https://github.com/sahlberg/libiscsi/pull/213/commits/e6f2ce306cf8706b666ec088fc74219bc52ea8cf Cheers, David -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
