Re: [PATCH 4/4] fix: release unused ceph cap reservation on readdir error

Hi Slava,

Sorry for the confusing [PATCH 4/4] subject — that was my mistake, not an intentional ceph patch series.

What happened: I batched four unrelated commits into one git send-email range. format-patch numbered them 1/4 through 4/4, but get_maintainer.pl routed each patch only to its subsystem list. ceph-devel received only patch 4.

This is a standalone one-patch fix for ceph. I have resent it as [PATCH 1/1] to ceph-devel in a separate thread.

The bug: in ceph_readdir_prepopulate(), ceph_fill_inode() consumes caps from req->r_caps_reservation. On error paths, unused caps were not returned to the MDS client pool (there is a FIXME: "release caps/leases if error occurs"). On success, ceph_unreserve_caps() is called in mds_client.c; on error it was skipped. The fix calls ceph_unreserve_caps() at out: when err != 0.

How I found it: code review while reading fs/ceph/inode.c — not a live Ceph cluster repro. Compiled fs/ceph/inode.o locally.

Thanks,
Deepak Rao Gaikwad