ceph: fix cap ref leak via netfs init_request
Log recovered from a user's cluster:
<7>[ 5413.970692] ceph: get_cap_refs
00000000958c114b ret 1 got Fr
<7>[ 5413.970695] ceph: start_read
00000000958c114b, no cache cap
...
<7>[ 5473.934609] ceph: my wanted = Fr, used = Fr, dirty -
<7>[ 5473.934616] ceph: revocation: pAsLsXsFr -> pAsLsXs (revoking Fr)
<7>[ 5473.934632] ceph: __ceph_caps_issued
00000000958c114b cap
00000000f7784259 issued pAsLsXs
<7>[ 5473.934638] ceph: check_caps
10000000e68.
fffffffffffffffe file_want - used Fr dirty - flushing - issued pAsLsXs revoking Fr retain pAsLsXsFsr AUTHONLY NOINVAL FLUSH_FORCE
The MDS subsequently complains that the kernel client is late releasing
caps.
Approximately, a series of changes to this code by commits
49870056005c
("ceph: convert ceph_readpages to ceph_readahead"),
2de160417315
("netfs: Change ->init_request() to return an error code") and
a5c9dc445139 ("ceph: Make ceph_init_request() check caps on readahead")
resulted in subtle resource cleanup to be missed. The main culprit is
the change in error handling in
2de160417315 which meant that a failure
in init_request() would no longer cause cleanup to be called. That
would prevent the ceph_put_cap_refs() call which would cleanup the
leaked cap ref.
Cc: stable@vger.kernel.org
Fixes: a5c9dc445139 ("ceph: Make ceph_init_request() check caps on readahead")
Link: https://tracker.ceph.com/issues/67008
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>