From: Jonathan Davies Date: Wed, 11 Nov 2015 11:21:53 +0000 (+0000) Subject: oxenstored: Quota.merge: don't assume domain already exists X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=82ff7cbed64e3cc094d6812b3ad672c660649969;p=people%2Fjulieng%2Fxen-unstable.git oxenstored: Quota.merge: don't assume domain already exists In Quota.merge, we merge two quota hashtables, orig_quota and mod_quota, putting the results into dest_quota. These hashtables map domids to the number of entries currently owned by that domain. When mod_quota contains an entry for a domid that was not present in orig_quota (or dest_quota), the call to get_entry caused Quota.merge to raise a Not_found exception. This propagates back to the client as an ENOENT error, which is not an appropriate return value from some operations, such as transaction_end. This situation can arise when a transaction that introduces a domain (hence calling Quota.add_entry) needs to be coalesced due to concurrent xenstore activity. This patch handles the merge in the case where mod_quota contains an entry not present in orig_quota (or in dest_quota) by treating that hashtable as having existing value 0. Signed-off-by: Jonathan Davies Acked-by: Ian Jackson --- diff --git a/tools/ocaml/xenstored/quota.ml b/tools/ocaml/xenstored/quota.ml index e6953c63f1..abcac91280 100644 --- a/tools/ocaml/xenstored/quota.ml +++ b/tools/ocaml/xenstored/quota.ml @@ -83,6 +83,6 @@ let add quota diff = Hashtbl.iter (fun id nb -> set_entry quota id (get_entry quota id + nb)) diff.cur let merge orig_quota mod_quota dest_quota = - Hashtbl.iter (fun id nb -> let diff = nb - (get_entry orig_quota id) in + Hashtbl.iter (fun id nb -> let diff = nb - (try get_entry orig_quota id with Not_found -> 0) in if diff <> 0 then - set_entry dest_quota id ((get_entry dest_quota id) + diff)) mod_quota.cur + set_entry dest_quota id ((try get_entry dest_quota id with Not_found -> 0) + diff)) mod_quota.cur