Nvm, sync_and_flush forces a sync for non-writeahead journals.
-Sam
On Mon, May 19, 2014 at 1:15 PM, Samuel Just <sam.just@xxxxxxxxxxx> wrote:
> Why would the osd need to create and remove 1 btrfs snapshot per temp directory?
> -Sam
>
> On Sun, May 18, 2014 at 5:47 AM, Alexandre Oliva <oliva@xxxxxxx> wrote:
>> When a btrfs OSD suicides because it couldn't keep up with others
>> (recovery included), it is often the case that the filesystem is in a
>> state in which creating and removing snapshots takes a long time. It
>> is likely that there are going to be plenty of recovering PGs (with
>> corresponding TEMP directories), and we will create and remove a btrfs
>> snapshot for every such directory we remove at startup. This is very
>> wasteful: there's no reason to not pile up as many removals as
>> possible before syncing and flushing the removal so as to force a
>> btrfs snapshot.
>>
>> This patch introduces an optional argument to the function used to
>> remove PGs to control whether or not to perform the final flush. The
>> flush still happens if the call does not pass that argument, but with
>> the patch, the startup removals skip the per-PG flush, and run a
>> single flush at the end.
>>
>> Signed-off-by: Alexandre Oliva <oliva@xxxxxxx>
>> ---
>> src/osd/OSD.cc | 12 +++++++++---
>> src/osd/OSD.h | 3 ++-
>> 2 files changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
>> index 4240ba8..504cb71 100644
>> --- a/src/osd/OSD.cc
>> +++ b/src/osd/OSD.cc
>> @@ -1774,7 +1774,8 @@ int OSD::read_superblock()
>>
>>
>>
>> -void OSD::recursive_remove_collection(ObjectStore *store, coll_t tmp)
>> +void OSD::recursive_remove_collection(ObjectStore *store, coll_t tmp,
>> + bool flush)
>> {
>> OSDriver driver(
>> store,
>> @@ -1810,7 +1811,8 @@ void OSD::recursive_remove_collection(ObjectStore *store, coll_t tmp)
>> t.remove_collection(tmp);
>> int r = store->apply_transaction(t);
>> assert(r == 0);
>> - store->sync_and_flush();
>> + if (flush)
>> + store->sync_and_flush();
>> }
>>
>>
>> @@ -2046,6 +2048,7 @@ void OSD::load_pgs()
>>
>> set<spg_t> head_pgs;
>> map<spg_t, interval_set<snapid_t> > pgs;
>> + bool flush = false;
>> for (vector<coll_t>::iterator it = ls.begin();
>> it != ls.end();
>> ++it) {
>> @@ -2056,7 +2059,8 @@ void OSD::load_pgs()
>> if (it->is_temp(pgid) ||
>> it->is_removal(&seq, &pgid)) {
>> dout(10) << "load_pgs " << *it << " clearing temp" << dendl;
>> - recursive_remove_collection(store, *it);
>> + recursive_remove_collection(store, *it, false);
>> + flush = true;
>> continue;
>> }
>>
>> @@ -2074,6 +2078,8 @@ void OSD::load_pgs()
>>
>> dout(10) << "load_pgs ignoring unrecognized " << *it << dendl;
>> }
>> + if (flush)
>> + store->sync_and_flush();
>>
>> bool has_upgraded = false;
>> for (map<spg_t, interval_set<snapid_t> >::iterator i = pgs.begin();
>> diff --git a/src/osd/OSD.h b/src/osd/OSD.h
>> index ce8b74c..f599e43 100644
>> --- a/src/osd/OSD.h
>> +++ b/src/osd/OSD.h
>> @@ -870,7 +870,8 @@ public:
>> hobject_t oid(sobject_t("infos", CEPH_NOSNAP));
>> return oid;
>> }
>> - static void recursive_remove_collection(ObjectStore *store, coll_t tmp);
>> + static void recursive_remove_collection(ObjectStore *store, coll_t tmp,
>> + bool flush = true);
>>
>> /**
>> * get_osd_initial_compat_set()
>>
>> --
>> Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
>> You must be the change you wish to see in the world. -- Gandhi
>> Be Free! -- http://FSFLA.org/ FSF Latin America board member
>> Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer
>> --
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