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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