From e8e1ba96b207deba1339b09983f8b29f92cb1497 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Fri, 4 Feb 2011 20:45:58 -0800 Subject: [PATCH 1/1] ceph: queue cap_snaps once per realm We were forming a dirty list, and then queueing cap_snaps for each realm _and_ its children, regardless of whether the children were already in the dirty list. This meant we did it twice for some realms. Which in turn meant we corrupted mdsc->snap_flush_list when the cap_snap was re-added to the list it was already on, and could trigger an infinite loop. We were also using recursion to do reach all the children, a no-no when stack is limited. Instead, (re)queue any children on the dirty list, avoiding processing anything twice and avoiding any recursion. Signed-off-by: Sage Weil --- fs/ceph/snap.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 39c243acd062..f40b9139e437 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -584,10 +584,14 @@ static void queue_realm_cap_snaps(struct ceph_snap_realm *realm) if (lastinode) iput(lastinode); - dout("queue_realm_cap_snaps %p %llx children\n", realm, realm->ino); - list_for_each_entry(child, &realm->children, child_item) - queue_realm_cap_snaps(child); + list_for_each_entry(child, &realm->children, child_item) { + dout("queue_realm_cap_snaps %p %llx queue child %p %llx\n", + realm, realm->ino, child, child->ino); + list_del_init(&child->dirty_item); + list_add(&child->dirty_item, &realm->dirty_item); + } + list_del_init(&realm->dirty_item); dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino); } @@ -683,7 +687,9 @@ more: * queue cap snaps _after_ we've built the new snap contexts, * so that i_head_snapc can be set appropriately. */ - list_for_each_entry(realm, &dirty_realms, dirty_item) { + while (!list_empty(&dirty_realms)) { + realm = list_first_entry(&dirty_realms, struct ceph_snap_realm, + dirty_item); queue_realm_cap_snaps(realm); } -- 2.39.2