From 388c4bcb4e63e88fb1f312a2f5f9eb2623afcf5b Mon Sep 17 00:00:00 2001 From: Sunil Mushran Date: Fri, 19 Nov 2010 15:06:50 -0800 Subject: ocfs2/dlm: Migrate lockres with no locks if it has a reference o2dlm was not migrating resources with zero locks because it assumed that that resource would get purged by dlm_thread. However, some usage patterns involve creating and dropping locks at a high rate leading to the migrate thread seeing zero locks but the purge thread seeing an active reference. When this happens, the dlm_thread cannot purge the resource and the migrate thread sees no reason to migrate that resource. The spell is broken when the migrate thread catches the resource with a lock. The fix is to make the migrate thread also consider the reference map. This usage pattern can be triggered by userspace on userdlm locks and flocks. Signed-off-by: Sunil Mushran Signed-off-by: Joel Becker --- fs/ocfs2/dlm/dlmmaster.c | 40 +++++++++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 13 deletions(-) (limited to 'fs/ocfs2/dlm') diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c index f564b0e5f80d..59f0f6bdfc62 100644 --- a/fs/ocfs2/dlm/dlmmaster.c +++ b/fs/ocfs2/dlm/dlmmaster.c @@ -2346,7 +2346,8 @@ static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data) */ static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm, struct dlm_lock_resource *res, - int *numlocks) + int *numlocks, + int *hasrefs) { int ret; int i; @@ -2356,6 +2357,9 @@ static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm, assert_spin_locked(&res->spinlock); + *numlocks = 0; + *hasrefs = 0; + ret = -EINVAL; if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) { mlog(0, "cannot migrate lockres with unknown owner!\n"); @@ -2386,7 +2390,13 @@ static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm, } *numlocks = count; - mlog(0, "migrateable lockres having %d locks\n", *numlocks); + + count = find_next_bit(res->refmap, O2NM_MAX_NODES, 0); + if (count < O2NM_MAX_NODES) + *hasrefs = 1; + + mlog(0, "%s: res %.*s, Migrateable, locks %d, refs %d\n", dlm->name, + res->lockname.len, res->lockname.name, *numlocks, *hasrefs); leave: return ret; @@ -2408,7 +2418,7 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm, const char *name; unsigned int namelen; int mle_added = 0; - int numlocks; + int numlocks, hasrefs; int wake = 0; if (!dlm_grab(dlm)) @@ -2417,13 +2427,13 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm, name = res->lockname.name; namelen = res->lockname.len; - mlog(0, "migrating %.*s to %u\n", namelen, name, target); + mlog(0, "%s: Migrating %.*s to %u\n", dlm->name, namelen, name, target); /* * ensure this lockres is a proper candidate for migration */ spin_lock(&res->spinlock); - ret = dlm_is_lockres_migrateable(dlm, res, &numlocks); + ret = dlm_is_lockres_migrateable(dlm, res, &numlocks, &hasrefs); if (ret < 0) { spin_unlock(&res->spinlock); goto leave; @@ -2431,10 +2441,8 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm, spin_unlock(&res->spinlock); /* no work to do */ - if (numlocks == 0) { - mlog(0, "no locks were found on this lockres! done!\n"); + if (numlocks == 0 && !hasrefs) goto leave; - } /* * preallocate up front @@ -2459,14 +2467,14 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm, * find a node to migrate the lockres to */ - mlog(0, "picking a migration node\n"); spin_lock(&dlm->spinlock); /* pick a new node */ if (!test_bit(target, dlm->domain_map) || target >= O2NM_MAX_NODES) { target = dlm_pick_migration_target(dlm, res); } - mlog(0, "node %u chosen for migration\n", target); + mlog(0, "%s: res %.*s, Node %u chosen for migration\n", dlm->name, + namelen, name, target); if (target >= O2NM_MAX_NODES || !test_bit(target, dlm->domain_map)) { @@ -2667,7 +2675,7 @@ int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res) { int ret; int lock_dropped = 0; - int numlocks; + int numlocks, hasrefs; spin_lock(&res->spinlock); if (res->owner != dlm->node_num) { @@ -2681,8 +2689,8 @@ int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res) } /* No need to migrate a lockres having no locks */ - ret = dlm_is_lockres_migrateable(dlm, res, &numlocks); - if (ret >= 0 && numlocks == 0) { + ret = dlm_is_lockres_migrateable(dlm, res, &numlocks, &hasrefs); + if (ret >= 0 && numlocks == 0 && !hasrefs) { spin_unlock(&res->spinlock); goto leave; } @@ -2915,6 +2923,12 @@ static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm, } queue++; } + + nodenum = find_next_bit(res->refmap, O2NM_MAX_NODES, 0); + if (nodenum < O2NM_MAX_NODES) { + spin_unlock(&res->spinlock); + return nodenum; + } spin_unlock(&res->spinlock); mlog(0, "have not found a suitable target yet! checking domain map\n"); -- cgit v1.2.3