The patch titled
Subject: ocfs2/dlm: fix a race between purge and migratio
has been added to the -mm tree. Its filename is
ocfs2-dlm-fix-a-race-between-purge-and-migratio.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-dlm-fix-a-race-between-purge-and-migratio.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-dlm-fix-a-race-between-purge-and-migratio.patch
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------------------------------------------------------
From: Xue jiufei <xuejiufei@xxxxxxxxxx>
Subject: ocfs2/dlm: fix a race between purge and migratio
We found a race between purge and migration when doing code review. Node
A put lockres to purgelist before receiving the migrate message from node
B which is the master. dlm_mig_lockres_handler finds the lockres and
releases the dlm spinlock. Then dlm_thread on node A can purge the
lockres. dlm_mig_lockres_handler then gets the lockres spinlock and sends
assert master message to tell other nodes that node A is the master now
even lockres is purged. If node C set the master to node A, and another
node D master the lockres because no node respond he is the master. That
will make node C crash when node D send assert master to node C. So check
if lockres gets unhashed in dlm_mig_lockres_handler to fix this race.
Signed-off-by: Jiufei Xue <xuejiufei@xxxxxxxxxx>
Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxx>
Reviewed-by: Yiwen Jiang <jiangyiwen@xxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/dlm/dlmrecovery.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff -puN fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-fix-a-race-between-purge-and-migratio fs/ocfs2/dlm/dlmrecovery.c
--- a/fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-fix-a-race-between-purge-and-migratio
+++ a/fs/ocfs2/dlm/dlmrecovery.c
@@ -1400,11 +1400,33 @@ int dlm_mig_lockres_handler(struct o2net
/* lookup the lock to see if we have a secondary queue for this
* already... just add the locks in and this will have its owner
* and RECOVERY flag changed when it completes. */
+way_up_top:
res = dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len);
if (res) {
/* this will get a ref on res */
/* mark it as recovering/migrating and hash it */
spin_lock(&res->spinlock);
+
+ /*
+ * Right after dlm spinlock was released, dlm_thread could have
+ * purged the lockres. Check if lockres got unhashed. If so
+ * start over.
+ */
+ if (hlist_unhashed(&res->hash_node)) {
+ spin_unlock(&res->spinlock);
+ dlm_lockres_put(res);
+ goto way_up_top;
+ }
+
+ /* Wait on the resource purge to complete before continuing */
+ if (res->state & DLM_LOCK_RES_DROPPING_REF) {
+ __dlm_wait_on_lockres_flags(res,
+ DLM_LOCK_RES_DROPPING_REF);
+ spin_unlock(&res->spinlock);
+ dlm_lockres_put(res);
+ goto way_up_top;
+ }
+
if (mres->flags & DLM_MRES_RECOVERY) {
res->state |= DLM_LOCK_RES_RECOVERING;
} else {
_
Patches currently in -mm which might be from xuejiufei@xxxxxxxxxx are
ocfs2-dlm-fix-a-race-between-purge-and-migratio.patch
ocfs2-extend-transaction-for-ocfs2_remove_rightmost_path-and-ocfs2_update_edge_lengths-before-to-avoid-inconsistency-between-inode-and-et.patch
extend-enough-credits-for-freeing-one-truncate-record-while-replaying-truncate-records.patch
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