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authorXue jiufei <xuejiufei@huawei.com>2016-01-14 15:17:18 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-14 16:00:49 -0800
commit30bee898f86506893883ffb8db20d8101a29b5f5 (patch)
treed1998a65a4373824d785773e6a9c2e7b504b01b5 /fs/ocfs2/dlm
parenta84ac334dcb44c76f0b051513a6c27a2d747f883 (diff)
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ocfs2/dlm: fix a race between purge and migration
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. Node A call dlm_mig_lockres_handler to handle this message. dlm_mig_lockres_handler dlm_lookup_lockres >>>>>> race window, dlm_run_purge_list may run and send deref message to master, waiting the response spin_lock(&res->spinlock); res->state |= DLM_LOCK_RES_MIGRATING; spin_unlock(&res->spinlock); dlm_mig_lockres_handler returns >>>>>> dlm_thread receives the response from master for the deref message and triggers the BUG because the lockres has the state DLM_LOCK_RES_MIGRATING with the following message: dlm_purge_lockres:209 ERROR: 6633EB681FA7474A9C280A4E1A836F0F: res M0000000000000000030c0300000000 in use after deref Signed-off-by: Jiufei Xue <xuejiufei@huawei.com> Reviewed-by: Joseph Qi <joseph.qi@huawei.com> Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ocfs2/dlm')
-rw-r--r--fs/ocfs2/dlm/dlmrecovery.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 9e4f862d20fe..86fb53614bf4 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -1373,6 +1373,7 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
char *buf = NULL;
struct dlm_work_item *item = NULL;
struct dlm_lock_resource *res = NULL;
+ unsigned int hash;
if (!dlm_grab(dlm))
return -EINVAL;
@@ -1400,7 +1401,10 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
/* 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. */
- res = dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len);
+ hash = dlm_lockid_hash(mres->lockname, mres->lockname_len);
+ spin_lock(&dlm->spinlock);
+ res = __dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len,
+ hash);
if (res) {
/* this will get a ref on res */
/* mark it as recovering/migrating and hash it */
@@ -1421,13 +1425,16 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
mres->lockname_len, mres->lockname);
ret = -EFAULT;
spin_unlock(&res->spinlock);
+ spin_unlock(&dlm->spinlock);
dlm_lockres_put(res);
goto leave;
}
res->state |= DLM_LOCK_RES_MIGRATING;
}
spin_unlock(&res->spinlock);
+ spin_unlock(&dlm->spinlock);
} else {
+ spin_unlock(&dlm->spinlock);
/* need to allocate, just like if it was
* mastered here normally */
res = dlm_new_lockres(dlm, mres->lockname, mres->lockname_len);