diff options
| author | Junxiao Bi | 2015-05-05 16:24:02 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2015-05-05 17:10:11 -0700 |
| commit | b1432a2a35565f538586774a03bf277c27fc267d (patch) | |
| tree | fb75af1bd5c0e4c91b7bb114ca31880ecfbfc0d6 /fs | |
| parent | d8fd150fe3935e1692bf57c66691e17409ebb9c1 (diff) | |
ocfs2: dlm: fix race between purge and get lock resource
There is a race window in dlm_get_lock_resource(), which may return a
lock resource which has been purged. This will cause the process to
hang forever in dlmlock() as the ast msg can't be handled due to its
lock resource not existing.
dlm_get_lock_resource {
...
spin_lock(&dlm->spinlock);
tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
if (tmpres) {
spin_unlock(&dlm->spinlock);
>>>>>>>> race window, dlm_run_purge_list() may run and purge
the lock resource
spin_lock(&tmpres->spinlock);
...
spin_unlock(&tmpres->spinlock);
}
}
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ocfs2/dlm/dlmmaster.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c index a6944b25fd5b..fdf4b41d0609 100644 --- a/fs/ocfs2/dlm/dlmmaster.c +++ b/fs/ocfs2/dlm/dlmmaster.c @@ -757,6 +757,19 @@ lookup: if (tmpres) { spin_unlock(&dlm->spinlock); spin_lock(&tmpres->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(&tmpres->hash_node)) { + spin_unlock(&tmpres->spinlock); + dlm_lockres_put(tmpres); + tmpres = NULL; + goto lookup; + } + /* Wait on the thread that is mastering the resource */ if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) { __dlm_wait_on_lockres(tmpres); |