LU-2272 statahead: ll_intent_drop_lock() called in spinlock

ll_intent_drop_lock() may sleep, which should not be called inside
spinlock.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: Ife50396dc16beaad921751b4bdd7da721dfc15c9
Reviewed-on: http://review.whamcloud.com/9665
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/llite/statahead.c b/lustre/llite/statahead.c
index 45bfe84..2874589 100644 (file)
--- a/lustre/llite/statahead.c
+++ b/lustre/llite/statahead.c
@@ -659,6 +659,7 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
        struct ll_inode_info *lli = ll_i2info(dir);
        struct ll_statahead_info *sai = lli->lli_sai;
        struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
+       __u64 handle = 0;
        bool wakeup;
        ENTRY;
 
@@ -674,6 +675,19 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
        CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
               entry->se_qstr.len, entry->se_qstr.name, rc);
 
+       if (rc != 0) {
+               ll_intent_release(it);
+               iput(dir);
+               OBD_FREE_PTR(minfo);
+       } else {
+               /* release ibits lock ASAP to avoid deadlock when statahead
+                * thread enqueues lock on parent in readdir and another
+                * process enqueues lock on child with parent lock held, eg.
+                * unlink. */
+               handle = it->d.lustre.it_lock_handle;
+               ll_intent_drop_lock(it);
+       }
+
        spin_lock(&lli->lli_sa_lock);
        if (rc != 0) {
                wakeup = __sa_make_ready(sai, entry, rc);
@@ -684,8 +698,7 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
                 * when statahead thread tries to enqueue lock on parent
                 * for readpage and other tries to enqueue lock on child
                 * with parent's lock held, for example: unlink. */
-               entry->se_handle = it->d.lustre.it_lock_handle;
-               ll_intent_drop_lock(it);
+               entry->se_handle = handle;
                wakeup = !sa_has_callback(sai);
                list_add_tail(&entry->se_list, &sai->sai_interim_entries);
        }
@@ -694,11 +707,6 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
                wake_up(&sai->sai_thread.t_ctl_waitq);
        spin_unlock(&lli->lli_sa_lock);
 
-       if (rc != 0) {
-               ll_intent_release(it);
-               iput(dir);
-               OBD_FREE_PTR(minfo);
-       }
        RETURN(rc);
 }