From: Lai Siyao <lai.siyao@intel.com>
Date: Sun, 19 Oct 2014 16:19:21 +0000 (-0400)
Subject: LU-2272 statahead: ll_intent_drop_lock() called in spinlock
X-Git-Tag: 2.6.90~36
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=30165c4024f8a1ee316fb192005d9b2a8b89d0b8;p=fs%2Flustre-release.git

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
--- 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);
 }