staging: lustre: 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>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2272
Reviewed-on: http://review.whamcloud.com/9665
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/llite/statahead.c b/drivers/staging/lustre/lustre/llite/statahead.c
index 0d87dc9..92972d0 100644 (file)
--- a/drivers/staging/lustre/lustre/llite/statahead.c
+++ b/drivers/staging/lustre/lustre/llite/statahead.c
@@ -661,6 +661,7 @@ 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;
 
        if (it_disposition(it, DISP_LOOKUP_NEG))
@@ -677,6 +678,21 @@ 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) {
+               ll_intent_release(it);
+               iput(dir);
+               kfree(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->it_lock_handle;
+               ll_intent_drop_lock(it);
+       }
+
        spin_lock(&lli->lli_sa_lock);
        if (rc) {
                wakeup = __sa_make_ready(sai, entry, rc);
@@ -689,8 +705,7 @@ static int ll_statahead_interpret(struct ptlrpc_request *req,
                 * for readpage and other tries to enqueue lock on child
                 * with parent's lock held, for example: unlink.
                 */
-               entry->se_handle = it->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);
        }
@@ -700,11 +715,6 @@ 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) {
-               ll_intent_release(it);
-               iput(dir);
-               kfree(minfo);
-       }
        return rc;
 }