NFSv4.1: If slot allocation fails due to OOM, retry more quickly

If the NFSv4.1 session slot allocation fails due to an ENOMEM condition,
then set the task->tk_timeout to 1/4 second to ensure that we do retry
the slot allocation more quickly.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 0642e28704de..e9e4d6393f1b 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -662,7 +662,7 @@ static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table  *tbl,
                         return slot;
                 p = &slot->next;
         }
-        return NULL;
+        return ERR_PTR(-ENOMEM);
 }
 
 /*
@@ -676,7 +676,7 @@ static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table  *tbl,
  */
 static struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
 {
-        struct nfs4_slot *ret = NULL;
+        struct nfs4_slot *ret = ERR_PTR(-EBUSY);
         u32 slotid;
 
         dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
@@ -686,7 +686,7 @@ static struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
         if (slotid > tbl->max_slotid)
                 goto out;
         ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
-        if (ret == NULL)
+        if (IS_ERR(ret))
                 goto out;
         __set_bit(slotid, tbl->used_slots);
         if (slotid > tbl->highest_used_slotid ||
@@ -698,7 +698,7 @@ static struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
 out:
         dprintk("<-- %s used_slots=%04lx highest_used=%d slotid=%d \n",
                 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
-                ret ? ret->slot_nr : -1);
+                !IS_ERR(ret) ? ret->slot_nr : -1);
         return ret;
 }
 
@@ -727,6 +727,8 @@ int nfs41_setup_sequence(struct nfs4_session *session,
 
         tbl = &session->fc_slot_table;
 
+        task->tk_timeout = 0;
+
         spin_lock(&tbl->slot_tbl_lock);
         if (test_bit(NFS4_SESSION_DRAINING, &session->session_state) &&
             !rpc_task_has_priority(task, RPC_PRIORITY_PRIVILEGED)) {
@@ -746,7 +748,10 @@ int nfs41_setup_sequence(struct nfs4_session *session,
         }
 
         slot = nfs4_alloc_slot(tbl);
-        if (slot == NULL) {
+        if (IS_ERR(slot)) {
+                /* If out of memory, try again in 1/4 second */
+                if (slot == ERR_PTR(-ENOMEM))
+                        task->tk_timeout = HZ >> 2;
                 rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
                 spin_unlock(&tbl->slot_tbl_lock);
                 dprintk("<-- %s: no free slots\n", __func__);
@@ -5778,7 +5783,7 @@ static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
 {
         if (max_reqs <= tbl->max_slots)
                 return 0;
-        if (nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS))
+        if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
                 return 0;
         return -ENOMEM;
 }