NFSv4: Clean up the OPEN/CLOSE serialisation code

Reduce the time spent locking the rpc_sequence structure by queuing the
nfs_seqid only when we are ready to take the lock (when calling
nfs_wait_on_sequence).

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

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 9e2e1c7..a51a753 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3331,15 +3331,12 @@ static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl,
 
        p->arg.fh = NFS_FH(inode);
        p->arg.fl = &p->fl;
-       if (!(lsp->ls_seqid.flags & NFS_SEQID_CONFIRMED)) {
-               p->arg.open_seqid = nfs_alloc_seqid(&lsp->ls_state->owner->so_seqid);
-               if (p->arg.open_seqid == NULL)
-                       goto out_free;
-
-       }
+       p->arg.open_seqid = nfs_alloc_seqid(&lsp->ls_state->owner->so_seqid);
+       if (p->arg.open_seqid == NULL)
+               goto out_free;
        p->arg.lock_seqid = nfs_alloc_seqid(&lsp->ls_seqid);
        if (p->arg.lock_seqid == NULL)
-               goto out_free;
+               goto out_free_seqid;
        p->arg.lock_stateid = &lsp->ls_stateid;
        p->arg.lock_owner.clientid = server->nfs_client->cl_clientid;
        p->arg.lock_owner.id = lsp->ls_id.id;
@@ -3348,9 +3345,9 @@ static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl,
        p->ctx = get_nfs_open_context(ctx);
        memcpy(&p->fl, fl, sizeof(p->fl));
        return p;
+out_free_seqid:
+       nfs_free_seqid(p->arg.open_seqid);
 out_free:
-       if (p->arg.open_seqid != NULL)
-               nfs_free_seqid(p->arg.open_seqid);
        kfree(p);
        return NULL;
 }
@@ -3368,20 +3365,16 @@ static void nfs4_lock_prepare(struct rpc_task *task, void *calldata)
        };
 
        dprintk("%s: begin!\n", __FUNCTION__);
+       if (nfs_wait_on_sequence(data->arg.lock_seqid, task) != 0)
+               return;
        /* Do we need to do an open_to_lock_owner? */
        if (!(data->arg.lock_seqid->sequence->flags & NFS_SEQID_CONFIRMED)) {
                if (nfs_wait_on_sequence(data->arg.open_seqid, task) != 0)
                        return;
                data->arg.open_stateid = &state->stateid;
                data->arg.new_lock_owner = 1;
-               /* Retest in case we raced... */
-               if (!(data->arg.lock_seqid->sequence->flags & NFS_SEQID_CONFIRMED))
-                       goto do_rpc;
-       }
-       if (nfs_wait_on_sequence(data->arg.lock_seqid, task) != 0)
-               return;
-       data->arg.new_lock_owner = 0;
-do_rpc:        
+       } else
+               data->arg.new_lock_owner = 0;
        data->timestamp = jiffies;
        rpc_call_setup(task, &msg, 0);
        dprintk("%s: done!, ret = %d\n", __FUNCTION__, data->rpc_status);
@@ -3419,6 +3412,7 @@ static void nfs4_lock_release(void *calldata)
        struct nfs4_lockdata *data = calldata;
 
        dprintk("%s: begin!\n", __FUNCTION__);
+       nfs_free_seqid(data->arg.open_seqid);
        if (data->cancelled != 0) {
                struct rpc_task *task;
                task = nfs4_do_unlck(&data->fl, data->ctx, data->lsp,
@@ -3428,8 +3422,6 @@ static void nfs4_lock_release(void *calldata)
                dprintk("%s: cancelling lock!\n", __FUNCTION__);
        } else
                nfs_free_seqid(data->arg.lock_seqid);
-       if (data->arg.open_seqid != NULL)
-               nfs_free_seqid(data->arg.open_seqid);
        nfs4_put_lock_state(data->lsp);
        put_nfs_open_context(data->ctx);
        kfree(data);

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 5a39c6f..bf94c6e 100644 (file)
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -644,27 +644,26 @@ void nfs4_copy_stateid(nfs4_stateid *dst, struct nfs4_state *state, fl_owner_t f
 
 struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter)
 {
-       struct rpc_sequence *sequence = counter->sequence;
        struct nfs_seqid *new;
 
        new = kmalloc(sizeof(*new), GFP_KERNEL);
        if (new != NULL) {
                new->sequence = counter;
-               spin_lock(&sequence->lock);
-               list_add_tail(&new->list, &sequence->list);
-               spin_unlock(&sequence->lock);
+               INIT_LIST_HEAD(&new->list);
        }
        return new;
 }
 
 void nfs_free_seqid(struct nfs_seqid *seqid)
 {
-       struct rpc_sequence *sequence = seqid->sequence->sequence;
+       if (!list_empty(&seqid->list)) {
+               struct rpc_sequence *sequence = seqid->sequence->sequence;
 
-       spin_lock(&sequence->lock);
-       list_del(&seqid->list);
-       spin_unlock(&sequence->lock);
-       rpc_wake_up(&sequence->wait);
+               spin_lock(&sequence->lock);
+               list_del(&seqid->list);
+               spin_unlock(&sequence->lock);
+               rpc_wake_up(&sequence->wait);
+       }
        kfree(seqid);
 }
 
@@ -675,6 +674,7 @@ void nfs_free_seqid(struct nfs_seqid *seqid)
  */
 static void nfs_increment_seqid(int status, struct nfs_seqid *seqid)
 {
+       BUG_ON(list_first_entry(&seqid->sequence->sequence->list, struct nfs_seqid, list) != seqid);
        switch (status) {
                case 0:
                        break;
@@ -726,15 +726,15 @@ int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task)
        struct rpc_sequence *sequence = seqid->sequence->sequence;
        int status = 0;
 
-       if (sequence->list.next == &seqid->list)
-               goto out;
        spin_lock(&sequence->lock);
-       if (sequence->list.next != &seqid->list) {
-               rpc_sleep_on(&sequence->wait, task, NULL, NULL);
-               status = -EAGAIN;
-       }
+       if (list_empty(&seqid->list))
+               list_add_tail(&seqid->list, &sequence->list);
+       if (list_first_entry(&sequence->list, struct nfs_seqid, list) == seqid)
+               goto unlock;
+       rpc_sleep_on(&sequence->wait, task, NULL, NULL);
+       status = -EAGAIN;
+unlock:
        spin_unlock(&sequence->lock);
-out:
        return status;
 }