On Tue, 2012-10-09 at 17:20 -0400, andros@xxxxxxxxxx wrote:
> From: Andy Adamson <andros@xxxxxxxxxx>
>
> There is no advantage to waking up all rpc tasks on each data server disconnect
> or invalid layout error.
>
> For DS disconnect errors where the data server is reseting all I/O to the MDS,
> tasks wakened from the fore channel slot table waitq are immediately reset
> to use the MDS session, and do not request a data server session slot, and
> so do not call nfs41_session_free_slot, and do not wake up the next task on
> the data server session fore channel slot table wait queue.
>
> Replace the call to rpc_wake_up which wakes up all tasks with a call to
> rpc_wake_up_first in the filelayout I/O prepare routines for the case where
> I/O is redirected to the MDS.
>
> Share code with nfs4_check_drain_fc_complete.
This will still have false positive wakeups, though, since there is no
connection to number of slots that are available.
How about rather just letting the session code drive the wakeups? I'm
thinking something like the following patch:
8<--------------------------------------------------------------
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index a525fde..df2474b 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -248,6 +248,7 @@ extern int nfs4_setup_sequence(const struct nfs_server *server,
extern int nfs41_setup_sequence(struct nfs4_session *session,
struct nfs4_sequence_args *args, struct nfs4_sequence_res *res,
struct rpc_task *task);
+extern void nfs41_sequence_free_slot(struct nfs4_sequence_res *res);
extern void nfs4_destroy_session(struct nfs4_session *session);
extern struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp);
extern int nfs4_proc_create_session(struct nfs_client *, struct rpc_cred *);
diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 52d8472..80aa19a 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -291,19 +291,20 @@ static void filelayout_read_prepare(struct rpc_task *task, void *data)
{
struct nfs_read_data *rdata = data;
+ if (nfs41_setup_sequence(rdata->ds_clp->cl_session,
+ &rdata->args.seq_args, &rdata->res.seq_res,
+ task))
+ return;
+
if (filelayout_reset_to_mds(rdata->header->lseg)) {
dprintk("%s task %u reset io to MDS\n", __func__, task->tk_pid);
filelayout_reset_read(rdata);
+ nfs41_sequence_free_slot(&rdata->res.seq_res);
rpc_exit(task, 0);
return;
}
rdata->read_done_cb = filelayout_read_done_cb;
- if (nfs41_setup_sequence(rdata->ds_clp->cl_session,
- &rdata->args.seq_args, &rdata->res.seq_res,
- task))
- return;
-
rpc_call_start(task);
}
@@ -393,17 +394,18 @@ static void filelayout_write_prepare(struct rpc_task *task, void *data)
{
struct nfs_write_data *wdata = data;
+ if (nfs41_setup_sequence(wdata->ds_clp->cl_session,
+ &wdata->args.seq_args, &wdata->res.seq_res,
+ task))
+ return;
+
if (filelayout_reset_to_mds(wdata->header->lseg)) {
dprintk("%s task %u reset io to MDS\n", __func__, task->tk_pid);
filelayout_reset_write(wdata);
+ nfs41_sequence_free_slot(&rdata->res.seq_res);
rpc_exit(task, 0);
return;
}
- if (nfs41_setup_sequence(wdata->ds_clp->cl_session,
- &wdata->args.seq_args, &wdata->res.seq_res,
- task))
- return;
-
rpc_call_start(task);
}
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 68b21d8..d186be2 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -468,7 +468,7 @@ void nfs4_check_drain_bc_complete(struct nfs4_session *ses)
complete(&ses->bc_slot_table.complete);
}
-static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
+void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
{
struct nfs4_slot_table *tbl;
@@ -486,6 +486,7 @@ static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
spin_unlock(&tbl->slot_tbl_lock);
res->sr_slot = NULL;
}
+EXPORT_SYMBOL_GPL(nfs41_sequence_free_slot);
static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *res)
{
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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