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From: NeilBrown <neilb@suse.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Anna Schumaker <anna.schumaker@netapp.com>
Cc: linux-nfs@vger.kernel.org, Lai Jiangshan <jiangshanlai@gmail.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 1/4] NFS: slight optimization for walking list for delegations
Date: Mon, 30 Apr 2018 14:31:30 +1000	[thread overview]
Message-ID: <152506269054.7246.3941740801391514623.stgit@noble> (raw)
In-Reply-To: <152506256513.7246.13171564155614823841.stgit@noble>

There are 3 places where we walk the list of delegations
for an nfs_client.
In each case there are two nested loops, one for nfs_servers
and one for nfs_delegations.

When we find an interesting delegation we try to get an active
reference to the server.  If that fails, it is pointless to
continue to look at the other delegation for the server as
we will never be able to get an active reference.
So instead of continuing in the inner loop, break out
and continue in the outer loop.
---
 fs/nfs/delegation.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 1819d0d0ba4b..af32365894c8 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -495,7 +495,7 @@ int nfs_client_return_marked_delegations(struct nfs_client *clp)
 			if (!nfs_delegation_need_return(delegation))
 				continue;
 			if (!nfs_sb_active(server->super))
-				continue;
+				break;
 			inode = nfs_delegation_grab_inode(delegation);
 			if (inode == NULL) {
 				rcu_read_unlock();
@@ -887,7 +887,7 @@ void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 						&delegation->flags) == 0)
 				continue;
 			if (!nfs_sb_active(server->super))
-				continue;
+				break;
 			inode = nfs_delegation_grab_inode(delegation);
 			if (inode == NULL) {
 				rcu_read_unlock();
@@ -995,7 +995,7 @@ void nfs_reap_expired_delegations(struct nfs_client *clp)
 						&delegation->flags) == 0)
 				continue;
 			if (!nfs_sb_active(server->super))
-				continue;
+				break;
 			inode = nfs_delegation_grab_inode(delegation);
 			if (inode == NULL) {
 				rcu_read_unlock();

  parent reply	other threads:[~2018-04-30  4:32 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30  4:31 [PATCH 0/4 V2] Avoid quadratic search when freeing delegations NeilBrown
2018-04-30  4:31 ` [PATCH 3/4] rculist: add list_for_each_entry_from_rcu() NeilBrown
2018-04-30  5:20   ` Josh Triplett
2018-04-30 13:43     ` Paul E. McKenney
2018-04-30 15:14       ` Steven Rostedt
2018-04-30 15:35         ` Paul E. McKenney
2018-05-01  3:11           ` [PATCH 3/4 v2] " NeilBrown
2018-05-01 14:14             ` Paul E. McKenney
2018-05-01 21:34               ` NeilBrown
2018-04-30  4:31 ` NeilBrown [this message]
2018-04-30 15:17   ` [PATCH 1/4] NFS: slight optimization for walking list for delegations Steven Rostedt
2018-05-31  5:23     ` [PATCH 1/4 v2] " NeilBrown
2018-06-04 21:31       ` Steven Rostedt
2018-04-30  4:31 ` [PATCH 2/4] NFS: use cond_resched() when restarting walk of delegation list NeilBrown
2018-04-30  4:31 ` [PATCH 4/4] NFS: Avoid quadratic search when freeing delegations NeilBrown

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