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From: David Howells <dhowells@redhat.com>
To: Marc Dionne <marc.dionne@auristor.com>
cc: dhowells@redhat.com, linux-afs@lists.infradead.org,
    linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] afs: Don't cache preferred address
Precedence: bulk
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Content-ID: <159568.1709239291.1@warthog.procyon.org.uk>
Date: Thu, 29 Feb 2024 20:41:31 +0000
Message-ID: <159569.1709239291@warthog.procyon.org.uk>

In the AFS fileserver rotation algorithm, don't cache the preferred address
for the server as that will override the explicit preference if a
non-preferred address responds first.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
---
 fs/afs/rotate.c |   21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 700a27bc8c25..ed04bd1eeae8 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -602,6 +602,8 @@ bool afs_select_fileserver(struct afs_operation *op)
 		goto wait_for_more_probe_results;
 
 	alist = op->estate->addresses;
+	best_prio = -1;
+	addr_index = 0;
 	for (i = 0; i < alist->nr_addrs; i++) {
 		if (alist->addrs[i].prio > best_prio) {
 			addr_index = i;
@@ -609,9 +611,7 @@ bool afs_select_fileserver(struct afs_operation *op)
 		}
 	}
 
-	addr_index = READ_ONCE(alist->preferred);
-	if (!test_bit(addr_index, &set))
-		addr_index = __ffs(set);
+	alist->preferred = addr_index;
 
 	op->addr_index = addr_index;
 	set_bit(addr_index, &op->addr_tried);
@@ -656,12 +656,6 @@ bool afs_select_fileserver(struct afs_operation *op)
 next_server:
 	trace_afs_rotate(op, afs_rotate_trace_next_server, 0);
 	_debug("next");
-	ASSERT(op->estate);
-	alist = op->estate->addresses;
-	if (op->call_responded &&
-	    op->addr_index != READ_ONCE(alist->preferred) &&
-	    test_bit(alist->preferred, &op->addr_tried))
-		WRITE_ONCE(alist->preferred, op->addr_index);
 	op->estate = NULL;
 	goto pick_server;
 
@@ -690,14 +684,7 @@ bool afs_select_fileserver(struct afs_operation *op)
 failed:
 	trace_afs_rotate(op, afs_rotate_trace_failed, 0);
 	op->flags |= AFS_OPERATION_STOP;
-	if (op->estate) {
-		alist = op->estate->addresses;
-		if (op->call_responded &&
-		    op->addr_index != READ_ONCE(alist->preferred) &&
-		    test_bit(alist->preferred, &op->addr_tried))
-			WRITE_ONCE(alist->preferred, op->addr_index);
-		op->estate = NULL;
-	}
+	op->estate = NULL;
 	_leave(" = f [failed %d]", afs_op_error(op));
 	return false;
 }