Patch "afs: Don't cache preferred address" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    afs: Don't cache preferred address

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     afs-don-t-cache-preferred-address.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0f861a92f74159529fd326aa63e958f4006cd058
Author: David Howells <dhowells@xxxxxxxxxx>
Date:   Wed Mar 13 08:15:02 2024 +0000

    afs: Don't cache preferred address
    
    [ Upstream commit 83505bde45e347f1451d007b3ddd7f06cee4c269 ]
    
    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.
    
    Fixes: 495f2ae9e355 ("afs: Fix fileserver rotation")
    Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240313081505.3060173-2-dhowells@xxxxxxxxxx
    Reviewed-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
    cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
    cc: linux-afs@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 700a27bc8c257..ed04bd1eeae89 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;
 }