From da0e01cc7079124cb1e86a2c35dd90ba12897e1a Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 3 May 2024 15:22:32 +0100 Subject: [PATCH] afs: Fix fileserver rotation getting stuck Fix the fileserver rotation code in a couple of ways: (1) op->server_states is an array, not a pointer to a single record, so fix the places that access it to index it. (2) In the places that go through an address list to work out which one has the best priority, fix the loops to skip known failed addresses. Without this, the rotation algorithm may get stuck on addresses that are inaccessible or don't respond. This can be triggered manually by finding a server that advertises a non-routable address and giving it a higher priority, eg.: echo "add udp 192.168.0.0/16 3000" >/proc/fs/afs/addr_prefs if the server, say, includes the address 192.168.7.7 in its address list, and then attempting to access a volume on that server. Fixes: 495f2ae9e355 ("afs: Fix fileserver rotation") Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/4005300.1712309731@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/998836.1714746152@warthog.procyon.org.uk Signed-off-by: Christian Brauner --- fs/afs/rotate.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c index ed04bd1eeae89..ed09d4d4c2112 100644 --- a/fs/afs/rotate.c +++ b/fs/afs/rotate.c @@ -541,11 +541,13 @@ bool afs_select_fileserver(struct afs_operation *op) test_bit(AFS_SE_EXCLUDED, &se->flags) || !test_bit(AFS_SERVER_FL_RESPONDING, &s->flags)) continue; - es = op->server_states->endpoint_state; + es = op->server_states[i].endpoint_state; sal = es->addresses; afs_get_address_preferences_rcu(op->net, sal); for (j = 0; j < sal->nr_addrs; j++) { + if (es->failed_set & (1 << j)) + continue; if (!sal->addrs[j].peer) continue; if (sal->addrs[j].prio > best_prio) { @@ -605,6 +607,8 @@ bool afs_select_fileserver(struct afs_operation *op) best_prio = -1; addr_index = 0; for (i = 0; i < alist->nr_addrs; i++) { + if (!(set & (1 << i))) + continue; if (alist->addrs[i].prio > best_prio) { addr_index = i; best_prio = alist->addrs[i].prio; @@ -674,7 +678,7 @@ bool afs_select_fileserver(struct afs_operation *op) for (i = 0; i < op->server_list->nr_servers; i++) { struct afs_endpoint_state *estate; - estate = op->server_states->endpoint_state; + estate = op->server_states[i].endpoint_state; error = READ_ONCE(estate->error); if (error < 0) afs_op_accumulate_error(op, error, estate->abort_code);