From c0fe2994f9a9d0a2ec9e42441ea5ba74b6a16176 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Mon, 5 Jan 2026 19:23:19 +0100 Subject: [PATCH] libceph: make calc_target() set t->paused, not just clear it Currently calc_target() clears t->paused if the request shouldn't be paused anymore, but doesn't ever set t->paused even though it's able to determine when the request should be paused. Setting t->paused is left to __submit_request() which is fine for regular requests but doesn't work for linger requests -- since __submit_request() doesn't operate on linger requests, there is nowhere for lreq->t.paused to be set. One consequence of this is that watches don't get reestablished on paused -> unpaused transitions in cases where requests have been paused long enough for the (paused) unwatch request to time out and for the subsequent (re)watch request to enter the paused state. On top of the watch not getting reestablished, rbd_reregister_watch() gets stuck with rbd_dev->watch_mutex held: rbd_register_watch __rbd_register_watch ceph_osdc_watch linger_reg_commit_wait It's waiting for lreq->reg_commit_wait to be completed, but for that to happen the respective request needs to end up on need_resend_linger list and be kicked when requests are unpaused. There is no chance for that if the request in question is never marked paused in the first place. The fact that rbd_dev->watch_mutex remains taken out forever then prevents the image from getting unmapped -- "rbd unmap" would inevitably hang in D state on an attempt to grab the mutex. Cc: stable@vger.kernel.org Reported-by: Raphael Zimmer Signed-off-by: Ilya Dryomov Reviewed-by: Viacheslav Dubeyko --- net/ceph/osd_client.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index 1a7be2f615dc..610e584524d1 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -1586,6 +1586,7 @@ static enum calc_target_result calc_target(struct ceph_osd_client *osdc, struct ceph_pg_pool_info *pi; struct ceph_pg pgid, last_pgid; struct ceph_osds up, acting; + bool should_be_paused; bool is_read = t->flags & CEPH_OSD_FLAG_READ; bool is_write = t->flags & CEPH_OSD_FLAG_WRITE; bool force_resend = false; @@ -1654,10 +1655,16 @@ static enum calc_target_result calc_target(struct ceph_osd_client *osdc, &last_pgid)) force_resend = true; - if (t->paused && !target_should_be_paused(osdc, t, pi)) { - t->paused = false; + should_be_paused = target_should_be_paused(osdc, t, pi); + if (t->paused && !should_be_paused) { unpaused = true; } + if (t->paused != should_be_paused) { + dout("%s t %p paused %d -> %d\n", __func__, t, t->paused, + should_be_paused); + t->paused = should_be_paused; + } + legacy_change = ceph_pg_compare(&t->pgid, &pgid) || ceph_osds_changed(&t->acting, &acting, t->used_replica || any_change);