From c6bc1422fa55033c1bd04c788203af8be2d5ce4c Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 2 Jun 2021 20:57:19 +0200 Subject: virtio-mem: simplify high-level unplug handling in Big Block Mode Let's simplify high-level big block selection when unplugging in Big Block Mode. Combine handling of offline and online blocks. We can get rid of virtio_mem_bbm_bb_is_offline() and simply use virtio_mem_bbm_offline_remove_and_unplug_bb(), as that already tolerates offline parts. We can race with concurrent onlining/offlining either way, so we don;t have to be super correct by failing if an offline big block we'd like to unplug just got (partially) onlined. Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20210602185720.31821-7-david@redhat.com Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_mem.c | 96 ++++++++++++--------------------------------- 1 file changed, 24 insertions(+), 72 deletions(-) (limited to 'drivers/virtio') diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 156a79ceb9fc..43199389c414 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -702,18 +702,6 @@ static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id) return virtio_mem_remove_memory(vm, addr, size); } -/* - * See virtio_mem_remove_memory(): Try to remove all Linux memory blocks covered - * by the big block. - */ -static int virtio_mem_bbm_remove_bb(struct virtio_mem *vm, unsigned long bb_id) -{ - const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id); - const uint64_t size = vm->bbm.bb_size; - - return virtio_mem_remove_memory(vm, addr, size); -} - /* * Try offlining and removing memory from Linux. * @@ -2114,35 +2102,6 @@ rollback_safe_unplug: return rc; } -/* - * Try to remove a big block from Linux and unplug it. Will fail with - * -EBUSY if some memory is online. - * - * Will modify the state of the memory block. - */ -static int virtio_mem_bbm_remove_and_unplug_bb(struct virtio_mem *vm, - unsigned long bb_id) -{ - int rc; - - if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) != - VIRTIO_MEM_BBM_BB_ADDED)) - return -EINVAL; - - rc = virtio_mem_bbm_remove_bb(vm, bb_id); - if (rc) - return -EBUSY; - - rc = virtio_mem_bbm_unplug_bb(vm, bb_id); - if (rc) - virtio_mem_bbm_set_bb_state(vm, bb_id, - VIRTIO_MEM_BBM_BB_PLUGGED); - else - virtio_mem_bbm_set_bb_state(vm, bb_id, - VIRTIO_MEM_BBM_BB_UNUSED); - return rc; -} - /* * Test if a big block is completely offline. */ @@ -2166,42 +2125,35 @@ static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff) { uint64_t nb_bb = diff / vm->bbm.bb_size; uint64_t bb_id; - int rc; + int rc, i; if (!nb_bb) return 0; - /* Try to unplug completely offline big blocks first. */ - virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) { - cond_resched(); - /* - * As we're holding no locks, this check is racy as memory - * can get onlined in the meantime - but we'll fail gracefully. - */ - if (!virtio_mem_bbm_bb_is_offline(vm, bb_id)) - continue; - rc = virtio_mem_bbm_remove_and_unplug_bb(vm, bb_id); - if (rc == -EBUSY) - continue; - if (!rc) - nb_bb--; - if (rc || !nb_bb) - return rc; - } - - if (!unplug_online) - return 0; + /* + * Try to unplug big blocks. Similar to SBM, start with offline + * big blocks. + */ + for (i = 0; i < 2; i++) { + virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) { + cond_resched(); - /* Try to unplug any big blocks. */ - virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) { - cond_resched(); - rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id); - if (rc == -EBUSY) - continue; - if (!rc) - nb_bb--; - if (rc || !nb_bb) - return rc; + /* + * As we're holding no locks, these checks are racy, + * but we don't care. + */ + if (i == 0 && !virtio_mem_bbm_bb_is_offline(vm, bb_id)) + continue; + rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id); + if (rc == -EBUSY) + continue; + if (!rc) + nb_bb--; + if (rc || !nb_bb) + return rc; + } + if (i == 0 && !unplug_online) + return 0; } return nb_bb ? -EBUSY : 0; -- cgit v1.2.3