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 <david@xxxxxxxxxx>
---
drivers/virtio/virtio_mem.c | 96 ++++++++++---------------------------
1 file changed, 24 insertions(+), 72 deletions(-)
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 @@ static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
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;
--
2.31.1
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