[PATCH v3 2/2] hw/nvme: support online resize

[Alexander Mikhalitsyn <alexander@mihalicyn.com>]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Implement (BlockDevOps *)->resize_cb() for NVMe namespace to enable
online resize support.

We must handle cases when multiple namespaces are attached to
a single controller, or namespace is shared across a few
different controllers by iterating over controllers attached to
a NvmeSubsystem and properly notify every controller about a size change.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
v3:
    - rebased
v2:
    - check-patch fixes
---
 hw/nvme/ctrl.c |  9 +++++++
 hw/nvme/ns.c   | 68 +++++++++++++++++++++++++++++++++++++++++++++++++-
 hw/nvme/nvme.h |  2 ++
 3 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 710c3e0d77d..d60b3e105a1 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -7009,6 +7009,15 @@ static uint16_t nvme_ns_attachment(NvmeCtrl *n, NvmeRequest *req)
     return NVME_SUCCESS;
 }
 
+void nvme_ctrl_notify_ns_resize(NvmeCtrl *ctrl, NvmeNamespace *ns)
+{
+    if (!test_and_set_bit(ns->params.nsid, ctrl->changed_nsids)) {
+        nvme_enqueue_event(ctrl, NVME_AER_TYPE_NOTICE,
+                           NVME_AER_INFO_NOTICE_NS_ATTR_CHANGED,
+                           NVME_LOG_CHANGED_NSLIST);
+    }
+}
+
 typedef struct NvmeFormatAIOCB {
     BlockAIOCB common;
     BlockAIOCB *aiocb;
diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
index 7f0f9ac7662..e2954fd91b3 100644
--- a/hw/nvme/ns.c
+++ b/hw/nvme/ns.c
@@ -163,6 +163,70 @@ lbaf_found:
     return 0;
 }
 
+static void nvme_ns_resize_cb(void *opaque)
+{
+    NvmeNamespace *ns = opaque;
+    int64_t size;
+    int cntlid, notified_ctrls;
+
+    size = blk_getlength(ns->blkconf.blk);
+    if (size < 0) {
+        error_report("can't get size of block device %s: %s",
+                     blk_name(ns->blkconf.blk), strerror(-size));
+        return;
+    }
+
+    ns->size = size;
+    nvme_ns_init_format(ns);
+
+    if (!ns->attached) {
+        return;
+    }
+
+    /*
+     * Okay, the namespace is attached so we need to notify all controllers
+     * about size change.
+     *
+     * Let's just take ns->subsys, iterate over all controllers and find
+     * to which of them our namespace is attached.
+     */
+
+    assert(ns->subsys);
+    assert(ns->subsys->ctrls);
+
+    notified_ctrls = 0;
+    for (cntlid = 0; cntlid < ARRAY_SIZE(ns->subsys->ctrls); cntlid++) {
+        NvmeCtrl *ctrl;
+
+        /* notified everyone? */
+        if (notified_ctrls == ns->attached) {
+            break;
+        }
+
+        ctrl = nvme_subsys_ctrl(ns->subsys, cntlid);
+        if (!ctrl) {
+            continue;
+        }
+
+        for (uint32_t nsid = 1; nsid <= NVME_MAX_NAMESPACES; nsid++) {
+            NvmeNamespace *ns_iter = ctrl->namespaces[nsid];
+
+            if (!ns_iter || ns_iter != ns) {
+                continue;
+            }
+
+            nvme_ctrl_notify_ns_resize(ctrl, ns);
+
+            notified_ctrls++;
+            break;
+        }
+    }
+}
+
+static const BlockDevOps nvme_ns_block_ops = {
+    .resize_cb     = nvme_ns_resize_cb,
+};
+
 static int nvme_ns_init_blk(NvmeNamespace *ns, Error **errp)
 {
     bool read_only;
@@ -172,10 +236,12 @@ static int nvme_ns_init_blk(NvmeNamespace *ns, Error **errp)
     }
 
     read_only = !blk_supports_write_perm(ns->blkconf.blk);
-    if (!blkconf_apply_backend_options(&ns->blkconf, read_only, false, errp)) {
+    if (!blkconf_apply_backend_options(&ns->blkconf, read_only, true, errp)) {
         return -1;
     }
 
+    blk_set_dev_ops(ns->blkconf.blk, &nvme_ns_block_ops, ns);
+
     if (ns->blkconf.discard_granularity == -1) {
         ns->blkconf.discard_granularity =
             MAX(ns->blkconf.logical_block_size, MIN_DISCARD_GRANULARITY);
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index 43e3c916f73..a4b2c01a2cc 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -764,6 +764,8 @@ void nvme_atomic_configure_max_write_size(bool dn, uint16_t awun,
 void nvme_ns_atomic_configure_boundary(bool dn, uint16_t nabsn,
                                        uint16_t nabspf, NvmeAtomic *atomic);
 
+void nvme_ctrl_notify_ns_resize(NvmeCtrl *ctrl, NvmeNamespace *ns);
+
 extern const VMStateDescription nvme_vmstate_atomic;
 extern const VMStateDescription nvme_vmstate_ns;
 
-- 
2.47.3