nvme: avoid an Identify Controller command for each namespace scan

The namespace lists are 0-terminated, so we don't really need the NN value
execept for the legacy sequential scan.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 42102b8..15b6342 100644 (file)
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3740,12 +3740,11 @@ static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl,
 
 }
 
-static int nvme_scan_ns_list(struct nvme_ctrl *ctrl, unsigned nn)
+static int nvme_scan_ns_list(struct nvme_ctrl *ctrl)
 {
        __le32 *ns_list;
-       unsigned i, j, nsid, prev = 0;
-       unsigned num_lists = DIV_ROUND_UP_ULL((u64)nn, 1024);
-       int ret = 0;
+       u32 prev = 0;
+       int ret = 0, i;
 
        if (nvme_ctrl_limited_cns(ctrl))
                return -EOPNOTSUPP;
@@ -3754,22 +3753,20 @@ static int nvme_scan_ns_list(struct nvme_ctrl *ctrl, unsigned nn)
        if (!ns_list)
                return -ENOMEM;
 
-       for (i = 0; i < num_lists; i++) {
+       for (;;) {
                ret = nvme_identify_ns_list(ctrl, prev, ns_list);
                if (ret)
                        goto free;
 
-               for (j = 0; j < min(nn, 1024U); j++) {
-                       nsid = le32_to_cpu(ns_list[j]);
-                       if (!nsid)
-                               goto out;
+               for (i = 0; i < 1024; i++) {
+                       u32 nsid = le32_to_cpu(ns_list[i]);
 
+                       if (!nsid)      /* end of the list? */
+                               goto out;
                        nvme_validate_ns(ctrl, nsid);
-
                        while (++prev < nsid)
                                nvme_ns_remove_by_nsid(ctrl, prev);
                }
-               nn -= j;
        }
  out:
        nvme_remove_invalid_namespaces(ctrl, prev);
@@ -3778,9 +3775,15 @@ static int nvme_scan_ns_list(struct nvme_ctrl *ctrl, unsigned nn)
        return ret;
 }
 
-static void nvme_scan_ns_sequential(struct nvme_ctrl *ctrl, unsigned nn)
+static void nvme_scan_ns_sequential(struct nvme_ctrl *ctrl)
 {
-       unsigned i;
+       struct nvme_id_ctrl *id;
+       u32 nn, i;
+
+       if (nvme_identify_ctrl(ctrl, &id))
+               return;
+       nn = le32_to_cpu(id->nn);
+       kfree(id);
 
        for (i = 1; i <= nn; i++)
                nvme_validate_ns(ctrl, i);
@@ -3817,8 +3820,6 @@ static void nvme_scan_work(struct work_struct *work)
 {
        struct nvme_ctrl *ctrl =
                container_of(work, struct nvme_ctrl, scan_work);
-       struct nvme_id_ctrl *id;
-       unsigned nn;
 
        /* No tagset on a live ctrl means IO queues could not created */
        if (ctrl->state != NVME_CTRL_LIVE || !ctrl->tagset)
@@ -3829,14 +3830,9 @@ static void nvme_scan_work(struct work_struct *work)
                nvme_clear_changed_ns_log(ctrl);
        }
 
-       if (nvme_identify_ctrl(ctrl, &id))
-               return;
-       nn = le32_to_cpu(id->nn);
-       kfree(id);
-
        mutex_lock(&ctrl->scan_lock);
-       if (nvme_scan_ns_list(ctrl, nn) != 0)
-               nvme_scan_ns_sequential(ctrl, nn);
+       if (nvme_scan_ns_list(ctrl) != 0)
+               nvme_scan_ns_sequential(ctrl);
        mutex_unlock(&ctrl->scan_lock);
 
        down_write(&ctrl->namespaces_rwsem);