md/md-bitmap: delay registration of bitmap_ops until creating bitmap

Currently bitmap_ops is registered while allocating mddev, this is fine
when there is only one bitmap_ops.

Delay setting bitmap_ops until creating bitmap, so that user can choose
which bitmap to use before running the array.

Link: https://lore.kernel.org/linux-raid/20250721171557.34587-7-yukuai@kernel.org
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Li Nan <linan122@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
index 356d2a344f087731d7f7f920bfa6f070363130ff..001363f818507fe303d19b53d9db13e8aee14178 100644 (file)
--- a/Documentation/admin-guide/md.rst
+++ b/Documentation/admin-guide/md.rst
@@ -388,6 +388,9 @@ All md devices contain:
      bitmap
          The default internal bitmap
 
+If bitmap_type is not none, then additional bitmap attributes bitmap/xxx or
+llbitmap/xxx will be created after md device KOBJ_CHANGE event.
+
 If bitmap_type is bitmap, then the md device will also contain:
 
   bitmap/location

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 17cb33054ecfc2ff53b355933ea8f2bd36e37f8a..51dee0a98af1c926be4479b99df1a5eec6e20c8d 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -678,9 +678,11 @@ static void no_op(struct percpu_ref *r) {}
 
 static bool mddev_set_bitmap_ops(struct mddev *mddev)
 {
+       struct bitmap_operations *old = mddev->bitmap_ops;
        struct md_submodule_head *head;
 
-       if (mddev->bitmap_id == ID_BITMAP_NONE)
+       if (mddev->bitmap_id == ID_BITMAP_NONE ||
+           (old && old->head.id == mddev->bitmap_id))
                return true;
 
        xa_lock(&md_submodule);
@@ -698,6 +700,18 @@ static bool mddev_set_bitmap_ops(struct mddev *mddev)
 
        mddev->bitmap_ops = (void *)head;
        xa_unlock(&md_submodule);
+
+       if (!mddev_is_dm(mddev) && mddev->bitmap_ops->group) {
+               if (sysfs_create_group(&mddev->kobj, mddev->bitmap_ops->group))
+                       pr_warn("md: cannot register extra bitmap attributes for %s\n",
+                               mdname(mddev));
+               else
+                       /*
+                        * Inform user with KOBJ_CHANGE about new bitmap
+                        * attributes.
+                        */
+                       kobject_uevent(&mddev->kobj, KOBJ_CHANGE);
+       }
        return true;
 
 err:
@@ -707,28 +721,26 @@ err:
 
 static void mddev_clear_bitmap_ops(struct mddev *mddev)
 {
+       if (!mddev_is_dm(mddev) && mddev->bitmap_ops &&
+           mddev->bitmap_ops->group)
+               sysfs_remove_group(&mddev->kobj, mddev->bitmap_ops->group);
+
        mddev->bitmap_ops = NULL;
 }
 
 int mddev_init(struct mddev *mddev)
 {
-       if (!IS_ENABLED(CONFIG_MD_BITMAP)) {
+       if (!IS_ENABLED(CONFIG_MD_BITMAP))
                mddev->bitmap_id = ID_BITMAP_NONE;
-       } else {
+       else
                mddev->bitmap_id = ID_BITMAP;
-               if (!mddev_set_bitmap_ops(mddev))
-                       return -EINVAL;
-       }
 
        if (percpu_ref_init(&mddev->active_io, active_io_release,
-                           PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
-               mddev_clear_bitmap_ops(mddev);
+                           PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))
                return -ENOMEM;
-       }
 
        if (percpu_ref_init(&mddev->writes_pending, no_op,
                            PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
-               mddev_clear_bitmap_ops(mddev);
                percpu_ref_exit(&mddev->active_io);
                return -ENOMEM;
        }
@@ -766,7 +778,6 @@ EXPORT_SYMBOL_GPL(mddev_init);
 
 void mddev_destroy(struct mddev *mddev)
 {
-       mddev_clear_bitmap_ops(mddev);
        percpu_ref_exit(&mddev->active_io);
        percpu_ref_exit(&mddev->writes_pending);
 }
@@ -6196,11 +6207,6 @@ struct mddev *md_alloc(dev_t dev, char *name)
                return ERR_PTR(error);
        }
 
-       if (md_bitmap_registered(mddev) && mddev->bitmap_ops->group)
-               if (sysfs_create_group(&mddev->kobj, mddev->bitmap_ops->group))
-                       pr_warn("md: cannot register extra bitmap attributes for %s\n",
-                               mdname(mddev));
-
        kobject_uevent(&mddev->kobj, KOBJ_ADD);
        mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
        mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
@@ -6279,6 +6285,26 @@ static void md_safemode_timeout(struct timer_list *t)
 
 static int start_dirty_degraded;
 
+static int md_bitmap_create(struct mddev *mddev)
+{
+       if (mddev->bitmap_id == ID_BITMAP_NONE)
+               return -EINVAL;
+
+       if (!mddev_set_bitmap_ops(mddev))
+               return -ENOENT;
+
+       return mddev->bitmap_ops->create(mddev);
+}
+
+static void md_bitmap_destroy(struct mddev *mddev)
+{
+       if (!md_bitmap_registered(mddev))
+               return;
+
+       mddev->bitmap_ops->destroy(mddev);
+       mddev_clear_bitmap_ops(mddev);
+}
+
 int md_run(struct mddev *mddev)
 {
        int err;
@@ -6443,9 +6469,9 @@ int md_run(struct mddev *mddev)
                        (unsigned long long)pers->size(mddev, 0, 0) / 2);
                err = -EINVAL;
        }
-       if (err == 0 && pers->sync_request && md_bitmap_registered(mddev) &&
+       if (err == 0 && pers->sync_request &&
            (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
-               err = mddev->bitmap_ops->create(mddev);
+               err = md_bitmap_create(mddev);
                if (err)
                        pr_warn("%s: failed to create bitmap (%d)\n",
                                mdname(mddev), err);
@@ -6518,8 +6544,7 @@ bitmap_abort:
                pers->free(mddev, mddev->private);
        mddev->private = NULL;
        put_pers(pers);
-       if (md_bitmap_registered(mddev))
-               mddev->bitmap_ops->destroy(mddev);
+       md_bitmap_destroy(mddev);
 abort:
        bioset_exit(&mddev->io_clone_set);
 exit_sync_set:
@@ -6542,7 +6567,7 @@ int do_md_run(struct mddev *mddev)
        if (md_bitmap_registered(mddev)) {
                err = mddev->bitmap_ops->load(mddev);
                if (err) {
-                       mddev->bitmap_ops->destroy(mddev);
+                       md_bitmap_destroy(mddev);
                        goto out;
                }
        }
@@ -6740,8 +6765,7 @@ static void __md_stop(struct mddev *mddev)
 {
        struct md_personality *pers = mddev->pers;
 
-       if (md_bitmap_registered(mddev))
-               mddev->bitmap_ops->destroy(mddev);
+       md_bitmap_destroy(mddev);
        mddev_detach(mddev);
        spin_lock(&mddev->lock);
        mddev->pers = NULL;
@@ -7518,16 +7542,16 @@ static int set_bitmap_file(struct mddev *mddev, int fd)
        err = 0;
        if (mddev->pers) {
                if (fd >= 0) {
-                       err = mddev->bitmap_ops->create(mddev);
+                       err = md_bitmap_create(mddev);
                        if (!err)
                                err = mddev->bitmap_ops->load(mddev);
 
                        if (err) {
-                               mddev->bitmap_ops->destroy(mddev);
+                               md_bitmap_destroy(mddev);
                                fd = -1;
                        }
                } else if (fd < 0) {
-                       mddev->bitmap_ops->destroy(mddev);
+                       md_bitmap_destroy(mddev);
                }
        }
 
@@ -7812,14 +7836,6 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
                rv = update_raid_disks(mddev, info->raid_disks);
 
        if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
-               /*
-                * Metadata says bitmap existed, however kernel can't find
-                * registered bitmap.
-                */
-               if (WARN_ON_ONCE(!md_bitmap_registered(mddev))) {
-                       rv = -EINVAL;
-                       goto err;
-               }
                if (mddev->pers->quiesce == NULL || mddev->thread == NULL) {
                        rv = -EINVAL;
                        goto err;
@@ -7842,12 +7858,12 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
                                mddev->bitmap_info.default_offset;
                        mddev->bitmap_info.space =
                                mddev->bitmap_info.default_space;
-                       rv = mddev->bitmap_ops->create(mddev);
+                       rv = md_bitmap_create(mddev);
                        if (!rv)
                                rv = mddev->bitmap_ops->load(mddev);
 
                        if (rv)
-                               mddev->bitmap_ops->destroy(mddev);
+                               md_bitmap_destroy(mddev);
                } else {
                        struct md_bitmap_stats stats;
 
@@ -7873,7 +7889,7 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
                                put_cluster_ops(mddev);
                                mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
                        }
-                       mddev->bitmap_ops->destroy(mddev);
+                       md_bitmap_destroy(mddev);
                        mddev->bitmap_info.offset = 0;
                }
        }