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Message-ID: <ef4a53e0-760e-4ec8-9fdf-f4e8f36360c0@suse.de>
Date: Mon, 21 Jul 2025 08:01:11 +0200
From: Hannes Reinecke <hare@...e.de>
To: Yu Kuai <yukuai1@...weicloud.com>, corbet@....net, agk@...hat.com,
snitzer@...nel.org, mpatocka@...hat.com, song@...nel.org, yukuai3@...wei.com
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
dm-devel@...ts.linux.dev, linux-raid@...r.kernel.org, yi.zhang@...wei.com,
yangerkun@...wei.com, johnny.chenyi@...wei.com
Subject: Re: [PATCH v3 06/11] md/md-bitmap: delay registration of bitmap_ops
until creating bitmap
On 7/18/25 11:23, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@...wei.com>
>
> 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.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> Documentation/admin-guide/md.rst | 3 ++
> drivers/md/md.c | 82 +++++++++++++++++++++-----------
> 2 files changed, 56 insertions(+), 29 deletions(-)
>
> diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
> index 356d2a344f08..03a9f5025f99 100644
> --- 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 will be
> +created after md device KOBJ_CHANGE event.
> +
> If bitmap_type is bitmap, then the md device will also contain:
>
> bitmap/location
Please state _which_ attributes are created with the KOBJ_CHANGE
event.
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index d8b0dfdb4bfc..639b0143cbb1 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -674,9 +674,11 @@ 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);
> @@ -694,6 +696,18 @@ static bool mddev_set_bitmap_ops(struct mddev *mddev)
>
> mddev->bitmap_ops = (void *)head;
> xa_unlock(&md_submodule);
> +
> + if (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:
> @@ -703,28 +717,25 @@ static bool mddev_set_bitmap_ops(struct mddev *mddev)
>
> static void mddev_clear_bitmap_ops(struct mddev *mddev)
> {
> + if (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;
> }
> @@ -752,6 +763,7 @@ int mddev_init(struct mddev *mddev)
> mddev->resync_min = 0;
> mddev->resync_max = MaxSector;
> mddev->level = LEVEL_NONE;
> + mddev->bitmap_id = ID_BITMAP;
>
> INIT_WORK(&mddev->sync_work, md_start_sync);
> INIT_WORK(&mddev->del_work, mddev_delayed_delete);
> @@ -762,7 +774,6 @@ 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);
> }
> @@ -6125,11 +6136,6 @@ 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");
> @@ -6205,6 +6211,26 @@ 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;
> @@ -6369,9 +6395,9 @@ 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);
> @@ -6444,8 +6470,7 @@ int md_run(struct mddev *mddev)
> 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:
> @@ -6468,7 +6493,7 @@ 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;
> }
> }
> @@ -6659,8 +6684,7 @@ 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;
> @@ -7440,16 +7464,16 @@ 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);
> }
> }
>
> @@ -7764,12 +7788,12 @@ 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;
>
> @@ -7795,7 +7819,7 @@ 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;
> }
> }
Otherwise:
Reviewed-by: Hannes Reinecke <hare@...e.de>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@...e.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
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