linux-kernel - Re: [PATCH md-6.15 1/7] md: merge common code into find

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Message-Id: <CF631B40-3430-4ADC-BB6D-D535B3AF5D9E@suse.com>
Date: Mon, 17 Feb 2025 18:16:42 +0800
From: Glass Su <glass.su@...e.com>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: song@...nel.org,
 yukuai3@...wei.com,
 linux-raid@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 yi.zhang@...wei.com,
 yangerkun@...wei.com
Subject: Re: [PATCH md-6.15 1/7] md: merge common code into find_pers()



> On Feb 15, 2025, at 17:22, Yu Kuai <yukuai1@...weicloud.com> wrote:
> 
> From: Yu Kuai <yukuai3@...wei.com>
> 
> - pers_lock() are held and released from caller
> - try_module_get() is called from caller
> - error message from caller
> 
> Merge above code into find_pers(), and rename it to get_pers(), also
> add a wrapper to module_put() as put_pers().
> 
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>

Reviewed-by: Su Yue <glass.su@...e.com>
> ---
> drivers/md/md.c | 68 +++++++++++++++++++++++++++----------------------
> 1 file changed, 38 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 30b3dbbce2d2..37f3a89eba94 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -888,16 +888,37 @@ struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev)
> }
> EXPORT_SYMBOL_GPL(md_find_rdev_rcu);
> 
> -static struct md_personality *find_pers(int level, char *clevel)
> +static struct md_personality *get_pers(int level, char *clevel)
> {
> + struct md_personality *ret = NULL;
> struct md_personality *pers;
> +
> + spin_lock(&pers_lock);
> list_for_each_entry(pers, &pers_list, list) {
> - if (level != LEVEL_NONE && pers->level == level)
> - return pers;
> - if (strcmp(pers->name, clevel)==0)
> - return pers;
> + if ((level != LEVEL_NONE && pers->level == level) ||
> +    !strcmp(pers->name, clevel)) {
> + if (try_module_get(pers->owner))
> + ret = pers;
> + break;
> + }
> }
> - return NULL;
> + spin_unlock(&pers_lock);
> +
> + if (!ret) {
> + if (level != LEVEL_NONE)
> + pr_warn("md: personality for level %d is not loaded!\n",
> + level);
> + else
> + pr_warn("md: personality for level %s is not loaded!\n",
> + clevel);
> + }
> +
> + return ret;
> +}
> +
> +static void put_pers(struct md_personality *pers)
> +{
> + module_put(pers->owner);
> }
> 
> /* return the offset of the super block in 512byte sectors */
> @@ -3931,24 +3952,20 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
> 
> if (request_module("md-%s", clevel) != 0)
> request_module("md-level-%s", clevel);
> - spin_lock(&pers_lock);
> - pers = find_pers(level, clevel);
> - if (!pers || !try_module_get(pers->owner)) {
> - spin_unlock(&pers_lock);
> - pr_warn("md: personality %s not loaded\n", clevel);
> + pers = get_pers(level, clevel);
> + if (!pers) {
> rv = -EINVAL;
> goto out_unlock;
> }
> - spin_unlock(&pers_lock);
> 
> if (pers == mddev->pers) {
> /* Nothing to do! */
> - module_put(pers->owner);
> + put_pers(pers);
> rv = len;
> goto out_unlock;
> }
> if (!pers->takeover) {
> - module_put(pers->owner);
> + put_pers(pers);
> pr_warn("md: %s: %s does not support personality takeover\n",
> mdname(mddev), clevel);
> rv = -EINVAL;
> @@ -3969,7 +3986,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
> mddev->raid_disks -= mddev->delta_disks;
> mddev->delta_disks = 0;
> mddev->reshape_backwards = 0;
> - module_put(pers->owner);
> + put_pers(pers);
> pr_warn("md: %s: %s would not accept array\n",
> mdname(mddev), clevel);
> rv = PTR_ERR(priv);
> @@ -4026,7 +4043,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
> mddev->to_remove = &md_redundancy_group;
> }
> 
> - module_put(oldpers->owner);
> + put_pers(oldpers);
> 
> rdev_for_each(rdev, mddev) {
> if (rdev->raid_disk < 0)
> @@ -6096,20 +6113,11 @@ int md_run(struct mddev *mddev)
> goto exit_sync_set;
> }
> 
> - spin_lock(&pers_lock);
> - pers = find_pers(mddev->level, mddev->clevel);
> - if (!pers || !try_module_get(pers->owner)) {
> - spin_unlock(&pers_lock);
> - if (mddev->level != LEVEL_NONE)
> - pr_warn("md: personality for level %d is not loaded!\n",
> - mddev->level);
> - else
> - pr_warn("md: personality for level %s is not loaded!\n",
> - mddev->clevel);
> + pers = get_pers(mddev->level, mddev->clevel);
> + if (!pers) {
> err = -EINVAL;
> goto abort;
> }
> - spin_unlock(&pers_lock);
> if (mddev->level != pers->level) {
> mddev->level = pers->level;
> mddev->new_level = pers->level;
> @@ -6119,7 +6127,7 @@ int md_run(struct mddev *mddev)
> if (mddev->reshape_position != MaxSector &&
>    pers->start_reshape == NULL) {
> /* This personality cannot handle reshaping... */
> - module_put(pers->owner);
> + put_pers(pers);
> err = -EINVAL;
> goto abort;
> }
> @@ -6246,7 +6254,7 @@ int md_run(struct mddev *mddev)
> if (mddev->private)
> pers->free(mddev, mddev->private);
> mddev->private = NULL;
> - module_put(pers->owner);
> + put_pers(pers);
> mddev->bitmap_ops->destroy(mddev);
> abort:
> bioset_exit(&mddev->io_clone_set);
> @@ -6467,7 +6475,7 @@ static void __md_stop(struct mddev *mddev)
> mddev->private = NULL;
> if (pers->sync_request && mddev->to_remove == NULL)
> mddev->to_remove = &md_redundancy_group;
> - module_put(pers->owner);
> + put_pers(pers);
> clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
> 
> bioset_exit(&mddev->bio_set);
> -- 
> 2.39.2
> 
>