From d626338735909bc2b2e7cafc332f44ed41cfdeee Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 4 Aug 2021 11:41:43 +0200 Subject: block: support delayed holder registration device mapper needs to register holders before it is ready to do I/O. Currently it does so by registering the disk early, which can leave the disk and queue in a weird half state where the queue is registered with the disk, except for sysfs and the elevator. And this state has been a bit promlematic before, and will get more so when sorting out the responsibilities between the queue and the disk. Support registering holders on an initialized but not registered disk instead by delaying the sysfs registration until the disk is registered. Signed-off-by: Christoph Hellwig Reviewed-by: Mike Snitzer Link: https://lore.kernel.org/r/20210804094147.459763-5-hch@lst.de Signed-off-by: Jens Axboe --- block/holder.c | 68 +++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 51 insertions(+), 17 deletions(-) (limited to 'block/holder.c') diff --git a/block/holder.c b/block/holder.c index 11e65d99a9fb..4568cc4f6827 100644 --- a/block/holder.c +++ b/block/holder.c @@ -28,6 +28,19 @@ static void del_symlink(struct kobject *from, struct kobject *to) sysfs_remove_link(from, kobject_name(to)); } +static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk) +{ + int ret; + + ret = add_symlink(disk->slave_dir, bdev_kobj(bdev)); + if (ret) + return ret; + ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); + if (ret) + del_symlink(disk->slave_dir, bdev_kobj(bdev)); + return ret; +} + /** * bd_link_disk_holder - create symlinks between holding disk and slave bdev * @bdev: the claimed slave bdev @@ -66,7 +79,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) WARN_ON_ONCE(!bdev->bd_holder); /* FIXME: remove the following once add_disk() handles errors */ - if (WARN_ON(!disk->slave_dir || !bdev->bd_holder_dir)) + if (WARN_ON(!bdev->bd_holder_dir)) goto out_unlock; holder = bd_find_holder_disk(bdev, disk); @@ -84,28 +97,28 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) INIT_LIST_HEAD(&holder->list); holder->bdev = bdev; holder->refcnt = 1; - - ret = add_symlink(disk->slave_dir, bdev_kobj(bdev)); - if (ret) - goto out_free; - - ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); - if (ret) - goto out_del; + if (disk->slave_dir) { + ret = __link_disk_holder(bdev, disk); + if (ret) { + kfree(holder); + goto out_unlock; + } + } list_add(&holder->list, &disk->slave_bdevs); - goto out_unlock; - -out_del: - del_symlink(disk->slave_dir, bdev_kobj(bdev)); -out_free: - kfree(holder); out_unlock: mutex_unlock(&disk->open_mutex); return ret; } EXPORT_SYMBOL_GPL(bd_link_disk_holder); +static void __unlink_disk_holder(struct block_device *bdev, + struct gendisk *disk) +{ + del_symlink(disk->slave_dir, bdev_kobj(bdev)); + del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); +} + /** * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() * @bdev: the calimed slave bdev @@ -123,11 +136,32 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) mutex_lock(&disk->open_mutex); holder = bd_find_holder_disk(bdev, disk); if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { - del_symlink(disk->slave_dir, bdev_kobj(bdev)); - del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); + if (disk->slave_dir) + __unlink_disk_holder(bdev, disk); list_del_init(&holder->list); kfree(holder); } mutex_unlock(&disk->open_mutex); } EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); + +int bd_register_pending_holders(struct gendisk *disk) +{ + struct bd_holder_disk *holder; + int ret; + + mutex_lock(&disk->open_mutex); + list_for_each_entry(holder, &disk->slave_bdevs, list) { + ret = __link_disk_holder(holder->bdev, disk); + if (ret) + goto out_undo; + } + mutex_unlock(&disk->open_mutex); + return 0; + +out_undo: + list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list) + __unlink_disk_holder(holder->bdev, disk); + mutex_unlock(&disk->open_mutex); + return ret; +} -- cgit v1.2.3-58-ga151