DM is now no longer prone to having its request_queue be improperly initialized.
Summary of changes: - defer DM's blk_register_queue() from add_disk()-time until dm_setup_md_queue() by setting QUEUE_FLAG_DEFER_REG in alloc_dev(). - dm_setup_md_queue() is updated to fully initialize DM's request_queue (_after_ all table loads have occurred and the request_queue's type, features and limits are known). - various other small improvements that were noticed along the way. A very welcome side-effect of these changes is DM no longer needs to: 1) backfill the "mq" sysfs entry (because historically DM didn't initialize the request_queue to use blk-mq until _after_ register_queue() was called via add_disk()). 2) call elv_register_queue() to get .request_fn request-based DM device's "queue" exposed in syfs. In addition, blk-mq debugfs support is now made available because request-based DM's blk-mq request_queue is now properly initialized before blk_register_queue() is called. These changes also stave off the need to introduce new DM-specific workarounds in block core, e.g. this proposal: https://patchwork.kernel.org/patch/10067961/ In the end DM devices should be less unicorn in nature (relative to initialization and availability of block core infrastructure). Signed-off-by: Mike Snitzer <snit...@redhat.com> --- drivers/md/dm-core.h | 2 -- drivers/md/dm-rq.c | 11 ----------- drivers/md/dm.c | 44 ++++++++++++++++++++++++++------------------ 3 files changed, 26 insertions(+), 31 deletions(-) diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h index 6a14f945783c..f955123b4765 100644 --- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -130,8 +130,6 @@ struct mapped_device { struct srcu_struct io_barrier; }; -void dm_init_md_queue(struct mapped_device *md); -void dm_init_normal_md_queue(struct mapped_device *md); int md_in_flight(struct mapped_device *md); void disable_write_same(struct mapped_device *md); void disable_write_zeroes(struct mapped_device *md); diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 9d32f25489c2..3b319776d80c 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -700,7 +700,6 @@ int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t) /* disable dm_old_request_fn's merge heuristic by default */ md->seq_rq_merge_deadline_usecs = 0; - dm_init_normal_md_queue(md); blk_queue_softirq_done(md->queue, dm_softirq_done); /* Initialize the request-based DM worker thread */ @@ -713,8 +712,6 @@ int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t) return error; } - elv_register_queue(md->queue); - return 0; } @@ -810,17 +807,9 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) err = PTR_ERR(q); goto out_tag_set; } - dm_init_md_queue(md); - - /* backfill 'mq' sysfs registration normally done in blk_register_queue */ - err = blk_mq_register_dev(disk_to_dev(md->disk), q); - if (err) - goto out_cleanup_queue; return 0; -out_cleanup_queue: - blk_cleanup_queue(q); out_tag_set: blk_mq_free_tag_set(md->tag_set); out_kfree_tag_set: diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 7475739fee49..f5d61b6adaec 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1626,20 +1626,9 @@ static const struct dax_operations dm_dax_ops; static void dm_wq_work(struct work_struct *work); -void dm_init_md_queue(struct mapped_device *md) -{ - /* - * Initialize data that will only be used by a non-blk-mq DM queue - * - must do so here (in alloc_dev callchain) before queue is used - */ - md->queue->queuedata = md; - md->queue->backing_dev_info->congested_data = md; -} - -void dm_init_normal_md_queue(struct mapped_device *md) +static void dm_init_normal_md_queue(struct mapped_device *md) { md->use_blk_mq = false; - dm_init_md_queue(md); /* * Initialize aspects of queue that aren't relevant for blk-mq @@ -1734,10 +1723,15 @@ static struct mapped_device *alloc_dev(int minor) md->queue = blk_alloc_queue_node(GFP_KERNEL, numa_node_id); if (!md->queue) goto bad; + md->queue->queuedata = md; + md->queue->backing_dev_info->congested_data = md; + /* + * Do not allow add_disk() to blk_register_queue(). + * Defer blk_register_queue() until dm_setup_md_queue(). + */ + queue_flag_set_unlocked(QUEUE_FLAG_DEFER_REG, md->queue); - dm_init_md_queue(md); - - md->disk = alloc_disk_node(1, numa_node_id); + md->disk = alloc_disk_node(1, md->numa_node_id); if (!md->disk) goto bad; @@ -1962,13 +1956,18 @@ static struct dm_table *__unbind(struct mapped_device *md) */ int dm_create(int minor, struct mapped_device **result) { + int r; struct mapped_device *md; md = alloc_dev(minor); if (!md) return -ENXIO; - dm_sysfs_init(md); + r = dm_sysfs_init(md); + if (r) { + free_dev(md); + return r; + } *result = md; return 0; @@ -2021,10 +2020,12 @@ EXPORT_SYMBOL_GPL(dm_get_queue_limits); int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) { int r; + struct queue_limits limits; enum dm_queue_mode type = dm_get_md_type(md); switch (type) { case DM_TYPE_REQUEST_BASED: + dm_init_normal_md_queue(md); r = dm_old_init_request_queue(md, t); if (r) { DMERR("Cannot initialize queue for request-based mapped device"); @@ -2057,6 +2058,14 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) break; } + r = dm_calculate_queue_limits(t, &limits); + if (r) { + DMERR("Cannot calculate initial queue limits"); + return r; + } + dm_table_set_restrictions(t, md->queue, &limits); + blk_register_queue(md->disk); + return 0; } @@ -2121,7 +2130,6 @@ EXPORT_SYMBOL_GPL(dm_device_name); static void __dm_destroy(struct mapped_device *md, bool wait) { - struct request_queue *q = dm_get_md_queue(md); struct dm_table *map; int srcu_idx; @@ -2132,7 +2140,7 @@ static void __dm_destroy(struct mapped_device *md, bool wait) set_bit(DMF_FREEING, &md->flags); spin_unlock(&_minor_lock); - blk_set_queue_dying(q); + blk_set_queue_dying(md->queue); if (dm_request_based(md) && md->kworker_task) kthread_flush_worker(&md->kworker); -- 2.15.0 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
