DM is 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 using add_disk_no_queue_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). 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_ blk_register_queue() was called via add_disk()). 2) call elv_register_queue() to get .request_fn request-based DM device's "iosched" 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 dm_setup_md_queue() calls blk_register_queue(). 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 provided by the request_queue). Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Tested-by: Ming Lei <ming.lei@xxxxxxxxxx> --- drivers/md/dm-rq.c | 9 --------- drivers/md/dm.c | 11 ++++++++++- 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 9d32f25489c2..c28357f5cb0e 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -713,8 +713,6 @@ int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t) return error; } - elv_register_queue(md->queue); - return 0; } @@ -812,15 +810,8 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) } 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..8c26bfc35335 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1761,7 +1761,7 @@ static struct mapped_device *alloc_dev(int minor) goto bad; md->dax_dev = dax_dev; - add_disk(md->disk); + add_disk_no_queue_reg(md->disk); format_dev_t(md->name, MKDEV(_major, minor)); md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0); @@ -2021,6 +2021,7 @@ 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) { @@ -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; } -- 2.15.0
