On 01/11/2018 03:12 AM, Mike Snitzer wrote: > 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 <snitzer@xxxxxxxxxx> > --- > 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); > As mentioned in the other mail, maybe one should consider using a wrapper function for 'add_disk()' to avoid having to set the magic queue flag. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
