diff options
author | Mike Snitzer <snitzer@redhat.com> | 2018-01-08 22:01:13 -0500 |
---|---|---|
committer | Jason Liu <jason.hui.liu@nxp.com> | 2019-02-12 10:33:25 +0800 |
commit | f5ff070430bafa1540f7268476eacae30bf7ef14 (patch) | |
tree | 5ffb661af507bf3bb88f4ed66adf89f8d17246bb /block/blk-sysfs.c | |
parent | 9ab3834a3871936dcaba346d3780fcdfabd6ae88 (diff) |
block: allow gendisk's request_queue registration to be deferred
Since I can remember DM has forced the block layer to allow the
allocation and initialization of the request_queue to be distinct
operations. Reason for this is block/genhd.c:add_disk() has requires
that the request_queue (and associated bdi) be tied to the gendisk
before add_disk() is called -- because add_disk() also deals with
exposing the request_queue via blk_register_queue().
DM's dynamic creation of arbitrary device types (and associated
request_queue types) requires the DM device's gendisk be available so
that DM table loads can establish a master/slave relationship with
subordinate devices that are referenced by loaded DM tables -- using
bd_link_disk_holder(). But until these DM tables, and their associated
subordinate devices, are known DM cannot know what type of request_queue
it needs -- nor what its queue_limits should be.
This chicken and egg scenario has created all manner of problems for DM
and, at times, the block layer.
Summary of changes:
- Add device_add_disk_no_queue_reg() and add_disk_no_queue_reg() variant
that drivers may use to add a disk without also calling
blk_register_queue(). Driver must call blk_register_queue() once its
request_queue is fully initialized.
- Return early from blk_unregister_queue() if QUEUE_FLAG_REGISTERED
is not set. It won't be set if driver used add_disk_no_queue_reg()
but driver encounters an error and must del_gendisk() before calling
blk_register_queue().
- Export blk_register_queue().
These changes allow DM to use add_disk_no_queue_reg() to anchor its
gendisk as the "master" for master/slave relationships DM must establish
with subordinate devices referenced in DM tables that get loaded. Once
all "slave" devices for a DM device are known its request_queue can be
properly initialized and then advertised via sysfs -- important
improvement being that no request_queue resource initialization
performed by blk_register_queue() is missed for DM devices anymore.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit fa70d2e2c4a0a54ced98260c6a176cc94c876d27)
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r-- | block/blk-sysfs.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 4415cd268e4c..adfdb7d50598 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -924,6 +924,7 @@ unlock: mutex_unlock(&q->sysfs_lock); return ret; } +EXPORT_SYMBOL_GPL(blk_register_queue); void blk_unregister_queue(struct gendisk *disk) { @@ -932,6 +933,10 @@ void blk_unregister_queue(struct gendisk *disk) if (WARN_ON(!q)) return; + /* Return early if disk->queue was never registered. */ + if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags)) + return; + /* * Protect against the 'queue' kobj being accessed * while/after it is removed. |