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| author | Dan Williams <dan.j.williams@intel.com> | 2015-10-21 13:20:12 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-10-21 14:43:41 -0600 |
| commit | 3ef28e83ab15799742e55fd13243a5f678b04242 (patch) | |
| tree | e594552aaeaafed8468ae96e54992cf1697a1fc7 /include/linux/blkdev.h | |
| parent | 4cfc766e07a5ed709a9d5289c8644fe78e9f24de (diff) | |
| download | lwn-3ef28e83ab15799742e55fd13243a5f678b04242.tar.gz lwn-3ef28e83ab15799742e55fd13243a5f678b04242.zip | |
block: generic request_queue reference counting
Allow pmem, and other synchronous/bio-based block drivers, to fallback
on a per-cpu reference count managed by the core for tracking queue
live/dead state.
The existing per-cpu reference count for the blk_mq case is promoted to
be used in all block i/o scenarios. This involves initializing it by
default, waiting for it to drop to zero at exit, and holding a live
reference over the invocation of q->make_request_fn() in
generic_make_request(). The blk_mq code continues to take its own
reference per blk_mq request and retains the ability to freeze the
queue, but the check that the queue is frozen is moved to
generic_make_request().
This fixes crash signatures like the following:
BUG: unable to handle kernel paging request at ffff880140000000
[..]
Call Trace:
[<ffffffff8145e8bf>] ? copy_user_handle_tail+0x5f/0x70
[<ffffffffa004e1e0>] pmem_do_bvec.isra.11+0x70/0xf0 [nd_pmem]
[<ffffffffa004e331>] pmem_make_request+0xd1/0x200 [nd_pmem]
[<ffffffff811c3162>] ? mempool_alloc+0x72/0x1a0
[<ffffffff8141f8b6>] generic_make_request+0xd6/0x110
[<ffffffff8141f966>] submit_bio+0x76/0x170
[<ffffffff81286dff>] submit_bh_wbc+0x12f/0x160
[<ffffffff81286e62>] submit_bh+0x12/0x20
[<ffffffff813395bd>] jbd2_write_superblock+0x8d/0x170
[<ffffffff8133974d>] jbd2_mark_journal_empty+0x5d/0x90
[<ffffffff813399cb>] jbd2_journal_destroy+0x24b/0x270
[<ffffffff810bc4ca>] ? put_pwq_unlocked+0x2a/0x30
[<ffffffff810bc6f5>] ? destroy_workqueue+0x225/0x250
[<ffffffff81303494>] ext4_put_super+0x64/0x360
[<ffffffff8124ab1a>] generic_shutdown_super+0x6a/0xf0
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blkdev.h')
| -rw-r--r-- | include/linux/blkdev.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 60669c20190f..3e0465257d68 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -450,7 +450,7 @@ struct request_queue { #endif struct rcu_head rcu_head; wait_queue_head_t mq_freeze_wq; - struct percpu_ref mq_usage_counter; + struct percpu_ref q_usage_counter; struct list_head all_q_node; struct blk_mq_tag_set *tag_set; |