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| author | Shaohua Li <shli@kernel.org> | 2013-12-31 11:38:50 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2014-01-30 12:57:25 -0700 |
| commit | f0276924fa35a3607920a58cf5d878212824b951 (patch) | |
| tree | 5759cef09f3ba6b2f206ace779fef298a8b9d7be /include/linux/blk-mq.h | |
| parent | d835502f3dacad1638d516ab156d66f0ba377cf5 (diff) | |
| download | op-kernel-dev-f0276924fa35a3607920a58cf5d878212824b951.zip op-kernel-dev-f0276924fa35a3607920a58cf5d878212824b951.tar.gz | |
blk-mq: Don't reserve a tag for flush request
Reserving a tag (request) for flush to avoid dead lock is a overkill. A
tag is valuable resource. We can track the number of flush requests and
disallow having too many pending flush requests allocated. With this
patch, blk_mq_alloc_request_pinned() could do a busy nop (but not a dead
loop) if too many pending requests are allocated and new flush request
is allocated. But this should not be a problem, too many pending flush
requests are very rare case.
I verified this can fix the deadlock caused by too many pending flush
requests.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blk-mq.h')
| -rw-r--r-- | include/linux/blk-mq.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 161b231..1e8f16f 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -36,12 +36,15 @@ struct blk_mq_hw_ctx { struct list_head page_list; struct blk_mq_tags *tags; + atomic_t pending_flush; + unsigned long queued; unsigned long run; #define BLK_MQ_MAX_DISPATCH_ORDER 10 unsigned long dispatched[BLK_MQ_MAX_DISPATCH_ORDER]; unsigned int queue_depth; + unsigned int reserved_tags; unsigned int numa_node; unsigned int cmd_size; /* per-request extra data */ |
