diff options
| author | Tejun Heo <tj@kernel.org> | 2012-03-05 22:14:58 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-03-06 21:27:21 +0100 |
| commit | d732580b4eb31553c63744a47d590f770cafb8f0 (patch) | |
| tree | ea4e8e21df1b639603693e6f5fdfc5a620cd8737 /block/blk-core.c | |
| parent | elevator: make elevator_init_fn() return 0/-errno (diff) | |
| download | linux-d732580b4eb31553c63744a47d590f770cafb8f0.tar.xz linux-d732580b4eb31553c63744a47d590f770cafb8f0.zip | |
block: implement blk_queue_bypass_start/end()
Rename and extend elv_queisce_start/end() to
blk_queue_bypass_start/end() which are exported and supports nesting
via @q->bypass_depth. Also add blk_queue_bypass() to test bypass
state.
This will be further extended and used for blkio_group management.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index fccb25021121..98ddef430093 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -410,6 +410,42 @@ void blk_drain_queue(struct request_queue *q, bool drain_all) } /** + * blk_queue_bypass_start - enter queue bypass mode + * @q: queue of interest + * + * In bypass mode, only the dispatch FIFO queue of @q is used. This + * function makes @q enter bypass mode and drains all requests which were + * issued before. On return, it's guaranteed that no request has ELVPRIV + * set. + */ +void blk_queue_bypass_start(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + q->bypass_depth++; + queue_flag_set(QUEUE_FLAG_BYPASS, q); + spin_unlock_irq(q->queue_lock); + + blk_drain_queue(q, false); +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_start); + +/** + * blk_queue_bypass_end - leave queue bypass mode + * @q: queue of interest + * + * Leave bypass mode and restore the normal queueing behavior. + */ +void blk_queue_bypass_end(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + if (!--q->bypass_depth) + queue_flag_clear(QUEUE_FLAG_BYPASS, q); + WARN_ON_ONCE(q->bypass_depth < 0); + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_end); + +/** * blk_cleanup_queue - shutdown a request queue * @q: request queue to shutdown * @@ -862,8 +898,7 @@ retry: * Also, lookup icq while holding queue_lock. If it doesn't exist, * it will be created after releasing queue_lock. */ - if (blk_rq_should_init_elevator(bio) && - !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags)) { + if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) { rw_flags |= REQ_ELVPRIV; rl->elvpriv++; if (et->icq_cache && ioc) |