diff options
| author | Tejun Heo <tj@kernel.org> | 2012-03-05 22:15:26 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-03-06 21:27:24 +0100 |
| commit | f6e8d01bee036460e03bd4f6a79d014f98ba712e (patch) | |
| tree | acaaab3667e0450f0f05464426c3540c89ce4e18 /block | |
| parent | block: ioc_task_link() can't fail (diff) | |
| download | linux-f6e8d01bee036460e03bd4f6a79d014f98ba712e.tar.xz linux-f6e8d01bee036460e03bd4f6a79d014f98ba712e.zip | |
block: add io_context->active_ref
Currently ioc->nr_tasks is used to decide two things - whether an ioc
is done issuing IOs and whether it's shared by multiple tasks. This
patch separate out the first into ioc->active_ref, which is acquired
and released using {get|put}_io_context_active() respectively.
This will be used to associate bio's with a given task. This patch
doesn't introduce any visible behavior change.
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')
| -rw-r--r-- | block/blk-ioc.c | 36 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 4 |
2 files changed, 27 insertions, 13 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 10928740b5da..439ec21fd787 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -149,20 +149,20 @@ void put_io_context(struct io_context *ioc) } EXPORT_SYMBOL(put_io_context); -/* Called by the exiting task */ -void exit_io_context(struct task_struct *task) +/** + * put_io_context_active - put active reference on ioc + * @ioc: ioc of interest + * + * Undo get_io_context_active(). If active reference reaches zero after + * put, @ioc can never issue further IOs and ioscheds are notified. + */ +void put_io_context_active(struct io_context *ioc) { - struct io_context *ioc; - struct io_cq *icq; struct hlist_node *n; unsigned long flags; + struct io_cq *icq; - task_lock(task); - ioc = task->io_context; - task->io_context = NULL; - task_unlock(task); - - if (!atomic_dec_and_test(&ioc->nr_tasks)) { + if (!atomic_dec_and_test(&ioc->active_ref)) { put_io_context(ioc); return; } @@ -191,6 +191,20 @@ retry: put_io_context(ioc); } +/* Called by the exiting task */ +void exit_io_context(struct task_struct *task) +{ + struct io_context *ioc; + + task_lock(task); + ioc = task->io_context; + task->io_context = NULL; + task_unlock(task); + + atomic_dec(&ioc->nr_tasks); + put_io_context_active(ioc); +} + /** * ioc_clear_queue - break any ioc association with the specified queue * @q: request_queue being cleared @@ -223,7 +237,7 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node) /* initialize */ atomic_long_set(&ioc->refcount, 1); - atomic_set(&ioc->nr_tasks, 1); + atomic_set(&ioc->active_ref, 1); spin_lock_init(&ioc->lock); INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH); INIT_HLIST_HEAD(&ioc->icq_list); diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 9e386d9bcb79..9a4eac490e0b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1865,7 +1865,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) * task has exited, don't wait */ cic = cfqd->active_cic; - if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks)) + if (!cic || !atomic_read(&cic->icq.ioc->active_ref)) return; /* @@ -2841,7 +2841,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) enable_idle = 0; - else if (!atomic_read(&cic->icq.ioc->nr_tasks) || + else if (!atomic_read(&cic->icq.ioc->active_ref) || !cfqd->cfq_slice_idle || (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) enable_idle = 0; |