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authorTejun Heo <tj@kernel.org>2012-03-05 13:15:26 -0800
committerJens Axboe <axboe@kernel.dk>2012-03-06 21:27:24 +0100
commitf6e8d01bee036460e03bd4f6a79d014f98ba712e (patch)
treeacaaab3667e0450f0f05464426c3540c89ce4e18 /block/blk-ioc.c
parent3d48749d93a3dce732dd30a14002ab90ec4355f3 (diff)
downloadlinux-linaro-stable-f6e8d01bee036460e03bd4f6a79d014f98ba712e.tar.gz
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/blk-ioc.c')
-rw-r--r--block/blk-ioc.c36
1 files changed, 25 insertions, 11 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);