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block: misc ioc cleanups 

* int return from put_io_context() wasn't used by anybody.  Make it
  return void like other put functions and docbook-fy the function
  comment.

* Reorder dummy declarations for !CONFIG_BLOCK case a bit.

* Make alloc_ioc_context() use __GFP_ZERO allocation, take init out of
  if block and drop 0'ing.

* Docbook-fy current_io_context() comment.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Tejun Heo 2011-12-14 00:33:37 +01:00 committed by Jens Axboe
parent a73f730d01
commit 42ec57a8f6
2 changed files with 39 additions and 45 deletions
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72
block/blk-ioc.c
View File

@ -27,26 +27,28 @@ static void cfq_dtor(struct io_context *ioc)
}
}
/*
* IO Context helper functions. put_io_context() returns 1 if there are no
* more users of this io context, 0 otherwise.
/**
* put_io_context - put a reference of io_context
* @ioc: io_context to put
*
* Decrement reference count of @ioc and release it if the count reaches
* zero.
*/
int put_io_context(struct io_context *ioc)
void put_io_context(struct io_context *ioc)
{
if (ioc == NULL)
return 1;
return;
BUG_ON(atomic_long_read(&ioc->refcount) == 0);
BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
if (atomic_long_dec_and_test(&ioc->refcount)) {
rcu_read_lock();
cfq_dtor(ioc);
rcu_read_unlock();
if (!atomic_long_dec_and_test(&ioc->refcount))
return;
kmem_cache_free(iocontext_cachep, ioc);
return 1;
}
return 0;
rcu_read_lock();
cfq_dtor(ioc);
rcu_read_unlock();
kmem_cache_free(iocontext_cachep, ioc);
}
EXPORT_SYMBOL(put_io_context);
@ -84,33 +86,31 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
{
struct io_context *ioc;
ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
if (ioc) {
atomic_long_set(&ioc->refcount, 1);
atomic_set(&ioc->nr_tasks, 1);
spin_lock_init(&ioc->lock);
ioc->ioprio_changed = 0;
ioc->ioprio = 0;
ioc->last_waited = 0; /* doesn't matter... */
ioc->nr_batch_requests = 0; /* because this is 0 */
INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
INIT_HLIST_HEAD(&ioc->cic_list);
ioc->ioc_data = NULL;
#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
ioc->cgroup_changed = 0;
#endif
}
ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
node);
if (unlikely(!ioc))
return NULL;
/* initialize */
atomic_long_set(&ioc->refcount, 1);
atomic_set(&ioc->nr_tasks, 1);
spin_lock_init(&ioc->lock);
INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
INIT_HLIST_HEAD(&ioc->cic_list);
return ioc;
}
/*
* If the current task has no IO context then create one and initialise it.
* Otherwise, return its existing IO context.
/**
* current_io_context - get io_context of %current
* @gfp_flags: allocation flags, used if allocation is necessary
* @node: allocation node, used if allocation is necessary
*
* This returned IO context doesn't have a specifically elevated refcount,
* but since the current task itself holds a reference, the context can be
* used in general code, so long as it stays within `current` context.
* Return io_context of %current. If it doesn't exist, it is created with
* @gfp_flags and @node. The returned io_context does NOT have its
* reference count incremented. Because io_context is exited only on task
* exit, %current can be sure that the returned io_context is valid and
* alive as long as it is executing.
*/
struct io_context *current_io_context(gfp_t gfp_flags, int node)
{

12
include/linux/iocontext.h
View File

@ -76,20 +76,14 @@ static inline struct io_context *ioc_task_link(struct io_context *ioc)
struct task_struct;
#ifdef CONFIG_BLOCK
int put_io_context(struct io_context *ioc);
void put_io_context(struct io_context *ioc);
void exit_io_context(struct task_struct *task);
struct io_context *get_io_context(gfp_t gfp_flags, int node);
struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
#else
static inline void exit_io_context(struct task_struct *task)
{
}
struct io_context;
static inline int put_io_context(struct io_context *ioc)
{
return 1;
}
static inline void put_io_context(struct io_context *ioc) { }
static inline void exit_io_context(struct task_struct *task) { }
#endif
#endif