percpu_ida: add percpu_ida_for_each_free

Add a new API to iterate free ids. blk-mq-tag will use it.

Note, this doesn't guarantee to iterate all free ids restrictly. Caller
should be aware of this. blk-mq uses it to do sanity check for request
timedout, so can tolerate the limitation.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/percpu_ida.h b/include/linux/percpu_ida.h
index 56c14033e7e79aa32c66f3580e19c9229cca7785..63510ae6f93388b024b9991bf7a63fcf8d087313 100644 (file)
--- a/include/linux/percpu_ida.h
+++ b/include/linux/percpu_ida.h
@@ -73,4 +73,8 @@ static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags
                IDA_DEFAULT_PCPU_BATCH_MOVE);
 }
 
+typedef int (*percpu_ida_cb)(unsigned, void *);
+int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
+       void *data);
+
 #endif /* __PERCPU_IDA_H__ */

diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c
index a601d4259e13267b45a8023cb62e63fc15398301..0f51c1b556cf2fbd9758fd0e0a28ac9ccfee6a40 100644 (file)
--- a/lib/percpu_ida.c
+++ b/lib/percpu_ida.c
@@ -327,3 +327,47 @@ err:
        return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(__percpu_ida_init);
+
+/**
+ * percpu_ida_for_each_free - iterate free ids of a pool
+ * @pool: pool to iterate
+ * @fn: interate callback function
+ * @data: parameter for @fn
+ *
+ * Note, this doesn't guarantee to iterate all free ids restrictly. Some free
+ * ids might be missed, some might be iterated duplicated, and some might
+ * be iterated and not free soon.
+ */
+int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
+       void *data)
+{
+       unsigned long flags;
+       struct percpu_ida_cpu *remote;
+       unsigned cpu, i, err = 0;
+
+       local_irq_save(flags);
+       for_each_possible_cpu(cpu) {
+               remote = per_cpu_ptr(pool->tag_cpu, cpu);
+               spin_lock(&remote->lock);
+               for (i = 0; i < remote->nr_free; i++) {
+                       err = fn(remote->freelist[i], data);
+                       if (err)
+                               break;
+               }
+               spin_unlock(&remote->lock);
+               if (err)
+                       goto out;
+       }
+
+       spin_lock(&pool->lock);
+       for (i = 0; i < pool->nr_free; i++) {
+               err = fn(pool->freelist[i], data);
+               if (err)
+                       break;
+       }
+       spin_unlock(&pool->lock);
+out:
+       local_irq_restore(flags);
+       return err;
+}
+EXPORT_SYMBOL_GPL(percpu_ida_for_each_free);