percpu_counter: Rename __percpu_counter_add to percpu_counter_add_batch

Currently, percpu_counter_add is a wrapper around __percpu_counter_add
which is preempt safe due to explicit calls to preempt_disable.  Given
how __ prefix is used in percpu related interfaces, the naming
unfortunately creates the false sense that __percpu_counter_add is
less safe than percpu_counter_add.  In terms of context-safety,
they're equivalent.  The only difference is that the __ version takes
a batch parameter.

Make this a bit more explicit by just renaming __percpu_counter_add to
percpu_counter_add_batch.

This patch doesn't cause any functional changes.

tj: Minor updates to patch description for clarity.  Cosmetic
    indentation updates.

Signed-off-by: Nikolay Borisov <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: [email protected]
Cc: "David S. Miller" <[email protected]>
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 9c21000..8ee7e5e 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -72,7 +72,7 @@ void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
 }
 EXPORT_SYMBOL(percpu_counter_set);
 
-void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
 {
 	s64 count;
 
@@ -89,7 +89,7 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
 	}
 	preempt_enable();
 }
-EXPORT_SYMBOL(__percpu_counter_add);
+EXPORT_SYMBOL(percpu_counter_add_batch);
 
 /*
  * Add up all the per-cpu counts, return the result.  This is a more accurate