[PATCH 1/2] percpu_counter: Rename __percpu_counter_add to percpu_counter_add_batch

[Nikolay Borisov <nborisov@suse.com>]

252e0ba6b77d ("lib: percpu_counter variable batch") added a batched version
of percpu_counter_add. However, one problem with this patch is the fact that it
overloads the meaning of double underscore, which in kernel-land are taken
to implicitly mean there is no preempt protection for the API. Currently, in
both !SMP and SMP configs percpu_counter_add calls __percpu_counter_add which
is preempt safe due to explicit calls to preempt_disable. This state of play
creates the false sense that __percpu_counter_add is less SMP-safe than
percpu_counter_add. They are both identical irrespective of CONFIG_SNMP value.
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.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/disk-io.c             | 4 ++--
 fs/btrfs/extent_io.c           | 2 +-
 fs/btrfs/inode.c               | 4 ++--
 fs/xfs/xfs_mount.c             | 4 ++--
 include/linux/backing-dev.h    | 2 +-
 include/linux/blk-cgroup.h     | 6 +++---
 include/linux/mman.h           | 2 +-
 include/linux/percpu_counter.h | 7 ++++---
 include/net/inet_frag.h        | 4 ++--
 lib/flex_proportions.c         | 6 +++---
 lib/percpu_counter.c           | 4 ++--
 11 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2eaa1b1db08d..9fc37d6641cd 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1255,7 +1255,7 @@ void clean_tree_block(struct btrfs_fs_info *fs_info,
 		btrfs_assert_tree_locked(buf);
 
 		if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &buf->bflags)) {
-			__percpu_counter_add(&fs_info->dirty_metadata_bytes,
+			percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
 					     -buf->len,
 					     fs_info->dirty_metadata_batch);
 			/* ugh, clear_extent_buffer_dirty needs to lock the page */
@@ -4048,7 +4048,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
 			buf->start, transid, fs_info->generation);
 	was_dirty = set_extent_buffer_dirty(buf);
 	if (!was_dirty)
-		__percpu_counter_add(&fs_info->dirty_metadata_bytes,
+		percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
 				     buf->len,
 				     fs_info->dirty_metadata_batch);
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d3619e010005..a1c303f27699 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3597,7 +3597,7 @@ lock_extent_buffer_for_io(struct extent_buffer *eb,
 		set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
 		spin_unlock(&eb->refs_lock);
 		btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
-		__percpu_counter_add(&fs_info->dirty_metadata_bytes,
+		percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
 				     -eb->len,
 				     fs_info->dirty_metadata_batch);
 		ret = 1;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ef3c98c527c1..fa138217219e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1766,7 +1766,7 @@ static void btrfs_set_bit_hook(struct inode *inode,
 		if (btrfs_is_testing(fs_info))
 			return;
 
-		__percpu_counter_add(&fs_info->delalloc_bytes, len,
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, len,
 				     fs_info->delalloc_batch);
 		spin_lock(&BTRFS_I(inode)->lock);
 		BTRFS_I(inode)->delalloc_bytes += len;
@@ -1840,7 +1840,7 @@ static void btrfs_clear_bit_hook(struct btrfs_inode *inode,
 					&inode->vfs_inode,
 					state->start, len);
 
-		__percpu_counter_add(&fs_info->delalloc_bytes, -len,
+		percpu_counter_add_batch(&fs_info->delalloc_bytes, -len,
 				     fs_info->delalloc_batch);
 		spin_lock(&inode->lock);
 		inode->delalloc_bytes -= len;
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 2eaf81859166..7147d4a8d207 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1209,7 +1209,7 @@ xfs_mod_icount(
 	struct xfs_mount	*mp,
 	int64_t			delta)
 {
-	__percpu_counter_add(&mp->m_icount, delta, XFS_ICOUNT_BATCH);
+	percpu_counter_add_batch(&mp->m_icount, delta, XFS_ICOUNT_BATCH);
 	if (__percpu_counter_compare(&mp->m_icount, 0, XFS_ICOUNT_BATCH) < 0) {
 		ASSERT(0);
 		percpu_counter_add(&mp->m_icount, -delta);
@@ -1288,7 +1288,7 @@ xfs_mod_fdblocks(
 	else
 		batch = XFS_FDBLOCKS_BATCH;
 
-	__percpu_counter_add(&mp->m_fdblocks, delta, batch);
+	percpu_counter_add_batch(&mp->m_fdblocks, delta, batch);
 	if (__percpu_counter_compare(&mp->m_fdblocks, mp->m_alloc_set_aside,
 				     XFS_FDBLOCKS_BATCH) >= 0) {
 		/* we had space! */
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 557d84063934..ace73f96eb1e 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -66,7 +66,7 @@ static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
 static inline void __add_wb_stat(struct bdi_writeback *wb,
 				 enum wb_stat_item item, s64 amount)
 {
-	__percpu_counter_add(&wb->stat[item], amount, WB_STAT_BATCH);
+	percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
 }
 
 static inline void __inc_wb_stat(struct bdi_writeback *wb,
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 01b62e7bac74..7104bea8dab1 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -518,7 +518,7 @@ static inline void blkg_stat_exit(struct blkg_stat *stat)
  */
 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 {
-	__percpu_counter_add(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
+	percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
 }
 
 /**
@@ -597,14 +597,14 @@ static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 	else
 		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
 
-	__percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
+	percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
 
 	if (op_is_sync(op))
 		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
 	else
 		cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
 
-	__percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
+	percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
 }
 
 /**
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 634c4c51fe3a..c8367041fafd 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -22,7 +22,7 @@ unsigned long vm_memory_committed(void);
 
 static inline void vm_acct_memory(long pages)
 {
-	__percpu_counter_add(&vm_committed_as, pages, vm_committed_as_batch);
+	percpu_counter_add_batch(&vm_committed_as, pages, vm_committed_as_batch);
 }
 
 static inline void vm_unacct_memory(long pages)
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index 84a109449610..ec065387f443 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -39,7 +39,8 @@ int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
 
 void percpu_counter_destroy(struct percpu_counter *fbc);
 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
-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 __percpu_counter_sum(struct percpu_counter *fbc);
 int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
 
@@ -50,7 +51,7 @@ static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
 
 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
 {
-	__percpu_counter_add(fbc, amount, percpu_counter_batch);
+	percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
 }
 
 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
@@ -136,7 +137,7 @@ percpu_counter_add(struct percpu_counter *fbc, s64 amount)
 }
 
 static inline void
-__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
 {
 	percpu_counter_add(fbc, amount);
 }
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 5894730ec82a..5932e6de8fc0 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -154,12 +154,12 @@ static inline int frag_mem_limit(struct netns_frags *nf)
 
 static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
 {
-	__percpu_counter_add(&nf->mem, -i, frag_percpu_counter_batch);
+	percpu_counter_add_batch(&nf->mem, -i, frag_percpu_counter_batch);
 }
 
 static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
 {
-	__percpu_counter_add(&nf->mem, i, frag_percpu_counter_batch);
+	percpu_counter_add_batch(&nf->mem, i, frag_percpu_counter_batch);
 }
 
 static inline unsigned int sum_frag_mem_limit(struct netns_frags *nf)
diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c
index a71cf1bdd4c9..2cc1f94e03a1 100644
--- a/lib/flex_proportions.c
+++ b/lib/flex_proportions.c
@@ -207,7 +207,7 @@ static void fprop_reflect_period_percpu(struct fprop_global *p,
 		if (val < (nr_cpu_ids * PROP_BATCH))
 			val = percpu_counter_sum(&pl->events);
 
-		__percpu_counter_add(&pl->events,
+		percpu_counter_add_batch(&pl->events,
 			-val + (val >> (period-pl->period)), PROP_BATCH);
 	} else
 		percpu_counter_set(&pl->events, 0);
@@ -219,7 +219,7 @@ static void fprop_reflect_period_percpu(struct fprop_global *p,
 void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
 {
 	fprop_reflect_period_percpu(p, pl);
-	__percpu_counter_add(&pl->events, 1, PROP_BATCH);
+	percpu_counter_add_batch(&pl->events, 1, PROP_BATCH);
 	percpu_counter_add(&p->events, 1);
 }
 
@@ -267,6 +267,6 @@ void __fprop_inc_percpu_max(struct fprop_global *p,
 			return;
 	} else
 		fprop_reflect_period_percpu(p, pl);
-	__percpu_counter_add(&pl->events, 1, PROP_BATCH);
+	percpu_counter_add_batch(&pl->events, 1, PROP_BATCH);
 	percpu_counter_add(&p->events, 1);
 }
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 9c21000df0b5..8ee7e5ec21be 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
-- 
2.7.4