[Devel] [PATCH v14 08/18] fs: consolidate {nr, free}_cached_objects args in shrink_control

[Vladimir Davydov]

We are going to make the FS shrinker memcg-aware. To achieve that, we
will have to pass the memcg to scan to the nr_cached_objects and
free_cached_objects VFS methods, which currently take only the NUMA node
to scan. Since the shrink_control structure already holds the node, and
the memcg to scan will be added to it as we introduce memcg-aware
vmscan, let us consolidate the methods' arguments in this structure to
keep things clean.

Thanks to David Chinner for the tip.

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
Cc: Glauber Costa <glommer at openvz.org>
Cc: Dave Chinner <dchinner at redhat.com>
Cc: Al Viro <viro at zeniv.linux.org.uk>
---
 fs/super.c         |   12 ++++++------
 fs/xfs/xfs_super.c |    7 +++----
 include/linux/fs.h |    6 ++++--
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/fs/super.c b/fs/super.c
index 13c4c92..9084c3d 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -76,7 +76,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
 		return SHRINK_STOP;
 
 	if (sb->s_op->nr_cached_objects)
-		fs_objects = sb->s_op->nr_cached_objects(sb, sc->nid);
+		fs_objects = sb->s_op->nr_cached_objects(sb, sc);
 
 	inodes = list_lru_shrink_count(&sb->s_inode_lru, sc);
 	dentries = list_lru_shrink_count(&sb->s_dentry_lru, sc);
@@ -96,9 +96,10 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
 	sc->nr_to_scan = inodes;
 	freed += prune_icache_sb(sb, sc);
 
-	if (fs_objects)
-		freed += sb->s_op->free_cached_objects(sb, fs_objects,
-						       sc->nid);
+	if (fs_objects) {
+		sc->nr_to_scan = fs_objects;
+		freed += sb->s_op->free_cached_objects(sb, sc);
+	}
 
 	drop_super(sb);
 	return freed;
@@ -116,8 +117,7 @@ static unsigned long super_cache_count(struct shrinker *shrink,
 		return 0;
 
 	if (sb->s_op && sb->s_op->nr_cached_objects)
-		total_objects = sb->s_op->nr_cached_objects(sb,
-						 sc->nid);
+		total_objects = sb->s_op->nr_cached_objects(sb, sc);
 
 	total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc);
 	total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc);
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index f317488..28d0697 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1524,7 +1524,7 @@ xfs_fs_mount(
 static long
 xfs_fs_nr_cached_objects(
 	struct super_block	*sb,
-	int			nid)
+	struct shrink_control	*sc)
 {
 	return xfs_reclaim_inodes_count(XFS_M(sb));
 }
@@ -1532,10 +1532,9 @@ xfs_fs_nr_cached_objects(
 static long
 xfs_fs_free_cached_objects(
 	struct super_block	*sb,
-	long			nr_to_scan,
-	int			nid)
+	struct shrink_control	*sc)
 {
-	return xfs_reclaim_inodes_nr(XFS_M(sb), nr_to_scan);
+	return xfs_reclaim_inodes_nr(XFS_M(sb), sc->nr_to_scan);
 }
 
 static const struct super_operations xfs_super_operations = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 121f11f..aef5e6b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1619,8 +1619,10 @@ struct super_operations {
 	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
 #endif
 	int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
-	long (*nr_cached_objects)(struct super_block *, int);
-	long (*free_cached_objects)(struct super_block *, long, int);
+	long (*nr_cached_objects)(struct super_block *,
+				  struct shrink_control *);
+	long (*free_cached_objects)(struct super_block *,
+				    struct shrink_control *);
 };
 
 /*
-- 
1.7.10.4