[PATCH v2 6/6] mm/list_lru: Simplify the list_lru walk callback function

[Kairui Song <ryncsn@gmail.com>]

From: Kairui Song <kasong@tencent.com>

Now isolation no longer takes the list_lru global node lock, only use the
per-cgroup lock instead. And this lock is inside the list_lru_one being
walked, no longer needed to pass the lock explicitly.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 drivers/android/binder_alloc.c |  7 +++----
 drivers/android/binder_alloc.h |  2 +-
 fs/dcache.c                    |  4 ++--
 fs/gfs2/quota.c                |  2 +-
 fs/inode.c                     |  4 ++--
 fs/nfs/nfs42xattr.c            |  4 ++--
 fs/nfsd/filecache.c            |  5 +----
 fs/xfs/xfs_buf.c               |  2 --
 fs/xfs/xfs_qm.c                |  5 ++---
 include/linux/list_lru.h       |  2 +-
 mm/list_lru.c                  |  2 +-
 mm/workingset.c                | 15 +++++++--------
 mm/zswap.c                     |  4 ++--
 13 files changed, 25 insertions(+), 33 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 86bbe40f4bcd..a738e7745865 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -1047,7 +1047,7 @@ void binder_alloc_vma_close(struct binder_alloc *alloc)
 /**
  * binder_alloc_free_page() - shrinker callback to free pages
  * @item:   item to free
- * @lock:   lock protecting the item
+ * @lru:    list_lru instance of the item
  * @cb_arg: callback argument
  *
  * Called from list_lru_walk() in binder_shrink_scan() to free
@@ -1055,9 +1055,8 @@ void binder_alloc_vma_close(struct binder_alloc *alloc)
  */
 enum lru_status binder_alloc_free_page(struct list_head *item,
 				       struct list_lru_one *lru,
-				       spinlock_t *lock,
 				       void *cb_arg)
-	__must_hold(lock)
+	__must_hold(&lru->lock)
 {
 	struct binder_lru_page *page = container_of(item, typeof(*page), lru);
 	struct binder_alloc *alloc = page->alloc;
@@ -1092,7 +1091,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 
 	list_lru_isolate(lru, item);
 	spin_unlock(&alloc->lock);
-	spin_unlock(lock);
+	spin_unlock(&lru->lock);
 
 	if (vma) {
 		trace_binder_unmap_user_start(alloc, index);
diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index 70387234477e..c02c8ebcb466 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -118,7 +118,7 @@ static inline void binder_selftest_alloc(struct binder_alloc *alloc) {}
 #endif
 enum lru_status binder_alloc_free_page(struct list_head *item,
 				       struct list_lru_one *lru,
-				       spinlock_t *lock, void *cb_arg);
+				       void *cb_arg);
 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 					   size_t data_size,
 					   size_t offsets_size,
diff --git a/fs/dcache.c b/fs/dcache.c
index 0f6b16ba30d0..d7f6866f5f52 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1089,7 +1089,7 @@ void shrink_dentry_list(struct list_head *list)
 }
 
 static enum lru_status dentry_lru_isolate(struct list_head *item,
-		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+		struct list_lru_one *lru, void *arg)
 {
 	struct list_head *freeable = arg;
 	struct dentry	*dentry = container_of(item, struct dentry, d_lru);
@@ -1170,7 +1170,7 @@ long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc)
 }
 
 static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
-		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+		struct list_lru_one *lru, void *arg)
 {
 	struct list_head *freeable = arg;
 	struct dentry	*dentry = container_of(item, struct dentry, d_lru);
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 2e6bc77f4f81..72b48f6f5561 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -149,7 +149,7 @@ static void gfs2_qd_list_dispose(struct list_head *list)
 
 
 static enum lru_status gfs2_qd_isolate(struct list_head *item,
-		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+		struct list_lru_one *lru, void *arg)
 {
 	struct list_head *dispose = arg;
 	struct gfs2_quota_data *qd =
diff --git a/fs/inode.c b/fs/inode.c
index b95d80cb140b..e88c199111ea 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -879,7 +879,7 @@ void invalidate_inodes(struct super_block *sb)
  * with this flag set because they are the inodes that are out of order.
  */
 static enum lru_status inode_lru_isolate(struct list_head *item,
-		struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+		struct list_lru_one *lru, void *arg)
 {
 	struct list_head *freeable = arg;
 	struct inode	*inode = container_of(item, struct inode, i_lru);
@@ -921,7 +921,7 @@ static enum lru_status inode_lru_isolate(struct list_head *item,
 	if (inode_has_buffers(inode) || !mapping_empty(&inode->i_data)) {
 		inode_pin_lru_isolating(inode);
 		spin_unlock(&inode->i_lock);
-		spin_unlock(lru_lock);
+		spin_unlock(&lru->lock);
 		if (remove_inode_buffers(inode)) {
 			unsigned long reap;
 			reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
index b6e3d8f77b91..37d79400e5f4 100644
--- a/fs/nfs/nfs42xattr.c
+++ b/fs/nfs/nfs42xattr.c
@@ -802,7 +802,7 @@ static struct shrinker *nfs4_xattr_large_entry_shrinker;
 
 static enum lru_status
 cache_lru_isolate(struct list_head *item,
-	struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+	struct list_lru_one *lru, void *arg)
 {
 	struct list_head *dispose = arg;
 	struct inode *inode;
@@ -867,7 +867,7 @@ nfs4_xattr_cache_count(struct shrinker *shrink, struct shrink_control *sc)
 
 static enum lru_status
 entry_lru_isolate(struct list_head *item,
-	struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
+	struct list_lru_one *lru, void *arg)
 {
 	struct list_head *dispose = arg;
 	struct nfs4_xattr_bucket *bucket;
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 24e8f1fbcebb..18d82e258853 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -459,7 +459,6 @@ void nfsd_file_net_dispose(struct nfsd_net *nn)
  * nfsd_file_lru_cb - Examine an entry on the LRU list
  * @item: LRU entry to examine
  * @lru: controlling LRU
- * @lock: LRU list lock (unused)
  * @arg: dispose list
  *
  * Return values:
@@ -469,9 +468,7 @@ void nfsd_file_net_dispose(struct nfsd_net *nn)
  */
 static enum lru_status
 nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
-		 spinlock_t *lock, void *arg)
-	__releases(lock)
-	__acquires(lock)
+		 void *arg)
 {
 	struct list_head *head = arg;
 	struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru);
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index aa4dbda7b536..43b914c1f621 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1857,7 +1857,6 @@ static enum lru_status
 xfs_buftarg_drain_rele(
 	struct list_head	*item,
 	struct list_lru_one	*lru,
-	spinlock_t		*lru_lock,
 	void			*arg)
 
 {
@@ -1956,7 +1955,6 @@ static enum lru_status
 xfs_buftarg_isolate(
 	struct list_head	*item,
 	struct list_lru_one	*lru,
-	spinlock_t		*lru_lock,
 	void			*arg)
 {
 	struct xfs_buf		*bp = container_of(item, struct xfs_buf, b_lru);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 665d26990b78..8413ac368042 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -412,9 +412,8 @@ static enum lru_status
 xfs_qm_dquot_isolate(
 	struct list_head	*item,
 	struct list_lru_one	*lru,
-	spinlock_t		*lru_lock,
 	void			*arg)
-		__releases(lru_lock) __acquires(lru_lock)
+		__releases(&lru->lock) __acquires(&lru->lock)
 {
 	struct xfs_dquot	*dqp = container_of(item,
 						struct xfs_dquot, q_lru);
@@ -460,7 +459,7 @@ xfs_qm_dquot_isolate(
 		trace_xfs_dqreclaim_dirty(dqp);
 
 		/* we have to drop the LRU lock to flush the dquot */
-		spin_unlock(lru_lock);
+		spin_unlock(&lru->lock);
 
 		error = xfs_qm_dqflush(dqp, &bp);
 		if (error)
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 10ba9a54d42c..05c166811f6b 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -184,7 +184,7 @@ void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
 			   struct list_head *head);
 
 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item,
-		struct list_lru_one *list, spinlock_t *lock, void *cb_arg);
+		struct list_lru_one *list, void *cb_arg);
 
 /**
  * list_lru_walk_one: walk a @lru, isolating and disposing freeable items.
diff --git a/mm/list_lru.c b/mm/list_lru.c
index 6d1c187d9019..79c2d21504a2 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -295,7 +295,7 @@ __list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
 			break;
 		--*nr_to_walk;
 
-		ret = isolate(item, l, &l->lock, cb_arg);
+		ret = isolate(item, l, cb_arg);
 		switch (ret) {
 		/*
 		 * LRU_RETRY and LRU_REMOVED_RETRY will drop the lru lock,
diff --git a/mm/workingset.c b/mm/workingset.c
index 8c4b6738dcad..4b58ef535a17 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -712,8 +712,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 
 static enum lru_status shadow_lru_isolate(struct list_head *item,
 					  struct list_lru_one *lru,
-					  spinlock_t *lru_lock,
-					  void *arg) __must_hold(lru_lock)
+					  void *arg) __must_hold(lru->lock)
 {
 	struct xa_node *node = container_of(item, struct xa_node, private_list);
 	struct address_space *mapping;
@@ -722,20 +721,20 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	/*
 	 * Page cache insertions and deletions synchronously maintain
 	 * the shadow node LRU under the i_pages lock and the
-	 * lru_lock.  Because the page cache tree is emptied before
-	 * the inode can be destroyed, holding the lru_lock pins any
+	 * &lru->lock. Because the page cache tree is emptied before
+	 * the inode can be destroyed, holding the &lru->lock pins any
 	 * address_space that has nodes on the LRU.
 	 *
 	 * We can then safely transition to the i_pages lock to
 	 * pin only the address_space of the particular node we want
-	 * to reclaim, take the node off-LRU, and drop the lru_lock.
+	 * to reclaim, take the node off-LRU, and drop the &lru->lock.
 	 */
 
 	mapping = container_of(node->array, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
 	if (!xa_trylock(&mapping->i_pages)) {
-		spin_unlock_irq(lru_lock);
+		spin_unlock_irq(&lru->lock);
 		ret = LRU_RETRY;
 		goto out;
 	}
@@ -744,7 +743,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	if (mapping->host != NULL) {
 		if (!spin_trylock(&mapping->host->i_lock)) {
 			xa_unlock(&mapping->i_pages);
-			spin_unlock_irq(lru_lock);
+			spin_unlock_irq(&lru->lock);
 			ret = LRU_RETRY;
 			goto out;
 		}
@@ -753,7 +752,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	list_lru_isolate(lru, item);
 	__dec_node_page_state(virt_to_page(node), WORKINGSET_NODES);
 
-	spin_unlock(lru_lock);
+	spin_unlock(&lru->lock);
 
 	/*
 	 * The nodes should only contain one or more shadow entries,
diff --git a/mm/zswap.c b/mm/zswap.c
index cb37a25fd00c..efad4e941e44 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1096,7 +1096,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
  *    for reclaim by this ratio.
  */
 static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l,
-				       spinlock_t *lock, void *arg)
+				       void *arg)
 {
 	struct zswap_entry *entry = container_of(item, struct zswap_entry, lru);
 	bool *encountered_page_in_swapcache = (bool *)arg;
@@ -1152,7 +1152,7 @@ static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_o
 	 * It's safe to drop the lock here because we return either
 	 * LRU_REMOVED_RETRY or LRU_RETRY.
 	 */
-	spin_unlock(lock);
+	spin_unlock(&l->lock);
 
 	writeback_result = zswap_writeback_entry(entry, swpentry);
 
-- 
2.46.1