Subject: [PATCH 9/9] zsmalloc: remove the zsmalloc file system

From: Christoph Hellwig <[email-masked]>
Date: Tue, 9 Mar 2021 16:53:48 +0100

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <[email-masked]>
---
 mm/zsmalloc.c | 48 +++---------------------------------------------
 1 file changed, 3 insertions(+), 45 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index a6449a2ad861de..a7d2f471935447 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -41,6 +41,7 @@
 #include <linux/slab.h>
 #include <linux/pgtable.h>
 #include <asm/tlbflush.h>
+#include <linux/anon_inodes.h>
 #include <linux/cpumask.h>
 #include <linux/cpu.h>
 #include <linux/vmalloc.h>
@@ -176,10 +177,6 @@ struct zs_size_stat {
 static struct dentry *zs_stat_root;
 #endif
 
-#ifdef CONFIG_COMPACTION
-static struct vfsmount *zsmalloc_mnt;
-#endif
-
 /*
  * We assign a page to ZS_ALMOST_EMPTY fullness group when:
  *	n <= N / f, where
@@ -308,8 +305,6 @@ static void kick_deferred_free(struct zs_pool *pool);
 static void init_deferred_free(struct zs_pool *pool);
 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
 #else
-static int zsmalloc_mount(void) { return 0; }
-static void zsmalloc_unmount(void) {}
 static int zs_register_migration(struct zs_pool *pool) { return 0; }
 static void zs_unregister_migration(struct zs_pool *pool) {}
 static void migrate_lock_init(struct zspage *zspage) {}
@@ -1751,33 +1746,6 @@ static void lock_zspage(struct zspage *zspage)
 	} while ((page = get_next_page(page)) != NULL);
 }
 
-static int zs_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, ZSMALLOC_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type zsmalloc_fs = {
-	.name		= "zsmalloc",
-	.init_fs_context = zs_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
-static int zsmalloc_mount(void)
-{
-	int ret = 0;
-
-	zsmalloc_mnt = kern_mount(&zsmalloc_fs);
-	if (IS_ERR(zsmalloc_mnt))
-		ret = PTR_ERR(zsmalloc_mnt);
-
-	return ret;
-}
-
-static void zsmalloc_unmount(void)
-{
-	kern_unmount(zsmalloc_mnt);
-}
-
 static void migrate_lock_init(struct zspage *zspage)
 {
 	rwlock_init(&zspage->lock);
@@ -2086,7 +2054,7 @@ static const struct address_space_operations zsmalloc_aops = {
 
 static int zs_register_migration(struct zs_pool *pool)
 {
-	pool->inode = alloc_anon_inode_sb(zsmalloc_mnt->mnt_sb);
+	pool->inode = alloc_anon_inode();
 	if (IS_ERR(pool->inode)) {
 		pool->inode = NULL;
 		return 1;
@@ -2506,14 +2474,10 @@ static int __init zs_init(void)
 {
 	int ret;
 
-	ret = zsmalloc_mount();
-	if (ret)
-		goto out;
-
 	ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare",
 				zs_cpu_prepare, zs_cpu_dead);
 	if (ret)
-		goto hp_setup_fail;
+		return ret;
 
 #ifdef CONFIG_ZPOOL
 	zpool_register_driver(&zs_zpool_driver);
@@ -2522,11 +2486,6 @@ static int __init zs_init(void)
 	zs_stat_init();
 
 	return 0;
-
-hp_setup_fail:
-	zsmalloc_unmount();
-out:
-	return ret;
 }
 
 static void __exit zs_exit(void)
@@ -2534,7 +2493,6 @@ static void __exit zs_exit(void)
 #ifdef CONFIG_ZPOOL
 	zpool_unregister_driver(&zs_zpool_driver);
 #endif
-	zsmalloc_unmount();
 	cpuhp_remove_state(CPUHP_MM_ZS_PREPARE);
 
 	zs_stat_exit();
-- 
2.30.1