[PATCH 12/12] swap: move swap_info_struct to mm/swap.h

[Christoph Hellwig <hch@lst.de>]

swap_info_struct is now internal to the MM subsystem, so remove it from
the public header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/swap.h | 98 +-------------------------------------------
 mm/swap.h            | 92 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+), 96 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 95237ee065c2..31eef9b74949 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -16,9 +16,9 @@
 #include <uapi/linux/mempolicy.h>
 #include <asm/page.h>
 
-struct notifier_block;
-
 struct bio;
+struct notifier_block;
+struct swap_info_struct;
 
 #define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
 #define SWAP_FLAG_PRIO_MASK	0x7fff
@@ -178,29 +178,6 @@ struct sysinfo;
 struct writeback_control;
 struct zone;
 
-/*
- * Max bad pages in the new format..
- */
-#define MAX_SWAP_BADPAGES \
-	((offsetof(union swap_header, magic.magic) - \
-	  offsetof(union swap_header, info.badpages)) / sizeof(int))
-
-enum {
-	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
-	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
-	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
-	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
-	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
-	SWP_BLKDEV	= (1 << 6),	/* its a block device */
-	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
-	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
-	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
-	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
-	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
-	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
-					/* add others here before... */
-};
-
 #define SWAP_CLUSTER_MAX 32UL
 #define SWAP_CLUSTER_MAX_SKIPPED (SWAP_CLUSTER_MAX << 10)
 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
@@ -219,56 +196,6 @@ enum {
 #define SWAP_NR_ORDERS		1
 #endif
 
-/*
- * We keep using same cluster for rotational device so IO will be sequential.
- * The purpose is to optimize SWAP throughput on these device.
- */
-struct swap_sequential_cluster {
-	unsigned int next[SWAP_NR_ORDERS]; /* Likely next allocation offset */
-};
-
-/*
- * The in-memory structure used to track swap areas.
- */
-struct swap_info_struct {
-	struct percpu_ref users;	/* indicate and keep swap device valid. */
-	unsigned long	flags;		/* SWP_USED etc: see above */
-	signed short	prio;		/* swap priority of this type */
-	struct plist_node list;		/* entry in swap_active_head */
-	signed char	type;		/* strange name for an index */
-	unsigned int	max;		/* size of this swap device */
-	unsigned long *zeromap;		/* kvmalloc'ed bitmap to track zero pages */
-	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
-	struct list_head free_clusters; /* free clusters list */
-	struct list_head full_clusters; /* full clusters list */
-	struct list_head nonfull_clusters[SWAP_NR_ORDERS];
-					/* list of cluster that contains at least one free slot */
-	struct list_head frag_clusters[SWAP_NR_ORDERS];
-					/* list of cluster that are fragmented or contented */
-	unsigned int pages;		/* total of usable pages of swap */
-	atomic_long_t inuse_pages;	/* number of those currently in use */
-	struct swap_sequential_cluster *global_cluster; /* Use one global cluster for rotating device */
-	spinlock_t global_cluster_lock;	/* Serialize usage of global cluster */
-	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
-	struct block_device *bdev;	/* swap device or bdev of swap file */
-	struct file *swap_file;		/* seldom referenced */
-	struct completion comp;		/* seldom referenced */
-	spinlock_t lock;		/*
-					 * protect map scan related fields like
-					 * inuse_pages and all cluster lists.
-					 * Other fields are only changed
-					 * at swapon/swapoff, so are protected
-					 * by swap_lock. changing flags need
-					 * hold this lock and swap_lock. If
-					 * both locks need hold, hold swap_lock
-					 * first.
-					 */
-	struct work_struct discard_work; /* discard worker */
-	struct work_struct reclaim_work; /* reclaim worker */
-	struct list_head discard_clusters; /* discard clusters list */
-	struct plist_node avail_list;   /* entry in swap_avail_head */
-};
-
 static inline swp_entry_t page_swap_entry(struct page *page)
 {
 	struct folio *folio = page_folio(page);
@@ -423,10 +350,7 @@ int find_first_swap(dev_t *device);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t swapdev_block(int, pgoff_t);
 extern int __swap_count(swp_entry_t entry);
-extern bool swap_entry_swapped(struct swap_info_struct *si, swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
-struct backing_dev_info;
-extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
 sector_t swap_folio_sector(struct folio *folio);
 
 /*
@@ -452,20 +376,7 @@ bool folio_free_swap(struct folio *folio);
 swp_entry_t swap_alloc_hibernation_slot(int type);
 void swap_free_hibernation_slot(swp_entry_t entry);
 
-static inline void put_swap_device(struct swap_info_struct *si)
-{
-	percpu_ref_put(&si->users);
-}
-
 #else /* CONFIG_SWAP */
-static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
-{
-	return NULL;
-}
-
-static inline void put_swap_device(struct swap_info_struct *si)
-{
-}
 
 #define get_nr_swap_pages()			0L
 #define total_swap_pages			0L
@@ -497,11 +408,6 @@ static inline int __swap_count(swp_entry_t entry)
 	return 0;
 }
 
-static inline bool swap_entry_swapped(struct swap_info_struct *si, swp_entry_t entry)
-{
-	return false;
-}
-
 static inline int swp_swapcount(swp_entry_t entry)
 {
 	return 0;
diff --git a/mm/swap.h b/mm/swap.h
index a77016f2423b..70974495bf15 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -8,6 +8,79 @@ struct swap_iocb;
 
 extern int page_cluster;
 
+/*
+ * We keep using same cluster for rotational device so IO will be sequential.
+ * The purpose is to optimize SWAP throughput on these device.
+ */
+struct swap_sequential_cluster {
+	unsigned int next[SWAP_NR_ORDERS]; /* Likely next allocation offset */
+};
+
+/*
+ * The in-memory structure used to track swap areas.
+ */
+struct swap_info_struct {
+	struct percpu_ref users;	/* indicate and keep swap device valid. */
+	unsigned long	flags;		/* SWP_USED etc: see above */
+	signed short	prio;		/* swap priority of this type */
+	struct plist_node list;		/* entry in swap_active_head */
+	signed char	type;		/* strange name for an index */
+	unsigned int	max;		/* size of this swap device */
+	unsigned long *zeromap;		/* kvmalloc'ed bitmap to track zero pages */
+	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
+	struct list_head free_clusters; /* free clusters list */
+	struct list_head full_clusters; /* full clusters list */
+	struct list_head nonfull_clusters[SWAP_NR_ORDERS];
+					/* list of cluster that contains at least one free slot */
+	struct list_head frag_clusters[SWAP_NR_ORDERS];
+					/* list of cluster that are fragmented or contented */
+	unsigned int pages;		/* total of usable pages of swap */
+	atomic_long_t inuse_pages;	/* number of those currently in use */
+	struct swap_sequential_cluster *global_cluster; /* Use one global cluster for rotating device */
+	spinlock_t global_cluster_lock;	/* Serialize usage of global cluster */
+	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
+	struct block_device *bdev;	/* swap device or bdev of swap file */
+	struct file *swap_file;		/* seldom referenced */
+	struct completion comp;		/* seldom referenced */
+	spinlock_t lock;		/*
+					 * protect map scan related fields like
+					 * inuse_pages and all cluster lists.
+					 * Other fields are only changed
+					 * at swapon/swapoff, so are protected
+					 * by swap_lock. changing flags need
+					 * hold this lock and swap_lock. If
+					 * both locks need hold, hold swap_lock
+					 * first.
+					 */
+	struct work_struct discard_work; /* discard worker */
+	struct work_struct reclaim_work; /* reclaim worker */
+	struct list_head discard_clusters; /* discard clusters list */
+	struct plist_node avail_list;   /* entry in swap_avail_head */
+};
+
+/*
+ * Max bad pages in the new format..
+ */
+#define MAX_SWAP_BADPAGES \
+	((offsetof(union swap_header, magic.magic) - \
+	  offsetof(union swap_header, info.badpages)) / sizeof(int))
+
+enum {
+	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
+	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
+	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
+	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
+	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
+	SWP_BLKDEV	= (1 << 6),	/* its a block device */
+	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
+	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
+	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
+	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
+	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
+	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
+					/* add others here before... */
+};
+
 #ifdef CONFIG_THP_SWAP
 #define SWAPFILE_CLUSTER	HPAGE_PMD_NR
 #define swap_entry_order(order)	(order)
@@ -352,6 +425,13 @@ static inline int non_swapcache_batch(swp_entry_t entry, int max_nr)
 	return i;
 }
 
+bool swap_entry_swapped(struct swap_info_struct *si, swp_entry_t entry);
+struct swap_info_struct *get_swap_device(swp_entry_t entry);
+static inline void put_swap_device(struct swap_info_struct *si)
+{
+	percpu_ref_put(&si->users);
+}
+
 #else /* CONFIG_SWAP */
 struct swap_iocb;
 static inline struct swap_cluster_info *swap_cluster_lock(
@@ -498,5 +578,17 @@ static inline int non_swapcache_batch(swp_entry_t entry, int max_nr)
 {
 	return 0;
 }
+static inline bool swap_entry_swapped(struct swap_info_struct *si,
+		swp_entry_t entry)
+{
+	return false;
+}
+static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
+{
+	return NULL;
+}
+static inline void put_swap_device(struct swap_info_struct *si)
+{
+}
 #endif /* CONFIG_SWAP */
 #endif /* _MM_SWAP_H */
-- 
2.53.0