diff options
Diffstat (limited to 'mm/swap.h')
| -rw-r--r-- | mm/swap.h | 448 |
1 files changed, 448 insertions, 0 deletions
diff --git a/mm/swap.h b/mm/swap.h new file mode 100644 index 000000000000..d034c13d8dd2 --- /dev/null +++ b/mm/swap.h @@ -0,0 +1,448 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _MM_SWAP_H +#define _MM_SWAP_H + +#include <linux/atomic.h> /* for atomic_long_t */ +struct mempolicy; +struct swap_iocb; + +extern int page_cluster; + +#ifdef CONFIG_THP_SWAP +#define SWAPFILE_CLUSTER HPAGE_PMD_NR +#define swap_entry_order(order) (order) +#else +#define SWAPFILE_CLUSTER 256 +#define swap_entry_order(order) 0 +#endif + +extern struct swap_info_struct *swap_info[]; + +/* + * We use this to track usage of a cluster. A cluster is a block of swap disk + * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All + * free clusters are organized into a list. We fetch an entry from the list to + * get a free cluster. + * + * The flags field determines if a cluster is free. This is + * protected by cluster lock. + */ +struct swap_cluster_info { + spinlock_t lock; /* + * Protect swap_cluster_info fields + * other than list, and swap_info_struct->swap_map + * elements corresponding to the swap cluster. + */ + u16 count; + u8 flags; + u8 order; + atomic_long_t __rcu *table; /* Swap table entries, see mm/swap_table.h */ + struct list_head list; +}; + +/* All on-list cluster must have a non-zero flag. */ +enum swap_cluster_flags { + CLUSTER_FLAG_NONE = 0, /* For temporary off-list cluster */ + CLUSTER_FLAG_FREE, + CLUSTER_FLAG_NONFULL, + CLUSTER_FLAG_FRAG, + /* Clusters with flags above are allocatable */ + CLUSTER_FLAG_USABLE = CLUSTER_FLAG_FRAG, + CLUSTER_FLAG_FULL, + CLUSTER_FLAG_DISCARD, + CLUSTER_FLAG_MAX, +}; + +#ifdef CONFIG_SWAP +#include <linux/swapops.h> /* for swp_offset */ +#include <linux/blk_types.h> /* for bio_end_io_t */ + +static inline unsigned int swp_cluster_offset(swp_entry_t entry) +{ + return swp_offset(entry) % SWAPFILE_CLUSTER; +} + +/* + * Callers of all helpers below must ensure the entry, type, or offset is + * valid, and protect the swap device with reference count or locks. + */ +static inline struct swap_info_struct *__swap_type_to_info(int type) +{ + struct swap_info_struct *si; + + si = READ_ONCE(swap_info[type]); /* rcu_dereference() */ + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ + return si; +} + +static inline struct swap_info_struct *__swap_entry_to_info(swp_entry_t entry) +{ + return __swap_type_to_info(swp_type(entry)); +} + +static inline struct swap_cluster_info *__swap_offset_to_cluster( + struct swap_info_struct *si, pgoff_t offset) +{ + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ + VM_WARN_ON_ONCE(offset >= si->max); + return &si->cluster_info[offset / SWAPFILE_CLUSTER]; +} + +static inline struct swap_cluster_info *__swap_entry_to_cluster(swp_entry_t entry) +{ + return __swap_offset_to_cluster(__swap_entry_to_info(entry), + swp_offset(entry)); +} + +static __always_inline struct swap_cluster_info *__swap_cluster_lock( + struct swap_info_struct *si, unsigned long offset, bool irq) +{ + struct swap_cluster_info *ci = __swap_offset_to_cluster(si, offset); + + /* + * Nothing modifies swap cache in an IRQ context. All access to + * swap cache is wrapped by swap_cache_* helpers, and swap cache + * writeback is handled outside of IRQs. Swapin or swapout never + * occurs in IRQ, and neither does in-place split or replace. + * + * Besides, modifying swap cache requires synchronization with + * swap_map, which was never IRQ safe. + */ + VM_WARN_ON_ONCE(!in_task()); + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ + if (irq) + spin_lock_irq(&ci->lock); + else + spin_lock(&ci->lock); + return ci; +} + +/** + * swap_cluster_lock - Lock and return the swap cluster of given offset. + * @si: swap device the cluster belongs to. + * @offset: the swap entry offset, pointing to a valid slot. + * + * Context: The caller must ensure the offset is in the valid range and + * protect the swap device with reference count or locks. + */ +static inline struct swap_cluster_info *swap_cluster_lock( + struct swap_info_struct *si, unsigned long offset) +{ + return __swap_cluster_lock(si, offset, false); +} + +static inline struct swap_cluster_info *__swap_cluster_get_and_lock( + const struct folio *folio, bool irq) +{ + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio); + return __swap_cluster_lock(__swap_entry_to_info(folio->swap), + swp_offset(folio->swap), irq); +} + +/* + * swap_cluster_get_and_lock - Locks the cluster that holds a folio's entries. + * @folio: The folio. + * + * This locks and returns the swap cluster that contains a folio's swap + * entries. The swap entries of a folio are always in one single cluster. + * The folio has to be locked so its swap entries won't change and the + * cluster won't be freed. + * + * Context: Caller must ensure the folio is locked and in the swap cache. + * Return: Pointer to the swap cluster. + */ +static inline struct swap_cluster_info *swap_cluster_get_and_lock( + const struct folio *folio) +{ + return __swap_cluster_get_and_lock(folio, false); +} + +/* + * swap_cluster_get_and_lock_irq - Locks the cluster that holds a folio's entries. + * @folio: The folio. + * + * Same as swap_cluster_get_and_lock but also disable IRQ. + * + * Context: Caller must ensure the folio is locked and in the swap cache. + * Return: Pointer to the swap cluster. + */ +static inline struct swap_cluster_info *swap_cluster_get_and_lock_irq( + const struct folio *folio) +{ + return __swap_cluster_get_and_lock(folio, true); +} + +static inline void swap_cluster_unlock(struct swap_cluster_info *ci) +{ + spin_unlock(&ci->lock); +} + +static inline void swap_cluster_unlock_irq(struct swap_cluster_info *ci) +{ + spin_unlock_irq(&ci->lock); +} + +/* linux/mm/page_io.c */ +int sio_pool_init(void); +struct swap_iocb; +void swap_read_folio(struct folio *folio, struct swap_iocb **plug); +void __swap_read_unplug(struct swap_iocb *plug); +static inline void swap_read_unplug(struct swap_iocb *plug) +{ + if (unlikely(plug)) + __swap_read_unplug(plug); +} +void swap_write_unplug(struct swap_iocb *sio); +int swap_writeout(struct folio *folio, struct swap_iocb **swap_plug); +void __swap_writepage(struct folio *folio, struct swap_iocb **swap_plug); + +/* linux/mm/swap_state.c */ +extern struct address_space swap_space __ro_after_init; +static inline struct address_space *swap_address_space(swp_entry_t entry) +{ + return &swap_space; +} + +/* + * Return the swap device position of the swap entry. + */ +static inline loff_t swap_dev_pos(swp_entry_t entry) +{ + return ((loff_t)swp_offset(entry)) << PAGE_SHIFT; +} + +/** + * folio_matches_swap_entry - Check if a folio matches a given swap entry. + * @folio: The folio. + * @entry: The swap entry to check against. + * + * Context: The caller should have the folio locked to ensure it's stable + * and nothing will move it in or out of the swap cache. + * Return: true or false. + */ +static inline bool folio_matches_swap_entry(const struct folio *folio, + swp_entry_t entry) +{ + swp_entry_t folio_entry = folio->swap; + long nr_pages = folio_nr_pages(folio); + + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + if (!folio_test_swapcache(folio)) + return false; + VM_WARN_ON_ONCE_FOLIO(!IS_ALIGNED(folio_entry.val, nr_pages), folio); + return folio_entry.val == round_down(entry.val, nr_pages); +} + +/* + * All swap cache helpers below require the caller to ensure the swap entries + * used are valid and stablize the device by any of the following ways: + * - Hold a reference by get_swap_device(): this ensures a single entry is + * valid and increases the swap device's refcount. + * - Locking a folio in the swap cache: this ensures the folio's swap entries + * are valid and pinned, also implies reference to the device. + * - Locking anything referencing the swap entry: e.g. PTL that protects + * swap entries in the page table, similar to locking swap cache folio. + * - See the comment of get_swap_device() for more complex usage. + */ +struct folio *swap_cache_get_folio(swp_entry_t entry); +void *swap_cache_get_shadow(swp_entry_t entry); +void swap_cache_add_folio(struct folio *folio, swp_entry_t entry, void **shadow); +void swap_cache_del_folio(struct folio *folio); +/* Below helpers require the caller to lock and pass in the swap cluster. */ +void __swap_cache_del_folio(struct swap_cluster_info *ci, + struct folio *folio, swp_entry_t entry, void *shadow); +void __swap_cache_replace_folio(struct swap_cluster_info *ci, + struct folio *old, struct folio *new); +void __swap_cache_clear_shadow(swp_entry_t entry, int nr_ents); + +void show_swap_cache_info(void); +void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr); +struct folio *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, + struct vm_area_struct *vma, unsigned long addr, + struct swap_iocb **plug); +struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_flags, + struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated, + bool skip_if_exists); +struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag, + struct mempolicy *mpol, pgoff_t ilx); +struct folio *swapin_readahead(swp_entry_t entry, gfp_t flag, + struct vm_fault *vmf); +void swap_update_readahead(struct folio *folio, struct vm_area_struct *vma, + unsigned long addr); + +static inline unsigned int folio_swap_flags(struct folio *folio) +{ + return __swap_entry_to_info(folio->swap)->flags; +} + +/* + * Return the count of contiguous swap entries that share the same + * zeromap status as the starting entry. If is_zeromap is not NULL, + * it will return the zeromap status of the starting entry. + */ +static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr, + bool *is_zeromap) +{ + struct swap_info_struct *sis = __swap_entry_to_info(entry); + unsigned long start = swp_offset(entry); + unsigned long end = start + max_nr; + bool first_bit; + + first_bit = test_bit(start, sis->zeromap); + if (is_zeromap) + *is_zeromap = first_bit; + + if (max_nr <= 1) + return max_nr; + if (first_bit) + return find_next_zero_bit(sis->zeromap, end, start) - start; + else + return find_next_bit(sis->zeromap, end, start) - start; +} + +static inline int non_swapcache_batch(swp_entry_t entry, int max_nr) +{ + struct swap_info_struct *si = __swap_entry_to_info(entry); + pgoff_t offset = swp_offset(entry); + int i; + + /* + * While allocating a large folio and doing mTHP swapin, we need to + * ensure all entries are not cached, otherwise, the mTHP folio will + * be in conflict with the folio in swap cache. + */ + for (i = 0; i < max_nr; i++) { + if ((si->swap_map[offset + i] & SWAP_HAS_CACHE)) + return i; + } + + return i; +} + +#else /* CONFIG_SWAP */ +struct swap_iocb; +static inline struct swap_cluster_info *swap_cluster_lock( + struct swap_info_struct *si, pgoff_t offset, bool irq) +{ + return NULL; +} + +static inline struct swap_cluster_info *swap_cluster_get_and_lock( + struct folio *folio) +{ + return NULL; +} + +static inline struct swap_cluster_info *swap_cluster_get_and_lock_irq( + struct folio *folio) +{ + return NULL; +} + +static inline void swap_cluster_unlock(struct swap_cluster_info *ci) +{ +} + +static inline void swap_cluster_unlock_irq(struct swap_cluster_info *ci) +{ +} + +static inline struct swap_info_struct *__swap_entry_to_info(swp_entry_t entry) +{ + return NULL; +} + +static inline void swap_read_folio(struct folio *folio, struct swap_iocb **plug) +{ +} +static inline void swap_write_unplug(struct swap_iocb *sio) +{ +} + +static inline struct address_space *swap_address_space(swp_entry_t entry) +{ + return NULL; +} + +static inline bool folio_matches_swap_entry(const struct folio *folio, swp_entry_t entry) +{ + return false; +} + +static inline void show_swap_cache_info(void) +{ +} + +static inline struct folio *swap_cluster_readahead(swp_entry_t entry, + gfp_t gfp_mask, struct mempolicy *mpol, pgoff_t ilx) +{ + return NULL; +} + +static inline struct folio *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, + struct vm_fault *vmf) +{ + return NULL; +} + +static inline void swap_update_readahead(struct folio *folio, + struct vm_area_struct *vma, unsigned long addr) +{ +} + +static inline int swap_writeout(struct folio *folio, + struct swap_iocb **swap_plug) +{ + return 0; +} + +static inline void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr) +{ +} + +static inline struct folio *swap_cache_get_folio(swp_entry_t entry) +{ + return NULL; +} + +static inline void *swap_cache_get_shadow(swp_entry_t entry) +{ + return NULL; +} + +static inline void swap_cache_add_folio(struct folio *folio, swp_entry_t entry, void **shadow) +{ +} + +static inline void swap_cache_del_folio(struct folio *folio) +{ +} + +static inline void __swap_cache_del_folio(struct swap_cluster_info *ci, + struct folio *folio, swp_entry_t entry, void *shadow) +{ +} + +static inline void __swap_cache_replace_folio(struct swap_cluster_info *ci, + struct folio *old, struct folio *new) +{ +} + +static inline unsigned int folio_swap_flags(struct folio *folio) +{ + return 0; +} + +static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr, + bool *has_zeromap) +{ + return 0; +} + +static inline int non_swapcache_batch(swp_entry_t entry, int max_nr) +{ + return 0; +} +#endif /* CONFIG_SWAP */ +#endif /* _MM_SWAP_H */ |