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3828 lines
96 KiB
3828 lines
96 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/mm/swapfile.c |
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* |
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
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* Swap reorganised 29.12.95, Stephen Tweedie |
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*/ |
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|
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#include <linux/mm.h> |
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#include <linux/sched/mm.h> |
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#include <linux/sched/task.h> |
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#include <linux/hugetlb.h> |
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#include <linux/mman.h> |
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#include <linux/slab.h> |
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#include <linux/kernel_stat.h> |
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#include <linux/swap.h> |
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#include <linux/vmalloc.h> |
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#include <linux/pagemap.h> |
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#include <linux/namei.h> |
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#include <linux/shmem_fs.h> |
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#include <linux/blkdev.h> |
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#include <linux/random.h> |
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#include <linux/writeback.h> |
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#include <linux/proc_fs.h> |
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#include <linux/seq_file.h> |
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#include <linux/init.h> |
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#include <linux/ksm.h> |
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#include <linux/rmap.h> |
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#include <linux/security.h> |
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#include <linux/backing-dev.h> |
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#include <linux/mutex.h> |
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#include <linux/capability.h> |
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#include <linux/syscalls.h> |
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#include <linux/memcontrol.h> |
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#include <linux/poll.h> |
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#include <linux/oom.h> |
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#include <linux/frontswap.h> |
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#include <linux/swapfile.h> |
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#include <linux/export.h> |
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#include <linux/swap_slots.h> |
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#include <linux/sort.h> |
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#include <linux/completion.h> |
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|
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#include <asm/tlbflush.h> |
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#include <linux/swapops.h> |
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#include <linux/swap_cgroup.h> |
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|
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static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
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unsigned char); |
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static void free_swap_count_continuations(struct swap_info_struct *); |
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|
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DEFINE_SPINLOCK(swap_lock); |
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static unsigned int nr_swapfiles; |
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atomic_long_t nr_swap_pages; |
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/* |
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* Some modules use swappable objects and may try to swap them out under |
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* memory pressure (via the shrinker). Before doing so, they may wish to |
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* check to see if any swap space is available. |
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*/ |
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EXPORT_SYMBOL_GPL(nr_swap_pages); |
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/* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
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long total_swap_pages; |
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static int least_priority = -1; |
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|
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static const char Bad_file[] = "Bad swap file entry "; |
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static const char Unused_file[] = "Unused swap file entry "; |
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static const char Bad_offset[] = "Bad swap offset entry "; |
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static const char Unused_offset[] = "Unused swap offset entry "; |
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|
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/* |
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* all active swap_info_structs |
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* protected with swap_lock, and ordered by priority. |
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*/ |
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PLIST_HEAD(swap_active_head); |
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|
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/* |
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* all available (active, not full) swap_info_structs |
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* protected with swap_avail_lock, ordered by priority. |
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* This is used by get_swap_page() instead of swap_active_head |
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* because swap_active_head includes all swap_info_structs, |
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* but get_swap_page() doesn't need to look at full ones. |
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* This uses its own lock instead of swap_lock because when a |
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* swap_info_struct changes between not-full/full, it needs to |
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* add/remove itself to/from this list, but the swap_info_struct->lock |
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* is held and the locking order requires swap_lock to be taken |
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* before any swap_info_struct->lock. |
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*/ |
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static struct plist_head *swap_avail_heads; |
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static DEFINE_SPINLOCK(swap_avail_lock); |
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|
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struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
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|
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static DEFINE_MUTEX(swapon_mutex); |
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|
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static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
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/* Activity counter to indicate that a swapon or swapoff has occurred */ |
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static atomic_t proc_poll_event = ATOMIC_INIT(0); |
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|
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atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
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static struct swap_info_struct *swap_type_to_swap_info(int type) |
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{ |
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if (type >= MAX_SWAPFILES) |
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return NULL; |
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|
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return READ_ONCE(swap_info[type]); /* rcu_dereference() */ |
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} |
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|
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static inline unsigned char swap_count(unsigned char ent) |
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{ |
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return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ |
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} |
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|
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/* Reclaim the swap entry anyway if possible */ |
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#define TTRS_ANYWAY 0x1 |
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/* |
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* Reclaim the swap entry if there are no more mappings of the |
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* corresponding page |
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*/ |
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#define TTRS_UNMAPPED 0x2 |
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/* Reclaim the swap entry if swap is getting full*/ |
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#define TTRS_FULL 0x4 |
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|
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/* returns 1 if swap entry is freed */ |
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static int __try_to_reclaim_swap(struct swap_info_struct *si, |
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unsigned long offset, unsigned long flags) |
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{ |
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swp_entry_t entry = swp_entry(si->type, offset); |
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struct page *page; |
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int ret = 0; |
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page = find_get_page(swap_address_space(entry), offset); |
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if (!page) |
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return 0; |
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/* |
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* When this function is called from scan_swap_map_slots() and it's |
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* called by vmscan.c at reclaiming pages. So, we hold a lock on a page, |
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* here. We have to use trylock for avoiding deadlock. This is a special |
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* case and you should use try_to_free_swap() with explicit lock_page() |
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* in usual operations. |
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*/ |
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if (trylock_page(page)) { |
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if ((flags & TTRS_ANYWAY) || |
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((flags & TTRS_UNMAPPED) && !page_mapped(page)) || |
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((flags & TTRS_FULL) && mem_cgroup_swap_full(page))) |
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ret = try_to_free_swap(page); |
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unlock_page(page); |
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} |
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put_page(page); |
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return ret; |
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} |
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static inline struct swap_extent *first_se(struct swap_info_struct *sis) |
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{ |
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struct rb_node *rb = rb_first(&sis->swap_extent_root); |
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return rb_entry(rb, struct swap_extent, rb_node); |
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} |
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|
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static inline struct swap_extent *next_se(struct swap_extent *se) |
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{ |
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struct rb_node *rb = rb_next(&se->rb_node); |
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return rb ? rb_entry(rb, struct swap_extent, rb_node) : NULL; |
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} |
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|
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/* |
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* swapon tell device that all the old swap contents can be discarded, |
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* to allow the swap device to optimize its wear-levelling. |
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*/ |
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static int discard_swap(struct swap_info_struct *si) |
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{ |
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struct swap_extent *se; |
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sector_t start_block; |
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sector_t nr_blocks; |
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int err = 0; |
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|
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/* Do not discard the swap header page! */ |
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se = first_se(si); |
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start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
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nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
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if (nr_blocks) { |
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err = blkdev_issue_discard(si->bdev, start_block, |
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nr_blocks, GFP_KERNEL, 0); |
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if (err) |
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return err; |
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cond_resched(); |
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} |
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for (se = next_se(se); se; se = next_se(se)) { |
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start_block = se->start_block << (PAGE_SHIFT - 9); |
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nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
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err = blkdev_issue_discard(si->bdev, start_block, |
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nr_blocks, GFP_KERNEL, 0); |
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if (err) |
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break; |
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|
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cond_resched(); |
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} |
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return err; /* That will often be -EOPNOTSUPP */ |
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} |
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static struct swap_extent * |
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offset_to_swap_extent(struct swap_info_struct *sis, unsigned long offset) |
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{ |
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struct swap_extent *se; |
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struct rb_node *rb; |
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rb = sis->swap_extent_root.rb_node; |
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while (rb) { |
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se = rb_entry(rb, struct swap_extent, rb_node); |
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if (offset < se->start_page) |
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rb = rb->rb_left; |
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else if (offset >= se->start_page + se->nr_pages) |
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rb = rb->rb_right; |
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else |
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return se; |
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} |
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/* It *must* be present */ |
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BUG(); |
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} |
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sector_t swap_page_sector(struct page *page) |
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{ |
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struct swap_info_struct *sis = page_swap_info(page); |
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struct swap_extent *se; |
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sector_t sector; |
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pgoff_t offset; |
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offset = __page_file_index(page); |
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se = offset_to_swap_extent(sis, offset); |
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sector = se->start_block + (offset - se->start_page); |
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return sector << (PAGE_SHIFT - 9); |
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} |
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|
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/* |
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* swap allocation tell device that a cluster of swap can now be discarded, |
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* to allow the swap device to optimize its wear-levelling. |
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*/ |
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static void discard_swap_cluster(struct swap_info_struct *si, |
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pgoff_t start_page, pgoff_t nr_pages) |
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{ |
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struct swap_extent *se = offset_to_swap_extent(si, start_page); |
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|
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while (nr_pages) { |
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pgoff_t offset = start_page - se->start_page; |
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sector_t start_block = se->start_block + offset; |
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sector_t nr_blocks = se->nr_pages - offset; |
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if (nr_blocks > nr_pages) |
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nr_blocks = nr_pages; |
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start_page += nr_blocks; |
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nr_pages -= nr_blocks; |
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start_block <<= PAGE_SHIFT - 9; |
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nr_blocks <<= PAGE_SHIFT - 9; |
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if (blkdev_issue_discard(si->bdev, start_block, |
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nr_blocks, GFP_NOIO, 0)) |
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break; |
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|
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se = next_se(se); |
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} |
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} |
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|
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#ifdef CONFIG_THP_SWAP |
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#define SWAPFILE_CLUSTER HPAGE_PMD_NR |
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|
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#define swap_entry_size(size) (size) |
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#else |
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#define SWAPFILE_CLUSTER 256 |
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|
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/* |
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* Define swap_entry_size() as constant to let compiler to optimize |
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* out some code if !CONFIG_THP_SWAP |
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*/ |
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#define swap_entry_size(size) 1 |
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#endif |
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#define LATENCY_LIMIT 256 |
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|
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static inline void cluster_set_flag(struct swap_cluster_info *info, |
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unsigned int flag) |
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{ |
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info->flags = flag; |
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} |
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static inline unsigned int cluster_count(struct swap_cluster_info *info) |
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{ |
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return info->data; |
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} |
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static inline void cluster_set_count(struct swap_cluster_info *info, |
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unsigned int c) |
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{ |
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info->data = c; |
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} |
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static inline void cluster_set_count_flag(struct swap_cluster_info *info, |
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unsigned int c, unsigned int f) |
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{ |
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info->flags = f; |
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info->data = c; |
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} |
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static inline unsigned int cluster_next(struct swap_cluster_info *info) |
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{ |
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return info->data; |
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} |
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static inline void cluster_set_next(struct swap_cluster_info *info, |
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unsigned int n) |
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{ |
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info->data = n; |
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} |
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static inline void cluster_set_next_flag(struct swap_cluster_info *info, |
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unsigned int n, unsigned int f) |
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{ |
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info->flags = f; |
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info->data = n; |
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} |
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static inline bool cluster_is_free(struct swap_cluster_info *info) |
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{ |
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return info->flags & CLUSTER_FLAG_FREE; |
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} |
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static inline bool cluster_is_null(struct swap_cluster_info *info) |
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{ |
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return info->flags & CLUSTER_FLAG_NEXT_NULL; |
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} |
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static inline void cluster_set_null(struct swap_cluster_info *info) |
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{ |
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info->flags = CLUSTER_FLAG_NEXT_NULL; |
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info->data = 0; |
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} |
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static inline bool cluster_is_huge(struct swap_cluster_info *info) |
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{ |
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if (IS_ENABLED(CONFIG_THP_SWAP)) |
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return info->flags & CLUSTER_FLAG_HUGE; |
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return false; |
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} |
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static inline void cluster_clear_huge(struct swap_cluster_info *info) |
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{ |
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info->flags &= ~CLUSTER_FLAG_HUGE; |
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} |
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static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
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unsigned long offset) |
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{ |
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struct swap_cluster_info *ci; |
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ci = si->cluster_info; |
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if (ci) { |
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ci += offset / SWAPFILE_CLUSTER; |
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spin_lock(&ci->lock); |
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} |
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return ci; |
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} |
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|
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static inline void unlock_cluster(struct swap_cluster_info *ci) |
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{ |
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if (ci) |
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spin_unlock(&ci->lock); |
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} |
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|
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/* |
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* Determine the locking method in use for this device. Return |
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* swap_cluster_info if SSD-style cluster-based locking is in place. |
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*/ |
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static inline struct swap_cluster_info *lock_cluster_or_swap_info( |
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struct swap_info_struct *si, unsigned long offset) |
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{ |
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struct swap_cluster_info *ci; |
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|
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/* Try to use fine-grained SSD-style locking if available: */ |
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ci = lock_cluster(si, offset); |
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/* Otherwise, fall back to traditional, coarse locking: */ |
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if (!ci) |
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spin_lock(&si->lock); |
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return ci; |
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} |
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static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
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struct swap_cluster_info *ci) |
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{ |
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if (ci) |
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unlock_cluster(ci); |
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else |
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spin_unlock(&si->lock); |
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} |
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static inline bool cluster_list_empty(struct swap_cluster_list *list) |
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{ |
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return cluster_is_null(&list->head); |
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} |
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static inline unsigned int cluster_list_first(struct swap_cluster_list *list) |
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{ |
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return cluster_next(&list->head); |
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} |
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|
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static void cluster_list_init(struct swap_cluster_list *list) |
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{ |
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cluster_set_null(&list->head); |
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cluster_set_null(&list->tail); |
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} |
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|
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static void cluster_list_add_tail(struct swap_cluster_list *list, |
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struct swap_cluster_info *ci, |
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unsigned int idx) |
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{ |
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if (cluster_list_empty(list)) { |
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cluster_set_next_flag(&list->head, idx, 0); |
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cluster_set_next_flag(&list->tail, idx, 0); |
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} else { |
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struct swap_cluster_info *ci_tail; |
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unsigned int tail = cluster_next(&list->tail); |
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|
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/* |
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* Nested cluster lock, but both cluster locks are |
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* only acquired when we held swap_info_struct->lock |
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*/ |
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ci_tail = ci + tail; |
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spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); |
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cluster_set_next(ci_tail, idx); |
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spin_unlock(&ci_tail->lock); |
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cluster_set_next_flag(&list->tail, idx, 0); |
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} |
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} |
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|
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static unsigned int cluster_list_del_first(struct swap_cluster_list *list, |
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struct swap_cluster_info *ci) |
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{ |
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unsigned int idx; |
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|
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idx = cluster_next(&list->head); |
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if (cluster_next(&list->tail) == idx) { |
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cluster_set_null(&list->head); |
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cluster_set_null(&list->tail); |
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} else |
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cluster_set_next_flag(&list->head, |
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cluster_next(&ci[idx]), 0); |
|
|
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return idx; |
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} |
|
|
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/* Add a cluster to discard list and schedule it to do discard */ |
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static void swap_cluster_schedule_discard(struct swap_info_struct *si, |
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unsigned int idx) |
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{ |
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/* |
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* If scan_swap_map_slots() can't find a free cluster, it will check |
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* si->swap_map directly. To make sure the discarding cluster isn't |
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* taken by scan_swap_map_slots(), mark the swap entries bad (occupied). |
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* It will be cleared after discard |
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*/ |
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memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
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SWAP_MAP_BAD, SWAPFILE_CLUSTER); |
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|
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cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); |
|
|
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schedule_work(&si->discard_work); |
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} |
|
|
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static void __free_cluster(struct swap_info_struct *si, unsigned long idx) |
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{ |
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struct swap_cluster_info *ci = si->cluster_info; |
|
|
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cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); |
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cluster_list_add_tail(&si->free_clusters, ci, idx); |
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} |
|
|
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/* |
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* Doing discard actually. After a cluster discard is finished, the cluster |
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* will be added to free cluster list. caller should hold si->lock. |
|
*/ |
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static void swap_do_scheduled_discard(struct swap_info_struct *si) |
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{ |
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struct swap_cluster_info *info, *ci; |
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unsigned int idx; |
|
|
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info = si->cluster_info; |
|
|
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while (!cluster_list_empty(&si->discard_clusters)) { |
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idx = cluster_list_del_first(&si->discard_clusters, info); |
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spin_unlock(&si->lock); |
|
|
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discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, |
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SWAPFILE_CLUSTER); |
|
|
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spin_lock(&si->lock); |
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ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); |
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__free_cluster(si, idx); |
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memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
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0, SWAPFILE_CLUSTER); |
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unlock_cluster(ci); |
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} |
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} |
|
|
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static void swap_discard_work(struct work_struct *work) |
|
{ |
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struct swap_info_struct *si; |
|
|
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si = container_of(work, struct swap_info_struct, discard_work); |
|
|
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spin_lock(&si->lock); |
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swap_do_scheduled_discard(si); |
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spin_unlock(&si->lock); |
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} |
|
|
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static void swap_users_ref_free(struct percpu_ref *ref) |
|
{ |
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struct swap_info_struct *si; |
|
|
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si = container_of(ref, struct swap_info_struct, users); |
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complete(&si->comp); |
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} |
|
|
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static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) |
|
{ |
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struct swap_cluster_info *ci = si->cluster_info; |
|
|
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VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); |
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cluster_list_del_first(&si->free_clusters, ci); |
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cluster_set_count_flag(ci + idx, 0, 0); |
|
} |
|
|
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static void free_cluster(struct swap_info_struct *si, unsigned long idx) |
|
{ |
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struct swap_cluster_info *ci = si->cluster_info + idx; |
|
|
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VM_BUG_ON(cluster_count(ci) != 0); |
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/* |
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* If the swap is discardable, prepare discard the cluster |
|
* instead of free it immediately. The cluster will be freed |
|
* after discard. |
|
*/ |
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if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
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(SWP_WRITEOK | SWP_PAGE_DISCARD)) { |
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swap_cluster_schedule_discard(si, idx); |
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return; |
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} |
|
|
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__free_cluster(si, idx); |
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} |
|
|
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/* |
|
* The cluster corresponding to page_nr will be used. The cluster will be |
|
* removed from free cluster list and its usage counter will be increased. |
|
*/ |
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static void inc_cluster_info_page(struct swap_info_struct *p, |
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struct swap_cluster_info *cluster_info, unsigned long page_nr) |
|
{ |
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unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
|
|
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if (!cluster_info) |
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return; |
|
if (cluster_is_free(&cluster_info[idx])) |
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alloc_cluster(p, idx); |
|
|
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VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); |
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cluster_set_count(&cluster_info[idx], |
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cluster_count(&cluster_info[idx]) + 1); |
|
} |
|
|
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/* |
|
* The cluster corresponding to page_nr decreases one usage. If the usage |
|
* counter becomes 0, which means no page in the cluster is in using, we can |
|
* optionally discard the cluster and add it to free cluster list. |
|
*/ |
|
static void dec_cluster_info_page(struct swap_info_struct *p, |
|
struct swap_cluster_info *cluster_info, unsigned long page_nr) |
|
{ |
|
unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
|
|
|
if (!cluster_info) |
|
return; |
|
|
|
VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); |
|
cluster_set_count(&cluster_info[idx], |
|
cluster_count(&cluster_info[idx]) - 1); |
|
|
|
if (cluster_count(&cluster_info[idx]) == 0) |
|
free_cluster(p, idx); |
|
} |
|
|
|
/* |
|
* It's possible scan_swap_map_slots() uses a free cluster in the middle of free |
|
* cluster list. Avoiding such abuse to avoid list corruption. |
|
*/ |
|
static bool |
|
scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, |
|
unsigned long offset) |
|
{ |
|
struct percpu_cluster *percpu_cluster; |
|
bool conflict; |
|
|
|
offset /= SWAPFILE_CLUSTER; |
|
conflict = !cluster_list_empty(&si->free_clusters) && |
|
offset != cluster_list_first(&si->free_clusters) && |
|
cluster_is_free(&si->cluster_info[offset]); |
|
|
|
if (!conflict) |
|
return false; |
|
|
|
percpu_cluster = this_cpu_ptr(si->percpu_cluster); |
|
cluster_set_null(&percpu_cluster->index); |
|
return true; |
|
} |
|
|
|
/* |
|
* Try to get a swap entry from current cpu's swap entry pool (a cluster). This |
|
* might involve allocating a new cluster for current CPU too. |
|
*/ |
|
static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, |
|
unsigned long *offset, unsigned long *scan_base) |
|
{ |
|
struct percpu_cluster *cluster; |
|
struct swap_cluster_info *ci; |
|
unsigned long tmp, max; |
|
|
|
new_cluster: |
|
cluster = this_cpu_ptr(si->percpu_cluster); |
|
if (cluster_is_null(&cluster->index)) { |
|
if (!cluster_list_empty(&si->free_clusters)) { |
|
cluster->index = si->free_clusters.head; |
|
cluster->next = cluster_next(&cluster->index) * |
|
SWAPFILE_CLUSTER; |
|
} else if (!cluster_list_empty(&si->discard_clusters)) { |
|
/* |
|
* we don't have free cluster but have some clusters in |
|
* discarding, do discard now and reclaim them, then |
|
* reread cluster_next_cpu since we dropped si->lock |
|
*/ |
|
swap_do_scheduled_discard(si); |
|
*scan_base = this_cpu_read(*si->cluster_next_cpu); |
|
*offset = *scan_base; |
|
goto new_cluster; |
|
} else |
|
return false; |
|
} |
|
|
|
/* |
|
* Other CPUs can use our cluster if they can't find a free cluster, |
|
* check if there is still free entry in the cluster |
|
*/ |
|
tmp = cluster->next; |
|
max = min_t(unsigned long, si->max, |
|
(cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); |
|
if (tmp < max) { |
|
ci = lock_cluster(si, tmp); |
|
while (tmp < max) { |
|
if (!si->swap_map[tmp]) |
|
break; |
|
tmp++; |
|
} |
|
unlock_cluster(ci); |
|
} |
|
if (tmp >= max) { |
|
cluster_set_null(&cluster->index); |
|
goto new_cluster; |
|
} |
|
cluster->next = tmp + 1; |
|
*offset = tmp; |
|
*scan_base = tmp; |
|
return true; |
|
} |
|
|
|
static void __del_from_avail_list(struct swap_info_struct *p) |
|
{ |
|
int nid; |
|
|
|
for_each_node(nid) |
|
plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); |
|
} |
|
|
|
static void del_from_avail_list(struct swap_info_struct *p) |
|
{ |
|
spin_lock(&swap_avail_lock); |
|
__del_from_avail_list(p); |
|
spin_unlock(&swap_avail_lock); |
|
} |
|
|
|
static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
|
unsigned int nr_entries) |
|
{ |
|
unsigned int end = offset + nr_entries - 1; |
|
|
|
if (offset == si->lowest_bit) |
|
si->lowest_bit += nr_entries; |
|
if (end == si->highest_bit) |
|
WRITE_ONCE(si->highest_bit, si->highest_bit - nr_entries); |
|
si->inuse_pages += nr_entries; |
|
if (si->inuse_pages == si->pages) { |
|
si->lowest_bit = si->max; |
|
si->highest_bit = 0; |
|
del_from_avail_list(si); |
|
} |
|
} |
|
|
|
static void add_to_avail_list(struct swap_info_struct *p) |
|
{ |
|
int nid; |
|
|
|
spin_lock(&swap_avail_lock); |
|
for_each_node(nid) { |
|
WARN_ON(!plist_node_empty(&p->avail_lists[nid])); |
|
plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); |
|
} |
|
spin_unlock(&swap_avail_lock); |
|
} |
|
|
|
static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
|
unsigned int nr_entries) |
|
{ |
|
unsigned long begin = offset; |
|
unsigned long end = offset + nr_entries - 1; |
|
void (*swap_slot_free_notify)(struct block_device *, unsigned long); |
|
|
|
if (offset < si->lowest_bit) |
|
si->lowest_bit = offset; |
|
if (end > si->highest_bit) { |
|
bool was_full = !si->highest_bit; |
|
|
|
WRITE_ONCE(si->highest_bit, end); |
|
if (was_full && (si->flags & SWP_WRITEOK)) |
|
add_to_avail_list(si); |
|
} |
|
atomic_long_add(nr_entries, &nr_swap_pages); |
|
si->inuse_pages -= nr_entries; |
|
if (si->flags & SWP_BLKDEV) |
|
swap_slot_free_notify = |
|
si->bdev->bd_disk->fops->swap_slot_free_notify; |
|
else |
|
swap_slot_free_notify = NULL; |
|
while (offset <= end) { |
|
arch_swap_invalidate_page(si->type, offset); |
|
frontswap_invalidate_page(si->type, offset); |
|
if (swap_slot_free_notify) |
|
swap_slot_free_notify(si->bdev, offset); |
|
offset++; |
|
} |
|
clear_shadow_from_swap_cache(si->type, begin, end); |
|
} |
|
|
|
static void set_cluster_next(struct swap_info_struct *si, unsigned long next) |
|
{ |
|
unsigned long prev; |
|
|
|
if (!(si->flags & SWP_SOLIDSTATE)) { |
|
si->cluster_next = next; |
|
return; |
|
} |
|
|
|
prev = this_cpu_read(*si->cluster_next_cpu); |
|
/* |
|
* Cross the swap address space size aligned trunk, choose |
|
* another trunk randomly to avoid lock contention on swap |
|
* address space if possible. |
|
*/ |
|
if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != |
|
(next >> SWAP_ADDRESS_SPACE_SHIFT)) { |
|
/* No free swap slots available */ |
|
if (si->highest_bit <= si->lowest_bit) |
|
return; |
|
next = si->lowest_bit + |
|
prandom_u32_max(si->highest_bit - si->lowest_bit + 1); |
|
next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); |
|
next = max_t(unsigned int, next, si->lowest_bit); |
|
} |
|
this_cpu_write(*si->cluster_next_cpu, next); |
|
} |
|
|
|
static int scan_swap_map_slots(struct swap_info_struct *si, |
|
unsigned char usage, int nr, |
|
swp_entry_t slots[]) |
|
{ |
|
struct swap_cluster_info *ci; |
|
unsigned long offset; |
|
unsigned long scan_base; |
|
unsigned long last_in_cluster = 0; |
|
int latency_ration = LATENCY_LIMIT; |
|
int n_ret = 0; |
|
bool scanned_many = false; |
|
|
|
/* |
|
* We try to cluster swap pages by allocating them sequentially |
|
* in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
|
* way, however, we resort to first-free allocation, starting |
|
* a new cluster. This prevents us from scattering swap pages |
|
* all over the entire swap partition, so that we reduce |
|
* overall disk seek times between swap pages. -- sct |
|
* But we do now try to find an empty cluster. -Andrea |
|
* And we let swap pages go all over an SSD partition. Hugh |
|
*/ |
|
|
|
si->flags += SWP_SCANNING; |
|
/* |
|
* Use percpu scan base for SSD to reduce lock contention on |
|
* cluster and swap cache. For HDD, sequential access is more |
|
* important. |
|
*/ |
|
if (si->flags & SWP_SOLIDSTATE) |
|
scan_base = this_cpu_read(*si->cluster_next_cpu); |
|
else |
|
scan_base = si->cluster_next; |
|
offset = scan_base; |
|
|
|
/* SSD algorithm */ |
|
if (si->cluster_info) { |
|
if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
|
goto scan; |
|
} else if (unlikely(!si->cluster_nr--)) { |
|
if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
|
si->cluster_nr = SWAPFILE_CLUSTER - 1; |
|
goto checks; |
|
} |
|
|
|
spin_unlock(&si->lock); |
|
|
|
/* |
|
* If seek is expensive, start searching for new cluster from |
|
* start of partition, to minimize the span of allocated swap. |
|
* If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
|
* case, just handled by scan_swap_map_try_ssd_cluster() above. |
|
*/ |
|
scan_base = offset = si->lowest_bit; |
|
last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
|
|
|
/* Locate the first empty (unaligned) cluster */ |
|
for (; last_in_cluster <= si->highest_bit; offset++) { |
|
if (si->swap_map[offset]) |
|
last_in_cluster = offset + SWAPFILE_CLUSTER; |
|
else if (offset == last_in_cluster) { |
|
spin_lock(&si->lock); |
|
offset -= SWAPFILE_CLUSTER - 1; |
|
si->cluster_next = offset; |
|
si->cluster_nr = SWAPFILE_CLUSTER - 1; |
|
goto checks; |
|
} |
|
if (unlikely(--latency_ration < 0)) { |
|
cond_resched(); |
|
latency_ration = LATENCY_LIMIT; |
|
} |
|
} |
|
|
|
offset = scan_base; |
|
spin_lock(&si->lock); |
|
si->cluster_nr = SWAPFILE_CLUSTER - 1; |
|
} |
|
|
|
checks: |
|
if (si->cluster_info) { |
|
while (scan_swap_map_ssd_cluster_conflict(si, offset)) { |
|
/* take a break if we already got some slots */ |
|
if (n_ret) |
|
goto done; |
|
if (!scan_swap_map_try_ssd_cluster(si, &offset, |
|
&scan_base)) |
|
goto scan; |
|
} |
|
} |
|
if (!(si->flags & SWP_WRITEOK)) |
|
goto no_page; |
|
if (!si->highest_bit) |
|
goto no_page; |
|
if (offset > si->highest_bit) |
|
scan_base = offset = si->lowest_bit; |
|
|
|
ci = lock_cluster(si, offset); |
|
/* reuse swap entry of cache-only swap if not busy. */ |
|
if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
|
int swap_was_freed; |
|
unlock_cluster(ci); |
|
spin_unlock(&si->lock); |
|
swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); |
|
spin_lock(&si->lock); |
|
/* entry was freed successfully, try to use this again */ |
|
if (swap_was_freed) |
|
goto checks; |
|
goto scan; /* check next one */ |
|
} |
|
|
|
if (si->swap_map[offset]) { |
|
unlock_cluster(ci); |
|
if (!n_ret) |
|
goto scan; |
|
else |
|
goto done; |
|
} |
|
WRITE_ONCE(si->swap_map[offset], usage); |
|
inc_cluster_info_page(si, si->cluster_info, offset); |
|
unlock_cluster(ci); |
|
|
|
swap_range_alloc(si, offset, 1); |
|
slots[n_ret++] = swp_entry(si->type, offset); |
|
|
|
/* got enough slots or reach max slots? */ |
|
if ((n_ret == nr) || (offset >= si->highest_bit)) |
|
goto done; |
|
|
|
/* search for next available slot */ |
|
|
|
/* time to take a break? */ |
|
if (unlikely(--latency_ration < 0)) { |
|
if (n_ret) |
|
goto done; |
|
spin_unlock(&si->lock); |
|
cond_resched(); |
|
spin_lock(&si->lock); |
|
latency_ration = LATENCY_LIMIT; |
|
} |
|
|
|
/* try to get more slots in cluster */ |
|
if (si->cluster_info) { |
|
if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
|
goto checks; |
|
} else if (si->cluster_nr && !si->swap_map[++offset]) { |
|
/* non-ssd case, still more slots in cluster? */ |
|
--si->cluster_nr; |
|
goto checks; |
|
} |
|
|
|
/* |
|
* Even if there's no free clusters available (fragmented), |
|
* try to scan a little more quickly with lock held unless we |
|
* have scanned too many slots already. |
|
*/ |
|
if (!scanned_many) { |
|
unsigned long scan_limit; |
|
|
|
if (offset < scan_base) |
|
scan_limit = scan_base; |
|
else |
|
scan_limit = si->highest_bit; |
|
for (; offset <= scan_limit && --latency_ration > 0; |
|
offset++) { |
|
if (!si->swap_map[offset]) |
|
goto checks; |
|
} |
|
} |
|
|
|
done: |
|
set_cluster_next(si, offset + 1); |
|
si->flags -= SWP_SCANNING; |
|
return n_ret; |
|
|
|
scan: |
|
spin_unlock(&si->lock); |
|
while (++offset <= READ_ONCE(si->highest_bit)) { |
|
if (data_race(!si->swap_map[offset])) { |
|
spin_lock(&si->lock); |
|
goto checks; |
|
} |
|
if (vm_swap_full() && |
|
READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { |
|
spin_lock(&si->lock); |
|
goto checks; |
|
} |
|
if (unlikely(--latency_ration < 0)) { |
|
cond_resched(); |
|
latency_ration = LATENCY_LIMIT; |
|
scanned_many = true; |
|
} |
|
} |
|
offset = si->lowest_bit; |
|
while (offset < scan_base) { |
|
if (data_race(!si->swap_map[offset])) { |
|
spin_lock(&si->lock); |
|
goto checks; |
|
} |
|
if (vm_swap_full() && |
|
READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { |
|
spin_lock(&si->lock); |
|
goto checks; |
|
} |
|
if (unlikely(--latency_ration < 0)) { |
|
cond_resched(); |
|
latency_ration = LATENCY_LIMIT; |
|
scanned_many = true; |
|
} |
|
offset++; |
|
} |
|
spin_lock(&si->lock); |
|
|
|
no_page: |
|
si->flags -= SWP_SCANNING; |
|
return n_ret; |
|
} |
|
|
|
static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) |
|
{ |
|
unsigned long idx; |
|
struct swap_cluster_info *ci; |
|
unsigned long offset; |
|
|
|
/* |
|
* Should not even be attempting cluster allocations when huge |
|
* page swap is disabled. Warn and fail the allocation. |
|
*/ |
|
if (!IS_ENABLED(CONFIG_THP_SWAP)) { |
|
VM_WARN_ON_ONCE(1); |
|
return 0; |
|
} |
|
|
|
if (cluster_list_empty(&si->free_clusters)) |
|
return 0; |
|
|
|
idx = cluster_list_first(&si->free_clusters); |
|
offset = idx * SWAPFILE_CLUSTER; |
|
ci = lock_cluster(si, offset); |
|
alloc_cluster(si, idx); |
|
cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); |
|
|
|
memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER); |
|
unlock_cluster(ci); |
|
swap_range_alloc(si, offset, SWAPFILE_CLUSTER); |
|
*slot = swp_entry(si->type, offset); |
|
|
|
return 1; |
|
} |
|
|
|
static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) |
|
{ |
|
unsigned long offset = idx * SWAPFILE_CLUSTER; |
|
struct swap_cluster_info *ci; |
|
|
|
ci = lock_cluster(si, offset); |
|
memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); |
|
cluster_set_count_flag(ci, 0, 0); |
|
free_cluster(si, idx); |
|
unlock_cluster(ci); |
|
swap_range_free(si, offset, SWAPFILE_CLUSTER); |
|
} |
|
|
|
int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) |
|
{ |
|
unsigned long size = swap_entry_size(entry_size); |
|
struct swap_info_struct *si, *next; |
|
long avail_pgs; |
|
int n_ret = 0; |
|
int node; |
|
|
|
/* Only single cluster request supported */ |
|
WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); |
|
|
|
spin_lock(&swap_avail_lock); |
|
|
|
avail_pgs = atomic_long_read(&nr_swap_pages) / size; |
|
if (avail_pgs <= 0) { |
|
spin_unlock(&swap_avail_lock); |
|
goto noswap; |
|
} |
|
|
|
n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); |
|
|
|
atomic_long_sub(n_goal * size, &nr_swap_pages); |
|
|
|
start_over: |
|
node = numa_node_id(); |
|
plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { |
|
/* requeue si to after same-priority siblings */ |
|
plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); |
|
spin_unlock(&swap_avail_lock); |
|
spin_lock(&si->lock); |
|
if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
|
spin_lock(&swap_avail_lock); |
|
if (plist_node_empty(&si->avail_lists[node])) { |
|
spin_unlock(&si->lock); |
|
goto nextsi; |
|
} |
|
WARN(!si->highest_bit, |
|
"swap_info %d in list but !highest_bit\n", |
|
si->type); |
|
WARN(!(si->flags & SWP_WRITEOK), |
|
"swap_info %d in list but !SWP_WRITEOK\n", |
|
si->type); |
|
__del_from_avail_list(si); |
|
spin_unlock(&si->lock); |
|
goto nextsi; |
|
} |
|
if (size == SWAPFILE_CLUSTER) { |
|
if (si->flags & SWP_BLKDEV) |
|
n_ret = swap_alloc_cluster(si, swp_entries); |
|
} else |
|
n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
|
n_goal, swp_entries); |
|
spin_unlock(&si->lock); |
|
if (n_ret || size == SWAPFILE_CLUSTER) |
|
goto check_out; |
|
pr_debug("scan_swap_map of si %d failed to find offset\n", |
|
si->type); |
|
|
|
spin_lock(&swap_avail_lock); |
|
nextsi: |
|
/* |
|
* if we got here, it's likely that si was almost full before, |
|
* and since scan_swap_map_slots() can drop the si->lock, |
|
* multiple callers probably all tried to get a page from the |
|
* same si and it filled up before we could get one; or, the si |
|
* filled up between us dropping swap_avail_lock and taking |
|
* si->lock. Since we dropped the swap_avail_lock, the |
|
* swap_avail_head list may have been modified; so if next is |
|
* still in the swap_avail_head list then try it, otherwise |
|
* start over if we have not gotten any slots. |
|
*/ |
|
if (plist_node_empty(&next->avail_lists[node])) |
|
goto start_over; |
|
} |
|
|
|
spin_unlock(&swap_avail_lock); |
|
|
|
check_out: |
|
if (n_ret < n_goal) |
|
atomic_long_add((long)(n_goal - n_ret) * size, |
|
&nr_swap_pages); |
|
noswap: |
|
return n_ret; |
|
} |
|
|
|
static struct swap_info_struct *__swap_info_get(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *p; |
|
unsigned long offset; |
|
|
|
if (!entry.val) |
|
goto out; |
|
p = swp_swap_info(entry); |
|
if (!p) |
|
goto bad_nofile; |
|
if (data_race(!(p->flags & SWP_USED))) |
|
goto bad_device; |
|
offset = swp_offset(entry); |
|
if (offset >= p->max) |
|
goto bad_offset; |
|
return p; |
|
|
|
bad_offset: |
|
pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val); |
|
goto out; |
|
bad_device: |
|
pr_err("%s: %s%08lx\n", __func__, Unused_file, entry.val); |
|
goto out; |
|
bad_nofile: |
|
pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); |
|
out: |
|
return NULL; |
|
} |
|
|
|
static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *p; |
|
|
|
p = __swap_info_get(entry); |
|
if (!p) |
|
goto out; |
|
if (data_race(!p->swap_map[swp_offset(entry)])) |
|
goto bad_free; |
|
return p; |
|
|
|
bad_free: |
|
pr_err("%s: %s%08lx\n", __func__, Unused_offset, entry.val); |
|
out: |
|
return NULL; |
|
} |
|
|
|
static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *p; |
|
|
|
p = _swap_info_get(entry); |
|
if (p) |
|
spin_lock(&p->lock); |
|
return p; |
|
} |
|
|
|
static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
|
struct swap_info_struct *q) |
|
{ |
|
struct swap_info_struct *p; |
|
|
|
p = _swap_info_get(entry); |
|
|
|
if (p != q) { |
|
if (q != NULL) |
|
spin_unlock(&q->lock); |
|
if (p != NULL) |
|
spin_lock(&p->lock); |
|
} |
|
return p; |
|
} |
|
|
|
static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, |
|
unsigned long offset, |
|
unsigned char usage) |
|
{ |
|
unsigned char count; |
|
unsigned char has_cache; |
|
|
|
count = p->swap_map[offset]; |
|
|
|
has_cache = count & SWAP_HAS_CACHE; |
|
count &= ~SWAP_HAS_CACHE; |
|
|
|
if (usage == SWAP_HAS_CACHE) { |
|
VM_BUG_ON(!has_cache); |
|
has_cache = 0; |
|
} else if (count == SWAP_MAP_SHMEM) { |
|
/* |
|
* Or we could insist on shmem.c using a special |
|
* swap_shmem_free() and free_shmem_swap_and_cache()... |
|
*/ |
|
count = 0; |
|
} else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
|
if (count == COUNT_CONTINUED) { |
|
if (swap_count_continued(p, offset, count)) |
|
count = SWAP_MAP_MAX | COUNT_CONTINUED; |
|
else |
|
count = SWAP_MAP_MAX; |
|
} else |
|
count--; |
|
} |
|
|
|
usage = count | has_cache; |
|
if (usage) |
|
WRITE_ONCE(p->swap_map[offset], usage); |
|
else |
|
WRITE_ONCE(p->swap_map[offset], SWAP_HAS_CACHE); |
|
|
|
return usage; |
|
} |
|
|
|
/* |
|
* Check whether swap entry is valid in the swap device. If so, |
|
* return pointer to swap_info_struct, and keep the swap entry valid |
|
* via preventing the swap device from being swapoff, until |
|
* put_swap_device() is called. Otherwise return NULL. |
|
* |
|
* Notice that swapoff or swapoff+swapon can still happen before the |
|
* percpu_ref_tryget_live() in get_swap_device() or after the |
|
* percpu_ref_put() in put_swap_device() if there isn't any other way |
|
* to prevent swapoff, such as page lock, page table lock, etc. The |
|
* caller must be prepared for that. For example, the following |
|
* situation is possible. |
|
* |
|
* CPU1 CPU2 |
|
* do_swap_page() |
|
* ... swapoff+swapon |
|
* __read_swap_cache_async() |
|
* swapcache_prepare() |
|
* __swap_duplicate() |
|
* // check swap_map |
|
* // verify PTE not changed |
|
* |
|
* In __swap_duplicate(), the swap_map need to be checked before |
|
* changing partly because the specified swap entry may be for another |
|
* swap device which has been swapoff. And in do_swap_page(), after |
|
* the page is read from the swap device, the PTE is verified not |
|
* changed with the page table locked to check whether the swap device |
|
* has been swapoff or swapoff+swapon. |
|
*/ |
|
struct swap_info_struct *get_swap_device(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *si; |
|
unsigned long offset; |
|
|
|
if (!entry.val) |
|
goto out; |
|
si = swp_swap_info(entry); |
|
if (!si) |
|
goto bad_nofile; |
|
if (!percpu_ref_tryget_live(&si->users)) |
|
goto out; |
|
/* |
|
* Guarantee the si->users are checked before accessing other |
|
* fields of swap_info_struct. |
|
* |
|
* Paired with the spin_unlock() after setup_swap_info() in |
|
* enable_swap_info(). |
|
*/ |
|
smp_rmb(); |
|
offset = swp_offset(entry); |
|
if (offset >= si->max) |
|
goto put_out; |
|
|
|
return si; |
|
bad_nofile: |
|
pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); |
|
out: |
|
return NULL; |
|
put_out: |
|
percpu_ref_put(&si->users); |
|
return NULL; |
|
} |
|
|
|
static unsigned char __swap_entry_free(struct swap_info_struct *p, |
|
swp_entry_t entry) |
|
{ |
|
struct swap_cluster_info *ci; |
|
unsigned long offset = swp_offset(entry); |
|
unsigned char usage; |
|
|
|
ci = lock_cluster_or_swap_info(p, offset); |
|
usage = __swap_entry_free_locked(p, offset, 1); |
|
unlock_cluster_or_swap_info(p, ci); |
|
if (!usage) |
|
free_swap_slot(entry); |
|
|
|
return usage; |
|
} |
|
|
|
static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) |
|
{ |
|
struct swap_cluster_info *ci; |
|
unsigned long offset = swp_offset(entry); |
|
unsigned char count; |
|
|
|
ci = lock_cluster(p, offset); |
|
count = p->swap_map[offset]; |
|
VM_BUG_ON(count != SWAP_HAS_CACHE); |
|
p->swap_map[offset] = 0; |
|
dec_cluster_info_page(p, p->cluster_info, offset); |
|
unlock_cluster(ci); |
|
|
|
mem_cgroup_uncharge_swap(entry, 1); |
|
swap_range_free(p, offset, 1); |
|
} |
|
|
|
/* |
|
* Caller has made sure that the swap device corresponding to entry |
|
* is still around or has not been recycled. |
|
*/ |
|
void swap_free(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *p; |
|
|
|
p = _swap_info_get(entry); |
|
if (p) |
|
__swap_entry_free(p, entry); |
|
} |
|
|
|
/* |
|
* Called after dropping swapcache to decrease refcnt to swap entries. |
|
*/ |
|
void put_swap_page(struct page *page, swp_entry_t entry) |
|
{ |
|
unsigned long offset = swp_offset(entry); |
|
unsigned long idx = offset / SWAPFILE_CLUSTER; |
|
struct swap_cluster_info *ci; |
|
struct swap_info_struct *si; |
|
unsigned char *map; |
|
unsigned int i, free_entries = 0; |
|
unsigned char val; |
|
int size = swap_entry_size(thp_nr_pages(page)); |
|
|
|
si = _swap_info_get(entry); |
|
if (!si) |
|
return; |
|
|
|
ci = lock_cluster_or_swap_info(si, offset); |
|
if (size == SWAPFILE_CLUSTER) { |
|
VM_BUG_ON(!cluster_is_huge(ci)); |
|
map = si->swap_map + offset; |
|
for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
|
val = map[i]; |
|
VM_BUG_ON(!(val & SWAP_HAS_CACHE)); |
|
if (val == SWAP_HAS_CACHE) |
|
free_entries++; |
|
} |
|
cluster_clear_huge(ci); |
|
if (free_entries == SWAPFILE_CLUSTER) { |
|
unlock_cluster_or_swap_info(si, ci); |
|
spin_lock(&si->lock); |
|
mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); |
|
swap_free_cluster(si, idx); |
|
spin_unlock(&si->lock); |
|
return; |
|
} |
|
} |
|
for (i = 0; i < size; i++, entry.val++) { |
|
if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) { |
|
unlock_cluster_or_swap_info(si, ci); |
|
free_swap_slot(entry); |
|
if (i == size - 1) |
|
return; |
|
lock_cluster_or_swap_info(si, offset); |
|
} |
|
} |
|
unlock_cluster_or_swap_info(si, ci); |
|
} |
|
|
|
#ifdef CONFIG_THP_SWAP |
|
int split_swap_cluster(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *si; |
|
struct swap_cluster_info *ci; |
|
unsigned long offset = swp_offset(entry); |
|
|
|
si = _swap_info_get(entry); |
|
if (!si) |
|
return -EBUSY; |
|
ci = lock_cluster(si, offset); |
|
cluster_clear_huge(ci); |
|
unlock_cluster(ci); |
|
return 0; |
|
} |
|
#endif |
|
|
|
static int swp_entry_cmp(const void *ent1, const void *ent2) |
|
{ |
|
const swp_entry_t *e1 = ent1, *e2 = ent2; |
|
|
|
return (int)swp_type(*e1) - (int)swp_type(*e2); |
|
} |
|
|
|
void swapcache_free_entries(swp_entry_t *entries, int n) |
|
{ |
|
struct swap_info_struct *p, *prev; |
|
int i; |
|
|
|
if (n <= 0) |
|
return; |
|
|
|
prev = NULL; |
|
p = NULL; |
|
|
|
/* |
|
* Sort swap entries by swap device, so each lock is only taken once. |
|
* nr_swapfiles isn't absolutely correct, but the overhead of sort() is |
|
* so low that it isn't necessary to optimize further. |
|
*/ |
|
if (nr_swapfiles > 1) |
|
sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); |
|
for (i = 0; i < n; ++i) { |
|
p = swap_info_get_cont(entries[i], prev); |
|
if (p) |
|
swap_entry_free(p, entries[i]); |
|
prev = p; |
|
} |
|
if (p) |
|
spin_unlock(&p->lock); |
|
} |
|
|
|
/* |
|
* How many references to page are currently swapped out? |
|
* This does not give an exact answer when swap count is continued, |
|
* but does include the high COUNT_CONTINUED flag to allow for that. |
|
*/ |
|
int page_swapcount(struct page *page) |
|
{ |
|
int count = 0; |
|
struct swap_info_struct *p; |
|
struct swap_cluster_info *ci; |
|
swp_entry_t entry; |
|
unsigned long offset; |
|
|
|
entry.val = page_private(page); |
|
p = _swap_info_get(entry); |
|
if (p) { |
|
offset = swp_offset(entry); |
|
ci = lock_cluster_or_swap_info(p, offset); |
|
count = swap_count(p->swap_map[offset]); |
|
unlock_cluster_or_swap_info(p, ci); |
|
} |
|
return count; |
|
} |
|
|
|
int __swap_count(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *si; |
|
pgoff_t offset = swp_offset(entry); |
|
int count = 0; |
|
|
|
si = get_swap_device(entry); |
|
if (si) { |
|
count = swap_count(si->swap_map[offset]); |
|
put_swap_device(si); |
|
} |
|
return count; |
|
} |
|
|
|
static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
|
{ |
|
int count = 0; |
|
pgoff_t offset = swp_offset(entry); |
|
struct swap_cluster_info *ci; |
|
|
|
ci = lock_cluster_or_swap_info(si, offset); |
|
count = swap_count(si->swap_map[offset]); |
|
unlock_cluster_or_swap_info(si, ci); |
|
return count; |
|
} |
|
|
|
/* |
|
* How many references to @entry are currently swapped out? |
|
* This does not give an exact answer when swap count is continued, |
|
* but does include the high COUNT_CONTINUED flag to allow for that. |
|
*/ |
|
int __swp_swapcount(swp_entry_t entry) |
|
{ |
|
int count = 0; |
|
struct swap_info_struct *si; |
|
|
|
si = get_swap_device(entry); |
|
if (si) { |
|
count = swap_swapcount(si, entry); |
|
put_swap_device(si); |
|
} |
|
return count; |
|
} |
|
|
|
/* |
|
* How many references to @entry are currently swapped out? |
|
* This considers COUNT_CONTINUED so it returns exact answer. |
|
*/ |
|
int swp_swapcount(swp_entry_t entry) |
|
{ |
|
int count, tmp_count, n; |
|
struct swap_info_struct *p; |
|
struct swap_cluster_info *ci; |
|
struct page *page; |
|
pgoff_t offset; |
|
unsigned char *map; |
|
|
|
p = _swap_info_get(entry); |
|
if (!p) |
|
return 0; |
|
|
|
offset = swp_offset(entry); |
|
|
|
ci = lock_cluster_or_swap_info(p, offset); |
|
|
|
count = swap_count(p->swap_map[offset]); |
|
if (!(count & COUNT_CONTINUED)) |
|
goto out; |
|
|
|
count &= ~COUNT_CONTINUED; |
|
n = SWAP_MAP_MAX + 1; |
|
|
|
page = vmalloc_to_page(p->swap_map + offset); |
|
offset &= ~PAGE_MASK; |
|
VM_BUG_ON(page_private(page) != SWP_CONTINUED); |
|
|
|
do { |
|
page = list_next_entry(page, lru); |
|
map = kmap_atomic(page); |
|
tmp_count = map[offset]; |
|
kunmap_atomic(map); |
|
|
|
count += (tmp_count & ~COUNT_CONTINUED) * n; |
|
n *= (SWAP_CONT_MAX + 1); |
|
} while (tmp_count & COUNT_CONTINUED); |
|
out: |
|
unlock_cluster_or_swap_info(p, ci); |
|
return count; |
|
} |
|
|
|
static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, |
|
swp_entry_t entry) |
|
{ |
|
struct swap_cluster_info *ci; |
|
unsigned char *map = si->swap_map; |
|
unsigned long roffset = swp_offset(entry); |
|
unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); |
|
int i; |
|
bool ret = false; |
|
|
|
ci = lock_cluster_or_swap_info(si, offset); |
|
if (!ci || !cluster_is_huge(ci)) { |
|
if (swap_count(map[roffset])) |
|
ret = true; |
|
goto unlock_out; |
|
} |
|
for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
|
if (swap_count(map[offset + i])) { |
|
ret = true; |
|
break; |
|
} |
|
} |
|
unlock_out: |
|
unlock_cluster_or_swap_info(si, ci); |
|
return ret; |
|
} |
|
|
|
static bool page_swapped(struct page *page) |
|
{ |
|
swp_entry_t entry; |
|
struct swap_info_struct *si; |
|
|
|
if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) |
|
return page_swapcount(page) != 0; |
|
|
|
page = compound_head(page); |
|
entry.val = page_private(page); |
|
si = _swap_info_get(entry); |
|
if (si) |
|
return swap_page_trans_huge_swapped(si, entry); |
|
return false; |
|
} |
|
|
|
static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, |
|
int *total_swapcount) |
|
{ |
|
int i, map_swapcount, _total_mapcount, _total_swapcount; |
|
unsigned long offset = 0; |
|
struct swap_info_struct *si; |
|
struct swap_cluster_info *ci = NULL; |
|
unsigned char *map = NULL; |
|
int mapcount, swapcount = 0; |
|
|
|
/* hugetlbfs shouldn't call it */ |
|
VM_BUG_ON_PAGE(PageHuge(page), page); |
|
|
|
if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) { |
|
mapcount = page_trans_huge_mapcount(page, total_mapcount); |
|
if (PageSwapCache(page)) |
|
swapcount = page_swapcount(page); |
|
if (total_swapcount) |
|
*total_swapcount = swapcount; |
|
return mapcount + swapcount; |
|
} |
|
|
|
page = compound_head(page); |
|
|
|
_total_mapcount = _total_swapcount = map_swapcount = 0; |
|
if (PageSwapCache(page)) { |
|
swp_entry_t entry; |
|
|
|
entry.val = page_private(page); |
|
si = _swap_info_get(entry); |
|
if (si) { |
|
map = si->swap_map; |
|
offset = swp_offset(entry); |
|
} |
|
} |
|
if (map) |
|
ci = lock_cluster(si, offset); |
|
for (i = 0; i < HPAGE_PMD_NR; i++) { |
|
mapcount = atomic_read(&page[i]._mapcount) + 1; |
|
_total_mapcount += mapcount; |
|
if (map) { |
|
swapcount = swap_count(map[offset + i]); |
|
_total_swapcount += swapcount; |
|
} |
|
map_swapcount = max(map_swapcount, mapcount + swapcount); |
|
} |
|
unlock_cluster(ci); |
|
if (PageDoubleMap(page)) { |
|
map_swapcount -= 1; |
|
_total_mapcount -= HPAGE_PMD_NR; |
|
} |
|
mapcount = compound_mapcount(page); |
|
map_swapcount += mapcount; |
|
_total_mapcount += mapcount; |
|
if (total_mapcount) |
|
*total_mapcount = _total_mapcount; |
|
if (total_swapcount) |
|
*total_swapcount = _total_swapcount; |
|
|
|
return map_swapcount; |
|
} |
|
|
|
/* |
|
* We can write to an anon page without COW if there are no other references |
|
* to it. And as a side-effect, free up its swap: because the old content |
|
* on disk will never be read, and seeking back there to write new content |
|
* later would only waste time away from clustering. |
|
* |
|
* NOTE: total_map_swapcount should not be relied upon by the caller if |
|
* reuse_swap_page() returns false, but it may be always overwritten |
|
* (see the other implementation for CONFIG_SWAP=n). |
|
*/ |
|
bool reuse_swap_page(struct page *page, int *total_map_swapcount) |
|
{ |
|
int count, total_mapcount, total_swapcount; |
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
if (unlikely(PageKsm(page))) |
|
return false; |
|
count = page_trans_huge_map_swapcount(page, &total_mapcount, |
|
&total_swapcount); |
|
if (total_map_swapcount) |
|
*total_map_swapcount = total_mapcount + total_swapcount; |
|
if (count == 1 && PageSwapCache(page) && |
|
(likely(!PageTransCompound(page)) || |
|
/* The remaining swap count will be freed soon */ |
|
total_swapcount == page_swapcount(page))) { |
|
if (!PageWriteback(page)) { |
|
page = compound_head(page); |
|
delete_from_swap_cache(page); |
|
SetPageDirty(page); |
|
} else { |
|
swp_entry_t entry; |
|
struct swap_info_struct *p; |
|
|
|
entry.val = page_private(page); |
|
p = swap_info_get(entry); |
|
if (p->flags & SWP_STABLE_WRITES) { |
|
spin_unlock(&p->lock); |
|
return false; |
|
} |
|
spin_unlock(&p->lock); |
|
} |
|
} |
|
|
|
return count <= 1; |
|
} |
|
|
|
/* |
|
* If swap is getting full, or if there are no more mappings of this page, |
|
* then try_to_free_swap is called to free its swap space. |
|
*/ |
|
int try_to_free_swap(struct page *page) |
|
{ |
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
|
|
if (!PageSwapCache(page)) |
|
return 0; |
|
if (PageWriteback(page)) |
|
return 0; |
|
if (page_swapped(page)) |
|
return 0; |
|
|
|
/* |
|
* Once hibernation has begun to create its image of memory, |
|
* there's a danger that one of the calls to try_to_free_swap() |
|
* - most probably a call from __try_to_reclaim_swap() while |
|
* hibernation is allocating its own swap pages for the image, |
|
* but conceivably even a call from memory reclaim - will free |
|
* the swap from a page which has already been recorded in the |
|
* image as a clean swapcache page, and then reuse its swap for |
|
* another page of the image. On waking from hibernation, the |
|
* original page might be freed under memory pressure, then |
|
* later read back in from swap, now with the wrong data. |
|
* |
|
* Hibernation suspends storage while it is writing the image |
|
* to disk so check that here. |
|
*/ |
|
if (pm_suspended_storage()) |
|
return 0; |
|
|
|
page = compound_head(page); |
|
delete_from_swap_cache(page); |
|
SetPageDirty(page); |
|
return 1; |
|
} |
|
|
|
/* |
|
* Free the swap entry like above, but also try to |
|
* free the page cache entry if it is the last user. |
|
*/ |
|
int free_swap_and_cache(swp_entry_t entry) |
|
{ |
|
struct swap_info_struct *p; |
|
unsigned char count; |
|
|
|
if (non_swap_entry(entry)) |
|
return 1; |
|
|
|
p = _swap_info_get(entry); |
|
if (p) { |
|
count = __swap_entry_free(p, entry); |
|
if (count == SWAP_HAS_CACHE && |
|
!swap_page_trans_huge_swapped(p, entry)) |
|
__try_to_reclaim_swap(p, swp_offset(entry), |
|
TTRS_UNMAPPED | TTRS_FULL); |
|
} |
|
return p != NULL; |
|
} |
|
|
|
#ifdef CONFIG_HIBERNATION |
|
|
|
swp_entry_t get_swap_page_of_type(int type) |
|
{ |
|
struct swap_info_struct *si = swap_type_to_swap_info(type); |
|
swp_entry_t entry = {0}; |
|
|
|
if (!si) |
|
goto fail; |
|
|
|
/* This is called for allocating swap entry, not cache */ |
|
spin_lock(&si->lock); |
|
if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry)) |
|
atomic_long_dec(&nr_swap_pages); |
|
spin_unlock(&si->lock); |
|
fail: |
|
return entry; |
|
} |
|
|
|
/* |
|
* Find the swap type that corresponds to given device (if any). |
|
* |
|
* @offset - number of the PAGE_SIZE-sized block of the device, starting |
|
* from 0, in which the swap header is expected to be located. |
|
* |
|
* This is needed for the suspend to disk (aka swsusp). |
|
*/ |
|
int swap_type_of(dev_t device, sector_t offset) |
|
{ |
|
int type; |
|
|
|
if (!device) |
|
return -1; |
|
|
|
spin_lock(&swap_lock); |
|
for (type = 0; type < nr_swapfiles; type++) { |
|
struct swap_info_struct *sis = swap_info[type]; |
|
|
|
if (!(sis->flags & SWP_WRITEOK)) |
|
continue; |
|
|
|
if (device == sis->bdev->bd_dev) { |
|
struct swap_extent *se = first_se(sis); |
|
|
|
if (se->start_block == offset) { |
|
spin_unlock(&swap_lock); |
|
return type; |
|
} |
|
} |
|
} |
|
spin_unlock(&swap_lock); |
|
return -ENODEV; |
|
} |
|
|
|
int find_first_swap(dev_t *device) |
|
{ |
|
int type; |
|
|
|
spin_lock(&swap_lock); |
|
for (type = 0; type < nr_swapfiles; type++) { |
|
struct swap_info_struct *sis = swap_info[type]; |
|
|
|
if (!(sis->flags & SWP_WRITEOK)) |
|
continue; |
|
*device = sis->bdev->bd_dev; |
|
spin_unlock(&swap_lock); |
|
return type; |
|
} |
|
spin_unlock(&swap_lock); |
|
return -ENODEV; |
|
} |
|
|
|
/* |
|
* Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
|
* corresponding to given index in swap_info (swap type). |
|
*/ |
|
sector_t swapdev_block(int type, pgoff_t offset) |
|
{ |
|
struct swap_info_struct *si = swap_type_to_swap_info(type); |
|
struct swap_extent *se; |
|
|
|
if (!si || !(si->flags & SWP_WRITEOK)) |
|
return 0; |
|
se = offset_to_swap_extent(si, offset); |
|
return se->start_block + (offset - se->start_page); |
|
} |
|
|
|
/* |
|
* Return either the total number of swap pages of given type, or the number |
|
* of free pages of that type (depending on @free) |
|
* |
|
* This is needed for software suspend |
|
*/ |
|
unsigned int count_swap_pages(int type, int free) |
|
{ |
|
unsigned int n = 0; |
|
|
|
spin_lock(&swap_lock); |
|
if ((unsigned int)type < nr_swapfiles) { |
|
struct swap_info_struct *sis = swap_info[type]; |
|
|
|
spin_lock(&sis->lock); |
|
if (sis->flags & SWP_WRITEOK) { |
|
n = sis->pages; |
|
if (free) |
|
n -= sis->inuse_pages; |
|
} |
|
spin_unlock(&sis->lock); |
|
} |
|
spin_unlock(&swap_lock); |
|
return n; |
|
} |
|
#endif /* CONFIG_HIBERNATION */ |
|
|
|
static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
|
{ |
|
return pte_same(pte_swp_clear_flags(pte), swp_pte); |
|
} |
|
|
|
/* |
|
* No need to decide whether this PTE shares the swap entry with others, |
|
* just let do_wp_page work it out if a write is requested later - to |
|
* force COW, vm_page_prot omits write permission from any private vma. |
|
*/ |
|
static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
|
unsigned long addr, swp_entry_t entry, struct page *page) |
|
{ |
|
struct page *swapcache; |
|
spinlock_t *ptl; |
|
pte_t *pte; |
|
int ret = 1; |
|
|
|
swapcache = page; |
|
page = ksm_might_need_to_copy(page, vma, addr); |
|
if (unlikely(!page)) |
|
return -ENOMEM; |
|
|
|
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
|
if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { |
|
ret = 0; |
|
goto out; |
|
} |
|
|
|
dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
|
inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
|
get_page(page); |
|
set_pte_at(vma->vm_mm, addr, pte, |
|
pte_mkold(mk_pte(page, vma->vm_page_prot))); |
|
if (page == swapcache) { |
|
page_add_anon_rmap(page, vma, addr, false); |
|
} else { /* ksm created a completely new copy */ |
|
page_add_new_anon_rmap(page, vma, addr, false); |
|
lru_cache_add_inactive_or_unevictable(page, vma); |
|
} |
|
swap_free(entry); |
|
out: |
|
pte_unmap_unlock(pte, ptl); |
|
if (page != swapcache) { |
|
unlock_page(page); |
|
put_page(page); |
|
} |
|
return ret; |
|
} |
|
|
|
static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
|
unsigned long addr, unsigned long end, |
|
unsigned int type, bool frontswap, |
|
unsigned long *fs_pages_to_unuse) |
|
{ |
|
struct page *page; |
|
swp_entry_t entry; |
|
pte_t *pte; |
|
struct swap_info_struct *si; |
|
unsigned long offset; |
|
int ret = 0; |
|
volatile unsigned char *swap_map; |
|
|
|
si = swap_info[type]; |
|
pte = pte_offset_map(pmd, addr); |
|
do { |
|
if (!is_swap_pte(*pte)) |
|
continue; |
|
|
|
entry = pte_to_swp_entry(*pte); |
|
if (swp_type(entry) != type) |
|
continue; |
|
|
|
offset = swp_offset(entry); |
|
if (frontswap && !frontswap_test(si, offset)) |
|
continue; |
|
|
|
pte_unmap(pte); |
|
swap_map = &si->swap_map[offset]; |
|
page = lookup_swap_cache(entry, vma, addr); |
|
if (!page) { |
|
struct vm_fault vmf = { |
|
.vma = vma, |
|
.address = addr, |
|
.pmd = pmd, |
|
}; |
|
|
|
page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
|
&vmf); |
|
} |
|
if (!page) { |
|
if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD) |
|
goto try_next; |
|
return -ENOMEM; |
|
} |
|
|
|
lock_page(page); |
|
wait_on_page_writeback(page); |
|
ret = unuse_pte(vma, pmd, addr, entry, page); |
|
if (ret < 0) { |
|
unlock_page(page); |
|
put_page(page); |
|
goto out; |
|
} |
|
|
|
try_to_free_swap(page); |
|
unlock_page(page); |
|
put_page(page); |
|
|
|
if (*fs_pages_to_unuse && !--(*fs_pages_to_unuse)) { |
|
ret = FRONTSWAP_PAGES_UNUSED; |
|
goto out; |
|
} |
|
try_next: |
|
pte = pte_offset_map(pmd, addr); |
|
} while (pte++, addr += PAGE_SIZE, addr != end); |
|
pte_unmap(pte - 1); |
|
|
|
ret = 0; |
|
out: |
|
return ret; |
|
} |
|
|
|
static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
|
unsigned long addr, unsigned long end, |
|
unsigned int type, bool frontswap, |
|
unsigned long *fs_pages_to_unuse) |
|
{ |
|
pmd_t *pmd; |
|
unsigned long next; |
|
int ret; |
|
|
|
pmd = pmd_offset(pud, addr); |
|
do { |
|
cond_resched(); |
|
next = pmd_addr_end(addr, end); |
|
if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
|
continue; |
|
ret = unuse_pte_range(vma, pmd, addr, next, type, |
|
frontswap, fs_pages_to_unuse); |
|
if (ret) |
|
return ret; |
|
} while (pmd++, addr = next, addr != end); |
|
return 0; |
|
} |
|
|
|
static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
|
unsigned long addr, unsigned long end, |
|
unsigned int type, bool frontswap, |
|
unsigned long *fs_pages_to_unuse) |
|
{ |
|
pud_t *pud; |
|
unsigned long next; |
|
int ret; |
|
|
|
pud = pud_offset(p4d, addr); |
|
do { |
|
next = pud_addr_end(addr, end); |
|
if (pud_none_or_clear_bad(pud)) |
|
continue; |
|
ret = unuse_pmd_range(vma, pud, addr, next, type, |
|
frontswap, fs_pages_to_unuse); |
|
if (ret) |
|
return ret; |
|
} while (pud++, addr = next, addr != end); |
|
return 0; |
|
} |
|
|
|
static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
|
unsigned long addr, unsigned long end, |
|
unsigned int type, bool frontswap, |
|
unsigned long *fs_pages_to_unuse) |
|
{ |
|
p4d_t *p4d; |
|
unsigned long next; |
|
int ret; |
|
|
|
p4d = p4d_offset(pgd, addr); |
|
do { |
|
next = p4d_addr_end(addr, end); |
|
if (p4d_none_or_clear_bad(p4d)) |
|
continue; |
|
ret = unuse_pud_range(vma, p4d, addr, next, type, |
|
frontswap, fs_pages_to_unuse); |
|
if (ret) |
|
return ret; |
|
} while (p4d++, addr = next, addr != end); |
|
return 0; |
|
} |
|
|
|
static int unuse_vma(struct vm_area_struct *vma, unsigned int type, |
|
bool frontswap, unsigned long *fs_pages_to_unuse) |
|
{ |
|
pgd_t *pgd; |
|
unsigned long addr, end, next; |
|
int ret; |
|
|
|
addr = vma->vm_start; |
|
end = vma->vm_end; |
|
|
|
pgd = pgd_offset(vma->vm_mm, addr); |
|
do { |
|
next = pgd_addr_end(addr, end); |
|
if (pgd_none_or_clear_bad(pgd)) |
|
continue; |
|
ret = unuse_p4d_range(vma, pgd, addr, next, type, |
|
frontswap, fs_pages_to_unuse); |
|
if (ret) |
|
return ret; |
|
} while (pgd++, addr = next, addr != end); |
|
return 0; |
|
} |
|
|
|
static int unuse_mm(struct mm_struct *mm, unsigned int type, |
|
bool frontswap, unsigned long *fs_pages_to_unuse) |
|
{ |
|
struct vm_area_struct *vma; |
|
int ret = 0; |
|
|
|
mmap_read_lock(mm); |
|
for (vma = mm->mmap; vma; vma = vma->vm_next) { |
|
if (vma->anon_vma) { |
|
ret = unuse_vma(vma, type, frontswap, |
|
fs_pages_to_unuse); |
|
if (ret) |
|
break; |
|
} |
|
cond_resched(); |
|
} |
|
mmap_read_unlock(mm); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Scan swap_map (or frontswap_map if frontswap parameter is true) |
|
* from current position to next entry still in use. Return 0 |
|
* if there are no inuse entries after prev till end of the map. |
|
*/ |
|
static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
|
unsigned int prev, bool frontswap) |
|
{ |
|
unsigned int i; |
|
unsigned char count; |
|
|
|
/* |
|
* No need for swap_lock here: we're just looking |
|
* for whether an entry is in use, not modifying it; false |
|
* hits are okay, and sys_swapoff() has already prevented new |
|
* allocations from this area (while holding swap_lock). |
|
*/ |
|
for (i = prev + 1; i < si->max; i++) { |
|
count = READ_ONCE(si->swap_map[i]); |
|
if (count && swap_count(count) != SWAP_MAP_BAD) |
|
if (!frontswap || frontswap_test(si, i)) |
|
break; |
|
if ((i % LATENCY_LIMIT) == 0) |
|
cond_resched(); |
|
} |
|
|
|
if (i == si->max) |
|
i = 0; |
|
|
|
return i; |
|
} |
|
|
|
/* |
|
* If the boolean frontswap is true, only unuse pages_to_unuse pages; |
|
* pages_to_unuse==0 means all pages; ignored if frontswap is false |
|
*/ |
|
int try_to_unuse(unsigned int type, bool frontswap, |
|
unsigned long pages_to_unuse) |
|
{ |
|
struct mm_struct *prev_mm; |
|
struct mm_struct *mm; |
|
struct list_head *p; |
|
int retval = 0; |
|
struct swap_info_struct *si = swap_info[type]; |
|
struct page *page; |
|
swp_entry_t entry; |
|
unsigned int i; |
|
|
|
if (!READ_ONCE(si->inuse_pages)) |
|
return 0; |
|
|
|
if (!frontswap) |
|
pages_to_unuse = 0; |
|
|
|
retry: |
|
retval = shmem_unuse(type, frontswap, &pages_to_unuse); |
|
if (retval) |
|
goto out; |
|
|
|
prev_mm = &init_mm; |
|
mmget(prev_mm); |
|
|
|
spin_lock(&mmlist_lock); |
|
p = &init_mm.mmlist; |
|
while (READ_ONCE(si->inuse_pages) && |
|
!signal_pending(current) && |
|
(p = p->next) != &init_mm.mmlist) { |
|
|
|
mm = list_entry(p, struct mm_struct, mmlist); |
|
if (!mmget_not_zero(mm)) |
|
continue; |
|
spin_unlock(&mmlist_lock); |
|
mmput(prev_mm); |
|
prev_mm = mm; |
|
retval = unuse_mm(mm, type, frontswap, &pages_to_unuse); |
|
|
|
if (retval) { |
|
mmput(prev_mm); |
|
goto out; |
|
} |
|
|
|
/* |
|
* Make sure that we aren't completely killing |
|
* interactive performance. |
|
*/ |
|
cond_resched(); |
|
spin_lock(&mmlist_lock); |
|
} |
|
spin_unlock(&mmlist_lock); |
|
|
|
mmput(prev_mm); |
|
|
|
i = 0; |
|
while (READ_ONCE(si->inuse_pages) && |
|
!signal_pending(current) && |
|
(i = find_next_to_unuse(si, i, frontswap)) != 0) { |
|
|
|
entry = swp_entry(type, i); |
|
page = find_get_page(swap_address_space(entry), i); |
|
if (!page) |
|
continue; |
|
|
|
/* |
|
* It is conceivable that a racing task removed this page from |
|
* swap cache just before we acquired the page lock. The page |
|
* might even be back in swap cache on another swap area. But |
|
* that is okay, try_to_free_swap() only removes stale pages. |
|
*/ |
|
lock_page(page); |
|
wait_on_page_writeback(page); |
|
try_to_free_swap(page); |
|
unlock_page(page); |
|
put_page(page); |
|
|
|
/* |
|
* For frontswap, we just need to unuse pages_to_unuse, if |
|
* it was specified. Need not check frontswap again here as |
|
* we already zeroed out pages_to_unuse if not frontswap. |
|
*/ |
|
if (pages_to_unuse && --pages_to_unuse == 0) |
|
goto out; |
|
} |
|
|
|
/* |
|
* Lets check again to see if there are still swap entries in the map. |
|
* If yes, we would need to do retry the unuse logic again. |
|
* Under global memory pressure, swap entries can be reinserted back |
|
* into process space after the mmlist loop above passes over them. |
|
* |
|
* Limit the number of retries? No: when mmget_not_zero() above fails, |
|
* that mm is likely to be freeing swap from exit_mmap(), which proceeds |
|
* at its own independent pace; and even shmem_writepage() could have |
|
* been preempted after get_swap_page(), temporarily hiding that swap. |
|
* It's easy and robust (though cpu-intensive) just to keep retrying. |
|
*/ |
|
if (READ_ONCE(si->inuse_pages)) { |
|
if (!signal_pending(current)) |
|
goto retry; |
|
retval = -EINTR; |
|
} |
|
out: |
|
return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval; |
|
} |
|
|
|
/* |
|
* After a successful try_to_unuse, if no swap is now in use, we know |
|
* we can empty the mmlist. swap_lock must be held on entry and exit. |
|
* Note that mmlist_lock nests inside swap_lock, and an mm must be |
|
* added to the mmlist just after page_duplicate - before would be racy. |
|
*/ |
|
static void drain_mmlist(void) |
|
{ |
|
struct list_head *p, *next; |
|
unsigned int type; |
|
|
|
for (type = 0; type < nr_swapfiles; type++) |
|
if (swap_info[type]->inuse_pages) |
|
return; |
|
spin_lock(&mmlist_lock); |
|
list_for_each_safe(p, next, &init_mm.mmlist) |
|
list_del_init(p); |
|
spin_unlock(&mmlist_lock); |
|
} |
|
|
|
/* |
|
* Free all of a swapdev's extent information |
|
*/ |
|
static void destroy_swap_extents(struct swap_info_struct *sis) |
|
{ |
|
while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { |
|
struct rb_node *rb = sis->swap_extent_root.rb_node; |
|
struct swap_extent *se = rb_entry(rb, struct swap_extent, rb_node); |
|
|
|
rb_erase(rb, &sis->swap_extent_root); |
|
kfree(se); |
|
} |
|
|
|
if (sis->flags & SWP_ACTIVATED) { |
|
struct file *swap_file = sis->swap_file; |
|
struct address_space *mapping = swap_file->f_mapping; |
|
|
|
sis->flags &= ~SWP_ACTIVATED; |
|
if (mapping->a_ops->swap_deactivate) |
|
mapping->a_ops->swap_deactivate(swap_file); |
|
} |
|
} |
|
|
|
/* |
|
* Add a block range (and the corresponding page range) into this swapdev's |
|
* extent tree. |
|
* |
|
* This function rather assumes that it is called in ascending page order. |
|
*/ |
|
int |
|
add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
|
unsigned long nr_pages, sector_t start_block) |
|
{ |
|
struct rb_node **link = &sis->swap_extent_root.rb_node, *parent = NULL; |
|
struct swap_extent *se; |
|
struct swap_extent *new_se; |
|
|
|
/* |
|
* place the new node at the right most since the |
|
* function is called in ascending page order. |
|
*/ |
|
while (*link) { |
|
parent = *link; |
|
link = &parent->rb_right; |
|
} |
|
|
|
if (parent) { |
|
se = rb_entry(parent, struct swap_extent, rb_node); |
|
BUG_ON(se->start_page + se->nr_pages != start_page); |
|
if (se->start_block + se->nr_pages == start_block) { |
|
/* Merge it */ |
|
se->nr_pages += nr_pages; |
|
return 0; |
|
} |
|
} |
|
|
|
/* No merge, insert a new extent. */ |
|
new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
|
if (new_se == NULL) |
|
return -ENOMEM; |
|
new_se->start_page = start_page; |
|
new_se->nr_pages = nr_pages; |
|
new_se->start_block = start_block; |
|
|
|
rb_link_node(&new_se->rb_node, parent, link); |
|
rb_insert_color(&new_se->rb_node, &sis->swap_extent_root); |
|
return 1; |
|
} |
|
EXPORT_SYMBOL_GPL(add_swap_extent); |
|
|
|
/* |
|
* A `swap extent' is a simple thing which maps a contiguous range of pages |
|
* onto a contiguous range of disk blocks. An ordered list of swap extents |
|
* is built at swapon time and is then used at swap_writepage/swap_readpage |
|
* time for locating where on disk a page belongs. |
|
* |
|
* If the swapfile is an S_ISBLK block device, a single extent is installed. |
|
* This is done so that the main operating code can treat S_ISBLK and S_ISREG |
|
* swap files identically. |
|
* |
|
* Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
|
* extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
|
* swapfiles are handled *identically* after swapon time. |
|
* |
|
* For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
|
* and will parse them into an ordered extent list, in PAGE_SIZE chunks. If |
|
* some stray blocks are found which do not fall within the PAGE_SIZE alignment |
|
* requirements, they are simply tossed out - we will never use those blocks |
|
* for swapping. |
|
* |
|
* For all swap devices we set S_SWAPFILE across the life of the swapon. This |
|
* prevents users from writing to the swap device, which will corrupt memory. |
|
* |
|
* The amount of disk space which a single swap extent represents varies. |
|
* Typically it is in the 1-4 megabyte range. So we can have hundreds of |
|
* extents in the list. To avoid much list walking, we cache the previous |
|
* search location in `curr_swap_extent', and start new searches from there. |
|
* This is extremely effective. The average number of iterations in |
|
* map_swap_page() has been measured at about 0.3 per page. - akpm. |
|
*/ |
|
static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
|
{ |
|
struct file *swap_file = sis->swap_file; |
|
struct address_space *mapping = swap_file->f_mapping; |
|
struct inode *inode = mapping->host; |
|
int ret; |
|
|
|
if (S_ISBLK(inode->i_mode)) { |
|
ret = add_swap_extent(sis, 0, sis->max, 0); |
|
*span = sis->pages; |
|
return ret; |
|
} |
|
|
|
if (mapping->a_ops->swap_activate) { |
|
ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
|
if (ret >= 0) |
|
sis->flags |= SWP_ACTIVATED; |
|
if (!ret) { |
|
sis->flags |= SWP_FS_OPS; |
|
ret = add_swap_extent(sis, 0, sis->max, 0); |
|
*span = sis->pages; |
|
} |
|
return ret; |
|
} |
|
|
|
return generic_swapfile_activate(sis, swap_file, span); |
|
} |
|
|
|
static int swap_node(struct swap_info_struct *p) |
|
{ |
|
struct block_device *bdev; |
|
|
|
if (p->bdev) |
|
bdev = p->bdev; |
|
else |
|
bdev = p->swap_file->f_inode->i_sb->s_bdev; |
|
|
|
return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; |
|
} |
|
|
|
static void setup_swap_info(struct swap_info_struct *p, int prio, |
|
unsigned char *swap_map, |
|
struct swap_cluster_info *cluster_info) |
|
{ |
|
int i; |
|
|
|
if (prio >= 0) |
|
p->prio = prio; |
|
else |
|
p->prio = --least_priority; |
|
/* |
|
* the plist prio is negated because plist ordering is |
|
* low-to-high, while swap ordering is high-to-low |
|
*/ |
|
p->list.prio = -p->prio; |
|
for_each_node(i) { |
|
if (p->prio >= 0) |
|
p->avail_lists[i].prio = -p->prio; |
|
else { |
|
if (swap_node(p) == i) |
|
p->avail_lists[i].prio = 1; |
|
else |
|
p->avail_lists[i].prio = -p->prio; |
|
} |
|
} |
|
p->swap_map = swap_map; |
|
p->cluster_info = cluster_info; |
|
} |
|
|
|
static void _enable_swap_info(struct swap_info_struct *p) |
|
{ |
|
p->flags |= SWP_WRITEOK; |
|
atomic_long_add(p->pages, &nr_swap_pages); |
|
total_swap_pages += p->pages; |
|
|
|
assert_spin_locked(&swap_lock); |
|
/* |
|
* both lists are plists, and thus priority ordered. |
|
* swap_active_head needs to be priority ordered for swapoff(), |
|
* which on removal of any swap_info_struct with an auto-assigned |
|
* (i.e. negative) priority increments the auto-assigned priority |
|
* of any lower-priority swap_info_structs. |
|
* swap_avail_head needs to be priority ordered for get_swap_page(), |
|
* which allocates swap pages from the highest available priority |
|
* swap_info_struct. |
|
*/ |
|
plist_add(&p->list, &swap_active_head); |
|
add_to_avail_list(p); |
|
} |
|
|
|
static void enable_swap_info(struct swap_info_struct *p, int prio, |
|
unsigned char *swap_map, |
|
struct swap_cluster_info *cluster_info, |
|
unsigned long *frontswap_map) |
|
{ |
|
frontswap_init(p->type, frontswap_map); |
|
spin_lock(&swap_lock); |
|
spin_lock(&p->lock); |
|
setup_swap_info(p, prio, swap_map, cluster_info); |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
/* |
|
* Finished initializing swap device, now it's safe to reference it. |
|
*/ |
|
percpu_ref_resurrect(&p->users); |
|
spin_lock(&swap_lock); |
|
spin_lock(&p->lock); |
|
_enable_swap_info(p); |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
} |
|
|
|
static void reinsert_swap_info(struct swap_info_struct *p) |
|
{ |
|
spin_lock(&swap_lock); |
|
spin_lock(&p->lock); |
|
setup_swap_info(p, p->prio, p->swap_map, p->cluster_info); |
|
_enable_swap_info(p); |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
} |
|
|
|
bool has_usable_swap(void) |
|
{ |
|
bool ret = true; |
|
|
|
spin_lock(&swap_lock); |
|
if (plist_head_empty(&swap_active_head)) |
|
ret = false; |
|
spin_unlock(&swap_lock); |
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
|
{ |
|
struct swap_info_struct *p = NULL; |
|
unsigned char *swap_map; |
|
struct swap_cluster_info *cluster_info; |
|
unsigned long *frontswap_map; |
|
struct file *swap_file, *victim; |
|
struct address_space *mapping; |
|
struct inode *inode; |
|
struct filename *pathname; |
|
int err, found = 0; |
|
unsigned int old_block_size; |
|
|
|
if (!capable(CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
|
|
BUG_ON(!current->mm); |
|
|
|
pathname = getname(specialfile); |
|
if (IS_ERR(pathname)) |
|
return PTR_ERR(pathname); |
|
|
|
victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
|
err = PTR_ERR(victim); |
|
if (IS_ERR(victim)) |
|
goto out; |
|
|
|
mapping = victim->f_mapping; |
|
spin_lock(&swap_lock); |
|
plist_for_each_entry(p, &swap_active_head, list) { |
|
if (p->flags & SWP_WRITEOK) { |
|
if (p->swap_file->f_mapping == mapping) { |
|
found = 1; |
|
break; |
|
} |
|
} |
|
} |
|
if (!found) { |
|
err = -EINVAL; |
|
spin_unlock(&swap_lock); |
|
goto out_dput; |
|
} |
|
if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
|
vm_unacct_memory(p->pages); |
|
else { |
|
err = -ENOMEM; |
|
spin_unlock(&swap_lock); |
|
goto out_dput; |
|
} |
|
del_from_avail_list(p); |
|
spin_lock(&p->lock); |
|
if (p->prio < 0) { |
|
struct swap_info_struct *si = p; |
|
int nid; |
|
|
|
plist_for_each_entry_continue(si, &swap_active_head, list) { |
|
si->prio++; |
|
si->list.prio--; |
|
for_each_node(nid) { |
|
if (si->avail_lists[nid].prio != 1) |
|
si->avail_lists[nid].prio--; |
|
} |
|
} |
|
least_priority++; |
|
} |
|
plist_del(&p->list, &swap_active_head); |
|
atomic_long_sub(p->pages, &nr_swap_pages); |
|
total_swap_pages -= p->pages; |
|
p->flags &= ~SWP_WRITEOK; |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
|
|
disable_swap_slots_cache_lock(); |
|
|
|
set_current_oom_origin(); |
|
err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ |
|
clear_current_oom_origin(); |
|
|
|
if (err) { |
|
/* re-insert swap space back into swap_list */ |
|
reinsert_swap_info(p); |
|
reenable_swap_slots_cache_unlock(); |
|
goto out_dput; |
|
} |
|
|
|
reenable_swap_slots_cache_unlock(); |
|
|
|
/* |
|
* Wait for swap operations protected by get/put_swap_device() |
|
* to complete. |
|
* |
|
* We need synchronize_rcu() here to protect the accessing to |
|
* the swap cache data structure. |
|
*/ |
|
percpu_ref_kill(&p->users); |
|
synchronize_rcu(); |
|
wait_for_completion(&p->comp); |
|
|
|
flush_work(&p->discard_work); |
|
|
|
destroy_swap_extents(p); |
|
if (p->flags & SWP_CONTINUED) |
|
free_swap_count_continuations(p); |
|
|
|
if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev))) |
|
atomic_dec(&nr_rotate_swap); |
|
|
|
mutex_lock(&swapon_mutex); |
|
spin_lock(&swap_lock); |
|
spin_lock(&p->lock); |
|
drain_mmlist(); |
|
|
|
/* wait for anyone still in scan_swap_map_slots */ |
|
p->highest_bit = 0; /* cuts scans short */ |
|
while (p->flags >= SWP_SCANNING) { |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
schedule_timeout_uninterruptible(1); |
|
spin_lock(&swap_lock); |
|
spin_lock(&p->lock); |
|
} |
|
|
|
swap_file = p->swap_file; |
|
old_block_size = p->old_block_size; |
|
p->swap_file = NULL; |
|
p->max = 0; |
|
swap_map = p->swap_map; |
|
p->swap_map = NULL; |
|
cluster_info = p->cluster_info; |
|
p->cluster_info = NULL; |
|
frontswap_map = frontswap_map_get(p); |
|
spin_unlock(&p->lock); |
|
spin_unlock(&swap_lock); |
|
arch_swap_invalidate_area(p->type); |
|
frontswap_invalidate_area(p->type); |
|
frontswap_map_set(p, NULL); |
|
mutex_unlock(&swapon_mutex); |
|
free_percpu(p->percpu_cluster); |
|
p->percpu_cluster = NULL; |
|
free_percpu(p->cluster_next_cpu); |
|
p->cluster_next_cpu = NULL; |
|
vfree(swap_map); |
|
kvfree(cluster_info); |
|
kvfree(frontswap_map); |
|
/* Destroy swap account information */ |
|
swap_cgroup_swapoff(p->type); |
|
exit_swap_address_space(p->type); |
|
|
|
inode = mapping->host; |
|
if (S_ISBLK(inode->i_mode)) { |
|
struct block_device *bdev = I_BDEV(inode); |
|
|
|
set_blocksize(bdev, old_block_size); |
|
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
|
} |
|
|
|
inode_lock(inode); |
|
inode->i_flags &= ~S_SWAPFILE; |
|
inode_unlock(inode); |
|
filp_close(swap_file, NULL); |
|
|
|
/* |
|
* Clear the SWP_USED flag after all resources are freed so that swapon |
|
* can reuse this swap_info in alloc_swap_info() safely. It is ok to |
|
* not hold p->lock after we cleared its SWP_WRITEOK. |
|
*/ |
|
spin_lock(&swap_lock); |
|
p->flags = 0; |
|
spin_unlock(&swap_lock); |
|
|
|
err = 0; |
|
atomic_inc(&proc_poll_event); |
|
wake_up_interruptible(&proc_poll_wait); |
|
|
|
out_dput: |
|
filp_close(victim, NULL); |
|
out: |
|
putname(pathname); |
|
return err; |
|
} |
|
|
|
#ifdef CONFIG_PROC_FS |
|
static __poll_t swaps_poll(struct file *file, poll_table *wait) |
|
{ |
|
struct seq_file *seq = file->private_data; |
|
|
|
poll_wait(file, &proc_poll_wait, wait); |
|
|
|
if (seq->poll_event != atomic_read(&proc_poll_event)) { |
|
seq->poll_event = atomic_read(&proc_poll_event); |
|
return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
|
} |
|
|
|
return EPOLLIN | EPOLLRDNORM; |
|
} |
|
|
|
/* iterator */ |
|
static void *swap_start(struct seq_file *swap, loff_t *pos) |
|
{ |
|
struct swap_info_struct *si; |
|
int type; |
|
loff_t l = *pos; |
|
|
|
mutex_lock(&swapon_mutex); |
|
|
|
if (!l) |
|
return SEQ_START_TOKEN; |
|
|
|
for (type = 0; (si = swap_type_to_swap_info(type)); type++) { |
|
if (!(si->flags & SWP_USED) || !si->swap_map) |
|
continue; |
|
if (!--l) |
|
return si; |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
|
{ |
|
struct swap_info_struct *si = v; |
|
int type; |
|
|
|
if (v == SEQ_START_TOKEN) |
|
type = 0; |
|
else |
|
type = si->type + 1; |
|
|
|
++(*pos); |
|
for (; (si = swap_type_to_swap_info(type)); type++) { |
|
if (!(si->flags & SWP_USED) || !si->swap_map) |
|
continue; |
|
return si; |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
static void swap_stop(struct seq_file *swap, void *v) |
|
{ |
|
mutex_unlock(&swapon_mutex); |
|
} |
|
|
|
static int swap_show(struct seq_file *swap, void *v) |
|
{ |
|
struct swap_info_struct *si = v; |
|
struct file *file; |
|
int len; |
|
unsigned int bytes, inuse; |
|
|
|
if (si == SEQ_START_TOKEN) { |
|
seq_puts(swap, "Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n"); |
|
return 0; |
|
} |
|
|
|
bytes = si->pages << (PAGE_SHIFT - 10); |
|
inuse = si->inuse_pages << (PAGE_SHIFT - 10); |
|
|
|
file = si->swap_file; |
|
len = seq_file_path(swap, file, " \t\n\\"); |
|
seq_printf(swap, "%*s%s\t%u\t%s%u\t%s%d\n", |
|
len < 40 ? 40 - len : 1, " ", |
|
S_ISBLK(file_inode(file)->i_mode) ? |
|
"partition" : "file\t", |
|
bytes, bytes < 10000000 ? "\t" : "", |
|
inuse, inuse < 10000000 ? "\t" : "", |
|
si->prio); |
|
return 0; |
|
} |
|
|
|
static const struct seq_operations swaps_op = { |
|
.start = swap_start, |
|
.next = swap_next, |
|
.stop = swap_stop, |
|
.show = swap_show |
|
}; |
|
|
|
static int swaps_open(struct inode *inode, struct file *file) |
|
{ |
|
struct seq_file *seq; |
|
int ret; |
|
|
|
ret = seq_open(file, &swaps_op); |
|
if (ret) |
|
return ret; |
|
|
|
seq = file->private_data; |
|
seq->poll_event = atomic_read(&proc_poll_event); |
|
return 0; |
|
} |
|
|
|
static const struct proc_ops swaps_proc_ops = { |
|
.proc_flags = PROC_ENTRY_PERMANENT, |
|
.proc_open = swaps_open, |
|
.proc_read = seq_read, |
|
.proc_lseek = seq_lseek, |
|
.proc_release = seq_release, |
|
.proc_poll = swaps_poll, |
|
}; |
|
|
|
static int __init procswaps_init(void) |
|
{ |
|
proc_create("swaps", 0, NULL, &swaps_proc_ops); |
|
return 0; |
|
} |
|
__initcall(procswaps_init); |
|
#endif /* CONFIG_PROC_FS */ |
|
|
|
#ifdef MAX_SWAPFILES_CHECK |
|
static int __init max_swapfiles_check(void) |
|
{ |
|
MAX_SWAPFILES_CHECK(); |
|
return 0; |
|
} |
|
late_initcall(max_swapfiles_check); |
|
#endif |
|
|
|
static struct swap_info_struct *alloc_swap_info(void) |
|
{ |
|
struct swap_info_struct *p; |
|
struct swap_info_struct *defer = NULL; |
|
unsigned int type; |
|
int i; |
|
|
|
p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); |
|
if (!p) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
if (percpu_ref_init(&p->users, swap_users_ref_free, |
|
PERCPU_REF_INIT_DEAD, GFP_KERNEL)) { |
|
kvfree(p); |
|
return ERR_PTR(-ENOMEM); |
|
} |
|
|
|
spin_lock(&swap_lock); |
|
for (type = 0; type < nr_swapfiles; type++) { |
|
if (!(swap_info[type]->flags & SWP_USED)) |
|
break; |
|
} |
|
if (type >= MAX_SWAPFILES) { |
|
spin_unlock(&swap_lock); |
|
percpu_ref_exit(&p->users); |
|
kvfree(p); |
|
return ERR_PTR(-EPERM); |
|
} |
|
if (type >= nr_swapfiles) { |
|
p->type = type; |
|
/* |
|
* Publish the swap_info_struct after initializing it. |
|
* Note that kvzalloc() above zeroes all its fields. |
|
*/ |
|
smp_store_release(&swap_info[type], p); /* rcu_assign_pointer() */ |
|
nr_swapfiles++; |
|
} else { |
|
defer = p; |
|
p = swap_info[type]; |
|
/* |
|
* Do not memset this entry: a racing procfs swap_next() |
|
* would be relying on p->type to remain valid. |
|
*/ |
|
} |
|
p->swap_extent_root = RB_ROOT; |
|
plist_node_init(&p->list, 0); |
|
for_each_node(i) |
|
plist_node_init(&p->avail_lists[i], 0); |
|
p->flags = SWP_USED; |
|
spin_unlock(&swap_lock); |
|
if (defer) { |
|
percpu_ref_exit(&defer->users); |
|
kvfree(defer); |
|
} |
|
spin_lock_init(&p->lock); |
|
spin_lock_init(&p->cont_lock); |
|
init_completion(&p->comp); |
|
|
|
return p; |
|
} |
|
|
|
static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
|
{ |
|
int error; |
|
|
|
if (S_ISBLK(inode->i_mode)) { |
|
p->bdev = blkdev_get_by_dev(inode->i_rdev, |
|
FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); |
|
if (IS_ERR(p->bdev)) { |
|
error = PTR_ERR(p->bdev); |
|
p->bdev = NULL; |
|
return error; |
|
} |
|
p->old_block_size = block_size(p->bdev); |
|
error = set_blocksize(p->bdev, PAGE_SIZE); |
|
if (error < 0) |
|
return error; |
|
/* |
|
* Zoned block devices contain zones that have a sequential |
|
* write only restriction. Hence zoned block devices are not |
|
* suitable for swapping. Disallow them here. |
|
*/ |
|
if (blk_queue_is_zoned(p->bdev->bd_disk->queue)) |
|
return -EINVAL; |
|
p->flags |= SWP_BLKDEV; |
|
} else if (S_ISREG(inode->i_mode)) { |
|
p->bdev = inode->i_sb->s_bdev; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
|
|
/* |
|
* Find out how many pages are allowed for a single swap device. There |
|
* are two limiting factors: |
|
* 1) the number of bits for the swap offset in the swp_entry_t type, and |
|
* 2) the number of bits in the swap pte, as defined by the different |
|
* architectures. |
|
* |
|
* In order to find the largest possible bit mask, a swap entry with |
|
* swap type 0 and swap offset ~0UL is created, encoded to a swap pte, |
|
* decoded to a swp_entry_t again, and finally the swap offset is |
|
* extracted. |
|
* |
|
* This will mask all the bits from the initial ~0UL mask that can't |
|
* be encoded in either the swp_entry_t or the architecture definition |
|
* of a swap pte. |
|
*/ |
|
unsigned long generic_max_swapfile_size(void) |
|
{ |
|
return swp_offset(pte_to_swp_entry( |
|
swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
|
} |
|
|
|
/* Can be overridden by an architecture for additional checks. */ |
|
__weak unsigned long max_swapfile_size(void) |
|
{ |
|
return generic_max_swapfile_size(); |
|
} |
|
|
|
static unsigned long read_swap_header(struct swap_info_struct *p, |
|
union swap_header *swap_header, |
|
struct inode *inode) |
|
{ |
|
int i; |
|
unsigned long maxpages; |
|
unsigned long swapfilepages; |
|
unsigned long last_page; |
|
|
|
if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
|
pr_err("Unable to find swap-space signature\n"); |
|
return 0; |
|
} |
|
|
|
/* swap partition endianness hack... */ |
|
if (swab32(swap_header->info.version) == 1) { |
|
swab32s(&swap_header->info.version); |
|
swab32s(&swap_header->info.last_page); |
|
swab32s(&swap_header->info.nr_badpages); |
|
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
|
return 0; |
|
for (i = 0; i < swap_header->info.nr_badpages; i++) |
|
swab32s(&swap_header->info.badpages[i]); |
|
} |
|
/* Check the swap header's sub-version */ |
|
if (swap_header->info.version != 1) { |
|
pr_warn("Unable to handle swap header version %d\n", |
|
swap_header->info.version); |
|
return 0; |
|
} |
|
|
|
p->lowest_bit = 1; |
|
p->cluster_next = 1; |
|
p->cluster_nr = 0; |
|
|
|
maxpages = max_swapfile_size(); |
|
last_page = swap_header->info.last_page; |
|
if (!last_page) { |
|
pr_warn("Empty swap-file\n"); |
|
return 0; |
|
} |
|
if (last_page > maxpages) { |
|
pr_warn("Truncating oversized swap area, only using %luk out of %luk\n", |
|
maxpages << (PAGE_SHIFT - 10), |
|
last_page << (PAGE_SHIFT - 10)); |
|
} |
|
if (maxpages > last_page) { |
|
maxpages = last_page + 1; |
|
/* p->max is an unsigned int: don't overflow it */ |
|
if ((unsigned int)maxpages == 0) |
|
maxpages = UINT_MAX; |
|
} |
|
p->highest_bit = maxpages - 1; |
|
|
|
if (!maxpages) |
|
return 0; |
|
swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
|
if (swapfilepages && maxpages > swapfilepages) { |
|
pr_warn("Swap area shorter than signature indicates\n"); |
|
return 0; |
|
} |
|
if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
|
return 0; |
|
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
|
return 0; |
|
|
|
return maxpages; |
|
} |
|
|
|
#define SWAP_CLUSTER_INFO_COLS \ |
|
DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) |
|
#define SWAP_CLUSTER_SPACE_COLS \ |
|
DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) |
|
#define SWAP_CLUSTER_COLS \ |
|
max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) |
|
|
|
static int setup_swap_map_and_extents(struct swap_info_struct *p, |
|
union swap_header *swap_header, |
|
unsigned char *swap_map, |
|
struct swap_cluster_info *cluster_info, |
|
unsigned long maxpages, |
|
sector_t *span) |
|
{ |
|
unsigned int j, k; |
|
unsigned int nr_good_pages; |
|
int nr_extents; |
|
unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
|
unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; |
|
unsigned long i, idx; |
|
|
|
nr_good_pages = maxpages - 1; /* omit header page */ |
|
|
|
cluster_list_init(&p->free_clusters); |
|
cluster_list_init(&p->discard_clusters); |
|
|
|
for (i = 0; i < swap_header->info.nr_badpages; i++) { |
|
unsigned int page_nr = swap_header->info.badpages[i]; |
|
if (page_nr == 0 || page_nr > swap_header->info.last_page) |
|
return -EINVAL; |
|
if (page_nr < maxpages) { |
|
swap_map[page_nr] = SWAP_MAP_BAD; |
|
nr_good_pages--; |
|
/* |
|
* Haven't marked the cluster free yet, no list |
|
* operation involved |
|
*/ |
|
inc_cluster_info_page(p, cluster_info, page_nr); |
|
} |
|
} |
|
|
|
/* Haven't marked the cluster free yet, no list operation involved */ |
|
for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) |
|
inc_cluster_info_page(p, cluster_info, i); |
|
|
|
if (nr_good_pages) { |
|
swap_map[0] = SWAP_MAP_BAD; |
|
/* |
|
* Not mark the cluster free yet, no list |
|
* operation involved |
|
*/ |
|
inc_cluster_info_page(p, cluster_info, 0); |
|
p->max = maxpages; |
|
p->pages = nr_good_pages; |
|
nr_extents = setup_swap_extents(p, span); |
|
if (nr_extents < 0) |
|
return nr_extents; |
|
nr_good_pages = p->pages; |
|
} |
|
if (!nr_good_pages) { |
|
pr_warn("Empty swap-file\n"); |
|
return -EINVAL; |
|
} |
|
|
|
if (!cluster_info) |
|
return nr_extents; |
|
|
|
|
|
/* |
|
* Reduce false cache line sharing between cluster_info and |
|
* sharing same address space. |
|
*/ |
|
for (k = 0; k < SWAP_CLUSTER_COLS; k++) { |
|
j = (k + col) % SWAP_CLUSTER_COLS; |
|
for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { |
|
idx = i * SWAP_CLUSTER_COLS + j; |
|
if (idx >= nr_clusters) |
|
continue; |
|
if (cluster_count(&cluster_info[idx])) |
|
continue; |
|
cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); |
|
cluster_list_add_tail(&p->free_clusters, cluster_info, |
|
idx); |
|
} |
|
} |
|
return nr_extents; |
|
} |
|
|
|
/* |
|
* Helper to sys_swapon determining if a given swap |
|
* backing device queue supports DISCARD operations. |
|
*/ |
|
static bool swap_discardable(struct swap_info_struct *si) |
|
{ |
|
struct request_queue *q = bdev_get_queue(si->bdev); |
|
|
|
if (!q || !blk_queue_discard(q)) |
|
return false; |
|
|
|
return true; |
|
} |
|
|
|
SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) |
|
{ |
|
struct swap_info_struct *p; |
|
struct filename *name; |
|
struct file *swap_file = NULL; |
|
struct address_space *mapping; |
|
struct dentry *dentry; |
|
int prio; |
|
int error; |
|
union swap_header *swap_header; |
|
int nr_extents; |
|
sector_t span; |
|
unsigned long maxpages; |
|
unsigned char *swap_map = NULL; |
|
struct swap_cluster_info *cluster_info = NULL; |
|
unsigned long *frontswap_map = NULL; |
|
struct page *page = NULL; |
|
struct inode *inode = NULL; |
|
bool inced_nr_rotate_swap = false; |
|
|
|
if (swap_flags & ~SWAP_FLAGS_VALID) |
|
return -EINVAL; |
|
|
|
if (!capable(CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
|
|
if (!swap_avail_heads) |
|
return -ENOMEM; |
|
|
|
p = alloc_swap_info(); |
|
if (IS_ERR(p)) |
|
return PTR_ERR(p); |
|
|
|
INIT_WORK(&p->discard_work, swap_discard_work); |
|
|
|
name = getname(specialfile); |
|
if (IS_ERR(name)) { |
|
error = PTR_ERR(name); |
|
name = NULL; |
|
goto bad_swap; |
|
} |
|
swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); |
|
if (IS_ERR(swap_file)) { |
|
error = PTR_ERR(swap_file); |
|
swap_file = NULL; |
|
goto bad_swap; |
|
} |
|
|
|
p->swap_file = swap_file; |
|
mapping = swap_file->f_mapping; |
|
dentry = swap_file->f_path.dentry; |
|
inode = mapping->host; |
|
|
|
error = claim_swapfile(p, inode); |
|
if (unlikely(error)) |
|
goto bad_swap; |
|
|
|
inode_lock(inode); |
|
if (d_unlinked(dentry) || cant_mount(dentry)) { |
|
error = -ENOENT; |
|
goto bad_swap_unlock_inode; |
|
} |
|
if (IS_SWAPFILE(inode)) { |
|
error = -EBUSY; |
|
goto bad_swap_unlock_inode; |
|
} |
|
|
|
/* |
|
* Read the swap header. |
|
*/ |
|
if (!mapping->a_ops->readpage) { |
|
error = -EINVAL; |
|
goto bad_swap_unlock_inode; |
|
} |
|
page = read_mapping_page(mapping, 0, swap_file); |
|
if (IS_ERR(page)) { |
|
error = PTR_ERR(page); |
|
goto bad_swap_unlock_inode; |
|
} |
|
swap_header = kmap(page); |
|
|
|
maxpages = read_swap_header(p, swap_header, inode); |
|
if (unlikely(!maxpages)) { |
|
error = -EINVAL; |
|
goto bad_swap_unlock_inode; |
|
} |
|
|
|
/* OK, set up the swap map and apply the bad block list */ |
|
swap_map = vzalloc(maxpages); |
|
if (!swap_map) { |
|
error = -ENOMEM; |
|
goto bad_swap_unlock_inode; |
|
} |
|
|
|
if (p->bdev && blk_queue_stable_writes(p->bdev->bd_disk->queue)) |
|
p->flags |= SWP_STABLE_WRITES; |
|
|
|
if (p->bdev && p->bdev->bd_disk->fops->rw_page) |
|
p->flags |= SWP_SYNCHRONOUS_IO; |
|
|
|
if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { |
|
int cpu; |
|
unsigned long ci, nr_cluster; |
|
|
|
p->flags |= SWP_SOLIDSTATE; |
|
p->cluster_next_cpu = alloc_percpu(unsigned int); |
|
if (!p->cluster_next_cpu) { |
|
error = -ENOMEM; |
|
goto bad_swap_unlock_inode; |
|
} |
|
/* |
|
* select a random position to start with to help wear leveling |
|
* SSD |
|
*/ |
|
for_each_possible_cpu(cpu) { |
|
per_cpu(*p->cluster_next_cpu, cpu) = |
|
1 + prandom_u32_max(p->highest_bit); |
|
} |
|
nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
|
|
|
cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info), |
|
GFP_KERNEL); |
|
if (!cluster_info) { |
|
error = -ENOMEM; |
|
goto bad_swap_unlock_inode; |
|
} |
|
|
|
for (ci = 0; ci < nr_cluster; ci++) |
|
spin_lock_init(&((cluster_info + ci)->lock)); |
|
|
|
p->percpu_cluster = alloc_percpu(struct percpu_cluster); |
|
if (!p->percpu_cluster) { |
|
error = -ENOMEM; |
|
goto bad_swap_unlock_inode; |
|
} |
|
for_each_possible_cpu(cpu) { |
|
struct percpu_cluster *cluster; |
|
cluster = per_cpu_ptr(p->percpu_cluster, cpu); |
|
cluster_set_null(&cluster->index); |
|
} |
|
} else { |
|
atomic_inc(&nr_rotate_swap); |
|
inced_nr_rotate_swap = true; |
|
} |
|
|
|
error = swap_cgroup_swapon(p->type, maxpages); |
|
if (error) |
|
goto bad_swap_unlock_inode; |
|
|
|
nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map, |
|
cluster_info, maxpages, &span); |
|
if (unlikely(nr_extents < 0)) { |
|
error = nr_extents; |
|
goto bad_swap_unlock_inode; |
|
} |
|
/* frontswap enabled? set up bit-per-page map for frontswap */ |
|
if (IS_ENABLED(CONFIG_FRONTSWAP)) |
|
frontswap_map = kvcalloc(BITS_TO_LONGS(maxpages), |
|
sizeof(long), |
|
GFP_KERNEL); |
|
|
|
if (p->bdev && (swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { |
|
/* |
|
* When discard is enabled for swap with no particular |
|
* policy flagged, we set all swap discard flags here in |
|
* order to sustain backward compatibility with older |
|
* swapon(8) releases. |
|
*/ |
|
p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | |
|
SWP_PAGE_DISCARD); |
|
|
|
/* |
|
* By flagging sys_swapon, a sysadmin can tell us to |
|
* either do single-time area discards only, or to just |
|
* perform discards for released swap page-clusters. |
|
* Now it's time to adjust the p->flags accordingly. |
|
*/ |
|
if (swap_flags & SWAP_FLAG_DISCARD_ONCE) |
|
p->flags &= ~SWP_PAGE_DISCARD; |
|
else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) |
|
p->flags &= ~SWP_AREA_DISCARD; |
|
|
|
/* issue a swapon-time discard if it's still required */ |
|
if (p->flags & SWP_AREA_DISCARD) { |
|
int err = discard_swap(p); |
|
if (unlikely(err)) |
|
pr_err("swapon: discard_swap(%p): %d\n", |
|
p, err); |
|
} |
|
} |
|
|
|
error = init_swap_address_space(p->type, maxpages); |
|
if (error) |
|
goto bad_swap_unlock_inode; |
|
|
|
/* |
|
* Flush any pending IO and dirty mappings before we start using this |
|
* swap device. |
|
*/ |
|
inode->i_flags |= S_SWAPFILE; |
|
error = inode_drain_writes(inode); |
|
if (error) { |
|
inode->i_flags &= ~S_SWAPFILE; |
|
goto free_swap_address_space; |
|
} |
|
|
|
mutex_lock(&swapon_mutex); |
|
prio = -1; |
|
if (swap_flags & SWAP_FLAG_PREFER) |
|
prio = |
|
(swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; |
|
enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); |
|
|
|
pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n", |
|
p->pages<<(PAGE_SHIFT-10), name->name, p->prio, |
|
nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), |
|
(p->flags & SWP_SOLIDSTATE) ? "SS" : "", |
|
(p->flags & SWP_DISCARDABLE) ? "D" : "", |
|
(p->flags & SWP_AREA_DISCARD) ? "s" : "", |
|
(p->flags & SWP_PAGE_DISCARD) ? "c" : "", |
|
(frontswap_map) ? "FS" : ""); |
|
|
|
mutex_unlock(&swapon_mutex); |
|
atomic_inc(&proc_poll_event); |
|
wake_up_interruptible(&proc_poll_wait); |
|
|
|
error = 0; |
|
goto out; |
|
free_swap_address_space: |
|
exit_swap_address_space(p->type); |
|
bad_swap_unlock_inode: |
|
inode_unlock(inode); |
|
bad_swap: |
|
free_percpu(p->percpu_cluster); |
|
p->percpu_cluster = NULL; |
|
free_percpu(p->cluster_next_cpu); |
|
p->cluster_next_cpu = NULL; |
|
if (inode && S_ISBLK(inode->i_mode) && p->bdev) { |
|
set_blocksize(p->bdev, p->old_block_size); |
|
blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
|
} |
|
inode = NULL; |
|
destroy_swap_extents(p); |
|
swap_cgroup_swapoff(p->type); |
|
spin_lock(&swap_lock); |
|
p->swap_file = NULL; |
|
p->flags = 0; |
|
spin_unlock(&swap_lock); |
|
vfree(swap_map); |
|
kvfree(cluster_info); |
|
kvfree(frontswap_map); |
|
if (inced_nr_rotate_swap) |
|
atomic_dec(&nr_rotate_swap); |
|
if (swap_file) |
|
filp_close(swap_file, NULL); |
|
out: |
|
if (page && !IS_ERR(page)) { |
|
kunmap(page); |
|
put_page(page); |
|
} |
|
if (name) |
|
putname(name); |
|
if (inode) |
|
inode_unlock(inode); |
|
if (!error) |
|
enable_swap_slots_cache(); |
|
return error; |
|
} |
|
|
|
void si_swapinfo(struct sysinfo *val) |
|
{ |
|
unsigned int type; |
|
unsigned long nr_to_be_unused = 0; |
|
|
|
spin_lock(&swap_lock); |
|
for (type = 0; type < nr_swapfiles; type++) { |
|
struct swap_info_struct *si = swap_info[type]; |
|
|
|
if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK)) |
|
nr_to_be_unused += si->inuse_pages; |
|
} |
|
val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; |
|
val->totalswap = total_swap_pages + nr_to_be_unused; |
|
spin_unlock(&swap_lock); |
|
} |
|
|
|
/* |
|
* Verify that a swap entry is valid and increment its swap map count. |
|
* |
|
* Returns error code in following case. |
|
* - success -> 0 |
|
* - swp_entry is invalid -> EINVAL |
|
* - swp_entry is migration entry -> EINVAL |
|
* - swap-cache reference is requested but there is already one. -> EEXIST |
|
* - swap-cache reference is requested but the entry is not used. -> ENOENT |
|
* - swap-mapped reference requested but needs continued swap count. -> ENOMEM |
|
*/ |
|
static int __swap_duplicate(swp_entry_t entry, unsigned char usage) |
|
{ |
|
struct swap_info_struct *p; |
|
struct swap_cluster_info *ci; |
|
unsigned long offset; |
|
unsigned char count; |
|
unsigned char has_cache; |
|
int err; |
|
|
|
p = get_swap_device(entry); |
|
if (!p) |
|
return -EINVAL; |
|
|
|
offset = swp_offset(entry); |
|
ci = lock_cluster_or_swap_info(p, offset); |
|
|
|
count = p->swap_map[offset]; |
|
|
|
/* |
|
* swapin_readahead() doesn't check if a swap entry is valid, so the |
|
* swap entry could be SWAP_MAP_BAD. Check here with lock held. |
|
*/ |
|
if (unlikely(swap_count(count) == SWAP_MAP_BAD)) { |
|
err = -ENOENT; |
|
goto unlock_out; |
|
} |
|
|
|
has_cache = count & SWAP_HAS_CACHE; |
|
count &= ~SWAP_HAS_CACHE; |
|
err = 0; |
|
|
|
if (usage == SWAP_HAS_CACHE) { |
|
|
|
/* set SWAP_HAS_CACHE if there is no cache and entry is used */ |
|
if (!has_cache && count) |
|
has_cache = SWAP_HAS_CACHE; |
|
else if (has_cache) /* someone else added cache */ |
|
err = -EEXIST; |
|
else /* no users remaining */ |
|
err = -ENOENT; |
|
|
|
} else if (count || has_cache) { |
|
|
|
if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) |
|
count += usage; |
|
else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) |
|
err = -EINVAL; |
|
else if (swap_count_continued(p, offset, count)) |
|
count = COUNT_CONTINUED; |
|
else |
|
err = -ENOMEM; |
|
} else |
|
err = -ENOENT; /* unused swap entry */ |
|
|
|
WRITE_ONCE(p->swap_map[offset], count | has_cache); |
|
|
|
unlock_out: |
|
unlock_cluster_or_swap_info(p, ci); |
|
if (p) |
|
put_swap_device(p); |
|
return err; |
|
} |
|
|
|
/* |
|
* Help swapoff by noting that swap entry belongs to shmem/tmpfs |
|
* (in which case its reference count is never incremented). |
|
*/ |
|
void swap_shmem_alloc(swp_entry_t entry) |
|
{ |
|
__swap_duplicate(entry, SWAP_MAP_SHMEM); |
|
} |
|
|
|
/* |
|
* Increase reference count of swap entry by 1. |
|
* Returns 0 for success, or -ENOMEM if a swap_count_continuation is required |
|
* but could not be atomically allocated. Returns 0, just as if it succeeded, |
|
* if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which |
|
* might occur if a page table entry has got corrupted. |
|
*/ |
|
int swap_duplicate(swp_entry_t entry) |
|
{ |
|
int err = 0; |
|
|
|
while (!err && __swap_duplicate(entry, 1) == -ENOMEM) |
|
err = add_swap_count_continuation(entry, GFP_ATOMIC); |
|
return err; |
|
} |
|
|
|
/* |
|
* @entry: swap entry for which we allocate swap cache. |
|
* |
|
* Called when allocating swap cache for existing swap entry, |
|
* This can return error codes. Returns 0 at success. |
|
* -EEXIST means there is a swap cache. |
|
* Note: return code is different from swap_duplicate(). |
|
*/ |
|
int swapcache_prepare(swp_entry_t entry) |
|
{ |
|
return __swap_duplicate(entry, SWAP_HAS_CACHE); |
|
} |
|
|
|
struct swap_info_struct *swp_swap_info(swp_entry_t entry) |
|
{ |
|
return swap_type_to_swap_info(swp_type(entry)); |
|
} |
|
|
|
struct swap_info_struct *page_swap_info(struct page *page) |
|
{ |
|
swp_entry_t entry = { .val = page_private(page) }; |
|
return swp_swap_info(entry); |
|
} |
|
|
|
/* |
|
* out-of-line __page_file_ methods to avoid include hell. |
|
*/ |
|
struct address_space *__page_file_mapping(struct page *page) |
|
{ |
|
return page_swap_info(page)->swap_file->f_mapping; |
|
} |
|
EXPORT_SYMBOL_GPL(__page_file_mapping); |
|
|
|
pgoff_t __page_file_index(struct page *page) |
|
{ |
|
swp_entry_t swap = { .val = page_private(page) }; |
|
return swp_offset(swap); |
|
} |
|
EXPORT_SYMBOL_GPL(__page_file_index); |
|
|
|
/* |
|
* add_swap_count_continuation - called when a swap count is duplicated |
|
* beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's |
|
* page of the original vmalloc'ed swap_map, to hold the continuation count |
|
* (for that entry and for its neighbouring PAGE_SIZE swap entries). Called |
|
* again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc. |
|
* |
|
* These continuation pages are seldom referenced: the common paths all work |
|
* on the original swap_map, only referring to a continuation page when the |
|
* low "digit" of a count is incremented or decremented through SWAP_MAP_MAX. |
|
* |
|
* add_swap_count_continuation(, GFP_ATOMIC) can be called while holding |
|
* page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL) |
|
* can be called after dropping locks. |
|
*/ |
|
int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) |
|
{ |
|
struct swap_info_struct *si; |
|
struct swap_cluster_info *ci; |
|
struct page *head; |
|
struct page *page; |
|
struct page *list_page; |
|
pgoff_t offset; |
|
unsigned char count; |
|
int ret = 0; |
|
|
|
/* |
|
* When debugging, it's easier to use __GFP_ZERO here; but it's better |
|
* for latency not to zero a page while GFP_ATOMIC and holding locks. |
|
*/ |
|
page = alloc_page(gfp_mask | __GFP_HIGHMEM); |
|
|
|
si = get_swap_device(entry); |
|
if (!si) { |
|
/* |
|
* An acceptable race has occurred since the failing |
|
* __swap_duplicate(): the swap device may be swapoff |
|
*/ |
|
goto outer; |
|
} |
|
spin_lock(&si->lock); |
|
|
|
offset = swp_offset(entry); |
|
|
|
ci = lock_cluster(si, offset); |
|
|
|
count = swap_count(si->swap_map[offset]); |
|
|
|
if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) { |
|
/* |
|
* The higher the swap count, the more likely it is that tasks |
|
* will race to add swap count continuation: we need to avoid |
|
* over-provisioning. |
|
*/ |
|
goto out; |
|
} |
|
|
|
if (!page) { |
|
ret = -ENOMEM; |
|
goto out; |
|
} |
|
|
|
/* |
|
* We are fortunate that although vmalloc_to_page uses pte_offset_map, |
|
* no architecture is using highmem pages for kernel page tables: so it |
|
* will not corrupt the GFP_ATOMIC caller's atomic page table kmaps. |
|
*/ |
|
head = vmalloc_to_page(si->swap_map + offset); |
|
offset &= ~PAGE_MASK; |
|
|
|
spin_lock(&si->cont_lock); |
|
/* |
|
* Page allocation does not initialize the page's lru field, |
|
* but it does always reset its private field. |
|
*/ |
|
if (!page_private(head)) { |
|
BUG_ON(count & COUNT_CONTINUED); |
|
INIT_LIST_HEAD(&head->lru); |
|
set_page_private(head, SWP_CONTINUED); |
|
si->flags |= SWP_CONTINUED; |
|
} |
|
|
|
list_for_each_entry(list_page, &head->lru, lru) { |
|
unsigned char *map; |
|
|
|
/* |
|
* If the previous map said no continuation, but we've found |
|
* a continuation page, free our allocation and use this one. |
|
*/ |
|
if (!(count & COUNT_CONTINUED)) |
|
goto out_unlock_cont; |
|
|
|
map = kmap_atomic(list_page) + offset; |
|
count = *map; |
|
kunmap_atomic(map); |
|
|
|
/* |
|
* If this continuation count now has some space in it, |
|
* free our allocation and use this one. |
|
*/ |
|
if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX) |
|
goto out_unlock_cont; |
|
} |
|
|
|
list_add_tail(&page->lru, &head->lru); |
|
page = NULL; /* now it's attached, don't free it */ |
|
out_unlock_cont: |
|
spin_unlock(&si->cont_lock); |
|
out: |
|
unlock_cluster(ci); |
|
spin_unlock(&si->lock); |
|
put_swap_device(si); |
|
outer: |
|
if (page) |
|
__free_page(page); |
|
return ret; |
|
} |
|
|
|
/* |
|
* swap_count_continued - when the original swap_map count is incremented |
|
* from SWAP_MAP_MAX, check if there is already a continuation page to carry |
|
* into, carry if so, or else fail until a new continuation page is allocated; |
|
* when the original swap_map count is decremented from 0 with continuation, |
|
* borrow from the continuation and report whether it still holds more. |
|
* Called while __swap_duplicate() or swap_entry_free() holds swap or cluster |
|
* lock. |
|
*/ |
|
static bool swap_count_continued(struct swap_info_struct *si, |
|
pgoff_t offset, unsigned char count) |
|
{ |
|
struct page *head; |
|
struct page *page; |
|
unsigned char *map; |
|
bool ret; |
|
|
|
head = vmalloc_to_page(si->swap_map + offset); |
|
if (page_private(head) != SWP_CONTINUED) { |
|
BUG_ON(count & COUNT_CONTINUED); |
|
return false; /* need to add count continuation */ |
|
} |
|
|
|
spin_lock(&si->cont_lock); |
|
offset &= ~PAGE_MASK; |
|
page = list_next_entry(head, lru); |
|
map = kmap_atomic(page) + offset; |
|
|
|
if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ |
|
goto init_map; /* jump over SWAP_CONT_MAX checks */ |
|
|
|
if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */ |
|
/* |
|
* Think of how you add 1 to 999 |
|
*/ |
|
while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { |
|
kunmap_atomic(map); |
|
page = list_next_entry(page, lru); |
|
BUG_ON(page == head); |
|
map = kmap_atomic(page) + offset; |
|
} |
|
if (*map == SWAP_CONT_MAX) { |
|
kunmap_atomic(map); |
|
page = list_next_entry(page, lru); |
|
if (page == head) { |
|
ret = false; /* add count continuation */ |
|
goto out; |
|
} |
|
map = kmap_atomic(page) + offset; |
|
init_map: *map = 0; /* we didn't zero the page */ |
|
} |
|
*map += 1; |
|
kunmap_atomic(map); |
|
while ((page = list_prev_entry(page, lru)) != head) { |
|
map = kmap_atomic(page) + offset; |
|
*map = COUNT_CONTINUED; |
|
kunmap_atomic(map); |
|
} |
|
ret = true; /* incremented */ |
|
|
|
} else { /* decrementing */ |
|
/* |
|
* Think of how you subtract 1 from 1000 |
|
*/ |
|
BUG_ON(count != COUNT_CONTINUED); |
|
while (*map == COUNT_CONTINUED) { |
|
kunmap_atomic(map); |
|
page = list_next_entry(page, lru); |
|
BUG_ON(page == head); |
|
map = kmap_atomic(page) + offset; |
|
} |
|
BUG_ON(*map == 0); |
|
*map -= 1; |
|
if (*map == 0) |
|
count = 0; |
|
kunmap_atomic(map); |
|
while ((page = list_prev_entry(page, lru)) != head) { |
|
map = kmap_atomic(page) + offset; |
|
*map = SWAP_CONT_MAX | count; |
|
count = COUNT_CONTINUED; |
|
kunmap_atomic(map); |
|
} |
|
ret = count == COUNT_CONTINUED; |
|
} |
|
out: |
|
spin_unlock(&si->cont_lock); |
|
return ret; |
|
} |
|
|
|
/* |
|
* free_swap_count_continuations - swapoff free all the continuation pages |
|
* appended to the swap_map, after swap_map is quiesced, before vfree'ing it. |
|
*/ |
|
static void free_swap_count_continuations(struct swap_info_struct *si) |
|
{ |
|
pgoff_t offset; |
|
|
|
for (offset = 0; offset < si->max; offset += PAGE_SIZE) { |
|
struct page *head; |
|
head = vmalloc_to_page(si->swap_map + offset); |
|
if (page_private(head)) { |
|
struct page *page, *next; |
|
|
|
list_for_each_entry_safe(page, next, &head->lru, lru) { |
|
list_del(&page->lru); |
|
__free_page(page); |
|
} |
|
} |
|
} |
|
} |
|
|
|
#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) |
|
void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) |
|
{ |
|
struct swap_info_struct *si, *next; |
|
int nid = page_to_nid(page); |
|
|
|
if (!(gfp_mask & __GFP_IO)) |
|
return; |
|
|
|
if (!blk_cgroup_congested()) |
|
return; |
|
|
|
/* |
|
* We've already scheduled a throttle, avoid taking the global swap |
|
* lock. |
|
*/ |
|
if (current->throttle_queue) |
|
return; |
|
|
|
spin_lock(&swap_avail_lock); |
|
plist_for_each_entry_safe(si, next, &swap_avail_heads[nid], |
|
avail_lists[nid]) { |
|
if (si->bdev) { |
|
blkcg_schedule_throttle(bdev_get_queue(si->bdev), true); |
|
break; |
|
} |
|
} |
|
spin_unlock(&swap_avail_lock); |
|
} |
|
#endif |
|
|
|
static int __init swapfile_init(void) |
|
{ |
|
int nid; |
|
|
|
swap_avail_heads = kmalloc_array(nr_node_ids, sizeof(struct plist_head), |
|
GFP_KERNEL); |
|
if (!swap_avail_heads) { |
|
pr_emerg("Not enough memory for swap heads, swap is disabled\n"); |
|
return -ENOMEM; |
|
} |
|
|
|
for_each_node(nid) |
|
plist_head_init(&swap_avail_heads[nid]); |
|
|
|
return 0; |
|
} |
|
subsys_initcall(swapfile_init);
|
|
|