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![Mel Gorman](/assets/img/avatar_default.png)
make W=1 generates the following warning for z3fold_pool
mm/z3fold.c:171: warning: Function parameter or member 'zpool' not described in 'z3fold_pool'
mm/z3fold.c:171: warning: Function parameter or member 'zpool_ops' not described in 'z3fold_pool'
Commit 9a001fc19c
("z3fold: the 3-fold allocator for compressed pages")
simply did not document the fields at the time. Add rudimentary
documentation.
Link: https://lkml.kernel.org/r/20210520084809.8576-11-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1821 lines
47 KiB
C
1821 lines
47 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* z3fold.c
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*
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* Author: Vitaly Wool <vitaly.wool@konsulko.com>
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* Copyright (C) 2016, Sony Mobile Communications Inc.
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*
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* This implementation is based on zbud written by Seth Jennings.
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*
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* z3fold is an special purpose allocator for storing compressed pages. It
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* can store up to three compressed pages per page which improves the
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* compression ratio of zbud while retaining its main concepts (e. g. always
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* storing an integral number of objects per page) and simplicity.
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* It still has simple and deterministic reclaim properties that make it
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* preferable to a higher density approach (with no requirement on integral
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* number of object per page) when reclaim is used.
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*
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* As in zbud, pages are divided into "chunks". The size of the chunks is
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* fixed at compile time and is determined by NCHUNKS_ORDER below.
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*
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* z3fold doesn't export any API and is meant to be used via zpool API.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/atomic.h>
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/page-flags.h>
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#include <linux/migrate.h>
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#include <linux/node.h>
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#include <linux/compaction.h>
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#include <linux/percpu.h>
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#include <linux/mount.h>
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#include <linux/pseudo_fs.h>
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#include <linux/fs.h>
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#include <linux/preempt.h>
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#include <linux/workqueue.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/zpool.h>
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#include <linux/magic.h>
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#include <linux/kmemleak.h>
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/*
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* NCHUNKS_ORDER determines the internal allocation granularity, effectively
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* adjusting internal fragmentation. It also determines the number of
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* freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
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* allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
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* in the beginning of an allocated page are occupied by z3fold header, so
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* NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
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* which shows the max number of free chunks in z3fold page, also there will
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* be 63, or 62, respectively, freelists per pool.
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*/
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#define NCHUNKS_ORDER 6
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#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
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#define CHUNK_SIZE (1 << CHUNK_SHIFT)
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#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
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#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
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#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
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#define NCHUNKS (TOTAL_CHUNKS - ZHDR_CHUNKS)
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#define BUDDY_MASK (0x3)
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#define BUDDY_SHIFT 2
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#define SLOTS_ALIGN (0x40)
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/*****************
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* Structures
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*****************/
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struct z3fold_pool;
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struct z3fold_ops {
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int (*evict)(struct z3fold_pool *pool, unsigned long handle);
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};
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enum buddy {
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HEADLESS = 0,
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FIRST,
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MIDDLE,
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LAST,
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BUDDIES_MAX = LAST
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};
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struct z3fold_buddy_slots {
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/*
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* we are using BUDDY_MASK in handle_to_buddy etc. so there should
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* be enough slots to hold all possible variants
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*/
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unsigned long slot[BUDDY_MASK + 1];
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unsigned long pool; /* back link */
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rwlock_t lock;
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};
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#define HANDLE_FLAG_MASK (0x03)
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/*
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* struct z3fold_header - z3fold page metadata occupying first chunks of each
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* z3fold page, except for HEADLESS pages
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* @buddy: links the z3fold page into the relevant list in the
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* pool
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* @page_lock: per-page lock
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* @refcount: reference count for the z3fold page
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* @work: work_struct for page layout optimization
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* @slots: pointer to the structure holding buddy slots
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* @pool: pointer to the containing pool
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* @cpu: CPU which this page "belongs" to
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* @first_chunks: the size of the first buddy in chunks, 0 if free
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* @middle_chunks: the size of the middle buddy in chunks, 0 if free
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* @last_chunks: the size of the last buddy in chunks, 0 if free
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* @first_num: the starting number (for the first handle)
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* @mapped_count: the number of objects currently mapped
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*/
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struct z3fold_header {
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struct list_head buddy;
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spinlock_t page_lock;
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struct kref refcount;
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struct work_struct work;
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struct z3fold_buddy_slots *slots;
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struct z3fold_pool *pool;
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short cpu;
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unsigned short first_chunks;
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unsigned short middle_chunks;
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unsigned short last_chunks;
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unsigned short start_middle;
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unsigned short first_num:2;
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unsigned short mapped_count:2;
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unsigned short foreign_handles:2;
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};
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/**
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* struct z3fold_pool - stores metadata for each z3fold pool
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* @name: pool name
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* @lock: protects pool unbuddied/lru lists
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* @stale_lock: protects pool stale page list
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* @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
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* buddies; the list each z3fold page is added to depends on
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* the size of its free region.
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* @lru: list tracking the z3fold pages in LRU order by most recently
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* added buddy.
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* @stale: list of pages marked for freeing
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* @pages_nr: number of z3fold pages in the pool.
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* @c_handle: cache for z3fold_buddy_slots allocation
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* @ops: pointer to a structure of user defined operations specified at
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* pool creation time.
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* @zpool: zpool driver
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* @zpool_ops: zpool operations structure with an evict callback
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* @compact_wq: workqueue for page layout background optimization
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* @release_wq: workqueue for safe page release
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* @work: work_struct for safe page release
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* @inode: inode for z3fold pseudo filesystem
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*
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* This structure is allocated at pool creation time and maintains metadata
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* pertaining to a particular z3fold pool.
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*/
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struct z3fold_pool {
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const char *name;
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spinlock_t lock;
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spinlock_t stale_lock;
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struct list_head *unbuddied;
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struct list_head lru;
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struct list_head stale;
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atomic64_t pages_nr;
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struct kmem_cache *c_handle;
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const struct z3fold_ops *ops;
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struct zpool *zpool;
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const struct zpool_ops *zpool_ops;
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struct workqueue_struct *compact_wq;
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struct workqueue_struct *release_wq;
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struct work_struct work;
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struct inode *inode;
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};
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/*
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* Internal z3fold page flags
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*/
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enum z3fold_page_flags {
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PAGE_HEADLESS = 0,
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MIDDLE_CHUNK_MAPPED,
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NEEDS_COMPACTING,
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PAGE_STALE,
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PAGE_CLAIMED, /* by either reclaim or free */
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};
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/*
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* handle flags, go under HANDLE_FLAG_MASK
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*/
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enum z3fold_handle_flags {
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HANDLES_NOFREE = 0,
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};
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/*
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* Forward declarations
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*/
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static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
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static void compact_page_work(struct work_struct *w);
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/*****************
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* Helpers
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*****************/
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/* Converts an allocation size in bytes to size in z3fold chunks */
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static int size_to_chunks(size_t size)
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{
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return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
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}
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#define for_each_unbuddied_list(_iter, _begin) \
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for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
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static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
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gfp_t gfp)
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{
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struct z3fold_buddy_slots *slots;
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slots = kmem_cache_zalloc(pool->c_handle,
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(gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE)));
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if (slots) {
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/* It will be freed separately in free_handle(). */
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kmemleak_not_leak(slots);
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slots->pool = (unsigned long)pool;
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rwlock_init(&slots->lock);
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}
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return slots;
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}
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static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
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{
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return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
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}
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static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
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{
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return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
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}
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/* Lock a z3fold page */
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static inline void z3fold_page_lock(struct z3fold_header *zhdr)
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{
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spin_lock(&zhdr->page_lock);
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}
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/* Try to lock a z3fold page */
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static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
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{
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return spin_trylock(&zhdr->page_lock);
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}
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/* Unlock a z3fold page */
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static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
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{
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spin_unlock(&zhdr->page_lock);
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}
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/* return locked z3fold page if it's not headless */
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static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
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{
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struct z3fold_buddy_slots *slots;
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struct z3fold_header *zhdr;
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int locked = 0;
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if (!(handle & (1 << PAGE_HEADLESS))) {
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slots = handle_to_slots(handle);
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do {
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unsigned long addr;
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read_lock(&slots->lock);
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addr = *(unsigned long *)handle;
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zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
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locked = z3fold_page_trylock(zhdr);
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read_unlock(&slots->lock);
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if (locked)
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break;
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cpu_relax();
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} while (true);
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} else {
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zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
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}
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return zhdr;
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}
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static inline void put_z3fold_header(struct z3fold_header *zhdr)
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{
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struct page *page = virt_to_page(zhdr);
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if (!test_bit(PAGE_HEADLESS, &page->private))
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z3fold_page_unlock(zhdr);
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}
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static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
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{
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struct z3fold_buddy_slots *slots;
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int i;
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bool is_free;
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if (handle & (1 << PAGE_HEADLESS))
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return;
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if (WARN_ON(*(unsigned long *)handle == 0))
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return;
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slots = handle_to_slots(handle);
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write_lock(&slots->lock);
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*(unsigned long *)handle = 0;
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if (test_bit(HANDLES_NOFREE, &slots->pool)) {
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write_unlock(&slots->lock);
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return; /* simple case, nothing else to do */
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}
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if (zhdr->slots != slots)
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zhdr->foreign_handles--;
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is_free = true;
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for (i = 0; i <= BUDDY_MASK; i++) {
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if (slots->slot[i]) {
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is_free = false;
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break;
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}
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}
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write_unlock(&slots->lock);
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if (is_free) {
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struct z3fold_pool *pool = slots_to_pool(slots);
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if (zhdr->slots == slots)
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zhdr->slots = NULL;
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kmem_cache_free(pool->c_handle, slots);
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}
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}
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static int z3fold_init_fs_context(struct fs_context *fc)
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{
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return init_pseudo(fc, Z3FOLD_MAGIC) ? 0 : -ENOMEM;
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}
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static struct file_system_type z3fold_fs = {
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.name = "z3fold",
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.init_fs_context = z3fold_init_fs_context,
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.kill_sb = kill_anon_super,
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};
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static struct vfsmount *z3fold_mnt;
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static int z3fold_mount(void)
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{
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int ret = 0;
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z3fold_mnt = kern_mount(&z3fold_fs);
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if (IS_ERR(z3fold_mnt))
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ret = PTR_ERR(z3fold_mnt);
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return ret;
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}
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static void z3fold_unmount(void)
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{
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kern_unmount(z3fold_mnt);
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}
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static const struct address_space_operations z3fold_aops;
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static int z3fold_register_migration(struct z3fold_pool *pool)
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{
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pool->inode = alloc_anon_inode(z3fold_mnt->mnt_sb);
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if (IS_ERR(pool->inode)) {
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pool->inode = NULL;
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return 1;
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}
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pool->inode->i_mapping->private_data = pool;
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pool->inode->i_mapping->a_ops = &z3fold_aops;
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return 0;
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}
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static void z3fold_unregister_migration(struct z3fold_pool *pool)
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{
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if (pool->inode)
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iput(pool->inode);
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}
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/* Initializes the z3fold header of a newly allocated z3fold page */
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static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
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struct z3fold_pool *pool, gfp_t gfp)
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{
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struct z3fold_header *zhdr = page_address(page);
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struct z3fold_buddy_slots *slots;
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INIT_LIST_HEAD(&page->lru);
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clear_bit(PAGE_HEADLESS, &page->private);
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clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
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clear_bit(NEEDS_COMPACTING, &page->private);
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clear_bit(PAGE_STALE, &page->private);
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clear_bit(PAGE_CLAIMED, &page->private);
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if (headless)
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return zhdr;
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slots = alloc_slots(pool, gfp);
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if (!slots)
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return NULL;
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memset(zhdr, 0, sizeof(*zhdr));
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spin_lock_init(&zhdr->page_lock);
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kref_init(&zhdr->refcount);
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zhdr->cpu = -1;
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zhdr->slots = slots;
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zhdr->pool = pool;
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INIT_LIST_HEAD(&zhdr->buddy);
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INIT_WORK(&zhdr->work, compact_page_work);
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return zhdr;
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}
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/* Resets the struct page fields and frees the page */
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static void free_z3fold_page(struct page *page, bool headless)
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{
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if (!headless) {
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lock_page(page);
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__ClearPageMovable(page);
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unlock_page(page);
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}
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ClearPagePrivate(page);
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__free_page(page);
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}
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/* Helper function to build the index */
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static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
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{
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return (bud + zhdr->first_num) & BUDDY_MASK;
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}
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/*
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* Encodes the handle of a particular buddy within a z3fold page
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* Pool lock should be held as this function accesses first_num
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*/
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static unsigned long __encode_handle(struct z3fold_header *zhdr,
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struct z3fold_buddy_slots *slots,
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enum buddy bud)
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{
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unsigned long h = (unsigned long)zhdr;
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int idx = 0;
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/*
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* For a headless page, its handle is its pointer with the extra
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* PAGE_HEADLESS bit set
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*/
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if (bud == HEADLESS)
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return h | (1 << PAGE_HEADLESS);
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/* otherwise, return pointer to encoded handle */
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idx = __idx(zhdr, bud);
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h += idx;
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if (bud == LAST)
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h |= (zhdr->last_chunks << BUDDY_SHIFT);
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write_lock(&slots->lock);
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slots->slot[idx] = h;
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write_unlock(&slots->lock);
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return (unsigned long)&slots->slot[idx];
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}
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static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
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{
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return __encode_handle(zhdr, zhdr->slots, bud);
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}
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/* only for LAST bud, returns zero otherwise */
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static unsigned short handle_to_chunks(unsigned long handle)
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{
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struct z3fold_buddy_slots *slots = handle_to_slots(handle);
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unsigned long addr;
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read_lock(&slots->lock);
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addr = *(unsigned long *)handle;
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read_unlock(&slots->lock);
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return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
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}
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/*
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* (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
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* but that doesn't matter. because the masking will result in the
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* correct buddy number.
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*/
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static enum buddy handle_to_buddy(unsigned long handle)
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{
|
|
struct z3fold_header *zhdr;
|
|
struct z3fold_buddy_slots *slots = handle_to_slots(handle);
|
|
unsigned long addr;
|
|
|
|
read_lock(&slots->lock);
|
|
WARN_ON(handle & (1 << PAGE_HEADLESS));
|
|
addr = *(unsigned long *)handle;
|
|
read_unlock(&slots->lock);
|
|
zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
|
|
return (addr - zhdr->first_num) & BUDDY_MASK;
|
|
}
|
|
|
|
static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
|
|
{
|
|
return zhdr->pool;
|
|
}
|
|
|
|
static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
|
|
{
|
|
struct page *page = virt_to_page(zhdr);
|
|
struct z3fold_pool *pool = zhdr_to_pool(zhdr);
|
|
|
|
WARN_ON(!list_empty(&zhdr->buddy));
|
|
set_bit(PAGE_STALE, &page->private);
|
|
clear_bit(NEEDS_COMPACTING, &page->private);
|
|
spin_lock(&pool->lock);
|
|
if (!list_empty(&page->lru))
|
|
list_del_init(&page->lru);
|
|
spin_unlock(&pool->lock);
|
|
|
|
if (locked)
|
|
z3fold_page_unlock(zhdr);
|
|
|
|
spin_lock(&pool->stale_lock);
|
|
list_add(&zhdr->buddy, &pool->stale);
|
|
queue_work(pool->release_wq, &pool->work);
|
|
spin_unlock(&pool->stale_lock);
|
|
}
|
|
|
|
static void release_z3fold_page(struct kref *ref)
|
|
{
|
|
struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
|
|
refcount);
|
|
__release_z3fold_page(zhdr, false);
|
|
}
|
|
|
|
static void release_z3fold_page_locked(struct kref *ref)
|
|
{
|
|
struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
|
|
refcount);
|
|
WARN_ON(z3fold_page_trylock(zhdr));
|
|
__release_z3fold_page(zhdr, true);
|
|
}
|
|
|
|
static void release_z3fold_page_locked_list(struct kref *ref)
|
|
{
|
|
struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
|
|
refcount);
|
|
struct z3fold_pool *pool = zhdr_to_pool(zhdr);
|
|
|
|
spin_lock(&pool->lock);
|
|
list_del_init(&zhdr->buddy);
|
|
spin_unlock(&pool->lock);
|
|
|
|
WARN_ON(z3fold_page_trylock(zhdr));
|
|
__release_z3fold_page(zhdr, true);
|
|
}
|
|
|
|
static void free_pages_work(struct work_struct *w)
|
|
{
|
|
struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
|
|
|
|
spin_lock(&pool->stale_lock);
|
|
while (!list_empty(&pool->stale)) {
|
|
struct z3fold_header *zhdr = list_first_entry(&pool->stale,
|
|
struct z3fold_header, buddy);
|
|
struct page *page = virt_to_page(zhdr);
|
|
|
|
list_del(&zhdr->buddy);
|
|
if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
|
|
continue;
|
|
spin_unlock(&pool->stale_lock);
|
|
cancel_work_sync(&zhdr->work);
|
|
free_z3fold_page(page, false);
|
|
cond_resched();
|
|
spin_lock(&pool->stale_lock);
|
|
}
|
|
spin_unlock(&pool->stale_lock);
|
|
}
|
|
|
|
/*
|
|
* Returns the number of free chunks in a z3fold page.
|
|
* NB: can't be used with HEADLESS pages.
|
|
*/
|
|
static int num_free_chunks(struct z3fold_header *zhdr)
|
|
{
|
|
int nfree;
|
|
/*
|
|
* If there is a middle object, pick up the bigger free space
|
|
* either before or after it. Otherwise just subtract the number
|
|
* of chunks occupied by the first and the last objects.
|
|
*/
|
|
if (zhdr->middle_chunks != 0) {
|
|
int nfree_before = zhdr->first_chunks ?
|
|
0 : zhdr->start_middle - ZHDR_CHUNKS;
|
|
int nfree_after = zhdr->last_chunks ?
|
|
0 : TOTAL_CHUNKS -
|
|
(zhdr->start_middle + zhdr->middle_chunks);
|
|
nfree = max(nfree_before, nfree_after);
|
|
} else
|
|
nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
|
|
return nfree;
|
|
}
|
|
|
|
/* Add to the appropriate unbuddied list */
|
|
static inline void add_to_unbuddied(struct z3fold_pool *pool,
|
|
struct z3fold_header *zhdr)
|
|
{
|
|
if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
|
|
zhdr->middle_chunks == 0) {
|
|
struct list_head *unbuddied;
|
|
int freechunks = num_free_chunks(zhdr);
|
|
|
|
migrate_disable();
|
|
unbuddied = this_cpu_ptr(pool->unbuddied);
|
|
spin_lock(&pool->lock);
|
|
list_add(&zhdr->buddy, &unbuddied[freechunks]);
|
|
spin_unlock(&pool->lock);
|
|
zhdr->cpu = smp_processor_id();
|
|
migrate_enable();
|
|
}
|
|
}
|
|
|
|
static inline enum buddy get_free_buddy(struct z3fold_header *zhdr, int chunks)
|
|
{
|
|
enum buddy bud = HEADLESS;
|
|
|
|
if (zhdr->middle_chunks) {
|
|
if (!zhdr->first_chunks &&
|
|
chunks <= zhdr->start_middle - ZHDR_CHUNKS)
|
|
bud = FIRST;
|
|
else if (!zhdr->last_chunks)
|
|
bud = LAST;
|
|
} else {
|
|
if (!zhdr->first_chunks)
|
|
bud = FIRST;
|
|
else if (!zhdr->last_chunks)
|
|
bud = LAST;
|
|
else
|
|
bud = MIDDLE;
|
|
}
|
|
|
|
return bud;
|
|
}
|
|
|
|
static inline void *mchunk_memmove(struct z3fold_header *zhdr,
|
|
unsigned short dst_chunk)
|
|
{
|
|
void *beg = zhdr;
|
|
return memmove(beg + (dst_chunk << CHUNK_SHIFT),
|
|
beg + (zhdr->start_middle << CHUNK_SHIFT),
|
|
zhdr->middle_chunks << CHUNK_SHIFT);
|
|
}
|
|
|
|
static inline bool buddy_single(struct z3fold_header *zhdr)
|
|
{
|
|
return !((zhdr->first_chunks && zhdr->middle_chunks) ||
|
|
(zhdr->first_chunks && zhdr->last_chunks) ||
|
|
(zhdr->middle_chunks && zhdr->last_chunks));
|
|
}
|
|
|
|
static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
|
|
{
|
|
struct z3fold_pool *pool = zhdr_to_pool(zhdr);
|
|
void *p = zhdr;
|
|
unsigned long old_handle = 0;
|
|
size_t sz = 0;
|
|
struct z3fold_header *new_zhdr = NULL;
|
|
int first_idx = __idx(zhdr, FIRST);
|
|
int middle_idx = __idx(zhdr, MIDDLE);
|
|
int last_idx = __idx(zhdr, LAST);
|
|
unsigned short *moved_chunks = NULL;
|
|
|
|
/*
|
|
* No need to protect slots here -- all the slots are "local" and
|
|
* the page lock is already taken
|
|
*/
|
|
if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
|
|
p += ZHDR_SIZE_ALIGNED;
|
|
sz = zhdr->first_chunks << CHUNK_SHIFT;
|
|
old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
|
|
moved_chunks = &zhdr->first_chunks;
|
|
} else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
|
|
p += zhdr->start_middle << CHUNK_SHIFT;
|
|
sz = zhdr->middle_chunks << CHUNK_SHIFT;
|
|
old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
|
|
moved_chunks = &zhdr->middle_chunks;
|
|
} else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
|
|
p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
|
|
sz = zhdr->last_chunks << CHUNK_SHIFT;
|
|
old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
|
|
moved_chunks = &zhdr->last_chunks;
|
|
}
|
|
|
|
if (sz > 0) {
|
|
enum buddy new_bud = HEADLESS;
|
|
short chunks = size_to_chunks(sz);
|
|
void *q;
|
|
|
|
new_zhdr = __z3fold_alloc(pool, sz, false);
|
|
if (!new_zhdr)
|
|
return NULL;
|
|
|
|
if (WARN_ON(new_zhdr == zhdr))
|
|
goto out_fail;
|
|
|
|
new_bud = get_free_buddy(new_zhdr, chunks);
|
|
q = new_zhdr;
|
|
switch (new_bud) {
|
|
case FIRST:
|
|
new_zhdr->first_chunks = chunks;
|
|
q += ZHDR_SIZE_ALIGNED;
|
|
break;
|
|
case MIDDLE:
|
|
new_zhdr->middle_chunks = chunks;
|
|
new_zhdr->start_middle =
|
|
new_zhdr->first_chunks + ZHDR_CHUNKS;
|
|
q += new_zhdr->start_middle << CHUNK_SHIFT;
|
|
break;
|
|
case LAST:
|
|
new_zhdr->last_chunks = chunks;
|
|
q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
|
|
break;
|
|
default:
|
|
goto out_fail;
|
|
}
|
|
new_zhdr->foreign_handles++;
|
|
memcpy(q, p, sz);
|
|
write_lock(&zhdr->slots->lock);
|
|
*(unsigned long *)old_handle = (unsigned long)new_zhdr +
|
|
__idx(new_zhdr, new_bud);
|
|
if (new_bud == LAST)
|
|
*(unsigned long *)old_handle |=
|
|
(new_zhdr->last_chunks << BUDDY_SHIFT);
|
|
write_unlock(&zhdr->slots->lock);
|
|
add_to_unbuddied(pool, new_zhdr);
|
|
z3fold_page_unlock(new_zhdr);
|
|
|
|
*moved_chunks = 0;
|
|
}
|
|
|
|
return new_zhdr;
|
|
|
|
out_fail:
|
|
if (new_zhdr) {
|
|
if (kref_put(&new_zhdr->refcount, release_z3fold_page_locked))
|
|
atomic64_dec(&pool->pages_nr);
|
|
else {
|
|
add_to_unbuddied(pool, new_zhdr);
|
|
z3fold_page_unlock(new_zhdr);
|
|
}
|
|
}
|
|
return NULL;
|
|
|
|
}
|
|
|
|
#define BIG_CHUNK_GAP 3
|
|
/* Has to be called with lock held */
|
|
static int z3fold_compact_page(struct z3fold_header *zhdr)
|
|
{
|
|
struct page *page = virt_to_page(zhdr);
|
|
|
|
if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
|
|
return 0; /* can't move middle chunk, it's used */
|
|
|
|
if (unlikely(PageIsolated(page)))
|
|
return 0;
|
|
|
|
if (zhdr->middle_chunks == 0)
|
|
return 0; /* nothing to compact */
|
|
|
|
if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
|
|
/* move to the beginning */
|
|
mchunk_memmove(zhdr, ZHDR_CHUNKS);
|
|
zhdr->first_chunks = zhdr->middle_chunks;
|
|
zhdr->middle_chunks = 0;
|
|
zhdr->start_middle = 0;
|
|
zhdr->first_num++;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* moving data is expensive, so let's only do that if
|
|
* there's substantial gain (at least BIG_CHUNK_GAP chunks)
|
|
*/
|
|
if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
|
|
zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
|
|
BIG_CHUNK_GAP) {
|
|
mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
|
|
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
|
|
return 1;
|
|
} else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
|
|
TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
|
|
+ zhdr->middle_chunks) >=
|
|
BIG_CHUNK_GAP) {
|
|
unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
|
|
zhdr->middle_chunks;
|
|
mchunk_memmove(zhdr, new_start);
|
|
zhdr->start_middle = new_start;
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void do_compact_page(struct z3fold_header *zhdr, bool locked)
|
|
{
|
|
struct z3fold_pool *pool = zhdr_to_pool(zhdr);
|
|
struct page *page;
|
|
|
|
page = virt_to_page(zhdr);
|
|
if (locked)
|
|
WARN_ON(z3fold_page_trylock(zhdr));
|
|
else
|
|
z3fold_page_lock(zhdr);
|
|
if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
|
|
z3fold_page_unlock(zhdr);
|
|
return;
|
|
}
|
|
spin_lock(&pool->lock);
|
|
list_del_init(&zhdr->buddy);
|
|
spin_unlock(&pool->lock);
|
|
|
|
if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
|
|
atomic64_dec(&pool->pages_nr);
|
|
return;
|
|
}
|
|
|
|
if (test_bit(PAGE_STALE, &page->private) ||
|
|
test_and_set_bit(PAGE_CLAIMED, &page->private)) {
|
|
z3fold_page_unlock(zhdr);
|
|
return;
|
|
}
|
|
|
|
if (!zhdr->foreign_handles && buddy_single(zhdr) &&
|
|
zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
|
|
if (kref_put(&zhdr->refcount, release_z3fold_page_locked))
|
|
atomic64_dec(&pool->pages_nr);
|
|
else {
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
z3fold_page_unlock(zhdr);
|
|
}
|
|
return;
|
|
}
|
|
|
|
z3fold_compact_page(zhdr);
|
|
add_to_unbuddied(pool, zhdr);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
z3fold_page_unlock(zhdr);
|
|
}
|
|
|
|
static void compact_page_work(struct work_struct *w)
|
|
{
|
|
struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
|
|
work);
|
|
|
|
do_compact_page(zhdr, false);
|
|
}
|
|
|
|
/* returns _locked_ z3fold page header or NULL */
|
|
static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
|
|
size_t size, bool can_sleep)
|
|
{
|
|
struct z3fold_header *zhdr = NULL;
|
|
struct page *page;
|
|
struct list_head *unbuddied;
|
|
int chunks = size_to_chunks(size), i;
|
|
|
|
lookup:
|
|
migrate_disable();
|
|
/* First, try to find an unbuddied z3fold page. */
|
|
unbuddied = this_cpu_ptr(pool->unbuddied);
|
|
for_each_unbuddied_list(i, chunks) {
|
|
struct list_head *l = &unbuddied[i];
|
|
|
|
zhdr = list_first_entry_or_null(READ_ONCE(l),
|
|
struct z3fold_header, buddy);
|
|
|
|
if (!zhdr)
|
|
continue;
|
|
|
|
/* Re-check under lock. */
|
|
spin_lock(&pool->lock);
|
|
l = &unbuddied[i];
|
|
if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
|
|
struct z3fold_header, buddy)) ||
|
|
!z3fold_page_trylock(zhdr)) {
|
|
spin_unlock(&pool->lock);
|
|
zhdr = NULL;
|
|
migrate_enable();
|
|
if (can_sleep)
|
|
cond_resched();
|
|
goto lookup;
|
|
}
|
|
list_del_init(&zhdr->buddy);
|
|
zhdr->cpu = -1;
|
|
spin_unlock(&pool->lock);
|
|
|
|
page = virt_to_page(zhdr);
|
|
if (test_bit(NEEDS_COMPACTING, &page->private) ||
|
|
test_bit(PAGE_CLAIMED, &page->private)) {
|
|
z3fold_page_unlock(zhdr);
|
|
zhdr = NULL;
|
|
migrate_enable();
|
|
if (can_sleep)
|
|
cond_resched();
|
|
goto lookup;
|
|
}
|
|
|
|
/*
|
|
* this page could not be removed from its unbuddied
|
|
* list while pool lock was held, and then we've taken
|
|
* page lock so kref_put could not be called before
|
|
* we got here, so it's safe to just call kref_get()
|
|
*/
|
|
kref_get(&zhdr->refcount);
|
|
break;
|
|
}
|
|
migrate_enable();
|
|
|
|
if (!zhdr) {
|
|
int cpu;
|
|
|
|
/* look for _exact_ match on other cpus' lists */
|
|
for_each_online_cpu(cpu) {
|
|
struct list_head *l;
|
|
|
|
unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
|
|
spin_lock(&pool->lock);
|
|
l = &unbuddied[chunks];
|
|
|
|
zhdr = list_first_entry_or_null(READ_ONCE(l),
|
|
struct z3fold_header, buddy);
|
|
|
|
if (!zhdr || !z3fold_page_trylock(zhdr)) {
|
|
spin_unlock(&pool->lock);
|
|
zhdr = NULL;
|
|
continue;
|
|
}
|
|
list_del_init(&zhdr->buddy);
|
|
zhdr->cpu = -1;
|
|
spin_unlock(&pool->lock);
|
|
|
|
page = virt_to_page(zhdr);
|
|
if (test_bit(NEEDS_COMPACTING, &page->private) ||
|
|
test_bit(PAGE_CLAIMED, &page->private)) {
|
|
z3fold_page_unlock(zhdr);
|
|
zhdr = NULL;
|
|
if (can_sleep)
|
|
cond_resched();
|
|
continue;
|
|
}
|
|
kref_get(&zhdr->refcount);
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (zhdr && !zhdr->slots)
|
|
zhdr->slots = alloc_slots(pool,
|
|
can_sleep ? GFP_NOIO : GFP_ATOMIC);
|
|
return zhdr;
|
|
}
|
|
|
|
/*
|
|
* API Functions
|
|
*/
|
|
|
|
/**
|
|
* z3fold_create_pool() - create a new z3fold pool
|
|
* @name: pool name
|
|
* @gfp: gfp flags when allocating the z3fold pool structure
|
|
* @ops: user-defined operations for the z3fold pool
|
|
*
|
|
* Return: pointer to the new z3fold pool or NULL if the metadata allocation
|
|
* failed.
|
|
*/
|
|
static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp,
|
|
const struct z3fold_ops *ops)
|
|
{
|
|
struct z3fold_pool *pool = NULL;
|
|
int i, cpu;
|
|
|
|
pool = kzalloc(sizeof(struct z3fold_pool), gfp);
|
|
if (!pool)
|
|
goto out;
|
|
pool->c_handle = kmem_cache_create("z3fold_handle",
|
|
sizeof(struct z3fold_buddy_slots),
|
|
SLOTS_ALIGN, 0, NULL);
|
|
if (!pool->c_handle)
|
|
goto out_c;
|
|
spin_lock_init(&pool->lock);
|
|
spin_lock_init(&pool->stale_lock);
|
|
pool->unbuddied = __alloc_percpu(sizeof(struct list_head) * NCHUNKS,
|
|
__alignof__(struct list_head));
|
|
if (!pool->unbuddied)
|
|
goto out_pool;
|
|
for_each_possible_cpu(cpu) {
|
|
struct list_head *unbuddied =
|
|
per_cpu_ptr(pool->unbuddied, cpu);
|
|
for_each_unbuddied_list(i, 0)
|
|
INIT_LIST_HEAD(&unbuddied[i]);
|
|
}
|
|
INIT_LIST_HEAD(&pool->lru);
|
|
INIT_LIST_HEAD(&pool->stale);
|
|
atomic64_set(&pool->pages_nr, 0);
|
|
pool->name = name;
|
|
pool->compact_wq = create_singlethread_workqueue(pool->name);
|
|
if (!pool->compact_wq)
|
|
goto out_unbuddied;
|
|
pool->release_wq = create_singlethread_workqueue(pool->name);
|
|
if (!pool->release_wq)
|
|
goto out_wq;
|
|
if (z3fold_register_migration(pool))
|
|
goto out_rwq;
|
|
INIT_WORK(&pool->work, free_pages_work);
|
|
pool->ops = ops;
|
|
return pool;
|
|
|
|
out_rwq:
|
|
destroy_workqueue(pool->release_wq);
|
|
out_wq:
|
|
destroy_workqueue(pool->compact_wq);
|
|
out_unbuddied:
|
|
free_percpu(pool->unbuddied);
|
|
out_pool:
|
|
kmem_cache_destroy(pool->c_handle);
|
|
out_c:
|
|
kfree(pool);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* z3fold_destroy_pool() - destroys an existing z3fold pool
|
|
* @pool: the z3fold pool to be destroyed
|
|
*
|
|
* The pool should be emptied before this function is called.
|
|
*/
|
|
static void z3fold_destroy_pool(struct z3fold_pool *pool)
|
|
{
|
|
kmem_cache_destroy(pool->c_handle);
|
|
|
|
/*
|
|
* We need to destroy pool->compact_wq before pool->release_wq,
|
|
* as any pending work on pool->compact_wq will call
|
|
* queue_work(pool->release_wq, &pool->work).
|
|
*
|
|
* There are still outstanding pages until both workqueues are drained,
|
|
* so we cannot unregister migration until then.
|
|
*/
|
|
|
|
destroy_workqueue(pool->compact_wq);
|
|
destroy_workqueue(pool->release_wq);
|
|
z3fold_unregister_migration(pool);
|
|
free_percpu(pool->unbuddied);
|
|
kfree(pool);
|
|
}
|
|
|
|
/**
|
|
* z3fold_alloc() - allocates a region of a given size
|
|
* @pool: z3fold pool from which to allocate
|
|
* @size: size in bytes of the desired allocation
|
|
* @gfp: gfp flags used if the pool needs to grow
|
|
* @handle: handle of the new allocation
|
|
*
|
|
* This function will attempt to find a free region in the pool large enough to
|
|
* satisfy the allocation request. A search of the unbuddied lists is
|
|
* performed first. If no suitable free region is found, then a new page is
|
|
* allocated and added to the pool to satisfy the request.
|
|
*
|
|
* gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
|
|
* as z3fold pool pages.
|
|
*
|
|
* Return: 0 if success and handle is set, otherwise -EINVAL if the size or
|
|
* gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
|
|
* a new page.
|
|
*/
|
|
static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
|
|
unsigned long *handle)
|
|
{
|
|
int chunks = size_to_chunks(size);
|
|
struct z3fold_header *zhdr = NULL;
|
|
struct page *page = NULL;
|
|
enum buddy bud;
|
|
bool can_sleep = gfpflags_allow_blocking(gfp);
|
|
|
|
if (!size)
|
|
return -EINVAL;
|
|
|
|
if (size > PAGE_SIZE)
|
|
return -ENOSPC;
|
|
|
|
if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
|
|
bud = HEADLESS;
|
|
else {
|
|
retry:
|
|
zhdr = __z3fold_alloc(pool, size, can_sleep);
|
|
if (zhdr) {
|
|
bud = get_free_buddy(zhdr, chunks);
|
|
if (bud == HEADLESS) {
|
|
if (kref_put(&zhdr->refcount,
|
|
release_z3fold_page_locked))
|
|
atomic64_dec(&pool->pages_nr);
|
|
else
|
|
z3fold_page_unlock(zhdr);
|
|
pr_err("No free chunks in unbuddied\n");
|
|
WARN_ON(1);
|
|
goto retry;
|
|
}
|
|
page = virt_to_page(zhdr);
|
|
goto found;
|
|
}
|
|
bud = FIRST;
|
|
}
|
|
|
|
page = NULL;
|
|
if (can_sleep) {
|
|
spin_lock(&pool->stale_lock);
|
|
zhdr = list_first_entry_or_null(&pool->stale,
|
|
struct z3fold_header, buddy);
|
|
/*
|
|
* Before allocating a page, let's see if we can take one from
|
|
* the stale pages list. cancel_work_sync() can sleep so we
|
|
* limit this case to the contexts where we can sleep
|
|
*/
|
|
if (zhdr) {
|
|
list_del(&zhdr->buddy);
|
|
spin_unlock(&pool->stale_lock);
|
|
cancel_work_sync(&zhdr->work);
|
|
page = virt_to_page(zhdr);
|
|
} else {
|
|
spin_unlock(&pool->stale_lock);
|
|
}
|
|
}
|
|
if (!page)
|
|
page = alloc_page(gfp);
|
|
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
|
|
if (!zhdr) {
|
|
__free_page(page);
|
|
return -ENOMEM;
|
|
}
|
|
atomic64_inc(&pool->pages_nr);
|
|
|
|
if (bud == HEADLESS) {
|
|
set_bit(PAGE_HEADLESS, &page->private);
|
|
goto headless;
|
|
}
|
|
if (can_sleep) {
|
|
lock_page(page);
|
|
__SetPageMovable(page, pool->inode->i_mapping);
|
|
unlock_page(page);
|
|
} else {
|
|
if (trylock_page(page)) {
|
|
__SetPageMovable(page, pool->inode->i_mapping);
|
|
unlock_page(page);
|
|
}
|
|
}
|
|
z3fold_page_lock(zhdr);
|
|
|
|
found:
|
|
if (bud == FIRST)
|
|
zhdr->first_chunks = chunks;
|
|
else if (bud == LAST)
|
|
zhdr->last_chunks = chunks;
|
|
else {
|
|
zhdr->middle_chunks = chunks;
|
|
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
|
|
}
|
|
add_to_unbuddied(pool, zhdr);
|
|
|
|
headless:
|
|
spin_lock(&pool->lock);
|
|
/* Add/move z3fold page to beginning of LRU */
|
|
if (!list_empty(&page->lru))
|
|
list_del(&page->lru);
|
|
|
|
list_add(&page->lru, &pool->lru);
|
|
|
|
*handle = encode_handle(zhdr, bud);
|
|
spin_unlock(&pool->lock);
|
|
if (bud != HEADLESS)
|
|
z3fold_page_unlock(zhdr);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* z3fold_free() - frees the allocation associated with the given handle
|
|
* @pool: pool in which the allocation resided
|
|
* @handle: handle associated with the allocation returned by z3fold_alloc()
|
|
*
|
|
* In the case that the z3fold page in which the allocation resides is under
|
|
* reclaim, as indicated by the PG_reclaim flag being set, this function
|
|
* only sets the first|last_chunks to 0. The page is actually freed
|
|
* once both buddies are evicted (see z3fold_reclaim_page() below).
|
|
*/
|
|
static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
|
|
{
|
|
struct z3fold_header *zhdr;
|
|
struct page *page;
|
|
enum buddy bud;
|
|
bool page_claimed;
|
|
|
|
zhdr = get_z3fold_header(handle);
|
|
page = virt_to_page(zhdr);
|
|
page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
|
|
|
|
if (test_bit(PAGE_HEADLESS, &page->private)) {
|
|
/* if a headless page is under reclaim, just leave.
|
|
* NB: we use test_and_set_bit for a reason: if the bit
|
|
* has not been set before, we release this page
|
|
* immediately so we don't care about its value any more.
|
|
*/
|
|
if (!page_claimed) {
|
|
spin_lock(&pool->lock);
|
|
list_del(&page->lru);
|
|
spin_unlock(&pool->lock);
|
|
put_z3fold_header(zhdr);
|
|
free_z3fold_page(page, true);
|
|
atomic64_dec(&pool->pages_nr);
|
|
}
|
|
return;
|
|
}
|
|
|
|
/* Non-headless case */
|
|
bud = handle_to_buddy(handle);
|
|
|
|
switch (bud) {
|
|
case FIRST:
|
|
zhdr->first_chunks = 0;
|
|
break;
|
|
case MIDDLE:
|
|
zhdr->middle_chunks = 0;
|
|
break;
|
|
case LAST:
|
|
zhdr->last_chunks = 0;
|
|
break;
|
|
default:
|
|
pr_err("%s: unknown bud %d\n", __func__, bud);
|
|
WARN_ON(1);
|
|
put_z3fold_header(zhdr);
|
|
return;
|
|
}
|
|
|
|
if (!page_claimed)
|
|
free_handle(handle, zhdr);
|
|
if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
|
|
atomic64_dec(&pool->pages_nr);
|
|
return;
|
|
}
|
|
if (page_claimed) {
|
|
/* the page has not been claimed by us */
|
|
z3fold_page_unlock(zhdr);
|
|
return;
|
|
}
|
|
if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
|
|
put_z3fold_header(zhdr);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
return;
|
|
}
|
|
if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
|
|
spin_lock(&pool->lock);
|
|
list_del_init(&zhdr->buddy);
|
|
spin_unlock(&pool->lock);
|
|
zhdr->cpu = -1;
|
|
kref_get(&zhdr->refcount);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
do_compact_page(zhdr, true);
|
|
return;
|
|
}
|
|
kref_get(&zhdr->refcount);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
|
|
put_z3fold_header(zhdr);
|
|
}
|
|
|
|
/**
|
|
* z3fold_reclaim_page() - evicts allocations from a pool page and frees it
|
|
* @pool: pool from which a page will attempt to be evicted
|
|
* @retries: number of pages on the LRU list for which eviction will
|
|
* be attempted before failing
|
|
*
|
|
* z3fold reclaim is different from normal system reclaim in that it is done
|
|
* from the bottom, up. This is because only the bottom layer, z3fold, has
|
|
* information on how the allocations are organized within each z3fold page.
|
|
* This has the potential to create interesting locking situations between
|
|
* z3fold and the user, however.
|
|
*
|
|
* To avoid these, this is how z3fold_reclaim_page() should be called:
|
|
*
|
|
* The user detects a page should be reclaimed and calls z3fold_reclaim_page().
|
|
* z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
|
|
* call the user-defined eviction handler with the pool and handle as
|
|
* arguments.
|
|
*
|
|
* If the handle can not be evicted, the eviction handler should return
|
|
* non-zero. z3fold_reclaim_page() will add the z3fold page back to the
|
|
* appropriate list and try the next z3fold page on the LRU up to
|
|
* a user defined number of retries.
|
|
*
|
|
* If the handle is successfully evicted, the eviction handler should
|
|
* return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
|
|
* contains logic to delay freeing the page if the page is under reclaim,
|
|
* as indicated by the setting of the PG_reclaim flag on the underlying page.
|
|
*
|
|
* If all buddies in the z3fold page are successfully evicted, then the
|
|
* z3fold page can be freed.
|
|
*
|
|
* Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
|
|
* no pages to evict or an eviction handler is not registered, -EAGAIN if
|
|
* the retry limit was hit.
|
|
*/
|
|
static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
|
|
{
|
|
int i, ret = -1;
|
|
struct z3fold_header *zhdr = NULL;
|
|
struct page *page = NULL;
|
|
struct list_head *pos;
|
|
unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
|
|
struct z3fold_buddy_slots slots __attribute__((aligned(SLOTS_ALIGN)));
|
|
|
|
rwlock_init(&slots.lock);
|
|
slots.pool = (unsigned long)pool | (1 << HANDLES_NOFREE);
|
|
|
|
spin_lock(&pool->lock);
|
|
if (!pool->ops || !pool->ops->evict || retries == 0) {
|
|
spin_unlock(&pool->lock);
|
|
return -EINVAL;
|
|
}
|
|
for (i = 0; i < retries; i++) {
|
|
if (list_empty(&pool->lru)) {
|
|
spin_unlock(&pool->lock);
|
|
return -EINVAL;
|
|
}
|
|
list_for_each_prev(pos, &pool->lru) {
|
|
page = list_entry(pos, struct page, lru);
|
|
|
|
zhdr = page_address(page);
|
|
if (test_bit(PAGE_HEADLESS, &page->private)) {
|
|
/*
|
|
* For non-headless pages, we wait to do this
|
|
* until we have the page lock to avoid racing
|
|
* with __z3fold_alloc(). Headless pages don't
|
|
* have a lock (and __z3fold_alloc() will never
|
|
* see them), but we still need to test and set
|
|
* PAGE_CLAIMED to avoid racing with
|
|
* z3fold_free(), so just do it now before
|
|
* leaving the loop.
|
|
*/
|
|
if (test_and_set_bit(PAGE_CLAIMED, &page->private))
|
|
continue;
|
|
|
|
break;
|
|
}
|
|
|
|
if (kref_get_unless_zero(&zhdr->refcount) == 0) {
|
|
zhdr = NULL;
|
|
break;
|
|
}
|
|
if (!z3fold_page_trylock(zhdr)) {
|
|
if (kref_put(&zhdr->refcount,
|
|
release_z3fold_page))
|
|
atomic64_dec(&pool->pages_nr);
|
|
zhdr = NULL;
|
|
continue; /* can't evict at this point */
|
|
}
|
|
|
|
/* test_and_set_bit is of course atomic, but we still
|
|
* need to do it under page lock, otherwise checking
|
|
* that bit in __z3fold_alloc wouldn't make sense
|
|
*/
|
|
if (zhdr->foreign_handles ||
|
|
test_and_set_bit(PAGE_CLAIMED, &page->private)) {
|
|
if (kref_put(&zhdr->refcount,
|
|
release_z3fold_page_locked))
|
|
atomic64_dec(&pool->pages_nr);
|
|
else
|
|
z3fold_page_unlock(zhdr);
|
|
zhdr = NULL;
|
|
continue; /* can't evict such page */
|
|
}
|
|
list_del_init(&zhdr->buddy);
|
|
zhdr->cpu = -1;
|
|
break;
|
|
}
|
|
|
|
if (!zhdr)
|
|
break;
|
|
|
|
list_del_init(&page->lru);
|
|
spin_unlock(&pool->lock);
|
|
|
|
if (!test_bit(PAGE_HEADLESS, &page->private)) {
|
|
/*
|
|
* We need encode the handles before unlocking, and
|
|
* use our local slots structure because z3fold_free
|
|
* can zero out zhdr->slots and we can't do much
|
|
* about that
|
|
*/
|
|
first_handle = 0;
|
|
last_handle = 0;
|
|
middle_handle = 0;
|
|
memset(slots.slot, 0, sizeof(slots.slot));
|
|
if (zhdr->first_chunks)
|
|
first_handle = __encode_handle(zhdr, &slots,
|
|
FIRST);
|
|
if (zhdr->middle_chunks)
|
|
middle_handle = __encode_handle(zhdr, &slots,
|
|
MIDDLE);
|
|
if (zhdr->last_chunks)
|
|
last_handle = __encode_handle(zhdr, &slots,
|
|
LAST);
|
|
/*
|
|
* it's safe to unlock here because we hold a
|
|
* reference to this page
|
|
*/
|
|
z3fold_page_unlock(zhdr);
|
|
} else {
|
|
first_handle = encode_handle(zhdr, HEADLESS);
|
|
last_handle = middle_handle = 0;
|
|
}
|
|
/* Issue the eviction callback(s) */
|
|
if (middle_handle) {
|
|
ret = pool->ops->evict(pool, middle_handle);
|
|
if (ret)
|
|
goto next;
|
|
}
|
|
if (first_handle) {
|
|
ret = pool->ops->evict(pool, first_handle);
|
|
if (ret)
|
|
goto next;
|
|
}
|
|
if (last_handle) {
|
|
ret = pool->ops->evict(pool, last_handle);
|
|
if (ret)
|
|
goto next;
|
|
}
|
|
next:
|
|
if (test_bit(PAGE_HEADLESS, &page->private)) {
|
|
if (ret == 0) {
|
|
free_z3fold_page(page, true);
|
|
atomic64_dec(&pool->pages_nr);
|
|
return 0;
|
|
}
|
|
spin_lock(&pool->lock);
|
|
list_add(&page->lru, &pool->lru);
|
|
spin_unlock(&pool->lock);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
} else {
|
|
struct z3fold_buddy_slots *slots = zhdr->slots;
|
|
z3fold_page_lock(zhdr);
|
|
if (kref_put(&zhdr->refcount,
|
|
release_z3fold_page_locked)) {
|
|
kmem_cache_free(pool->c_handle, slots);
|
|
atomic64_dec(&pool->pages_nr);
|
|
return 0;
|
|
}
|
|
/*
|
|
* if we are here, the page is still not completely
|
|
* free. Take the global pool lock then to be able
|
|
* to add it back to the lru list
|
|
*/
|
|
spin_lock(&pool->lock);
|
|
list_add(&page->lru, &pool->lru);
|
|
spin_unlock(&pool->lock);
|
|
z3fold_page_unlock(zhdr);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
}
|
|
|
|
/* We started off locked to we need to lock the pool back */
|
|
spin_lock(&pool->lock);
|
|
}
|
|
spin_unlock(&pool->lock);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
/**
|
|
* z3fold_map() - maps the allocation associated with the given handle
|
|
* @pool: pool in which the allocation resides
|
|
* @handle: handle associated with the allocation to be mapped
|
|
*
|
|
* Extracts the buddy number from handle and constructs the pointer to the
|
|
* correct starting chunk within the page.
|
|
*
|
|
* Returns: a pointer to the mapped allocation
|
|
*/
|
|
static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
|
|
{
|
|
struct z3fold_header *zhdr;
|
|
struct page *page;
|
|
void *addr;
|
|
enum buddy buddy;
|
|
|
|
zhdr = get_z3fold_header(handle);
|
|
addr = zhdr;
|
|
page = virt_to_page(zhdr);
|
|
|
|
if (test_bit(PAGE_HEADLESS, &page->private))
|
|
goto out;
|
|
|
|
buddy = handle_to_buddy(handle);
|
|
switch (buddy) {
|
|
case FIRST:
|
|
addr += ZHDR_SIZE_ALIGNED;
|
|
break;
|
|
case MIDDLE:
|
|
addr += zhdr->start_middle << CHUNK_SHIFT;
|
|
set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
|
|
break;
|
|
case LAST:
|
|
addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
|
|
break;
|
|
default:
|
|
pr_err("unknown buddy id %d\n", buddy);
|
|
WARN_ON(1);
|
|
addr = NULL;
|
|
break;
|
|
}
|
|
|
|
if (addr)
|
|
zhdr->mapped_count++;
|
|
out:
|
|
put_z3fold_header(zhdr);
|
|
return addr;
|
|
}
|
|
|
|
/**
|
|
* z3fold_unmap() - unmaps the allocation associated with the given handle
|
|
* @pool: pool in which the allocation resides
|
|
* @handle: handle associated with the allocation to be unmapped
|
|
*/
|
|
static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
|
|
{
|
|
struct z3fold_header *zhdr;
|
|
struct page *page;
|
|
enum buddy buddy;
|
|
|
|
zhdr = get_z3fold_header(handle);
|
|
page = virt_to_page(zhdr);
|
|
|
|
if (test_bit(PAGE_HEADLESS, &page->private))
|
|
return;
|
|
|
|
buddy = handle_to_buddy(handle);
|
|
if (buddy == MIDDLE)
|
|
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
|
|
zhdr->mapped_count--;
|
|
put_z3fold_header(zhdr);
|
|
}
|
|
|
|
/**
|
|
* z3fold_get_pool_size() - gets the z3fold pool size in pages
|
|
* @pool: pool whose size is being queried
|
|
*
|
|
* Returns: size in pages of the given pool.
|
|
*/
|
|
static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
|
|
{
|
|
return atomic64_read(&pool->pages_nr);
|
|
}
|
|
|
|
static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
|
|
{
|
|
struct z3fold_header *zhdr;
|
|
struct z3fold_pool *pool;
|
|
|
|
VM_BUG_ON_PAGE(!PageMovable(page), page);
|
|
VM_BUG_ON_PAGE(PageIsolated(page), page);
|
|
|
|
if (test_bit(PAGE_HEADLESS, &page->private))
|
|
return false;
|
|
|
|
zhdr = page_address(page);
|
|
z3fold_page_lock(zhdr);
|
|
if (test_bit(NEEDS_COMPACTING, &page->private) ||
|
|
test_bit(PAGE_STALE, &page->private))
|
|
goto out;
|
|
|
|
if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
|
|
goto out;
|
|
|
|
if (test_and_set_bit(PAGE_CLAIMED, &page->private))
|
|
goto out;
|
|
pool = zhdr_to_pool(zhdr);
|
|
spin_lock(&pool->lock);
|
|
if (!list_empty(&zhdr->buddy))
|
|
list_del_init(&zhdr->buddy);
|
|
if (!list_empty(&page->lru))
|
|
list_del_init(&page->lru);
|
|
spin_unlock(&pool->lock);
|
|
|
|
kref_get(&zhdr->refcount);
|
|
z3fold_page_unlock(zhdr);
|
|
return true;
|
|
|
|
out:
|
|
z3fold_page_unlock(zhdr);
|
|
return false;
|
|
}
|
|
|
|
static int z3fold_page_migrate(struct address_space *mapping, struct page *newpage,
|
|
struct page *page, enum migrate_mode mode)
|
|
{
|
|
struct z3fold_header *zhdr, *new_zhdr;
|
|
struct z3fold_pool *pool;
|
|
struct address_space *new_mapping;
|
|
|
|
VM_BUG_ON_PAGE(!PageMovable(page), page);
|
|
VM_BUG_ON_PAGE(!PageIsolated(page), page);
|
|
VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
|
|
|
|
zhdr = page_address(page);
|
|
pool = zhdr_to_pool(zhdr);
|
|
|
|
if (!z3fold_page_trylock(zhdr))
|
|
return -EAGAIN;
|
|
if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
|
|
z3fold_page_unlock(zhdr);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
return -EBUSY;
|
|
}
|
|
if (work_pending(&zhdr->work)) {
|
|
z3fold_page_unlock(zhdr);
|
|
return -EAGAIN;
|
|
}
|
|
new_zhdr = page_address(newpage);
|
|
memcpy(new_zhdr, zhdr, PAGE_SIZE);
|
|
newpage->private = page->private;
|
|
page->private = 0;
|
|
z3fold_page_unlock(zhdr);
|
|
spin_lock_init(&new_zhdr->page_lock);
|
|
INIT_WORK(&new_zhdr->work, compact_page_work);
|
|
/*
|
|
* z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
|
|
* so we only have to reinitialize it.
|
|
*/
|
|
INIT_LIST_HEAD(&new_zhdr->buddy);
|
|
new_mapping = page_mapping(page);
|
|
__ClearPageMovable(page);
|
|
ClearPagePrivate(page);
|
|
|
|
get_page(newpage);
|
|
z3fold_page_lock(new_zhdr);
|
|
if (new_zhdr->first_chunks)
|
|
encode_handle(new_zhdr, FIRST);
|
|
if (new_zhdr->last_chunks)
|
|
encode_handle(new_zhdr, LAST);
|
|
if (new_zhdr->middle_chunks)
|
|
encode_handle(new_zhdr, MIDDLE);
|
|
set_bit(NEEDS_COMPACTING, &newpage->private);
|
|
new_zhdr->cpu = smp_processor_id();
|
|
spin_lock(&pool->lock);
|
|
list_add(&newpage->lru, &pool->lru);
|
|
spin_unlock(&pool->lock);
|
|
__SetPageMovable(newpage, new_mapping);
|
|
z3fold_page_unlock(new_zhdr);
|
|
|
|
queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
|
|
|
|
page_mapcount_reset(page);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
put_page(page);
|
|
return 0;
|
|
}
|
|
|
|
static void z3fold_page_putback(struct page *page)
|
|
{
|
|
struct z3fold_header *zhdr;
|
|
struct z3fold_pool *pool;
|
|
|
|
zhdr = page_address(page);
|
|
pool = zhdr_to_pool(zhdr);
|
|
|
|
z3fold_page_lock(zhdr);
|
|
if (!list_empty(&zhdr->buddy))
|
|
list_del_init(&zhdr->buddy);
|
|
INIT_LIST_HEAD(&page->lru);
|
|
if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
|
|
atomic64_dec(&pool->pages_nr);
|
|
return;
|
|
}
|
|
spin_lock(&pool->lock);
|
|
list_add(&page->lru, &pool->lru);
|
|
spin_unlock(&pool->lock);
|
|
clear_bit(PAGE_CLAIMED, &page->private);
|
|
z3fold_page_unlock(zhdr);
|
|
}
|
|
|
|
static const struct address_space_operations z3fold_aops = {
|
|
.isolate_page = z3fold_page_isolate,
|
|
.migratepage = z3fold_page_migrate,
|
|
.putback_page = z3fold_page_putback,
|
|
};
|
|
|
|
/*****************
|
|
* zpool
|
|
****************/
|
|
|
|
static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
|
|
{
|
|
if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
|
|
return pool->zpool_ops->evict(pool->zpool, handle);
|
|
else
|
|
return -ENOENT;
|
|
}
|
|
|
|
static const struct z3fold_ops z3fold_zpool_ops = {
|
|
.evict = z3fold_zpool_evict
|
|
};
|
|
|
|
static void *z3fold_zpool_create(const char *name, gfp_t gfp,
|
|
const struct zpool_ops *zpool_ops,
|
|
struct zpool *zpool)
|
|
{
|
|
struct z3fold_pool *pool;
|
|
|
|
pool = z3fold_create_pool(name, gfp,
|
|
zpool_ops ? &z3fold_zpool_ops : NULL);
|
|
if (pool) {
|
|
pool->zpool = zpool;
|
|
pool->zpool_ops = zpool_ops;
|
|
}
|
|
return pool;
|
|
}
|
|
|
|
static void z3fold_zpool_destroy(void *pool)
|
|
{
|
|
z3fold_destroy_pool(pool);
|
|
}
|
|
|
|
static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
|
|
unsigned long *handle)
|
|
{
|
|
return z3fold_alloc(pool, size, gfp, handle);
|
|
}
|
|
static void z3fold_zpool_free(void *pool, unsigned long handle)
|
|
{
|
|
z3fold_free(pool, handle);
|
|
}
|
|
|
|
static int z3fold_zpool_shrink(void *pool, unsigned int pages,
|
|
unsigned int *reclaimed)
|
|
{
|
|
unsigned int total = 0;
|
|
int ret = -EINVAL;
|
|
|
|
while (total < pages) {
|
|
ret = z3fold_reclaim_page(pool, 8);
|
|
if (ret < 0)
|
|
break;
|
|
total++;
|
|
}
|
|
|
|
if (reclaimed)
|
|
*reclaimed = total;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void *z3fold_zpool_map(void *pool, unsigned long handle,
|
|
enum zpool_mapmode mm)
|
|
{
|
|
return z3fold_map(pool, handle);
|
|
}
|
|
static void z3fold_zpool_unmap(void *pool, unsigned long handle)
|
|
{
|
|
z3fold_unmap(pool, handle);
|
|
}
|
|
|
|
static u64 z3fold_zpool_total_size(void *pool)
|
|
{
|
|
return z3fold_get_pool_size(pool) * PAGE_SIZE;
|
|
}
|
|
|
|
static struct zpool_driver z3fold_zpool_driver = {
|
|
.type = "z3fold",
|
|
.sleep_mapped = true,
|
|
.owner = THIS_MODULE,
|
|
.create = z3fold_zpool_create,
|
|
.destroy = z3fold_zpool_destroy,
|
|
.malloc = z3fold_zpool_malloc,
|
|
.free = z3fold_zpool_free,
|
|
.shrink = z3fold_zpool_shrink,
|
|
.map = z3fold_zpool_map,
|
|
.unmap = z3fold_zpool_unmap,
|
|
.total_size = z3fold_zpool_total_size,
|
|
};
|
|
|
|
MODULE_ALIAS("zpool-z3fold");
|
|
|
|
static int __init init_z3fold(void)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Make sure the z3fold header is not larger than the page size and
|
|
* there has remaining spaces for its buddy.
|
|
*/
|
|
BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
|
|
ret = z3fold_mount();
|
|
if (ret)
|
|
return ret;
|
|
|
|
zpool_register_driver(&z3fold_zpool_driver);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit exit_z3fold(void)
|
|
{
|
|
z3fold_unmount();
|
|
zpool_unregister_driver(&z3fold_zpool_driver);
|
|
}
|
|
|
|
module_init(init_z3fold);
|
|
module_exit(exit_z3fold);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
|
|
MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
|