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1821 lines
47 KiB
1821 lines
47 KiB
// 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 <[email protected]> |
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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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|
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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|
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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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/* |
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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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|
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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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|
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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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/***************** |
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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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/* |
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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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/** |
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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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/* |
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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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/* |
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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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/* |
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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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/***************** |
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* Helpers |
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*****************/ |
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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|
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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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/* |
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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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/* |
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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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|
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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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|
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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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|
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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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|
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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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|
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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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/* |
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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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{ |
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struct z3fold_header *zhdr; |
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struct z3fold_buddy_slots *slots = handle_to_slots(handle); |
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unsigned long addr; |
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|
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read_lock(&slots->lock); |
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WARN_ON(handle & (1 << PAGE_HEADLESS)); |
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addr = *(unsigned long *)handle; |
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read_unlock(&slots->lock); |
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zhdr = (struct z3fold_header *)(addr & PAGE_MASK); |
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return (addr - zhdr->first_num) & BUDDY_MASK; |
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} |
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|
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static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr) |
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{ |
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return zhdr->pool; |
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} |
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|
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static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked) |
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{ |
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struct page *page = virt_to_page(zhdr); |
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struct z3fold_pool *pool = zhdr_to_pool(zhdr); |
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|
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WARN_ON(!list_empty(&zhdr->buddy)); |
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set_bit(PAGE_STALE, &page->private); |
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clear_bit(NEEDS_COMPACTING, &page->private); |
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spin_lock(&pool->lock); |
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if (!list_empty(&page->lru)) |
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list_del_init(&page->lru); |
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spin_unlock(&pool->lock); |
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|
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if (locked) |
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z3fold_page_unlock(zhdr); |
|
|
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spin_lock(&pool->stale_lock); |
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list_add(&zhdr->buddy, &pool->stale); |
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queue_work(pool->release_wq, &pool->work); |
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spin_unlock(&pool->stale_lock); |
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} |
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|
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static void release_z3fold_page(struct kref *ref) |
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{ |
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struct z3fold_header *zhdr = container_of(ref, struct z3fold_header, |
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refcount); |
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__release_z3fold_page(zhdr, false); |
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} |
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|
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static void release_z3fold_page_locked(struct kref *ref) |
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{ |
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struct z3fold_header *zhdr = container_of(ref, struct z3fold_header, |
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refcount); |
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WARN_ON(z3fold_page_trylock(zhdr)); |
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__release_z3fold_page(zhdr, true); |
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} |
|
|
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static void release_z3fold_page_locked_list(struct kref *ref) |
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{ |
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struct z3fold_header *zhdr = container_of(ref, struct z3fold_header, |
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refcount); |
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struct z3fold_pool *pool = zhdr_to_pool(zhdr); |
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|
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spin_lock(&pool->lock); |
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list_del_init(&zhdr->buddy); |
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spin_unlock(&pool->lock); |
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|
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WARN_ON(z3fold_page_trylock(zhdr)); |
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__release_z3fold_page(zhdr, true); |
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} |
|
|
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static void free_pages_work(struct work_struct *w) |
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{ |
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struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work); |
|
|
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spin_lock(&pool->stale_lock); |
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while (!list_empty(&pool->stale)) { |
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struct z3fold_header *zhdr = list_first_entry(&pool->stale, |
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struct z3fold_header, buddy); |
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struct page *page = virt_to_page(zhdr); |
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|
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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 = { |
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.isolate_page = z3fold_page_isolate, |
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.migratepage = z3fold_page_migrate, |
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.putback_page = z3fold_page_putback, |
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}; |
|
|
|
/***************** |
|
* zpool |
|
****************/ |
|
|
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static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle) |
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{ |
|
if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict) |
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return pool->zpool_ops->evict(pool->zpool, handle); |
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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 <[email protected]>"); |
|
MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
|
|
|