From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/mm/z3fold.c | 1119 +++++++++++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 899 insertions(+), 220 deletions(-)
diff --git a/kernel/mm/z3fold.c b/kernel/mm/z3fold.c
index aee9b0b..912ac9a 100644
--- a/kernel/mm/z3fold.c
+++ b/kernel/mm/z3fold.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* z3fold.c
*
@@ -24,60 +25,25 @@
#include <linux/atomic.h>
#include <linux/sched.h>
+#include <linux/cpumask.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/page-flags.h>
+#include <linux/migrate.h>
+#include <linux/node.h>
+#include <linux/compaction.h>
#include <linux/percpu.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/fs.h>
#include <linux/preempt.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/zpool.h>
-
-/*****************
- * Structures
-*****************/
-struct z3fold_pool;
-struct z3fold_ops {
- int (*evict)(struct z3fold_pool *pool, unsigned long handle);
-};
-
-enum buddy {
- HEADLESS = 0,
- FIRST,
- MIDDLE,
- LAST,
- BUDDIES_MAX
-};
-
-/*
- * struct z3fold_header - z3fold page metadata occupying first chunks of each
- * z3fold page, except for HEADLESS pages
- * @buddy: links the z3fold page into the relevant list in the
- * pool
- * @page_lock: per-page lock
- * @refcount: reference count for the z3fold page
- * @work: work_struct for page layout optimization
- * @pool: pointer to the pool which this page belongs to
- * @cpu: CPU which this page "belongs" to
- * @first_chunks: the size of the first buddy in chunks, 0 if free
- * @middle_chunks: the size of the middle buddy in chunks, 0 if free
- * @last_chunks: the size of the last buddy in chunks, 0 if free
- * @first_num: the starting number (for the first handle)
- */
-struct z3fold_header {
- struct list_head buddy;
- spinlock_t page_lock;
- struct kref refcount;
- struct work_struct work;
- struct z3fold_pool *pool;
- short cpu;
- unsigned short first_chunks;
- unsigned short middle_chunks;
- unsigned short last_chunks;
- unsigned short start_middle;
- unsigned short first_num:2;
-};
+#include <linux/magic.h>
+#include <linux/kmemleak.h>
/*
* NCHUNKS_ORDER determines the internal allocation granularity, effectively
@@ -100,6 +66,68 @@
#define BUDDY_MASK (0x3)
#define BUDDY_SHIFT 2
+#define SLOTS_ALIGN (0x40)
+
+/*****************
+ * Structures
+*****************/
+struct z3fold_pool;
+struct z3fold_ops {
+ int (*evict)(struct z3fold_pool *pool, unsigned long handle);
+};
+
+enum buddy {
+ HEADLESS = 0,
+ FIRST,
+ MIDDLE,
+ LAST,
+ BUDDIES_MAX = LAST
+};
+
+struct z3fold_buddy_slots {
+ /*
+ * we are using BUDDY_MASK in handle_to_buddy etc. so there should
+ * be enough slots to hold all possible variants
+ */
+ unsigned long slot[BUDDY_MASK + 1];
+ unsigned long pool; /* back link */
+ rwlock_t lock;
+};
+#define HANDLE_FLAG_MASK (0x03)
+
+/*
+ * struct z3fold_header - z3fold page metadata occupying first chunks of each
+ * z3fold page, except for HEADLESS pages
+ * @buddy: links the z3fold page into the relevant list in the
+ * pool
+ * @page_lock: per-page lock
+ * @refcount: reference count for the z3fold page
+ * @work: work_struct for page layout optimization
+ * @slots: pointer to the structure holding buddy slots
+ * @pool: pointer to the containing pool
+ * @cpu: CPU which this page "belongs" to
+ * @first_chunks: the size of the first buddy in chunks, 0 if free
+ * @middle_chunks: the size of the middle buddy in chunks, 0 if free
+ * @last_chunks: the size of the last buddy in chunks, 0 if free
+ * @first_num: the starting number (for the first handle)
+ * @mapped_count: the number of objects currently mapped
+ */
+struct z3fold_header {
+ struct list_head buddy;
+ spinlock_t page_lock;
+ struct kref refcount;
+ struct work_struct work;
+ struct z3fold_buddy_slots *slots;
+ struct z3fold_pool *pool;
+ short cpu;
+ unsigned short first_chunks;
+ unsigned short middle_chunks;
+ unsigned short last_chunks;
+ unsigned short start_middle;
+ unsigned short first_num:2;
+ unsigned short mapped_count:2;
+ unsigned short foreign_handles:2;
+};
/**
* struct z3fold_pool - stores metadata for each z3fold pool
@@ -113,11 +141,13 @@
* added buddy.
* @stale: list of pages marked for freeing
* @pages_nr: number of z3fold pages in the pool.
+ * @c_handle: cache for z3fold_buddy_slots allocation
* @ops: pointer to a structure of user defined operations specified at
* pool creation time.
* @compact_wq: workqueue for page layout background optimization
* @release_wq: workqueue for safe page release
* @work: work_struct for safe page release
+ * @inode: inode for z3fold pseudo filesystem
*
* This structure is allocated at pool creation time and maintains metadata
* pertaining to a particular z3fold pool.
@@ -130,12 +160,14 @@
struct list_head lru;
struct list_head stale;
atomic64_t pages_nr;
+ struct kmem_cache *c_handle;
const struct z3fold_ops *ops;
struct zpool *zpool;
const struct zpool_ops *zpool_ops;
struct workqueue_struct *compact_wq;
struct workqueue_struct *release_wq;
struct work_struct work;
+ struct inode *inode;
};
/*
@@ -148,6 +180,19 @@
PAGE_STALE,
PAGE_CLAIMED, /* by either reclaim or free */
};
+
+/*
+ * handle flags, go under HANDLE_FLAG_MASK
+ */
+enum z3fold_handle_flags {
+ HANDLES_NOFREE = 0,
+};
+
+/*
+ * Forward declarations
+ */
+static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
+static void compact_page_work(struct work_struct *w);
/*****************
* Helpers
@@ -162,39 +207,32 @@
#define for_each_unbuddied_list(_iter, _begin) \
for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
-static void compact_page_work(struct work_struct *w);
-
-/* Initializes the z3fold header of a newly allocated z3fold page */
-static struct z3fold_header *init_z3fold_page(struct page *page,
- struct z3fold_pool *pool)
+static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
+ gfp_t gfp)
{
- struct z3fold_header *zhdr = page_address(page);
+ struct z3fold_buddy_slots *slots;
- INIT_LIST_HEAD(&page->lru);
- clear_bit(PAGE_HEADLESS, &page->private);
- clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
- clear_bit(NEEDS_COMPACTING, &page->private);
- clear_bit(PAGE_STALE, &page->private);
- clear_bit(PAGE_CLAIMED, &page->private);
+ slots = kmem_cache_zalloc(pool->c_handle,
+ (gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE)));
- spin_lock_init(&zhdr->page_lock);
- kref_init(&zhdr->refcount);
- zhdr->first_chunks = 0;
- zhdr->middle_chunks = 0;
- zhdr->last_chunks = 0;
- zhdr->first_num = 0;
- zhdr->start_middle = 0;
- zhdr->cpu = -1;
- zhdr->pool = pool;
- INIT_LIST_HEAD(&zhdr->buddy);
- INIT_WORK(&zhdr->work, compact_page_work);
- return zhdr;
+ if (slots) {
+ /* It will be freed separately in free_handle(). */
+ kmemleak_not_leak(slots);
+ slots->pool = (unsigned long)pool;
+ rwlock_init(&slots->lock);
+ }
+
+ return slots;
}
-/* Resets the struct page fields and frees the page */
-static void free_z3fold_page(struct page *page)
+static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
{
- __free_page(page);
+ return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
+}
+
+static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
+{
+ return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
}
/* Lock a z3fold page */
@@ -215,33 +253,246 @@
spin_unlock(&zhdr->page_lock);
}
+
+static inline struct z3fold_header *__get_z3fold_header(unsigned long handle,
+ bool lock)
+{
+ struct z3fold_buddy_slots *slots;
+ struct z3fold_header *zhdr;
+ int locked = 0;
+
+ if (!(handle & (1 << PAGE_HEADLESS))) {
+ slots = handle_to_slots(handle);
+ do {
+ unsigned long addr;
+
+ read_lock(&slots->lock);
+ addr = *(unsigned long *)handle;
+ zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
+ if (lock)
+ locked = z3fold_page_trylock(zhdr);
+ read_unlock(&slots->lock);
+ if (locked)
+ break;
+ cpu_relax();
+ } while (lock);
+ } else {
+ zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
+ }
+
+ return zhdr;
+}
+
+/* Returns the z3fold page where a given handle is stored */
+static inline struct z3fold_header *handle_to_z3fold_header(unsigned long h)
+{
+ return __get_z3fold_header(h, false);
+}
+
+/* return locked z3fold page if it's not headless */
+static inline struct z3fold_header *get_z3fold_header(unsigned long h)
+{
+ return __get_z3fold_header(h, true);
+}
+
+static inline void put_z3fold_header(struct z3fold_header *zhdr)
+{
+ struct page *page = virt_to_page(zhdr);
+
+ if (!test_bit(PAGE_HEADLESS, &page->private))
+ z3fold_page_unlock(zhdr);
+}
+
+static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
+{
+ struct z3fold_buddy_slots *slots;
+ int i;
+ bool is_free;
+
+ if (handle & (1 << PAGE_HEADLESS))
+ return;
+
+ if (WARN_ON(*(unsigned long *)handle == 0))
+ return;
+
+ slots = handle_to_slots(handle);
+ write_lock(&slots->lock);
+ *(unsigned long *)handle = 0;
+
+ if (test_bit(HANDLES_NOFREE, &slots->pool)) {
+ write_unlock(&slots->lock);
+ return; /* simple case, nothing else to do */
+ }
+
+ if (zhdr->slots != slots)
+ zhdr->foreign_handles--;
+
+ is_free = true;
+ for (i = 0; i <= BUDDY_MASK; i++) {
+ if (slots->slot[i]) {
+ is_free = false;
+ break;
+ }
+ }
+ write_unlock(&slots->lock);
+
+ if (is_free) {
+ struct z3fold_pool *pool = slots_to_pool(slots);
+
+ if (zhdr->slots == slots)
+ zhdr->slots = NULL;
+ kmem_cache_free(pool->c_handle, slots);
+ }
+}
+
+static int z3fold_init_fs_context(struct fs_context *fc)
+{
+ return init_pseudo(fc, Z3FOLD_MAGIC) ? 0 : -ENOMEM;
+}
+
+static struct file_system_type z3fold_fs = {
+ .name = "z3fold",
+ .init_fs_context = z3fold_init_fs_context,
+ .kill_sb = kill_anon_super,
+};
+
+static struct vfsmount *z3fold_mnt;
+static int z3fold_mount(void)
+{
+ int ret = 0;
+
+ z3fold_mnt = kern_mount(&z3fold_fs);
+ if (IS_ERR(z3fold_mnt))
+ ret = PTR_ERR(z3fold_mnt);
+
+ return ret;
+}
+
+static void z3fold_unmount(void)
+{
+ kern_unmount(z3fold_mnt);
+}
+
+static const struct address_space_operations z3fold_aops;
+static int z3fold_register_migration(struct z3fold_pool *pool)
+{
+ pool->inode = alloc_anon_inode(z3fold_mnt->mnt_sb);
+ if (IS_ERR(pool->inode)) {
+ pool->inode = NULL;
+ return 1;
+ }
+
+ pool->inode->i_mapping->private_data = pool;
+ pool->inode->i_mapping->a_ops = &z3fold_aops;
+ return 0;
+}
+
+static void z3fold_unregister_migration(struct z3fold_pool *pool)
+{
+ if (pool->inode)
+ iput(pool->inode);
+ }
+
+/* Initializes the z3fold header of a newly allocated z3fold page */
+static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
+ struct z3fold_pool *pool, gfp_t gfp)
+{
+ struct z3fold_header *zhdr = page_address(page);
+ struct z3fold_buddy_slots *slots;
+
+ INIT_LIST_HEAD(&page->lru);
+ clear_bit(PAGE_HEADLESS, &page->private);
+ clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
+ clear_bit(NEEDS_COMPACTING, &page->private);
+ clear_bit(PAGE_STALE, &page->private);
+ clear_bit(PAGE_CLAIMED, &page->private);
+ if (headless)
+ return zhdr;
+
+ slots = alloc_slots(pool, gfp);
+ if (!slots)
+ return NULL;
+
+ spin_lock_init(&zhdr->page_lock);
+ kref_init(&zhdr->refcount);
+ zhdr->first_chunks = 0;
+ zhdr->middle_chunks = 0;
+ zhdr->last_chunks = 0;
+ zhdr->first_num = 0;
+ zhdr->start_middle = 0;
+ zhdr->cpu = -1;
+ zhdr->foreign_handles = 0;
+ zhdr->mapped_count = 0;
+ zhdr->slots = slots;
+ zhdr->pool = pool;
+ INIT_LIST_HEAD(&zhdr->buddy);
+ INIT_WORK(&zhdr->work, compact_page_work);
+ return zhdr;
+}
+
+/* Resets the struct page fields and frees the page */
+static void free_z3fold_page(struct page *page, bool headless)
+{
+ if (!headless) {
+ lock_page(page);
+ __ClearPageMovable(page);
+ unlock_page(page);
+ }
+ ClearPagePrivate(page);
+ __free_page(page);
+}
+
+/* Helper function to build the index */
+static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
+{
+ return (bud + zhdr->first_num) & BUDDY_MASK;
+}
+
/*
* Encodes the handle of a particular buddy within a z3fold page
* Pool lock should be held as this function accesses first_num
*/
-static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
+static unsigned long __encode_handle(struct z3fold_header *zhdr,
+ struct z3fold_buddy_slots *slots,
+ enum buddy bud)
{
- unsigned long handle;
+ unsigned long h = (unsigned long)zhdr;
+ int idx = 0;
- handle = (unsigned long)zhdr;
- if (bud != HEADLESS) {
- handle |= (bud + zhdr->first_num) & BUDDY_MASK;
- if (bud == LAST)
- handle |= (zhdr->last_chunks << BUDDY_SHIFT);
- }
- return handle;
+ /*
+ * For a headless page, its handle is its pointer with the extra
+ * PAGE_HEADLESS bit set
+ */
+ if (bud == HEADLESS)
+ return h | (1 << PAGE_HEADLESS);
+
+ /* otherwise, return pointer to encoded handle */
+ idx = __idx(zhdr, bud);
+ h += idx;
+ if (bud == LAST)
+ h |= (zhdr->last_chunks << BUDDY_SHIFT);
+
+ write_lock(&slots->lock);
+ slots->slot[idx] = h;
+ write_unlock(&slots->lock);
+ return (unsigned long)&slots->slot[idx];
}
-/* Returns the z3fold page where a given handle is stored */
-static struct z3fold_header *handle_to_z3fold_header(unsigned long handle)
+static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
{
- return (struct z3fold_header *)(handle & PAGE_MASK);
+ return __encode_handle(zhdr, zhdr->slots, bud);
}
/* only for LAST bud, returns zero otherwise */
static unsigned short handle_to_chunks(unsigned long handle)
{
- return (handle & ~PAGE_MASK) >> BUDDY_SHIFT;
+ struct z3fold_buddy_slots *slots = handle_to_slots(handle);
+ unsigned long addr;
+
+ read_lock(&slots->lock);
+ addr = *(unsigned long *)handle;
+ read_unlock(&slots->lock);
+ return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
}
/*
@@ -251,24 +502,39 @@
*/
static enum buddy handle_to_buddy(unsigned long handle)
{
- struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
- return (handle - zhdr->first_num) & BUDDY_MASK;
+ 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->pool;
+ 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(&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);
@@ -295,9 +561,11 @@
{
struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
refcount);
- spin_lock(&zhdr->pool->lock);
+ struct z3fold_pool *pool = zhdr_to_pool(zhdr);
+
+ spin_lock(&pool->lock);
list_del_init(&zhdr->buddy);
- spin_unlock(&zhdr->pool->lock);
+ spin_unlock(&pool->lock);
WARN_ON(z3fold_page_trylock(zhdr));
__release_z3fold_page(zhdr, true);
@@ -318,7 +586,7 @@
continue;
spin_unlock(&pool->stale_lock);
cancel_work_sync(&zhdr->work);
- free_z3fold_page(page);
+ free_z3fold_page(page, false);
cond_resched();
spin_lock(&pool->stale_lock);
}
@@ -349,6 +617,45 @@
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 = get_cpu_ptr(pool->unbuddied);
+
+ int freechunks = num_free_chunks(zhdr);
+ spin_lock(&pool->lock);
+ list_add(&zhdr->buddy, &unbuddied[freechunks]);
+ spin_unlock(&pool->lock);
+ zhdr->cpu = smp_processor_id();
+ put_cpu_ptr(pool->unbuddied);
+ }
+}
+
+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)
{
@@ -356,6 +663,108 @@
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
@@ -366,6 +775,9 @@
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 */
@@ -406,10 +818,8 @@
static void do_compact_page(struct z3fold_header *zhdr, bool locked)
{
- struct z3fold_pool *pool = zhdr->pool;
+ struct z3fold_pool *pool = zhdr_to_pool(zhdr);
struct page *page;
- struct list_head *unbuddied;
- int fchunks;
page = virt_to_page(zhdr);
if (locked)
@@ -429,19 +839,26 @@
return;
}
- z3fold_compact_page(zhdr);
- unbuddied = get_cpu_ptr(pool->unbuddied);
- fchunks = num_free_chunks(zhdr);
- if (fchunks < NCHUNKS &&
- (!zhdr->first_chunks || !zhdr->middle_chunks ||
- !zhdr->last_chunks)) {
- /* the page's not completely free and it's unbuddied */
- spin_lock(&pool->lock);
- list_add(&zhdr->buddy, &unbuddied[fchunks]);
- spin_unlock(&pool->lock);
- zhdr->cpu = smp_processor_id();
+ if (test_bit(PAGE_STALE, &page->private) ||
+ test_and_set_bit(PAGE_CLAIMED, &page->private)) {
+ z3fold_page_unlock(zhdr);
+ return;
}
- put_cpu_ptr(pool->unbuddied);
+
+ 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);
}
@@ -453,6 +870,108 @@
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:
+ /* First, try to find an unbuddied z3fold page. */
+ unbuddied = get_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;
+ put_cpu_ptr(pool->unbuddied);
+ 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;
+ put_cpu_ptr(pool->unbuddied);
+ 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;
+ }
+ put_cpu_ptr(pool->unbuddied);
+
+ 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
@@ -476,6 +995,11 @@
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, 2);
@@ -497,15 +1021,21 @@
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;
@@ -519,8 +1049,21 @@
*/
static void z3fold_destroy_pool(struct z3fold_pool *pool)
{
- destroy_workqueue(pool->release_wq);
+ 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);
}
@@ -546,13 +1089,13 @@
static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
- int chunks = 0, i, freechunks;
+ 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 || (gfp & __GFP_HIGHMEM))
+ if (!size)
return -EINVAL;
if (size > PAGE_SIZE)
@@ -561,68 +1104,11 @@
if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
bud = HEADLESS;
else {
- struct list_head *unbuddied;
- chunks = size_to_chunks(size);
-
-lookup:
- /* First, try to find an unbuddied z3fold page. */
- unbuddied = get_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);
- put_cpu_ptr(pool->unbuddied);
- 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)) {
- z3fold_page_unlock(zhdr);
- zhdr = NULL;
- put_cpu_ptr(pool->unbuddied);
- 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;
- }
- put_cpu_ptr(pool->unbuddied);
-
+retry:
+ zhdr = __z3fold_alloc(pool, size, can_sleep);
if (zhdr) {
- if (zhdr->first_chunks == 0) {
- if (zhdr->middle_chunks != 0 &&
- chunks >= zhdr->start_middle)
- bud = LAST;
- else
- bud = FIRST;
- } else if (zhdr->last_chunks == 0)
- bud = LAST;
- else if (zhdr->middle_chunks == 0)
- bud = MIDDLE;
- else {
+ bud = get_free_buddy(zhdr, chunks);
+ if (bud == HEADLESS) {
if (kref_put(&zhdr->refcount,
release_z3fold_page_locked))
atomic64_dec(&pool->pages_nr);
@@ -630,8 +1116,9 @@
z3fold_page_unlock(zhdr);
pr_err("No free chunks in unbuddied\n");
WARN_ON(1);
- goto lookup;
+ goto retry;
}
+ page = virt_to_page(zhdr);
goto found;
}
bud = FIRST;
@@ -662,12 +1149,26 @@
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);
- zhdr = init_z3fold_page(page, pool);
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);
@@ -680,19 +1181,7 @@
zhdr->middle_chunks = chunks;
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
}
-
- if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
- zhdr->middle_chunks == 0) {
- struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied);
-
- /* Add to unbuddied list */
- freechunks = num_free_chunks(zhdr);
- spin_lock(&pool->lock);
- list_add(&zhdr->buddy, &unbuddied[freechunks]);
- spin_unlock(&pool->lock);
- zhdr->cpu = smp_processor_id();
- put_cpu_ptr(pool->unbuddied);
- }
+ add_to_unbuddied(pool, zhdr);
headless:
spin_lock(&pool->lock);
@@ -725,9 +1214,11 @@
struct z3fold_header *zhdr;
struct page *page;
enum buddy bud;
+ bool page_claimed;
- zhdr = handle_to_z3fold_header(handle);
+ 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.
@@ -735,18 +1226,18 @@
* has not been set before, we release this page
* immediately so we don't care about its value any more.
*/
- if (!test_and_set_bit(PAGE_CLAIMED, &page->private)) {
+ if (!page_claimed) {
spin_lock(&pool->lock);
list_del(&page->lru);
spin_unlock(&pool->lock);
- free_z3fold_page(page);
+ put_z3fold_header(zhdr);
+ free_z3fold_page(page, true);
atomic64_dec(&pool->pages_nr);
}
return;
}
/* Non-headless case */
- z3fold_page_lock(zhdr);
bud = handle_to_buddy(handle);
switch (bud) {
@@ -762,20 +1253,24 @@
default:
pr_err("%s: unknown bud %d\n", __func__, bud);
WARN_ON(1);
- z3fold_page_unlock(zhdr);
+ 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 (test_bit(PAGE_CLAIMED, &page->private)) {
+ 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)) {
- z3fold_page_unlock(zhdr);
+ put_z3fold_header(zhdr);
+ clear_bit(PAGE_CLAIMED, &page->private);
return;
}
if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
@@ -784,12 +1279,14 @@
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);
- z3fold_page_unlock(zhdr);
+ put_z3fold_header(zhdr);
}
/**
@@ -830,11 +1327,15 @@
*/
static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
{
- int i, ret = 0;
+ 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) {
@@ -849,21 +1350,50 @@
list_for_each_prev(pos, &pool->lru) {
page = list_entry(pos, struct page, lru);
- /* this bit could have been set by free, in which case
- * we pass over to the next page in the pool.
- */
- if (test_and_set_bit(PAGE_CLAIMED, &page->private))
- continue;
-
zhdr = page_address(page);
- if (test_bit(PAGE_HEADLESS, &page->private))
- break;
+ 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 */
}
- kref_get(&zhdr->refcount);
+
+ /* 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;
@@ -877,19 +1407,24 @@
if (!test_bit(PAGE_HEADLESS, &page->private)) {
/*
- * We need encode the handles before unlocking, since
- * we can race with free that will set
- * (first|last)_chunks to 0
+ * 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, FIRST);
+ first_handle = __encode_handle(zhdr, &slots,
+ FIRST);
if (zhdr->middle_chunks)
- middle_handle = encode_handle(zhdr, MIDDLE);
+ middle_handle = __encode_handle(zhdr, &slots,
+ MIDDLE);
if (zhdr->last_chunks)
- last_handle = encode_handle(zhdr, LAST);
+ last_handle = __encode_handle(zhdr, &slots,
+ LAST);
/*
* it's safe to unlock here because we hold a
* reference to this page
@@ -899,7 +1434,6 @@
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);
@@ -919,18 +1453,20 @@
next:
if (test_bit(PAGE_HEADLESS, &page->private)) {
if (ret == 0) {
- free_z3fold_page(page);
+ 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);
- } else {
- z3fold_page_lock(zhdr);
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;
}
@@ -943,6 +1479,7 @@
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 */
@@ -969,14 +1506,13 @@
void *addr;
enum buddy buddy;
- zhdr = handle_to_z3fold_header(handle);
+ zhdr = get_z3fold_header(handle);
addr = zhdr;
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
goto out;
- z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
switch (buddy) {
case FIRST:
@@ -996,8 +1532,10 @@
break;
}
- z3fold_page_unlock(zhdr);
+ if (addr)
+ zhdr->mapped_count++;
out:
+ put_z3fold_header(zhdr);
return addr;
}
@@ -1012,17 +1550,17 @@
struct page *page;
enum buddy buddy;
- zhdr = handle_to_z3fold_header(handle);
+ zhdr = get_z3fold_header(handle);
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
return;
- z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
if (buddy == MIDDLE)
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
- z3fold_page_unlock(zhdr);
+ zhdr->mapped_count--;
+ put_z3fold_header(zhdr);
}
/**
@@ -1035,6 +1573,140 @@
{
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
@@ -1133,8 +1805,14 @@
static int __init init_z3fold(void)
{
+ int ret;
+
/* Make sure the z3fold header is not larger than the page size */
BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
+ ret = z3fold_mount();
+ if (ret)
+ return ret;
+
zpool_register_driver(&z3fold_zpool_driver);
return 0;
@@ -1142,6 +1820,7 @@
static void __exit exit_z3fold(void)
{
+ z3fold_unmount();
zpool_unregister_driver(&z3fold_zpool_driver);
}
--
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