#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/atomic.h>
+#include <linux/sched.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/percpu.h>
#include <linux/preempt.h>
+#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/zpool.h>
};
/*
- * struct z3fold_header - z3fold page metadata occupying the first chunk of each
+ * 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
+ * @buddy: links the z3fold page into the relevant list in the
+ * pool
* @page_lock: per-page lock
- * @refcount: reference cound for the z3fold page
+ * @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
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;
/**
* struct z3fold_pool - stores metadata for each z3fold pool
- * @lock: protects all pool fields and first|last_chunk fields of any
- * z3fold page in the pool
- * @unbuddied: array of lists tracking z3fold pages that contain 2- buddies;
- * the lists each z3fold page is added to depends on the size of
- * its free region.
+ * @name: pool name
+ * @lock: protects pool unbuddied/lru lists
+ * @stale_lock: protects pool stale page list
+ * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
+ * buddies; the list each z3fold page is added to depends on
+ * the size of its free region.
* @lru: list tracking the z3fold pages in LRU order by most recently
* added buddy.
+ * @stale: list of pages marked for freeing
* @pages_nr: number of z3fold pages in the pool.
* @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
*
* This structure is allocated at pool creation time and maintains metadata
* pertaining to a particular z3fold pool.
*/
struct z3fold_pool {
+ const char *name;
spinlock_t lock;
- struct list_head unbuddied[NCHUNKS];
+ spinlock_t stale_lock;
+ struct list_head *unbuddied;
struct list_head lru;
+ struct list_head stale;
atomic64_t pages_nr;
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;
};
/*
enum z3fold_page_flags {
PAGE_HEADLESS = 0,
MIDDLE_CHUNK_MAPPED,
+ NEEDS_COMPACTING,
+ PAGE_STALE
};
-
/*****************
* Helpers
*****************/
#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)
+static struct z3fold_header *init_z3fold_page(struct page *page,
+ struct z3fold_pool *pool)
{
struct z3fold_header *zhdr = page_address(page);
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);
spin_lock_init(&zhdr->page_lock);
kref_init(&zhdr->refcount);
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;
}
__free_page(page);
}
-static void release_z3fold_page(struct kref *ref)
-{
- struct z3fold_header *zhdr;
- struct page *page;
-
- zhdr = container_of(ref, struct z3fold_header, refcount);
- page = virt_to_page(zhdr);
-
- if (!list_empty(&zhdr->buddy))
- list_del(&zhdr->buddy);
- if (!list_empty(&page->lru))
- list_del(&page->lru);
- free_z3fold_page(page);
-}
-
/* Lock a z3fold page */
static inline void z3fold_page_lock(struct z3fold_header *zhdr)
{
return (handle - zhdr->first_num) & BUDDY_MASK;
}
+static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
+{
+ struct page *page = virt_to_page(zhdr);
+ struct z3fold_pool *pool = zhdr->pool;
+
+ WARN_ON(!list_empty(&zhdr->buddy));
+ set_bit(PAGE_STALE, &page->private);
+ spin_lock(&pool->lock);
+ if (!list_empty(&page->lru))
+ list_del(&page->lru);
+ spin_unlock(&pool->lock);
+ if (locked)
+ z3fold_page_unlock(zhdr);
+ spin_lock(&pool->stale_lock);
+ list_add(&zhdr->buddy, &pool->stale);
+ queue_work(pool->release_wq, &pool->work);
+ spin_unlock(&pool->stale_lock);
+}
+
+static void __attribute__((__unused__))
+ release_z3fold_page(struct kref *ref)
+{
+ struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
+ refcount);
+ __release_z3fold_page(zhdr, false);
+}
+
+static void release_z3fold_page_locked(struct kref *ref)
+{
+ struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
+ refcount);
+ WARN_ON(z3fold_page_trylock(zhdr));
+ __release_z3fold_page(zhdr, true);
+}
+
+static void release_z3fold_page_locked_list(struct kref *ref)
+{
+ struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
+ refcount);
+ spin_lock(&zhdr->pool->lock);
+ list_del_init(&zhdr->buddy);
+ spin_unlock(&zhdr->pool->lock);
+
+ WARN_ON(z3fold_page_trylock(zhdr));
+ __release_z3fold_page(zhdr, true);
+}
+
+static void free_pages_work(struct work_struct *w)
+{
+ struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
+
+ spin_lock(&pool->stale_lock);
+ while (!list_empty(&pool->stale)) {
+ struct z3fold_header *zhdr = list_first_entry(&pool->stale,
+ struct z3fold_header, buddy);
+ struct page *page = virt_to_page(zhdr);
+
+ list_del(&zhdr->buddy);
+ if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
+ continue;
+ clear_bit(NEEDS_COMPACTING, &page->private);
+ spin_unlock(&pool->stale_lock);
+ cancel_work_sync(&zhdr->work);
+ free_z3fold_page(page);
+ 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.
return nfree;
}
-/*****************
- * API Functions
-*****************/
-/**
- * z3fold_create_pool() - create a new z3fold pool
- * @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(gfp_t gfp,
- const struct z3fold_ops *ops)
-{
- struct z3fold_pool *pool;
- int i;
-
- pool = kzalloc(sizeof(struct z3fold_pool), gfp);
- if (!pool)
- return NULL;
- spin_lock_init(&pool->lock);
- for_each_unbuddied_list(i, 0)
- INIT_LIST_HEAD(&pool->unbuddied[i]);
- INIT_LIST_HEAD(&pool->lru);
- atomic64_set(&pool->pages_nr, 0);
- pool->ops = ops;
- return pool;
-}
-
-/**
- * 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)
-{
- kfree(pool);
-}
-
static inline void *mchunk_memmove(struct z3fold_header *zhdr,
unsigned short dst_chunk)
{
return 0;
}
+static void do_compact_page(struct z3fold_header *zhdr, bool locked)
+{
+ struct z3fold_pool *pool = zhdr->pool;
+ struct page *page;
+ struct list_head *unbuddied;
+ int fchunks;
+
+ page = virt_to_page(zhdr);
+ if (locked)
+ WARN_ON(z3fold_page_trylock(zhdr));
+ else
+ z3fold_page_lock(zhdr);
+ if (test_bit(PAGE_STALE, &page->private) ||
+ !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);
+
+ 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();
+ }
+ put_cpu_ptr(pool->unbuddied);
+ 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);
+}
+
+
+/*
+ * 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;
+ spin_lock_init(&pool->lock);
+ spin_lock_init(&pool->stale_lock);
+ pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2);
+ 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;
+ pool->release_wq = create_singlethread_workqueue(pool->name);
+ if (!pool->release_wq)
+ goto out_wq;
+ INIT_WORK(&pool->work, free_pages_work);
+ pool->ops = ops;
+ return pool;
+
+out_wq:
+ destroy_workqueue(pool->compact_wq);
+out:
+ kfree(pool);
+ 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)
+{
+ destroy_workqueue(pool->release_wq);
+ destroy_workqueue(pool->compact_wq);
+ kfree(pool);
+}
+
/**
* z3fold_alloc() - allocates a region of a given size
* @pool: z3fold pool from which to allocate
{
int chunks = 0, i, freechunks;
struct z3fold_header *zhdr = NULL;
+ struct page *page = NULL;
enum buddy bud;
- struct page *page;
+ bool can_sleep = (gfp & __GFP_RECLAIM) == __GFP_RECLAIM;
if (!size || (gfp & __GFP_HIGHMEM))
return -EINVAL;
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. */
- zhdr = NULL;
+ unbuddied = get_cpu_ptr(pool->unbuddied);
for_each_unbuddied_list(i, chunks) {
- spin_lock(&pool->lock);
- zhdr = list_first_entry_or_null(&pool->unbuddied[i],
+ struct list_head *l = &unbuddied[i];
+
+ zhdr = list_first_entry_or_null(READ_ONCE(l),
struct z3fold_header, buddy);
- if (!zhdr || !z3fold_page_trylock(zhdr)) {
- spin_unlock(&pool->lock);
+
+ 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;
}
- kref_get(&zhdr->refcount);
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);
+
+ if (zhdr) {
if (zhdr->first_chunks == 0) {
if (zhdr->middle_chunks != 0 &&
chunks >= zhdr->start_middle)
else if (zhdr->middle_chunks == 0)
bud = MIDDLE;
else {
- z3fold_page_unlock(zhdr);
- spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount,
- release_z3fold_page))
+ release_z3fold_page_locked))
atomic64_dec(&pool->pages_nr);
- spin_unlock(&pool->lock);
+ else
+ z3fold_page_unlock(zhdr);
pr_err("No free chunks in unbuddied\n");
WARN_ON(1);
- continue;
+ goto lookup;
}
goto found;
}
bud = FIRST;
}
- /* Couldn't find unbuddied z3fold page, create new one */
- page = alloc_page(gfp);
+ 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 must make
+ * sure it won't be called in case we're in atomic context.
+ */
+ if (zhdr && (can_sleep || !work_pending(&zhdr->work) ||
+ !unlikely(work_busy(&zhdr->work)))) {
+ list_del(&zhdr->buddy);
+ clear_bit(NEEDS_COMPACTING, &page->private);
+ spin_unlock(&pool->stale_lock);
+ if (can_sleep)
+ cancel_work_sync(&zhdr->work);
+ page = virt_to_page(zhdr);
+ } else {
+ spin_unlock(&pool->stale_lock);
+ page = alloc_page(gfp);
+ }
+
if (!page)
return -ENOMEM;
atomic64_inc(&pool->pages_nr);
- zhdr = init_z3fold_page(page);
+ zhdr = init_z3fold_page(page, pool);
if (bud == HEADLESS) {
set_bit(PAGE_HEADLESS, &page->private);
- spin_lock(&pool->lock);
goto headless;
}
z3fold_page_lock(zhdr);
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
}
- spin_lock(&pool->lock);
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);
- list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+ spin_lock(&pool->lock);
+ list_add(&zhdr->buddy, &unbuddied[freechunks]);
+ spin_unlock(&pool->lock);
+ zhdr->cpu = smp_processor_id();
+ put_cpu_ptr(pool->unbuddied);
}
headless:
+ spin_lock(&pool->lock);
/* Add/move z3fold page to beginning of LRU */
if (!list_empty(&page->lru))
list_del(&page->lru);
static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
- int freechunks;
struct page *page;
enum buddy bud;
spin_unlock(&pool->lock);
free_z3fold_page(page);
atomic64_dec(&pool->pages_nr);
- } else {
- if (zhdr->first_chunks != 0 || zhdr->middle_chunks != 0 ||
- zhdr->last_chunks != 0) {
- z3fold_compact_page(zhdr);
- /* Add to the unbuddied list */
- spin_lock(&pool->lock);
- if (!list_empty(&zhdr->buddy))
- list_del(&zhdr->buddy);
- freechunks = num_free_chunks(zhdr);
- list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
- spin_unlock(&pool->lock);
- }
+ return;
+ }
+
+ if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
+ atomic64_dec(&pool->pages_nr);
+ return;
+ }
+ if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
z3fold_page_unlock(zhdr);
+ return;
+ }
+ if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
spin_lock(&pool->lock);
- if (kref_put(&zhdr->refcount, release_z3fold_page))
- atomic64_dec(&pool->pages_nr);
+ list_del_init(&zhdr->buddy);
spin_unlock(&pool->lock);
+ zhdr->cpu = -1;
+ do_compact_page(zhdr, true);
+ return;
}
-
+ queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
+ z3fold_page_unlock(zhdr);
}
/**
*/
static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
{
- int i, ret = 0, freechunks;
- struct z3fold_header *zhdr;
- struct page *page;
+ int i, ret = 0;
+ struct z3fold_header *zhdr = NULL;
+ struct page *page = NULL;
+ struct list_head *pos;
unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
spin_lock(&pool->lock);
spin_unlock(&pool->lock);
return -EINVAL;
}
- page = list_last_entry(&pool->lru, struct page, lru);
+ list_for_each_prev(pos, &pool->lru) {
+ page = list_entry(pos, struct page, lru);
+ if (test_bit(PAGE_HEADLESS, &page->private))
+ /* candidate found */
+ break;
+
+ zhdr = page_address(page);
+ if (!z3fold_page_trylock(zhdr))
+ continue; /* can't evict at this point */
+ kref_get(&zhdr->refcount);
+ list_del_init(&zhdr->buddy);
+ zhdr->cpu = -1;
+ }
+
list_del_init(&page->lru);
+ spin_unlock(&pool->lock);
- zhdr = page_address(page);
if (!test_bit(PAGE_HEADLESS, &page->private)) {
- if (!list_empty(&zhdr->buddy))
- list_del_init(&zhdr->buddy);
- kref_get(&zhdr->refcount);
- spin_unlock(&pool->lock);
- z3fold_page_lock(zhdr);
/*
* We need encode the handles before unlocking, since
* we can race with free that will set
middle_handle = encode_handle(zhdr, MIDDLE);
if (zhdr->last_chunks)
last_handle = encode_handle(zhdr, 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;
- spin_unlock(&pool->lock);
}
/* Issue the eviction callback(s) */
if (ret == 0) {
free_z3fold_page(page);
return 0;
- } else {
- spin_lock(&pool->lock);
- }
- } else {
- z3fold_page_lock(zhdr);
- if ((zhdr->first_chunks || zhdr->last_chunks ||
- zhdr->middle_chunks) &&
- !(zhdr->first_chunks && zhdr->last_chunks &&
- zhdr->middle_chunks)) {
- z3fold_compact_page(zhdr);
- /* add to unbuddied list */
- spin_lock(&pool->lock);
- freechunks = num_free_chunks(zhdr);
- list_add(&zhdr->buddy,
- &pool->unbuddied[freechunks]);
- spin_unlock(&pool->lock);
- }
- z3fold_page_unlock(zhdr);
- spin_lock(&pool->lock);
- if (kref_put(&zhdr->refcount, release_z3fold_page)) {
- spin_unlock(&pool->lock);
- atomic64_dec(&pool->pages_nr);
- return 0;
}
+ } else if (kref_put(&zhdr->refcount, release_z3fold_page)) {
+ atomic64_dec(&pool->pages_nr);
+ return 0;
}
+ spin_lock(&pool->lock);
/*
* Add to the beginning of LRU.
{
struct z3fold_pool *pool;
- pool = z3fold_create_pool(gfp, zpool_ops ? &z3fold_zpool_ops : NULL);
+ pool = z3fold_create_pool(name, gfp,
+ zpool_ops ? &z3fold_zpool_ops : NULL);
if (pool) {
pool->zpool = zpool;
pool->zpool_ops = zpool_ops;
git.samba.org / sfrench / cifs-2.6.git / blobdiff