mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 03:10:12 +00:00
![Mikulas Patocka](/assets/img/avatar_default.png)
In the past, the function __vmalloc didn't respect the GFP flags - it allocated memory with the provided gfp flags, but it allocated page tables with GFP_KERNEL. This was fixed in commit451769ebb7
("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc") so the memalloc_noio_{save,restore} workaround is no longer needed. The function kvmalloc didn't like flags different from GFP_KERNEL. This was fixed in commita421ef3030
("mm: allow !GFP_KERNEL allocations for kvmalloc"), so kvmalloc can now be called with GFP_NOIO. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
2930 lines
68 KiB
C
2930 lines
68 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Copyright (C) 2009-2011 Red Hat, Inc.
|
|
*
|
|
* Author: Mikulas Patocka <mpatocka@redhat.com>
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#include <linux/dm-bufio.h>
|
|
|
|
#include <linux/device-mapper.h>
|
|
#include <linux/dm-io.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/vmalloc.h>
|
|
#include <linux/shrinker.h>
|
|
#include <linux/module.h>
|
|
#include <linux/rbtree.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <linux/jump_label.h>
|
|
|
|
#include "dm.h"
|
|
|
|
#define DM_MSG_PREFIX "bufio"
|
|
|
|
/*
|
|
* Memory management policy:
|
|
* Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
|
|
* or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
|
|
* Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
|
|
* Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
|
|
* dirty buffers.
|
|
*/
|
|
#define DM_BUFIO_MIN_BUFFERS 8
|
|
|
|
#define DM_BUFIO_MEMORY_PERCENT 2
|
|
#define DM_BUFIO_VMALLOC_PERCENT 25
|
|
#define DM_BUFIO_WRITEBACK_RATIO 3
|
|
#define DM_BUFIO_LOW_WATERMARK_RATIO 16
|
|
|
|
/*
|
|
* Check buffer ages in this interval (seconds)
|
|
*/
|
|
#define DM_BUFIO_WORK_TIMER_SECS 30
|
|
|
|
/*
|
|
* Free buffers when they are older than this (seconds)
|
|
*/
|
|
#define DM_BUFIO_DEFAULT_AGE_SECS 300
|
|
|
|
/*
|
|
* The nr of bytes of cached data to keep around.
|
|
*/
|
|
#define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024)
|
|
|
|
/*
|
|
* Align buffer writes to this boundary.
|
|
* Tests show that SSDs have the highest IOPS when using 4k writes.
|
|
*/
|
|
#define DM_BUFIO_WRITE_ALIGN 4096
|
|
|
|
/*
|
|
* dm_buffer->list_mode
|
|
*/
|
|
#define LIST_CLEAN 0
|
|
#define LIST_DIRTY 1
|
|
#define LIST_SIZE 2
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Rather than use an LRU list, we use a clock algorithm where entries
|
|
* are held in a circular list. When an entry is 'hit' a reference bit
|
|
* is set. The least recently used entry is approximated by running a
|
|
* cursor around the list selecting unreferenced entries. Referenced
|
|
* entries have their reference bit cleared as the cursor passes them.
|
|
*/
|
|
struct lru_entry {
|
|
struct list_head list;
|
|
atomic_t referenced;
|
|
};
|
|
|
|
struct lru_iter {
|
|
struct lru *lru;
|
|
struct list_head list;
|
|
struct lru_entry *stop;
|
|
struct lru_entry *e;
|
|
};
|
|
|
|
struct lru {
|
|
struct list_head *cursor;
|
|
unsigned long count;
|
|
|
|
struct list_head iterators;
|
|
};
|
|
|
|
/*--------------*/
|
|
|
|
static void lru_init(struct lru *lru)
|
|
{
|
|
lru->cursor = NULL;
|
|
lru->count = 0;
|
|
INIT_LIST_HEAD(&lru->iterators);
|
|
}
|
|
|
|
static void lru_destroy(struct lru *lru)
|
|
{
|
|
WARN_ON_ONCE(lru->cursor);
|
|
WARN_ON_ONCE(!list_empty(&lru->iterators));
|
|
}
|
|
|
|
/*
|
|
* Insert a new entry into the lru.
|
|
*/
|
|
static void lru_insert(struct lru *lru, struct lru_entry *le)
|
|
{
|
|
/*
|
|
* Don't be tempted to set to 1, makes the lru aspect
|
|
* perform poorly.
|
|
*/
|
|
atomic_set(&le->referenced, 0);
|
|
|
|
if (lru->cursor) {
|
|
list_add_tail(&le->list, lru->cursor);
|
|
} else {
|
|
INIT_LIST_HEAD(&le->list);
|
|
lru->cursor = &le->list;
|
|
}
|
|
lru->count++;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Convert a list_head pointer to an lru_entry pointer.
|
|
*/
|
|
static inline struct lru_entry *to_le(struct list_head *l)
|
|
{
|
|
return container_of(l, struct lru_entry, list);
|
|
}
|
|
|
|
/*
|
|
* Initialize an lru_iter and add it to the list of cursors in the lru.
|
|
*/
|
|
static void lru_iter_begin(struct lru *lru, struct lru_iter *it)
|
|
{
|
|
it->lru = lru;
|
|
it->stop = lru->cursor ? to_le(lru->cursor->prev) : NULL;
|
|
it->e = lru->cursor ? to_le(lru->cursor) : NULL;
|
|
list_add(&it->list, &lru->iterators);
|
|
}
|
|
|
|
/*
|
|
* Remove an lru_iter from the list of cursors in the lru.
|
|
*/
|
|
static inline void lru_iter_end(struct lru_iter *it)
|
|
{
|
|
list_del(&it->list);
|
|
}
|
|
|
|
/* Predicate function type to be used with lru_iter_next */
|
|
typedef bool (*iter_predicate)(struct lru_entry *le, void *context);
|
|
|
|
/*
|
|
* Advance the cursor to the next entry that passes the
|
|
* predicate, and return that entry. Returns NULL if the
|
|
* iteration is complete.
|
|
*/
|
|
static struct lru_entry *lru_iter_next(struct lru_iter *it,
|
|
iter_predicate pred, void *context)
|
|
{
|
|
struct lru_entry *e;
|
|
|
|
while (it->e) {
|
|
e = it->e;
|
|
|
|
/* advance the cursor */
|
|
if (it->e == it->stop)
|
|
it->e = NULL;
|
|
else
|
|
it->e = to_le(it->e->list.next);
|
|
|
|
if (pred(e, context))
|
|
return e;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Invalidate a specific lru_entry and update all cursors in
|
|
* the lru accordingly.
|
|
*/
|
|
static void lru_iter_invalidate(struct lru *lru, struct lru_entry *e)
|
|
{
|
|
struct lru_iter *it;
|
|
|
|
list_for_each_entry(it, &lru->iterators, list) {
|
|
/* Move c->e forwards if necc. */
|
|
if (it->e == e) {
|
|
it->e = to_le(it->e->list.next);
|
|
if (it->e == e)
|
|
it->e = NULL;
|
|
}
|
|
|
|
/* Move it->stop backwards if necc. */
|
|
if (it->stop == e) {
|
|
it->stop = to_le(it->stop->list.prev);
|
|
if (it->stop == e)
|
|
it->stop = NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Remove a specific entry from the lru.
|
|
*/
|
|
static void lru_remove(struct lru *lru, struct lru_entry *le)
|
|
{
|
|
lru_iter_invalidate(lru, le);
|
|
if (lru->count == 1) {
|
|
lru->cursor = NULL;
|
|
} else {
|
|
if (lru->cursor == &le->list)
|
|
lru->cursor = lru->cursor->next;
|
|
list_del(&le->list);
|
|
}
|
|
lru->count--;
|
|
}
|
|
|
|
/*
|
|
* Mark as referenced.
|
|
*/
|
|
static inline void lru_reference(struct lru_entry *le)
|
|
{
|
|
atomic_set(&le->referenced, 1);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Remove the least recently used entry (approx), that passes the predicate.
|
|
* Returns NULL on failure.
|
|
*/
|
|
enum evict_result {
|
|
ER_EVICT,
|
|
ER_DONT_EVICT,
|
|
ER_STOP, /* stop looking for something to evict */
|
|
};
|
|
|
|
typedef enum evict_result (*le_predicate)(struct lru_entry *le, void *context);
|
|
|
|
static struct lru_entry *lru_evict(struct lru *lru, le_predicate pred, void *context)
|
|
{
|
|
unsigned long tested = 0;
|
|
struct list_head *h = lru->cursor;
|
|
struct lru_entry *le;
|
|
|
|
if (!h)
|
|
return NULL;
|
|
/*
|
|
* In the worst case we have to loop around twice. Once to clear
|
|
* the reference flags, and then again to discover the predicate
|
|
* fails for all entries.
|
|
*/
|
|
while (tested < lru->count) {
|
|
le = container_of(h, struct lru_entry, list);
|
|
|
|
if (atomic_read(&le->referenced)) {
|
|
atomic_set(&le->referenced, 0);
|
|
} else {
|
|
tested++;
|
|
switch (pred(le, context)) {
|
|
case ER_EVICT:
|
|
/*
|
|
* Adjust the cursor, so we start the next
|
|
* search from here.
|
|
*/
|
|
lru->cursor = le->list.next;
|
|
lru_remove(lru, le);
|
|
return le;
|
|
|
|
case ER_DONT_EVICT:
|
|
break;
|
|
|
|
case ER_STOP:
|
|
lru->cursor = le->list.next;
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
h = h->next;
|
|
|
|
cond_resched();
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Buffer state bits.
|
|
*/
|
|
#define B_READING 0
|
|
#define B_WRITING 1
|
|
#define B_DIRTY 2
|
|
|
|
/*
|
|
* Describes how the block was allocated:
|
|
* kmem_cache_alloc(), __get_free_pages() or vmalloc().
|
|
* See the comment at alloc_buffer_data.
|
|
*/
|
|
enum data_mode {
|
|
DATA_MODE_SLAB = 0,
|
|
DATA_MODE_GET_FREE_PAGES = 1,
|
|
DATA_MODE_VMALLOC = 2,
|
|
DATA_MODE_LIMIT = 3
|
|
};
|
|
|
|
struct dm_buffer {
|
|
/* protected by the locks in dm_buffer_cache */
|
|
struct rb_node node;
|
|
|
|
/* immutable, so don't need protecting */
|
|
sector_t block;
|
|
void *data;
|
|
unsigned char data_mode; /* DATA_MODE_* */
|
|
|
|
/*
|
|
* These two fields are used in isolation, so do not need
|
|
* a surrounding lock.
|
|
*/
|
|
atomic_t hold_count;
|
|
unsigned long last_accessed;
|
|
|
|
/*
|
|
* Everything else is protected by the mutex in
|
|
* dm_bufio_client
|
|
*/
|
|
unsigned long state;
|
|
struct lru_entry lru;
|
|
unsigned char list_mode; /* LIST_* */
|
|
blk_status_t read_error;
|
|
blk_status_t write_error;
|
|
unsigned int dirty_start;
|
|
unsigned int dirty_end;
|
|
unsigned int write_start;
|
|
unsigned int write_end;
|
|
struct list_head write_list;
|
|
struct dm_bufio_client *c;
|
|
void (*end_io)(struct dm_buffer *b, blk_status_t bs);
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
#define MAX_STACK 10
|
|
unsigned int stack_len;
|
|
unsigned long stack_entries[MAX_STACK];
|
|
#endif
|
|
};
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
/*
|
|
* The buffer cache manages buffers, particularly:
|
|
* - inc/dec of holder count
|
|
* - setting the last_accessed field
|
|
* - maintains clean/dirty state along with lru
|
|
* - selecting buffers that match predicates
|
|
*
|
|
* It does *not* handle:
|
|
* - allocation/freeing of buffers.
|
|
* - IO
|
|
* - Eviction or cache sizing.
|
|
*
|
|
* cache_get() and cache_put() are threadsafe, you do not need to
|
|
* protect these calls with a surrounding mutex. All the other
|
|
* methods are not threadsafe; they do use locking primitives, but
|
|
* only enough to ensure get/put are threadsafe.
|
|
*/
|
|
|
|
struct buffer_tree {
|
|
struct rw_semaphore lock;
|
|
struct rb_root root;
|
|
} ____cacheline_aligned_in_smp;
|
|
|
|
struct dm_buffer_cache {
|
|
struct lru lru[LIST_SIZE];
|
|
/*
|
|
* We spread entries across multiple trees to reduce contention
|
|
* on the locks.
|
|
*/
|
|
unsigned int num_locks;
|
|
struct buffer_tree trees[];
|
|
};
|
|
|
|
static inline unsigned int cache_index(sector_t block, unsigned int num_locks)
|
|
{
|
|
return dm_hash_locks_index(block, num_locks);
|
|
}
|
|
|
|
static inline void cache_read_lock(struct dm_buffer_cache *bc, sector_t block)
|
|
{
|
|
down_read(&bc->trees[cache_index(block, bc->num_locks)].lock);
|
|
}
|
|
|
|
static inline void cache_read_unlock(struct dm_buffer_cache *bc, sector_t block)
|
|
{
|
|
up_read(&bc->trees[cache_index(block, bc->num_locks)].lock);
|
|
}
|
|
|
|
static inline void cache_write_lock(struct dm_buffer_cache *bc, sector_t block)
|
|
{
|
|
down_write(&bc->trees[cache_index(block, bc->num_locks)].lock);
|
|
}
|
|
|
|
static inline void cache_write_unlock(struct dm_buffer_cache *bc, sector_t block)
|
|
{
|
|
up_write(&bc->trees[cache_index(block, bc->num_locks)].lock);
|
|
}
|
|
|
|
/*
|
|
* Sometimes we want to repeatedly get and drop locks as part of an iteration.
|
|
* This struct helps avoid redundant drop and gets of the same lock.
|
|
*/
|
|
struct lock_history {
|
|
struct dm_buffer_cache *cache;
|
|
bool write;
|
|
unsigned int previous;
|
|
unsigned int no_previous;
|
|
};
|
|
|
|
static void lh_init(struct lock_history *lh, struct dm_buffer_cache *cache, bool write)
|
|
{
|
|
lh->cache = cache;
|
|
lh->write = write;
|
|
lh->no_previous = cache->num_locks;
|
|
lh->previous = lh->no_previous;
|
|
}
|
|
|
|
static void __lh_lock(struct lock_history *lh, unsigned int index)
|
|
{
|
|
if (lh->write)
|
|
down_write(&lh->cache->trees[index].lock);
|
|
else
|
|
down_read(&lh->cache->trees[index].lock);
|
|
}
|
|
|
|
static void __lh_unlock(struct lock_history *lh, unsigned int index)
|
|
{
|
|
if (lh->write)
|
|
up_write(&lh->cache->trees[index].lock);
|
|
else
|
|
up_read(&lh->cache->trees[index].lock);
|
|
}
|
|
|
|
/*
|
|
* Make sure you call this since it will unlock the final lock.
|
|
*/
|
|
static void lh_exit(struct lock_history *lh)
|
|
{
|
|
if (lh->previous != lh->no_previous) {
|
|
__lh_unlock(lh, lh->previous);
|
|
lh->previous = lh->no_previous;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Named 'next' because there is no corresponding
|
|
* 'up/unlock' call since it's done automatically.
|
|
*/
|
|
static void lh_next(struct lock_history *lh, sector_t b)
|
|
{
|
|
unsigned int index = cache_index(b, lh->no_previous); /* no_previous is num_locks */
|
|
|
|
if (lh->previous != lh->no_previous) {
|
|
if (lh->previous != index) {
|
|
__lh_unlock(lh, lh->previous);
|
|
__lh_lock(lh, index);
|
|
lh->previous = index;
|
|
}
|
|
} else {
|
|
__lh_lock(lh, index);
|
|
lh->previous = index;
|
|
}
|
|
}
|
|
|
|
static inline struct dm_buffer *le_to_buffer(struct lru_entry *le)
|
|
{
|
|
return container_of(le, struct dm_buffer, lru);
|
|
}
|
|
|
|
static struct dm_buffer *list_to_buffer(struct list_head *l)
|
|
{
|
|
struct lru_entry *le = list_entry(l, struct lru_entry, list);
|
|
|
|
if (!le)
|
|
return NULL;
|
|
|
|
return le_to_buffer(le);
|
|
}
|
|
|
|
static void cache_init(struct dm_buffer_cache *bc, unsigned int num_locks)
|
|
{
|
|
unsigned int i;
|
|
|
|
bc->num_locks = num_locks;
|
|
|
|
for (i = 0; i < bc->num_locks; i++) {
|
|
init_rwsem(&bc->trees[i].lock);
|
|
bc->trees[i].root = RB_ROOT;
|
|
}
|
|
|
|
lru_init(&bc->lru[LIST_CLEAN]);
|
|
lru_init(&bc->lru[LIST_DIRTY]);
|
|
}
|
|
|
|
static void cache_destroy(struct dm_buffer_cache *bc)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < bc->num_locks; i++)
|
|
WARN_ON_ONCE(!RB_EMPTY_ROOT(&bc->trees[i].root));
|
|
|
|
lru_destroy(&bc->lru[LIST_CLEAN]);
|
|
lru_destroy(&bc->lru[LIST_DIRTY]);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* not threadsafe, or racey depending how you look at it
|
|
*/
|
|
static inline unsigned long cache_count(struct dm_buffer_cache *bc, int list_mode)
|
|
{
|
|
return bc->lru[list_mode].count;
|
|
}
|
|
|
|
static inline unsigned long cache_total(struct dm_buffer_cache *bc)
|
|
{
|
|
return cache_count(bc, LIST_CLEAN) + cache_count(bc, LIST_DIRTY);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Gets a specific buffer, indexed by block.
|
|
* If the buffer is found then its holder count will be incremented and
|
|
* lru_reference will be called.
|
|
*
|
|
* threadsafe
|
|
*/
|
|
static struct dm_buffer *__cache_get(const struct rb_root *root, sector_t block)
|
|
{
|
|
struct rb_node *n = root->rb_node;
|
|
struct dm_buffer *b;
|
|
|
|
while (n) {
|
|
b = container_of(n, struct dm_buffer, node);
|
|
|
|
if (b->block == block)
|
|
return b;
|
|
|
|
n = block < b->block ? n->rb_left : n->rb_right;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void __cache_inc_buffer(struct dm_buffer *b)
|
|
{
|
|
atomic_inc(&b->hold_count);
|
|
WRITE_ONCE(b->last_accessed, jiffies);
|
|
}
|
|
|
|
static struct dm_buffer *cache_get(struct dm_buffer_cache *bc, sector_t block)
|
|
{
|
|
struct dm_buffer *b;
|
|
|
|
cache_read_lock(bc, block);
|
|
b = __cache_get(&bc->trees[cache_index(block, bc->num_locks)].root, block);
|
|
if (b) {
|
|
lru_reference(&b->lru);
|
|
__cache_inc_buffer(b);
|
|
}
|
|
cache_read_unlock(bc, block);
|
|
|
|
return b;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Returns true if the hold count hits zero.
|
|
* threadsafe
|
|
*/
|
|
static bool cache_put(struct dm_buffer_cache *bc, struct dm_buffer *b)
|
|
{
|
|
bool r;
|
|
|
|
cache_read_lock(bc, b->block);
|
|
BUG_ON(!atomic_read(&b->hold_count));
|
|
r = atomic_dec_and_test(&b->hold_count);
|
|
cache_read_unlock(bc, b->block);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
typedef enum evict_result (*b_predicate)(struct dm_buffer *, void *);
|
|
|
|
/*
|
|
* Evicts a buffer based on a predicate. The oldest buffer that
|
|
* matches the predicate will be selected. In addition to the
|
|
* predicate the hold_count of the selected buffer will be zero.
|
|
*/
|
|
struct evict_wrapper {
|
|
struct lock_history *lh;
|
|
b_predicate pred;
|
|
void *context;
|
|
};
|
|
|
|
/*
|
|
* Wraps the buffer predicate turning it into an lru predicate. Adds
|
|
* extra test for hold_count.
|
|
*/
|
|
static enum evict_result __evict_pred(struct lru_entry *le, void *context)
|
|
{
|
|
struct evict_wrapper *w = context;
|
|
struct dm_buffer *b = le_to_buffer(le);
|
|
|
|
lh_next(w->lh, b->block);
|
|
|
|
if (atomic_read(&b->hold_count))
|
|
return ER_DONT_EVICT;
|
|
|
|
return w->pred(b, w->context);
|
|
}
|
|
|
|
static struct dm_buffer *__cache_evict(struct dm_buffer_cache *bc, int list_mode,
|
|
b_predicate pred, void *context,
|
|
struct lock_history *lh)
|
|
{
|
|
struct evict_wrapper w = {.lh = lh, .pred = pred, .context = context};
|
|
struct lru_entry *le;
|
|
struct dm_buffer *b;
|
|
|
|
le = lru_evict(&bc->lru[list_mode], __evict_pred, &w);
|
|
if (!le)
|
|
return NULL;
|
|
|
|
b = le_to_buffer(le);
|
|
/* __evict_pred will have locked the appropriate tree. */
|
|
rb_erase(&b->node, &bc->trees[cache_index(b->block, bc->num_locks)].root);
|
|
|
|
return b;
|
|
}
|
|
|
|
static struct dm_buffer *cache_evict(struct dm_buffer_cache *bc, int list_mode,
|
|
b_predicate pred, void *context)
|
|
{
|
|
struct dm_buffer *b;
|
|
struct lock_history lh;
|
|
|
|
lh_init(&lh, bc, true);
|
|
b = __cache_evict(bc, list_mode, pred, context, &lh);
|
|
lh_exit(&lh);
|
|
|
|
return b;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Mark a buffer as clean or dirty. Not threadsafe.
|
|
*/
|
|
static void cache_mark(struct dm_buffer_cache *bc, struct dm_buffer *b, int list_mode)
|
|
{
|
|
cache_write_lock(bc, b->block);
|
|
if (list_mode != b->list_mode) {
|
|
lru_remove(&bc->lru[b->list_mode], &b->lru);
|
|
b->list_mode = list_mode;
|
|
lru_insert(&bc->lru[b->list_mode], &b->lru);
|
|
}
|
|
cache_write_unlock(bc, b->block);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Runs through the lru associated with 'old_mode', if the predicate matches then
|
|
* it moves them to 'new_mode'. Not threadsafe.
|
|
*/
|
|
static void __cache_mark_many(struct dm_buffer_cache *bc, int old_mode, int new_mode,
|
|
b_predicate pred, void *context, struct lock_history *lh)
|
|
{
|
|
struct lru_entry *le;
|
|
struct dm_buffer *b;
|
|
struct evict_wrapper w = {.lh = lh, .pred = pred, .context = context};
|
|
|
|
while (true) {
|
|
le = lru_evict(&bc->lru[old_mode], __evict_pred, &w);
|
|
if (!le)
|
|
break;
|
|
|
|
b = le_to_buffer(le);
|
|
b->list_mode = new_mode;
|
|
lru_insert(&bc->lru[b->list_mode], &b->lru);
|
|
}
|
|
}
|
|
|
|
static void cache_mark_many(struct dm_buffer_cache *bc, int old_mode, int new_mode,
|
|
b_predicate pred, void *context)
|
|
{
|
|
struct lock_history lh;
|
|
|
|
lh_init(&lh, bc, true);
|
|
__cache_mark_many(bc, old_mode, new_mode, pred, context, &lh);
|
|
lh_exit(&lh);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Iterates through all clean or dirty entries calling a function for each
|
|
* entry. The callback may terminate the iteration early. Not threadsafe.
|
|
*/
|
|
|
|
/*
|
|
* Iterator functions should return one of these actions to indicate
|
|
* how the iteration should proceed.
|
|
*/
|
|
enum it_action {
|
|
IT_NEXT,
|
|
IT_COMPLETE,
|
|
};
|
|
|
|
typedef enum it_action (*iter_fn)(struct dm_buffer *b, void *context);
|
|
|
|
static void __cache_iterate(struct dm_buffer_cache *bc, int list_mode,
|
|
iter_fn fn, void *context, struct lock_history *lh)
|
|
{
|
|
struct lru *lru = &bc->lru[list_mode];
|
|
struct lru_entry *le, *first;
|
|
|
|
if (!lru->cursor)
|
|
return;
|
|
|
|
first = le = to_le(lru->cursor);
|
|
do {
|
|
struct dm_buffer *b = le_to_buffer(le);
|
|
|
|
lh_next(lh, b->block);
|
|
|
|
switch (fn(b, context)) {
|
|
case IT_NEXT:
|
|
break;
|
|
|
|
case IT_COMPLETE:
|
|
return;
|
|
}
|
|
cond_resched();
|
|
|
|
le = to_le(le->list.next);
|
|
} while (le != first);
|
|
}
|
|
|
|
static void cache_iterate(struct dm_buffer_cache *bc, int list_mode,
|
|
iter_fn fn, void *context)
|
|
{
|
|
struct lock_history lh;
|
|
|
|
lh_init(&lh, bc, false);
|
|
__cache_iterate(bc, list_mode, fn, context, &lh);
|
|
lh_exit(&lh);
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Passes ownership of the buffer to the cache. Returns false if the
|
|
* buffer was already present (in which case ownership does not pass).
|
|
* eg, a race with another thread.
|
|
*
|
|
* Holder count should be 1 on insertion.
|
|
*
|
|
* Not threadsafe.
|
|
*/
|
|
static bool __cache_insert(struct rb_root *root, struct dm_buffer *b)
|
|
{
|
|
struct rb_node **new = &root->rb_node, *parent = NULL;
|
|
struct dm_buffer *found;
|
|
|
|
while (*new) {
|
|
found = container_of(*new, struct dm_buffer, node);
|
|
|
|
if (found->block == b->block)
|
|
return false;
|
|
|
|
parent = *new;
|
|
new = b->block < found->block ?
|
|
&found->node.rb_left : &found->node.rb_right;
|
|
}
|
|
|
|
rb_link_node(&b->node, parent, new);
|
|
rb_insert_color(&b->node, root);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool cache_insert(struct dm_buffer_cache *bc, struct dm_buffer *b)
|
|
{
|
|
bool r;
|
|
|
|
if (WARN_ON_ONCE(b->list_mode >= LIST_SIZE))
|
|
return false;
|
|
|
|
cache_write_lock(bc, b->block);
|
|
BUG_ON(atomic_read(&b->hold_count) != 1);
|
|
r = __cache_insert(&bc->trees[cache_index(b->block, bc->num_locks)].root, b);
|
|
if (r)
|
|
lru_insert(&bc->lru[b->list_mode], &b->lru);
|
|
cache_write_unlock(bc, b->block);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
/*
|
|
* Removes buffer from cache, ownership of the buffer passes back to the caller.
|
|
* Fails if the hold_count is not one (ie. the caller holds the only reference).
|
|
*
|
|
* Not threadsafe.
|
|
*/
|
|
static bool cache_remove(struct dm_buffer_cache *bc, struct dm_buffer *b)
|
|
{
|
|
bool r;
|
|
|
|
cache_write_lock(bc, b->block);
|
|
|
|
if (atomic_read(&b->hold_count) != 1) {
|
|
r = false;
|
|
} else {
|
|
r = true;
|
|
rb_erase(&b->node, &bc->trees[cache_index(b->block, bc->num_locks)].root);
|
|
lru_remove(&bc->lru[b->list_mode], &b->lru);
|
|
}
|
|
|
|
cache_write_unlock(bc, b->block);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*--------------*/
|
|
|
|
typedef void (*b_release)(struct dm_buffer *);
|
|
|
|
static struct dm_buffer *__find_next(struct rb_root *root, sector_t block)
|
|
{
|
|
struct rb_node *n = root->rb_node;
|
|
struct dm_buffer *b;
|
|
struct dm_buffer *best = NULL;
|
|
|
|
while (n) {
|
|
b = container_of(n, struct dm_buffer, node);
|
|
|
|
if (b->block == block)
|
|
return b;
|
|
|
|
if (block <= b->block) {
|
|
n = n->rb_left;
|
|
best = b;
|
|
} else {
|
|
n = n->rb_right;
|
|
}
|
|
}
|
|
|
|
return best;
|
|
}
|
|
|
|
static void __remove_range(struct dm_buffer_cache *bc,
|
|
struct rb_root *root,
|
|
sector_t begin, sector_t end,
|
|
b_predicate pred, b_release release)
|
|
{
|
|
struct dm_buffer *b;
|
|
|
|
while (true) {
|
|
cond_resched();
|
|
|
|
b = __find_next(root, begin);
|
|
if (!b || (b->block >= end))
|
|
break;
|
|
|
|
begin = b->block + 1;
|
|
|
|
if (atomic_read(&b->hold_count))
|
|
continue;
|
|
|
|
if (pred(b, NULL) == ER_EVICT) {
|
|
rb_erase(&b->node, root);
|
|
lru_remove(&bc->lru[b->list_mode], &b->lru);
|
|
release(b);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void cache_remove_range(struct dm_buffer_cache *bc,
|
|
sector_t begin, sector_t end,
|
|
b_predicate pred, b_release release)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < bc->num_locks; i++) {
|
|
down_write(&bc->trees[i].lock);
|
|
__remove_range(bc, &bc->trees[i].root, begin, end, pred, release);
|
|
up_write(&bc->trees[i].lock);
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Linking of buffers:
|
|
* All buffers are linked to buffer_cache with their node field.
|
|
*
|
|
* Clean buffers that are not being written (B_WRITING not set)
|
|
* are linked to lru[LIST_CLEAN] with their lru_list field.
|
|
*
|
|
* Dirty and clean buffers that are being written are linked to
|
|
* lru[LIST_DIRTY] with their lru_list field. When the write
|
|
* finishes, the buffer cannot be relinked immediately (because we
|
|
* are in an interrupt context and relinking requires process
|
|
* context), so some clean-not-writing buffers can be held on
|
|
* dirty_lru too. They are later added to lru in the process
|
|
* context.
|
|
*/
|
|
struct dm_bufio_client {
|
|
struct block_device *bdev;
|
|
unsigned int block_size;
|
|
s8 sectors_per_block_bits;
|
|
|
|
bool no_sleep;
|
|
struct mutex lock;
|
|
spinlock_t spinlock;
|
|
|
|
int async_write_error;
|
|
|
|
void (*alloc_callback)(struct dm_buffer *buf);
|
|
void (*write_callback)(struct dm_buffer *buf);
|
|
struct kmem_cache *slab_buffer;
|
|
struct kmem_cache *slab_cache;
|
|
struct dm_io_client *dm_io;
|
|
|
|
struct list_head reserved_buffers;
|
|
unsigned int need_reserved_buffers;
|
|
|
|
unsigned int minimum_buffers;
|
|
|
|
sector_t start;
|
|
|
|
struct shrinker shrinker;
|
|
struct work_struct shrink_work;
|
|
atomic_long_t need_shrink;
|
|
|
|
wait_queue_head_t free_buffer_wait;
|
|
|
|
struct list_head client_list;
|
|
|
|
/*
|
|
* Used by global_cleanup to sort the clients list.
|
|
*/
|
|
unsigned long oldest_buffer;
|
|
|
|
struct dm_buffer_cache cache; /* must be last member */
|
|
};
|
|
|
|
static DEFINE_STATIC_KEY_FALSE(no_sleep_enabled);
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
#define dm_bufio_in_request() (!!current->bio_list)
|
|
|
|
static void dm_bufio_lock(struct dm_bufio_client *c)
|
|
{
|
|
if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
|
|
spin_lock_bh(&c->spinlock);
|
|
else
|
|
mutex_lock_nested(&c->lock, dm_bufio_in_request());
|
|
}
|
|
|
|
static void dm_bufio_unlock(struct dm_bufio_client *c)
|
|
{
|
|
if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
|
|
spin_unlock_bh(&c->spinlock);
|
|
else
|
|
mutex_unlock(&c->lock);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Default cache size: available memory divided by the ratio.
|
|
*/
|
|
static unsigned long dm_bufio_default_cache_size;
|
|
|
|
/*
|
|
* Total cache size set by the user.
|
|
*/
|
|
static unsigned long dm_bufio_cache_size;
|
|
|
|
/*
|
|
* A copy of dm_bufio_cache_size because dm_bufio_cache_size can change
|
|
* at any time. If it disagrees, the user has changed cache size.
|
|
*/
|
|
static unsigned long dm_bufio_cache_size_latch;
|
|
|
|
static DEFINE_SPINLOCK(global_spinlock);
|
|
|
|
/*
|
|
* Buffers are freed after this timeout
|
|
*/
|
|
static unsigned int dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;
|
|
static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
|
|
|
|
static unsigned long dm_bufio_peak_allocated;
|
|
static unsigned long dm_bufio_allocated_kmem_cache;
|
|
static unsigned long dm_bufio_allocated_get_free_pages;
|
|
static unsigned long dm_bufio_allocated_vmalloc;
|
|
static unsigned long dm_bufio_current_allocated;
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* The current number of clients.
|
|
*/
|
|
static int dm_bufio_client_count;
|
|
|
|
/*
|
|
* The list of all clients.
|
|
*/
|
|
static LIST_HEAD(dm_bufio_all_clients);
|
|
|
|
/*
|
|
* This mutex protects dm_bufio_cache_size_latch and dm_bufio_client_count
|
|
*/
|
|
static DEFINE_MUTEX(dm_bufio_clients_lock);
|
|
|
|
static struct workqueue_struct *dm_bufio_wq;
|
|
static struct delayed_work dm_bufio_cleanup_old_work;
|
|
static struct work_struct dm_bufio_replacement_work;
|
|
|
|
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
static void buffer_record_stack(struct dm_buffer *b)
|
|
{
|
|
b->stack_len = stack_trace_save(b->stack_entries, MAX_STACK, 2);
|
|
}
|
|
#endif
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void adjust_total_allocated(struct dm_buffer *b, bool unlink)
|
|
{
|
|
unsigned char data_mode;
|
|
long diff;
|
|
|
|
static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
|
|
&dm_bufio_allocated_kmem_cache,
|
|
&dm_bufio_allocated_get_free_pages,
|
|
&dm_bufio_allocated_vmalloc,
|
|
};
|
|
|
|
data_mode = b->data_mode;
|
|
diff = (long)b->c->block_size;
|
|
if (unlink)
|
|
diff = -diff;
|
|
|
|
spin_lock(&global_spinlock);
|
|
|
|
*class_ptr[data_mode] += diff;
|
|
|
|
dm_bufio_current_allocated += diff;
|
|
|
|
if (dm_bufio_current_allocated > dm_bufio_peak_allocated)
|
|
dm_bufio_peak_allocated = dm_bufio_current_allocated;
|
|
|
|
if (!unlink) {
|
|
if (dm_bufio_current_allocated > dm_bufio_cache_size)
|
|
queue_work(dm_bufio_wq, &dm_bufio_replacement_work);
|
|
}
|
|
|
|
spin_unlock(&global_spinlock);
|
|
}
|
|
|
|
/*
|
|
* Change the number of clients and recalculate per-client limit.
|
|
*/
|
|
static void __cache_size_refresh(void)
|
|
{
|
|
if (WARN_ON(!mutex_is_locked(&dm_bufio_clients_lock)))
|
|
return;
|
|
if (WARN_ON(dm_bufio_client_count < 0))
|
|
return;
|
|
|
|
dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size);
|
|
|
|
/*
|
|
* Use default if set to 0 and report the actual cache size used.
|
|
*/
|
|
if (!dm_bufio_cache_size_latch) {
|
|
(void)cmpxchg(&dm_bufio_cache_size, 0,
|
|
dm_bufio_default_cache_size);
|
|
dm_bufio_cache_size_latch = dm_bufio_default_cache_size;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocating buffer data.
|
|
*
|
|
* Small buffers are allocated with kmem_cache, to use space optimally.
|
|
*
|
|
* For large buffers, we choose between get_free_pages and vmalloc.
|
|
* Each has advantages and disadvantages.
|
|
*
|
|
* __get_free_pages can randomly fail if the memory is fragmented.
|
|
* __vmalloc won't randomly fail, but vmalloc space is limited (it may be
|
|
* as low as 128M) so using it for caching is not appropriate.
|
|
*
|
|
* If the allocation may fail we use __get_free_pages. Memory fragmentation
|
|
* won't have a fatal effect here, but it just causes flushes of some other
|
|
* buffers and more I/O will be performed. Don't use __get_free_pages if it
|
|
* always fails (i.e. order > MAX_ORDER).
|
|
*
|
|
* If the allocation shouldn't fail we use __vmalloc. This is only for the
|
|
* initial reserve allocation, so there's no risk of wasting all vmalloc
|
|
* space.
|
|
*/
|
|
static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
|
|
unsigned char *data_mode)
|
|
{
|
|
if (unlikely(c->slab_cache != NULL)) {
|
|
*data_mode = DATA_MODE_SLAB;
|
|
return kmem_cache_alloc(c->slab_cache, gfp_mask);
|
|
}
|
|
|
|
if (c->block_size <= KMALLOC_MAX_SIZE &&
|
|
gfp_mask & __GFP_NORETRY) {
|
|
*data_mode = DATA_MODE_GET_FREE_PAGES;
|
|
return (void *)__get_free_pages(gfp_mask,
|
|
c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
|
|
}
|
|
|
|
*data_mode = DATA_MODE_VMALLOC;
|
|
|
|
return __vmalloc(c->block_size, gfp_mask);
|
|
}
|
|
|
|
/*
|
|
* Free buffer's data.
|
|
*/
|
|
static void free_buffer_data(struct dm_bufio_client *c,
|
|
void *data, unsigned char data_mode)
|
|
{
|
|
switch (data_mode) {
|
|
case DATA_MODE_SLAB:
|
|
kmem_cache_free(c->slab_cache, data);
|
|
break;
|
|
|
|
case DATA_MODE_GET_FREE_PAGES:
|
|
free_pages((unsigned long)data,
|
|
c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
|
|
break;
|
|
|
|
case DATA_MODE_VMALLOC:
|
|
vfree(data);
|
|
break;
|
|
|
|
default:
|
|
DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d",
|
|
data_mode);
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate buffer and its data.
|
|
*/
|
|
static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask)
|
|
{
|
|
struct dm_buffer *b = kmem_cache_alloc(c->slab_buffer, gfp_mask);
|
|
|
|
if (!b)
|
|
return NULL;
|
|
|
|
b->c = c;
|
|
|
|
b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode);
|
|
if (!b->data) {
|
|
kmem_cache_free(c->slab_buffer, b);
|
|
return NULL;
|
|
}
|
|
adjust_total_allocated(b, false);
|
|
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
b->stack_len = 0;
|
|
#endif
|
|
return b;
|
|
}
|
|
|
|
/*
|
|
* Free buffer and its data.
|
|
*/
|
|
static void free_buffer(struct dm_buffer *b)
|
|
{
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
adjust_total_allocated(b, true);
|
|
free_buffer_data(c, b->data, b->data_mode);
|
|
kmem_cache_free(c->slab_buffer, b);
|
|
}
|
|
|
|
/*
|
|
*--------------------------------------------------------------------------
|
|
* Submit I/O on the buffer.
|
|
*
|
|
* Bio interface is faster but it has some problems:
|
|
* the vector list is limited (increasing this limit increases
|
|
* memory-consumption per buffer, so it is not viable);
|
|
*
|
|
* the memory must be direct-mapped, not vmalloced;
|
|
*
|
|
* If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and
|
|
* it is not vmalloced, try using the bio interface.
|
|
*
|
|
* If the buffer is big, if it is vmalloced or if the underlying device
|
|
* rejects the bio because it is too large, use dm-io layer to do the I/O.
|
|
* The dm-io layer splits the I/O into multiple requests, avoiding the above
|
|
* shortcomings.
|
|
*--------------------------------------------------------------------------
|
|
*/
|
|
|
|
/*
|
|
* dm-io completion routine. It just calls b->bio.bi_end_io, pretending
|
|
* that the request was handled directly with bio interface.
|
|
*/
|
|
static void dmio_complete(unsigned long error, void *context)
|
|
{
|
|
struct dm_buffer *b = context;
|
|
|
|
b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0);
|
|
}
|
|
|
|
static void use_dmio(struct dm_buffer *b, enum req_op op, sector_t sector,
|
|
unsigned int n_sectors, unsigned int offset)
|
|
{
|
|
int r;
|
|
struct dm_io_request io_req = {
|
|
.bi_opf = op,
|
|
.notify.fn = dmio_complete,
|
|
.notify.context = b,
|
|
.client = b->c->dm_io,
|
|
};
|
|
struct dm_io_region region = {
|
|
.bdev = b->c->bdev,
|
|
.sector = sector,
|
|
.count = n_sectors,
|
|
};
|
|
|
|
if (b->data_mode != DATA_MODE_VMALLOC) {
|
|
io_req.mem.type = DM_IO_KMEM;
|
|
io_req.mem.ptr.addr = (char *)b->data + offset;
|
|
} else {
|
|
io_req.mem.type = DM_IO_VMA;
|
|
io_req.mem.ptr.vma = (char *)b->data + offset;
|
|
}
|
|
|
|
r = dm_io(&io_req, 1, ®ion, NULL);
|
|
if (unlikely(r))
|
|
b->end_io(b, errno_to_blk_status(r));
|
|
}
|
|
|
|
static void bio_complete(struct bio *bio)
|
|
{
|
|
struct dm_buffer *b = bio->bi_private;
|
|
blk_status_t status = bio->bi_status;
|
|
|
|
bio_uninit(bio);
|
|
kfree(bio);
|
|
b->end_io(b, status);
|
|
}
|
|
|
|
static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
|
|
unsigned int n_sectors, unsigned int offset)
|
|
{
|
|
struct bio *bio;
|
|
char *ptr;
|
|
unsigned int len;
|
|
|
|
bio = bio_kmalloc(1, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
|
|
if (!bio) {
|
|
use_dmio(b, op, sector, n_sectors, offset);
|
|
return;
|
|
}
|
|
bio_init(bio, b->c->bdev, bio->bi_inline_vecs, 1, op);
|
|
bio->bi_iter.bi_sector = sector;
|
|
bio->bi_end_io = bio_complete;
|
|
bio->bi_private = b;
|
|
|
|
ptr = (char *)b->data + offset;
|
|
len = n_sectors << SECTOR_SHIFT;
|
|
|
|
__bio_add_page(bio, virt_to_page(ptr), len, offset_in_page(ptr));
|
|
|
|
submit_bio(bio);
|
|
}
|
|
|
|
static inline sector_t block_to_sector(struct dm_bufio_client *c, sector_t block)
|
|
{
|
|
sector_t sector;
|
|
|
|
if (likely(c->sectors_per_block_bits >= 0))
|
|
sector = block << c->sectors_per_block_bits;
|
|
else
|
|
sector = block * (c->block_size >> SECTOR_SHIFT);
|
|
sector += c->start;
|
|
|
|
return sector;
|
|
}
|
|
|
|
static void submit_io(struct dm_buffer *b, enum req_op op,
|
|
void (*end_io)(struct dm_buffer *, blk_status_t))
|
|
{
|
|
unsigned int n_sectors;
|
|
sector_t sector;
|
|
unsigned int offset, end;
|
|
|
|
b->end_io = end_io;
|
|
|
|
sector = block_to_sector(b->c, b->block);
|
|
|
|
if (op != REQ_OP_WRITE) {
|
|
n_sectors = b->c->block_size >> SECTOR_SHIFT;
|
|
offset = 0;
|
|
} else {
|
|
if (b->c->write_callback)
|
|
b->c->write_callback(b);
|
|
offset = b->write_start;
|
|
end = b->write_end;
|
|
offset &= -DM_BUFIO_WRITE_ALIGN;
|
|
end += DM_BUFIO_WRITE_ALIGN - 1;
|
|
end &= -DM_BUFIO_WRITE_ALIGN;
|
|
if (unlikely(end > b->c->block_size))
|
|
end = b->c->block_size;
|
|
|
|
sector += offset >> SECTOR_SHIFT;
|
|
n_sectors = (end - offset) >> SECTOR_SHIFT;
|
|
}
|
|
|
|
if (b->data_mode != DATA_MODE_VMALLOC)
|
|
use_bio(b, op, sector, n_sectors, offset);
|
|
else
|
|
use_dmio(b, op, sector, n_sectors, offset);
|
|
}
|
|
|
|
/*
|
|
*--------------------------------------------------------------
|
|
* Writing dirty buffers
|
|
*--------------------------------------------------------------
|
|
*/
|
|
|
|
/*
|
|
* The endio routine for write.
|
|
*
|
|
* Set the error, clear B_WRITING bit and wake anyone who was waiting on
|
|
* it.
|
|
*/
|
|
static void write_endio(struct dm_buffer *b, blk_status_t status)
|
|
{
|
|
b->write_error = status;
|
|
if (unlikely(status)) {
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
(void)cmpxchg(&c->async_write_error, 0,
|
|
blk_status_to_errno(status));
|
|
}
|
|
|
|
BUG_ON(!test_bit(B_WRITING, &b->state));
|
|
|
|
smp_mb__before_atomic();
|
|
clear_bit(B_WRITING, &b->state);
|
|
smp_mb__after_atomic();
|
|
|
|
wake_up_bit(&b->state, B_WRITING);
|
|
}
|
|
|
|
/*
|
|
* Initiate a write on a dirty buffer, but don't wait for it.
|
|
*
|
|
* - If the buffer is not dirty, exit.
|
|
* - If there some previous write going on, wait for it to finish (we can't
|
|
* have two writes on the same buffer simultaneously).
|
|
* - Submit our write and don't wait on it. We set B_WRITING indicating
|
|
* that there is a write in progress.
|
|
*/
|
|
static void __write_dirty_buffer(struct dm_buffer *b,
|
|
struct list_head *write_list)
|
|
{
|
|
if (!test_bit(B_DIRTY, &b->state))
|
|
return;
|
|
|
|
clear_bit(B_DIRTY, &b->state);
|
|
wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
|
|
|
|
b->write_start = b->dirty_start;
|
|
b->write_end = b->dirty_end;
|
|
|
|
if (!write_list)
|
|
submit_io(b, REQ_OP_WRITE, write_endio);
|
|
else
|
|
list_add_tail(&b->write_list, write_list);
|
|
}
|
|
|
|
static void __flush_write_list(struct list_head *write_list)
|
|
{
|
|
struct blk_plug plug;
|
|
|
|
blk_start_plug(&plug);
|
|
while (!list_empty(write_list)) {
|
|
struct dm_buffer *b =
|
|
list_entry(write_list->next, struct dm_buffer, write_list);
|
|
list_del(&b->write_list);
|
|
submit_io(b, REQ_OP_WRITE, write_endio);
|
|
cond_resched();
|
|
}
|
|
blk_finish_plug(&plug);
|
|
}
|
|
|
|
/*
|
|
* Wait until any activity on the buffer finishes. Possibly write the
|
|
* buffer if it is dirty. When this function finishes, there is no I/O
|
|
* running on the buffer and the buffer is not dirty.
|
|
*/
|
|
static void __make_buffer_clean(struct dm_buffer *b)
|
|
{
|
|
BUG_ON(atomic_read(&b->hold_count));
|
|
|
|
/* smp_load_acquire() pairs with read_endio()'s smp_mb__before_atomic() */
|
|
if (!smp_load_acquire(&b->state)) /* fast case */
|
|
return;
|
|
|
|
wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
|
|
__write_dirty_buffer(b, NULL);
|
|
wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
|
|
}
|
|
|
|
static enum evict_result is_clean(struct dm_buffer *b, void *context)
|
|
{
|
|
struct dm_bufio_client *c = context;
|
|
|
|
/* These should never happen */
|
|
if (WARN_ON_ONCE(test_bit(B_WRITING, &b->state)))
|
|
return ER_DONT_EVICT;
|
|
if (WARN_ON_ONCE(test_bit(B_DIRTY, &b->state)))
|
|
return ER_DONT_EVICT;
|
|
if (WARN_ON_ONCE(b->list_mode != LIST_CLEAN))
|
|
return ER_DONT_EVICT;
|
|
|
|
if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep &&
|
|
unlikely(test_bit(B_READING, &b->state)))
|
|
return ER_DONT_EVICT;
|
|
|
|
return ER_EVICT;
|
|
}
|
|
|
|
static enum evict_result is_dirty(struct dm_buffer *b, void *context)
|
|
{
|
|
/* These should never happen */
|
|
if (WARN_ON_ONCE(test_bit(B_READING, &b->state)))
|
|
return ER_DONT_EVICT;
|
|
if (WARN_ON_ONCE(b->list_mode != LIST_DIRTY))
|
|
return ER_DONT_EVICT;
|
|
|
|
return ER_EVICT;
|
|
}
|
|
|
|
/*
|
|
* Find some buffer that is not held by anybody, clean it, unlink it and
|
|
* return it.
|
|
*/
|
|
static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
|
|
{
|
|
struct dm_buffer *b;
|
|
|
|
b = cache_evict(&c->cache, LIST_CLEAN, is_clean, c);
|
|
if (b) {
|
|
/* this also waits for pending reads */
|
|
__make_buffer_clean(b);
|
|
return b;
|
|
}
|
|
|
|
if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep)
|
|
return NULL;
|
|
|
|
b = cache_evict(&c->cache, LIST_DIRTY, is_dirty, NULL);
|
|
if (b) {
|
|
__make_buffer_clean(b);
|
|
return b;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Wait until some other threads free some buffer or release hold count on
|
|
* some buffer.
|
|
*
|
|
* This function is entered with c->lock held, drops it and regains it
|
|
* before exiting.
|
|
*/
|
|
static void __wait_for_free_buffer(struct dm_bufio_client *c)
|
|
{
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
add_wait_queue(&c->free_buffer_wait, &wait);
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
dm_bufio_unlock(c);
|
|
|
|
/*
|
|
* It's possible to miss a wake up event since we don't always
|
|
* hold c->lock when wake_up is called. So we have a timeout here,
|
|
* just in case.
|
|
*/
|
|
io_schedule_timeout(5 * HZ);
|
|
|
|
remove_wait_queue(&c->free_buffer_wait, &wait);
|
|
|
|
dm_bufio_lock(c);
|
|
}
|
|
|
|
enum new_flag {
|
|
NF_FRESH = 0,
|
|
NF_READ = 1,
|
|
NF_GET = 2,
|
|
NF_PREFETCH = 3
|
|
};
|
|
|
|
/*
|
|
* Allocate a new buffer. If the allocation is not possible, wait until
|
|
* some other thread frees a buffer.
|
|
*
|
|
* May drop the lock and regain it.
|
|
*/
|
|
static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
|
|
{
|
|
struct dm_buffer *b;
|
|
bool tried_noio_alloc = false;
|
|
|
|
/*
|
|
* dm-bufio is resistant to allocation failures (it just keeps
|
|
* one buffer reserved in cases all the allocations fail).
|
|
* So set flags to not try too hard:
|
|
* GFP_NOWAIT: don't wait; if we need to sleep we'll release our
|
|
* mutex and wait ourselves.
|
|
* __GFP_NORETRY: don't retry and rather return failure
|
|
* __GFP_NOMEMALLOC: don't use emergency reserves
|
|
* __GFP_NOWARN: don't print a warning in case of failure
|
|
*
|
|
* For debugging, if we set the cache size to 1, no new buffers will
|
|
* be allocated.
|
|
*/
|
|
while (1) {
|
|
if (dm_bufio_cache_size_latch != 1) {
|
|
b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
|
if (b)
|
|
return b;
|
|
}
|
|
|
|
if (nf == NF_PREFETCH)
|
|
return NULL;
|
|
|
|
if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) {
|
|
dm_bufio_unlock(c);
|
|
b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
|
|
dm_bufio_lock(c);
|
|
if (b)
|
|
return b;
|
|
tried_noio_alloc = true;
|
|
}
|
|
|
|
if (!list_empty(&c->reserved_buffers)) {
|
|
b = list_to_buffer(c->reserved_buffers.next);
|
|
list_del(&b->lru.list);
|
|
c->need_reserved_buffers++;
|
|
|
|
return b;
|
|
}
|
|
|
|
b = __get_unclaimed_buffer(c);
|
|
if (b)
|
|
return b;
|
|
|
|
__wait_for_free_buffer(c);
|
|
}
|
|
}
|
|
|
|
static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf)
|
|
{
|
|
struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf);
|
|
|
|
if (!b)
|
|
return NULL;
|
|
|
|
if (c->alloc_callback)
|
|
c->alloc_callback(b);
|
|
|
|
return b;
|
|
}
|
|
|
|
/*
|
|
* Free a buffer and wake other threads waiting for free buffers.
|
|
*/
|
|
static void __free_buffer_wake(struct dm_buffer *b)
|
|
{
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
b->block = -1;
|
|
if (!c->need_reserved_buffers)
|
|
free_buffer(b);
|
|
else {
|
|
list_add(&b->lru.list, &c->reserved_buffers);
|
|
c->need_reserved_buffers--;
|
|
}
|
|
|
|
/*
|
|
* We hold the bufio lock here, so no one can add entries to the
|
|
* wait queue anyway.
|
|
*/
|
|
if (unlikely(waitqueue_active(&c->free_buffer_wait)))
|
|
wake_up(&c->free_buffer_wait);
|
|
}
|
|
|
|
static enum evict_result cleaned(struct dm_buffer *b, void *context)
|
|
{
|
|
if (WARN_ON_ONCE(test_bit(B_READING, &b->state)))
|
|
return ER_DONT_EVICT; /* should never happen */
|
|
|
|
if (test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state))
|
|
return ER_DONT_EVICT;
|
|
else
|
|
return ER_EVICT;
|
|
}
|
|
|
|
static void __move_clean_buffers(struct dm_bufio_client *c)
|
|
{
|
|
cache_mark_many(&c->cache, LIST_DIRTY, LIST_CLEAN, cleaned, NULL);
|
|
}
|
|
|
|
struct write_context {
|
|
int no_wait;
|
|
struct list_head *write_list;
|
|
};
|
|
|
|
static enum it_action write_one(struct dm_buffer *b, void *context)
|
|
{
|
|
struct write_context *wc = context;
|
|
|
|
if (wc->no_wait && test_bit(B_WRITING, &b->state))
|
|
return IT_COMPLETE;
|
|
|
|
__write_dirty_buffer(b, wc->write_list);
|
|
return IT_NEXT;
|
|
}
|
|
|
|
static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait,
|
|
struct list_head *write_list)
|
|
{
|
|
struct write_context wc = {.no_wait = no_wait, .write_list = write_list};
|
|
|
|
__move_clean_buffers(c);
|
|
cache_iterate(&c->cache, LIST_DIRTY, write_one, &wc);
|
|
}
|
|
|
|
/*
|
|
* Check if we're over watermark.
|
|
* If we are over threshold_buffers, start freeing buffers.
|
|
* If we're over "limit_buffers", block until we get under the limit.
|
|
*/
|
|
static void __check_watermark(struct dm_bufio_client *c,
|
|
struct list_head *write_list)
|
|
{
|
|
if (cache_count(&c->cache, LIST_DIRTY) >
|
|
cache_count(&c->cache, LIST_CLEAN) * DM_BUFIO_WRITEBACK_RATIO)
|
|
__write_dirty_buffers_async(c, 1, write_list);
|
|
}
|
|
|
|
/*
|
|
*--------------------------------------------------------------
|
|
* Getting a buffer
|
|
*--------------------------------------------------------------
|
|
*/
|
|
|
|
static void cache_put_and_wake(struct dm_bufio_client *c, struct dm_buffer *b)
|
|
{
|
|
/*
|
|
* Relying on waitqueue_active() is racey, but we sleep
|
|
* with schedule_timeout anyway.
|
|
*/
|
|
if (cache_put(&c->cache, b) &&
|
|
unlikely(waitqueue_active(&c->free_buffer_wait)))
|
|
wake_up(&c->free_buffer_wait);
|
|
}
|
|
|
|
/*
|
|
* This assumes you have already checked the cache to see if the buffer
|
|
* is already present (it will recheck after dropping the lock for allocation).
|
|
*/
|
|
static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block,
|
|
enum new_flag nf, int *need_submit,
|
|
struct list_head *write_list)
|
|
{
|
|
struct dm_buffer *b, *new_b = NULL;
|
|
|
|
*need_submit = 0;
|
|
|
|
/* This can't be called with NF_GET */
|
|
if (WARN_ON_ONCE(nf == NF_GET))
|
|
return NULL;
|
|
|
|
new_b = __alloc_buffer_wait(c, nf);
|
|
if (!new_b)
|
|
return NULL;
|
|
|
|
/*
|
|
* We've had a period where the mutex was unlocked, so need to
|
|
* recheck the buffer tree.
|
|
*/
|
|
b = cache_get(&c->cache, block);
|
|
if (b) {
|
|
__free_buffer_wake(new_b);
|
|
goto found_buffer;
|
|
}
|
|
|
|
__check_watermark(c, write_list);
|
|
|
|
b = new_b;
|
|
atomic_set(&b->hold_count, 1);
|
|
WRITE_ONCE(b->last_accessed, jiffies);
|
|
b->block = block;
|
|
b->read_error = 0;
|
|
b->write_error = 0;
|
|
b->list_mode = LIST_CLEAN;
|
|
|
|
if (nf == NF_FRESH)
|
|
b->state = 0;
|
|
else {
|
|
b->state = 1 << B_READING;
|
|
*need_submit = 1;
|
|
}
|
|
|
|
/*
|
|
* We mustn't insert into the cache until the B_READING state
|
|
* is set. Otherwise another thread could get it and use
|
|
* it before it had been read.
|
|
*/
|
|
cache_insert(&c->cache, b);
|
|
|
|
return b;
|
|
|
|
found_buffer:
|
|
if (nf == NF_PREFETCH) {
|
|
cache_put_and_wake(c, b);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Note: it is essential that we don't wait for the buffer to be
|
|
* read if dm_bufio_get function is used. Both dm_bufio_get and
|
|
* dm_bufio_prefetch can be used in the driver request routine.
|
|
* If the user called both dm_bufio_prefetch and dm_bufio_get on
|
|
* the same buffer, it would deadlock if we waited.
|
|
*/
|
|
if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) {
|
|
cache_put_and_wake(c, b);
|
|
return NULL;
|
|
}
|
|
|
|
return b;
|
|
}
|
|
|
|
/*
|
|
* The endio routine for reading: set the error, clear the bit and wake up
|
|
* anyone waiting on the buffer.
|
|
*/
|
|
static void read_endio(struct dm_buffer *b, blk_status_t status)
|
|
{
|
|
b->read_error = status;
|
|
|
|
BUG_ON(!test_bit(B_READING, &b->state));
|
|
|
|
smp_mb__before_atomic();
|
|
clear_bit(B_READING, &b->state);
|
|
smp_mb__after_atomic();
|
|
|
|
wake_up_bit(&b->state, B_READING);
|
|
}
|
|
|
|
/*
|
|
* A common routine for dm_bufio_new and dm_bufio_read. Operation of these
|
|
* functions is similar except that dm_bufio_new doesn't read the
|
|
* buffer from the disk (assuming that the caller overwrites all the data
|
|
* and uses dm_bufio_mark_buffer_dirty to write new data back).
|
|
*/
|
|
static void *new_read(struct dm_bufio_client *c, sector_t block,
|
|
enum new_flag nf, struct dm_buffer **bp)
|
|
{
|
|
int need_submit = 0;
|
|
struct dm_buffer *b;
|
|
|
|
LIST_HEAD(write_list);
|
|
|
|
*bp = NULL;
|
|
|
|
/*
|
|
* Fast path, hopefully the block is already in the cache. No need
|
|
* to get the client lock for this.
|
|
*/
|
|
b = cache_get(&c->cache, block);
|
|
if (b) {
|
|
if (nf == NF_PREFETCH) {
|
|
cache_put_and_wake(c, b);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Note: it is essential that we don't wait for the buffer to be
|
|
* read if dm_bufio_get function is used. Both dm_bufio_get and
|
|
* dm_bufio_prefetch can be used in the driver request routine.
|
|
* If the user called both dm_bufio_prefetch and dm_bufio_get on
|
|
* the same buffer, it would deadlock if we waited.
|
|
*/
|
|
if (nf == NF_GET && unlikely(test_bit_acquire(B_READING, &b->state))) {
|
|
cache_put_and_wake(c, b);
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
if (!b) {
|
|
if (nf == NF_GET)
|
|
return NULL;
|
|
|
|
dm_bufio_lock(c);
|
|
b = __bufio_new(c, block, nf, &need_submit, &write_list);
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
if (b && (atomic_read(&b->hold_count) == 1))
|
|
buffer_record_stack(b);
|
|
#endif
|
|
|
|
__flush_write_list(&write_list);
|
|
|
|
if (!b)
|
|
return NULL;
|
|
|
|
if (need_submit)
|
|
submit_io(b, REQ_OP_READ, read_endio);
|
|
|
|
wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
|
|
|
|
if (b->read_error) {
|
|
int error = blk_status_to_errno(b->read_error);
|
|
|
|
dm_bufio_release(b);
|
|
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
*bp = b;
|
|
|
|
return b->data;
|
|
}
|
|
|
|
void *dm_bufio_get(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp)
|
|
{
|
|
return new_read(c, block, NF_GET, bp);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get);
|
|
|
|
void *dm_bufio_read(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp)
|
|
{
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
return new_read(c, block, NF_READ, bp);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_read);
|
|
|
|
void *dm_bufio_new(struct dm_bufio_client *c, sector_t block,
|
|
struct dm_buffer **bp)
|
|
{
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
return new_read(c, block, NF_FRESH, bp);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_new);
|
|
|
|
void dm_bufio_prefetch(struct dm_bufio_client *c,
|
|
sector_t block, unsigned int n_blocks)
|
|
{
|
|
struct blk_plug plug;
|
|
|
|
LIST_HEAD(write_list);
|
|
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return; /* should never happen */
|
|
|
|
blk_start_plug(&plug);
|
|
|
|
for (; n_blocks--; block++) {
|
|
int need_submit;
|
|
struct dm_buffer *b;
|
|
|
|
b = cache_get(&c->cache, block);
|
|
if (b) {
|
|
/* already in cache */
|
|
cache_put_and_wake(c, b);
|
|
continue;
|
|
}
|
|
|
|
dm_bufio_lock(c);
|
|
b = __bufio_new(c, block, NF_PREFETCH, &need_submit,
|
|
&write_list);
|
|
if (unlikely(!list_empty(&write_list))) {
|
|
dm_bufio_unlock(c);
|
|
blk_finish_plug(&plug);
|
|
__flush_write_list(&write_list);
|
|
blk_start_plug(&plug);
|
|
dm_bufio_lock(c);
|
|
}
|
|
if (unlikely(b != NULL)) {
|
|
dm_bufio_unlock(c);
|
|
|
|
if (need_submit)
|
|
submit_io(b, REQ_OP_READ, read_endio);
|
|
dm_bufio_release(b);
|
|
|
|
cond_resched();
|
|
|
|
if (!n_blocks)
|
|
goto flush_plug;
|
|
dm_bufio_lock(c);
|
|
}
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
flush_plug:
|
|
blk_finish_plug(&plug);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
|
|
|
|
void dm_bufio_release(struct dm_buffer *b)
|
|
{
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
/*
|
|
* If there were errors on the buffer, and the buffer is not
|
|
* to be written, free the buffer. There is no point in caching
|
|
* invalid buffer.
|
|
*/
|
|
if ((b->read_error || b->write_error) &&
|
|
!test_bit_acquire(B_READING, &b->state) &&
|
|
!test_bit(B_WRITING, &b->state) &&
|
|
!test_bit(B_DIRTY, &b->state)) {
|
|
dm_bufio_lock(c);
|
|
|
|
/* cache remove can fail if there are other holders */
|
|
if (cache_remove(&c->cache, b)) {
|
|
__free_buffer_wake(b);
|
|
dm_bufio_unlock(c);
|
|
return;
|
|
}
|
|
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
cache_put_and_wake(c, b);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_release);
|
|
|
|
void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b,
|
|
unsigned int start, unsigned int end)
|
|
{
|
|
struct dm_bufio_client *c = b->c;
|
|
|
|
BUG_ON(start >= end);
|
|
BUG_ON(end > b->c->block_size);
|
|
|
|
dm_bufio_lock(c);
|
|
|
|
BUG_ON(test_bit(B_READING, &b->state));
|
|
|
|
if (!test_and_set_bit(B_DIRTY, &b->state)) {
|
|
b->dirty_start = start;
|
|
b->dirty_end = end;
|
|
cache_mark(&c->cache, b, LIST_DIRTY);
|
|
} else {
|
|
if (start < b->dirty_start)
|
|
b->dirty_start = start;
|
|
if (end > b->dirty_end)
|
|
b->dirty_end = end;
|
|
}
|
|
|
|
dm_bufio_unlock(c);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty);
|
|
|
|
void dm_bufio_mark_buffer_dirty(struct dm_buffer *b)
|
|
{
|
|
dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
|
|
|
|
void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c)
|
|
{
|
|
LIST_HEAD(write_list);
|
|
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return; /* should never happen */
|
|
|
|
dm_bufio_lock(c);
|
|
__write_dirty_buffers_async(c, 0, &write_list);
|
|
dm_bufio_unlock(c);
|
|
__flush_write_list(&write_list);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async);
|
|
|
|
/*
|
|
* For performance, it is essential that the buffers are written asynchronously
|
|
* and simultaneously (so that the block layer can merge the writes) and then
|
|
* waited upon.
|
|
*
|
|
* Finally, we flush hardware disk cache.
|
|
*/
|
|
static bool is_writing(struct lru_entry *e, void *context)
|
|
{
|
|
struct dm_buffer *b = le_to_buffer(e);
|
|
|
|
return test_bit(B_WRITING, &b->state);
|
|
}
|
|
|
|
int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c)
|
|
{
|
|
int a, f;
|
|
unsigned long nr_buffers;
|
|
struct lru_entry *e;
|
|
struct lru_iter it;
|
|
|
|
LIST_HEAD(write_list);
|
|
|
|
dm_bufio_lock(c);
|
|
__write_dirty_buffers_async(c, 0, &write_list);
|
|
dm_bufio_unlock(c);
|
|
__flush_write_list(&write_list);
|
|
dm_bufio_lock(c);
|
|
|
|
nr_buffers = cache_count(&c->cache, LIST_DIRTY);
|
|
lru_iter_begin(&c->cache.lru[LIST_DIRTY], &it);
|
|
while ((e = lru_iter_next(&it, is_writing, c))) {
|
|
struct dm_buffer *b = le_to_buffer(e);
|
|
__cache_inc_buffer(b);
|
|
|
|
BUG_ON(test_bit(B_READING, &b->state));
|
|
|
|
if (nr_buffers) {
|
|
nr_buffers--;
|
|
dm_bufio_unlock(c);
|
|
wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
|
|
dm_bufio_lock(c);
|
|
} else {
|
|
wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
|
|
}
|
|
|
|
if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state))
|
|
cache_mark(&c->cache, b, LIST_CLEAN);
|
|
|
|
cache_put_and_wake(c, b);
|
|
|
|
cond_resched();
|
|
}
|
|
lru_iter_end(&it);
|
|
|
|
wake_up(&c->free_buffer_wait);
|
|
dm_bufio_unlock(c);
|
|
|
|
a = xchg(&c->async_write_error, 0);
|
|
f = dm_bufio_issue_flush(c);
|
|
if (a)
|
|
return a;
|
|
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers);
|
|
|
|
/*
|
|
* Use dm-io to send an empty barrier to flush the device.
|
|
*/
|
|
int dm_bufio_issue_flush(struct dm_bufio_client *c)
|
|
{
|
|
struct dm_io_request io_req = {
|
|
.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC,
|
|
.mem.type = DM_IO_KMEM,
|
|
.mem.ptr.addr = NULL,
|
|
.client = c->dm_io,
|
|
};
|
|
struct dm_io_region io_reg = {
|
|
.bdev = c->bdev,
|
|
.sector = 0,
|
|
.count = 0,
|
|
};
|
|
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return -EINVAL;
|
|
|
|
return dm_io(&io_req, 1, &io_reg, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
|
|
|
|
/*
|
|
* Use dm-io to send a discard request to flush the device.
|
|
*/
|
|
int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count)
|
|
{
|
|
struct dm_io_request io_req = {
|
|
.bi_opf = REQ_OP_DISCARD | REQ_SYNC,
|
|
.mem.type = DM_IO_KMEM,
|
|
.mem.ptr.addr = NULL,
|
|
.client = c->dm_io,
|
|
};
|
|
struct dm_io_region io_reg = {
|
|
.bdev = c->bdev,
|
|
.sector = block_to_sector(c, block),
|
|
.count = block_to_sector(c, count),
|
|
};
|
|
|
|
if (WARN_ON_ONCE(dm_bufio_in_request()))
|
|
return -EINVAL; /* discards are optional */
|
|
|
|
return dm_io(&io_req, 1, &io_reg, NULL);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_issue_discard);
|
|
|
|
static bool forget_buffer(struct dm_bufio_client *c, sector_t block)
|
|
{
|
|
struct dm_buffer *b;
|
|
|
|
b = cache_get(&c->cache, block);
|
|
if (b) {
|
|
if (likely(!smp_load_acquire(&b->state))) {
|
|
if (cache_remove(&c->cache, b))
|
|
__free_buffer_wake(b);
|
|
else
|
|
cache_put_and_wake(c, b);
|
|
} else {
|
|
cache_put_and_wake(c, b);
|
|
}
|
|
}
|
|
|
|
return b ? true : false;
|
|
}
|
|
|
|
/*
|
|
* Free the given buffer.
|
|
*
|
|
* This is just a hint, if the buffer is in use or dirty, this function
|
|
* does nothing.
|
|
*/
|
|
void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)
|
|
{
|
|
dm_bufio_lock(c);
|
|
forget_buffer(c, block);
|
|
dm_bufio_unlock(c);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_forget);
|
|
|
|
static enum evict_result idle(struct dm_buffer *b, void *context)
|
|
{
|
|
return b->state ? ER_DONT_EVICT : ER_EVICT;
|
|
}
|
|
|
|
void dm_bufio_forget_buffers(struct dm_bufio_client *c, sector_t block, sector_t n_blocks)
|
|
{
|
|
dm_bufio_lock(c);
|
|
cache_remove_range(&c->cache, block, block + n_blocks, idle, __free_buffer_wake);
|
|
dm_bufio_unlock(c);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_forget_buffers);
|
|
|
|
void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned int n)
|
|
{
|
|
c->minimum_buffers = n;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers);
|
|
|
|
unsigned int dm_bufio_get_block_size(struct dm_bufio_client *c)
|
|
{
|
|
return c->block_size;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
|
|
|
|
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
|
|
{
|
|
sector_t s = bdev_nr_sectors(c->bdev);
|
|
|
|
if (s >= c->start)
|
|
s -= c->start;
|
|
else
|
|
s = 0;
|
|
if (likely(c->sectors_per_block_bits >= 0))
|
|
s >>= c->sectors_per_block_bits;
|
|
else
|
|
sector_div(s, c->block_size >> SECTOR_SHIFT);
|
|
return s;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
|
|
|
|
struct dm_io_client *dm_bufio_get_dm_io_client(struct dm_bufio_client *c)
|
|
{
|
|
return c->dm_io;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_dm_io_client);
|
|
|
|
sector_t dm_bufio_get_block_number(struct dm_buffer *b)
|
|
{
|
|
return b->block;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
|
|
|
|
void *dm_bufio_get_block_data(struct dm_buffer *b)
|
|
{
|
|
return b->data;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
|
|
|
|
void *dm_bufio_get_aux_data(struct dm_buffer *b)
|
|
{
|
|
return b + 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
|
|
|
|
struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b)
|
|
{
|
|
return b->c;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_get_client);
|
|
|
|
static enum it_action warn_leak(struct dm_buffer *b, void *context)
|
|
{
|
|
bool *warned = context;
|
|
|
|
WARN_ON(!(*warned));
|
|
*warned = true;
|
|
DMERR("leaked buffer %llx, hold count %u, list %d",
|
|
(unsigned long long)b->block, atomic_read(&b->hold_count), b->list_mode);
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
stack_trace_print(b->stack_entries, b->stack_len, 1);
|
|
/* mark unclaimed to avoid WARN_ON at end of drop_buffers() */
|
|
atomic_set(&b->hold_count, 0);
|
|
#endif
|
|
return IT_NEXT;
|
|
}
|
|
|
|
static void drop_buffers(struct dm_bufio_client *c)
|
|
{
|
|
int i;
|
|
struct dm_buffer *b;
|
|
|
|
if (WARN_ON(dm_bufio_in_request()))
|
|
return; /* should never happen */
|
|
|
|
/*
|
|
* An optimization so that the buffers are not written one-by-one.
|
|
*/
|
|
dm_bufio_write_dirty_buffers_async(c);
|
|
|
|
dm_bufio_lock(c);
|
|
|
|
while ((b = __get_unclaimed_buffer(c)))
|
|
__free_buffer_wake(b);
|
|
|
|
for (i = 0; i < LIST_SIZE; i++) {
|
|
bool warned = false;
|
|
|
|
cache_iterate(&c->cache, i, warn_leak, &warned);
|
|
}
|
|
|
|
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
|
|
while ((b = __get_unclaimed_buffer(c)))
|
|
__free_buffer_wake(b);
|
|
#endif
|
|
|
|
for (i = 0; i < LIST_SIZE; i++)
|
|
WARN_ON(cache_count(&c->cache, i));
|
|
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
static unsigned long get_retain_buffers(struct dm_bufio_client *c)
|
|
{
|
|
unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes);
|
|
|
|
if (likely(c->sectors_per_block_bits >= 0))
|
|
retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT;
|
|
else
|
|
retain_bytes /= c->block_size;
|
|
|
|
return retain_bytes;
|
|
}
|
|
|
|
static void __scan(struct dm_bufio_client *c)
|
|
{
|
|
int l;
|
|
struct dm_buffer *b;
|
|
unsigned long freed = 0;
|
|
unsigned long retain_target = get_retain_buffers(c);
|
|
unsigned long count = cache_total(&c->cache);
|
|
|
|
for (l = 0; l < LIST_SIZE; l++) {
|
|
while (true) {
|
|
if (count - freed <= retain_target)
|
|
atomic_long_set(&c->need_shrink, 0);
|
|
if (!atomic_long_read(&c->need_shrink))
|
|
break;
|
|
|
|
b = cache_evict(&c->cache, l,
|
|
l == LIST_CLEAN ? is_clean : is_dirty, c);
|
|
if (!b)
|
|
break;
|
|
|
|
__make_buffer_clean(b);
|
|
__free_buffer_wake(b);
|
|
|
|
atomic_long_dec(&c->need_shrink);
|
|
freed++;
|
|
cond_resched();
|
|
}
|
|
}
|
|
}
|
|
|
|
static void shrink_work(struct work_struct *w)
|
|
{
|
|
struct dm_bufio_client *c = container_of(w, struct dm_bufio_client, shrink_work);
|
|
|
|
dm_bufio_lock(c);
|
|
__scan(c);
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
struct dm_bufio_client *c;
|
|
|
|
c = container_of(shrink, struct dm_bufio_client, shrinker);
|
|
atomic_long_add(sc->nr_to_scan, &c->need_shrink);
|
|
queue_work(dm_bufio_wq, &c->shrink_work);
|
|
|
|
return sc->nr_to_scan;
|
|
}
|
|
|
|
static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker);
|
|
unsigned long count = cache_total(&c->cache);
|
|
unsigned long retain_target = get_retain_buffers(c);
|
|
unsigned long queued_for_cleanup = atomic_long_read(&c->need_shrink);
|
|
|
|
if (unlikely(count < retain_target))
|
|
count = 0;
|
|
else
|
|
count -= retain_target;
|
|
|
|
if (unlikely(count < queued_for_cleanup))
|
|
count = 0;
|
|
else
|
|
count -= queued_for_cleanup;
|
|
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* Create the buffering interface
|
|
*/
|
|
struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned int block_size,
|
|
unsigned int reserved_buffers, unsigned int aux_size,
|
|
void (*alloc_callback)(struct dm_buffer *),
|
|
void (*write_callback)(struct dm_buffer *),
|
|
unsigned int flags)
|
|
{
|
|
int r;
|
|
unsigned int num_locks;
|
|
struct dm_bufio_client *c;
|
|
char slab_name[27];
|
|
|
|
if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) {
|
|
DMERR("%s: block size not specified or is not multiple of 512b", __func__);
|
|
r = -EINVAL;
|
|
goto bad_client;
|
|
}
|
|
|
|
num_locks = dm_num_hash_locks();
|
|
c = kzalloc(sizeof(*c) + (num_locks * sizeof(struct buffer_tree)), GFP_KERNEL);
|
|
if (!c) {
|
|
r = -ENOMEM;
|
|
goto bad_client;
|
|
}
|
|
cache_init(&c->cache, num_locks);
|
|
|
|
c->bdev = bdev;
|
|
c->block_size = block_size;
|
|
if (is_power_of_2(block_size))
|
|
c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
|
|
else
|
|
c->sectors_per_block_bits = -1;
|
|
|
|
c->alloc_callback = alloc_callback;
|
|
c->write_callback = write_callback;
|
|
|
|
if (flags & DM_BUFIO_CLIENT_NO_SLEEP) {
|
|
c->no_sleep = true;
|
|
static_branch_inc(&no_sleep_enabled);
|
|
}
|
|
|
|
mutex_init(&c->lock);
|
|
spin_lock_init(&c->spinlock);
|
|
INIT_LIST_HEAD(&c->reserved_buffers);
|
|
c->need_reserved_buffers = reserved_buffers;
|
|
|
|
dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS);
|
|
|
|
init_waitqueue_head(&c->free_buffer_wait);
|
|
c->async_write_error = 0;
|
|
|
|
c->dm_io = dm_io_client_create();
|
|
if (IS_ERR(c->dm_io)) {
|
|
r = PTR_ERR(c->dm_io);
|
|
goto bad_dm_io;
|
|
}
|
|
|
|
if (block_size <= KMALLOC_MAX_SIZE &&
|
|
(block_size < PAGE_SIZE || !is_power_of_2(block_size))) {
|
|
unsigned int align = min(1U << __ffs(block_size), (unsigned int)PAGE_SIZE);
|
|
|
|
snprintf(slab_name, sizeof(slab_name), "dm_bufio_cache-%u", block_size);
|
|
c->slab_cache = kmem_cache_create(slab_name, block_size, align,
|
|
SLAB_RECLAIM_ACCOUNT, NULL);
|
|
if (!c->slab_cache) {
|
|
r = -ENOMEM;
|
|
goto bad;
|
|
}
|
|
}
|
|
if (aux_size)
|
|
snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer-%u", aux_size);
|
|
else
|
|
snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer");
|
|
c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size,
|
|
0, SLAB_RECLAIM_ACCOUNT, NULL);
|
|
if (!c->slab_buffer) {
|
|
r = -ENOMEM;
|
|
goto bad;
|
|
}
|
|
|
|
while (c->need_reserved_buffers) {
|
|
struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL);
|
|
|
|
if (!b) {
|
|
r = -ENOMEM;
|
|
goto bad;
|
|
}
|
|
__free_buffer_wake(b);
|
|
}
|
|
|
|
INIT_WORK(&c->shrink_work, shrink_work);
|
|
atomic_long_set(&c->need_shrink, 0);
|
|
|
|
c->shrinker.count_objects = dm_bufio_shrink_count;
|
|
c->shrinker.scan_objects = dm_bufio_shrink_scan;
|
|
c->shrinker.seeks = 1;
|
|
c->shrinker.batch = 0;
|
|
r = register_shrinker(&c->shrinker, "dm-bufio:(%u:%u)",
|
|
MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));
|
|
if (r)
|
|
goto bad;
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
dm_bufio_client_count++;
|
|
list_add(&c->client_list, &dm_bufio_all_clients);
|
|
__cache_size_refresh();
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
|
|
return c;
|
|
|
|
bad:
|
|
while (!list_empty(&c->reserved_buffers)) {
|
|
struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next);
|
|
|
|
list_del(&b->lru.list);
|
|
free_buffer(b);
|
|
}
|
|
kmem_cache_destroy(c->slab_cache);
|
|
kmem_cache_destroy(c->slab_buffer);
|
|
dm_io_client_destroy(c->dm_io);
|
|
bad_dm_io:
|
|
mutex_destroy(&c->lock);
|
|
if (c->no_sleep)
|
|
static_branch_dec(&no_sleep_enabled);
|
|
kfree(c);
|
|
bad_client:
|
|
return ERR_PTR(r);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_client_create);
|
|
|
|
/*
|
|
* Free the buffering interface.
|
|
* It is required that there are no references on any buffers.
|
|
*/
|
|
void dm_bufio_client_destroy(struct dm_bufio_client *c)
|
|
{
|
|
unsigned int i;
|
|
|
|
drop_buffers(c);
|
|
|
|
unregister_shrinker(&c->shrinker);
|
|
flush_work(&c->shrink_work);
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
|
|
list_del(&c->client_list);
|
|
dm_bufio_client_count--;
|
|
__cache_size_refresh();
|
|
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
|
|
WARN_ON(c->need_reserved_buffers);
|
|
|
|
while (!list_empty(&c->reserved_buffers)) {
|
|
struct dm_buffer *b = list_to_buffer(c->reserved_buffers.next);
|
|
|
|
list_del(&b->lru.list);
|
|
free_buffer(b);
|
|
}
|
|
|
|
for (i = 0; i < LIST_SIZE; i++)
|
|
if (cache_count(&c->cache, i))
|
|
DMERR("leaked buffer count %d: %lu", i, cache_count(&c->cache, i));
|
|
|
|
for (i = 0; i < LIST_SIZE; i++)
|
|
WARN_ON(cache_count(&c->cache, i));
|
|
|
|
cache_destroy(&c->cache);
|
|
kmem_cache_destroy(c->slab_cache);
|
|
kmem_cache_destroy(c->slab_buffer);
|
|
dm_io_client_destroy(c->dm_io);
|
|
mutex_destroy(&c->lock);
|
|
if (c->no_sleep)
|
|
static_branch_dec(&no_sleep_enabled);
|
|
kfree(c);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
|
|
|
|
void dm_bufio_client_reset(struct dm_bufio_client *c)
|
|
{
|
|
drop_buffers(c);
|
|
flush_work(&c->shrink_work);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_client_reset);
|
|
|
|
void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start)
|
|
{
|
|
c->start = start;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset);
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
static unsigned int get_max_age_hz(void)
|
|
{
|
|
unsigned int max_age = READ_ONCE(dm_bufio_max_age);
|
|
|
|
if (max_age > UINT_MAX / HZ)
|
|
max_age = UINT_MAX / HZ;
|
|
|
|
return max_age * HZ;
|
|
}
|
|
|
|
static bool older_than(struct dm_buffer *b, unsigned long age_hz)
|
|
{
|
|
return time_after_eq(jiffies, READ_ONCE(b->last_accessed) + age_hz);
|
|
}
|
|
|
|
struct evict_params {
|
|
gfp_t gfp;
|
|
unsigned long age_hz;
|
|
|
|
/*
|
|
* This gets updated with the largest last_accessed (ie. most
|
|
* recently used) of the evicted buffers. It will not be reinitialised
|
|
* by __evict_many(), so you can use it across multiple invocations.
|
|
*/
|
|
unsigned long last_accessed;
|
|
};
|
|
|
|
/*
|
|
* We may not be able to evict this buffer if IO pending or the client
|
|
* is still using it.
|
|
*
|
|
* And if GFP_NOFS is used, we must not do any I/O because we hold
|
|
* dm_bufio_clients_lock and we would risk deadlock if the I/O gets
|
|
* rerouted to different bufio client.
|
|
*/
|
|
static enum evict_result select_for_evict(struct dm_buffer *b, void *context)
|
|
{
|
|
struct evict_params *params = context;
|
|
|
|
if (!(params->gfp & __GFP_FS) ||
|
|
(static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) {
|
|
if (test_bit_acquire(B_READING, &b->state) ||
|
|
test_bit(B_WRITING, &b->state) ||
|
|
test_bit(B_DIRTY, &b->state))
|
|
return ER_DONT_EVICT;
|
|
}
|
|
|
|
return older_than(b, params->age_hz) ? ER_EVICT : ER_STOP;
|
|
}
|
|
|
|
static unsigned long __evict_many(struct dm_bufio_client *c,
|
|
struct evict_params *params,
|
|
int list_mode, unsigned long max_count)
|
|
{
|
|
unsigned long count;
|
|
unsigned long last_accessed;
|
|
struct dm_buffer *b;
|
|
|
|
for (count = 0; count < max_count; count++) {
|
|
b = cache_evict(&c->cache, list_mode, select_for_evict, params);
|
|
if (!b)
|
|
break;
|
|
|
|
last_accessed = READ_ONCE(b->last_accessed);
|
|
if (time_after_eq(params->last_accessed, last_accessed))
|
|
params->last_accessed = last_accessed;
|
|
|
|
__make_buffer_clean(b);
|
|
__free_buffer_wake(b);
|
|
|
|
cond_resched();
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
static void evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)
|
|
{
|
|
struct evict_params params = {.gfp = 0, .age_hz = age_hz, .last_accessed = 0};
|
|
unsigned long retain = get_retain_buffers(c);
|
|
unsigned long count;
|
|
LIST_HEAD(write_list);
|
|
|
|
dm_bufio_lock(c);
|
|
|
|
__check_watermark(c, &write_list);
|
|
if (unlikely(!list_empty(&write_list))) {
|
|
dm_bufio_unlock(c);
|
|
__flush_write_list(&write_list);
|
|
dm_bufio_lock(c);
|
|
}
|
|
|
|
count = cache_total(&c->cache);
|
|
if (count > retain)
|
|
__evict_many(c, ¶ms, LIST_CLEAN, count - retain);
|
|
|
|
dm_bufio_unlock(c);
|
|
}
|
|
|
|
static void cleanup_old_buffers(void)
|
|
{
|
|
unsigned long max_age_hz = get_max_age_hz();
|
|
struct dm_bufio_client *c;
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
|
|
__cache_size_refresh();
|
|
|
|
list_for_each_entry(c, &dm_bufio_all_clients, client_list)
|
|
evict_old_buffers(c, max_age_hz);
|
|
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
}
|
|
|
|
static void work_fn(struct work_struct *w)
|
|
{
|
|
cleanup_old_buffers();
|
|
|
|
queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work,
|
|
DM_BUFIO_WORK_TIMER_SECS * HZ);
|
|
}
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Global cleanup tries to evict the oldest buffers from across _all_
|
|
* the clients. It does this by repeatedly evicting a few buffers from
|
|
* the client that holds the oldest buffer. It's approximate, but hopefully
|
|
* good enough.
|
|
*/
|
|
static struct dm_bufio_client *__pop_client(void)
|
|
{
|
|
struct list_head *h;
|
|
|
|
if (list_empty(&dm_bufio_all_clients))
|
|
return NULL;
|
|
|
|
h = dm_bufio_all_clients.next;
|
|
list_del(h);
|
|
return container_of(h, struct dm_bufio_client, client_list);
|
|
}
|
|
|
|
/*
|
|
* Inserts the client in the global client list based on its
|
|
* 'oldest_buffer' field.
|
|
*/
|
|
static void __insert_client(struct dm_bufio_client *new_client)
|
|
{
|
|
struct dm_bufio_client *c;
|
|
struct list_head *h = dm_bufio_all_clients.next;
|
|
|
|
while (h != &dm_bufio_all_clients) {
|
|
c = container_of(h, struct dm_bufio_client, client_list);
|
|
if (time_after_eq(c->oldest_buffer, new_client->oldest_buffer))
|
|
break;
|
|
h = h->next;
|
|
}
|
|
|
|
list_add_tail(&new_client->client_list, h);
|
|
}
|
|
|
|
static unsigned long __evict_a_few(unsigned long nr_buffers)
|
|
{
|
|
unsigned long count;
|
|
struct dm_bufio_client *c;
|
|
struct evict_params params = {
|
|
.gfp = GFP_KERNEL,
|
|
.age_hz = 0,
|
|
/* set to jiffies in case there are no buffers in this client */
|
|
.last_accessed = jiffies
|
|
};
|
|
|
|
c = __pop_client();
|
|
if (!c)
|
|
return 0;
|
|
|
|
dm_bufio_lock(c);
|
|
count = __evict_many(c, ¶ms, LIST_CLEAN, nr_buffers);
|
|
dm_bufio_unlock(c);
|
|
|
|
if (count)
|
|
c->oldest_buffer = params.last_accessed;
|
|
__insert_client(c);
|
|
|
|
return count;
|
|
}
|
|
|
|
static void check_watermarks(void)
|
|
{
|
|
LIST_HEAD(write_list);
|
|
struct dm_bufio_client *c;
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
list_for_each_entry(c, &dm_bufio_all_clients, client_list) {
|
|
dm_bufio_lock(c);
|
|
__check_watermark(c, &write_list);
|
|
dm_bufio_unlock(c);
|
|
}
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
|
|
__flush_write_list(&write_list);
|
|
}
|
|
|
|
static void evict_old(void)
|
|
{
|
|
unsigned long threshold = dm_bufio_cache_size -
|
|
dm_bufio_cache_size / DM_BUFIO_LOW_WATERMARK_RATIO;
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
while (dm_bufio_current_allocated > threshold) {
|
|
if (!__evict_a_few(64))
|
|
break;
|
|
cond_resched();
|
|
}
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
}
|
|
|
|
static void do_global_cleanup(struct work_struct *w)
|
|
{
|
|
check_watermarks();
|
|
evict_old();
|
|
}
|
|
|
|
/*
|
|
*--------------------------------------------------------------
|
|
* Module setup
|
|
*--------------------------------------------------------------
|
|
*/
|
|
|
|
/*
|
|
* This is called only once for the whole dm_bufio module.
|
|
* It initializes memory limit.
|
|
*/
|
|
static int __init dm_bufio_init(void)
|
|
{
|
|
__u64 mem;
|
|
|
|
dm_bufio_allocated_kmem_cache = 0;
|
|
dm_bufio_allocated_get_free_pages = 0;
|
|
dm_bufio_allocated_vmalloc = 0;
|
|
dm_bufio_current_allocated = 0;
|
|
|
|
mem = (__u64)mult_frac(totalram_pages() - totalhigh_pages(),
|
|
DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT;
|
|
|
|
if (mem > ULONG_MAX)
|
|
mem = ULONG_MAX;
|
|
|
|
#ifdef CONFIG_MMU
|
|
if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100))
|
|
mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100);
|
|
#endif
|
|
|
|
dm_bufio_default_cache_size = mem;
|
|
|
|
mutex_lock(&dm_bufio_clients_lock);
|
|
__cache_size_refresh();
|
|
mutex_unlock(&dm_bufio_clients_lock);
|
|
|
|
dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0);
|
|
if (!dm_bufio_wq)
|
|
return -ENOMEM;
|
|
|
|
INIT_DELAYED_WORK(&dm_bufio_cleanup_old_work, work_fn);
|
|
INIT_WORK(&dm_bufio_replacement_work, do_global_cleanup);
|
|
queue_delayed_work(dm_bufio_wq, &dm_bufio_cleanup_old_work,
|
|
DM_BUFIO_WORK_TIMER_SECS * HZ);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This is called once when unloading the dm_bufio module.
|
|
*/
|
|
static void __exit dm_bufio_exit(void)
|
|
{
|
|
int bug = 0;
|
|
|
|
cancel_delayed_work_sync(&dm_bufio_cleanup_old_work);
|
|
destroy_workqueue(dm_bufio_wq);
|
|
|
|
if (dm_bufio_client_count) {
|
|
DMCRIT("%s: dm_bufio_client_count leaked: %d",
|
|
__func__, dm_bufio_client_count);
|
|
bug = 1;
|
|
}
|
|
|
|
if (dm_bufio_current_allocated) {
|
|
DMCRIT("%s: dm_bufio_current_allocated leaked: %lu",
|
|
__func__, dm_bufio_current_allocated);
|
|
bug = 1;
|
|
}
|
|
|
|
if (dm_bufio_allocated_get_free_pages) {
|
|
DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu",
|
|
__func__, dm_bufio_allocated_get_free_pages);
|
|
bug = 1;
|
|
}
|
|
|
|
if (dm_bufio_allocated_vmalloc) {
|
|
DMCRIT("%s: dm_bufio_vmalloc leaked: %lu",
|
|
__func__, dm_bufio_allocated_vmalloc);
|
|
bug = 1;
|
|
}
|
|
|
|
WARN_ON(bug); /* leaks are not worth crashing the system */
|
|
}
|
|
|
|
module_init(dm_bufio_init)
|
|
module_exit(dm_bufio_exit)
|
|
|
|
module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, 0644);
|
|
MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache");
|
|
|
|
module_param_named(max_age_seconds, dm_bufio_max_age, uint, 0644);
|
|
MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");
|
|
|
|
module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, 0644);
|
|
MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");
|
|
|
|
module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, 0644);
|
|
MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
|
|
|
|
module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, 0444);
|
|
MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
|
|
|
|
module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, 0444);
|
|
MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");
|
|
|
|
module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, 0444);
|
|
MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc");
|
|
|
|
module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, 0444);
|
|
MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache");
|
|
|
|
MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
|
|
MODULE_DESCRIPTION(DM_NAME " buffered I/O library");
|
|
MODULE_LICENSE("GPL");
|