linux/drivers/md/dm-writecache.c
Mike Snitzer 636be4241b dm: bump version of core and various targets
Changes made during the 5.6 cycle warrant bumping the version number
for DM core and the targets modified by this commit.

It should be noted that dm-thin, dm-crypt and dm-raid already had
their target version bumped during the 5.6 merge window.

Signed-off-by; Mike Snitzer <snitzer@redhat.com>
2020-03-03 11:10:21 -05:00

2361 lines
58 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018 Red Hat. All rights reserved.
*
* This file is released under the GPL.
*/
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/kthread.h>
#include <linux/dm-io.h>
#include <linux/dm-kcopyd.h>
#include <linux/dax.h>
#include <linux/pfn_t.h>
#include <linux/libnvdimm.h>
#define DM_MSG_PREFIX "writecache"
#define HIGH_WATERMARK 50
#define LOW_WATERMARK 45
#define MAX_WRITEBACK_JOBS 0
#define ENDIO_LATENCY 16
#define WRITEBACK_LATENCY 64
#define AUTOCOMMIT_BLOCKS_SSD 65536
#define AUTOCOMMIT_BLOCKS_PMEM 64
#define AUTOCOMMIT_MSEC 1000
#define BITMAP_GRANULARITY 65536
#if BITMAP_GRANULARITY < PAGE_SIZE
#undef BITMAP_GRANULARITY
#define BITMAP_GRANULARITY PAGE_SIZE
#endif
#if IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API) && IS_ENABLED(CONFIG_DAX_DRIVER)
#define DM_WRITECACHE_HAS_PMEM
#endif
#ifdef DM_WRITECACHE_HAS_PMEM
#define pmem_assign(dest, src) \
do { \
typeof(dest) uniq = (src); \
memcpy_flushcache(&(dest), &uniq, sizeof(dest)); \
} while (0)
#else
#define pmem_assign(dest, src) ((dest) = (src))
#endif
#if defined(__HAVE_ARCH_MEMCPY_MCSAFE) && defined(DM_WRITECACHE_HAS_PMEM)
#define DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
#endif
#define MEMORY_SUPERBLOCK_MAGIC 0x23489321
#define MEMORY_SUPERBLOCK_VERSION 1
struct wc_memory_entry {
__le64 original_sector;
__le64 seq_count;
};
struct wc_memory_superblock {
union {
struct {
__le32 magic;
__le32 version;
__le32 block_size;
__le32 pad;
__le64 n_blocks;
__le64 seq_count;
};
__le64 padding[8];
};
struct wc_memory_entry entries[0];
};
struct wc_entry {
struct rb_node rb_node;
struct list_head lru;
unsigned short wc_list_contiguous;
bool write_in_progress
#if BITS_PER_LONG == 64
:1
#endif
;
unsigned long index
#if BITS_PER_LONG == 64
:47
#endif
;
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
uint64_t original_sector;
uint64_t seq_count;
#endif
};
#ifdef DM_WRITECACHE_HAS_PMEM
#define WC_MODE_PMEM(wc) ((wc)->pmem_mode)
#define WC_MODE_FUA(wc) ((wc)->writeback_fua)
#else
#define WC_MODE_PMEM(wc) false
#define WC_MODE_FUA(wc) false
#endif
#define WC_MODE_SORT_FREELIST(wc) (!WC_MODE_PMEM(wc))
struct dm_writecache {
struct mutex lock;
struct list_head lru;
union {
struct list_head freelist;
struct {
struct rb_root freetree;
struct wc_entry *current_free;
};
};
struct rb_root tree;
size_t freelist_size;
size_t writeback_size;
size_t freelist_high_watermark;
size_t freelist_low_watermark;
unsigned uncommitted_blocks;
unsigned autocommit_blocks;
unsigned max_writeback_jobs;
int error;
unsigned long autocommit_jiffies;
struct timer_list autocommit_timer;
struct wait_queue_head freelist_wait;
atomic_t bio_in_progress[2];
struct wait_queue_head bio_in_progress_wait[2];
struct dm_target *ti;
struct dm_dev *dev;
struct dm_dev *ssd_dev;
sector_t start_sector;
void *memory_map;
uint64_t memory_map_size;
size_t metadata_sectors;
size_t n_blocks;
uint64_t seq_count;
void *block_start;
struct wc_entry *entries;
unsigned block_size;
unsigned char block_size_bits;
bool pmem_mode:1;
bool writeback_fua:1;
bool overwrote_committed:1;
bool memory_vmapped:1;
bool high_wm_percent_set:1;
bool low_wm_percent_set:1;
bool max_writeback_jobs_set:1;
bool autocommit_blocks_set:1;
bool autocommit_time_set:1;
bool writeback_fua_set:1;
bool flush_on_suspend:1;
unsigned writeback_all;
struct workqueue_struct *writeback_wq;
struct work_struct writeback_work;
struct work_struct flush_work;
struct dm_io_client *dm_io;
raw_spinlock_t endio_list_lock;
struct list_head endio_list;
struct task_struct *endio_thread;
struct task_struct *flush_thread;
struct bio_list flush_list;
struct dm_kcopyd_client *dm_kcopyd;
unsigned long *dirty_bitmap;
unsigned dirty_bitmap_size;
struct bio_set bio_set;
mempool_t copy_pool;
};
#define WB_LIST_INLINE 16
struct writeback_struct {
struct list_head endio_entry;
struct dm_writecache *wc;
struct wc_entry **wc_list;
unsigned wc_list_n;
struct wc_entry *wc_list_inline[WB_LIST_INLINE];
struct bio bio;
};
struct copy_struct {
struct list_head endio_entry;
struct dm_writecache *wc;
struct wc_entry *e;
unsigned n_entries;
int error;
};
DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(dm_writecache_throttle,
"A percentage of time allocated for data copying");
static void wc_lock(struct dm_writecache *wc)
{
mutex_lock(&wc->lock);
}
static void wc_unlock(struct dm_writecache *wc)
{
mutex_unlock(&wc->lock);
}
#ifdef DM_WRITECACHE_HAS_PMEM
static int persistent_memory_claim(struct dm_writecache *wc)
{
int r;
loff_t s;
long p, da;
pfn_t pfn;
int id;
struct page **pages;
wc->memory_vmapped = false;
if (!wc->ssd_dev->dax_dev) {
r = -EOPNOTSUPP;
goto err1;
}
s = wc->memory_map_size;
p = s >> PAGE_SHIFT;
if (!p) {
r = -EINVAL;
goto err1;
}
if (p != s >> PAGE_SHIFT) {
r = -EOVERFLOW;
goto err1;
}
id = dax_read_lock();
da = dax_direct_access(wc->ssd_dev->dax_dev, 0, p, &wc->memory_map, &pfn);
if (da < 0) {
wc->memory_map = NULL;
r = da;
goto err2;
}
if (!pfn_t_has_page(pfn)) {
wc->memory_map = NULL;
r = -EOPNOTSUPP;
goto err2;
}
if (da != p) {
long i;
wc->memory_map = NULL;
pages = kvmalloc_array(p, sizeof(struct page *), GFP_KERNEL);
if (!pages) {
r = -ENOMEM;
goto err2;
}
i = 0;
do {
long daa;
daa = dax_direct_access(wc->ssd_dev->dax_dev, i, p - i,
NULL, &pfn);
if (daa <= 0) {
r = daa ? daa : -EINVAL;
goto err3;
}
if (!pfn_t_has_page(pfn)) {
r = -EOPNOTSUPP;
goto err3;
}
while (daa-- && i < p) {
pages[i++] = pfn_t_to_page(pfn);
pfn.val++;
}
} while (i < p);
wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
if (!wc->memory_map) {
r = -ENOMEM;
goto err3;
}
kvfree(pages);
wc->memory_vmapped = true;
}
dax_read_unlock(id);
wc->memory_map += (size_t)wc->start_sector << SECTOR_SHIFT;
wc->memory_map_size -= (size_t)wc->start_sector << SECTOR_SHIFT;
return 0;
err3:
kvfree(pages);
err2:
dax_read_unlock(id);
err1:
return r;
}
#else
static int persistent_memory_claim(struct dm_writecache *wc)
{
BUG();
}
#endif
static void persistent_memory_release(struct dm_writecache *wc)
{
if (wc->memory_vmapped)
vunmap(wc->memory_map - ((size_t)wc->start_sector << SECTOR_SHIFT));
}
static struct page *persistent_memory_page(void *addr)
{
if (is_vmalloc_addr(addr))
return vmalloc_to_page(addr);
else
return virt_to_page(addr);
}
static unsigned persistent_memory_page_offset(void *addr)
{
return (unsigned long)addr & (PAGE_SIZE - 1);
}
static void persistent_memory_flush_cache(void *ptr, size_t size)
{
if (is_vmalloc_addr(ptr))
flush_kernel_vmap_range(ptr, size);
}
static void persistent_memory_invalidate_cache(void *ptr, size_t size)
{
if (is_vmalloc_addr(ptr))
invalidate_kernel_vmap_range(ptr, size);
}
static struct wc_memory_superblock *sb(struct dm_writecache *wc)
{
return wc->memory_map;
}
static struct wc_memory_entry *memory_entry(struct dm_writecache *wc, struct wc_entry *e)
{
return &sb(wc)->entries[e->index];
}
static void *memory_data(struct dm_writecache *wc, struct wc_entry *e)
{
return (char *)wc->block_start + (e->index << wc->block_size_bits);
}
static sector_t cache_sector(struct dm_writecache *wc, struct wc_entry *e)
{
return wc->start_sector + wc->metadata_sectors +
((sector_t)e->index << (wc->block_size_bits - SECTOR_SHIFT));
}
static uint64_t read_original_sector(struct dm_writecache *wc, struct wc_entry *e)
{
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
return e->original_sector;
#else
return le64_to_cpu(memory_entry(wc, e)->original_sector);
#endif
}
static uint64_t read_seq_count(struct dm_writecache *wc, struct wc_entry *e)
{
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
return e->seq_count;
#else
return le64_to_cpu(memory_entry(wc, e)->seq_count);
#endif
}
static void clear_seq_count(struct dm_writecache *wc, struct wc_entry *e)
{
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
e->seq_count = -1;
#endif
pmem_assign(memory_entry(wc, e)->seq_count, cpu_to_le64(-1));
}
static void write_original_sector_seq_count(struct dm_writecache *wc, struct wc_entry *e,
uint64_t original_sector, uint64_t seq_count)
{
struct wc_memory_entry me;
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
e->original_sector = original_sector;
e->seq_count = seq_count;
#endif
me.original_sector = cpu_to_le64(original_sector);
me.seq_count = cpu_to_le64(seq_count);
pmem_assign(*memory_entry(wc, e), me);
}
#define writecache_error(wc, err, msg, arg...) \
do { \
if (!cmpxchg(&(wc)->error, 0, err)) \
DMERR(msg, ##arg); \
wake_up(&(wc)->freelist_wait); \
} while (0)
#define writecache_has_error(wc) (unlikely(READ_ONCE((wc)->error)))
static void writecache_flush_all_metadata(struct dm_writecache *wc)
{
if (!WC_MODE_PMEM(wc))
memset(wc->dirty_bitmap, -1, wc->dirty_bitmap_size);
}
static void writecache_flush_region(struct dm_writecache *wc, void *ptr, size_t size)
{
if (!WC_MODE_PMEM(wc))
__set_bit(((char *)ptr - (char *)wc->memory_map) / BITMAP_GRANULARITY,
wc->dirty_bitmap);
}
static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev);
struct io_notify {
struct dm_writecache *wc;
struct completion c;
atomic_t count;
};
static void writecache_notify_io(unsigned long error, void *context)
{
struct io_notify *endio = context;
if (unlikely(error != 0))
writecache_error(endio->wc, -EIO, "error writing metadata");
BUG_ON(atomic_read(&endio->count) <= 0);
if (atomic_dec_and_test(&endio->count))
complete(&endio->c);
}
static void writecache_wait_for_ios(struct dm_writecache *wc, int direction)
{
wait_event(wc->bio_in_progress_wait[direction],
!atomic_read(&wc->bio_in_progress[direction]));
}
static void ssd_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
{
struct dm_io_region region;
struct dm_io_request req;
struct io_notify endio = {
wc,
COMPLETION_INITIALIZER_ONSTACK(endio.c),
ATOMIC_INIT(1),
};
unsigned bitmap_bits = wc->dirty_bitmap_size * 8;
unsigned i = 0;
while (1) {
unsigned j;
i = find_next_bit(wc->dirty_bitmap, bitmap_bits, i);
if (unlikely(i == bitmap_bits))
break;
j = find_next_zero_bit(wc->dirty_bitmap, bitmap_bits, i);
region.bdev = wc->ssd_dev->bdev;
region.sector = (sector_t)i * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
region.count = (sector_t)(j - i) * (BITMAP_GRANULARITY >> SECTOR_SHIFT);
if (unlikely(region.sector >= wc->metadata_sectors))
break;
if (unlikely(region.sector + region.count > wc->metadata_sectors))
region.count = wc->metadata_sectors - region.sector;
region.sector += wc->start_sector;
atomic_inc(&endio.count);
req.bi_op = REQ_OP_WRITE;
req.bi_op_flags = REQ_SYNC;
req.mem.type = DM_IO_VMA;
req.mem.ptr.vma = (char *)wc->memory_map + (size_t)i * BITMAP_GRANULARITY;
req.client = wc->dm_io;
req.notify.fn = writecache_notify_io;
req.notify.context = &endio;
/* writing via async dm-io (implied by notify.fn above) won't return an error */
(void) dm_io(&req, 1, &region, NULL);
i = j;
}
writecache_notify_io(0, &endio);
wait_for_completion_io(&endio.c);
if (wait_for_ios)
writecache_wait_for_ios(wc, WRITE);
writecache_disk_flush(wc, wc->ssd_dev);
memset(wc->dirty_bitmap, 0, wc->dirty_bitmap_size);
}
static void writecache_commit_flushed(struct dm_writecache *wc, bool wait_for_ios)
{
if (WC_MODE_PMEM(wc))
wmb();
else
ssd_commit_flushed(wc, wait_for_ios);
}
static void writecache_disk_flush(struct dm_writecache *wc, struct dm_dev *dev)
{
int r;
struct dm_io_region region;
struct dm_io_request req;
region.bdev = dev->bdev;
region.sector = 0;
region.count = 0;
req.bi_op = REQ_OP_WRITE;
req.bi_op_flags = REQ_PREFLUSH;
req.mem.type = DM_IO_KMEM;
req.mem.ptr.addr = NULL;
req.client = wc->dm_io;
req.notify.fn = NULL;
r = dm_io(&req, 1, &region, NULL);
if (unlikely(r))
writecache_error(wc, r, "error flushing metadata: %d", r);
}
#define WFE_RETURN_FOLLOWING 1
#define WFE_LOWEST_SEQ 2
static struct wc_entry *writecache_find_entry(struct dm_writecache *wc,
uint64_t block, int flags)
{
struct wc_entry *e;
struct rb_node *node = wc->tree.rb_node;
if (unlikely(!node))
return NULL;
while (1) {
e = container_of(node, struct wc_entry, rb_node);
if (read_original_sector(wc, e) == block)
break;
node = (read_original_sector(wc, e) >= block ?
e->rb_node.rb_left : e->rb_node.rb_right);
if (unlikely(!node)) {
if (!(flags & WFE_RETURN_FOLLOWING))
return NULL;
if (read_original_sector(wc, e) >= block) {
return e;
} else {
node = rb_next(&e->rb_node);
if (unlikely(!node))
return NULL;
e = container_of(node, struct wc_entry, rb_node);
return e;
}
}
}
while (1) {
struct wc_entry *e2;
if (flags & WFE_LOWEST_SEQ)
node = rb_prev(&e->rb_node);
else
node = rb_next(&e->rb_node);
if (unlikely(!node))
return e;
e2 = container_of(node, struct wc_entry, rb_node);
if (read_original_sector(wc, e2) != block)
return e;
e = e2;
}
}
static void writecache_insert_entry(struct dm_writecache *wc, struct wc_entry *ins)
{
struct wc_entry *e;
struct rb_node **node = &wc->tree.rb_node, *parent = NULL;
while (*node) {
e = container_of(*node, struct wc_entry, rb_node);
parent = &e->rb_node;
if (read_original_sector(wc, e) > read_original_sector(wc, ins))
node = &parent->rb_left;
else
node = &parent->rb_right;
}
rb_link_node(&ins->rb_node, parent, node);
rb_insert_color(&ins->rb_node, &wc->tree);
list_add(&ins->lru, &wc->lru);
}
static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e)
{
list_del(&e->lru);
rb_erase(&e->rb_node, &wc->tree);
}
static void writecache_add_to_freelist(struct dm_writecache *wc, struct wc_entry *e)
{
if (WC_MODE_SORT_FREELIST(wc)) {
struct rb_node **node = &wc->freetree.rb_node, *parent = NULL;
if (unlikely(!*node))
wc->current_free = e;
while (*node) {
parent = *node;
if (&e->rb_node < *node)
node = &parent->rb_left;
else
node = &parent->rb_right;
}
rb_link_node(&e->rb_node, parent, node);
rb_insert_color(&e->rb_node, &wc->freetree);
} else {
list_add_tail(&e->lru, &wc->freelist);
}
wc->freelist_size++;
}
static inline void writecache_verify_watermark(struct dm_writecache *wc)
{
if (unlikely(wc->freelist_size + wc->writeback_size <= wc->freelist_high_watermark))
queue_work(wc->writeback_wq, &wc->writeback_work);
}
static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector)
{
struct wc_entry *e;
if (WC_MODE_SORT_FREELIST(wc)) {
struct rb_node *next;
if (unlikely(!wc->current_free))
return NULL;
e = wc->current_free;
if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
return NULL;
next = rb_next(&e->rb_node);
rb_erase(&e->rb_node, &wc->freetree);
if (unlikely(!next))
next = rb_first(&wc->freetree);
wc->current_free = next ? container_of(next, struct wc_entry, rb_node) : NULL;
} else {
if (unlikely(list_empty(&wc->freelist)))
return NULL;
e = container_of(wc->freelist.next, struct wc_entry, lru);
if (expected_sector != (sector_t)-1 && unlikely(cache_sector(wc, e) != expected_sector))
return NULL;
list_del(&e->lru);
}
wc->freelist_size--;
writecache_verify_watermark(wc);
return e;
}
static void writecache_free_entry(struct dm_writecache *wc, struct wc_entry *e)
{
writecache_unlink(wc, e);
writecache_add_to_freelist(wc, e);
clear_seq_count(wc, e);
writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
if (unlikely(waitqueue_active(&wc->freelist_wait)))
wake_up(&wc->freelist_wait);
}
static void writecache_wait_on_freelist(struct dm_writecache *wc)
{
DEFINE_WAIT(wait);
prepare_to_wait(&wc->freelist_wait, &wait, TASK_UNINTERRUPTIBLE);
wc_unlock(wc);
io_schedule();
finish_wait(&wc->freelist_wait, &wait);
wc_lock(wc);
}
static void writecache_poison_lists(struct dm_writecache *wc)
{
/*
* Catch incorrect access to these values while the device is suspended.
*/
memset(&wc->tree, -1, sizeof wc->tree);
wc->lru.next = LIST_POISON1;
wc->lru.prev = LIST_POISON2;
wc->freelist.next = LIST_POISON1;
wc->freelist.prev = LIST_POISON2;
}
static void writecache_flush_entry(struct dm_writecache *wc, struct wc_entry *e)
{
writecache_flush_region(wc, memory_entry(wc, e), sizeof(struct wc_memory_entry));
if (WC_MODE_PMEM(wc))
writecache_flush_region(wc, memory_data(wc, e), wc->block_size);
}
static bool writecache_entry_is_committed(struct dm_writecache *wc, struct wc_entry *e)
{
return read_seq_count(wc, e) < wc->seq_count;
}
static void writecache_flush(struct dm_writecache *wc)
{
struct wc_entry *e, *e2;
bool need_flush_after_free;
wc->uncommitted_blocks = 0;
del_timer(&wc->autocommit_timer);
if (list_empty(&wc->lru))
return;
e = container_of(wc->lru.next, struct wc_entry, lru);
if (writecache_entry_is_committed(wc, e)) {
if (wc->overwrote_committed) {
writecache_wait_for_ios(wc, WRITE);
writecache_disk_flush(wc, wc->ssd_dev);
wc->overwrote_committed = false;
}
return;
}
while (1) {
writecache_flush_entry(wc, e);
if (unlikely(e->lru.next == &wc->lru))
break;
e2 = container_of(e->lru.next, struct wc_entry, lru);
if (writecache_entry_is_committed(wc, e2))
break;
e = e2;
cond_resched();
}
writecache_commit_flushed(wc, true);
wc->seq_count++;
pmem_assign(sb(wc)->seq_count, cpu_to_le64(wc->seq_count));
writecache_flush_region(wc, &sb(wc)->seq_count, sizeof sb(wc)->seq_count);
writecache_commit_flushed(wc, false);
wc->overwrote_committed = false;
need_flush_after_free = false;
while (1) {
/* Free another committed entry with lower seq-count */
struct rb_node *rb_node = rb_prev(&e->rb_node);
if (rb_node) {
e2 = container_of(rb_node, struct wc_entry, rb_node);
if (read_original_sector(wc, e2) == read_original_sector(wc, e) &&
likely(!e2->write_in_progress)) {
writecache_free_entry(wc, e2);
need_flush_after_free = true;
}
}
if (unlikely(e->lru.prev == &wc->lru))
break;
e = container_of(e->lru.prev, struct wc_entry, lru);
cond_resched();
}
if (need_flush_after_free)
writecache_commit_flushed(wc, false);
}
static void writecache_flush_work(struct work_struct *work)
{
struct dm_writecache *wc = container_of(work, struct dm_writecache, flush_work);
wc_lock(wc);
writecache_flush(wc);
wc_unlock(wc);
}
static void writecache_autocommit_timer(struct timer_list *t)
{
struct dm_writecache *wc = from_timer(wc, t, autocommit_timer);
if (!writecache_has_error(wc))
queue_work(wc->writeback_wq, &wc->flush_work);
}
static void writecache_schedule_autocommit(struct dm_writecache *wc)
{
if (!timer_pending(&wc->autocommit_timer))
mod_timer(&wc->autocommit_timer, jiffies + wc->autocommit_jiffies);
}
static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_t end)
{
struct wc_entry *e;
bool discarded_something = false;
e = writecache_find_entry(wc, start, WFE_RETURN_FOLLOWING | WFE_LOWEST_SEQ);
if (unlikely(!e))
return;
while (read_original_sector(wc, e) < end) {
struct rb_node *node = rb_next(&e->rb_node);
if (likely(!e->write_in_progress)) {
if (!discarded_something) {
writecache_wait_for_ios(wc, READ);
writecache_wait_for_ios(wc, WRITE);
discarded_something = true;
}
writecache_free_entry(wc, e);
}
if (unlikely(!node))
break;
e = container_of(node, struct wc_entry, rb_node);
}
if (discarded_something)
writecache_commit_flushed(wc, false);
}
static bool writecache_wait_for_writeback(struct dm_writecache *wc)
{
if (wc->writeback_size) {
writecache_wait_on_freelist(wc);
return true;
}
return false;
}
static void writecache_suspend(struct dm_target *ti)
{
struct dm_writecache *wc = ti->private;
bool flush_on_suspend;
del_timer_sync(&wc->autocommit_timer);
wc_lock(wc);
writecache_flush(wc);
flush_on_suspend = wc->flush_on_suspend;
if (flush_on_suspend) {
wc->flush_on_suspend = false;
wc->writeback_all++;
queue_work(wc->writeback_wq, &wc->writeback_work);
}
wc_unlock(wc);
drain_workqueue(wc->writeback_wq);
wc_lock(wc);
if (flush_on_suspend)
wc->writeback_all--;
while (writecache_wait_for_writeback(wc));
if (WC_MODE_PMEM(wc))
persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
writecache_poison_lists(wc);
wc_unlock(wc);
}
static int writecache_alloc_entries(struct dm_writecache *wc)
{
size_t b;
if (wc->entries)
return 0;
wc->entries = vmalloc(array_size(sizeof(struct wc_entry), wc->n_blocks));
if (!wc->entries)
return -ENOMEM;
for (b = 0; b < wc->n_blocks; b++) {
struct wc_entry *e = &wc->entries[b];
e->index = b;
e->write_in_progress = false;
}
return 0;
}
static void writecache_resume(struct dm_target *ti)
{
struct dm_writecache *wc = ti->private;
size_t b;
bool need_flush = false;
__le64 sb_seq_count;
int r;
wc_lock(wc);
if (WC_MODE_PMEM(wc))
persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size);
wc->tree = RB_ROOT;
INIT_LIST_HEAD(&wc->lru);
if (WC_MODE_SORT_FREELIST(wc)) {
wc->freetree = RB_ROOT;
wc->current_free = NULL;
} else {
INIT_LIST_HEAD(&wc->freelist);
}
wc->freelist_size = 0;
r = memcpy_mcsafe(&sb_seq_count, &sb(wc)->seq_count, sizeof(uint64_t));
if (r) {
writecache_error(wc, r, "hardware memory error when reading superblock: %d", r);
sb_seq_count = cpu_to_le64(0);
}
wc->seq_count = le64_to_cpu(sb_seq_count);
#ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS
for (b = 0; b < wc->n_blocks; b++) {
struct wc_entry *e = &wc->entries[b];
struct wc_memory_entry wme;
if (writecache_has_error(wc)) {
e->original_sector = -1;
e->seq_count = -1;
continue;
}
r = memcpy_mcsafe(&wme, memory_entry(wc, e), sizeof(struct wc_memory_entry));
if (r) {
writecache_error(wc, r, "hardware memory error when reading metadata entry %lu: %d",
(unsigned long)b, r);
e->original_sector = -1;
e->seq_count = -1;
} else {
e->original_sector = le64_to_cpu(wme.original_sector);
e->seq_count = le64_to_cpu(wme.seq_count);
}
}
#endif
for (b = 0; b < wc->n_blocks; b++) {
struct wc_entry *e = &wc->entries[b];
if (!writecache_entry_is_committed(wc, e)) {
if (read_seq_count(wc, e) != -1) {
erase_this:
clear_seq_count(wc, e);
need_flush = true;
}
writecache_add_to_freelist(wc, e);
} else {
struct wc_entry *old;
old = writecache_find_entry(wc, read_original_sector(wc, e), 0);
if (!old) {
writecache_insert_entry(wc, e);
} else {
if (read_seq_count(wc, old) == read_seq_count(wc, e)) {
writecache_error(wc, -EINVAL,
"two identical entries, position %llu, sector %llu, sequence %llu",
(unsigned long long)b, (unsigned long long)read_original_sector(wc, e),
(unsigned long long)read_seq_count(wc, e));
}
if (read_seq_count(wc, old) > read_seq_count(wc, e)) {
goto erase_this;
} else {
writecache_free_entry(wc, old);
writecache_insert_entry(wc, e);
need_flush = true;
}
}
}
cond_resched();
}
if (need_flush) {
writecache_flush_all_metadata(wc);
writecache_commit_flushed(wc, false);
}
writecache_verify_watermark(wc);
wc_unlock(wc);
}
static int process_flush_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
{
if (argc != 1)
return -EINVAL;
wc_lock(wc);
if (dm_suspended(wc->ti)) {
wc_unlock(wc);
return -EBUSY;
}
if (writecache_has_error(wc)) {
wc_unlock(wc);
return -EIO;
}
writecache_flush(wc);
wc->writeback_all++;
queue_work(wc->writeback_wq, &wc->writeback_work);
wc_unlock(wc);
flush_workqueue(wc->writeback_wq);
wc_lock(wc);
wc->writeback_all--;
if (writecache_has_error(wc)) {
wc_unlock(wc);
return -EIO;
}
wc_unlock(wc);
return 0;
}
static int process_flush_on_suspend_mesg(unsigned argc, char **argv, struct dm_writecache *wc)
{
if (argc != 1)
return -EINVAL;
wc_lock(wc);
wc->flush_on_suspend = true;
wc_unlock(wc);
return 0;
}
static int writecache_message(struct dm_target *ti, unsigned argc, char **argv,
char *result, unsigned maxlen)
{
int r = -EINVAL;
struct dm_writecache *wc = ti->private;
if (!strcasecmp(argv[0], "flush"))
r = process_flush_mesg(argc, argv, wc);
else if (!strcasecmp(argv[0], "flush_on_suspend"))
r = process_flush_on_suspend_mesg(argc, argv, wc);
else
DMERR("unrecognised message received: %s", argv[0]);
return r;
}
static void bio_copy_block(struct dm_writecache *wc, struct bio *bio, void *data)
{
void *buf;
unsigned long flags;
unsigned size;
int rw = bio_data_dir(bio);
unsigned remaining_size = wc->block_size;
do {
struct bio_vec bv = bio_iter_iovec(bio, bio->bi_iter);
buf = bvec_kmap_irq(&bv, &flags);
size = bv.bv_len;
if (unlikely(size > remaining_size))
size = remaining_size;
if (rw == READ) {
int r;
r = memcpy_mcsafe(buf, data, size);
flush_dcache_page(bio_page(bio));
if (unlikely(r)) {
writecache_error(wc, r, "hardware memory error when reading data: %d", r);
bio->bi_status = BLK_STS_IOERR;
}
} else {
flush_dcache_page(bio_page(bio));
memcpy_flushcache(data, buf, size);
}
bvec_kunmap_irq(buf, &flags);
data = (char *)data + size;
remaining_size -= size;
bio_advance(bio, size);
} while (unlikely(remaining_size));
}
static int writecache_flush_thread(void *data)
{
struct dm_writecache *wc = data;
while (1) {
struct bio *bio;
wc_lock(wc);
bio = bio_list_pop(&wc->flush_list);
if (!bio) {
set_current_state(TASK_INTERRUPTIBLE);
wc_unlock(wc);
if (unlikely(kthread_should_stop())) {
set_current_state(TASK_RUNNING);
break;
}
schedule();
continue;
}
if (bio_op(bio) == REQ_OP_DISCARD) {
writecache_discard(wc, bio->bi_iter.bi_sector,
bio_end_sector(bio));
wc_unlock(wc);
bio_set_dev(bio, wc->dev->bdev);
generic_make_request(bio);
} else {
writecache_flush(wc);
wc_unlock(wc);
if (writecache_has_error(wc))
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
}
}
return 0;
}
static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
{
if (bio_list_empty(&wc->flush_list))
wake_up_process(wc->flush_thread);
bio_list_add(&wc->flush_list, bio);
}
static int writecache_map(struct dm_target *ti, struct bio *bio)
{
struct wc_entry *e;
struct dm_writecache *wc = ti->private;
bio->bi_private = NULL;
wc_lock(wc);
if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
if (writecache_has_error(wc))
goto unlock_error;
if (WC_MODE_PMEM(wc)) {
writecache_flush(wc);
if (writecache_has_error(wc))
goto unlock_error;
goto unlock_submit;
} else {
writecache_offload_bio(wc, bio);
goto unlock_return;
}
}
bio->bi_iter.bi_sector = dm_target_offset(ti, bio->bi_iter.bi_sector);
if (unlikely((((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
(wc->block_size / 512 - 1)) != 0)) {
DMERR("I/O is not aligned, sector %llu, size %u, block size %u",
(unsigned long long)bio->bi_iter.bi_sector,
bio->bi_iter.bi_size, wc->block_size);
goto unlock_error;
}
if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {
if (writecache_has_error(wc))
goto unlock_error;
if (WC_MODE_PMEM(wc)) {
writecache_discard(wc, bio->bi_iter.bi_sector, bio_end_sector(bio));
goto unlock_remap_origin;
} else {
writecache_offload_bio(wc, bio);
goto unlock_return;
}
}
if (bio_data_dir(bio) == READ) {
read_next_block:
e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
if (WC_MODE_PMEM(wc)) {
bio_copy_block(wc, bio, memory_data(wc, e));
if (bio->bi_iter.bi_size)
goto read_next_block;
goto unlock_submit;
} else {
dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
bio_set_dev(bio, wc->ssd_dev->bdev);
bio->bi_iter.bi_sector = cache_sector(wc, e);
if (!writecache_entry_is_committed(wc, e))
writecache_wait_for_ios(wc, WRITE);
goto unlock_remap;
}
} else {
if (e) {
sector_t next_boundary =
read_original_sector(wc, e) - bio->bi_iter.bi_sector;
if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
dm_accept_partial_bio(bio, next_boundary);
}
}
goto unlock_remap_origin;
}
} else {
do {
if (writecache_has_error(wc))
goto unlock_error;
e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
if (e) {
if (!writecache_entry_is_committed(wc, e))
goto bio_copy;
if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
wc->overwrote_committed = true;
goto bio_copy;
}
}
e = writecache_pop_from_freelist(wc, (sector_t)-1);
if (unlikely(!e)) {
writecache_wait_on_freelist(wc);
continue;
}
write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
writecache_insert_entry(wc, e);
wc->uncommitted_blocks++;
bio_copy:
if (WC_MODE_PMEM(wc)) {
bio_copy_block(wc, bio, memory_data(wc, e));
} else {
unsigned bio_size = wc->block_size;
sector_t start_cache_sec = cache_sector(wc, e);
sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
while (bio_size < bio->bi_iter.bi_size) {
struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
if (!f)
break;
write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
(bio_size >> SECTOR_SHIFT), wc->seq_count);
writecache_insert_entry(wc, f);
wc->uncommitted_blocks++;
bio_size += wc->block_size;
current_cache_sec += wc->block_size >> SECTOR_SHIFT;
}
bio_set_dev(bio, wc->ssd_dev->bdev);
bio->bi_iter.bi_sector = start_cache_sec;
dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
wc->uncommitted_blocks = 0;
queue_work(wc->writeback_wq, &wc->flush_work);
} else {
writecache_schedule_autocommit(wc);
}
goto unlock_remap;
}
} while (bio->bi_iter.bi_size);
if (unlikely(bio->bi_opf & REQ_FUA ||
wc->uncommitted_blocks >= wc->autocommit_blocks))
writecache_flush(wc);
else
writecache_schedule_autocommit(wc);
goto unlock_submit;
}
unlock_remap_origin:
bio_set_dev(bio, wc->dev->bdev);
wc_unlock(wc);
return DM_MAPIO_REMAPPED;
unlock_remap:
/* make sure that writecache_end_io decrements bio_in_progress: */
bio->bi_private = (void *)1;
atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
wc_unlock(wc);
return DM_MAPIO_REMAPPED;
unlock_submit:
wc_unlock(wc);
bio_endio(bio);
return DM_MAPIO_SUBMITTED;
unlock_return:
wc_unlock(wc);
return DM_MAPIO_SUBMITTED;
unlock_error:
wc_unlock(wc);
bio_io_error(bio);
return DM_MAPIO_SUBMITTED;
}
static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
{
struct dm_writecache *wc = ti->private;
if (bio->bi_private != NULL) {
int dir = bio_data_dir(bio);
if (atomic_dec_and_test(&wc->bio_in_progress[dir]))
if (unlikely(waitqueue_active(&wc->bio_in_progress_wait[dir])))
wake_up(&wc->bio_in_progress_wait[dir]);
}
return 0;
}
static int writecache_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct dm_writecache *wc = ti->private;
return fn(ti, wc->dev, 0, ti->len, data);
}
static void writecache_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
struct dm_writecache *wc = ti->private;
if (limits->logical_block_size < wc->block_size)
limits->logical_block_size = wc->block_size;
if (limits->physical_block_size < wc->block_size)
limits->physical_block_size = wc->block_size;
if (limits->io_min < wc->block_size)
limits->io_min = wc->block_size;
}
static void writecache_writeback_endio(struct bio *bio)
{
struct writeback_struct *wb = container_of(bio, struct writeback_struct, bio);
struct dm_writecache *wc = wb->wc;
unsigned long flags;
raw_spin_lock_irqsave(&wc->endio_list_lock, flags);
if (unlikely(list_empty(&wc->endio_list)))
wake_up_process(wc->endio_thread);
list_add_tail(&wb->endio_entry, &wc->endio_list);
raw_spin_unlock_irqrestore(&wc->endio_list_lock, flags);
}
static void writecache_copy_endio(int read_err, unsigned long write_err, void *ptr)
{
struct copy_struct *c = ptr;
struct dm_writecache *wc = c->wc;
c->error = likely(!(read_err | write_err)) ? 0 : -EIO;
raw_spin_lock_irq(&wc->endio_list_lock);
if (unlikely(list_empty(&wc->endio_list)))
wake_up_process(wc->endio_thread);
list_add_tail(&c->endio_entry, &wc->endio_list);
raw_spin_unlock_irq(&wc->endio_list_lock);
}
static void __writecache_endio_pmem(struct dm_writecache *wc, struct list_head *list)
{
unsigned i;
struct writeback_struct *wb;
struct wc_entry *e;
unsigned long n_walked = 0;
do {
wb = list_entry(list->next, struct writeback_struct, endio_entry);
list_del(&wb->endio_entry);
if (unlikely(wb->bio.bi_status != BLK_STS_OK))
writecache_error(wc, blk_status_to_errno(wb->bio.bi_status),
"write error %d", wb->bio.bi_status);
i = 0;
do {
e = wb->wc_list[i];
BUG_ON(!e->write_in_progress);
e->write_in_progress = false;
INIT_LIST_HEAD(&e->lru);
if (!writecache_has_error(wc))
writecache_free_entry(wc, e);
BUG_ON(!wc->writeback_size);
wc->writeback_size--;
n_walked++;
if (unlikely(n_walked >= ENDIO_LATENCY)) {
writecache_commit_flushed(wc, false);
wc_unlock(wc);
wc_lock(wc);
n_walked = 0;
}
} while (++i < wb->wc_list_n);
if (wb->wc_list != wb->wc_list_inline)
kfree(wb->wc_list);
bio_put(&wb->bio);
} while (!list_empty(list));
}
static void __writecache_endio_ssd(struct dm_writecache *wc, struct list_head *list)
{
struct copy_struct *c;
struct wc_entry *e;
do {
c = list_entry(list->next, struct copy_struct, endio_entry);
list_del(&c->endio_entry);
if (unlikely(c->error))
writecache_error(wc, c->error, "copy error");
e = c->e;
do {
BUG_ON(!e->write_in_progress);
e->write_in_progress = false;
INIT_LIST_HEAD(&e->lru);
if (!writecache_has_error(wc))
writecache_free_entry(wc, e);
BUG_ON(!wc->writeback_size);
wc->writeback_size--;
e++;
} while (--c->n_entries);
mempool_free(c, &wc->copy_pool);
} while (!list_empty(list));
}
static int writecache_endio_thread(void *data)
{
struct dm_writecache *wc = data;
while (1) {
struct list_head list;
raw_spin_lock_irq(&wc->endio_list_lock);
if (!list_empty(&wc->endio_list))
goto pop_from_list;
set_current_state(TASK_INTERRUPTIBLE);
raw_spin_unlock_irq(&wc->endio_list_lock);
if (unlikely(kthread_should_stop())) {
set_current_state(TASK_RUNNING);
break;
}
schedule();
continue;
pop_from_list:
list = wc->endio_list;
list.next->prev = list.prev->next = &list;
INIT_LIST_HEAD(&wc->endio_list);
raw_spin_unlock_irq(&wc->endio_list_lock);
if (!WC_MODE_FUA(wc))
writecache_disk_flush(wc, wc->dev);
wc_lock(wc);
if (WC_MODE_PMEM(wc)) {
__writecache_endio_pmem(wc, &list);
} else {
__writecache_endio_ssd(wc, &list);
writecache_wait_for_ios(wc, READ);
}
writecache_commit_flushed(wc, false);
wc_unlock(wc);
}
return 0;
}
static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e, gfp_t gfp)
{
struct dm_writecache *wc = wb->wc;
unsigned block_size = wc->block_size;
void *address = memory_data(wc, e);
persistent_memory_flush_cache(address, block_size);
return bio_add_page(&wb->bio, persistent_memory_page(address),
block_size, persistent_memory_page_offset(address)) != 0;
}
struct writeback_list {
struct list_head list;
size_t size;
};
static void __writeback_throttle(struct dm_writecache *wc, struct writeback_list *wbl)
{
if (unlikely(wc->max_writeback_jobs)) {
if (READ_ONCE(wc->writeback_size) - wbl->size >= wc->max_writeback_jobs) {
wc_lock(wc);
while (wc->writeback_size - wbl->size >= wc->max_writeback_jobs)
writecache_wait_on_freelist(wc);
wc_unlock(wc);
}
}
cond_resched();
}
static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeback_list *wbl)
{
struct wc_entry *e, *f;
struct bio *bio;
struct writeback_struct *wb;
unsigned max_pages;
while (wbl->size) {
wbl->size--;
e = container_of(wbl->list.prev, struct wc_entry, lru);
list_del(&e->lru);
max_pages = e->wc_list_contiguous;
bio = bio_alloc_bioset(GFP_NOIO, max_pages, &wc->bio_set);
wb = container_of(bio, struct writeback_struct, bio);
wb->wc = wc;
bio->bi_end_io = writecache_writeback_endio;
bio_set_dev(bio, wc->dev->bdev);
bio->bi_iter.bi_sector = read_original_sector(wc, e);
if (max_pages <= WB_LIST_INLINE ||
unlikely(!(wb->wc_list = kmalloc_array(max_pages, sizeof(struct wc_entry *),
GFP_NOIO | __GFP_NORETRY |
__GFP_NOMEMALLOC | __GFP_NOWARN)))) {
wb->wc_list = wb->wc_list_inline;
max_pages = WB_LIST_INLINE;
}
BUG_ON(!wc_add_block(wb, e, GFP_NOIO));
wb->wc_list[0] = e;
wb->wc_list_n = 1;
while (wbl->size && wb->wc_list_n < max_pages) {
f = container_of(wbl->list.prev, struct wc_entry, lru);
if (read_original_sector(wc, f) !=
read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
break;
if (!wc_add_block(wb, f, GFP_NOWAIT | __GFP_NOWARN))
break;
wbl->size--;
list_del(&f->lru);
wb->wc_list[wb->wc_list_n++] = f;
e = f;
}
bio_set_op_attrs(bio, REQ_OP_WRITE, WC_MODE_FUA(wc) * REQ_FUA);
if (writecache_has_error(wc)) {
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
} else {
submit_bio(bio);
}
__writeback_throttle(wc, wbl);
}
}
static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writeback_list *wbl)
{
struct wc_entry *e, *f;
struct dm_io_region from, to;
struct copy_struct *c;
while (wbl->size) {
unsigned n_sectors;
wbl->size--;
e = container_of(wbl->list.prev, struct wc_entry, lru);
list_del(&e->lru);
n_sectors = e->wc_list_contiguous << (wc->block_size_bits - SECTOR_SHIFT);
from.bdev = wc->ssd_dev->bdev;
from.sector = cache_sector(wc, e);
from.count = n_sectors;
to.bdev = wc->dev->bdev;
to.sector = read_original_sector(wc, e);
to.count = n_sectors;
c = mempool_alloc(&wc->copy_pool, GFP_NOIO);
c->wc = wc;
c->e = e;
c->n_entries = e->wc_list_contiguous;
while ((n_sectors -= wc->block_size >> SECTOR_SHIFT)) {
wbl->size--;
f = container_of(wbl->list.prev, struct wc_entry, lru);
BUG_ON(f != e + 1);
list_del(&f->lru);
e = f;
}
dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
__writeback_throttle(wc, wbl);
}
}
static void writecache_writeback(struct work_struct *work)
{
struct dm_writecache *wc = container_of(work, struct dm_writecache, writeback_work);
struct blk_plug plug;
struct wc_entry *f, *uninitialized_var(g), *e = NULL;
struct rb_node *node, *next_node;
struct list_head skipped;
struct writeback_list wbl;
unsigned long n_walked;
wc_lock(wc);
restart:
if (writecache_has_error(wc)) {
wc_unlock(wc);
return;
}
if (unlikely(wc->writeback_all)) {
if (writecache_wait_for_writeback(wc))
goto restart;
}
if (wc->overwrote_committed) {
writecache_wait_for_ios(wc, WRITE);
}
n_walked = 0;
INIT_LIST_HEAD(&skipped);
INIT_LIST_HEAD(&wbl.list);
wbl.size = 0;
while (!list_empty(&wc->lru) &&
(wc->writeback_all ||
wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark)) {
n_walked++;
if (unlikely(n_walked > WRITEBACK_LATENCY) &&
likely(!wc->writeback_all) && likely(!dm_suspended(wc->ti))) {
queue_work(wc->writeback_wq, &wc->writeback_work);
break;
}
if (unlikely(wc->writeback_all)) {
if (unlikely(!e)) {
writecache_flush(wc);
e = container_of(rb_first(&wc->tree), struct wc_entry, rb_node);
} else
e = g;
} else
e = container_of(wc->lru.prev, struct wc_entry, lru);
BUG_ON(e->write_in_progress);
if (unlikely(!writecache_entry_is_committed(wc, e))) {
writecache_flush(wc);
}
node = rb_prev(&e->rb_node);
if (node) {
f = container_of(node, struct wc_entry, rb_node);
if (unlikely(read_original_sector(wc, f) ==
read_original_sector(wc, e))) {
BUG_ON(!f->write_in_progress);
list_del(&e->lru);
list_add(&e->lru, &skipped);
cond_resched();
continue;
}
}
wc->writeback_size++;
list_del(&e->lru);
list_add(&e->lru, &wbl.list);
wbl.size++;
e->write_in_progress = true;
e->wc_list_contiguous = 1;
f = e;
while (1) {
next_node = rb_next(&f->rb_node);
if (unlikely(!next_node))
break;
g = container_of(next_node, struct wc_entry, rb_node);
if (unlikely(read_original_sector(wc, g) ==
read_original_sector(wc, f))) {
f = g;
continue;
}
if (read_original_sector(wc, g) !=
read_original_sector(wc, f) + (wc->block_size >> SECTOR_SHIFT))
break;
if (unlikely(g->write_in_progress))
break;
if (unlikely(!writecache_entry_is_committed(wc, g)))
break;
if (!WC_MODE_PMEM(wc)) {
if (g != f + 1)
break;
}
n_walked++;
//if (unlikely(n_walked > WRITEBACK_LATENCY) && likely(!wc->writeback_all))
// break;
wc->writeback_size++;
list_del(&g->lru);
list_add(&g->lru, &wbl.list);
wbl.size++;
g->write_in_progress = true;
g->wc_list_contiguous = BIO_MAX_PAGES;
f = g;
e->wc_list_contiguous++;
if (unlikely(e->wc_list_contiguous == BIO_MAX_PAGES)) {
if (unlikely(wc->writeback_all)) {
next_node = rb_next(&f->rb_node);
if (likely(next_node))
g = container_of(next_node, struct wc_entry, rb_node);
}
break;
}
}
cond_resched();
}
if (!list_empty(&skipped)) {
list_splice_tail(&skipped, &wc->lru);
/*
* If we didn't do any progress, we must wait until some
* writeback finishes to avoid burning CPU in a loop
*/
if (unlikely(!wbl.size))
writecache_wait_for_writeback(wc);
}
wc_unlock(wc);
blk_start_plug(&plug);
if (WC_MODE_PMEM(wc))
__writecache_writeback_pmem(wc, &wbl);
else
__writecache_writeback_ssd(wc, &wbl);
blk_finish_plug(&plug);
if (unlikely(wc->writeback_all)) {
wc_lock(wc);
while (writecache_wait_for_writeback(wc));
wc_unlock(wc);
}
}
static int calculate_memory_size(uint64_t device_size, unsigned block_size,
size_t *n_blocks_p, size_t *n_metadata_blocks_p)
{
uint64_t n_blocks, offset;
struct wc_entry e;
n_blocks = device_size;
do_div(n_blocks, block_size + sizeof(struct wc_memory_entry));
while (1) {
if (!n_blocks)
return -ENOSPC;
/* Verify the following entries[n_blocks] won't overflow */
if (n_blocks >= ((size_t)-sizeof(struct wc_memory_superblock) /
sizeof(struct wc_memory_entry)))
return -EFBIG;
offset = offsetof(struct wc_memory_superblock, entries[n_blocks]);
offset = (offset + block_size - 1) & ~(uint64_t)(block_size - 1);
if (offset + n_blocks * block_size <= device_size)
break;
n_blocks--;
}
/* check if the bit field overflows */
e.index = n_blocks;
if (e.index != n_blocks)
return -EFBIG;
if (n_blocks_p)
*n_blocks_p = n_blocks;
if (n_metadata_blocks_p)
*n_metadata_blocks_p = offset >> __ffs(block_size);
return 0;
}
static int init_memory(struct dm_writecache *wc)
{
size_t b;
int r;
r = calculate_memory_size(wc->memory_map_size, wc->block_size, &wc->n_blocks, NULL);
if (r)
return r;
r = writecache_alloc_entries(wc);
if (r)
return r;
for (b = 0; b < ARRAY_SIZE(sb(wc)->padding); b++)
pmem_assign(sb(wc)->padding[b], cpu_to_le64(0));
pmem_assign(sb(wc)->version, cpu_to_le32(MEMORY_SUPERBLOCK_VERSION));
pmem_assign(sb(wc)->block_size, cpu_to_le32(wc->block_size));
pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
for (b = 0; b < wc->n_blocks; b++)
write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
writecache_flush_all_metadata(wc);
writecache_commit_flushed(wc, false);
pmem_assign(sb(wc)->magic, cpu_to_le32(MEMORY_SUPERBLOCK_MAGIC));
writecache_flush_region(wc, &sb(wc)->magic, sizeof sb(wc)->magic);
writecache_commit_flushed(wc, false);
return 0;
}
static void writecache_dtr(struct dm_target *ti)
{
struct dm_writecache *wc = ti->private;
if (!wc)
return;
if (wc->endio_thread)
kthread_stop(wc->endio_thread);
if (wc->flush_thread)
kthread_stop(wc->flush_thread);
bioset_exit(&wc->bio_set);
mempool_exit(&wc->copy_pool);
if (wc->writeback_wq)
destroy_workqueue(wc->writeback_wq);
if (wc->dev)
dm_put_device(ti, wc->dev);
if (wc->ssd_dev)
dm_put_device(ti, wc->ssd_dev);
if (wc->entries)
vfree(wc->entries);
if (wc->memory_map) {
if (WC_MODE_PMEM(wc))
persistent_memory_release(wc);
else
vfree(wc->memory_map);
}
if (wc->dm_kcopyd)
dm_kcopyd_client_destroy(wc->dm_kcopyd);
if (wc->dm_io)
dm_io_client_destroy(wc->dm_io);
if (wc->dirty_bitmap)
vfree(wc->dirty_bitmap);
kfree(wc);
}
static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
struct dm_writecache *wc;
struct dm_arg_set as;
const char *string;
unsigned opt_params;
size_t offset, data_size;
int i, r;
char dummy;
int high_wm_percent = HIGH_WATERMARK;
int low_wm_percent = LOW_WATERMARK;
uint64_t x;
struct wc_memory_superblock s;
static struct dm_arg _args[] = {
{0, 10, "Invalid number of feature args"},
};
as.argc = argc;
as.argv = argv;
wc = kzalloc(sizeof(struct dm_writecache), GFP_KERNEL);
if (!wc) {
ti->error = "Cannot allocate writecache structure";
r = -ENOMEM;
goto bad;
}
ti->private = wc;
wc->ti = ti;
mutex_init(&wc->lock);
writecache_poison_lists(wc);
init_waitqueue_head(&wc->freelist_wait);
timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0);
for (i = 0; i < 2; i++) {
atomic_set(&wc->bio_in_progress[i], 0);
init_waitqueue_head(&wc->bio_in_progress_wait[i]);
}
wc->dm_io = dm_io_client_create();
if (IS_ERR(wc->dm_io)) {
r = PTR_ERR(wc->dm_io);
ti->error = "Unable to allocate dm-io client";
wc->dm_io = NULL;
goto bad;
}
wc->writeback_wq = alloc_workqueue("writecache-writeback", WQ_MEM_RECLAIM, 1);
if (!wc->writeback_wq) {
r = -ENOMEM;
ti->error = "Could not allocate writeback workqueue";
goto bad;
}
INIT_WORK(&wc->writeback_work, writecache_writeback);
INIT_WORK(&wc->flush_work, writecache_flush_work);
raw_spin_lock_init(&wc->endio_list_lock);
INIT_LIST_HEAD(&wc->endio_list);
wc->endio_thread = kthread_create(writecache_endio_thread, wc, "writecache_endio");
if (IS_ERR(wc->endio_thread)) {
r = PTR_ERR(wc->endio_thread);
wc->endio_thread = NULL;
ti->error = "Couldn't spawn endio thread";
goto bad;
}
wake_up_process(wc->endio_thread);
/*
* Parse the mode (pmem or ssd)
*/
string = dm_shift_arg(&as);
if (!string)
goto bad_arguments;
if (!strcasecmp(string, "s")) {
wc->pmem_mode = false;
} else if (!strcasecmp(string, "p")) {
#ifdef DM_WRITECACHE_HAS_PMEM
wc->pmem_mode = true;
wc->writeback_fua = true;
#else
/*
* If the architecture doesn't support persistent memory or
* the kernel doesn't support any DAX drivers, this driver can
* only be used in SSD-only mode.
*/
r = -EOPNOTSUPP;
ti->error = "Persistent memory or DAX not supported on this system";
goto bad;
#endif
} else {
goto bad_arguments;
}
if (WC_MODE_PMEM(wc)) {
r = bioset_init(&wc->bio_set, BIO_POOL_SIZE,
offsetof(struct writeback_struct, bio),
BIOSET_NEED_BVECS);
if (r) {
ti->error = "Could not allocate bio set";
goto bad;
}
} else {
r = mempool_init_kmalloc_pool(&wc->copy_pool, 1, sizeof(struct copy_struct));
if (r) {
ti->error = "Could not allocate mempool";
goto bad;
}
}
/*
* Parse the origin data device
*/
string = dm_shift_arg(&as);
if (!string)
goto bad_arguments;
r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->dev);
if (r) {
ti->error = "Origin data device lookup failed";
goto bad;
}
/*
* Parse cache data device (be it pmem or ssd)
*/
string = dm_shift_arg(&as);
if (!string)
goto bad_arguments;
r = dm_get_device(ti, string, dm_table_get_mode(ti->table), &wc->ssd_dev);
if (r) {
ti->error = "Cache data device lookup failed";
goto bad;
}
wc->memory_map_size = i_size_read(wc->ssd_dev->bdev->bd_inode);
/*
* Parse the cache block size
*/
string = dm_shift_arg(&as);
if (!string)
goto bad_arguments;
if (sscanf(string, "%u%c", &wc->block_size, &dummy) != 1 ||
wc->block_size < 512 || wc->block_size > PAGE_SIZE ||
(wc->block_size & (wc->block_size - 1))) {
r = -EINVAL;
ti->error = "Invalid block size";
goto bad;
}
wc->block_size_bits = __ffs(wc->block_size);
wc->max_writeback_jobs = MAX_WRITEBACK_JOBS;
wc->autocommit_blocks = !WC_MODE_PMEM(wc) ? AUTOCOMMIT_BLOCKS_SSD : AUTOCOMMIT_BLOCKS_PMEM;
wc->autocommit_jiffies = msecs_to_jiffies(AUTOCOMMIT_MSEC);
/*
* Parse optional arguments
*/
r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
if (r)
goto bad;
while (opt_params) {
string = dm_shift_arg(&as), opt_params--;
if (!strcasecmp(string, "start_sector") && opt_params >= 1) {
unsigned long long start_sector;
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
goto invalid_optional;
wc->start_sector = start_sector;
if (wc->start_sector != start_sector ||
wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
goto invalid_optional;
} else if (!strcasecmp(string, "high_watermark") && opt_params >= 1) {
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%d%c", &high_wm_percent, &dummy) != 1)
goto invalid_optional;
if (high_wm_percent < 0 || high_wm_percent > 100)
goto invalid_optional;
wc->high_wm_percent_set = true;
} else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
goto invalid_optional;
if (low_wm_percent < 0 || low_wm_percent > 100)
goto invalid_optional;
wc->low_wm_percent_set = true;
} else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%u%c", &wc->max_writeback_jobs, &dummy) != 1)
goto invalid_optional;
wc->max_writeback_jobs_set = true;
} else if (!strcasecmp(string, "autocommit_blocks") && opt_params >= 1) {
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%u%c", &wc->autocommit_blocks, &dummy) != 1)
goto invalid_optional;
wc->autocommit_blocks_set = true;
} else if (!strcasecmp(string, "autocommit_time") && opt_params >= 1) {
unsigned autocommit_msecs;
string = dm_shift_arg(&as), opt_params--;
if (sscanf(string, "%u%c", &autocommit_msecs, &dummy) != 1)
goto invalid_optional;
if (autocommit_msecs > 3600000)
goto invalid_optional;
wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
wc->autocommit_time_set = true;
} else if (!strcasecmp(string, "fua")) {
if (WC_MODE_PMEM(wc)) {
wc->writeback_fua = true;
wc->writeback_fua_set = true;
} else goto invalid_optional;
} else if (!strcasecmp(string, "nofua")) {
if (WC_MODE_PMEM(wc)) {
wc->writeback_fua = false;
wc->writeback_fua_set = true;
} else goto invalid_optional;
} else {
invalid_optional:
r = -EINVAL;
ti->error = "Invalid optional argument";
goto bad;
}
}
if (high_wm_percent < low_wm_percent) {
r = -EINVAL;
ti->error = "High watermark must be greater than or equal to low watermark";
goto bad;
}
if (WC_MODE_PMEM(wc)) {
r = persistent_memory_claim(wc);
if (r) {
ti->error = "Unable to map persistent memory for cache";
goto bad;
}
} else {
struct dm_io_region region;
struct dm_io_request req;
size_t n_blocks, n_metadata_blocks;
uint64_t n_bitmap_bits;
wc->memory_map_size -= (uint64_t)wc->start_sector << SECTOR_SHIFT;
bio_list_init(&wc->flush_list);
wc->flush_thread = kthread_create(writecache_flush_thread, wc, "dm_writecache_flush");
if (IS_ERR(wc->flush_thread)) {
r = PTR_ERR(wc->flush_thread);
wc->flush_thread = NULL;
ti->error = "Couldn't spawn flush thread";
goto bad;
}
wake_up_process(wc->flush_thread);
r = calculate_memory_size(wc->memory_map_size, wc->block_size,
&n_blocks, &n_metadata_blocks);
if (r) {
ti->error = "Invalid device size";
goto bad;
}
n_bitmap_bits = (((uint64_t)n_metadata_blocks << wc->block_size_bits) +
BITMAP_GRANULARITY - 1) / BITMAP_GRANULARITY;
/* this is limitation of test_bit functions */
if (n_bitmap_bits > 1U << 31) {
r = -EFBIG;
ti->error = "Invalid device size";
goto bad;
}
wc->memory_map = vmalloc(n_metadata_blocks << wc->block_size_bits);
if (!wc->memory_map) {
r = -ENOMEM;
ti->error = "Unable to allocate memory for metadata";
goto bad;
}
wc->dm_kcopyd = dm_kcopyd_client_create(&dm_kcopyd_throttle);
if (IS_ERR(wc->dm_kcopyd)) {
r = PTR_ERR(wc->dm_kcopyd);
ti->error = "Unable to allocate dm-kcopyd client";
wc->dm_kcopyd = NULL;
goto bad;
}
wc->metadata_sectors = n_metadata_blocks << (wc->block_size_bits - SECTOR_SHIFT);
wc->dirty_bitmap_size = (n_bitmap_bits + BITS_PER_LONG - 1) /
BITS_PER_LONG * sizeof(unsigned long);
wc->dirty_bitmap = vzalloc(wc->dirty_bitmap_size);
if (!wc->dirty_bitmap) {
r = -ENOMEM;
ti->error = "Unable to allocate dirty bitmap";
goto bad;
}
region.bdev = wc->ssd_dev->bdev;
region.sector = wc->start_sector;
region.count = wc->metadata_sectors;
req.bi_op = REQ_OP_READ;
req.bi_op_flags = REQ_SYNC;
req.mem.type = DM_IO_VMA;
req.mem.ptr.vma = (char *)wc->memory_map;
req.client = wc->dm_io;
req.notify.fn = NULL;
r = dm_io(&req, 1, &region, NULL);
if (r) {
ti->error = "Unable to read metadata";
goto bad;
}
}
r = memcpy_mcsafe(&s, sb(wc), sizeof(struct wc_memory_superblock));
if (r) {
ti->error = "Hardware memory error when reading superblock";
goto bad;
}
if (!le32_to_cpu(s.magic) && !le32_to_cpu(s.version)) {
r = init_memory(wc);
if (r) {
ti->error = "Unable to initialize device";
goto bad;
}
r = memcpy_mcsafe(&s, sb(wc), sizeof(struct wc_memory_superblock));
if (r) {
ti->error = "Hardware memory error when reading superblock";
goto bad;
}
}
if (le32_to_cpu(s.magic) != MEMORY_SUPERBLOCK_MAGIC) {
ti->error = "Invalid magic in the superblock";
r = -EINVAL;
goto bad;
}
if (le32_to_cpu(s.version) != MEMORY_SUPERBLOCK_VERSION) {
ti->error = "Invalid version in the superblock";
r = -EINVAL;
goto bad;
}
if (le32_to_cpu(s.block_size) != wc->block_size) {
ti->error = "Block size does not match superblock";
r = -EINVAL;
goto bad;
}
wc->n_blocks = le64_to_cpu(s.n_blocks);
offset = wc->n_blocks * sizeof(struct wc_memory_entry);
if (offset / sizeof(struct wc_memory_entry) != le64_to_cpu(sb(wc)->n_blocks)) {
overflow:
ti->error = "Overflow in size calculation";
r = -EINVAL;
goto bad;
}
offset += sizeof(struct wc_memory_superblock);
if (offset < sizeof(struct wc_memory_superblock))
goto overflow;
offset = (offset + wc->block_size - 1) & ~(size_t)(wc->block_size - 1);
data_size = wc->n_blocks * (size_t)wc->block_size;
if (!offset || (data_size / wc->block_size != wc->n_blocks) ||
(offset + data_size < offset))
goto overflow;
if (offset + data_size > wc->memory_map_size) {
ti->error = "Memory area is too small";
r = -EINVAL;
goto bad;
}
wc->metadata_sectors = offset >> SECTOR_SHIFT;
wc->block_start = (char *)sb(wc) + offset;
x = (uint64_t)wc->n_blocks * (100 - high_wm_percent);
x += 50;
do_div(x, 100);
wc->freelist_high_watermark = x;
x = (uint64_t)wc->n_blocks * (100 - low_wm_percent);
x += 50;
do_div(x, 100);
wc->freelist_low_watermark = x;
r = writecache_alloc_entries(wc);
if (r) {
ti->error = "Cannot allocate memory";
goto bad;
}
ti->num_flush_bios = 1;
ti->flush_supported = true;
ti->num_discard_bios = 1;
if (WC_MODE_PMEM(wc))
persistent_memory_flush_cache(wc->memory_map, wc->memory_map_size);
return 0;
bad_arguments:
r = -EINVAL;
ti->error = "Bad arguments";
bad:
writecache_dtr(ti);
return r;
}
static void writecache_status(struct dm_target *ti, status_type_t type,
unsigned status_flags, char *result, unsigned maxlen)
{
struct dm_writecache *wc = ti->private;
unsigned extra_args;
unsigned sz = 0;
uint64_t x;
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%ld %llu %llu %llu", writecache_has_error(wc),
(unsigned long long)wc->n_blocks, (unsigned long long)wc->freelist_size,
(unsigned long long)wc->writeback_size);
break;
case STATUSTYPE_TABLE:
DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
wc->dev->name, wc->ssd_dev->name, wc->block_size);
extra_args = 0;
if (wc->start_sector)
extra_args += 2;
if (wc->high_wm_percent_set)
extra_args += 2;
if (wc->low_wm_percent_set)
extra_args += 2;
if (wc->max_writeback_jobs_set)
extra_args += 2;
if (wc->autocommit_blocks_set)
extra_args += 2;
if (wc->autocommit_time_set)
extra_args += 2;
if (wc->writeback_fua_set)
extra_args++;
DMEMIT("%u", extra_args);
if (wc->start_sector)
DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
if (wc->high_wm_percent_set) {
x = (uint64_t)wc->freelist_high_watermark * 100;
x += wc->n_blocks / 2;
do_div(x, (size_t)wc->n_blocks);
DMEMIT(" high_watermark %u", 100 - (unsigned)x);
}
if (wc->low_wm_percent_set) {
x = (uint64_t)wc->freelist_low_watermark * 100;
x += wc->n_blocks / 2;
do_div(x, (size_t)wc->n_blocks);
DMEMIT(" low_watermark %u", 100 - (unsigned)x);
}
if (wc->max_writeback_jobs_set)
DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
if (wc->autocommit_blocks_set)
DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
if (wc->autocommit_time_set)
DMEMIT(" autocommit_time %u", jiffies_to_msecs(wc->autocommit_jiffies));
if (wc->writeback_fua_set)
DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
break;
}
}
static struct target_type writecache_target = {
.name = "writecache",
.version = {1, 2, 0},
.module = THIS_MODULE,
.ctr = writecache_ctr,
.dtr = writecache_dtr,
.status = writecache_status,
.postsuspend = writecache_suspend,
.resume = writecache_resume,
.message = writecache_message,
.map = writecache_map,
.end_io = writecache_end_io,
.iterate_devices = writecache_iterate_devices,
.io_hints = writecache_io_hints,
};
static int __init dm_writecache_init(void)
{
int r;
r = dm_register_target(&writecache_target);
if (r < 0) {
DMERR("register failed %d", r);
return r;
}
return 0;
}
static void __exit dm_writecache_exit(void)
{
dm_unregister_target(&writecache_target);
}
module_init(dm_writecache_init);
module_exit(dm_writecache_exit);
MODULE_DESCRIPTION(DM_NAME " writecache target");
MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");