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writeback: move backing_dev_info->bdi_stat[] into bdi_writeback

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Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear.  For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi.  To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.

This patch moves bdi->bdi_stat[] into wb.

* enum bdi_stat_item is renamed to wb_stat_item and the prefix of all
  enums is changed from BDI_ to WB_.

* BDI_STAT_BATCH() -> WB_STAT_BATCH()

* [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...)

* bdi_stat[_error]() -> wb_stat[_error]()

* bdi_writeout_inc() -> wb_writeout_inc()

* stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and
  frees stat.

* As there's still only one bdi_writeback per backing_dev_info, all
  uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
  introducing no behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-05-22 17:13:27 -04:00 committed by Jens Axboe
parent 4452226ea2
commit 93f78d8828
7 changed files with 106 additions and 96 deletions
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2
fs/fs-writeback.c
View file

@ -840,7 +840,7 @@ static bool over_bground_thresh(struct backing_dev_info *bdi)
global_page_state(NR_UNSTABLE_NFS) > background_thresh)
return true;
if (bdi_stat(bdi, BDI_RECLAIMABLE) >
if (wb_stat(&bdi->wb, WB_RECLAIMABLE) >
bdi_dirty_limit(bdi, background_thresh))
return true;

12
fs/fuse/file.c
View file

@ -1445,9 +1445,9 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
list_del(&req->writepages_entry);
for (i = 0; i < req->num_pages; i++) {
dec_bdi_stat(bdi, BDI_WRITEBACK);
dec_wb_stat(&bdi->wb, WB_WRITEBACK);
dec_zone_page_state(req->pages[i], NR_WRITEBACK_TEMP);
bdi_writeout_inc(bdi);
wb_writeout_inc(&bdi->wb);
}
wake_up(&fi->page_waitq);
}
@ -1634,7 +1634,7 @@ static int fuse_writepage_locked(struct page *page)
req->end = fuse_writepage_end;
req->inode = inode;
inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
spin_lock(&fc->lock);
@ -1749,9 +1749,9 @@ static bool fuse_writepage_in_flight(struct fuse_req *new_req,
copy_highpage(old_req->pages[0], page);
spin_unlock(&fc->lock);
dec_bdi_stat(bdi, BDI_WRITEBACK);
dec_wb_stat(&bdi->wb, WB_WRITEBACK);
dec_zone_page_state(page, NR_WRITEBACK_TEMP);
bdi_writeout_inc(bdi);
wb_writeout_inc(&bdi->wb);
fuse_writepage_free(fc, new_req);
fuse_request_free(new_req);
goto out;
@ -1848,7 +1848,7 @@ static int fuse_writepages_fill(struct page *page,
req->page_descs[req->num_pages].offset = 0;
req->page_descs[req->num_pages].length = PAGE_SIZE;
inc_bdi_stat(inode_to_bdi(inode), BDI_WRITEBACK);
inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
err = 0;

2
fs/nfs/internal.h
View file

@ -607,7 +607,7 @@ void nfs_mark_page_unstable(struct page *page)
struct inode *inode = page_file_mapping(page)->host;
inc_zone_page_state(page, NR_UNSTABLE_NFS);
inc_bdi_stat(inode_to_bdi(inode), BDI_RECLAIMABLE);
inc_wb_stat(&inode_to_bdi(inode)->wb, WB_RECLAIMABLE);
__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
}

3
fs/nfs/write.c
View file

@ -853,7 +853,8 @@ static void
nfs_clear_page_commit(struct page *page)
{
dec_zone_page_state(page, NR_UNSTABLE_NFS);
dec_bdi_stat(inode_to_bdi(page_file_mapping(page)->host), BDI_RECLAIMABLE);
dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
WB_RECLAIMABLE);
}
/* Called holding inode (/cinfo) lock */

68
include/linux/backing-dev.h
View file

@ -36,15 +36,15 @@ enum wb_state {
typedef int (congested_fn)(void *, int);
enum bdi_stat_item {
BDI_RECLAIMABLE,
BDI_WRITEBACK,
BDI_DIRTIED,
BDI_WRITTEN,
NR_BDI_STAT_ITEMS
enum wb_stat_item {
WB_RECLAIMABLE,
WB_WRITEBACK,
WB_DIRTIED,
WB_WRITTEN,
NR_WB_STAT_ITEMS
};
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
struct bdi_writeback {
struct backing_dev_info *bdi; /* our parent bdi */
@ -58,6 +58,8 @@ struct bdi_writeback {
struct list_head b_more_io; /* parked for more writeback */
struct list_head b_dirty_time; /* time stamps are dirty */
spinlock_t list_lock; /* protects the b_* lists */
struct percpu_counter stat[NR_WB_STAT_ITEMS];
};
struct backing_dev_info {
@ -69,8 +71,6 @@ struct backing_dev_info {
char *name;
struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
unsigned long bw_time_stamp; /* last time write bw is updated */
unsigned long dirtied_stamp;
unsigned long written_stamp; /* pages written at bw_time_stamp */
@ -137,78 +137,74 @@ static inline int wb_has_dirty_io(struct bdi_writeback *wb)
!list_empty(&wb->b_more_io);
}
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
static inline void __add_wb_stat(struct bdi_writeback *wb,
enum wb_stat_item item, s64 amount)
{
__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
__percpu_counter_add(&wb->stat[item], amount, WB_STAT_BATCH);
}
static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline void __inc_wb_stat(struct bdi_writeback *wb,
enum wb_stat_item item)
{
__add_bdi_stat(bdi, item, 1);
__add_wb_stat(wb, item, 1);
}
static inline void inc_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
unsigned long flags;
local_irq_save(flags);
__inc_bdi_stat(bdi, item);
__inc_wb_stat(wb, item);
local_irq_restore(flags);
}
static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline void __dec_wb_stat(struct bdi_writeback *wb,
enum wb_stat_item item)
{
__add_bdi_stat(bdi, item, -1);
__add_wb_stat(wb, item, -1);
}
static inline void dec_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
unsigned long flags;
local_irq_save(flags);
__dec_bdi_stat(bdi, item);
__dec_wb_stat(wb, item);
local_irq_restore(flags);
}
static inline s64 bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
{
return percpu_counter_read_positive(&bdi->bdi_stat[item]);
return percpu_counter_read_positive(&wb->stat[item]);
}
static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
enum wb_stat_item item)
{
return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
return percpu_counter_sum_positive(&wb->stat[item]);
}
static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
enum bdi_stat_item item)
static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
{
s64 sum;
unsigned long flags;
local_irq_save(flags);
sum = __bdi_stat_sum(bdi, item);
sum = __wb_stat_sum(wb, item);
local_irq_restore(flags);
return sum;
}
extern void bdi_writeout_inc(struct backing_dev_info *bdi);
extern void wb_writeout_inc(struct bdi_writeback *wb);
/*
* maximal error of a stat counter.
*/
static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
{
#ifdef CONFIG_SMP
return nr_cpu_ids * BDI_STAT_BATCH;
return nr_cpu_ids * WB_STAT_BATCH;
#else
return 1;
#endif

60
mm/backing-dev.c
View file

@ -84,13 +84,13 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
"b_dirty_time: %10lu\n"
"bdi_list: %10u\n"
"state: %10lx\n",
(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
(unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
(unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
K(bdi_thresh),
K(dirty_thresh),
K(background_thresh),
(unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
(unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
(unsigned long) K(wb_stat(wb, WB_DIRTIED)),
(unsigned long) K(wb_stat(wb, WB_WRITTEN)),
(unsigned long) K(bdi->write_bandwidth),
nr_dirty,
nr_io,
@ -376,8 +376,10 @@ void bdi_unregister(struct backing_dev_info *bdi)
}
EXPORT_SYMBOL(bdi_unregister);
static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
{
int i, err;
memset(wb, 0, sizeof(*wb));
wb->bdi = bdi;
@ -388,6 +390,27 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
INIT_LIST_HEAD(&wb->b_dirty_time);
spin_lock_init(&wb->list_lock);
INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
err = percpu_counter_init(&wb->stat[i], 0, GFP_KERNEL);
if (err) {
while (--i)
percpu_counter_destroy(&wb->stat[i]);
return err;
}
}
return 0;
}
static void bdi_wb_exit(struct bdi_writeback *wb)
{
int i;
WARN_ON(delayed_work_pending(&wb->dwork));
for (i = 0; i < NR_WB_STAT_ITEMS; i++)
percpu_counter_destroy(&wb->stat[i]);
}
/*
@ -397,7 +420,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
int bdi_init(struct backing_dev_info *bdi)
{
int i, err;
int err;
bdi->dev = NULL;
@ -408,13 +431,9 @@ int bdi_init(struct backing_dev_info *bdi)
INIT_LIST_HEAD(&bdi->bdi_list);
INIT_LIST_HEAD(&bdi->work_list);
bdi_wb_init(&bdi->wb, bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0, GFP_KERNEL);
if (err)
goto err;
}
err = bdi_wb_init(&bdi->wb, bdi);
if (err)
return err;
bdi->dirty_exceeded = 0;
@ -427,25 +446,20 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->avg_write_bandwidth = INIT_BW;
err = fprop_local_init_percpu(&bdi->completions, GFP_KERNEL);
if (err) {
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
bdi_wb_exit(&bdi->wb);
return err;
}
return err;
return 0;
}
EXPORT_SYMBOL(bdi_init);
void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
bdi_wb_shutdown(bdi);
WARN_ON(!list_empty(&bdi->work_list));
WARN_ON(delayed_work_pending(&bdi->wb.dwork));
if (bdi->dev) {
bdi_debug_unregister(bdi);
@ -453,8 +467,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
bdi->dev = NULL;
}
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
bdi_wb_exit(&bdi->wb);
fprop_local_destroy_percpu(&bdi->completions);
}
EXPORT_SYMBOL(bdi_destroy);

55
mm/page-writeback.c
View file

@ -396,11 +396,11 @@ static unsigned long wp_next_time(unsigned long cur_time)
* Increment the BDI's writeout completion count and the global writeout
* completion count. Called from test_clear_page_writeback().
*/
static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
static inline void __wb_writeout_inc(struct bdi_writeback *wb)
{
__inc_bdi_stat(bdi, BDI_WRITTEN);
__fprop_inc_percpu_max(&writeout_completions, &bdi->completions,
bdi->max_prop_frac);
__inc_wb_stat(wb, WB_WRITTEN);
__fprop_inc_percpu_max(&writeout_completions, &wb->bdi->completions,
wb->bdi->max_prop_frac);
/* First event after period switching was turned off? */
if (!unlikely(writeout_period_time)) {
/*
@ -414,15 +414,15 @@ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
}
}
void bdi_writeout_inc(struct backing_dev_info *bdi)
void wb_writeout_inc(struct bdi_writeback *wb)
{
unsigned long flags;
local_irq_save(flags);
__bdi_writeout_inc(bdi);
__wb_writeout_inc(wb);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(bdi_writeout_inc);
EXPORT_SYMBOL_GPL(wb_writeout_inc);
/*
* Obtain an accurate fraction of the BDI's portion.
@ -1130,8 +1130,8 @@ void __bdi_update_bandwidth(struct backing_dev_info *bdi,
if (elapsed < BANDWIDTH_INTERVAL)
return;
dirtied = percpu_counter_read(&bdi->bdi_stat[BDI_DIRTIED]);
written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]);
dirtied = percpu_counter_read(&bdi->wb.stat[WB_DIRTIED]);
written = percpu_counter_read(&bdi->wb.stat[WB_WRITTEN]);
/*
* Skip quiet periods when disk bandwidth is under-utilized.
@ -1288,7 +1288,8 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
unsigned long *bdi_thresh,
unsigned long *bdi_bg_thresh)
{
unsigned long bdi_reclaimable;
struct bdi_writeback *wb = &bdi->wb;
unsigned long wb_reclaimable;
/*
* bdi_thresh is not treated as some limiting factor as
@ -1320,14 +1321,12 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
* actually dirty; with m+n sitting in the percpu
* deltas.
*/
if (*bdi_thresh < 2 * bdi_stat_error(bdi)) {
bdi_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
*bdi_dirty = bdi_reclaimable +
bdi_stat_sum(bdi, BDI_WRITEBACK);
if (*bdi_thresh < 2 * wb_stat_error(wb)) {
wb_reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE);
*bdi_dirty = wb_reclaimable + wb_stat_sum(wb, WB_WRITEBACK);
} else {
bdi_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
*bdi_dirty = bdi_reclaimable +
bdi_stat(bdi, BDI_WRITEBACK);
wb_reclaimable = wb_stat(wb, WB_RECLAIMABLE);
*bdi_dirty = wb_reclaimable + wb_stat(wb, WB_WRITEBACK);
}
}
@ -1514,9 +1513,9 @@ pause:
* In theory 1 page is enough to keep the comsumer-producer
* pipe going: the flusher cleans 1 page => the task dirties 1
* more page. However bdi_dirty has accounting errors. So use
* the larger and more IO friendly bdi_stat_error.
* the larger and more IO friendly wb_stat_error.
*/
if (bdi_dirty <= bdi_stat_error(bdi))
if (bdi_dirty <= wb_stat_error(&bdi->wb))
break;
if (fatal_signal_pending(current))
@ -2106,8 +2105,8 @@ void account_page_dirtied(struct page *page, struct address_space *mapping,
mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
__inc_zone_page_state(page, NR_FILE_DIRTY);
__inc_zone_page_state(page, NR_DIRTIED);
__inc_bdi_stat(bdi, BDI_RECLAIMABLE);
__inc_bdi_stat(bdi, BDI_DIRTIED);
__inc_wb_stat(&bdi->wb, WB_RECLAIMABLE);
__inc_wb_stat(&bdi->wb, WB_DIRTIED);
task_io_account_write(PAGE_CACHE_SIZE);
current->nr_dirtied++;
this_cpu_inc(bdp_ratelimits);
@ -2126,7 +2125,7 @@ void account_page_cleaned(struct page *page, struct address_space *mapping,
if (mapping_cap_account_dirty(mapping)) {
mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
dec_zone_page_state(page, NR_FILE_DIRTY);
dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_RECLAIMABLE);
task_io_account_cancelled_write(PAGE_CACHE_SIZE);
}
}
@ -2190,7 +2189,7 @@ void account_page_redirty(struct page *page)
if (mapping && mapping_cap_account_dirty(mapping)) {
current->nr_dirtied--;
dec_zone_page_state(page, NR_DIRTIED);
dec_bdi_stat(inode_to_bdi(mapping->host), BDI_DIRTIED);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_DIRTIED);
}
}
EXPORT_SYMBOL(account_page_redirty);
@ -2369,8 +2368,8 @@ int clear_page_dirty_for_io(struct page *page)
if (TestClearPageDirty(page)) {
mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
dec_zone_page_state(page, NR_FILE_DIRTY);
dec_bdi_stat(inode_to_bdi(mapping->host),
BDI_RECLAIMABLE);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb,
WB_RECLAIMABLE);
ret = 1;
}
mem_cgroup_end_page_stat(memcg);
@ -2398,8 +2397,8 @@ int test_clear_page_writeback(struct page *page)
page_index(page),
PAGECACHE_TAG_WRITEBACK);
if (bdi_cap_account_writeback(bdi)) {
__dec_bdi_stat(bdi, BDI_WRITEBACK);
__bdi_writeout_inc(bdi);
__dec_wb_stat(&bdi->wb, WB_WRITEBACK);
__wb_writeout_inc(&bdi->wb);
}
}
spin_unlock_irqrestore(&mapping->tree_lock, flags);
@ -2433,7 +2432,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
page_index(page),
PAGECACHE_TAG_WRITEBACK);
if (bdi_cap_account_writeback(bdi))
__inc_bdi_stat(bdi, BDI_WRITEBACK);
__inc_wb_stat(&bdi->wb, WB_WRITEBACK);
}
if (!PageDirty(page))
radix_tree_tag_clear(&mapping->page_tree,