[PATCH 13/49] writeback: move bandwidth related fields from backing_dev_info into bdi_writeback

Tejun Heo
2015-04-06T20:24:18Z

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 bandwidth related fields from backing_dev_info into
bdi_writeback.

* The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp,
write_bandwidth, avg_write_bandwidth, dirty_ratelimit,
balanced_dirty_ratelimit, completions and dirty_exceeded.

* writeback_chunk_size() and over_bgroup_thresh() now take @wb instead
of @bdi.

* bdi_writeout_fraction(bdi, ...) -> wb_writeout_fraction(wb, ...)
bdi_dirty_limit(bdi, ...) -> wb_dirty_limit(wb, ...)
bdi_position_ration(bdi, ...) -> wb_position_ratio(wb, ...)
bdi_update_writebandwidth(bdi, ...) -> wb_update_write_bandwidth(wb, ...)
[__]bdi_update_bandwidth(bdi, ...) -> [__]wb_update_bandwidth(wb, ...)
bdi_{max|min}_pause(bdi, ...) -> wb_{max|min}_pause(wb, ...)
bdi_dirty_limits(bdi, ...) -> wb_dirty_limits(wb, ...)

* Init/exits of the relocated fields are moved to bdi_wb_init/exit()
respectively. Note that explicit zeroing is dropped in the process
as wb's are cleared in entirety anyway.

* 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>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
---
fs/f2fs/node.c | 4 +-
fs/f2fs/segment.h | 2 +-
fs/fs-writeback.c | 17 ++-
fs/gfs2/super.c | 2 +-
include/linux/backing-dev.h | 20 +--
include/linux/writeback.h | 19 ++-
include/trace/events/writeback.h | 8 +-
mm/backing-dev.c | 45 +++----
mm/page-writeback.c | 262 ++++++++++++++++++++-------------------
9 files changed, 187 insertions(+), 192 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 97bd9d3..a97da4e 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -51,7 +51,7 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
PAGE_CACHE_SHIFT;
res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 2);
} else if (type == DIRTY_DENTS) {
- if (sbi->sb->s_bdi->dirty_exceeded)
+ if (sbi->sb->s_bdi->wb.dirty_exceeded)
return false;
mem_size = get_pages(sbi, F2FS_DIRTY_DENTS);
res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
@@ -63,7 +63,7 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
sizeof(struct ino_entry)) >> PAGE_CACHE_SHIFT;
res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
} else {
- if (sbi->sb->s_bdi->dirty_exceeded)
+ if (sbi->sb->s_bdi->wb.dirty_exceeded)
return false;
}
return res;
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 7fd3511..3a5bfcf 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -712,7 +712,7 @@ static inline unsigned int max_hw_blocks(struct f2fs_sb_info *sbi)
*/
static inline int nr_pages_to_skip(struct f2fs_sb_info *sbi, int type)
{
- if (sbi->sb->s_bdi->dirty_exceeded)
+ if (sbi->sb->s_bdi->wb.dirty_exceeded)
return 0;

if (type == DATA)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 992a065..4fcf2385 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -606,7 +606,7 @@ out:
return ret;
}

-static long writeback_chunk_size(struct backing_dev_info *bdi,
+static long writeback_chunk_size(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
long pages;
@@ -627,7 +627,7 @@ static long writeback_chunk_size(struct backing_dev_info *bdi,
if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)
pages = LONG_MAX;
else {
- pages = min(bdi->avg_write_bandwidth / 2,
+ pages = min(wb->avg_write_bandwidth / 2,
global_dirty_limit / DIRTY_SCOPE);
pages = min(pages, work->nr_pages);
pages = round_down(pages + MIN_WRITEBACK_PAGES,
@@ -725,7 +725,7 @@ static long writeback_sb_inodes(struct super_block *sb,
inode->i_state |= I_SYNC;
spin_unlock(&inode->i_lock);

- write_chunk = writeback_chunk_size(wb->bdi, work);
+ write_chunk = writeback_chunk_size(wb, work);
wbc.nr_to_write = write_chunk;
wbc.pages_skipped = 0;

@@ -812,7 +812,7 @@ static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
return nr_pages - work.nr_pages;
}

-static bool over_bground_thresh(struct backing_dev_info *bdi)
+static bool over_bground_thresh(struct bdi_writeback *wb)
{
unsigned long background_thresh, dirty_thresh;

@@ -822,8 +822,7 @@ static bool over_bground_thresh(struct backing_dev_info *bdi)
global_page_state(NR_UNSTABLE_NFS) > background_thresh)
return true;

- if (wb_stat(&bdi->wb, WB_RECLAIMABLE) >
- bdi_dirty_limit(bdi, background_thresh))
+ if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh))
return true;

return false;
@@ -836,7 +835,7 @@ static bool over_bground_thresh(struct backing_dev_info *bdi)
static void wb_update_bandwidth(struct bdi_writeback *wb,
unsigned long start_time)
{
- __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time);
+ __wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time);
}

/*
@@ -888,7 +887,7 @@ static long wb_writeback(struct bdi_writeback *wb,
* For background writeout, stop when we are below the
* background dirty threshold
*/
- if (work->for_background && !over_bground_thresh(wb->bdi))
+ if (work->for_background && !over_bground_thresh(wb))
break;

/*
@@ -980,7 +979,7 @@ static unsigned long get_nr_dirty_pages(void)

static long wb_check_background_flush(struct bdi_writeback *wb)
{
- if (over_bground_thresh(wb->bdi)) {
+ if (over_bground_thresh(wb)) {

struct wb_writeback_work work = {
.nr_pages = LONG_MAX,
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 1666382..5b4c4d35 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -748,7 +748,7 @@ static int gfs2_write_inode(struct inode *inode, struct writeback_control *wbc)

if (wbc->sync_mode == WB_SYNC_ALL)
gfs2_log_flush(GFS2_SB(inode), ip->i_gl, NORMAL_FLUSH);
- if (bdi->dirty_exceeded)
+ if (bdi->wb.dirty_exceeded)
gfs2_ail1_flush(sdp, wbc);
else
filemap_fdatawrite(metamapping);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index fe7a907..2ab0604 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -60,16 +60,6 @@ struct bdi_writeback {
spinlock_t list_lock; /* protects the b_* lists */

struct percpu_counter stat[NR_WB_STAT_ITEMS];
-};
-
-struct backing_dev_info {
- struct list_head bdi_list;
- unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
- unsigned int capabilities; /* Device capabilities */
- congested_fn *congested_fn; /* Function pointer if device is md/dm */
- void *congested_data; /* Pointer to aux data for congested func */
-
- char *name;

unsigned long bw_time_stamp; /* last time write bw is updated */
unsigned long dirtied_stamp;
@@ -88,6 +78,16 @@ struct backing_dev_info {

struct fprop_local_percpu completions;
int dirty_exceeded;
+};
+
+struct backing_dev_info {
+ struct list_head bdi_list;
+ unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
+ unsigned int capabilities; /* Device capabilities */
+ congested_fn *congested_fn; /* Function pointer if device is md/dm */
+ void *congested_data; /* Pointer to aux data for congested func */
+
+ char *name;

unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 0004833..8e4485f 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -152,16 +152,15 @@ int dirty_writeback_centisecs_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);

void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
-unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
- unsigned long dirty);
-
-void __bdi_update_bandwidth(struct backing_dev_info *bdi,
- unsigned long thresh,
- unsigned long bg_thresh,
- unsigned long dirty,
- unsigned long bdi_thresh,
- unsigned long bdi_dirty,
- unsigned long start_time);
+unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty);
+
+void __wb_update_bandwidth(struct bdi_writeback *wb,
+ unsigned long thresh,
+ unsigned long bg_thresh,
+ unsigned long dirty,
+ unsigned long bdi_thresh,
+ unsigned long bdi_dirty,
+ unsigned long start_time);

void page_writeback_init(void);
void balance_dirty_pages_ratelimited(struct address_space *mapping);
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 5a14ead..5c9a68c 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -383,13 +383,13 @@ TRACE_EVENT(bdi_dirty_ratelimit,

TP_fast_assign(
strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
- __entry->write_bw = KBps(bdi->write_bandwidth);
- __entry->avg_write_bw = KBps(bdi->avg_write_bandwidth);
+ __entry->write_bw = KBps(bdi->wb.write_bandwidth);
+ __entry->avg_write_bw = KBps(bdi->wb.avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
- __entry->dirty_ratelimit = KBps(bdi->dirty_ratelimit);
+ __entry->dirty_ratelimit = KBps(bdi->wb.dirty_ratelimit);
__entry->task_ratelimit = KBps(task_ratelimit);
__entry->balanced_dirty_ratelimit =
- KBps(bdi->balanced_dirty_ratelimit);
+ KBps(bdi->wb.balanced_dirty_ratelimit);
),

TP_printk("bdi %s: "
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 7b1d191..9a6c472 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -66,7 +66,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
spin_unlock(&wb->list_lock);

global_dirty_limits(&background_thresh, &dirty_thresh);
- bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
+ bdi_thresh = wb_dirty_limit(wb, dirty_thresh);

#define K(x) ((x) << (PAGE_SHIFT - 10))
seq_printf(m,
@@ -91,7 +91,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
K(background_thresh),
(unsigned long) K(wb_stat(wb, WB_DIRTIED)),
(unsigned long) K(wb_stat(wb, WB_WRITTEN)),
- (unsigned long) K(bdi->write_bandwidth),
+ (unsigned long) K(wb->write_bandwidth),
nr_dirty,
nr_io,
nr_more_io,
@@ -376,6 +376,11 @@ void bdi_unregister(struct backing_dev_info *bdi)
}
EXPORT_SYMBOL(bdi_unregister);

+/*
+ * Initial write bandwidth: 100 MB/s
+ */
+#define INIT_BW (100 << (20 - PAGE_SHIFT))
+
static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
{
int i, err;
@@ -391,11 +396,22 @@ static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
spin_lock_init(&wb->list_lock);
INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);

+ wb->bw_time_stamp = jiffies;
+ wb->balanced_dirty_ratelimit = INIT_BW;
+ wb->dirty_ratelimit = INIT_BW;
+ wb->write_bandwidth = INIT_BW;
+ wb->avg_write_bandwidth = INIT_BW;
+
+ err = fprop_local_init_percpu(&wb->completions, GFP_KERNEL);
+ if (err)
+ return err;
+
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]);
+ fprop_local_destroy_percpu(&wb->completions);
return err;
}
}
@@ -411,12 +427,9 @@ static void bdi_wb_exit(struct bdi_writeback *wb)

for (i = 0; i < NR_WB_STAT_ITEMS; i++)
percpu_counter_destroy(&wb->stat[i]);
-}

-/*
- * Initial write bandwidth: 100 MB/s
- */
-#define INIT_BW (100 << (20 - PAGE_SHIFT))
+ fprop_local_destroy_percpu(&wb->completions);
+}

int bdi_init(struct backing_dev_info *bdi)
{
@@ -435,22 +448,6 @@ int bdi_init(struct backing_dev_info *bdi)
if (err)
return err;

- bdi->dirty_exceeded = 0;
-
- bdi->bw_time_stamp = jiffies;
- bdi->written_stamp = 0;
-
- bdi->balanced_dirty_ratelimit = INIT_BW;
- bdi->dirty_ratelimit = INIT_BW;
- bdi->write_bandwidth = INIT_BW;
- bdi->avg_write_bandwidth = INIT_BW;
-
- err = fprop_local_init_percpu(&bdi->completions, GFP_KERNEL);
- if (err) {
- bdi_wb_exit(&bdi->wb);
- return err;
- }
-
return 0;
}
EXPORT_SYMBOL(bdi_init);
@@ -468,8 +465,6 @@ void bdi_destroy(struct backing_dev_info *bdi)
}

bdi_wb_exit(&bdi->wb);
-
- fprop_local_destroy_percpu(&bdi->completions);
}
EXPORT_SYMBOL(bdi_destroy);

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index af3edb6..29fb4f3 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -399,7 +399,7 @@ static unsigned long wp_next_time(unsigned long cur_time)
static inline void __wb_writeout_inc(struct bdi_writeback *wb)
{
__inc_wb_stat(wb, WB_WRITTEN);
- __fprop_inc_percpu_max(&writeout_completions, &wb->bdi->completions,
+ __fprop_inc_percpu_max(&writeout_completions, &wb->completions,
wb->bdi->max_prop_frac);
/* First event after period switching was turned off? */
if (!unlikely(writeout_period_time)) {
@@ -427,10 +427,10 @@ EXPORT_SYMBOL_GPL(wb_writeout_inc);
/*
* Obtain an accurate fraction of the BDI's portion.
*/
-static void bdi_writeout_fraction(struct backing_dev_info *bdi,
- long *numerator, long *denominator)
+static void wb_writeout_fraction(struct bdi_writeback *wb,
+ long *numerator, long *denominator)
{
- fprop_fraction_percpu(&writeout_completions, &bdi->completions,
+ fprop_fraction_percpu(&writeout_completions, &wb->completions,
numerator, denominator);
}

@@ -516,11 +516,11 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
}

/**
- * bdi_dirty_limit - @bdi's share of dirty throttling threshold
- * @bdi: the backing_dev_info to query
+ * wb_dirty_limit - @wb's share of dirty throttling threshold
+ * @wb: bdi_writeback to query
* @dirty: global dirty limit in pages
*
- * Returns @bdi's dirty limit in pages. The term "dirty" in the context of
+ * Returns @wb's dirty limit in pages. The term "dirty" in the context of
* dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages.
*
* Note that balance_dirty_pages() will only seriously take it as a hard limit
@@ -528,34 +528,35 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
* control. For example, when the device is completely stalled due to some error
* conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key.
* In the other normal situations, it acts more gently by throttling the tasks
- * more (rather than completely block them) when the bdi dirty pages go high.
+ * more (rather than completely block them) when the wb dirty pages go high.
*
* It allocates high/low dirty limits to fast/slow devices, in order to prevent
* - starving fast devices
* - piling up dirty pages (that will take long time to sync) on slow devices
*
- * The bdi's share of dirty limit will be adapting to its throughput and
+ * The wb's share of dirty limit will be adapting to its throughput and
* bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
*/
-unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty)
+unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
{
- u64 bdi_dirty;
+ struct backing_dev_info *bdi = wb->bdi;
+ u64 wb_dirty;
long numerator, denominator;

/*
* Calculate this BDI's share of the dirty ratio.
*/
- bdi_writeout_fraction(bdi, &numerator, &denominator);
+ wb_writeout_fraction(wb, &numerator, &denominator);

- bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100;
- bdi_dirty *= numerator;
- do_div(bdi_dirty, denominator);
+ wb_dirty = (dirty * (100 - bdi_min_ratio)) / 100;
+ wb_dirty *= numerator;
+ do_div(wb_dirty, denominator);

- bdi_dirty += (dirty * bdi->min_ratio) / 100;
- if (bdi_dirty > (dirty * bdi->max_ratio) / 100)
- bdi_dirty = dirty * bdi->max_ratio / 100;
+ wb_dirty += (dirty * bdi->min_ratio) / 100;
+ if (wb_dirty > (dirty * bdi->max_ratio) / 100)
+ wb_dirty = dirty * bdi->max_ratio / 100;

- return bdi_dirty;
+ return wb_dirty;
}

/*
@@ -664,14 +665,14 @@ static long long pos_ratio_polynom(unsigned long setpoint,
* card's bdi_dirty may rush to many times higher than bdi_setpoint.
* - the bdi dirty thresh drops quickly due to change of JBOD workload
*/
-static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
- unsigned long thresh,
- unsigned long bg_thresh,
- unsigned long dirty,
- unsigned long bdi_thresh,
- unsigned long bdi_dirty)
+static unsigned long wb_position_ratio(struct bdi_writeback *wb,
+ unsigned long thresh,
+ unsigned long bg_thresh,
+ unsigned long dirty,
+ unsigned long bdi_thresh,
+ unsigned long bdi_dirty)
{
- unsigned long write_bw = bdi->avg_write_bandwidth;
+ unsigned long write_bw = wb->avg_write_bandwidth;
unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh);
unsigned long limit = hard_dirty_limit(thresh);
unsigned long x_intercept;
@@ -702,12 +703,12 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
* consume arbitrary amount of RAM because it is accounted in
* NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty".
*
- * Here, in bdi_position_ratio(), we calculate pos_ratio based on
+ * Here, in wb_position_ratio(), we calculate pos_ratio based on
* two values: bdi_dirty and bdi_thresh. Let's consider an example:
* total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global
* limits are set by default to 10% and 20% (background and throttle).
* Then bdi_thresh is 1% of 20% of 16GB. This amounts to ~8K pages.
- * bdi_dirty_limit(bdi, bg_thresh) is about ~4K pages. bdi_setpoint is
+ * wb_dirty_limit(wb, bg_thresh) is about ~4K pages. bdi_setpoint is
* about ~6K pages (as the average of background and throttle bdi
* limits). The 3rd order polynomial will provide positive feedback if
* bdi_dirty is under bdi_setpoint and vice versa.
@@ -717,7 +718,7 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
* much earlier than global "freerun" is reached (~23MB vs. ~2.3GB
* in the example above).
*/
- if (unlikely(bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
+ if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
long long bdi_pos_ratio;
unsigned long bdi_bg_thresh;

@@ -842,13 +843,13 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
return pos_ratio;
}

-static void bdi_update_write_bandwidth(struct backing_dev_info *bdi,
- unsigned long elapsed,
- unsigned long written)
+static void wb_update_write_bandwidth(struct bdi_writeback *wb,
+ unsigned long elapsed,
+ unsigned long written)
{
const unsigned long period = roundup_pow_of_two(3 * HZ);
- unsigned long avg = bdi->avg_write_bandwidth;
- unsigned long old = bdi->write_bandwidth;
+ unsigned long avg = wb->avg_write_bandwidth;
+ unsigned long old = wb->write_bandwidth;
u64 bw;

/*
@@ -861,14 +862,14 @@ static void bdi_update_write_bandwidth(struct backing_dev_info *bdi,
* @written may have decreased due to account_page_redirty().
* Avoid underflowing @bw calculation.
*/
- bw = written - min(written, bdi->written_stamp);
+ bw = written - min(written, wb->written_stamp);
bw *= HZ;
if (unlikely(elapsed > period)) {
do_div(bw, elapsed);
avg = bw;
goto out;
}
- bw += (u64)bdi->write_bandwidth * (period - elapsed);
+ bw += (u64)wb->write_bandwidth * (period - elapsed);
bw >>= ilog2(period);

/*
@@ -881,8 +882,8 @@ static void bdi_update_write_bandwidth(struct backing_dev_info *bdi,
avg += (old - avg) >> 3;

out:
- bdi->write_bandwidth = bw;
- bdi->avg_write_bandwidth = avg;
+ wb->write_bandwidth = bw;
+ wb->avg_write_bandwidth = avg;
}

/*
@@ -947,20 +948,20 @@ static void global_update_bandwidth(unsigned long thresh,
* Normal bdi tasks will be curbed at or below it in long term.
* Obviously it should be around (write_bw / N) when there are N dd tasks.
*/
-static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
- unsigned long thresh,
- unsigned long bg_thresh,
- unsigned long dirty,
- unsigned long bdi_thresh,
- unsigned long bdi_dirty,
- unsigned long dirtied,
- unsigned long elapsed)
+static void wb_update_dirty_ratelimit(struct bdi_writeback *wb,
+ unsigned long thresh,
+ unsigned long bg_thresh,
+ unsigned long dirty,
+ unsigned long bdi_thresh,
+ unsigned long bdi_dirty,
+ unsigned long dirtied,
+ unsigned long elapsed)
{
unsigned long freerun = dirty_freerun_ceiling(thresh, bg_thresh);
unsigned long limit = hard_dirty_limit(thresh);
unsigned long setpoint = (freerun + limit) / 2;
- unsigned long write_bw = bdi->avg_write_bandwidth;
- unsigned long dirty_ratelimit = bdi->dirty_ratelimit;
+ unsigned long write_bw = wb->avg_write_bandwidth;
+ unsigned long dirty_ratelimit = wb->dirty_ratelimit;
unsigned long dirty_rate;
unsigned long task_ratelimit;
unsigned long balanced_dirty_ratelimit;
@@ -972,10 +973,10 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
* The dirty rate will match the writeout rate in long term, except
* when dirty pages are truncated by userspace or re-dirtied by FS.
*/
- dirty_rate = (dirtied - bdi->dirtied_stamp) * HZ / elapsed;
+ dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed;

- pos_ratio = bdi_position_ratio(bdi, thresh, bg_thresh, dirty,
- bdi_thresh, bdi_dirty);
+ pos_ratio = wb_position_ratio(wb, thresh, bg_thresh, dirty,
+ bdi_thresh, bdi_dirty);
/*
* task_ratelimit reflects each dd's dirty rate for the past 200ms.
*/
@@ -1059,31 +1060,31 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,

/*
* For strictlimit case, calculations above were based on bdi counters
- * and limits (starting from pos_ratio = bdi_position_ratio() and up to
+ * and limits (starting from pos_ratio = wb_position_ratio() and up to
* balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate).
* Hence, to calculate "step" properly, we have to use bdi_dirty as
* "dirty" and bdi_setpoint as "setpoint".
*
* We rampup dirty_ratelimit forcibly if bdi_dirty is low because
* it's possible that bdi_thresh is close to zero due to inactivity
- * of backing device (see the implementation of bdi_dirty_limit()).
+ * of backing device (see the implementation of wb_dirty_limit()).
*/
- if (unlikely(bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
+ if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
dirty = bdi_dirty;
if (bdi_dirty < 8)
setpoint = bdi_dirty + 1;
else
setpoint = (bdi_thresh +
- bdi_dirty_limit(bdi, bg_thresh)) / 2;
+ wb_dirty_limit(wb, bg_thresh)) / 2;
}

if (dirty < setpoint) {
- x = min3(bdi->balanced_dirty_ratelimit,
+ x = min3(wb->balanced_dirty_ratelimit,
balanced_dirty_ratelimit, task_ratelimit);
if (dirty_ratelimit < x)
step = x - dirty_ratelimit;
} else {
- x = max3(bdi->balanced_dirty_ratelimit,
+ x = max3(wb->balanced_dirty_ratelimit,
balanced_dirty_ratelimit, task_ratelimit);
if (dirty_ratelimit > x)
step = dirty_ratelimit - x;
@@ -1105,22 +1106,22 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
else
dirty_ratelimit -= step;

- bdi->dirty_ratelimit = max(dirty_ratelimit, 1UL);
- bdi->balanced_dirty_ratelimit = balanced_dirty_ratelimit;
+ wb->dirty_ratelimit = max(dirty_ratelimit, 1UL);
+ wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit;

- trace_bdi_dirty_ratelimit(bdi, dirty_rate, task_ratelimit);
+ trace_bdi_dirty_ratelimit(wb->bdi, dirty_rate, task_ratelimit);
}

-void __bdi_update_bandwidth(struct backing_dev_info *bdi,
- unsigned long thresh,
- unsigned long bg_thresh,
- unsigned long dirty,
- unsigned long bdi_thresh,
- unsigned long bdi_dirty,
- unsigned long start_time)
+void __wb_update_bandwidth(struct bdi_writeback *wb,
+ unsigned long thresh,
+ unsigned long bg_thresh,
+ unsigned long dirty,
+ unsigned long bdi_thresh,
+ unsigned long bdi_dirty,
+ unsigned long start_time)
{
unsigned long now = jiffies;
- unsigned long elapsed = now - bdi->bw_time_stamp;
+ unsigned long elapsed = now - wb->bw_time_stamp;
unsigned long dirtied;
unsigned long written;

@@ -1130,44 +1131,44 @@ void __bdi_update_bandwidth(struct backing_dev_info *bdi,
if (elapsed < BANDWIDTH_INTERVAL)
return;

- dirtied = percpu_counter_read(&bdi->wb.stat[WB_DIRTIED]);
- written = percpu_counter_read(&bdi->wb.stat[WB_WRITTEN]);
+ dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]);
+ written = percpu_counter_read(&wb->stat[WB_WRITTEN]);

/*
* Skip quiet periods when disk bandwidth is under-utilized.
* (at least 1s idle time between two flusher runs)
*/
- if (elapsed > HZ && time_before(bdi->bw_time_stamp, start_time))
+ if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time))
goto snapshot;

if (thresh) {
global_update_bandwidth(thresh, dirty, now);
- bdi_update_dirty_ratelimit(bdi, thresh, bg_thresh, dirty,
- bdi_thresh, bdi_dirty,
- dirtied, elapsed);
+ wb_update_dirty_ratelimit(wb, thresh, bg_thresh, dirty,
+ bdi_thresh, bdi_dirty,
+ dirtied, elapsed);
}
- bdi_update_write_bandwidth(bdi, elapsed, written);
+ wb_update_write_bandwidth(wb, elapsed, written);

snapshot:
- bdi->dirtied_stamp = dirtied;
- bdi->written_stamp = written;
- bdi->bw_time_stamp = now;
+ wb->dirtied_stamp = dirtied;
+ wb->written_stamp = written;
+ wb->bw_time_stamp = now;
}

-static void bdi_update_bandwidth(struct backing_dev_info *bdi,
- unsigned long thresh,
- unsigned long bg_thresh,
- unsigned long dirty,
- unsigned long bdi_thresh,
- unsigned long bdi_dirty,
- unsigned long start_time)
+static void wb_update_bandwidth(struct bdi_writeback *wb,
+ unsigned long thresh,
+ unsigned long bg_thresh,
+ unsigned long dirty,
+ unsigned long bdi_thresh,
+ unsigned long bdi_dirty,
+ unsigned long start_time)
{
- if (time_is_after_eq_jiffies(bdi->bw_time_stamp + BANDWIDTH_INTERVAL))
+ if (time_is_after_eq_jiffies(wb->bw_time_stamp + BANDWIDTH_INTERVAL))
return;
- spin_lock(&bdi->wb.list_lock);
- __bdi_update_bandwidth(bdi, thresh, bg_thresh, dirty,
- bdi_thresh, bdi_dirty, start_time);
- spin_unlock(&bdi->wb.list_lock);
+ spin_lock(&wb->list_lock);
+ __wb_update_bandwidth(wb, thresh, bg_thresh, dirty,
+ bdi_thresh, bdi_dirty, start_time);
+ spin_unlock(&wb->list_lock);
}

/*
@@ -1187,10 +1188,10 @@ static unsigned long dirty_poll_interval(unsigned long dirty,
return 1;
}

-static unsigned long bdi_max_pause(struct backing_dev_info *bdi,
- unsigned long bdi_dirty)
+static unsigned long wb_max_pause(struct bdi_writeback *wb,
+ unsigned long bdi_dirty)
{
- unsigned long bw = bdi->avg_write_bandwidth;
+ unsigned long bw = wb->avg_write_bandwidth;
unsigned long t;

/*
@@ -1206,14 +1207,14 @@ static unsigned long bdi_max_pause(struct backing_dev_info *bdi,
return min_t(unsigned long, t, MAX_PAUSE);
}

-static long bdi_min_pause(struct backing_dev_info *bdi,
- long max_pause,
- unsigned long task_ratelimit,
- unsigned long dirty_ratelimit,
- int *nr_dirtied_pause)
+static long wb_min_pause(struct bdi_writeback *wb,
+ long max_pause,
+ unsigned long task_ratelimit,
+ unsigned long dirty_ratelimit,
+ int *nr_dirtied_pause)
{
- long hi = ilog2(bdi->avg_write_bandwidth);
- long lo = ilog2(bdi->dirty_ratelimit);
+ long hi = ilog2(wb->avg_write_bandwidth);
+ long lo = ilog2(wb->dirty_ratelimit);
long t; /* target pause */
long pause; /* estimated next pause */
int pages; /* target nr_dirtied_pause */
@@ -1281,14 +1282,13 @@ static long bdi_min_pause(struct backing_dev_info *bdi,
return pages >= DIRTY_POLL_THRESH ? 1 + t / 2 : t;
}

-static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
- unsigned long dirty_thresh,
- unsigned long background_thresh,
- unsigned long *bdi_dirty,
- unsigned long *bdi_thresh,
- unsigned long *bdi_bg_thresh)
+static inline void wb_dirty_limits(struct bdi_writeback *wb,
+ unsigned long dirty_thresh,
+ unsigned long background_thresh,
+ unsigned long *bdi_dirty,
+ unsigned long *bdi_thresh,
+ unsigned long *bdi_bg_thresh)
{
- struct bdi_writeback *wb = &bdi->wb;
unsigned long wb_reclaimable;

/*
@@ -1301,10 +1301,10 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
* In this case we don't want to hard throttle the USB key
* dirtiers for 100 seconds until bdi_dirty drops under
* bdi_thresh. Instead the auxiliary bdi control line in
- * bdi_position_ratio() will let the dirtier task progress
+ * wb_position_ratio() will let the dirtier task progress
* at some rate <= (write_bw / 2) for bringing down bdi_dirty.
*/
- *bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
+ *bdi_thresh = wb_dirty_limit(wb, dirty_thresh);

if (bdi_bg_thresh)
*bdi_bg_thresh = dirty_thresh ? div_u64((u64)*bdi_thresh *
@@ -1354,6 +1354,7 @@ static void balance_dirty_pages(struct address_space *mapping,
unsigned long dirty_ratelimit;
unsigned long pos_ratio;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+ struct bdi_writeback *wb = &bdi->wb;
bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
unsigned long start_time = jiffies;

@@ -1378,8 +1379,8 @@ static void balance_dirty_pages(struct address_space *mapping,
global_dirty_limits(&background_thresh, &dirty_thresh);

if (unlikely(strictlimit)) {
- bdi_dirty_limits(bdi, dirty_thresh, background_thresh,
- &bdi_dirty, &bdi_thresh, &bg_thresh);
+ wb_dirty_limits(wb, dirty_thresh, background_thresh,
+ &bdi_dirty, &bdi_thresh, &bg_thresh);

dirty = bdi_dirty;
thresh = bdi_thresh;
@@ -1410,28 +1411,28 @@ static void balance_dirty_pages(struct address_space *mapping,
bdi_start_background_writeback(bdi);

if (!strictlimit)
- bdi_dirty_limits(bdi, dirty_thresh, background_thresh,
- &bdi_dirty, &bdi_thresh, NULL);
+ wb_dirty_limits(wb, dirty_thresh, background_thresh,
+ &bdi_dirty, &bdi_thresh, NULL);

dirty_exceeded = (bdi_dirty > bdi_thresh) &&
((nr_dirty > dirty_thresh) || strictlimit);
- if (dirty_exceeded && !bdi->dirty_exceeded)
- bdi->dirty_exceeded = 1;
+ if (dirty_exceeded && !wb->dirty_exceeded)
+ wb->dirty_exceeded = 1;

- bdi_update_bandwidth(bdi, dirty_thresh, background_thresh,
- nr_dirty, bdi_thresh, bdi_dirty,
- start_time);
+ wb_update_bandwidth(wb, dirty_thresh, background_thresh,
+ nr_dirty, bdi_thresh, bdi_dirty,
+ start_time);

- dirty_ratelimit = bdi->dirty_ratelimit;
- pos_ratio = bdi_position_ratio(bdi, dirty_thresh,
- background_thresh, nr_dirty,
- bdi_thresh, bdi_dirty);
+ dirty_ratelimit = wb->dirty_ratelimit;
+ pos_ratio = wb_position_ratio(wb, dirty_thresh,
+ background_thresh, nr_dirty,
+ bdi_thresh, bdi_dirty);
task_ratelimit = ((u64)dirty_ratelimit * pos_ratio) >>
RATELIMIT_CALC_SHIFT;
- max_pause = bdi_max_pause(bdi, bdi_dirty);
- min_pause = bdi_min_pause(bdi, max_pause,
- task_ratelimit, dirty_ratelimit,
- &nr_dirtied_pause);
+ max_pause = wb_max_pause(wb, bdi_dirty);
+ min_pause = wb_min_pause(wb, max_pause,
+ task_ratelimit, dirty_ratelimit,
+ &nr_dirtied_pause);

if (unlikely(task_ratelimit == 0)) {
period = max_pause;
@@ -1515,15 +1516,15 @@ pause:
* more page. However bdi_dirty has accounting errors. So use
* the larger and more IO friendly wb_stat_error.
*/
- if (bdi_dirty <= wb_stat_error(&bdi->wb))
+ if (bdi_dirty <= wb_stat_error(wb))
break;

if (fatal_signal_pending(current))
break;
}

- if (!dirty_exceeded && bdi->dirty_exceeded)
- bdi->dirty_exceeded = 0;
+ if (!dirty_exceeded && wb->dirty_exceeded)
+ wb->dirty_exceeded = 0;

if (writeback_in_progress(bdi))
return;
@@ -1577,6 +1578,7 @@ DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
void balance_dirty_pages_ratelimited(struct address_space *mapping)
{
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+ struct bdi_writeback *wb = &bdi->wb;
int ratelimit;
int *p;

@@ -1584,7 +1586,7 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
return;

ratelimit = current->nr_dirtied_pause;
- if (bdi->dirty_exceeded)
+ if (wb->dirty_exceeded)
ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10));

preempt_disable();
--
2.1.0