From: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
This commit introduce a new sysfs file:
/sys/block/bcache0/bcache/writeback_inflight (read only)
/sys/block/bcache0/bcache/writeback_inflight_max (read write)
(1) read the writeback_inflight will output the current inflight writeback op.
(2）read the writeback_inflight_max will output the max number of writeback inflight.
(3) write the writeback_inflight_max can set the max number of writeback inflight,
valid range is [1, INT_MAX).
E.g:
$ ll /sys/block/bcache0/bcache/writeback_inflight*
-r--r--r-- 1 root root 4096 Oct 27 08:45 /sys/block/bcache0/bcache/writeback_inflight
-rw-r--r-- 1 root root 4096 Oct 27 08:45 /sys/block/bcache0/bcache/writeback_inflight_max
$ cat /sys/block/bcache0/bcache/writeback_inflight
0
$ cat /sys/block/bcache0/bcache/writeback_inflight_max
64
$ echo 1024 > /sys/block/bcache0/bcache/writeback_inflight_max
$ cat /sys/block/bcache0/bcache/writeback_inflight_max
1024
Signed-off-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
Signed-off-by: mingzhe <mingzhe.zou@xxxxxxxxxxxx>
---
drivers/md/bcache/bcache.h | 6 ++++-
drivers/md/bcache/sysfs.c | 21 +++++++++++++++++
drivers/md/bcache/writeback.c | 43 ++++++++++++++++++++++++++++++++---
3 files changed, 66 insertions(+), 4 deletions(-)
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index aebb7ef10e63..74434a7730bb 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -337,7 +337,11 @@ struct cached_dev {
struct delayed_work writeback_rate_update;
/* Limit number of writeback bios in flight */
- struct semaphore in_flight;
+ atomic_t wb_inflight;
+ unsigned long wb_inflight_max;
+ spinlock_t wb_inflight_lock;
+ wait_queue_head_t wb_inflight_wait;
+
struct task_struct *writeback_thread;
struct workqueue_struct *writeback_write_wq;
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index c6f677059214..0382b70c29d5 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -119,6 +119,9 @@ rw_attribute(writeback_delay);
rw_attribute(writeback_rate);
rw_attribute(writeback_consider_fragment);
+read_attribute(writeback_inflight);
+rw_attribute(writeback_inflight_max);
+
rw_attribute(writeback_rate_update_seconds);
rw_attribute(writeback_rate_i_term_inverse);
rw_attribute(writeback_rate_p_term_inverse);
@@ -201,6 +204,8 @@ SHOW(__bch_cached_dev)
var_printf(writeback_consider_fragment, "%i");
var_print(writeback_delay);
var_print(writeback_percent);
+ sysfs_printf(writeback_inflight, "%i", atomic_read(&dc->wb_inflight));
+ sysfs_printf(writeback_inflight_max, "%li", dc->wb_inflight_max);
sysfs_hprint(writeback_rate,
wb ? atomic_long_read(&dc->writeback_rate.rate) << 9 : 0);
sysfs_printf(io_errors, "%i", atomic_read(&dc->io_errors));
@@ -448,6 +453,20 @@ STORE(__cached_dev)
if (attr == &sysfs_detach && dc->disk.c)
bch_cached_dev_detach(dc);
+ if (attr == &sysfs_writeback_inflight_max) {
+ ssize_t ret;
+ unsigned long v;
+
+ ret = strtoul_safe_clamp(buf, v, 1, INT_MAX);
+ if (ret)
+ return ret;
+
+ spin_lock(&dc->wb_inflight_lock);
+ dc->wb_inflight_max = v;
+ spin_unlock(&dc->wb_inflight_lock);
+ wake_up(&dc->wb_inflight_wait);
+ }
+
if (attr == &sysfs_stop)
bcache_device_stop(&dc->disk);
@@ -514,6 +533,8 @@ static struct attribute *bch_cached_dev_attrs[] = {
&sysfs_writeback_running,
&sysfs_writeback_delay,
&sysfs_writeback_percent,
+ &sysfs_writeback_inflight,
+ &sysfs_writeback_inflight_max,
&sysfs_writeback_rate,
&sysfs_writeback_consider_fragment,
&sysfs_writeback_rate_update_seconds,
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index d4a5fc0650bb..0c5f25816e2e 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -348,6 +348,7 @@ static void dirty_io_destructor(struct closure *cl)
kfree(io);
}
+static void end_wb_inflight(struct cached_dev *dc);
static void write_dirty_finish(struct closure *cl)
{
struct dirty_io *io = container_of(cl, struct dirty_io, cl);
@@ -382,7 +383,7 @@ static void write_dirty_finish(struct closure *cl)
}
bch_keybuf_del(&dc->writeback_keys, w);
- up(&dc->in_flight);
+ end_wb_inflight(dc);
closure_return_with_destructor(cl, dirty_io_destructor);
}
@@ -471,6 +472,38 @@ static void read_dirty_submit(struct closure *cl)
continue_at(cl, write_dirty, io->dc->writeback_write_wq);
}
+static void start_wb_inflight(struct cached_dev *dc)
+{
+ DEFINE_WAIT(w);
+
+ spin_lock(&dc->wb_inflight_lock);
+ if (atomic_read(&dc->wb_inflight) < dc->wb_inflight_max)
+ goto out;
+
+ do {
+ prepare_to_wait(&dc->wb_inflight_wait, &w,
+ TASK_UNINTERRUPTIBLE);
+
+ spin_unlock(&dc->wb_inflight_lock);
+ schedule();
+ spin_lock(&dc->wb_inflight_lock);
+ } while (atomic_read(&dc->wb_inflight) >= dc->wb_inflight_max);
+
+ finish_wait(&dc->wb_inflight_wait, &w);
+
+out:
+ BUG_ON(atomic_inc_return(&dc->wb_inflight) > dc->wb_inflight_max);
+ spin_unlock(&dc->wb_inflight_lock);
+}
+
+static void end_wb_inflight(struct cached_dev *dc)
+{
+ spin_lock(&dc->wb_inflight_lock);
+ BUG_ON(atomic_dec_return(&dc->wb_inflight) < 0);
+ spin_unlock(&dc->wb_inflight_lock);
+ wake_up(&dc->wb_inflight_wait);
+}
+
static void read_dirty(struct cached_dev *dc)
{
unsigned int delay = 0;
@@ -557,7 +590,7 @@ static void read_dirty(struct cached_dev *dc)
trace_bcache_writeback(&w->key);
- down(&dc->in_flight);
+ start_wb_inflight(dc);
/*
* We've acquired a semaphore for the maximum
@@ -1025,7 +1058,11 @@ void bch_sectors_dirty_init(struct bcache_device *d)
void bch_cached_dev_writeback_init(struct cached_dev *dc)
{
- sema_init(&dc->in_flight, 64);
+ atomic_set(&dc->wb_inflight, 0);
+ dc->wb_inflight_max = 64;
+ spin_lock_init(&dc->wb_inflight_lock);
+ init_waitqueue_head(&dc->wb_inflight_wait);
+
init_rwsem(&dc->writeback_lock);
bch_keybuf_init(&dc->writeback_keys);
--
2.17.1
