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From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: miklos@szeredi.hu, ktkhai@virtuozzo.com, linux-fsdevel@vger.kernel.org
Subject: [PATCH 5/6] fs: Introduce fuse_conn::bg_lock
Date: Mon, 27 Aug 2018 18:29:46 +0300	[thread overview]
Message-ID: <153538378685.18303.16396611744482855136.stgit@localhost.localdomain> (raw)
In-Reply-To: <153538208536.18303.10732945923322972743.stgit@localhost.localdomain>

To reduce contention of fuse_conn::lock, this patch
introduces bg_lock for protection of fields related
to background queue. These are: max_background,
congestion_threshold, num_background, active_background,
bg_queue and blocked.

This allows next patch to make async reads not requiring
fuse_conn::lock, so async reads and writes will have
better performance executed in parallel.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 fs/fuse/control.c |    8 ++++----
 fs/fuse/dev.c     |   20 ++++++++++++--------
 fs/fuse/file.c    |    2 +-
 fs/fuse/fuse_i.h  |    8 ++++++--
 fs/fuse/inode.c   |    3 +++
 5 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 9206501bd94d..63d0e9552140 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -125,12 +125,12 @@ static ssize_t fuse_conn_max_background_write(struct file *file,
 	if (ret > 0) {
 		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
 		if (fc) {
-			spin_lock(&fc->lock);
+			spin_lock(&fc->bg_lock);
 			fc->max_background = val;
 			fc->blocked = (fc->num_background >= fc->max_background);
 			if (!fc->blocked && waitqueue_active(&fc->blocked_waitq))
 				wake_up(&fc->blocked_waitq);
-			spin_unlock(&fc->lock);
+			spin_unlock(&fc->bg_lock);
 			fuse_conn_put(fc);
 		}
 	}
@@ -171,7 +171,7 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
 	if (!fc)
 		goto out;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fc->bg_lock);
 	fc->congestion_threshold = val;
 	if (fc->sb) {
 		if (fc->num_background < fc->congestion_threshold) {
@@ -182,7 +182,7 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
 			set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
 		}
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fc->bg_lock);
 	fuse_conn_put(fc);
 out:
 	return ret;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index ce07a41ff8fe..9690e7c79df7 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -287,10 +287,10 @@ void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
 			 * We get here in the unlikely case that a background
 			 * request was allocated but not sent
 			 */
-			spin_lock(&fc->lock);
+			spin_lock(&fc->bg_lock);
 			if (!fc->blocked)
 				wake_up(&fc->blocked_waitq);
-			spin_unlock(&fc->lock);
+			spin_unlock(&fc->bg_lock);
 		}
 
 		if (test_bit(FR_WAITING, &req->flags)) {
@@ -391,7 +391,7 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
 	WARN_ON(test_bit(FR_SENT, &req->flags));
 	if (test_bit(FR_BACKGROUND, &req->flags)) {
 		clear_bit(FR_BACKGROUND, &req->flags);
-		spin_lock(&fc->lock);
+		spin_lock(&fc->bg_lock);
 		if (fc->num_background == fc->max_background)
 			fc->blocked = 0;
 
@@ -406,7 +406,7 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
 		fc->num_background--;
 		fc->active_background--;
 		flush_bg_queue(fc);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fc->bg_lock);
 	}
 	wake_up(&req->waitq);
 	if (req->end)
@@ -579,8 +579,8 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
  *
  * fc->connected must have been checked previously
  */
-void fuse_request_send_background_locked(struct fuse_conn *fc,
-					 struct fuse_req *req)
+void fuse_request_send_background_nocheck(struct fuse_conn *fc,
+					  struct fuse_req *req)
 {
 	BUG_ON(!test_bit(FR_BACKGROUND, &req->flags));
 	if (!test_bit(FR_WAITING, &req->flags)) {
@@ -588,6 +588,7 @@ void fuse_request_send_background_locked(struct fuse_conn *fc,
 		atomic_inc(&fc->num_waiting);
 	}
 	__set_bit(FR_ISREPLY, &req->flags);
+	spin_lock(&fc->bg_lock);
 	fc->num_background++;
 	if (fc->num_background == fc->max_background)
 		fc->blocked = 1;
@@ -597,6 +598,7 @@ void fuse_request_send_background_locked(struct fuse_conn *fc,
 	}
 	list_add_tail(&req->list, &fc->bg_queue);
 	flush_bg_queue(fc);
+	spin_unlock(&fc->bg_lock);
 }
 
 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
@@ -604,7 +606,7 @@ void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 	BUG_ON(!req->end);
 	spin_lock(&fc->lock);
 	if (fc->connected) {
-		fuse_request_send_background_locked(fc, req);
+		fuse_request_send_background_nocheck(fc, req);
 		spin_unlock(&fc->lock);
 	} else {
 		spin_unlock(&fc->lock);
@@ -2105,7 +2107,6 @@ void fuse_abort_conn(struct fuse_conn *fc, bool is_abort)
 		LIST_HEAD(to_end);
 
 		fc->connected = 0;
-		fc->blocked = 0;
 		fc->aborted = is_abort;
 		fuse_set_initialized(fc);
 		list_for_each_entry(fud, &fc->devices, entry) {
@@ -2127,8 +2128,11 @@ void fuse_abort_conn(struct fuse_conn *fc, bool is_abort)
 			list_splice_tail_init(&fpq->processing, &to_end);
 			spin_unlock(&fpq->lock);
 		}
+		spin_lock(&fc->bg_lock);
+		fc->blocked = 0;
 		fc->max_background = UINT_MAX;
 		flush_bg_queue(fc);
+		spin_unlock(&fc->bg_lock);
 
 		spin_lock(&fiq->waitq.lock);
 		fiq->connected = 0;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 32d0b883e74f..a875959dd939 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1502,7 +1502,7 @@ __acquires(fc->lock)
 
 	req->in.args[1].size = inarg->size;
 	fi->writectr++;
-	fuse_request_send_background_locked(fc, req);
+	fuse_request_send_background_nocheck(fc, req);
 	return;
 
  out_free:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f78e9614bb5f..b2c6a1cd1e2c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -500,6 +500,10 @@ struct fuse_conn {
 	/** The list of background requests set aside for later queuing */
 	struct list_head bg_queue;
 
+	/** Protects: max_background, congestion_threshold, num_background,
+	 * active_background, bg_queue, blocked */
+	spinlock_t bg_lock;
+
 	/** Flag indicating that INIT reply has been received. Allocating
 	 * any fuse request will be suspended until the flag is set */
 	int initialized;
@@ -857,8 +861,8 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args);
  */
 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 
-void fuse_request_send_background_locked(struct fuse_conn *fc,
-					 struct fuse_req *req);
+void fuse_request_send_background_nocheck(struct fuse_conn *fc,
+					  struct fuse_req *req);
 
 /* Abort all requests */
 void fuse_abort_conn(struct fuse_conn *fc, bool is_abort);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 9db8c0c745a9..a4285ec7c248 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -606,6 +606,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns)
 {
 	memset(fc, 0, sizeof(*fc));
 	spin_lock_init(&fc->lock);
+	spin_lock_init(&fc->bg_lock);
 	init_rwsem(&fc->killsb);
 	refcount_set(&fc->count, 1);
 	atomic_set(&fc->dev_count, 1);
@@ -853,6 +854,7 @@ static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 	sanitize_global_limit(&max_user_bgreq);
 	sanitize_global_limit(&max_user_congthresh);
 
+	spin_lock(&fc->bg_lock);
 	if (arg->max_background) {
 		fc->max_background = arg->max_background;
 
@@ -866,6 +868,7 @@ static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 		    fc->congestion_threshold > max_user_congthresh)
 			fc->congestion_threshold = max_user_congthresh;
 	}
+	spin_unlock(&fc->bg_lock);
 }
 
 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)

  parent reply	other threads:[~2018-08-27 19:17 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27 15:29 [PATCH 0/6] Extract bg queue logic out fuse_conn::lock Kirill Tkhai
2018-08-27 15:29 ` [PATCH 1/6] fuse: Use list_first_entry() in flush_bg_queue() Kirill Tkhai
2018-08-27 15:29 ` [PATCH 2/6] fuse: Move clear_bit() up in request_end() Kirill Tkhai
2018-08-27 15:29 ` [PATCH 3/6] fuse: Underline congestion_threshold and max_background may be read w/o fc->lock Kirill Tkhai
2018-08-27 15:29 ` [PATCH 4/6] fuse: Lock fc->lock during changing num_background and congestion_threshold Kirill Tkhai
2018-08-27 15:29 ` Kirill Tkhai [this message]
2018-08-27 15:29 ` [PATCH 6/6] fuse: Do not take fuse_conn::lock on fuse_request_send_background() Kirill Tkhai
2018-09-26 12:25   ` Miklos Szeredi
2018-09-26 15:18     ` Kirill Tkhai
2018-09-27  8:37       ` Kirill Tkhai
2018-09-27 11:25         ` Miklos Szeredi
2018-09-11 10:14 ` [PATCH 0/6] Extract bg queue logic out fuse_conn::lock Kirill Tkhai
2018-10-01  9:23   ` Miklos Szeredi

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