[RHEL7,COMMIT] fs/fuse kio: simplify processing and sending kio requests

Submitted by Konstantin Khorenko on May 27, 2019, 4:07 p.m.

Details

Message ID 201905271607.x4RG7Lus010425@finist-ce7.sw.ru
State New
Series "Series without cover letter"
Headers show

Commit Message

Konstantin Khorenko May 27, 2019, 4:07 p.m.
The commit is pushed to "branch-rh7-3.10.0-957.12.2.vz7.96.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-957.12.2.vz7.96.5
------>
commit fe1c6ca671c8842c9f0f7b70197cc12116caa951
Author: Pavel Butsykin <pbutsykin@virtuozzo.com>
Date:   Mon May 27 19:07:21 2019 +0300

    fs/fuse kio: simplify processing and sending kio requests
    
    This patch makes functions kpcs_req_classify() and pcs_fuse_submit() easier,
    reducing the number of cases to handle kio requests.
    
    Also, this patch allows us to get rid of the additional context switch, when
    kio request is moved to cc->work_queue list under bg_lock. After this patch,
    execution of kpcs_req_send() is available only without fc->bg_lock.
    
    Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
    Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 fs/fuse/dev.c                      | 24 ++++++-----
 fs/fuse/fuse_i.h                   |  2 +-
 fs/fuse/kio/pcs/pcs_fuse_kdirect.c | 84 +++++++++++++-------------------------
 3 files changed, 43 insertions(+), 67 deletions(-)

Patch hide | download patch | download mbox

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 3e0fecbe8db3..b8a524f04298 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -393,9 +393,11 @@  void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
 
 static void flush_bg_queue(struct fuse_conn *fc, struct fuse_iqueue *fiq)
 {
+	struct fuse_req *req, *next;
+	LIST_HEAD(kio_reqs);
+
 	while (fc->active_background < fc->max_background &&
 	       !list_empty(&fc->bg_queue)) {
-		struct fuse_req *req;
 
 		req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
 		list_del_init(&req->list);
@@ -404,16 +406,24 @@  static void flush_bg_queue(struct fuse_conn *fc, struct fuse_iqueue *fiq)
 		if (fc->kio.op) {
 			int ret = fc->kio.op->req_classify(fc, req, true, true);
 			if (likely(!ret)) {
-				fc->kio.op->req_send(fc, req, NULL, true, true);
+				list_add_tail(&req->list, &kio_reqs);
 				continue;
 			} else if (ret < 0)
 				continue;
 		}
+
 		spin_lock(&fiq->waitq.lock);
 		req->in.h.unique = fuse_get_unique(fiq);
 		queue_request(fiq, req);
 		spin_unlock(&fiq->waitq.lock);
 	}
+
+	spin_unlock(&fc->bg_lock);
+	list_for_each_entry_safe(req, next, &kio_reqs, list) {
+		list_del_init(&req->list);
+		fc->kio.op->req_send(fc, req, NULL, true);
+	}
+	spin_lock(&fc->bg_lock);
 }
 
 /*
@@ -563,7 +573,7 @@  static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req,
 	if (fc->kio.op) {
 		int ret = fc->kio.op->req_classify(fc, req, false, false);
 		if (likely(!ret))
-			return fc->kio.op->req_send(fc, req, ff, false, false);
+			return fc->kio.op->req_send(fc, req, ff, false);
 		else if (ret < 0)
 			return;
 	}
@@ -656,14 +666,6 @@  void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 {
 	WARN_ON(!req->end);
 
-	if (fc->kio.op) {
-		int ret = fc->kio.op->req_classify(fc, req, true, false);
-		if (likely(!ret))
-			return fc->kio.op->req_send(fc, req, NULL, true, false);
-		else if (ret < 0)
-			return;
-	}
-
 	if (!fuse_request_queue_background(fc, req)) {
 		if (!req->out.h.error)
 			req->out.h.error = -ENOTCONN;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7978a1d891d2..34a4317a9689 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -530,7 +530,7 @@  struct fuse_kio_ops {
 	int (*req_classify)(struct fuse_conn *fc, struct fuse_req *req, bool bg,
 			    bool locked);
 	void (*req_send)(struct fuse_conn *fc, struct fuse_req *req,
-			 struct fuse_file *ff, bool bg, bool locked);
+			 struct fuse_file *ff, bool bg);
 
 	/* Inode scope hooks */
 	int  (*file_open)(struct fuse_conn *fc, struct file *file,
diff --git a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
index a101d3950373..51e45911d6b8 100644
--- a/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
+++ b/fs/fuse/kio/pcs/pcs_fuse_kdirect.c
@@ -947,7 +947,7 @@  static int pcs_fuse_prep_rw(struct pcs_fuse_req *r, struct fuse_file *ff)
 }
 
 static void pcs_fuse_submit(struct pcs_fuse_cluster *pfc, struct fuse_req *req,
-			    struct fuse_file *ff, bool async, bool lk)
+			    struct fuse_file *ff)
 {
 	struct pcs_fuse_req *r = pcs_req_from_fuse(req);
 	struct fuse_inode *fi = get_fuse_inode(req->io_inode);
@@ -1040,11 +1040,7 @@  static void pcs_fuse_submit(struct pcs_fuse_cluster *pfc, struct fuse_req *req,
 error:
 	DTRACE("do fuse_request_end req:%p op:%d err:%d\n", req, req->in.h.opcode, req->out.h.error);
 
-	if (lk)
-		spin_unlock(&pfc->fc->bg_lock);
 	request_end(pfc->fc, req);
-	if (lk)
-		spin_lock(&pfc->fc->bg_lock);
 	return;
 
 submit:
@@ -1052,11 +1048,7 @@  static void pcs_fuse_submit(struct pcs_fuse_cluster *pfc, struct fuse_req *req,
 		req->out.h.error = -EIO;
 		goto error;
 	}
-
-	if (async)
-		pcs_cc_submit(ireq->cc, ireq);
-	else
-		ireq_process(ireq);
+	ireq_process(ireq);
 }
 
 static void kpcs_setattr_end(struct fuse_conn *fc, struct fuse_req *req)
@@ -1119,7 +1111,7 @@  static void _pcs_shrink_end(struct fuse_conn *fc, struct fuse_req *req)
 
 		TRACE("resubmit %p\n", &r->req);
 		list_del_init(&ireq->list);
-		pcs_fuse_submit(pfc, &r->req, r->req.ff, true, false);
+		pcs_fuse_submit(pfc, &r->req, r->req.ff);
 	}
 }
 
@@ -1232,64 +1224,46 @@  static int kpcs_req_classify(struct fuse_conn* fc, struct fuse_req *req,
 		return 1;
 
 	BUG_ON(!pfc);
-	/* At this point request can not belongs to any list
-	 * so we can avoid grab fc->lock here at all.
-	 */
-	BUG_ON(!list_empty(&req->list));
-
 	DTRACE("Classify req:%p op:%d end:%p bg:%d lk:%d\n", req, req->in.h.opcode,
 							  req->end, bg, lk);
 	ret = pcs_kio_classify_req(fc, req, lk);
-	if (ret) {
-		if (ret < 0) {
-			if (!bg)
-				atomic_inc(&req->count);
-			__clear_bit(FR_PENDING, &req->flags);
-			req->out.h.error = ret;
-			if (lk)
-				spin_unlock(&fc->bg_lock);
-			request_end(fc, req);
-			if (lk)
-				spin_lock(&fc->bg_lock);
-			return ret;
-		}
-		return 1;
-	}
+	if (likely(!ret))
+		return 0;
 
-	if (!lk) {
-		spin_lock(&fc->bg_lock);
-		if (fc->num_background + 1 >= fc->max_background ||
-		    !fc->connected) {
+	if (ret < 0) {
+		if (!bg)
+			atomic_inc(&req->count);
+		__clear_bit(FR_PENDING, &req->flags);
+		req->out.h.error = ret;
+		if (lk)
 			spin_unlock(&fc->bg_lock);
-			return 1;
-		}
-		fc->num_background++;
-		fc->active_background++;
-
-		if (fc->num_background == fc->congestion_threshold &&
-		    fc->bdi_initialized) {
-			set_bdi_congested(&fc->bdi, BLK_RW_SYNC);
-			set_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
-		}
-		spin_unlock(&fc->bg_lock);
+		request_end(fc, req);
+		if (lk)
+			spin_lock(&fc->bg_lock);
+		return ret;
 	}
-       return 0;
+	return 1;
 }
 
 static void kpcs_req_send(struct fuse_conn* fc, struct fuse_req *req,
-			  struct fuse_file *ff, bool bg, bool lk)
+			  struct fuse_file *ff, bool bg)
 {
-       struct pcs_fuse_cluster *pfc = (struct pcs_fuse_cluster*)fc->kio.ctx;
+	struct pcs_fuse_cluster *pfc = (struct pcs_fuse_cluster*)fc->kio.ctx;
 
-       TRACE("Send req:%p op:%d end:%p bg:%d lk:%d\n",
-               req, req->in.h.opcode, req->end, bg, lk);
+	/* At this point request can not belongs to any list
+	 * so we can avoid grab fc->lock here at all.
+	 */
+	BUG_ON(!list_empty(&req->list));
+
+	TRACE("Send req:%p op:%d end:%p bg:%d\n",
+		req, req->in.h.opcode, req->end, bg);
 
-       /* request_end below will do fuse_put_request() */
-       if (!bg)
-               atomic_inc(&req->count);
+	/* request_end below will do fuse_put_request() */
+	if (!bg)
+		atomic_inc(&req->count);
 	__clear_bit(FR_PENDING, &req->flags);
 
-	pcs_fuse_submit(pfc, req, ff ? : req->ff, lk, lk);
+	pcs_fuse_submit(pfc, req, ff ? : req->ff);
 	if (!bg)
 		wait_event(req->waitq,
 			   test_bit(FR_FINISHED, &req->flags) && !req->end);