linux-kernel - [PATCH 6/6] fuse: Protect fuse_file::reserved_req via corresponding fuse

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Date:   Tue, 06 Nov 2018 12:44:08 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     miklos@...redi.hu, ktkhai@...tuozzo.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] fuse: Protect fuse_file::reserved_req via corresponding
 fuse_inode::lock

This is rather natural action after previous patches,
and it just decreases load of fc->lock.

Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
---
 fs/fuse/dev.c    |   10 ++++++----
 fs/fuse/fuse_i.h |    5 ++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 3bfc5ed61c9a..cc8b95ad5b16 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -247,17 +247,18 @@ static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
 					 struct file *file)
 {
 	struct fuse_req *req = NULL;
+	struct fuse_inode *fi = get_fuse_inode(file_inode(file));
 	struct fuse_file *ff = file->private_data;
 
 	do {
 		wait_event(fc->reserved_req_waitq, ff->reserved_req);
-		spin_lock(&fc->lock);
+		spin_lock(&fi->lock);
 		if (ff->reserved_req) {
 			req = ff->reserved_req;
 			ff->reserved_req = NULL;
 			req->stolen_file = get_file(file);
 		}
-		spin_unlock(&fc->lock);
+		spin_unlock(&fi->lock);
 	} while (!req);
 
 	return req;
@@ -269,16 +270,17 @@ static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
 {
 	struct file *file = req->stolen_file;
+	struct fuse_inode *fi = get_fuse_inode(file_inode(file));
 	struct fuse_file *ff = file->private_data;
 
 	WARN_ON(req->max_pages);
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	memset(req, 0, sizeof(*req));
 	fuse_request_init(req, NULL, NULL, 0);
 	BUG_ON(ff->reserved_req);
 	ff->reserved_req = req;
 	wake_up_all(&fc->reserved_req_waitq);
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 	fput(file);
 }
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f7442bcecbb0..10b20a24f693 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -166,7 +166,10 @@ struct fuse_file {
 	/** Fuse connection for this file */
 	struct fuse_conn *fc;
 
-	/** Request reserved for flush and release */
+	/*
+	 * Request reserved for flush and release.
+	 * Modified under relative fuse_inode::lock.
+	 */
 	struct fuse_req *reserved_req;
 
 	/** Kernel file handle guaranteed to be unique */