linux-kernel - [PATCH 3.16 280/305] fuse: cleanup fuse

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Message-ID: <lsq.1549201508.859284484@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Miklos Szeredi" <mszeredi@...hat.com>
Subject: [PATCH 3.16 280/305] fuse: cleanup fuse_file refcounting

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@...hat.com>

commit 267d84449f52349ee252db684ed95ede18e51744 upstream.

struct fuse_file is stored in file->private_data.  Make this always be a
counting reference for consistency.

This also allows fuse_sync_release() to call fuse_file_put() instead of
partially duplicating its functionality.

Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
[bwh: Backported to 3.16: force and background flags are bitfields]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/fuse/dir.c    |  2 +-
 fs/fuse/file.c   | 18 +++++++++---------
 fs/fuse/fuse_i.h |  1 -
 3 files changed, 10 insertions(+), 11 deletions(-)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -488,7 +488,7 @@ static int fuse_create_open(struct inode
 	if (err) {
 		fuse_sync_release(ff, flags);
 	} else {
-		file->private_data = fuse_file_get(ff);
+		file->private_data = ff;
 		fuse_finish_open(inode, file);
 	}
 	return err;
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -66,7 +66,7 @@ struct fuse_file *fuse_file_alloc(struct
 	}
 
 	INIT_LIST_HEAD(&ff->write_entry);
-	atomic_set(&ff->count, 0);
+	atomic_set(&ff->count, 1);
 	RB_CLEAR_NODE(&ff->polled_node);
 	init_waitqueue_head(&ff->poll_wait);
 
@@ -83,7 +83,7 @@ void fuse_file_free(struct fuse_file *ff
 	kfree(ff);
 }
 
-struct fuse_file *fuse_file_get(struct fuse_file *ff)
+static struct fuse_file *fuse_file_get(struct fuse_file *ff)
 {
 	atomic_inc(&ff->count);
 	return ff;
@@ -183,7 +183,7 @@ int fuse_do_open(struct fuse_conn *fc, u
 		ff->open_flags &= ~FOPEN_DIRECT_IO;
 
 	ff->nodeid = nodeid;
-	file->private_data = fuse_file_get(ff);
+	file->private_data = ff;
 
 	return 0;
 }
@@ -335,13 +335,13 @@ static int fuse_release(struct inode *in
 
 void fuse_sync_release(struct fuse_file *ff, int flags)
 {
-	WARN_ON(atomic_read(&ff->count) > 1);
+	WARN_ON(atomic_read(&ff->count) != 1);
 	fuse_prepare_release(ff, flags, FUSE_RELEASE);
-	ff->reserved_req->force = 1;
-	ff->reserved_req->background = 0;
-	fuse_request_send(ff->fc, ff->reserved_req);
-	fuse_put_request(ff->fc, ff->reserved_req);
-	kfree(ff);
+	/*
+	 * iput(NULL) is a no-op and since the refcount is 1 and everything's
+	 * synchronous, we are fine with not doing igrab() here"
+	 */
+	fuse_file_put(ff, true);
 }
 EXPORT_SYMBOL_GPL(fuse_sync_release);
 
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -663,7 +663,6 @@ void fuse_read_fill(struct fuse_req *req
 int fuse_open_common(struct inode *inode, struct file *file, bool isdir);
 
 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc);
-struct fuse_file *fuse_file_get(struct fuse_file *ff);
 void fuse_file_free(struct fuse_file *ff);
 void fuse_finish_open(struct inode *inode, struct file *file);