fuse: Convert fc->attr_version into atomic64_t

This patch makes fc->attr_version of atomic64_t type, so fc->lock won't be
needed to read or modify it anymore.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dir.c

@@ -149,21 +149,6 @@ static void fuse_lookup_init(struct fuse_conn *fc, struct fuse_args *args,
 	args->out.args[0].value = outarg;
 }
 
-u64 fuse_get_attr_version(struct fuse_conn *fc)
-{
-	u64 curr_version;
-
-	/*
-	 * The spin lock isn't actually needed on 64bit archs, but we
-	 * don't yet care too much about such optimizations.
-	 */
-	spin_lock(&fc->lock);
-	curr_version = fc->attr_version;
-	spin_unlock(&fc->lock);
-
-	return curr_version;
-}
-
 /*
  * Check whether the dentry is still valid
  *
@@ -674,7 +659,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 		struct fuse_inode *fi = get_fuse_inode(inode);
 
 		spin_lock(&fc->lock);
-		fi->attr_version = ++fc->attr_version;
+		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		/*
 		 * If i_nlink == 0 then unlink doesn't make sense, yet this can
 		 * happen if userspace filesystem is careless.  It would be
@@ -828,7 +813,7 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 		struct fuse_inode *fi = get_fuse_inode(inode);
 
 		spin_lock(&fc->lock);
-		fi->attr_version = ++fc->attr_version;
+		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		inc_nlink(inode);
 		spin_unlock(&fc->lock);
 		fuse_invalidate_attr(inode);

fs/fuse/file.c

@@ -187,7 +187,7 @@ void fuse_finish_open(struct inode *inode, struct file *file)
 		struct fuse_inode *fi = get_fuse_inode(inode);
 
 		spin_lock(&fc->lock);
-		fi->attr_version = ++fc->attr_version;
+		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		i_size_write(inode, 0);
 		spin_unlock(&fc->lock);
 		fuse_invalidate_attr(inode);
@@ -608,7 +608,7 @@ static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 			struct fuse_inode *fi = get_fuse_inode(inode);
 
 			spin_lock(&fc->lock);
-			fi->attr_version = ++fc->attr_version;
+			fi->attr_version = atomic64_inc_return(&fc->attr_version);
 			spin_unlock(&fc->lock);
 		}
 
@@ -687,7 +687,7 @@ static void fuse_read_update_size(struct inode *inode, loff_t size,
 	spin_lock(&fc->lock);
 	if (attr_ver == fi->attr_version && size < inode->i_size &&
 	    !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
-		fi->attr_version = ++fc->attr_version;
+		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		i_size_write(inode, size);
 	}
 	spin_unlock(&fc->lock);
@@ -1006,7 +1006,7 @@ bool fuse_write_update_size(struct inode *inode, loff_t pos)
 	bool ret = false;
 
 	spin_lock(&fc->lock);
-	fi->attr_version = ++fc->attr_version;
+	fi->attr_version = atomic64_inc_return(&fc->attr_version);
 	if (pos > inode->i_size) {
 		i_size_write(inode, pos);
 		ret = true;

fs/fuse/fuse_i.h

@@ -730,7 +730,7 @@ struct fuse_conn {
 	struct fuse_req *destroy_req;
 
 	/** Version counter for attribute changes */
-	u64 attr_version;
+	atomic64_t attr_version;
 
 	/** Called on final put */
 	void (*release)(struct fuse_conn *);
@@ -770,6 +770,11 @@ static inline int invalid_nodeid(u64 nodeid)
 	return !nodeid || nodeid == FUSE_ROOT_ID;
 }
 
+static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
+{
+	return atomic64_read(&fc->attr_version);
+}
+
 /** Device operations */
 extern const struct file_operations fuse_dev_operations;
 
@@ -1000,8 +1005,6 @@ void fuse_flush_writepages(struct inode *inode);
 void fuse_set_nowrite(struct inode *inode);
 void fuse_release_nowrite(struct inode *inode);
 
-u64 fuse_get_attr_version(struct fuse_conn *fc);
-
 /**
  * File-system tells the kernel to invalidate cache for the given node id.
  */

fs/fuse/inode.c

@@ -163,7 +163,7 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
 
-	fi->attr_version = ++fc->attr_version;
+	fi->attr_version = atomic64_inc_return(&fc->attr_version);
 	fi->i_time = attr_valid;
 	WRITE_ONCE(fi->inval_mask, 0);
 
@@ -624,7 +624,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns)
 	fc->blocked = 0;
 	fc->initialized = 0;
 	fc->connected = 1;
-	fc->attr_version = 1;
+	atomic64_set(&fc->attr_version, 1);
 	get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 	fc->pid_ns = get_pid_ns(task_active_pid_ns(current));
 	fc->user_ns = get_user_ns(user_ns);