From 0720b315976447cba3f0c3e211223b8cb82b0f93 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 10 Apr 2006 22:54:55 -0700 Subject: [PATCH] fuse: simplify locking This is in preparation for removing the global spinlock in favor of a per-mount one. The only critical part is the interaction between fuse_dev_release() and fuse_fill_super(): fuse_dev_release() must see the assignment to file->private_data, otherwise it will leak the reference to fuse_conn. This is ensured by the fput() operation, which will synchronize the assignment with other CPU's that may do a final fput() soon after this. Also redundant locking is removed from fuse_fill_super(), where exclusion is already ensured by the BKL held for this function by the VFS. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/dev.c | 31 +++++++++++-------------------- 1 file changed, 11 insertions(+), 20 deletions(-) (limited to 'fs/fuse/dev.c') diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 75c6e9166c3..c510533c684 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -23,13 +23,11 @@ static kmem_cache_t *fuse_req_cachep; static struct fuse_conn *fuse_get_conn(struct file *file) { - struct fuse_conn *fc; - spin_lock(&fuse_lock); - fc = file->private_data; - if (fc && !fc->connected) - fc = NULL; - spin_unlock(&fuse_lock); - return fc; + /* + * Lockless access is OK, because file->private data is set + * once during mount and is valid until the file is released. + */ + return file->private_data; } static void fuse_request_init(struct fuse_req *req) @@ -607,19 +605,16 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov, unsigned long nr_segs, loff_t *off) { int err; - struct fuse_conn *fc; struct fuse_req *req; struct fuse_in *in; struct fuse_copy_state cs; unsigned reqsize; + struct fuse_conn *fc = fuse_get_conn(file); + if (!fc) + return -EPERM; restart: spin_lock(&fuse_lock); - fc = file->private_data; - err = -EPERM; - if (!fc) - goto err_unlock; - err = -EAGAIN; if ((file->f_flags & O_NONBLOCK) && fc->connected && list_empty(&fc->pending)) @@ -915,17 +910,13 @@ void fuse_abort_conn(struct fuse_conn *fc) static int fuse_dev_release(struct inode *inode, struct file *file) { - struct fuse_conn *fc; - - spin_lock(&fuse_lock); - fc = file->private_data; + struct fuse_conn *fc = fuse_get_conn(file); if (fc) { + spin_lock(&fuse_lock); fc->connected = 0; end_requests(fc, &fc->pending); end_requests(fc, &fc->processing); - } - spin_unlock(&fuse_lock); - if (fc) { + spin_unlock(&fuse_lock); fasync_helper(-1, file, 0, &fc->fasync); kobject_put(&fc->kobj); } -- cgit v1.2.3