[PATCH] FUSE - device functions

This adds the FUSE device handling functions.

This contains the following files:

 o dev.c
    - fuse device operations (read, write, release, poll)
    - registers misc device
    - support for sending requests to userspace

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 223 insertions, 0 deletions

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index eed6e89ce01..50ad6a0c39b 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -15,6 +15,12 @@
 #include <linux/backing-dev.h>
 #include <asm/semaphore.h>
 
+/** Max number of pages that can be used in a single read request */
+#define FUSE_MAX_PAGES_PER_REQ 32
+
+/** If more requests are outstanding, then the operation will block */
+#define FUSE_MAX_OUTSTANDING 10
+
 /** FUSE inode */
 struct fuse_inode {
 	/** Inode data */
@@ -28,6 +34,123 @@ struct fuse_inode {
 	unsigned long i_time;
 };
 
+/** One input argument of a request */
+struct fuse_in_arg {
+	unsigned size;
+	const void *value;
+};
+
+/** The request input */
+struct fuse_in {
+	/** The request header */
+	struct fuse_in_header h;
+
+	/** True if the data for the last argument is in req->pages */
+	unsigned argpages:1;
+
+	/** Number of arguments */
+	unsigned numargs;
+
+	/** Array of arguments */
+	struct fuse_in_arg args[3];
+};
+
+/** One output argument of a request */
+struct fuse_arg {
+	unsigned size;
+	void *value;
+};
+
+/** The request output */
+struct fuse_out {
+	/** Header returned from userspace */
+	struct fuse_out_header h;
+
+	/** Last argument is variable length (can be shorter than
+	    arg->size) */
+	unsigned argvar:1;
+
+	/** Last argument is a list of pages to copy data to */
+	unsigned argpages:1;
+
+	/** Zero partially or not copied pages */
+	unsigned page_zeroing:1;
+
+	/** Number or arguments */
+	unsigned numargs;
+
+	/** Array of arguments */
+	struct fuse_arg args[3];
+};
+
+struct fuse_req;
+struct fuse_conn;
+
+/**
+ * A request to the client
+ */
+struct fuse_req {
+	/** This can be on either unused_list, pending or processing
+	    lists in fuse_conn */
+	struct list_head list;
+
+	/** refcount */
+	atomic_t count;
+
+	/** True if the request has reply */
+	unsigned isreply:1;
+
+	/** The request is preallocated */
+	unsigned preallocated:1;
+
+	/** The request was interrupted */
+	unsigned interrupted:1;
+
+	/** Request is sent in the background */
+	unsigned background:1;
+
+	/** Data is being copied to/from the request */
+	unsigned locked:1;
+
+	/** Request has been sent to userspace */
+	unsigned sent:1;
+
+	/** The request is finished */
+	unsigned finished:1;
+
+	/** The request input */
+	struct fuse_in in;
+
+	/** The request output */
+	struct fuse_out out;
+
+	/** Used to wake up the task waiting for completion of request*/
+	wait_queue_head_t waitq;
+
+	/** Data for asynchronous requests */
+	union {
+		struct fuse_init_in_out init_in_out;
+	} misc;
+
+	/** page vector */
+	struct page *pages[FUSE_MAX_PAGES_PER_REQ];
+
+	/** number of pages in vector */
+	unsigned num_pages;
+
+	/** offset of data on first page */
+	unsigned page_offset;
+
+	/** Inode used in the request */
+	struct inode *inode;
+
+	/** Second inode used in the request (or NULL) */
+	struct inode *inode2;
+
+	/** File used in the request (or NULL) */
+	struct file *file;
+};
+
 /**
  * A Fuse connection.
  *
@@ -39,9 +162,37 @@ struct fuse_conn {
 	/** The superblock of the mounted filesystem */
 	struct super_block *sb;
 
+	/** The opened client device */
+	struct file *file;
+
 	/** The user id for this mount */
 	uid_t user_id;
 
+	/** Readers of the connection are waiting on this */
+	wait_queue_head_t waitq;
+
+	/** The list of pending requests */
+	struct list_head pending;
+
+	/** The list of requests being processed */
+	struct list_head processing;
+
+	/** Controls the maximum number of outstanding requests */
+	struct semaphore outstanding_sem;
+
+	/** This counts the number of outstanding requests if
+	    outstanding_sem would go negative */
+	unsigned outstanding_debt;
+
+	/** The list of unused requests */
+	struct list_head unused_list;
+
+	/** The next unique request id */
+	u64 reqctr;
+
+	/** Connection failed (version mismatch) */
+	unsigned conn_error : 1;
+
 	/** Backing dev info */
 	struct backing_dev_info bdi;
 };
@@ -71,13 +222,20 @@ static inline u64 get_node_id(struct inode *inode)
 	return get_fuse_inode(inode)->nodeid;
 }
 
+/** Device operations */
+extern struct file_operations fuse_dev_operations;
+
 /**
  * This is the single global spinlock which protects FUSE's structures
  *
  * The following data is protected by this lock:
  *
+ *  - the private_data field of the device file
  *  - the s_fs_info field of the super block
+ *  - unused_list, pending, processing lists in fuse_conn
+ *  - the unique request ID counter reqctr in fuse_conn
  *  - the sb (super_block) field in fuse_conn
+ *  - the file (device file) field in fuse_conn
  */
 extern spinlock_t fuse_lock;
 
@@ -87,3 +245,68 @@ extern spinlock_t fuse_lock;
  */
 void fuse_release_conn(struct fuse_conn *fc);
 
+/**
+ * Initialize the client device
+ */
+int fuse_dev_init(void);
+
+/**
+ * Cleanup the client device
+ */
+void fuse_dev_cleanup(void);
+
+/**
+ * Allocate a request
+ */
+struct fuse_req *fuse_request_alloc(void);
+
+/**
+ * Free a request
+ */
+void fuse_request_free(struct fuse_req *req);
+
+/**
+ * Reinitialize a request, the preallocated flag is left unmodified
+ */
+void fuse_reset_request(struct fuse_req *req);
+
+/**
+ * Reserve a preallocated request
+ */
+struct fuse_req *fuse_get_request(struct fuse_conn *fc);
+
+/**
+ * Reserve a preallocated request, only interruptible by SIGKILL
+ */
+struct fuse_req *fuse_get_request_nonint(struct fuse_conn *fc);
+
+/**
+ * Decrement reference count of a request.  If count goes to zero put
+ * on unused list (preallocated) or free reqest (not preallocated).
+ */
+void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request (synchronous, interruptible)
+ */
+void request_send(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request (synchronous, non-interruptible except by SIGKILL)
+ */
+void request_send_nonint(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request with no reply
+ */
+void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send a request in the background
+ */
+void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
+
+/**
+ * Send the INIT message
+ */
+void fuse_send_init(struct fuse_conn *fc);