WebSVN – HelenOS – Blame – /trunk/uspace/srv/fs/tmpfs/tmpfs.c

Rev	Author	Line No.	Line
2645	jermar	1	/*
		2	* Copyright (c) 2006 Martin Decky
2690	jermar	3	* Copyright (c) 2008 Jakub Jermar
2645	jermar	4	* All rights reserved.
		5	*
		6	* Redistribution and use in source and binary forms, with or without
		7	* modification, are permitted provided that the following conditions
		8	* are met:
		9	*
		10	* - Redistributions of source code must retain the above copyright
		11	* notice, this list of conditions and the following disclaimer.
		12	* - Redistributions in binary form must reproduce the above copyright
		13	* notice, this list of conditions and the following disclaimer in the
		14	* documentation and/or other materials provided with the distribution.
		15	* - The name of the author may not be used to endorse or promote products
		16	* derived from this software without specific prior written permission.
		17	*
		18	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		19	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		20	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		21	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		22	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		23	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		24	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		25	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		26	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		27	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		28	*/
		29
		30	/** @addtogroup fs
		31	* @{
		32	*/
		33
		34	/**
		35	* @file tmpfs.c
		36	* @brief File system driver for in-memory file system.
		37	*
		38	* Every instance of tmpfs exists purely in memory and has neither a disk layout
		39	* nor any permanent storage (e.g. disk blocks). With each system reboot, data
		40	* stored in a tmpfs file system is lost.
		41	*/
		42
		43	#include "tmpfs.h"
		44	#include <ipc/ipc.h>
		45	#include <ipc/services.h>
		46	#include <async.h>
		47	#include <errno.h>
		48	#include <unistd.h>
		49	#include <stdio.h>
		50	#include <libfs.h>
		51	#include "../../vfs/vfs.h"
		52
		53
		54	vfs_info_t tmpfs_vfs_info = {
		55	.name = "tmpfs",
		56	.ops = {
		57	[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
		58	[IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
		59	[IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,
2731	jermar	60	[IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_DEFINED,
2958	jermar	61	[IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
2690	jermar	62	[IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,
2742	jermar	63	[IPC_METHOD_TO_VFS_OP(VFS_DESTROY)] = VFS_OP_DEFINED,
2645	jermar	64	}
		65	};
		66
		67	fs_reg_t tmpfs_reg;
		68
		69	/**
		70	* This connection fibril processes VFS requests from VFS.
		71	*
		72	* In order to support simultaneous VFS requests, our design is as follows.
		73	* The connection fibril accepts VFS requests from VFS. If there is only one
		74	* instance of the fibril, VFS will need to serialize all VFS requests it sends
		75	* to FAT. To overcome this bottleneck, VFS can send TMPFS the
		76	* IPC_M_CONNECT_ME_TO call. In that case, a new connection fibril will be
		77	* created, which in turn will accept the call. Thus, a new phone will be
		78	* opened for VFS.
		79	*
		80	* There are few issues with this arrangement. First, VFS can run out of
		81	* available phones. In that case, VFS can close some other phones or use one
		82	* phone for more serialized requests. Similarily, TMPFS can refuse to duplicate
		83	* the connection. VFS should then just make use of already existing phones and
		84	* route its requests through them. To avoid paying the fibril creation price
		85	* upon each request, TMPFS might want to keep the connections open after the
		86	* request has been completed.
		87	*/
		88	static void tmpfs_connection(ipc_callid_t iid, ipc_call_t *icall)
		89	{
		90	if (iid) {
		91	/*
		92	* This only happens for connections opened by
		93	* IPC_M_CONNECT_ME_TO calls as opposed to callback connections
		94	* created by IPC_M_CONNECT_TO_ME.
		95	*/
		96	ipc_answer_0(iid, EOK);
		97	}
		98
		99	dprintf("VFS-TMPFS connection established.\n");
		100	while (1) {
		101	ipc_callid_t callid;
		102	ipc_call_t call;
		103
		104	callid = async_get_call(&call);
		105	switch (IPC_GET_METHOD(call)) {
2958	jermar	106	case VFS_MOUNT:
		107	tmpfs_mount(callid, &call);
		108	break;
2645	jermar	109	case VFS_LOOKUP:
		110	tmpfs_lookup(callid, &call);
		111	break;
2658	jermar	112	case VFS_READ:
		113	tmpfs_read(callid, &call);
		114	break;
2710	jermar	115	case VFS_WRITE:
		116	tmpfs_write(callid, &call);
		117	break;
2731	jermar	118	case VFS_TRUNCATE:
		119	tmpfs_truncate(callid, &call);
		120	break;
2742	jermar	121	case VFS_DESTROY:
		122	tmpfs_destroy(callid, &call);
2731	jermar	123	break;
2645	jermar	124	default:
		125	ipc_answer_0(callid, ENOTSUP);
		126	break;
		127	}
		128	}
		129	}
		130
		131	int main(int argc, char **argv)
		132	{
		133	int vfs_phone;
		134
		135	printf("TMPFS: HelenOS TMPFS file system server.\n");
		136
		137	vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
		138	while (vfs_phone < EOK) {
		139	usleep(10000);
		140	vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
		141	}
		142
		143	int rc;
		144	rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,
		145	tmpfs_connection);
		146	if (rc != EOK) {
		147	printf("Failed to register the TMPFS file system (%d)\n", rc);
		148	return rc;
		149	}
		150
		151	dprintf("TMPFS filesystem registered, fs_handle=%d.\n",
		152	tmpfs_reg.fs_handle);
		153
		154	async_manager();
		155	/* not reached */
		156	return 0;
		157	}
		158
		159	/**
		160	* @}
		161	*/

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/tmpfs/tmpfs.c – Rev 2958