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
3087	decky	53	#define NAME "tmpfs"
2645	jermar	54
3087	decky	55
2645	jermar	56	vfs_info_t tmpfs_vfs_info = {
		57	.name = "tmpfs",
		58	.ops = {
		59	[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
		60	[IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
		61	[IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_DEFINED,
2731	jermar	62	[IPC_METHOD_TO_VFS_OP(VFS_TRUNCATE)] = VFS_OP_DEFINED,
2958	jermar	63	[IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
2690	jermar	64	[IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_NULL,
2742	jermar	65	[IPC_METHOD_TO_VFS_OP(VFS_DESTROY)] = VFS_OP_DEFINED,
2645	jermar	66	}
		67	};
		68
		69	fs_reg_t tmpfs_reg;
		70
		71	/**
		72	* This connection fibril processes VFS requests from VFS.
		73	*
		74	* In order to support simultaneous VFS requests, our design is as follows.
		75	* The connection fibril accepts VFS requests from VFS. If there is only one
		76	* instance of the fibril, VFS will need to serialize all VFS requests it sends
		77	* to FAT. To overcome this bottleneck, VFS can send TMPFS the
		78	* IPC_M_CONNECT_ME_TO call. In that case, a new connection fibril will be
		79	* created, which in turn will accept the call. Thus, a new phone will be
		80	* opened for VFS.
		81	*
		82	* There are few issues with this arrangement. First, VFS can run out of
		83	* available phones. In that case, VFS can close some other phones or use one
		84	* phone for more serialized requests. Similarily, TMPFS can refuse to duplicate
		85	* the connection. VFS should then just make use of already existing phones and
		86	* route its requests through them. To avoid paying the fibril creation price
		87	* upon each request, TMPFS might want to keep the connections open after the
		88	* request has been completed.
		89	*/
		90	static void tmpfs_connection(ipc_callid_t iid, ipc_call_t *icall)
		91	{
		92	if (iid) {
		93	/*
		94	* This only happens for connections opened by
		95	* IPC_M_CONNECT_ME_TO calls as opposed to callback connections
		96	* created by IPC_M_CONNECT_TO_ME.
		97	*/
		98	ipc_answer_0(iid, EOK);
		99	}
		100
		101	dprintf("VFS-TMPFS connection established.\n");
		102	while (1) {
		103	ipc_callid_t callid;
		104	ipc_call_t call;
		105
		106	callid = async_get_call(&call);
		107	switch (IPC_GET_METHOD(call)) {
2958	jermar	108	case VFS_MOUNT:
		109	tmpfs_mount(callid, &call);
		110	break;
2645	jermar	111	case VFS_LOOKUP:
		112	tmpfs_lookup(callid, &call);
		113	break;
2658	jermar	114	case VFS_READ:
		115	tmpfs_read(callid, &call);
		116	break;
2710	jermar	117	case VFS_WRITE:
		118	tmpfs_write(callid, &call);
		119	break;
2731	jermar	120	case VFS_TRUNCATE:
		121	tmpfs_truncate(callid, &call);
		122	break;
2742	jermar	123	case VFS_DESTROY:
		124	tmpfs_destroy(callid, &call);
2731	jermar	125	break;
2645	jermar	126	default:
		127	ipc_answer_0(callid, ENOTSUP);
		128	break;
		129	}
		130	}
		131	}
		132
		133	int main(int argc, char **argv)
		134	{
		135	int vfs_phone;
		136
3087	decky	137	printf(NAME ": HelenOS TMPFS file system server\n");
2645	jermar	138
		139	vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
		140	while (vfs_phone < EOK) {
		141	usleep(10000);
		142	vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
		143	}
		144
		145	int rc;
		146	rc = fs_register(vfs_phone, &tmpfs_reg, &tmpfs_vfs_info,
		147	tmpfs_connection);
		148	if (rc != EOK) {
3087	decky	149	printf(NAME ": Failed to register file system (%d)\n", rc);
2645	jermar	150	return rc;
		151	}
		152
3087	decky	153	printf(NAME ": Accepting connections\n");
2645	jermar	154	async_manager();
		155	/* not reached */
		156	return 0;
		157	}
		158
		159	/**
		160	* @}
		161	*/

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(root)/trunk/uspace/srv/fs/tmpfs/tmpfs.c/ – Rev 3087