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

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