1/*
2 * V9FS FID Management
3 *
4 *  Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
5 *
6 *  This program is free software; you can redistribute it and/or modify
7 *  it under the terms of the GNU General Public License version 2
8 *  as published by the Free Software Foundation.
9 *
10 *  This program is distributed in the hope that it will be useful,
11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 *  GNU General Public License for more details.
14 *
15 *  You should have received a copy of the GNU General Public License
16 *  along with this program; if not, write to:
17 *  Free Software Foundation
18 *  51 Franklin Street, Fifth Floor
19 *  Boston, MA  02111-1301  USA
20 *
21 */
22
23#include <linux/module.h>
24#include <linux/errno.h>
25#include <linux/fs.h>
26#include <linux/sched.h>
27#include <linux/idr.h>
28#include <asm/semaphore.h>
29
30#include "debug.h"
31#include "v9fs.h"
32#include "9p.h"
33#include "v9fs_vfs.h"
34#include "fid.h"
35
36/**
37 * v9fs_fid_insert - add a fid to a dentry
38 * @fid: fid to add
39 * @dentry: dentry that it is being added to
40 *
41 */
42
43int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
44{
45	struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
46	dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
47		dentry->d_iname, dentry);
48	if (dentry->d_fsdata == NULL) {
49		dentry->d_fsdata =
50		    kmalloc(sizeof(struct list_head), GFP_KERNEL);
51		if (dentry->d_fsdata == NULL) {
52			dprintk(DEBUG_ERROR, "Out of memory\n");
53			return -ENOMEM;
54		}
55		fid_list = (struct list_head *)dentry->d_fsdata;
56		INIT_LIST_HEAD(fid_list);	/* Initialize list head */
57	}
58
59	fid->uid = current->uid;
60	list_add(&fid->list, fid_list);
61	return 0;
62}
63
64/**
65 * v9fs_fid_create - allocate a FID structure
66 * @dentry - dentry to link newly created fid to
67 *
68 */
69
70struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *v9ses, int fid)
71{
72	struct v9fs_fid *new;
73
74	dprintk(DEBUG_9P, "fid create fid %d\n", fid);
75	new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
76	if (new == NULL) {
77		dprintk(DEBUG_ERROR, "Out of Memory\n");
78		return ERR_PTR(-ENOMEM);
79	}
80
81	new->fid = fid;
82	new->v9ses = v9ses;
83	new->fidopen = 0;
84	new->fidclunked = 0;
85	new->iounit = 0;
86	new->rdir_pos = 0;
87	new->rdir_fcall = NULL;
88	init_MUTEX(&new->lock);
89	INIT_LIST_HEAD(&new->list);
90
91	return new;
92}
93
94/**
95 * v9fs_fid_destroy - deallocate a FID structure
96 * @fid: fid to destroy
97 *
98 */
99
100void v9fs_fid_destroy(struct v9fs_fid *fid)
101{
102	list_del(&fid->list);
103	kfree(fid);
104}
105
106/**
107 * v9fs_fid_lookup - return a locked fid from a dentry
108 * @dentry: dentry to look for fid in
109 *
110 * find a fid in the dentry, obtain its semaphore and return a reference to it.
111 * code calling lookup is responsible for releasing lock
112 *
113 * TODO: only match fids that have the same uid as current user
114 *
115 */
116
117struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
118{
119	struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
120	struct v9fs_fid *return_fid = NULL;
121
122	dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
123
124	if (fid_list)
125		return_fid = list_entry(fid_list->next, struct v9fs_fid, list);
126
127	if (!return_fid) {
128		dprintk(DEBUG_ERROR, "Couldn't find a fid in dentry\n");
129		return_fid = ERR_PTR(-EBADF);
130	}
131
132	if(down_interruptible(&return_fid->lock))
133		return ERR_PTR(-EINTR);
134
135	return return_fid;
136}
137
138/**
139 * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
140 * 			release it
141 * @dentry: dentry to look for fid in
142 *
143 * find a fid in the dentry and then clone to a new private fid
144 *
145 * TODO: only match fids that have the same uid as current user
146 *
147 */
148
149struct v9fs_fid *v9fs_fid_clone(struct dentry *dentry)
150{
151	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
152	struct v9fs_fid *base_fid, *new_fid = ERR_PTR(-EBADF);
153	struct v9fs_fcall *fcall = NULL;
154	int fid, err;
155
156	base_fid = v9fs_fid_lookup(dentry);
157
158	if(IS_ERR(base_fid))
159		return base_fid;
160
161	if(base_fid) {  /* clone fid */
162		fid = v9fs_get_idpool(&v9ses->fidpool);
163		if (fid < 0) {
164			eprintk(KERN_WARNING, "newfid fails!\n");
165			new_fid = ERR_PTR(-ENOSPC);
166			goto Release_Fid;
167		}
168
169		err = v9fs_t_walk(v9ses, base_fid->fid, fid, NULL, &fcall);
170		if (err < 0) {
171			dprintk(DEBUG_ERROR, "clone walk didn't work\n");
172			v9fs_put_idpool(fid, &v9ses->fidpool);
173			new_fid = ERR_PTR(err);
174			goto Free_Fcall;
175		}
176		new_fid = v9fs_fid_create(v9ses, fid);
177		if (new_fid == NULL) {
178			dprintk(DEBUG_ERROR, "out of memory\n");
179			new_fid = ERR_PTR(-ENOMEM);
180		}
181Free_Fcall:
182		kfree(fcall);
183	}
184
185Release_Fid:
186	up(&base_fid->lock);
187	return new_fid;
188}
189
190void v9fs_fid_clunk(struct v9fs_session_info *v9ses, struct v9fs_fid *fid)
191{
192	v9fs_t_clunk(v9ses, fid->fid);
193	v9fs_fid_destroy(fid);
194}
195