[PATCH] v9fs: remove additional buffer allocation from v9fs_file_read and v9fs_file_write
[linux-2.6.git] / fs / 9p / vfs_file.c
1 /*
2  *  linux/fs/9p/vfs_file.c
3  *
4  * This file contians vfs file ops for 9P2000.
5  *
6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License as published by
11  *  the Free Software Foundation; either version 2 of the License, or
12  *  (at your option) any later version.
13  *
14  *  This program is distributed in the hope that it will be useful,
15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  *  GNU General Public License for more details.
18  *
19  *  You should have received a copy of the GNU General Public License
20  *  along with this program; if not, write to:
21  *  Free Software Foundation
22  *  51 Franklin Street, Fifth Floor
23  *  Boston, MA  02111-1301  USA
24  *
25  */
26
27 #include <linux/module.h>
28 #include <linux/errno.h>
29 #include <linux/fs.h>
30 #include <linux/file.h>
31 #include <linux/stat.h>
32 #include <linux/string.h>
33 #include <linux/smp_lock.h>
34 #include <linux/inet.h>
35 #include <linux/version.h>
36 #include <linux/list.h>
37 #include <asm/uaccess.h>
38 #include <linux/idr.h>
39
40 #include "debug.h"
41 #include "v9fs.h"
42 #include "9p.h"
43 #include "v9fs_vfs.h"
44 #include "fid.h"
45
46 /**
47  * v9fs_file_open - open a file (or directory)
48  * @inode: inode to be opened
49  * @file: file being opened
50  *
51  */
52
53 int v9fs_file_open(struct inode *inode, struct file *file)
54 {
55         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
56         struct v9fs_fid *v9fid, *fid;
57         struct v9fs_fcall *fcall = NULL;
58         int open_mode = 0;
59         unsigned int iounit = 0;
60         int newfid = -1;
61         long result = -1;
62
63         dprintk(DEBUG_VFS, "inode: %p file: %p \n", inode, file);
64
65         v9fid = v9fs_fid_get_created(file->f_dentry);
66         if (!v9fid)
67                 v9fid = v9fs_fid_lookup(file->f_dentry);
68
69         if (!v9fid) {
70                 dprintk(DEBUG_ERROR, "Couldn't resolve fid from dentry\n");
71                 return -EBADF;
72         }
73
74         if (!v9fid->fidcreate) {
75                 fid = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
76                 if (fid == NULL) {
77                         dprintk(DEBUG_ERROR, "Out of Memory\n");
78                         return -ENOMEM;
79                 }
80
81                 fid->fidopen = 0;
82                 fid->fidcreate = 0;
83                 fid->fidclunked = 0;
84                 fid->iounit = 0;
85                 fid->v9ses = v9ses;
86
87                 newfid = v9fs_get_idpool(&v9ses->fidpool);
88                 if (newfid < 0) {
89                         eprintk(KERN_WARNING, "newfid fails!\n");
90                         return -ENOSPC;
91                 }
92
93                 result =
94                     v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL, NULL);
95
96                 if (result < 0) {
97                         v9fs_put_idpool(newfid, &v9ses->fidpool);
98                         dprintk(DEBUG_ERROR, "rewalk didn't work\n");
99                         return -EBADF;
100                 }
101
102                 fid->fid = newfid;
103                 v9fid = fid;
104                 /* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */
105                 /* translate open mode appropriately */
106                 open_mode = file->f_flags & 0x3;
107
108                 if (file->f_flags & O_EXCL)
109                         open_mode |= V9FS_OEXCL;
110
111                 if (v9ses->extended) {
112                         if (file->f_flags & O_TRUNC)
113                                 open_mode |= V9FS_OTRUNC;
114
115                         if (file->f_flags & O_APPEND)
116                                 open_mode |= V9FS_OAPPEND;
117                 }
118
119                 result = v9fs_t_open(v9ses, newfid, open_mode, &fcall);
120                 if (result < 0) {
121                         dprintk(DEBUG_ERROR,
122                                 "open failed, open_mode 0x%x: %s\n", open_mode,
123                                 FCALL_ERROR(fcall));
124                         kfree(fcall);
125                         return result;
126                 }
127
128                 iounit = fcall->params.ropen.iounit;
129                 kfree(fcall);
130         } else {
131                 /* create case */
132                 newfid = v9fid->fid;
133                 iounit = v9fid->iounit;
134                 v9fid->fidcreate = 0;
135         }
136
137         file->private_data = v9fid;
138
139         v9fid->rdir_pos = 0;
140         v9fid->rdir_fcall = NULL;
141         v9fid->fidopen = 1;
142         v9fid->filp = file;
143         v9fid->iounit = iounit;
144
145         return 0;
146 }
147
148 /**
149  * v9fs_file_lock - lock a file (or directory)
150  * @inode: inode to be opened
151  * @file: file being opened
152  *
153  * XXX - this looks like a local only lock, we should extend into 9P
154  *       by using open exclusive
155  */
156
157 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
158 {
159         int res = 0;
160         struct inode *inode = filp->f_dentry->d_inode;
161
162         dprintk(DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
163
164         /* No mandatory locks */
165         if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
166                 return -ENOLCK;
167
168         if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
169                 filemap_fdatawrite(inode->i_mapping);
170                 filemap_fdatawait(inode->i_mapping);
171                 invalidate_inode_pages(&inode->i_data);
172         }
173
174         return res;
175 }
176
177 /**
178  * v9fs_file_read - read from a file
179  * @filep: file pointer to read
180  * @data: data buffer to read data into
181  * @count: size of buffer
182  * @offset: offset at which to read data
183  *
184  */
185 static ssize_t
186 v9fs_file_read(struct file *filp, char __user * data, size_t count,
187                loff_t * offset)
188 {
189         struct inode *inode = filp->f_dentry->d_inode;
190         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
191         struct v9fs_fid *v9f = filp->private_data;
192         struct v9fs_fcall *fcall = NULL;
193         int fid = v9f->fid;
194         int rsize = 0;
195         int result = 0;
196         int total = 0;
197         int n;
198
199         dprintk(DEBUG_VFS, "\n");
200
201         rsize = v9ses->maxdata - V9FS_IOHDRSZ;
202         if (v9f->iounit != 0 && rsize > v9f->iounit)
203                 rsize = v9f->iounit;
204
205         do {
206                 if (count < rsize)
207                         rsize = count;
208
209                 result = v9fs_t_read(v9ses, fid, *offset, rsize, &fcall);
210
211                 if (result < 0) {
212                         printk(KERN_ERR "9P2000: v9fs_t_read returned %d\n",
213                                result);
214
215                         kfree(fcall);
216                         return total;
217                 } else
218                         *offset += result;
219
220                 n = copy_to_user(data, fcall->params.rread.data, result);
221                 if (n) {
222                         dprintk(DEBUG_ERROR, "Problem copying to user %d\n", n);
223                         kfree(fcall);
224                         return -EFAULT;
225                 }
226
227                 count -= result;
228                 data += result;
229                 total += result;
230
231                 kfree(fcall);
232
233                 if (result < rsize)
234                         break;
235         } while (count);
236
237         return total;
238 }
239
240 /**
241  * v9fs_file_write - write to a file
242  * @filep: file pointer to write
243  * @data: data buffer to write data from
244  * @count: size of buffer
245  * @offset: offset at which to write data
246  *
247  */
248
249 static ssize_t
250 v9fs_file_write(struct file *filp, const char __user * data,
251                 size_t count, loff_t * offset)
252 {
253         struct inode *inode = filp->f_dentry->d_inode;
254         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
255         struct v9fs_fid *v9fid = filp->private_data;
256         struct v9fs_fcall *fcall;
257         int fid = v9fid->fid;
258         int result = -EIO;
259         int rsize = 0;
260         int total = 0;
261         char *buf;
262
263         dprintk(DEBUG_VFS, "data %p count %d offset %x\n", data, (int)count,
264                 (int)*offset);
265         rsize = v9ses->maxdata - V9FS_IOHDRSZ;
266         if (v9fid->iounit != 0 && rsize > v9fid->iounit)
267                 rsize = v9fid->iounit;
268
269         buf = kmalloc(v9ses->maxdata - V9FS_IOHDRSZ, GFP_KERNEL);
270         if (!buf)
271                 return -ENOMEM;
272
273         do {
274                 if (count < rsize)
275                         rsize = count;
276
277                 result = copy_from_user(buf, data, rsize);
278                 if (result) {
279                         dprintk(DEBUG_ERROR, "Problem copying from user\n");
280                         kfree(buf);
281                         return -EFAULT;
282                 }
283
284                 dump_data(buf, rsize);
285                 result = v9fs_t_write(v9ses, fid, *offset, rsize, buf, &fcall);
286                 if (result < 0) {
287                         eprintk(KERN_ERR, "error while writing: %s(%d)\n",
288                                 FCALL_ERROR(fcall), result);
289                         kfree(fcall);
290                         kfree(buf);
291                         return result;
292                 } else
293                         *offset += result;
294
295                 kfree(fcall);
296                 fcall = NULL;
297
298                 if (result != rsize) {
299                         eprintk(KERN_ERR,
300                                 "short write: v9fs_t_write returned %d\n",
301                                 result);
302                         break;
303                 }
304
305                 count -= result;
306                 data += result;
307                 total += result;
308         } while (count);
309
310         kfree(buf);
311         return total;
312 }
313
314 struct file_operations v9fs_file_operations = {
315         .llseek = generic_file_llseek,
316         .read = v9fs_file_read,
317         .write = v9fs_file_write,
318         .open = v9fs_file_open,
319         .release = v9fs_dir_release,
320         .lock = v9fs_file_lock,
321 };