summaryrefslogtreecommitdiff
path: root/fs/coda/file.c
blob: 16acc58311eab50da0c9bff3a32790f025cd7c32 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
// SPDX-License-Identifier: GPL-2.0
/*
 * File operations for Coda.
 * Original version: (C) 1996 Peter Braam 
 * Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
 *
 * Carnegie Mellon encourages users of this code to contribute improvements
 * to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
 */

#include <linux/refcount.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/cred.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/splice.h>

#include <linux/coda.h>
#include "coda_psdev.h"
#include "coda_linux.h"
#include "coda_int.h"

struct coda_vm_ops {
	refcount_t refcnt;
	struct file *coda_file;
	const struct vm_operations_struct *host_vm_ops;
	struct vm_operations_struct vm_ops;
};

static ssize_t
coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *coda_file = iocb->ki_filp;
	struct inode *coda_inode = file_inode(coda_file);
	struct coda_file_info *cfi = coda_ftoc(coda_file);
	loff_t ki_pos = iocb->ki_pos;
	size_t count = iov_iter_count(to);
	ssize_t ret;

	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
				  &cfi->cfi_access_intent,
				  count, ki_pos, CODA_ACCESS_TYPE_READ);
	if (ret)
		goto finish_read;

	ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);

finish_read:
	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
			    &cfi->cfi_access_intent,
			    count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
	return ret;
}

static ssize_t
coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *coda_file = iocb->ki_filp;
	struct inode *coda_inode = file_inode(coda_file);
	struct coda_file_info *cfi = coda_ftoc(coda_file);
	struct file *host_file = cfi->cfi_container;
	loff_t ki_pos = iocb->ki_pos;
	size_t count = iov_iter_count(to);
	ssize_t ret;

	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
				  &cfi->cfi_access_intent,
				  count, ki_pos, CODA_ACCESS_TYPE_WRITE);
	if (ret)
		goto finish_write;

	file_start_write(host_file);
	inode_lock(coda_inode);
	ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
	coda_inode->i_size = file_inode(host_file)->i_size;
	coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
	inode_set_mtime_to_ts(coda_inode, inode_set_ctime_current(coda_inode));
	inode_unlock(coda_inode);
	file_end_write(host_file);

finish_write:
	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
			    &cfi->cfi_access_intent,
			    count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);
	return ret;
}

static ssize_t
coda_file_splice_read(struct file *coda_file, loff_t *ppos,
		      struct pipe_inode_info *pipe,
		      size_t len, unsigned int flags)
{
	struct inode *coda_inode = file_inode(coda_file);
	struct coda_file_info *cfi = coda_ftoc(coda_file);
	struct file *in = cfi->cfi_container;
	loff_t ki_pos = *ppos;
	ssize_t ret;

	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
				  &cfi->cfi_access_intent,
				  len, ki_pos, CODA_ACCESS_TYPE_READ);
	if (ret)
		goto finish_read;

	ret = vfs_splice_read(in, ppos, pipe, len, flags);

finish_read:
	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
			    &cfi->cfi_access_intent,
			    len, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
	return ret;
}

static void
coda_vm_open(struct vm_area_struct *vma)
{
	struct coda_vm_ops *cvm_ops =
		container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);

	refcount_inc(&cvm_ops->refcnt);

	if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
		cvm_ops->host_vm_ops->open(vma);
}

static void
coda_vm_close(struct vm_area_struct *vma)
{
	struct coda_vm_ops *cvm_ops =
		container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);

	if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
		cvm_ops->host_vm_ops->close(vma);

	if (refcount_dec_and_test(&cvm_ops->refcnt)) {
		vma->vm_ops = cvm_ops->host_vm_ops;
		fput(cvm_ops->coda_file);
		kfree(cvm_ops);
	}
}

static int
coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
{
	struct inode *coda_inode = file_inode(coda_file);
	struct coda_file_info *cfi = coda_ftoc(coda_file);
	struct file *host_file = cfi->cfi_container;
	struct inode *host_inode = file_inode(host_file);
	struct coda_inode_info *cii;
	struct coda_vm_ops *cvm_ops;
	loff_t ppos;
	size_t count;
	int ret;

	if (!host_file->f_op->mmap)
		return -ENODEV;

	if (WARN_ON(coda_file != vma->vm_file))
		return -EIO;

	count = vma->vm_end - vma->vm_start;
	ppos = vma->vm_pgoff * PAGE_SIZE;

	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
				  &cfi->cfi_access_intent,
				  count, ppos, CODA_ACCESS_TYPE_MMAP);
	if (ret)
		return ret;

	cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
	if (!cvm_ops)
		return -ENOMEM;

	cii = ITOC(coda_inode);
	spin_lock(&cii->c_lock);
	coda_file->f_mapping = host_file->f_mapping;
	if (coda_inode->i_mapping == &coda_inode->i_data)
		coda_inode->i_mapping = host_inode->i_mapping;

	/* only allow additional mmaps as long as userspace isn't changing
	 * the container file on us! */
	else if (coda_inode->i_mapping != host_inode->i_mapping) {
		spin_unlock(&cii->c_lock);
		kfree(cvm_ops);
		return -EBUSY;
	}

	/* keep track of how often the coda_inode/host_file has been mmapped */
	cii->c_mapcount++;
	cfi->cfi_mapcount++;
	spin_unlock(&cii->c_lock);

	vma->vm_file = get_file(host_file);
	ret = call_mmap(vma->vm_file, vma);

	if (ret) {
		/* if call_mmap fails, our caller will put host_file so we
		 * should drop the reference to the coda_file that we got.
		 */
		fput(coda_file);
		kfree(cvm_ops);
	} else {
		/* here we add redirects for the open/close vm_operations */
		cvm_ops->host_vm_ops = vma->vm_ops;
		if (vma->vm_ops)
			cvm_ops->vm_ops = *vma->vm_ops;

		cvm_ops->vm_ops.open = coda_vm_open;
		cvm_ops->vm_ops.close = coda_vm_close;
		cvm_ops->coda_file = coda_file;
		refcount_set(&cvm_ops->refcnt, 1);

		vma->vm_ops = &cvm_ops->vm_ops;
	}
	return ret;
}

int coda_open(struct inode *coda_inode, struct file *coda_file)
{
	struct file *host_file = NULL;
	int error;
	unsigned short flags = coda_file->f_flags & (~O_EXCL);
	unsigned short coda_flags = coda_flags_to_cflags(flags);
	struct coda_file_info *cfi;

	cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
	if (!cfi)
		return -ENOMEM;

	error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
			   &host_file);
	if (!host_file)
		error = -EIO;

	if (error) {
		kfree(cfi);
		return error;
	}

	host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);

	cfi->cfi_magic = CODA_MAGIC;
	cfi->cfi_mapcount = 0;
	cfi->cfi_container = host_file;
	/* assume access intents are supported unless we hear otherwise */
	cfi->cfi_access_intent = true;

	BUG_ON(coda_file->private_data != NULL);
	coda_file->private_data = cfi;
	return 0;
}

int coda_release(struct inode *coda_inode, struct file *coda_file)
{
	unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
	unsigned short coda_flags = coda_flags_to_cflags(flags);
	struct coda_file_info *cfi;
	struct coda_inode_info *cii;
	struct inode *host_inode;

	cfi = coda_ftoc(coda_file);

	venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
			  coda_flags, coda_file->f_cred->fsuid);

	host_inode = file_inode(cfi->cfi_container);
	cii = ITOC(coda_inode);

	/* did we mmap this file? */
	spin_lock(&cii->c_lock);
	if (coda_inode->i_mapping == &host_inode->i_data) {
		cii->c_mapcount -= cfi->cfi_mapcount;
		if (!cii->c_mapcount)
			coda_inode->i_mapping = &coda_inode->i_data;
	}
	spin_unlock(&cii->c_lock);

	fput(cfi->cfi_container);
	kfree(coda_file->private_data);
	coda_file->private_data = NULL;

	/* VFS fput ignores the return value from file_operations->release, so
	 * there is no use returning an error here */
	return 0;
}

int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
{
	struct file *host_file;
	struct inode *coda_inode = file_inode(coda_file);
	struct coda_file_info *cfi;
	int err;

	if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
	      S_ISLNK(coda_inode->i_mode)))
		return -EINVAL;

	err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
	if (err)
		return err;
	inode_lock(coda_inode);

	cfi = coda_ftoc(coda_file);
	host_file = cfi->cfi_container;

	err = vfs_fsync(host_file, datasync);
	if (!err && !datasync)
		err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
	inode_unlock(coda_inode);

	return err;
}

const struct file_operations coda_file_operations = {
	.llseek		= generic_file_llseek,
	.read_iter	= coda_file_read_iter,
	.write_iter	= coda_file_write_iter,
	.mmap		= coda_file_mmap,
	.open		= coda_open,
	.release	= coda_release,
	.fsync		= coda_fsync,
	.splice_read	= coda_file_splice_read,
};