1 /*
2 * File operations for Coda.
3 * Original version: (C) 1996 Peter Braam
4 * Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
5 *
6 * Carnegie Mellon encourages users of this code to contribute improvements
7 * to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
8 */
9
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/time.h>
13 #include <linux/file.h>
14 #include <linux/fs.h>
15 #include <linux/stat.h>
16 #include <linux/cred.h>
17 #include <linux/errno.h>
18 #include <linux/spinlock.h>
19 #include <linux/string.h>
20 #include <linux/slab.h>
21 #include <linux/uaccess.h>
22
23 #include <linux/coda.h>
24 #include <linux/coda_psdev.h>
25
26 #include "coda_linux.h"
27 #include "coda_int.h"
28
29 static ssize_t
coda_file_read_iter(struct kiocb * iocb,struct iov_iter * to)30 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
31 {
32 struct file *coda_file = iocb->ki_filp;
33 struct coda_file_info *cfi = CODA_FTOC(coda_file);
34
35 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
36
37 return vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos);
38 }
39
40 static ssize_t
coda_file_splice_read(struct file * coda_file,loff_t * ppos,struct pipe_inode_info * pipe,size_t count,unsigned int flags)41 coda_file_splice_read(struct file *coda_file, loff_t *ppos,
42 struct pipe_inode_info *pipe, size_t count,
43 unsigned int flags)
44 {
45 ssize_t (*splice_read)(struct file *, loff_t *,
46 struct pipe_inode_info *, size_t, unsigned int);
47 struct coda_file_info *cfi;
48 struct file *host_file;
49
50 cfi = CODA_FTOC(coda_file);
51 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
52 host_file = cfi->cfi_container;
53
54 splice_read = host_file->f_op->splice_read;
55 if (!splice_read)
56 splice_read = default_file_splice_read;
57
58 return splice_read(host_file, ppos, pipe, count, flags);
59 }
60
61 static ssize_t
coda_file_write_iter(struct kiocb * iocb,struct iov_iter * to)62 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
63 {
64 struct file *coda_file = iocb->ki_filp;
65 struct inode *coda_inode = file_inode(coda_file);
66 struct coda_file_info *cfi = CODA_FTOC(coda_file);
67 struct file *host_file;
68 ssize_t ret;
69
70 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
71
72 host_file = cfi->cfi_container;
73 file_start_write(host_file);
74 mutex_lock(&coda_inode->i_mutex);
75 ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos);
76 coda_inode->i_size = file_inode(host_file)->i_size;
77 coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
78 coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
79 mutex_unlock(&coda_inode->i_mutex);
80 file_end_write(host_file);
81 return ret;
82 }
83
84 struct coda_vm_ops {
85 atomic_t refcnt;
86 struct file *coda_file;
87 const struct vm_operations_struct *host_vm_ops;
88 struct vm_operations_struct vm_ops;
89 };
90
91 static void
coda_vm_open(struct vm_area_struct * vma)92 coda_vm_open(struct vm_area_struct *vma)
93 {
94 struct coda_vm_ops *cvm_ops =
95 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
96
97 atomic_inc(&cvm_ops->refcnt);
98
99 if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
100 cvm_ops->host_vm_ops->open(vma);
101 }
102
103 static void
coda_vm_close(struct vm_area_struct * vma)104 coda_vm_close(struct vm_area_struct *vma)
105 {
106 struct coda_vm_ops *cvm_ops =
107 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
108
109 if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
110 cvm_ops->host_vm_ops->close(vma);
111
112 if (atomic_dec_and_test(&cvm_ops->refcnt)) {
113 vma->vm_ops = cvm_ops->host_vm_ops;
114 fput(cvm_ops->coda_file);
115 kfree(cvm_ops);
116 }
117 }
118
119 static int
coda_file_mmap(struct file * coda_file,struct vm_area_struct * vma)120 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
121 {
122 struct coda_file_info *cfi;
123 struct coda_inode_info *cii;
124 struct file *host_file;
125 struct inode *coda_inode, *host_inode;
126 struct coda_vm_ops *cvm_ops;
127 int ret;
128
129 cfi = CODA_FTOC(coda_file);
130 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
131 host_file = cfi->cfi_container;
132
133 if (!host_file->f_op->mmap)
134 return -ENODEV;
135
136 if (WARN_ON(coda_file != vma->vm_file))
137 return -EIO;
138
139 cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
140 if (!cvm_ops)
141 return -ENOMEM;
142
143 coda_inode = file_inode(coda_file);
144 host_inode = file_inode(host_file);
145
146 cii = ITOC(coda_inode);
147 spin_lock(&cii->c_lock);
148 coda_file->f_mapping = host_file->f_mapping;
149 if (coda_inode->i_mapping == &coda_inode->i_data)
150 coda_inode->i_mapping = host_inode->i_mapping;
151
152 /* only allow additional mmaps as long as userspace isn't changing
153 * the container file on us! */
154 else if (coda_inode->i_mapping != host_inode->i_mapping) {
155 spin_unlock(&cii->c_lock);
156 kfree(cvm_ops);
157 return -EBUSY;
158 }
159
160 /* keep track of how often the coda_inode/host_file has been mmapped */
161 cii->c_mapcount++;
162 cfi->cfi_mapcount++;
163 spin_unlock(&cii->c_lock);
164
165 vma->vm_file = get_file(host_file);
166 ret = host_file->f_op->mmap(host_file, vma);
167
168 if (ret) {
169 /* if call_mmap fails, our caller will put coda_file so we
170 * should drop the reference to the host_file that we got.
171 */
172 fput(host_file);
173 kfree(cvm_ops);
174 } else {
175 /* here we add redirects for the open/close vm_operations */
176 cvm_ops->host_vm_ops = vma->vm_ops;
177 if (vma->vm_ops)
178 cvm_ops->vm_ops = *vma->vm_ops;
179
180 cvm_ops->vm_ops.open = coda_vm_open;
181 cvm_ops->vm_ops.close = coda_vm_close;
182 cvm_ops->coda_file = coda_file;
183 atomic_set(&cvm_ops->refcnt, 1);
184
185 vma->vm_ops = &cvm_ops->vm_ops;
186 }
187 return ret;
188 }
189
coda_open(struct inode * coda_inode,struct file * coda_file)190 int coda_open(struct inode *coda_inode, struct file *coda_file)
191 {
192 struct file *host_file = NULL;
193 int error;
194 unsigned short flags = coda_file->f_flags & (~O_EXCL);
195 unsigned short coda_flags = coda_flags_to_cflags(flags);
196 struct coda_file_info *cfi;
197
198 cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
199 if (!cfi)
200 return -ENOMEM;
201
202 error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
203 &host_file);
204 if (!host_file)
205 error = -EIO;
206
207 if (error) {
208 kfree(cfi);
209 return error;
210 }
211
212 host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
213
214 cfi->cfi_magic = CODA_MAGIC;
215 cfi->cfi_mapcount = 0;
216 cfi->cfi_container = host_file;
217
218 BUG_ON(coda_file->private_data != NULL);
219 coda_file->private_data = cfi;
220 return 0;
221 }
222
coda_release(struct inode * coda_inode,struct file * coda_file)223 int coda_release(struct inode *coda_inode, struct file *coda_file)
224 {
225 unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
226 unsigned short coda_flags = coda_flags_to_cflags(flags);
227 struct coda_file_info *cfi;
228 struct coda_inode_info *cii;
229 struct inode *host_inode;
230 int err;
231
232 cfi = CODA_FTOC(coda_file);
233 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
234
235 err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
236 coda_flags, coda_file->f_cred->fsuid);
237
238 host_inode = file_inode(cfi->cfi_container);
239 cii = ITOC(coda_inode);
240
241 /* did we mmap this file? */
242 spin_lock(&cii->c_lock);
243 if (coda_inode->i_mapping == &host_inode->i_data) {
244 cii->c_mapcount -= cfi->cfi_mapcount;
245 if (!cii->c_mapcount)
246 coda_inode->i_mapping = &coda_inode->i_data;
247 }
248 spin_unlock(&cii->c_lock);
249
250 fput(cfi->cfi_container);
251 kfree(coda_file->private_data);
252 coda_file->private_data = NULL;
253
254 /* VFS fput ignores the return value from file_operations->release, so
255 * there is no use returning an error here */
256 return 0;
257 }
258
coda_fsync(struct file * coda_file,loff_t start,loff_t end,int datasync)259 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
260 {
261 struct file *host_file;
262 struct inode *coda_inode = file_inode(coda_file);
263 struct coda_file_info *cfi;
264 int err;
265
266 if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
267 S_ISLNK(coda_inode->i_mode)))
268 return -EINVAL;
269
270 err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
271 if (err)
272 return err;
273 mutex_lock(&coda_inode->i_mutex);
274
275 cfi = CODA_FTOC(coda_file);
276 BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
277 host_file = cfi->cfi_container;
278
279 err = vfs_fsync(host_file, datasync);
280 if (!err && !datasync)
281 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
282 mutex_unlock(&coda_inode->i_mutex);
283
284 return err;
285 }
286
287 const struct file_operations coda_file_operations = {
288 .llseek = generic_file_llseek,
289 .read_iter = coda_file_read_iter,
290 .write_iter = coda_file_write_iter,
291 .mmap = coda_file_mmap,
292 .open = coda_open,
293 .release = coda_release,
294 .fsync = coda_fsync,
295 .splice_read = coda_file_splice_read,
296 };
297
298