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file.c
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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 <[email protected]>.
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 <asm/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
30 coda_file_read(struct file *coda_file, char __user *buf, size_t count, loff_t *ppos)
31 {
32  struct coda_file_info *cfi;
33  struct file *host_file;
34 
35  cfi = CODA_FTOC(coda_file);
36  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
37  host_file = cfi->cfi_container;
38 
39  if (!host_file->f_op || !host_file->f_op->read)
40  return -EINVAL;
41 
42  return host_file->f_op->read(host_file, buf, count, ppos);
43 }
44 
45 static ssize_t
46 coda_file_splice_read(struct file *coda_file, loff_t *ppos,
47  struct pipe_inode_info *pipe, size_t count,
48  unsigned int flags)
49 {
50  ssize_t (*splice_read)(struct file *, loff_t *,
51  struct pipe_inode_info *, size_t, unsigned int);
52  struct coda_file_info *cfi;
53  struct file *host_file;
54 
55  cfi = CODA_FTOC(coda_file);
56  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
57  host_file = cfi->cfi_container;
58 
59  splice_read = host_file->f_op->splice_read;
60  if (!splice_read)
61  splice_read = default_file_splice_read;
62 
63  return splice_read(host_file, ppos, pipe, count, flags);
64 }
65 
66 static ssize_t
67 coda_file_write(struct file *coda_file, const char __user *buf, size_t count, loff_t *ppos)
68 {
69  struct inode *host_inode, *coda_inode = coda_file->f_path.dentry->d_inode;
70  struct coda_file_info *cfi;
71  struct file *host_file;
72  ssize_t ret;
73 
74  cfi = CODA_FTOC(coda_file);
75  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
76  host_file = cfi->cfi_container;
77 
78  if (!host_file->f_op || !host_file->f_op->write)
79  return -EINVAL;
80 
81  host_inode = host_file->f_path.dentry->d_inode;
82  mutex_lock(&coda_inode->i_mutex);
83 
84  ret = host_file->f_op->write(host_file, buf, count, ppos);
85 
86  coda_inode->i_size = host_inode->i_size;
87  coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
88  coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
89  mutex_unlock(&coda_inode->i_mutex);
90 
91  return ret;
92 }
93 
94 static int
95 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
96 {
97  struct coda_file_info *cfi;
98  struct coda_inode_info *cii;
99  struct file *host_file;
100  struct inode *coda_inode, *host_inode;
101 
102  cfi = CODA_FTOC(coda_file);
103  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
104  host_file = cfi->cfi_container;
105 
106  if (!host_file->f_op || !host_file->f_op->mmap)
107  return -ENODEV;
108 
109  coda_inode = coda_file->f_path.dentry->d_inode;
110  host_inode = host_file->f_path.dentry->d_inode;
111 
112  cii = ITOC(coda_inode);
113  spin_lock(&cii->c_lock);
114  coda_file->f_mapping = host_file->f_mapping;
115  if (coda_inode->i_mapping == &coda_inode->i_data)
116  coda_inode->i_mapping = host_inode->i_mapping;
117 
118  /* only allow additional mmaps as long as userspace isn't changing
119  * the container file on us! */
120  else if (coda_inode->i_mapping != host_inode->i_mapping) {
121  spin_unlock(&cii->c_lock);
122  return -EBUSY;
123  }
124 
125  /* keep track of how often the coda_inode/host_file has been mmapped */
126  cii->c_mapcount++;
127  cfi->cfi_mapcount++;
128  spin_unlock(&cii->c_lock);
129 
130  return host_file->f_op->mmap(host_file, vma);
131 }
132 
133 int coda_open(struct inode *coda_inode, struct file *coda_file)
134 {
135  struct file *host_file = NULL;
136  int error;
137  unsigned short flags = coda_file->f_flags & (~O_EXCL);
138  unsigned short coda_flags = coda_flags_to_cflags(flags);
139  struct coda_file_info *cfi;
140 
141  cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
142  if (!cfi)
143  return -ENOMEM;
144 
145  error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
146  &host_file);
147  if (!host_file)
148  error = -EIO;
149 
150  if (error) {
151  kfree(cfi);
152  return error;
153  }
154 
155  host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
156 
157  cfi->cfi_magic = CODA_MAGIC;
158  cfi->cfi_mapcount = 0;
159  cfi->cfi_container = host_file;
160 
161  BUG_ON(coda_file->private_data != NULL);
162  coda_file->private_data = cfi;
163  return 0;
164 }
165 
166 int coda_release(struct inode *coda_inode, struct file *coda_file)
167 {
168  unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
169  unsigned short coda_flags = coda_flags_to_cflags(flags);
170  struct coda_file_info *cfi;
171  struct coda_inode_info *cii;
172  struct inode *host_inode;
173  int err;
174 
175  cfi = CODA_FTOC(coda_file);
176  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
177 
178  err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
179  coda_flags, coda_file->f_cred->fsuid);
180 
181  host_inode = cfi->cfi_container->f_path.dentry->d_inode;
182  cii = ITOC(coda_inode);
183 
184  /* did we mmap this file? */
185  spin_lock(&cii->c_lock);
186  if (coda_inode->i_mapping == &host_inode->i_data) {
187  cii->c_mapcount -= cfi->cfi_mapcount;
188  if (!cii->c_mapcount)
189  coda_inode->i_mapping = &coda_inode->i_data;
190  }
191  spin_unlock(&cii->c_lock);
192 
193  fput(cfi->cfi_container);
194  kfree(coda_file->private_data);
195  coda_file->private_data = NULL;
196 
197  /* VFS fput ignores the return value from file_operations->release, so
198  * there is no use returning an error here */
199  return 0;
200 }
201 
202 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
203 {
204  struct file *host_file;
205  struct inode *coda_inode = coda_file->f_path.dentry->d_inode;
206  struct coda_file_info *cfi;
207  int err;
208 
209  if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
210  S_ISLNK(coda_inode->i_mode)))
211  return -EINVAL;
212 
213  err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
214  if (err)
215  return err;
216  mutex_lock(&coda_inode->i_mutex);
217 
218  cfi = CODA_FTOC(coda_file);
219  BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
220  host_file = cfi->cfi_container;
221 
222  err = vfs_fsync(host_file, datasync);
223  if (!err && !datasync)
224  err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
225  mutex_unlock(&coda_inode->i_mutex);
226 
227  return err;
228 }
229 
230 const struct file_operations coda_file_operations = {
231  .llseek = generic_file_llseek,
232  .read = coda_file_read,
233  .write = coda_file_write,
234  .mmap = coda_file_mmap,
235  .open = coda_open,
236  .release = coda_release,
237  .fsync = coda_fsync,
238  .splice_read = coda_file_splice_read,
239 };
240 
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