Root/fs/coda/file.c

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 <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
29static ssize_t
30coda_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
45static ssize_t
46coda_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
66static ssize_t
67coda_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
94static int
95coda_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
133int 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
166int 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
202int coda_fsync(struct file *coda_file, 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    cfi = CODA_FTOC(coda_file);
214    BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
215    host_file = cfi->cfi_container;
216
217    err = vfs_fsync(host_file, datasync);
218    if (!err && !datasync)
219        err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
220
221    return err;
222}
223
224const struct file_operations coda_file_operations = {
225    .llseek = generic_file_llseek,
226    .read = coda_file_read,
227    .write = coda_file_write,
228    .mmap = coda_file_mmap,
229    .open = coda_open,
230    .release = coda_release,
231    .fsync = coda_fsync,
232    .splice_read = coda_file_splice_read,
233};
234
235

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