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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 <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_write_iter(struct kiocb * iocb,struct iov_iter * to)41 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
42 {
43 	struct file *coda_file = iocb->ki_filp;
44 	struct inode *coda_inode = file_inode(coda_file);
45 	struct coda_file_info *cfi = CODA_FTOC(coda_file);
46 	struct file *host_file;
47 	ssize_t ret;
48 
49 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
50 
51 	host_file = cfi->cfi_container;
52 	file_start_write(host_file);
53 	inode_lock(coda_inode);
54 	ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos);
55 	coda_inode->i_size = file_inode(host_file)->i_size;
56 	coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
57 	coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
58 	inode_unlock(coda_inode);
59 	file_end_write(host_file);
60 	return ret;
61 }
62 
63 static int
coda_file_mmap(struct file * coda_file,struct vm_area_struct * vma)64 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
65 {
66 	struct coda_file_info *cfi;
67 	struct coda_inode_info *cii;
68 	struct file *host_file;
69 	struct inode *coda_inode, *host_inode;
70 
71 	cfi = CODA_FTOC(coda_file);
72 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
73 	host_file = cfi->cfi_container;
74 
75 	if (!host_file->f_op->mmap)
76 		return -ENODEV;
77 
78 	coda_inode = file_inode(coda_file);
79 	host_inode = file_inode(host_file);
80 
81 	cii = ITOC(coda_inode);
82 	spin_lock(&cii->c_lock);
83 	coda_file->f_mapping = host_file->f_mapping;
84 	if (coda_inode->i_mapping == &coda_inode->i_data)
85 		coda_inode->i_mapping = host_inode->i_mapping;
86 
87 	/* only allow additional mmaps as long as userspace isn't changing
88 	 * the container file on us! */
89 	else if (coda_inode->i_mapping != host_inode->i_mapping) {
90 		spin_unlock(&cii->c_lock);
91 		return -EBUSY;
92 	}
93 
94 	/* keep track of how often the coda_inode/host_file has been mmapped */
95 	cii->c_mapcount++;
96 	cfi->cfi_mapcount++;
97 	spin_unlock(&cii->c_lock);
98 
99 	return host_file->f_op->mmap(host_file, vma);
100 }
101 
coda_open(struct inode * coda_inode,struct file * coda_file)102 int coda_open(struct inode *coda_inode, struct file *coda_file)
103 {
104 	struct file *host_file = NULL;
105 	int error;
106 	unsigned short flags = coda_file->f_flags & (~O_EXCL);
107 	unsigned short coda_flags = coda_flags_to_cflags(flags);
108 	struct coda_file_info *cfi;
109 
110 	cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
111 	if (!cfi)
112 		return -ENOMEM;
113 
114 	error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
115 			   &host_file);
116 	if (!host_file)
117 		error = -EIO;
118 
119 	if (error) {
120 		kfree(cfi);
121 		return error;
122 	}
123 
124 	host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
125 
126 	cfi->cfi_magic = CODA_MAGIC;
127 	cfi->cfi_mapcount = 0;
128 	cfi->cfi_container = host_file;
129 
130 	BUG_ON(coda_file->private_data != NULL);
131 	coda_file->private_data = cfi;
132 	return 0;
133 }
134 
coda_release(struct inode * coda_inode,struct file * coda_file)135 int coda_release(struct inode *coda_inode, struct file *coda_file)
136 {
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 	struct coda_inode_info *cii;
141 	struct inode *host_inode;
142 	int err;
143 
144 	cfi = CODA_FTOC(coda_file);
145 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
146 
147 	err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
148 			  coda_flags, coda_file->f_cred->fsuid);
149 
150 	host_inode = file_inode(cfi->cfi_container);
151 	cii = ITOC(coda_inode);
152 
153 	/* did we mmap this file? */
154 	spin_lock(&cii->c_lock);
155 	if (coda_inode->i_mapping == &host_inode->i_data) {
156 		cii->c_mapcount -= cfi->cfi_mapcount;
157 		if (!cii->c_mapcount)
158 			coda_inode->i_mapping = &coda_inode->i_data;
159 	}
160 	spin_unlock(&cii->c_lock);
161 
162 	fput(cfi->cfi_container);
163 	kfree(coda_file->private_data);
164 	coda_file->private_data = NULL;
165 
166 	/* VFS fput ignores the return value from file_operations->release, so
167 	 * there is no use returning an error here */
168 	return 0;
169 }
170 
coda_fsync(struct file * coda_file,loff_t start,loff_t end,int datasync)171 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
172 {
173 	struct file *host_file;
174 	struct inode *coda_inode = file_inode(coda_file);
175 	struct coda_file_info *cfi;
176 	int err;
177 
178 	if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
179 	      S_ISLNK(coda_inode->i_mode)))
180 		return -EINVAL;
181 
182 	err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
183 	if (err)
184 		return err;
185 	inode_lock(coda_inode);
186 
187 	cfi = CODA_FTOC(coda_file);
188 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
189 	host_file = cfi->cfi_container;
190 
191 	err = vfs_fsync(host_file, datasync);
192 	if (!err && !datasync)
193 		err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
194 	inode_unlock(coda_inode);
195 
196 	return err;
197 }
198 
199 const struct file_operations coda_file_operations = {
200 	.llseek		= generic_file_llseek,
201 	.read_iter	= coda_file_read_iter,
202 	.write_iter	= coda_file_write_iter,
203 	.mmap		= coda_file_mmap,
204 	.open		= coda_open,
205 	.release	= coda_release,
206 	.fsync		= coda_fsync,
207 	.splice_read	= generic_file_splice_read,
208 };
209 
210