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
  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, 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
 224 const 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