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->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 = file_inode(coda_file);
  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->write)
  79                 return -EINVAL;
  80
  81         host_inode = file_inode(host_file);
  82         file_start_write(host_file);
  83         mutex_lock(&coda_inode->i_mutex);
  84
  85         ret = host_file->f_op->write(host_file, buf, count, ppos);
  86
  87         coda_inode->i_size = host_inode->i_size;
  88         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  89         coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
  90         mutex_unlock(&coda_inode->i_mutex);
  91         file_end_write(host_file);
  92
  93         return ret;
  94 }
  95
  96 static int
  97 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  98 {
  99         struct coda_file_info *cfi;
 100         struct coda_inode_info *cii;
 101         struct file *host_file;
 102         struct inode *coda_inode, *host_inode;
 103
 104         cfi = CODA_FTOC(coda_file);
 105         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 106         host_file = cfi->cfi_container;
 107
 108         if (!host_file->f_op->mmap)
 109                 return -ENODEV;
 110
 111         coda_inode = file_inode(coda_file);
 112         host_inode = file_inode(host_file);
 113
 114         cii = ITOC(coda_inode);
 115         spin_lock(&cii->c_lock);
 116         coda_file->f_mapping = host_file->f_mapping;
 117         if (coda_inode->i_mapping == &coda_inode->i_data)
 118                 coda_inode->i_mapping = host_inode->i_mapping;
 119
 120         /* only allow additional mmaps as long as userspace isn't changing
 121          * the container file on us! */
 122         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 123                 spin_unlock(&cii->c_lock);
 124                 return -EBUSY;
 125         }
 126
 127         /* keep track of how often the coda_inode/host_file has been mmapped */
 128         cii->c_mapcount++;
 129         cfi->cfi_mapcount++;
 130         spin_unlock(&cii->c_lock);
 131
 132         return host_file->f_op->mmap(host_file, vma);
 133 }
 134
 135 int coda_open(struct inode *coda_inode, struct file *coda_file)
 136 {
 137         struct file *host_file = NULL;
 138         int error;
 139         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 140         unsigned short coda_flags = coda_flags_to_cflags(flags);
 141         struct coda_file_info *cfi;
 142
 143         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 144         if (!cfi)
 145                 return -ENOMEM;
 146
 147         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 148                            &host_file);
 149         if (!host_file)
 150                 error = -EIO;
 151
 152         if (error) {
 153                 kfree(cfi);
 154                 return error;
 155         }
 156
 157         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 158
 159         cfi->cfi_magic = CODA_MAGIC;
 160         cfi->cfi_mapcount = 0;
 161         cfi->cfi_container = host_file;
 162
 163         BUG_ON(coda_file->private_data != NULL);
 164         coda_file->private_data = cfi;
 165         return 0;
 166 }
 167
 168 int coda_release(struct inode *coda_inode, struct file *coda_file)
 169 {
 170         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 171         unsigned short coda_flags = coda_flags_to_cflags(flags);
 172         struct coda_file_info *cfi;
 173         struct coda_inode_info *cii;
 174         struct inode *host_inode;
 175         int err;
 176
 177         cfi = CODA_FTOC(coda_file);
 178         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 179
 180         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 181                           coda_flags, coda_file->f_cred->fsuid);
 182
 183         host_inode = file_inode(cfi->cfi_container);
 184         cii = ITOC(coda_inode);
 185
 186         /* did we mmap this file? */
 187         spin_lock(&cii->c_lock);
 188         if (coda_inode->i_mapping == &host_inode->i_data) {
 189                 cii->c_mapcount -= cfi->cfi_mapcount;
 190                 if (!cii->c_mapcount)
 191                         coda_inode->i_mapping = &coda_inode->i_data;
 192         }
 193         spin_unlock(&cii->c_lock);
 194
 195         fput(cfi->cfi_container);
 196         kfree(coda_file->private_data);
 197         coda_file->private_data = NULL;
 198
 199         /* VFS fput ignores the return value from file_operations->release, so
 200          * there is no use returning an error here */
 201         return 0;
 202 }
 203
 204 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 205 {
 206         struct file *host_file;
 207         struct inode *coda_inode = file_inode(coda_file);
 208         struct coda_file_info *cfi;
 209         int err;
 210
 211         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 212               S_ISLNK(coda_inode->i_mode)))
 213                 return -EINVAL;
 214
 215         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 216         if (err)
 217                 return err;
 218         mutex_lock(&coda_inode->i_mutex);
 219
 220         cfi = CODA_FTOC(coda_file);
 221         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 222         host_file = cfi->cfi_container;
 223
 224         err = vfs_fsync(host_file, datasync);
 225         if (!err && !datasync)
 226                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 227         mutex_unlock(&coda_inode->i_mutex);
 228
 229         return err;
 230 }
 231
 232 const struct file_operations coda_file_operations = {
 233         .llseek         = generic_file_llseek,
 234         .read           = coda_file_read,
 235         .write          = coda_file_write,
 236         .mmap           = coda_file_mmap,
 237         .open           = coda_open,
 238         .release        = coda_release,
 239         .fsync          = coda_fsync,
 240         .splice_read    = coda_file_splice_read,
 241 };
 242