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_linux.h>
  25 #include <linux/coda_fs_i.h>
  26 #include <linux/coda_psdev.h>
  27
  28 #include "coda_int.h"
  29
  30 static ssize_t
  31 coda_file_read(struct file *coda_file, char __user *buf, size_t count, loff_t *ppos)
  32 {
  33         struct coda_file_info *cfi;
  34         struct file *host_file;
  35
  36         cfi = CODA_FTOC(coda_file);
  37         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  38         host_file = cfi->cfi_container;
  39
  40         if (!host_file->f_op || !host_file->f_op->read)
  41                 return -EINVAL;
  42
  43         return host_file->f_op->read(host_file, buf, count, ppos);
  44 }
  45
  46 static ssize_t
  47 coda_file_splice_read(struct file *coda_file, loff_t *ppos,
  48                       struct pipe_inode_info *pipe, size_t count,
  49                       unsigned int flags)
  50 {
  51         ssize_t (*splice_read)(struct file *, loff_t *,
  52                                struct pipe_inode_info *, size_t, unsigned int);
  53         struct coda_file_info *cfi;
  54         struct file *host_file;
  55
  56         cfi = CODA_FTOC(coda_file);
  57         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  58         host_file = cfi->cfi_container;
  59
  60         splice_read = host_file->f_op->splice_read;
  61         if (!splice_read)
  62                 splice_read = default_file_splice_read;
  63
  64         return splice_read(host_file, ppos, pipe, count, flags);
  65 }
  66
  67 static ssize_t
  68 coda_file_write(struct file *coda_file, const char __user *buf, size_t count, loff_t *ppos)
  69 {
  70         struct inode *host_inode, *coda_inode = coda_file->f_path.dentry->d_inode;
  71         struct coda_file_info *cfi;
  72         struct file *host_file;
  73         ssize_t ret;
  74
  75         cfi = CODA_FTOC(coda_file);
  76         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  77         host_file = cfi->cfi_container;
  78
  79         if (!host_file->f_op || !host_file->f_op->write)
  80                 return -EINVAL;
  81
  82         host_inode = host_file->f_path.dentry->d_inode;
  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
  92         return ret;
  93 }
  94
  95 static int
  96 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  97 {
  98         struct coda_file_info *cfi;
  99         struct coda_inode_info *cii;
 100         struct file *host_file;
 101         struct inode *coda_inode, *host_inode;
 102
 103         cfi = CODA_FTOC(coda_file);
 104         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 105         host_file = cfi->cfi_container;
 106
 107         if (!host_file->f_op || !host_file->f_op->mmap)
 108                 return -ENODEV;
 109
 110         coda_inode = coda_file->f_path.dentry->d_inode;
 111         host_inode = host_file->f_path.dentry->d_inode;
 112
 113         cii = ITOC(coda_inode);
 114         spin_lock(&cii->c_lock);
 115         coda_file->f_mapping = host_file->f_mapping;
 116         if (coda_inode->i_mapping == &coda_inode->i_data)
 117                 coda_inode->i_mapping = host_inode->i_mapping;
 118
 119         /* only allow additional mmaps as long as userspace isn't changing
 120          * the container file on us! */
 121         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 122                 spin_unlock(&cii->c_lock);
 123                 return -EBUSY;
 124         }
 125
 126         /* keep track of how often the coda_inode/host_file has been mmapped */
 127         cii->c_mapcount++;
 128         cfi->cfi_mapcount++;
 129         spin_unlock(&cii->c_lock);
 130
 131         return host_file->f_op->mmap(host_file, vma);
 132 }
 133
 134 int coda_open(struct inode *coda_inode, struct file *coda_file)
 135 {
 136         struct file *host_file = NULL;
 137         int error;
 138         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 139         unsigned short coda_flags = coda_flags_to_cflags(flags);
 140         struct coda_file_info *cfi;
 141
 142         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 143         if (!cfi)
 144                 return -ENOMEM;
 145
 146         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 147                            &host_file);
 148         if (!host_file)
 149                 error = -EIO;
 150
 151         if (error) {
 152                 kfree(cfi);
 153                 return error;
 154         }
 155
 156         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 157
 158         cfi->cfi_magic = CODA_MAGIC;
 159         cfi->cfi_mapcount = 0;
 160         cfi->cfi_container = host_file;
 161
 162         BUG_ON(coda_file->private_data != NULL);
 163         coda_file->private_data = cfi;
 164         return 0;
 165 }
 166
 167 int coda_release(struct inode *coda_inode, struct file *coda_file)
 168 {
 169         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 170         unsigned short coda_flags = coda_flags_to_cflags(flags);
 171         struct coda_file_info *cfi;
 172         struct coda_inode_info *cii;
 173         struct inode *host_inode;
 174         int err;
 175
 176         cfi = CODA_FTOC(coda_file);
 177         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 178
 179         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 180                           coda_flags, coda_file->f_cred->fsuid);
 181
 182         host_inode = cfi->cfi_container->f_path.dentry->d_inode;
 183         cii = ITOC(coda_inode);
 184
 185         /* did we mmap this file? */
 186         spin_lock(&cii->c_lock);
 187         if (coda_inode->i_mapping == &host_inode->i_data) {
 188                 cii->c_mapcount -= cfi->cfi_mapcount;
 189                 if (!cii->c_mapcount)
 190                         coda_inode->i_mapping = &coda_inode->i_data;
 191         }
 192         spin_unlock(&cii->c_lock);
 193
 194         fput(cfi->cfi_container);
 195         kfree(coda_file->private_data);
 196         coda_file->private_data = NULL;
 197
 198         /* VFS fput ignores the return value from file_operations->release, so
 199          * there is no use returning an error here */
 200         return 0;
 201 }
 202
 203 int coda_fsync(struct file *coda_file, int datasync)
 204 {
 205         struct file *host_file;
 206         struct inode *coda_inode = coda_file->f_path.dentry->d_inode;
 207         struct coda_file_info *cfi;
 208         int err;
 209
 210         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 211               S_ISLNK(coda_inode->i_mode)))
 212                 return -EINVAL;
 213
 214         cfi = CODA_FTOC(coda_file);
 215         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 216         host_file = cfi->cfi_container;
 217
 218         err = vfs_fsync(host_file, datasync);
 219         if (!err && !datasync)
 220                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 221
 222         return err;
 223 }
 224
 225 const struct file_operations coda_file_operations = {
 226         .llseek         = generic_file_llseek,
 227         .read           = coda_file_read,
 228         .write          = coda_file_write,
 229         .mmap           = coda_file_mmap,
 230         .open           = coda_open,
 231         .release        = coda_release,
 232         .fsync          = coda_fsync,
 233         .splice_read    = coda_file_splice_read,
 234 };
 235