fs/coda/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * File operations for Coda.
   4  * Original version: (C) 1996 Peter Braam
   5  * Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
   6  *
   7  * Carnegie Mellon encourages users of this code to contribute improvements
   8  * to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/kernel.h>
  13 #include <linux/time.h>
  14 #include <linux/file.h>
  15 #include <linux/fs.h>
  16 #include <linux/stat.h>
  17 #include <linux/cred.h>
  18 #include <linux/errno.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/string.h>
  21 #include <linux/slab.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/uio.h>
  24
  25 #include <linux/coda.h>
  26 #include "coda_psdev.h"
  27 #include "coda_linux.h"
  28 #include "coda_int.h"
  29
  30 struct coda_vm_ops {
  31         atomic_t refcnt;
  32         struct file *coda_file;
  33         const struct vm_operations_struct *host_vm_ops;
  34         struct vm_operations_struct vm_ops;
  35 };
  36
  37 static ssize_t
  38 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  39 {
  40         struct file *coda_file = iocb->ki_filp;
  41         struct inode *coda_inode = file_inode(coda_file);
  42         struct coda_file_info *cfi = coda_ftoc(coda_file);
  43         loff_t ki_pos = iocb->ki_pos;
  44         size_t count = iov_iter_count(to);
  45         ssize_t ret;
  46
  47         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  48                                   &cfi->cfi_access_intent,
  49                                   count, ki_pos, CODA_ACCESS_TYPE_READ);
  50         if (ret)
  51                 goto finish_read;
  52
  53         ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
  54
  55 finish_read:
  56         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  57                             &cfi->cfi_access_intent,
  58                             count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
  59         return ret;
  60 }
  61
  62 static ssize_t
  63 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  64 {
  65         struct file *coda_file = iocb->ki_filp;
  66         struct inode *coda_inode = file_inode(coda_file);
  67         struct coda_file_info *cfi = coda_ftoc(coda_file);
  68         struct file *host_file = cfi->cfi_container;
  69         loff_t ki_pos = iocb->ki_pos;
  70         size_t count = iov_iter_count(to);
  71         ssize_t ret;
  72
  73         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  74                                   &cfi->cfi_access_intent,
  75                                   count, ki_pos, CODA_ACCESS_TYPE_WRITE);
  76         if (ret)
  77                 goto finish_write;
  78
  79         file_start_write(host_file);
  80         inode_lock(coda_inode);
  81         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
  82         coda_inode->i_size = file_inode(host_file)->i_size;
  83         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  84         coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
  85         inode_unlock(coda_inode);
  86         file_end_write(host_file);
  87
  88 finish_write:
  89         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  90                             &cfi->cfi_access_intent,
  91                             count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);
  92         return ret;
  93 }
  94
  95 static void
  96 coda_vm_open(struct vm_area_struct *vma)
  97 {
  98         struct coda_vm_ops *cvm_ops =
  99                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 100
 101         atomic_inc(&cvm_ops->refcnt);
 102
 103         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
 104                 cvm_ops->host_vm_ops->open(vma);
 105 }
 106
 107 static void
 108 coda_vm_close(struct vm_area_struct *vma)
 109 {
 110         struct coda_vm_ops *cvm_ops =
 111                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 112
 113         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
 114                 cvm_ops->host_vm_ops->close(vma);
 115
 116         if (atomic_dec_and_test(&cvm_ops->refcnt)) {
 117                 vma->vm_ops = cvm_ops->host_vm_ops;
 118                 fput(cvm_ops->coda_file);
 119                 kfree(cvm_ops);
 120         }
 121 }
 122
 123 static int
 124 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
 125 {
 126         struct inode *coda_inode = file_inode(coda_file);
 127         struct coda_file_info *cfi = coda_ftoc(coda_file);
 128         struct file *host_file = cfi->cfi_container;
 129         struct inode *host_inode = file_inode(host_file);
 130         struct coda_inode_info *cii;
 131         struct coda_vm_ops *cvm_ops;
 132         loff_t ppos;
 133         size_t count;
 134         int ret;
 135
 136         if (!host_file->f_op->mmap)
 137                 return -ENODEV;
 138
 139         if (WARN_ON(coda_file != vma->vm_file))
 140                 return -EIO;
 141
 142         count = vma->vm_end - vma->vm_start;
 143         ppos = vma->vm_pgoff * PAGE_SIZE;
 144
 145         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 146                                   &cfi->cfi_access_intent,
 147                                   count, ppos, CODA_ACCESS_TYPE_MMAP);
 148         if (ret)
 149                 return ret;
 150
 151         cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
 152         if (!cvm_ops)
 153                 return -ENOMEM;
 154
 155         cii = ITOC(coda_inode);
 156         spin_lock(&cii->c_lock);
 157         coda_file->f_mapping = host_file->f_mapping;
 158         if (coda_inode->i_mapping == &coda_inode->i_data)
 159                 coda_inode->i_mapping = host_inode->i_mapping;
 160
 161         /* only allow additional mmaps as long as userspace isn't changing
 162          * the container file on us! */
 163         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 164                 spin_unlock(&cii->c_lock);
 165                 kfree(cvm_ops);
 166                 return -EBUSY;
 167         }
 168
 169         /* keep track of how often the coda_inode/host_file has been mmapped */
 170         cii->c_mapcount++;
 171         cfi->cfi_mapcount++;
 172         spin_unlock(&cii->c_lock);
 173
 174         vma->vm_file = get_file(host_file);
 175         ret = call_mmap(vma->vm_file, vma);
 176
 177         if (ret) {
 178                 /* if call_mmap fails, our caller will put host_file so we
 179                  * should drop the reference to the coda_file that we got.
 180                  */
 181                 fput(coda_file);
 182                 kfree(cvm_ops);
 183         } else {
 184                 /* here we add redirects for the open/close vm_operations */
 185                 cvm_ops->host_vm_ops = vma->vm_ops;
 186                 if (vma->vm_ops)
 187                         cvm_ops->vm_ops = *vma->vm_ops;
 188
 189                 cvm_ops->vm_ops.open = coda_vm_open;
 190                 cvm_ops->vm_ops.close = coda_vm_close;
 191                 cvm_ops->coda_file = coda_file;
 192                 atomic_set(&cvm_ops->refcnt, 1);
 193
 194                 vma->vm_ops = &cvm_ops->vm_ops;
 195         }
 196         return ret;
 197 }
 198
 199 int coda_open(struct inode *coda_inode, struct file *coda_file)
 200 {
 201         struct file *host_file = NULL;
 202         int error;
 203         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 204         unsigned short coda_flags = coda_flags_to_cflags(flags);
 205         struct coda_file_info *cfi;
 206
 207         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 208         if (!cfi)
 209                 return -ENOMEM;
 210
 211         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 212                            &host_file);
 213         if (!host_file)
 214                 error = -EIO;
 215
 216         if (error) {
 217                 kfree(cfi);
 218                 return error;
 219         }
 220
 221         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 222
 223         cfi->cfi_magic = CODA_MAGIC;
 224         cfi->cfi_mapcount = 0;
 225         cfi->cfi_container = host_file;
 226         /* assume access intents are supported unless we hear otherwise */
 227         cfi->cfi_access_intent = true;
 228
 229         BUG_ON(coda_file->private_data != NULL);
 230         coda_file->private_data = cfi;
 231         return 0;
 232 }
 233
 234 int coda_release(struct inode *coda_inode, struct file *coda_file)
 235 {
 236         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 237         unsigned short coda_flags = coda_flags_to_cflags(flags);
 238         struct coda_file_info *cfi;
 239         struct coda_inode_info *cii;
 240         struct inode *host_inode;
 241         int err;
 242
 243         cfi = coda_ftoc(coda_file);
 244
 245         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 246                           coda_flags, coda_file->f_cred->fsuid);
 247
 248         host_inode = file_inode(cfi->cfi_container);
 249         cii = ITOC(coda_inode);
 250
 251         /* did we mmap this file? */
 252         spin_lock(&cii->c_lock);
 253         if (coda_inode->i_mapping == &host_inode->i_data) {
 254                 cii->c_mapcount -= cfi->cfi_mapcount;
 255                 if (!cii->c_mapcount)
 256                         coda_inode->i_mapping = &coda_inode->i_data;
 257         }
 258         spin_unlock(&cii->c_lock);
 259
 260         fput(cfi->cfi_container);
 261         kfree(coda_file->private_data);
 262         coda_file->private_data = NULL;
 263
 264         /* VFS fput ignores the return value from file_operations->release, so
 265          * there is no use returning an error here */
 266         return 0;
 267 }
 268
 269 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 270 {
 271         struct file *host_file;
 272         struct inode *coda_inode = file_inode(coda_file);
 273         struct coda_file_info *cfi;
 274         int err;
 275
 276         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 277               S_ISLNK(coda_inode->i_mode)))
 278                 return -EINVAL;
 279
 280         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 281         if (err)
 282                 return err;
 283         inode_lock(coda_inode);
 284
 285         cfi = coda_ftoc(coda_file);
 286         host_file = cfi->cfi_container;
 287
 288         err = vfs_fsync(host_file, datasync);
 289         if (!err && !datasync)
 290                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 291         inode_unlock(coda_inode);
 292
 293         return err;
 294 }
 295
 296 const struct file_operations coda_file_operations = {
 297         .llseek         = generic_file_llseek,
 298         .read_iter      = coda_file_read_iter,
 299         .write_iter     = coda_file_write_iter,
 300         .mmap           = coda_file_mmap,
 301         .open           = coda_open,
 302         .release        = coda_release,
 303         .fsync          = coda_fsync,
 304         .splice_read    = generic_file_splice_read,
 305 };