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/refcount.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/time.h>
  15 #include <linux/file.h>
  16 #include <linux/fs.h>
  17 #include <linux/stat.h>
  18 #include <linux/cred.h>
  19 #include <linux/errno.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/string.h>
  22 #include <linux/slab.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/uio.h>
  25
  26 #include <linux/coda.h>
  27 #include "coda_psdev.h"
  28 #include "coda_linux.h"
  29 #include "coda_int.h"
  30
  31 struct coda_vm_ops {
  32         refcount_t refcnt;
  33         struct file *coda_file;
  34         const struct vm_operations_struct *host_vm_ops;
  35         struct vm_operations_struct vm_ops;
  36 };
  37
  38 static ssize_t
  39 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  40 {
  41         struct file *coda_file = iocb->ki_filp;
  42         struct inode *coda_inode = file_inode(coda_file);
  43         struct coda_file_info *cfi = coda_ftoc(coda_file);
  44         loff_t ki_pos = iocb->ki_pos;
  45         size_t count = iov_iter_count(to);
  46         ssize_t ret;
  47
  48         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  49                                   &cfi->cfi_access_intent,
  50                                   count, ki_pos, CODA_ACCESS_TYPE_READ);
  51         if (ret)
  52                 goto finish_read;
  53
  54         ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
  55
  56 finish_read:
  57         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  58                             &cfi->cfi_access_intent,
  59                             count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
  60         return ret;
  61 }
  62
  63 static ssize_t
  64 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  65 {
  66         struct file *coda_file = iocb->ki_filp;
  67         struct inode *coda_inode = file_inode(coda_file);
  68         struct coda_file_info *cfi = coda_ftoc(coda_file);
  69         struct file *host_file = cfi->cfi_container;
  70         loff_t ki_pos = iocb->ki_pos;
  71         size_t count = iov_iter_count(to);
  72         ssize_t ret;
  73
  74         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  75                                   &cfi->cfi_access_intent,
  76                                   count, ki_pos, CODA_ACCESS_TYPE_WRITE);
  77         if (ret)
  78                 goto finish_write;
  79
  80         file_start_write(host_file);
  81         inode_lock(coda_inode);
  82         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
  83         coda_inode->i_size = file_inode(host_file)->i_size;
  84         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  85         coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
  86         inode_unlock(coda_inode);
  87         file_end_write(host_file);
  88
  89 finish_write:
  90         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  91                             &cfi->cfi_access_intent,
  92                             count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);
  93         return ret;
  94 }
  95
  96 static void
  97 coda_vm_open(struct vm_area_struct *vma)
  98 {
  99         struct coda_vm_ops *cvm_ops =
 100                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 101
 102         refcount_inc(&cvm_ops->refcnt);
 103
 104         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
 105                 cvm_ops->host_vm_ops->open(vma);
 106 }
 107
 108 static void
 109 coda_vm_close(struct vm_area_struct *vma)
 110 {
 111         struct coda_vm_ops *cvm_ops =
 112                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 113
 114         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
 115                 cvm_ops->host_vm_ops->close(vma);
 116
 117         if (refcount_dec_and_test(&cvm_ops->refcnt)) {
 118                 vma->vm_ops = cvm_ops->host_vm_ops;
 119                 fput(cvm_ops->coda_file);
 120                 kfree(cvm_ops);
 121         }
 122 }
 123
 124 static int
 125 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
 126 {
 127         struct inode *coda_inode = file_inode(coda_file);
 128         struct coda_file_info *cfi = coda_ftoc(coda_file);
 129         struct file *host_file = cfi->cfi_container;
 130         struct inode *host_inode = file_inode(host_file);
 131         struct coda_inode_info *cii;
 132         struct coda_vm_ops *cvm_ops;
 133         loff_t ppos;
 134         size_t count;
 135         int ret;
 136
 137         if (!host_file->f_op->mmap)
 138                 return -ENODEV;
 139
 140         if (WARN_ON(coda_file != vma->vm_file))
 141                 return -EIO;
 142
 143         count = vma->vm_end - vma->vm_start;
 144         ppos = vma->vm_pgoff * PAGE_SIZE;
 145
 146         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 147                                   &cfi->cfi_access_intent,
 148                                   count, ppos, CODA_ACCESS_TYPE_MMAP);
 149         if (ret)
 150                 return ret;
 151
 152         cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
 153         if (!cvm_ops)
 154                 return -ENOMEM;
 155
 156         cii = ITOC(coda_inode);
 157         spin_lock(&cii->c_lock);
 158         coda_file->f_mapping = host_file->f_mapping;
 159         if (coda_inode->i_mapping == &coda_inode->i_data)
 160                 coda_inode->i_mapping = host_inode->i_mapping;
 161
 162         /* only allow additional mmaps as long as userspace isn't changing
 163          * the container file on us! */
 164         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 165                 spin_unlock(&cii->c_lock);
 166                 kfree(cvm_ops);
 167                 return -EBUSY;
 168         }
 169
 170         /* keep track of how often the coda_inode/host_file has been mmapped */
 171         cii->c_mapcount++;
 172         cfi->cfi_mapcount++;
 173         spin_unlock(&cii->c_lock);
 174
 175         vma->vm_file = get_file(host_file);
 176         ret = call_mmap(vma->vm_file, vma);
 177
 178         if (ret) {
 179                 /* if call_mmap fails, our caller will put host_file so we
 180                  * should drop the reference to the coda_file that we got.
 181                  */
 182                 fput(coda_file);
 183                 kfree(cvm_ops);
 184         } else {
 185                 /* here we add redirects for the open/close vm_operations */
 186                 cvm_ops->host_vm_ops = vma->vm_ops;
 187                 if (vma->vm_ops)
 188                         cvm_ops->vm_ops = *vma->vm_ops;
 189
 190                 cvm_ops->vm_ops.open = coda_vm_open;
 191                 cvm_ops->vm_ops.close = coda_vm_close;
 192                 cvm_ops->coda_file = coda_file;
 193                 refcount_set(&cvm_ops->refcnt, 1);
 194
 195                 vma->vm_ops = &cvm_ops->vm_ops;
 196         }
 197         return ret;
 198 }
 199
 200 int coda_open(struct inode *coda_inode, struct file *coda_file)
 201 {
 202         struct file *host_file = NULL;
 203         int error;
 204         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 205         unsigned short coda_flags = coda_flags_to_cflags(flags);
 206         struct coda_file_info *cfi;
 207
 208         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 209         if (!cfi)
 210                 return -ENOMEM;
 211
 212         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 213                            &host_file);
 214         if (!host_file)
 215                 error = -EIO;
 216
 217         if (error) {
 218                 kfree(cfi);
 219                 return error;
 220         }
 221
 222         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 223
 224         cfi->cfi_magic = CODA_MAGIC;
 225         cfi->cfi_mapcount = 0;
 226         cfi->cfi_container = host_file;
 227         /* assume access intents are supported unless we hear otherwise */
 228         cfi->cfi_access_intent = true;
 229
 230         BUG_ON(coda_file->private_data != NULL);
 231         coda_file->private_data = cfi;
 232         return 0;
 233 }
 234
 235 int coda_release(struct inode *coda_inode, struct file *coda_file)
 236 {
 237         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 238         unsigned short coda_flags = coda_flags_to_cflags(flags);
 239         struct coda_file_info *cfi;
 240         struct coda_inode_info *cii;
 241         struct inode *host_inode;
 242
 243         cfi = coda_ftoc(coda_file);
 244
 245         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 };