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/pagemap.h>
  18 #include <linux/stat.h>
  19 #include <linux/cred.h>
  20 #include <linux/errno.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/string.h>
  23 #include <linux/slab.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/uio.h>
  26
  27 #include <linux/coda.h>
  28 #include "coda_psdev.h"
  29 #include "coda_linux.h"
  30 #include "coda_int.h"
  31
  32 struct coda_vm_ops {
  33         refcount_t refcnt;
  34         struct file *coda_file;
  35         const struct vm_operations_struct *host_vm_ops;
  36         struct vm_operations_struct vm_ops;
  37 };
  38
  39 static ssize_t
  40 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  41 {
  42         struct file *coda_file = iocb->ki_filp;
  43         struct inode *coda_inode = file_inode(coda_file);
  44         struct coda_file_info *cfi = coda_ftoc(coda_file);
  45         loff_t ki_pos = iocb->ki_pos;
  46         size_t count = iov_iter_count(to);
  47         ssize_t ret;
  48
  49         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  50                                   &cfi->cfi_access_intent,
  51                                   count, ki_pos, CODA_ACCESS_TYPE_READ);
  52         if (ret)
  53                 goto finish_read;
  54
  55         ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
  56
  57 finish_read:
  58         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  59                             &cfi->cfi_access_intent,
  60                             count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
  61         return ret;
  62 }
  63
  64 static ssize_t
  65 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  66 {
  67         struct file *coda_file = iocb->ki_filp;
  68         struct inode *coda_inode = file_inode(coda_file);
  69         struct coda_file_info *cfi = coda_ftoc(coda_file);
  70         struct file *host_file = cfi->cfi_container;
  71         loff_t ki_pos = iocb->ki_pos;
  72         size_t count = iov_iter_count(to);
  73         ssize_t ret;
  74
  75         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  76                                   &cfi->cfi_access_intent,
  77                                   count, ki_pos, CODA_ACCESS_TYPE_WRITE);
  78         if (ret)
  79                 goto finish_write;
  80
  81         file_start_write(host_file);
  82         inode_lock(coda_inode);
  83         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
  84         coda_inode->i_size = file_inode(host_file)->i_size;
  85         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  86         coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
  87         inode_unlock(coda_inode);
  88         file_end_write(host_file);
  89
  90 finish_write:
  91         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  92                             &cfi->cfi_access_intent,
  93                             count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);
  94         return ret;
  95 }
  96
  97 static void
  98 coda_vm_open(struct vm_area_struct *vma)
  99 {
 100         struct coda_vm_ops *cvm_ops =
 101                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 102
 103         refcount_inc(&cvm_ops->refcnt);
 104
 105         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
 106                 cvm_ops->host_vm_ops->open(vma);
 107 }
 108
 109 static void
 110 coda_vm_close(struct vm_area_struct *vma)
 111 {
 112         struct coda_vm_ops *cvm_ops =
 113                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 114
 115         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
 116                 cvm_ops->host_vm_ops->close(vma);
 117
 118         if (refcount_dec_and_test(&cvm_ops->refcnt)) {
 119                 vma->vm_ops = cvm_ops->host_vm_ops;
 120                 fput(cvm_ops->coda_file);
 121                 kfree(cvm_ops);
 122         }
 123 }
 124
 125 static int
 126 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
 127 {
 128         struct inode *coda_inode = file_inode(coda_file);
 129         struct coda_file_info *cfi = coda_ftoc(coda_file);
 130         struct file *host_file = cfi->cfi_container;
 131         struct inode *host_inode = file_inode(host_file);
 132         struct coda_inode_info *cii;
 133         struct coda_vm_ops *cvm_ops;
 134         loff_t ppos;
 135         size_t count;
 136         int ret;
 137
 138         if (!host_file->f_op->mmap)
 139                 return -ENODEV;
 140
 141         if (WARN_ON(coda_file != vma->vm_file))
 142                 return -EIO;
 143
 144         count = vma->vm_end - vma->vm_start;
 145         ppos = vma->vm_pgoff * PAGE_SIZE;
 146
 147         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 148                                   &cfi->cfi_access_intent,
 149                                   count, ppos, CODA_ACCESS_TYPE_MMAP);
 150         if (ret)
 151                 return ret;
 152
 153         cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
 154         if (!cvm_ops)
 155                 return -ENOMEM;
 156
 157         cii = ITOC(coda_inode);
 158         spin_lock(&cii->c_lock);
 159         coda_file->f_mapping = host_file->f_mapping;
 160         if (coda_inode->i_mapping == &coda_inode->i_data)
 161                 coda_inode->i_mapping = host_inode->i_mapping;
 162
 163         /* only allow additional mmaps as long as userspace isn't changing
 164          * the container file on us! */
 165         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 166                 spin_unlock(&cii->c_lock);
 167                 kfree(cvm_ops);
 168                 return -EBUSY;
 169         }
 170
 171         /* keep track of how often the coda_inode/host_file has been mmapped */
 172         cii->c_mapcount++;
 173         cfi->cfi_mapcount++;
 174         spin_unlock(&cii->c_lock);
 175
 176         vma->vm_file = get_file(host_file);
 177         ret = call_mmap(vma->vm_file, vma);
 178
 179         if (ret) {
 180                 /* if call_mmap fails, our caller will put host_file so we
 181                  * should drop the reference to the coda_file that we got.
 182                  */
 183                 fput(coda_file);
 184                 kfree(cvm_ops);
 185         } else {
 186                 /* here we add redirects for the open/close vm_operations */
 187                 cvm_ops->host_vm_ops = vma->vm_ops;
 188                 if (vma->vm_ops)
 189                         cvm_ops->vm_ops = *vma->vm_ops;
 190
 191                 cvm_ops->vm_ops.open = coda_vm_open;
 192                 cvm_ops->vm_ops.close = coda_vm_close;
 193                 cvm_ops->coda_file = coda_file;
 194                 refcount_set(&cvm_ops->refcnt, 1);
 195
 196                 vma->vm_ops = &cvm_ops->vm_ops;
 197         }
 198         return ret;
 199 }
 200
 201 int coda_open(struct inode *coda_inode, struct file *coda_file)
 202 {
 203         struct file *host_file = NULL;
 204         int error;
 205         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 206         unsigned short coda_flags = coda_flags_to_cflags(flags);
 207         struct coda_file_info *cfi;
 208
 209         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 210         if (!cfi)
 211                 return -ENOMEM;
 212
 213         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 214                            &host_file);
 215         if (!host_file)
 216                 error = -EIO;
 217
 218         if (error) {
 219                 kfree(cfi);
 220                 return error;
 221         }
 222
 223         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 224
 225         cfi->cfi_magic = CODA_MAGIC;
 226         cfi->cfi_mapcount = 0;
 227         cfi->cfi_container = host_file;
 228         /* assume access intents are supported unless we hear otherwise */
 229         cfi->cfi_access_intent = true;
 230
 231         BUG_ON(coda_file->private_data != NULL);
 232         coda_file->private_data = cfi;
 233         return 0;
 234 }
 235
 236 int coda_release(struct inode *coda_inode, struct file *coda_file)
 237 {
 238         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 239         unsigned short coda_flags = coda_flags_to_cflags(flags);
 240         struct coda_file_info *cfi;
 241         struct coda_inode_info *cii;
 242         struct inode *host_inode;
 243
 244         cfi = coda_ftoc(coda_file);
 245
 246         venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 247                           coda_flags, coda_file->f_cred->fsuid);
 248
 249         host_inode = file_inode(cfi->cfi_container);
 250         cii = ITOC(coda_inode);
 251
 252         /* did we mmap this file? */
 253         spin_lock(&cii->c_lock);
 254         if (coda_inode->i_mapping == &host_inode->i_data) {
 255                 cii->c_mapcount -= cfi->cfi_mapcount;
 256                 if (!cii->c_mapcount)
 257                         coda_inode->i_mapping = &coda_inode->i_data;
 258         }
 259         spin_unlock(&cii->c_lock);
 260
 261         fput(cfi->cfi_container);
 262         kfree(coda_file->private_data);
 263         coda_file->private_data = NULL;
 264
 265         /* VFS fput ignores the return value from file_operations->release, so
 266          * there is no use returning an error here */
 267         return 0;
 268 }
 269
 270 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 271 {
 272         struct file *host_file;
 273         struct inode *coda_inode = file_inode(coda_file);
 274         struct coda_file_info *cfi;
 275         int err;
 276
 277         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 278               S_ISLNK(coda_inode->i_mode)))
 279                 return -EINVAL;
 280
 281         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 282         if (err)
 283                 return err;
 284         inode_lock(coda_inode);
 285
 286         cfi = coda_ftoc(coda_file);
 287         host_file = cfi->cfi_container;
 288
 289         err = vfs_fsync(host_file, datasync);
 290         if (!err && !datasync)
 291                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 292         inode_unlock(coda_inode);
 293
 294         return err;
 295 }
 296
 297 const struct file_operations coda_file_operations = {
 298         .llseek         = generic_file_llseek,
 299         .read_iter      = coda_file_read_iter,
 300         .write_iter     = coda_file_write_iter,
 301         .mmap           = coda_file_mmap,
 302         .open           = coda_open,
 303         .release        = coda_release,
 304         .fsync          = coda_fsync,
 305         .splice_read    = generic_file_splice_read,
 306 };