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 #include <linux/splice.h>
  27
  28 #include <linux/coda.h>
  29 #include "coda_psdev.h"
  30 #include "coda_linux.h"
  31 #include "coda_int.h"
  32
  33 struct coda_vm_ops {
  34         refcount_t refcnt;
  35         struct file *coda_file;
  36         const struct vm_operations_struct *host_vm_ops;
  37         struct vm_operations_struct vm_ops;
  38 };
  39
  40 static ssize_t
  41 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  42 {
  43         struct file *coda_file = iocb->ki_filp;
  44         struct inode *coda_inode = file_inode(coda_file);
  45         struct coda_file_info *cfi = coda_ftoc(coda_file);
  46         loff_t ki_pos = iocb->ki_pos;
  47         size_t count = iov_iter_count(to);
  48         ssize_t ret;
  49
  50         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  51                                   &cfi->cfi_access_intent,
  52                                   count, ki_pos, CODA_ACCESS_TYPE_READ);
  53         if (ret)
  54                 goto finish_read;
  55
  56         ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
  57
  58 finish_read:
  59         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  60                             &cfi->cfi_access_intent,
  61                             count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
  62         return ret;
  63 }
  64
  65 static ssize_t
  66 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  67 {
  68         struct file *coda_file = iocb->ki_filp;
  69         struct inode *coda_inode = file_inode(coda_file);
  70         struct coda_file_info *cfi = coda_ftoc(coda_file);
  71         struct file *host_file = cfi->cfi_container;
  72         loff_t ki_pos = iocb->ki_pos;
  73         size_t count = iov_iter_count(to);
  74         ssize_t ret;
  75
  76         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  77                                   &cfi->cfi_access_intent,
  78                                   count, ki_pos, CODA_ACCESS_TYPE_WRITE);
  79         if (ret)
  80                 goto finish_write;
  81
  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         inode_set_mtime_to_ts(coda_inode, inode_set_ctime_current(coda_inode));
  87         inode_unlock(coda_inode);
  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 ssize_t
  97 coda_file_splice_read(struct file *coda_file, loff_t *ppos,
  98                       struct pipe_inode_info *pipe,
  99                       size_t len, unsigned int flags)
 100 {
 101         struct inode *coda_inode = file_inode(coda_file);
 102         struct coda_file_info *cfi = coda_ftoc(coda_file);
 103         struct file *in = cfi->cfi_container;
 104         loff_t ki_pos = *ppos;
 105         ssize_t ret;
 106
 107         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 108                                   &cfi->cfi_access_intent,
 109                                   len, ki_pos, CODA_ACCESS_TYPE_READ);
 110         if (ret)
 111                 goto finish_read;
 112
 113         ret = vfs_splice_read(in, ppos, pipe, len, flags);
 114
 115 finish_read:
 116         venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 117                             &cfi->cfi_access_intent,
 118                             len, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
 119         return ret;
 120 }
 121
 122 static void
 123 coda_vm_open(struct vm_area_struct *vma)
 124 {
 125         struct coda_vm_ops *cvm_ops =
 126                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 127
 128         refcount_inc(&cvm_ops->refcnt);
 129
 130         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
 131                 cvm_ops->host_vm_ops->open(vma);
 132 }
 133
 134 static void
 135 coda_vm_close(struct vm_area_struct *vma)
 136 {
 137         struct coda_vm_ops *cvm_ops =
 138                 container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
 139
 140         if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
 141                 cvm_ops->host_vm_ops->close(vma);
 142
 143         if (refcount_dec_and_test(&cvm_ops->refcnt)) {
 144                 vma->vm_ops = cvm_ops->host_vm_ops;
 145                 fput(cvm_ops->coda_file);
 146                 kfree(cvm_ops);
 147         }
 148 }
 149
 150 static int
 151 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
 152 {
 153         struct inode *coda_inode = file_inode(coda_file);
 154         struct coda_file_info *cfi = coda_ftoc(coda_file);
 155         struct file *host_file = cfi->cfi_container;
 156         struct inode *host_inode = file_inode(host_file);
 157         struct coda_inode_info *cii;
 158         struct coda_vm_ops *cvm_ops;
 159         loff_t ppos;
 160         size_t count;
 161         int ret;
 162
 163         if (!host_file->f_op->mmap)
 164                 return -ENODEV;
 165
 166         if (WARN_ON(coda_file != vma->vm_file))
 167                 return -EIO;
 168
 169         count = vma->vm_end - vma->vm_start;
 170         ppos = vma->vm_pgoff * PAGE_SIZE;
 171
 172         ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
 173                                   &cfi->cfi_access_intent,
 174                                   count, ppos, CODA_ACCESS_TYPE_MMAP);
 175         if (ret)
 176                 return ret;
 177
 178         cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
 179         if (!cvm_ops)
 180                 return -ENOMEM;
 181
 182         cii = ITOC(coda_inode);
 183         spin_lock(&cii->c_lock);
 184         coda_file->f_mapping = host_file->f_mapping;
 185         if (coda_inode->i_mapping == &coda_inode->i_data)
 186                 coda_inode->i_mapping = host_inode->i_mapping;
 187
 188         /* only allow additional mmaps as long as userspace isn't changing
 189          * the container file on us! */
 190         else if (coda_inode->i_mapping != host_inode->i_mapping) {
 191                 spin_unlock(&cii->c_lock);
 192                 kfree(cvm_ops);
 193                 return -EBUSY;
 194         }
 195
 196         /* keep track of how often the coda_inode/host_file has been mmapped */
 197         cii->c_mapcount++;
 198         cfi->cfi_mapcount++;
 199         spin_unlock(&cii->c_lock);
 200
 201         vma->vm_file = get_file(host_file);
 202         ret = call_mmap(vma->vm_file, vma);
 203
 204         if (ret) {
 205                 /* if call_mmap fails, our caller will put host_file so we
 206                  * should drop the reference to the coda_file that we got.
 207                  */
 208                 fput(coda_file);
 209                 kfree(cvm_ops);
 210         } else {
 211                 /* here we add redirects for the open/close vm_operations */
 212                 cvm_ops->host_vm_ops = vma->vm_ops;
 213                 if (vma->vm_ops)
 214                         cvm_ops->vm_ops = *vma->vm_ops;
 215
 216                 cvm_ops->vm_ops.open = coda_vm_open;
 217                 cvm_ops->vm_ops.close = coda_vm_close;
 218                 cvm_ops->coda_file = coda_file;
 219                 refcount_set(&cvm_ops->refcnt, 1);
 220
 221                 vma->vm_ops = &cvm_ops->vm_ops;
 222         }
 223         return ret;
 224 }
 225
 226 int coda_open(struct inode *coda_inode, struct file *coda_file)
 227 {
 228         struct file *host_file = NULL;
 229         int error;
 230         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 231         unsigned short coda_flags = coda_flags_to_cflags(flags);
 232         struct coda_file_info *cfi;
 233
 234         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 235         if (!cfi)
 236                 return -ENOMEM;
 237
 238         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 239                            &host_file);
 240         if (!host_file)
 241                 error = -EIO;
 242
 243         if (error) {
 244                 kfree(cfi);
 245                 return error;
 246         }
 247
 248         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 249
 250         cfi->cfi_magic = CODA_MAGIC;
 251         cfi->cfi_mapcount = 0;
 252         cfi->cfi_container = host_file;
 253         /* assume access intents are supported unless we hear otherwise */
 254         cfi->cfi_access_intent = true;
 255
 256         BUG_ON(coda_file->private_data != NULL);
 257         coda_file->private_data = cfi;
 258         return 0;
 259 }
 260
 261 int coda_release(struct inode *coda_inode, struct file *coda_file)
 262 {
 263         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 264         unsigned short coda_flags = coda_flags_to_cflags(flags);
 265         struct coda_file_info *cfi;
 266         struct coda_inode_info *cii;
 267         struct inode *host_inode;
 268
 269         cfi = coda_ftoc(coda_file);
 270
 271         venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 272                           coda_flags, coda_file->f_cred->fsuid);
 273
 274         host_inode = file_inode(cfi->cfi_container);
 275         cii = ITOC(coda_inode);
 276
 277         /* did we mmap this file? */
 278         spin_lock(&cii->c_lock);
 279         if (coda_inode->i_mapping == &host_inode->i_data) {
 280                 cii->c_mapcount -= cfi->cfi_mapcount;
 281                 if (!cii->c_mapcount)
 282                         coda_inode->i_mapping = &coda_inode->i_data;
 283         }
 284         spin_unlock(&cii->c_lock);
 285
 286         fput(cfi->cfi_container);
 287         kfree(coda_file->private_data);
 288         coda_file->private_data = NULL;
 289
 290         /* VFS fput ignores the return value from file_operations->release, so
 291          * there is no use returning an error here */
 292         return 0;
 293 }
 294
 295 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 296 {
 297         struct file *host_file;
 298         struct inode *coda_inode = file_inode(coda_file);
 299         struct coda_file_info *cfi;
 300         int err;
 301
 302         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 303               S_ISLNK(coda_inode->i_mode)))
 304                 return -EINVAL;
 305
 306         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 307         if (err)
 308                 return err;
 309         inode_lock(coda_inode);
 310
 311         cfi = coda_ftoc(coda_file);
 312         host_file = cfi->cfi_container;
 313
 314         err = vfs_fsync(host_file, datasync);
 315         if (!err && !datasync)
 316                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 317         inode_unlock(coda_inode);
 318
 319         return err;
 320 }
 321
 322 const struct file_operations coda_file_operations = {
 323         .llseek         = generic_file_llseek,
 324         .read_iter      = coda_file_read_iter,
 325         .write_iter     = coda_file_write_iter,
 326         .mmap           = coda_file_mmap,
 327         .open           = coda_open,
 328         .release        = coda_release,
 329         .fsync          = coda_fsync,
 330         .splice_read    = coda_file_splice_read,
 331 };