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