fs/coda/file.c

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