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 static ssize_t
  31 coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
  32 {
  33         struct file *coda_file = iocb->ki_filp;
  34         struct coda_file_info *cfi = CODA_FTOC(coda_file);
  35
  36         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  37
  38         return vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
  39 }
  40
  41 static ssize_t
  42 coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
  43 {
  44         struct file *coda_file = iocb->ki_filp;
  45         struct inode *coda_inode = file_inode(coda_file);
  46         struct coda_file_info *cfi = CODA_FTOC(coda_file);
  47         struct file *host_file;
  48         ssize_t ret;
  49
  50         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  51
  52         host_file = cfi->cfi_container;
  53         file_start_write(host_file);
  54         inode_lock(coda_inode);
  55         ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
  56         coda_inode->i_size = file_inode(host_file)->i_size;
  57         coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
  58         coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);
  59         inode_unlock(coda_inode);
  60         file_end_write(host_file);
  61         return ret;
  62 }
  63
  64 static int
  65 coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  66 {
  67         struct coda_file_info *cfi;
  68         struct coda_inode_info *cii;
  69         struct file *host_file;
  70         struct inode *coda_inode, *host_inode;
  71
  72         cfi = CODA_FTOC(coda_file);
  73         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  74         host_file = cfi->cfi_container;
  75
  76         if (!host_file->f_op->mmap)
  77                 return -ENODEV;
  78
  79         coda_inode = file_inode(coda_file);
  80         host_inode = file_inode(host_file);
  81
  82         cii = ITOC(coda_inode);
  83         spin_lock(&cii->c_lock);
  84         coda_file->f_mapping = host_file->f_mapping;
  85         if (coda_inode->i_mapping == &coda_inode->i_data)
  86                 coda_inode->i_mapping = host_inode->i_mapping;
  87
  88         /* only allow additional mmaps as long as userspace isn't changing
  89          * the container file on us! */
  90         else if (coda_inode->i_mapping != host_inode->i_mapping) {
  91                 spin_unlock(&cii->c_lock);
  92                 return -EBUSY;
  93         }
  94
  95         /* keep track of how often the coda_inode/host_file has been mmapped */
  96         cii->c_mapcount++;
  97         cfi->cfi_mapcount++;
  98         spin_unlock(&cii->c_lock);
  99
 100         return call_mmap(host_file, vma);
 101 }
 102
 103 int coda_open(struct inode *coda_inode, struct file *coda_file)
 104 {
 105         struct file *host_file = NULL;
 106         int error;
 107         unsigned short flags = coda_file->f_flags & (~O_EXCL);
 108         unsigned short coda_flags = coda_flags_to_cflags(flags);
 109         struct coda_file_info *cfi;
 110
 111         cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 112         if (!cfi)
 113                 return -ENOMEM;
 114
 115         error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 116                            &host_file);
 117         if (!host_file)
 118                 error = -EIO;
 119
 120         if (error) {
 121                 kfree(cfi);
 122                 return error;
 123         }
 124
 125         host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 126
 127         cfi->cfi_magic = CODA_MAGIC;
 128         cfi->cfi_mapcount = 0;
 129         cfi->cfi_container = host_file;
 130
 131         BUG_ON(coda_file->private_data != NULL);
 132         coda_file->private_data = cfi;
 133         return 0;
 134 }
 135
 136 int coda_release(struct inode *coda_inode, struct file *coda_file)
 137 {
 138         unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 139         unsigned short coda_flags = coda_flags_to_cflags(flags);
 140         struct coda_file_info *cfi;
 141         struct coda_inode_info *cii;
 142         struct inode *host_inode;
 143         int err;
 144
 145         cfi = CODA_FTOC(coda_file);
 146         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 147
 148         err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 149                           coda_flags, coda_file->f_cred->fsuid);
 150
 151         host_inode = file_inode(cfi->cfi_container);
 152         cii = ITOC(coda_inode);
 153
 154         /* did we mmap this file? */
 155         spin_lock(&cii->c_lock);
 156         if (coda_inode->i_mapping == &host_inode->i_data) {
 157                 cii->c_mapcount -= cfi->cfi_mapcount;
 158                 if (!cii->c_mapcount)
 159                         coda_inode->i_mapping = &coda_inode->i_data;
 160         }
 161         spin_unlock(&cii->c_lock);
 162
 163         fput(cfi->cfi_container);
 164         kfree(coda_file->private_data);
 165         coda_file->private_data = NULL;
 166
 167         /* VFS fput ignores the return value from file_operations->release, so
 168          * there is no use returning an error here */
 169         return 0;
 170 }
 171
 172 int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 173 {
 174         struct file *host_file;
 175         struct inode *coda_inode = file_inode(coda_file);
 176         struct coda_file_info *cfi;
 177         int err;
 178
 179         if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 180               S_ISLNK(coda_inode->i_mode)))
 181                 return -EINVAL;
 182
 183         err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 184         if (err)
 185                 return err;
 186         inode_lock(coda_inode);
 187
 188         cfi = CODA_FTOC(coda_file);
 189         BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 190         host_file = cfi->cfi_container;
 191
 192         err = vfs_fsync(host_file, datasync);
 193         if (!err && !datasync)
 194                 err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 195         inode_unlock(coda_inode);
 196
 197         return err;
 198 }
 199
 200 const struct file_operations coda_file_operations = {
 201         .llseek         = generic_file_llseek,
 202         .read_iter      = coda_file_read_iter,
 203         .write_iter     = coda_file_write_iter,
 204         .mmap           = coda_file_mmap,
 205         .open           = coda_open,
 206         .release        = coda_release,
 207         .fsync          = coda_fsync,
 208         .splice_read    = generic_file_splice_read,
 209 };
 210