linux/fs/coda/file.c
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   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
  29static ssize_t
  30coda_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
  40static ssize_t
  41coda_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
  61static ssize_t
  62coda_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
  84static int
  85coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  86{
  87        struct coda_file_info *cfi;
  88        struct coda_inode_info *cii;
  89        struct file *host_file;
  90        struct inode *coda_inode, *host_inode;
  91
  92        cfi = CODA_FTOC(coda_file);
  93        BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
  94        host_file = cfi->cfi_container;
  95
  96        if (!host_file->f_op->mmap)
  97                return -ENODEV;
  98
  99        coda_inode = file_inode(coda_file);
 100        host_inode = file_inode(host_file);
 101
 102        cii = ITOC(coda_inode);
 103        spin_lock(&cii->c_lock);
 104        coda_file->f_mapping = host_file->f_mapping;
 105        if (coda_inode->i_mapping == &coda_inode->i_data)
 106                coda_inode->i_mapping = host_inode->i_mapping;
 107
 108        /* only allow additional mmaps as long as userspace isn't changing
 109         * the container file on us! */
 110        else if (coda_inode->i_mapping != host_inode->i_mapping) {
 111                spin_unlock(&cii->c_lock);
 112                return -EBUSY;
 113        }
 114
 115        /* keep track of how often the coda_inode/host_file has been mmapped */
 116        cii->c_mapcount++;
 117        cfi->cfi_mapcount++;
 118        spin_unlock(&cii->c_lock);
 119
 120        return host_file->f_op->mmap(host_file, vma);
 121}
 122
 123int coda_open(struct inode *coda_inode, struct file *coda_file)
 124{
 125        struct file *host_file = NULL;
 126        int error;
 127        unsigned short flags = coda_file->f_flags & (~O_EXCL);
 128        unsigned short coda_flags = coda_flags_to_cflags(flags);
 129        struct coda_file_info *cfi;
 130
 131        cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
 132        if (!cfi)
 133                return -ENOMEM;
 134
 135        error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
 136                           &host_file);
 137        if (!host_file)
 138                error = -EIO;
 139
 140        if (error) {
 141                kfree(cfi);
 142                return error;
 143        }
 144
 145        host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
 146
 147        cfi->cfi_magic = CODA_MAGIC;
 148        cfi->cfi_mapcount = 0;
 149        cfi->cfi_container = host_file;
 150
 151        BUG_ON(coda_file->private_data != NULL);
 152        coda_file->private_data = cfi;
 153        return 0;
 154}
 155
 156int coda_release(struct inode *coda_inode, struct file *coda_file)
 157{
 158        unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
 159        unsigned short coda_flags = coda_flags_to_cflags(flags);
 160        struct coda_file_info *cfi;
 161        struct coda_inode_info *cii;
 162        struct inode *host_inode;
 163        int err;
 164
 165        cfi = CODA_FTOC(coda_file);
 166        BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 167
 168        err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
 169                          coda_flags, coda_file->f_cred->fsuid);
 170
 171        host_inode = file_inode(cfi->cfi_container);
 172        cii = ITOC(coda_inode);
 173
 174        /* did we mmap this file? */
 175        spin_lock(&cii->c_lock);
 176        if (coda_inode->i_mapping == &host_inode->i_data) {
 177                cii->c_mapcount -= cfi->cfi_mapcount;
 178                if (!cii->c_mapcount)
 179                        coda_inode->i_mapping = &coda_inode->i_data;
 180        }
 181        spin_unlock(&cii->c_lock);
 182
 183        fput(cfi->cfi_container);
 184        kfree(coda_file->private_data);
 185        coda_file->private_data = NULL;
 186
 187        /* VFS fput ignores the return value from file_operations->release, so
 188         * there is no use returning an error here */
 189        return 0;
 190}
 191
 192int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)
 193{
 194        struct file *host_file;
 195        struct inode *coda_inode = file_inode(coda_file);
 196        struct coda_file_info *cfi;
 197        int err;
 198
 199        if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
 200              S_ISLNK(coda_inode->i_mode)))
 201                return -EINVAL;
 202
 203        err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 204        if (err)
 205                return err;
 206        mutex_lock(&coda_inode->i_mutex);
 207
 208        cfi = CODA_FTOC(coda_file);
 209        BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 210        host_file = cfi->cfi_container;
 211
 212        err = vfs_fsync(host_file, datasync);
 213        if (!err && !datasync)
 214                err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
 215        mutex_unlock(&coda_inode->i_mutex);
 216
 217        return err;
 218}
 219
 220const struct file_operations coda_file_operations = {
 221        .llseek         = generic_file_llseek,
 222        .read_iter      = coda_file_read_iter,
 223        .write_iter     = coda_file_write_iter,
 224        .mmap           = coda_file_mmap,
 225        .open           = coda_open,
 226        .release        = coda_release,
 227        .fsync          = coda_fsync,
 228        .splice_read    = coda_file_splice_read,
 229};
 230
 231