// SPDX-License-Identifier: GPL-2.0

  /*
   * File operations for Coda.
   * Original version: (C) 1996 Peter Braam 
   * Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
   *
   * Carnegie Mellon encourages users of this code to contribute improvements
   * to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
   */
  
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/time.h>
  #include <linux/file.h>
  #include <linux/fs.h>
  #include <linux/stat.h>

  #include <linux/cred.h>

  #include <linux/errno.h>

  #include <linux/spinlock.h>

  #include <linux/string.h>

  #include <linux/slab.h>

  #include <linux/uaccess.h>

  #include <linux/uio.h>

  
  #include <linux/coda.h>

  #include "coda_psdev.h"

  #include "coda_linux.h"

  #include "coda_int.h"

  struct coda_vm_ops {
  	atomic_t refcnt;
  	struct file *coda_file;
  	const struct vm_operations_struct *host_vm_ops;
  	struct vm_operations_struct vm_ops;
  };

  static ssize_t

  coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

  {

  	struct file *coda_file = iocb->ki_filp;

  	struct inode *coda_inode = file_inode(coda_file);

  	struct coda_file_info *cfi = coda_ftoc(coda_file);

  	loff_t ki_pos = iocb->ki_pos;
  	size_t count = iov_iter_count(to);
  	ssize_t ret;
  
  	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  				  &cfi->cfi_access_intent,
  				  count, ki_pos, CODA_ACCESS_TYPE_READ);
  	if (ret)
  		goto finish_read;
  
  	ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);

  finish_read:
  	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  			    &cfi->cfi_access_intent,
  			    count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
  	return ret;

  }
  
  static ssize_t

  coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)

  {

  	struct file *coda_file = iocb->ki_filp;
  	struct inode *coda_inode = file_inode(coda_file);

  	struct coda_file_info *cfi = coda_ftoc(coda_file);

  	struct file *host_file = cfi->cfi_container;
  	loff_t ki_pos = iocb->ki_pos;
  	size_t count = iov_iter_count(to);

  	ssize_t ret;

  	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  				  &cfi->cfi_access_intent,
  				  count, ki_pos, CODA_ACCESS_TYPE_WRITE);
  	if (ret)
  		goto finish_write;

  	file_start_write(host_file);

  	inode_lock(coda_inode);

  	ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);

  	coda_inode->i_size = file_inode(host_file)->i_size;

  	coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;

  	coda_inode->i_mtime = coda_inode->i_ctime = current_time(coda_inode);

  	inode_unlock(coda_inode);

  	file_end_write(host_file);

  
  finish_write:
  	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  			    &cfi->cfi_access_intent,
  			    count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);

  	return ret;
  }

  static void
  coda_vm_open(struct vm_area_struct *vma)
  {
  	struct coda_vm_ops *cvm_ops =
  		container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
  
  	atomic_inc(&cvm_ops->refcnt);
  
  	if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
  		cvm_ops->host_vm_ops->open(vma);
  }
  
  static void
  coda_vm_close(struct vm_area_struct *vma)
  {
  	struct coda_vm_ops *cvm_ops =
  		container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
  
  	if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
  		cvm_ops->host_vm_ops->close(vma);
  
  	if (atomic_dec_and_test(&cvm_ops->refcnt)) {
  		vma->vm_ops = cvm_ops->host_vm_ops;
  		fput(cvm_ops->coda_file);
  		kfree(cvm_ops);
  	}
  }

  static int
  coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
  {

  	struct inode *coda_inode = file_inode(coda_file);
  	struct coda_file_info *cfi = coda_ftoc(coda_file);
  	struct file *host_file = cfi->cfi_container;
  	struct inode *host_inode = file_inode(host_file);

  	struct coda_inode_info *cii;

  	struct coda_vm_ops *cvm_ops;

  	loff_t ppos;
  	size_t count;

  	int ret;

  	if (!host_file->f_op->mmap)

  		return -ENODEV;

  	if (WARN_ON(coda_file != vma->vm_file))
  		return -EIO;

  	count = vma->vm_end - vma->vm_start;
  	ppos = vma->vm_pgoff * PAGE_SIZE;
  
  	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
  				  &cfi->cfi_access_intent,
  				  count, ppos, CODA_ACCESS_TYPE_MMAP);
  	if (ret)
  		return ret;

  	cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
  	if (!cvm_ops)
  		return -ENOMEM;

  	cii = ITOC(coda_inode);
  	spin_lock(&cii->c_lock);

  	coda_file->f_mapping = host_file->f_mapping;
  	if (coda_inode->i_mapping == &coda_inode->i_data)
  		coda_inode->i_mapping = host_inode->i_mapping;
  
  	/* only allow additional mmaps as long as userspace isn't changing
  	 * the container file on us! */

  	else if (coda_inode->i_mapping != host_inode->i_mapping) {
  		spin_unlock(&cii->c_lock);

  		kfree(cvm_ops);

  		return -EBUSY;

  	}

  
  	/* keep track of how often the coda_inode/host_file has been mmapped */

  	cii->c_mapcount++;
  	cfi->cfi_mapcount++;

  	spin_unlock(&cii->c_lock);

  	vma->vm_file = get_file(host_file);
  	ret = call_mmap(vma->vm_file, vma);
  
  	if (ret) {
  		/* if call_mmap fails, our caller will put coda_file so we
  		 * should drop the reference to the host_file that we got.
  		 */
  		fput(host_file);
  		kfree(cvm_ops);
  	} else {
  		/* here we add redirects for the open/close vm_operations */
  		cvm_ops->host_vm_ops = vma->vm_ops;
  		if (vma->vm_ops)
  			cvm_ops->vm_ops = *vma->vm_ops;
  
  		cvm_ops->vm_ops.open = coda_vm_open;
  		cvm_ops->vm_ops.close = coda_vm_close;
  		cvm_ops->coda_file = coda_file;
  		atomic_set(&cvm_ops->refcnt, 1);
  
  		vma->vm_ops = &cvm_ops->vm_ops;
  	}
  	return ret;

  }
  
  int coda_open(struct inode *coda_inode, struct file *coda_file)
  {
  	struct file *host_file = NULL;
  	int error;
  	unsigned short flags = coda_file->f_flags & (~O_EXCL);
  	unsigned short coda_flags = coda_flags_to_cflags(flags);
  	struct coda_file_info *cfi;

  	cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);

  	if (!cfi)

  		return -ENOMEM;

  	error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,

  			   &host_file);
  	if (!host_file)
  		error = -EIO;
  
  	if (error) {

  		kfree(cfi);

  		return error;
  	}
  
  	host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
  
  	cfi->cfi_magic = CODA_MAGIC;
  	cfi->cfi_mapcount = 0;
  	cfi->cfi_container = host_file;

  	/* assume access intents are supported unless we hear otherwise */
  	cfi->cfi_access_intent = true;

  
  	BUG_ON(coda_file->private_data != NULL);
  	coda_file->private_data = cfi;

  	return 0;
  }

  int coda_release(struct inode *coda_inode, struct file *coda_file)
  {
  	unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
  	unsigned short coda_flags = coda_flags_to_cflags(flags);
  	struct coda_file_info *cfi;
  	struct coda_inode_info *cii;
  	struct inode *host_inode;

  	int err;

  	cfi = coda_ftoc(coda_file);

  	err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),

  			  coda_flags, coda_file->f_cred->fsuid);

  	host_inode = file_inode(cfi->cfi_container);

  	cii = ITOC(coda_inode);
  
  	/* did we mmap this file? */

  	spin_lock(&cii->c_lock);

  	if (coda_inode->i_mapping == &host_inode->i_data) {
  		cii->c_mapcount -= cfi->cfi_mapcount;
  		if (!cii->c_mapcount)
  			coda_inode->i_mapping = &coda_inode->i_data;
  	}

  	spin_unlock(&cii->c_lock);

  
  	fput(cfi->cfi_container);
  	kfree(coda_file->private_data);
  	coda_file->private_data = NULL;

  	/* VFS fput ignores the return value from file_operations->release, so
  	 * there is no use returning an error here */
  	return 0;

  }

  int coda_fsync(struct file *coda_file, loff_t start, loff_t end, int datasync)

  {
  	struct file *host_file;

  	struct inode *coda_inode = file_inode(coda_file);

  	struct coda_file_info *cfi;

  	int err;

  
  	if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
  	      S_ISLNK(coda_inode->i_mode)))
  		return -EINVAL;

  	err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
  	if (err)
  		return err;

  	inode_lock(coda_inode);

  	cfi = coda_ftoc(coda_file);

  	host_file = cfi->cfi_container;

  	err = vfs_fsync(host_file, datasync);

  	if (!err && !datasync)

  		err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));

  	inode_unlock(coda_inode);

  
  	return err;
  }

  const struct file_operations coda_file_operations = {

  	.llseek		= generic_file_llseek,

  	.read_iter	= coda_file_read_iter,
  	.write_iter	= coda_file_write_iter,

  	.mmap		= coda_file_mmap,
  	.open		= coda_open,

  	.release	= coda_release,
  	.fsync		= coda_fsync,

  	.splice_read	= generic_file_splice_read,

  };