/*
   *  linux/fs/ext2/file.c
   *
   * Copyright (C) 1992, 1993, 1994, 1995
   * Remy Card (card@masi.ibp.fr)
   * Laboratoire MASI - Institut Blaise Pascal
   * Universite Pierre et Marie Curie (Paris VI)
   *
   *  from
   *
   *  linux/fs/minix/file.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   *  ext2 fs regular file handling primitives
   *
   *  64-bit file support on 64-bit platforms by Jakub Jelinek
   * 	(jj@sunsite.ms.mff.cuni.cz)
   */
  
  #include <linux/time.h>

  #include <linux/pagemap.h>

  #include <linux/dax.h>

  #include <linux/quotaops.h>

  #include "ext2.h"
  #include "xattr.h"
  #include "acl.h"

  #ifdef CONFIG_FS_DAX

  /*
   * The lock ordering for ext2 DAX fault paths is:
   *
   * mmap_sem (MM)
   *   sb_start_pagefault (vfs, freeze)
   *     ext2_inode_info->dax_sem
   *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
   *         ext2_inode_info->truncate_mutex
   *
   * The default page_lock and i_size verification done by non-DAX fault paths
   * is sufficient because ext2 doesn't support hole punching.
   */

  static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  {

  	struct inode *inode = file_inode(vma->vm_file);
  	struct ext2_inode_info *ei = EXT2_I(inode);
  	int ret;
  
  	if (vmf->flags & FAULT_FLAG_WRITE) {
  		sb_start_pagefault(inode->i_sb);
  		file_update_time(vma->vm_file);
  	}
  	down_read(&ei->dax_sem);
  
  	ret = __dax_fault(vma, vmf, ext2_get_block, NULL);
  
  	up_read(&ei->dax_sem);
  	if (vmf->flags & FAULT_FLAG_WRITE)
  		sb_end_pagefault(inode->i_sb);
  	return ret;

  }

  static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
  						pmd_t *pmd, unsigned int flags)
  {

  	struct inode *inode = file_inode(vma->vm_file);
  	struct ext2_inode_info *ei = EXT2_I(inode);
  	int ret;
  
  	if (flags & FAULT_FLAG_WRITE) {
  		sb_start_pagefault(inode->i_sb);
  		file_update_time(vma->vm_file);
  	}
  	down_read(&ei->dax_sem);
  
  	ret = __dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block, NULL);
  
  	up_read(&ei->dax_sem);
  	if (flags & FAULT_FLAG_WRITE)
  		sb_end_pagefault(inode->i_sb);
  	return ret;

  }

  static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
  		struct vm_fault *vmf)
  {
  	struct inode *inode = file_inode(vma->vm_file);
  	struct ext2_inode_info *ei = EXT2_I(inode);

  	loff_t size;

  	int ret;

  
  	sb_start_pagefault(inode->i_sb);
  	file_update_time(vma->vm_file);
  	down_read(&ei->dax_sem);
  
  	/* check that the faulting page hasn't raced with truncate */
  	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	if (vmf->pgoff >= size)
  		ret = VM_FAULT_SIGBUS;

  	else
  		ret = dax_pfn_mkwrite(vma, vmf);

  
  	up_read(&ei->dax_sem);
  	sb_end_pagefault(inode->i_sb);
  	return ret;

  }
  
  static const struct vm_operations_struct ext2_dax_vm_ops = {
  	.fault		= ext2_dax_fault,

  	.pmd_fault	= ext2_dax_pmd_fault,

  	.page_mkwrite	= ext2_dax_fault,

  	.pfn_mkwrite	= ext2_dax_pfn_mkwrite,

  };
  
  static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
  {
  	if (!IS_DAX(file_inode(file)))
  		return generic_file_mmap(file, vma);
  
  	file_accessed(file);
  	vma->vm_ops = &ext2_dax_vm_ops;

  	vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;

  	return 0;
  }
  #else
  #define ext2_file_mmap	generic_file_mmap
  #endif

  /*

   * Called when filp is released. This happens when all file descriptors
   * for a single struct file are closed. Note that different open() calls
   * for the same file yield different struct file structures.

   */
  static int ext2_release_file (struct inode * inode, struct file * filp)
  {

  	if (filp->f_mode & FMODE_WRITE) {
  		mutex_lock(&EXT2_I(inode)->truncate_mutex);
  		ext2_discard_reservation(inode);
  		mutex_unlock(&EXT2_I(inode)->truncate_mutex);
  	}

  	return 0;
  }

  int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)

  {
  	int ret;

  	struct super_block *sb = file->f_mapping->host->i_sb;

  	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;

  	ret = generic_file_fsync(file, start, end, datasync);

  	if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
  		/* We don't really know where the IO error happened... */
  		ext2_error(sb, __func__,
  			   "detected IO error when writing metadata buffers");
  		ret = -EIO;
  	}
  	return ret;
  }

  /*
   * We have mostly NULL's here: the current defaults are ok for
   * the ext2 filesystem.
   */

  const struct file_operations ext2_file_operations = {

  	.llseek		= generic_file_llseek,

  	.read_iter	= generic_file_read_iter,

  	.write_iter	= generic_file_write_iter,

  	.unlocked_ioctl = ext2_ioctl,

  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= ext2_compat_ioctl,
  #endif

  	.mmap		= ext2_file_mmap,

  	.open		= dquot_file_open,

  	.release	= ext2_release_file,

  	.fsync		= ext2_fsync,

  	.splice_read	= generic_file_splice_read,

  	.splice_write	= iter_file_splice_write,

  };

  const struct inode_operations ext2_file_inode_operations = {

  #ifdef CONFIG_EXT2_FS_XATTR
  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,
  	.listxattr	= ext2_listxattr,
  	.removexattr	= generic_removexattr,
  #endif
  	.setattr	= ext2_setattr,

  	.get_acl	= ext2_get_acl,

  	.set_acl	= ext2_set_acl,

  	.fiemap		= ext2_fiemap,

  };