/*

   *  linux/fs/ext4/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
   *

   *  ext4 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/fs.h>

  #include <linux/jbd2.h>

  #include <linux/mount.h>
  #include <linux/path.h>

  #include <linux/quotaops.h>

  #include "ext4.h"
  #include "ext4_jbd2.h"

  #include "xattr.h"
  #include "acl.h"
  
  /*
   * Called when an inode is released. Note that this is different

   * from ext4_file_open: open gets called at every open, but release

   * gets called only when /all/ the files are closed.
   */

  static int ext4_release_file(struct inode *inode, struct file *filp)

  {

  	if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {

  		ext4_alloc_da_blocks(inode);

  		ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);

  	}

  	/* if we are the last writer on the inode, drop the block reservation */
  	if ((filp->f_mode & FMODE_WRITE) &&

  			(atomic_read(&inode->i_writecount) == 1) &&
  		        !EXT4_I(inode)->i_reserved_data_blocks)

  	{

  		down_write(&EXT4_I(inode)->i_data_sem);

  		ext4_discard_preallocations(inode);

  		up_write(&EXT4_I(inode)->i_data_sem);

  	}
  	if (is_dx(inode) && filp->private_data)

  		ext4_htree_free_dir_info(filp->private_data);

  
  	return 0;
  }

  static void ext4_aiodio_wait(struct inode *inode)
  {
  	wait_queue_head_t *wq = ext4_ioend_wq(inode);
  
  	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_aiodio_unwritten) == 0));
  }
  
  /*
   * This tests whether the IO in question is block-aligned or not.
   * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
   * are converted to written only after the IO is complete.  Until they are
   * mapped, these blocks appear as holes, so dio_zero_block() will assume that
   * it needs to zero out portions of the start and/or end block.  If 2 AIO
   * threads are at work on the same unwritten block, they must be synchronized
   * or one thread will zero the other's data, causing corruption.
   */
  static int
  ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
  		   unsigned long nr_segs, loff_t pos)
  {
  	struct super_block *sb = inode->i_sb;
  	int blockmask = sb->s_blocksize - 1;
  	size_t count = iov_length(iov, nr_segs);
  	loff_t final_size = pos + count;
  
  	if (pos >= inode->i_size)
  		return 0;
  
  	if ((pos & blockmask) || (final_size & blockmask))
  		return 1;
  
  	return 0;
  }

  static ssize_t

  ext4_file_write(struct kiocb *iocb, const struct iovec *iov,

  		unsigned long nr_segs, loff_t pos)
  {

  	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;

  	int unaligned_aio = 0;
  	int ret;

  	/*
  	 * If we have encountered a bitmap-format file, the size limit
  	 * is smaller than s_maxbytes, which is for extent-mapped files.
  	 */

  	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {

  		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  		size_t length = iov_length(iov, nr_segs);

  		if ((pos > sbi->s_bitmap_maxbytes ||
  		    (pos == sbi->s_bitmap_maxbytes && length > 0)))

  			return -EFBIG;
  
  		if (pos + length > sbi->s_bitmap_maxbytes) {
  			nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
  					      sbi->s_bitmap_maxbytes - pos);
  		}

  	} else if (unlikely((iocb->ki_filp->f_flags & O_DIRECT) &&
  		   !is_sync_kiocb(iocb))) {
  		unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);

  	}

  	/* Unaligned direct AIO must be serialized; see comment above */
  	if (unaligned_aio) {
  		static unsigned long unaligned_warn_time;
  
  		/* Warn about this once per day */
  		if (printk_timed_ratelimit(&unaligned_warn_time, 60*60*24*HZ))
  			ext4_msg(inode->i_sb, KERN_WARNING,
  				 "Unaligned AIO/DIO on inode %ld by %s; "
  				 "performance will be poor.",
  				 inode->i_ino, current->comm);
  		mutex_lock(ext4_aio_mutex(inode));
  		ext4_aiodio_wait(inode);
  	}
  
  	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
  
  	if (unaligned_aio)
  		mutex_unlock(ext4_aio_mutex(inode));
  
  	return ret;

  }

  static const struct vm_operations_struct ext4_file_vm_ops = {

  	.fault		= filemap_fault,
  	.page_mkwrite   = ext4_page_mkwrite,
  };
  
  static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
  {
  	struct address_space *mapping = file->f_mapping;
  
  	if (!mapping->a_ops->readpage)
  		return -ENOEXEC;
  	file_accessed(file);
  	vma->vm_ops = &ext4_file_vm_ops;
  	vma->vm_flags |= VM_CAN_NONLINEAR;
  	return 0;
  }

  static int ext4_file_open(struct inode * inode, struct file * filp)
  {
  	struct super_block *sb = inode->i_sb;
  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

  	struct ext4_inode_info *ei = EXT4_I(inode);

  	struct vfsmount *mnt = filp->f_path.mnt;
  	struct path path;
  	char buf[64], *cp;
  
  	if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
  		     !(sb->s_flags & MS_RDONLY))) {
  		sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
  		/*
  		 * Sample where the filesystem has been mounted and
  		 * store it in the superblock for sysadmin convenience
  		 * when trying to sort through large numbers of block
  		 * devices or filesystem images.
  		 */
  		memset(buf, 0, sizeof(buf));

  		path.mnt = mnt;
  		path.dentry = mnt->mnt_root;

  		cp = d_path(&path, buf, sizeof(buf));

  		if (!IS_ERR(cp)) {

  			strlcpy(sbi->s_es->s_last_mounted, cp,
  				sizeof(sbi->s_es->s_last_mounted));

  			ext4_mark_super_dirty(sb);

  		}
  	}

  	/*
  	 * Set up the jbd2_inode if we are opening the inode for
  	 * writing and the journal is present
  	 */
  	if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
  		struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);
  
  		spin_lock(&inode->i_lock);
  		if (!ei->jinode) {
  			if (!jinode) {
  				spin_unlock(&inode->i_lock);
  				return -ENOMEM;
  			}
  			ei->jinode = jinode;
  			jbd2_journal_init_jbd_inode(ei->jinode, inode);
  			jinode = NULL;
  		}
  		spin_unlock(&inode->i_lock);
  		if (unlikely(jinode != NULL))
  			jbd2_free_inode(jinode);
  	}

  	return dquot_file_open(inode, filp);

  }

  /*
   * ext4_llseek() copied from generic_file_llseek() to handle both
   * block-mapped and extent-mapped maxbytes values. This should
   * otherwise be identical with generic_file_llseek().
   */
  loff_t ext4_llseek(struct file *file, loff_t offset, int origin)
  {
  	struct inode *inode = file->f_mapping->host;
  	loff_t maxbytes;
  
  	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
  		maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
  	else
  		maxbytes = inode->i_sb->s_maxbytes;

  	return generic_file_llseek_size(file, offset, origin, maxbytes);

  }

  const struct file_operations ext4_file_operations = {

  	.llseek		= ext4_llseek,

  	.read		= do_sync_read,
  	.write		= do_sync_write,
  	.aio_read	= generic_file_aio_read,

  	.aio_write	= ext4_file_write,

  	.unlocked_ioctl = ext4_ioctl,

  #ifdef CONFIG_COMPAT

  	.compat_ioctl	= ext4_compat_ioctl,

  #endif

  	.mmap		= ext4_file_mmap,

  	.open		= ext4_file_open,

  	.release	= ext4_release_file,
  	.fsync		= ext4_sync_file,

  	.splice_read	= generic_file_splice_read,
  	.splice_write	= generic_file_splice_write,

  	.fallocate	= ext4_fallocate,

  };

  const struct inode_operations ext4_file_inode_operations = {

  	.setattr	= ext4_setattr,

  	.getattr	= ext4_getattr,

  #ifdef CONFIG_EXT4_FS_XATTR

  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,

  	.listxattr	= ext4_listxattr,

  	.removexattr	= generic_removexattr,
  #endif

  	.get_acl	= ext4_get_acl,

  	.fiemap		= ext4_fiemap,

  };