// SPDX-License-Identifier: GPL-2.0

  /*

   * Copyright 1999 Hans Reiser, see reiserfs/README for licensing and copyright
   * details

   */

  #include <linux/time.h>
  #include <linux/pagemap.h>
  #include <linux/buffer_head.h>

  #include "reiserfs.h"

  /*
   * access to tail : when one is going to read tail it must make sure, that is
   * not running.  direct2indirect and indirect2direct can not run concurrently
   */

  /*
   * Converts direct items to an unformatted node. Panics if file has no
   * tail. -ENOSPC if no disk space for conversion
   */
  /*
   * path points to first direct item of the file regardless of how many of
   * them are there
   */

  int direct2indirect(struct reiserfs_transaction_handle *th, struct inode *inode,

  		    struct treepath *path, struct buffer_head *unbh,

  		    loff_t tail_offset)

  {

  	struct super_block *sb = inode->i_sb;
  	struct buffer_head *up_to_date_bh;

  	struct item_head *p_le_ih = tp_item_head(path);

  	unsigned long total_tail = 0;

  
  	/* Key to search for the last byte of the converted item. */
  	struct cpu_key end_key;
  
  	/*
  	 * new indirect item to be inserted or key
  	 * of unfm pointer to be pasted
  	 */
  	struct item_head ind_ih;
  	int blk_size;
  	/* returned value for reiserfs_insert_item and clones */
  	int  retval;
  	/* Handle on an unformatted node that will be inserted in the tree. */
  	unp_t unfm_ptr;

  
  	BUG_ON(!th->t_trans_id);
  
  	REISERFS_SB(sb)->s_direct2indirect++;

  	blk_size = sb->s_blocksize;

  	/*
  	 * and key to search for append or insert pointer to the new
  	 * unformatted node.
  	 */

  	copy_item_head(&ind_ih, p_le_ih);
  	set_le_ih_k_offset(&ind_ih, tail_offset);
  	set_le_ih_k_type(&ind_ih, TYPE_INDIRECT);
  
  	/* Set the key to search for the place for new unfm pointer */
  	make_cpu_key(&end_key, inode, tail_offset, TYPE_INDIRECT, 4);

  	/* FIXME: we could avoid this */

  	if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {

  		reiserfs_error(sb, "PAP-14030",
  			       "pasted or inserted byte exists in "
  			       "the tree %K. Use fsck to repair.", &end_key);

  		pathrelse(path);
  		return -EIO;
  	}

  	p_le_ih = tp_item_head(path);

  
  	unfm_ptr = cpu_to_le32(unbh->b_blocknr);
  
  	if (is_statdata_le_ih(p_le_ih)) {
  		/* Insert new indirect item. */
  		set_ih_free_space(&ind_ih, 0);	/* delete at nearest future */
  		put_ih_item_len(&ind_ih, UNFM_P_SIZE);
  		PATH_LAST_POSITION(path)++;

  		retval =

  		    reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,

  					 (char *)&unfm_ptr);

  	} else {

  		/* Paste into last indirect item of an object. */

  		retval = reiserfs_paste_into_item(th, path, &end_key, inode,

  						    (char *)&unfm_ptr,
  						    UNFM_P_SIZE);

  	}

  	if (retval) {
  		return retval;

  	}

  	/*
  	 * note: from here there are two keys which have matching first
  	 *  three key components. They only differ by the fourth one.
  	 */

  
  	/* Set the key to search for the direct items of the file */
  	make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
  		     4);

  	/*
  	 * Move bytes from the direct items to the new unformatted node
  	 * and delete them.
  	 */

  	while (1) {
  		int tail_size;

  		/*
  		 * end_key.k_offset is set so, that we will always have found
  		 * last item of the file
  		 */

  		if (search_for_position_by_key(sb, &end_key, path) ==
  		    POSITION_FOUND)

  			reiserfs_panic(sb, "PAP-14050",

  				       "direct item (%K) not found", &end_key);

  		p_le_ih = tp_item_head(path);

  		RFALSE(!is_direct_le_ih(p_le_ih),
  		       "vs-14055: direct item expected(%K), found %h",
  		       &end_key, p_le_ih);

  		tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))

  		    + ih_item_len(p_le_ih) - 1;

  		/*
  		 * we only send the unbh pointer if the buffer is not
  		 * up to date.  this avoids overwriting good data from
  		 * writepage() with old data from the disk or buffer cache
  		 * Special case: unbh->b_page will be NULL if we are coming
  		 * through DIRECT_IO handler here.

  		 */
  		if (!unbh->b_page || buffer_uptodate(unbh)
  		    || PageUptodate(unbh->b_page)) {
  			up_to_date_bh = NULL;
  		} else {
  			up_to_date_bh = unbh;
  		}

  		retval = reiserfs_delete_item(th, path, &end_key, inode,

  						up_to_date_bh);

  		total_tail += retval;

  
  		/* done: file does not have direct items anymore */

  		if (tail_size == retval)

  			break;

  	}

  	/*
  	 * if we've copied bytes from disk into the page, we need to zero
  	 * out the unused part of the block (it was not up to date before)

  	 */
  	if (up_to_date_bh) {
  		unsigned pgoff =

  		    (tail_offset + total_tail - 1) & (PAGE_SIZE - 1);

  		char *kaddr = kmap_atomic(up_to_date_bh->b_page);

  		memset(kaddr + pgoff, 0, blk_size - total_tail);

  		kunmap_atomic(kaddr);

  	}
  
  	REISERFS_I(inode)->i_first_direct_byte = U32_MAX;
  
  	return 0;
  }

  
  /* stolen from fs/buffer.c */

  void reiserfs_unmap_buffer(struct buffer_head *bh)
  {
  	lock_buffer(bh);
  	if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
  		BUG();
  	}
  	clear_buffer_dirty(bh);

  	/*
  	 * Remove the buffer from whatever list it belongs to. We are mostly
  	 * interested in removing it from per-sb j_dirty_buffers list, to avoid
  	 * BUG() on attempt to write not mapped buffer
  	 */

  	if ((!list_empty(&bh->b_assoc_buffers) || bh->b_private) && bh->b_page) {
  		struct inode *inode = bh->b_page->mapping->host;
  		struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
  		spin_lock(&j->j_dirty_buffers_lock);
  		list_del_init(&bh->b_assoc_buffers);
  		reiserfs_free_jh(bh);
  		spin_unlock(&j->j_dirty_buffers_lock);
  	}
  	clear_buffer_mapped(bh);
  	clear_buffer_req(bh);
  	clear_buffer_new(bh);
  	bh->b_bdev = NULL;
  	unlock_buffer(bh);

  }

  /*
   * this first locks inode (neither reads nor sync are permitted),
   * reads tail through page cache, insert direct item. When direct item
   * inserted successfully inode is left locked. Return value is always
   * what we expect from it (number of cut bytes). But when tail remains
   * in the unformatted node, we set mode to SKIP_BALANCING and unlock
   * inode
   */

  int indirect2direct(struct reiserfs_transaction_handle *th,
  		    struct inode *inode, struct page *page,

  		    struct treepath *path,	/* path to the indirect item. */
  		    const struct cpu_key *item_key,	/* Key to look for
  							 * unformatted node
  							 * pointer to be cut. */

  		    loff_t n_new_file_size,	/* New file size. */

  		    char *mode)

  {

  	struct super_block *sb = inode->i_sb;

  	struct item_head s_ih;

  	unsigned long block_size = sb->s_blocksize;

  	char *tail;
  	int tail_len, round_tail_len;
  	loff_t pos, pos1;	/* position of first byte of the tail */
  	struct cpu_key key;

  	BUG_ON(!th->t_trans_id);

  	REISERFS_SB(sb)->s_indirect2direct++;

  	*mode = M_SKIP_BALANCING;

  	/* store item head path points to. */

  	copy_item_head(&s_ih, tp_item_head(path));

  	tail_len = (n_new_file_size & (block_size - 1));

  	if (get_inode_sd_version(inode) == STAT_DATA_V2)

  		round_tail_len = ROUND_UP(tail_len);
  	else
  		round_tail_len = tail_len;
  
  	pos =
  	    le_ih_k_offset(&s_ih) - 1 + (ih_item_len(&s_ih) / UNFM_P_SIZE -

  					 1) * sb->s_blocksize;

  	pos1 = pos;

  	/*
  	 * we are protected by i_mutex. The tail can not disapper, not
  	 * append can be done either
  	 * we are in truncate or packing tail in file_release
  	 */

  
  	tail = (char *)kmap(page);	/* this can schedule */

  	if (path_changed(&s_ih, path)) {

  		/* re-search indirect item */

  		if (search_for_position_by_key(sb, item_key, path)

  		    == POSITION_NOT_FOUND)

  			reiserfs_panic(sb, "PAP-5520",

  				       "item to be converted %K does not exist",

  				       item_key);

  		copy_item_head(&s_ih, tp_item_head(path));

  #ifdef CONFIG_REISERFS_CHECK

  		pos = le_ih_k_offset(&s_ih) - 1 +
  		    (ih_item_len(&s_ih) / UNFM_P_SIZE -

  		     1) * sb->s_blocksize;

  		if (pos != pos1)

  			reiserfs_panic(sb, "vs-5530", "tail position "

  				       "changed while we were reading it");

  #endif

  	}

  	/* Set direct item header to insert. */

  	make_le_item_head(&s_ih, NULL, get_inode_item_key_version(inode),

  			  pos1 + 1, TYPE_DIRECT, round_tail_len,
  			  0xffff /*ih_free_space */ );

  	/*
  	 * we want a pointer to the first byte of the tail in the page.
  	 * the page was locked and this part of the page was up to date when
  	 * indirect2direct was called, so we know the bytes are still valid

  	 */

  	tail = tail + (pos & (PAGE_SIZE - 1));

  	PATH_LAST_POSITION(path)++;

  	key = *item_key;

  	set_cpu_key_k_type(&key, TYPE_DIRECT);
  	key.key_length = 4;
  	/* Insert tail as new direct item in the tree */

  	if (reiserfs_insert_item(th, path, &key, &s_ih, inode,

  				 tail ? tail : NULL) < 0) {

  		/*
  		 * No disk memory. So we can not convert last unformatted node
  		 * to the direct item.  In this case we used to adjust
  		 * indirect items's ih_free_space. Now ih_free_space is not
  		 * used, it would be ideal to write zeros to corresponding
  		 * unformatted node. For now i_size is considered as guard for
  		 * going out of file size
  		 */

  		kunmap(page);

  		return block_size - round_tail_len;

  	}
  	kunmap(page);

  	/* make sure to get the i_blocks changes from reiserfs_insert_item */

  	reiserfs_update_sd(th, inode);

  	/*
  	 * note: we have now the same as in above direct2indirect
  	 * conversion: there are two keys which have matching first three
  	 * key components. They only differ by the fourth one.
  	 */

  	/*
  	 * We have inserted new direct item and must remove last
  	 * unformatted node.
  	 */

  	*mode = M_CUT;

  	/* we store position of first direct item in the in-core inode */

  	/* mark_file_with_tail (inode, pos1 + 1); */
  	REISERFS_I(inode)->i_first_direct_byte = pos1 + 1;

  	return block_size - round_tail_len;

  }