/*
   * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.

   * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.

   *
   * This copyrighted material is made available to anyone wishing to use,
   * modify, copy, or redistribute it subject to the terms and conditions

   * of the GNU General Public License version 2.

   */
  
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/buffer_head.h>
  #include <linux/mm.h>
  #include <linux/pagemap.h>
  #include <linux/writeback.h>
  #include <linux/swap.h>
  #include <linux/delay.h>

  #include <linux/bio.h>

  #include <linux/gfs2_ondisk.h>

  #include <linux/lm_interface.h>

  
  #include "gfs2.h"

  #include "incore.h"

  #include "glock.h"
  #include "glops.h"
  #include "inode.h"
  #include "log.h"
  #include "lops.h"
  #include "meta_io.h"
  #include "rgrp.h"
  #include "trans.h"

  #include "util.h"

  #include "ops_address.h"

  static int aspace_get_block(struct inode *inode, sector_t lblock,
  			    struct buffer_head *bh_result, int create)
  {

  	gfs2_assert_warn(inode->i_sb->s_fs_info, 0);

  	return -EOPNOTSUPP;
  }
  
  static int gfs2_aspace_writepage(struct page *page,
  				 struct writeback_control *wbc)
  {
  	return block_write_full_page(page, aspace_get_block, wbc);
  }

  static const struct address_space_operations aspace_aops = {

  	.writepage = gfs2_aspace_writepage,

  	.releasepage = gfs2_releasepage,

  };
  
  /**
   * gfs2_aspace_get - Create and initialize a struct inode structure
   * @sdp: the filesystem the aspace is in
   *
   * Right now a struct inode is just a struct inode.  Maybe Linux
   * will supply a more lightweight address space construct (that works)
   * in the future.
   *
   * Make sure pages/buffers in this aspace aren't in high memory.
   *
   * Returns: the aspace
   */
  
  struct inode *gfs2_aspace_get(struct gfs2_sbd *sdp)
  {
  	struct inode *aspace;
  
  	aspace = new_inode(sdp->sd_vfs);
  	if (aspace) {

  		mapping_set_gfp_mask(aspace->i_mapping, GFP_NOFS);

  		aspace->i_mapping->a_ops = &aspace_aops;
  		aspace->i_size = ~0ULL;

  		aspace->i_private = NULL;

  		insert_inode_hash(aspace);
  	}

  	return aspace;
  }
  
  void gfs2_aspace_put(struct inode *aspace)
  {
  	remove_inode_hash(aspace);
  	iput(aspace);
  }
  
  /**

   * gfs2_meta_inval - Invalidate all buffers associated with a glock
   * @gl: the glock
   *
   */
  
  void gfs2_meta_inval(struct gfs2_glock *gl)
  {
  	struct gfs2_sbd *sdp = gl->gl_sbd;
  	struct inode *aspace = gl->gl_aspace;
  	struct address_space *mapping = gl->gl_aspace->i_mapping;
  
  	gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
  
  	atomic_inc(&aspace->i_writecount);
  	truncate_inode_pages(mapping, 0);
  	atomic_dec(&aspace->i_writecount);
  
  	gfs2_assert_withdraw(sdp, !mapping->nrpages);
  }
  
  /**
   * gfs2_meta_sync - Sync all buffers associated with a glock
   * @gl: The glock

   *
   */

  void gfs2_meta_sync(struct gfs2_glock *gl)

  {
  	struct address_space *mapping = gl->gl_aspace->i_mapping;

  	int error;

  	filemap_fdatawrite(mapping);
  	error = filemap_fdatawait(mapping);

  
  	if (error)
  		gfs2_io_error(gl->gl_sbd);
  }
  
  /**
   * getbuf - Get a buffer with a given address space

   * @gl: the glock

   * @blkno: the block number (filesystem scope)
   * @create: 1 if the buffer should be created
   *
   * Returns: the buffer
   */

  static struct buffer_head *getbuf(struct gfs2_glock *gl, u64 blkno, int create)

  {

  	struct address_space *mapping = gl->gl_aspace->i_mapping;
  	struct gfs2_sbd *sdp = gl->gl_sbd;

  	struct page *page;
  	struct buffer_head *bh;
  	unsigned int shift;
  	unsigned long index;
  	unsigned int bufnum;
  
  	shift = PAGE_CACHE_SHIFT - sdp->sd_sb.sb_bsize_shift;
  	index = blkno >> shift;             /* convert block to page */
  	bufnum = blkno - (index << shift);  /* block buf index within page */
  
  	if (create) {
  		for (;;) {

  			page = grab_cache_page(mapping, index);

  			if (page)
  				break;
  			yield();
  		}
  	} else {

  		page = find_lock_page(mapping, index);

  		if (!page)
  			return NULL;
  	}
  
  	if (!page_has_buffers(page))
  		create_empty_buffers(page, sdp->sd_sb.sb_bsize, 0);
  
  	/* Locate header for our buffer within our page */
  	for (bh = page_buffers(page); bufnum--; bh = bh->b_this_page)
  		/* Do nothing */;
  	get_bh(bh);
  
  	if (!buffer_mapped(bh))
  		map_bh(bh, sdp->sd_vfs, blkno);
  
  	unlock_page(page);
  	mark_page_accessed(page);
  	page_cache_release(page);
  
  	return bh;
  }
  
  static void meta_prep_new(struct buffer_head *bh)
  {
  	struct gfs2_meta_header *mh = (struct gfs2_meta_header *)bh->b_data;
  
  	lock_buffer(bh);
  	clear_buffer_dirty(bh);
  	set_buffer_uptodate(bh);
  	unlock_buffer(bh);
  
  	mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
  }
  
  /**
   * gfs2_meta_new - Get a block
   * @gl: The glock associated with this block
   * @blkno: The block number
   *
   * Returns: The buffer
   */

  struct buffer_head *gfs2_meta_new(struct gfs2_glock *gl, u64 blkno)

  {
  	struct buffer_head *bh;

  	bh = getbuf(gl, blkno, CREATE);

  	meta_prep_new(bh);
  	return bh;
  }
  
  /**
   * gfs2_meta_read - Read a block from disk
   * @gl: The glock covering the block
   * @blkno: The block number

   * @flags: flags

   * @bhp: the place where the buffer is returned (NULL on failure)
   *
   * Returns: errno
   */

  int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,

  		   struct buffer_head **bhp)
  {

  	*bhp = getbuf(gl, blkno, CREATE);

  	if (!buffer_uptodate(*bhp))

  		ll_rw_block(READ_META, 1, bhp);

  	if (flags & DIO_WAIT) {
  		int error = gfs2_meta_wait(gl->gl_sbd, *bhp);
  		if (error) {
  			brelse(*bhp);
  			return error;
  		}
  	}

  	return 0;

  }
  
  /**

   * gfs2_meta_wait - Reread a block from disk

   * @sdp: the filesystem

   * @bh: The block to wait for

   *
   * Returns: errno
   */

  int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)

  {
  	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
  		return -EIO;

  	wait_on_buffer(bh);

  	if (!buffer_uptodate(bh)) {
  		struct gfs2_trans *tr = current->journal_info;
  		if (tr && tr->tr_touched)
  			gfs2_io_error_bh(sdp, bh);
  		return -EIO;

  	}

  	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
  		return -EIO;

  
  	return 0;
  }
  
  /**

   * gfs2_attach_bufdata - attach a struct gfs2_bufdata structure to a buffer

   * @gl: the glock the buffer belongs to
   * @bh: The buffer to be attached to

   * @meta: Flag to indicate whether its metadata or not

   */

  void gfs2_attach_bufdata(struct gfs2_glock *gl, struct buffer_head *bh,
  			 int meta)

  {
  	struct gfs2_bufdata *bd;

  	if (meta)
  		lock_page(bh->b_page);

  	if (bh->b_private) {

  		if (meta)
  			unlock_page(bh->b_page);

  		return;
  	}

  	bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL),

  	bd->bd_bh = bh;
  	bd->bd_gl = gl;
  
  	INIT_LIST_HEAD(&bd->bd_list_tr);

  	if (meta)

  		lops_init_le(&bd->bd_le, &gfs2_buf_lops);

  	else

  		lops_init_le(&bd->bd_le, &gfs2_databuf_lops);

  	bh->b_private = bd;

  	if (meta)
  		unlock_page(bh->b_page);

  }
  
  /**

   * gfs2_pin - Pin a buffer in memory

   * @sdp: the filesystem the buffer belongs to
   * @bh: The buffer to be pinned
   *
   */

  void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)

  {

  	struct gfs2_bufdata *bd = bh->b_private;

  
  	gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));
  
  	if (test_set_buffer_pinned(bh))
  		gfs2_assert_withdraw(sdp, 0);
  
  	wait_on_buffer(bh);
  
  	/* If this buffer is in the AIL and it has already been written
  	   to in-place disk block, remove it from the AIL. */
  
  	gfs2_log_lock(sdp);
  	if (bd->bd_ail && !buffer_in_io(bh))
  		list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
  	gfs2_log_unlock(sdp);
  
  	clear_buffer_dirty(bh);
  	wait_on_buffer(bh);
  
  	if (!buffer_uptodate(bh))
  		gfs2_io_error_bh(sdp, bh);
  
  	get_bh(bh);
  }
  
  /**

   * gfs2_unpin - Unpin a buffer

   * @sdp: the filesystem the buffer belongs to
   * @bh: The buffer to unpin
   * @ai:
   *
   */

  void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
  	        struct gfs2_ail *ai)

  {

  	struct gfs2_bufdata *bd = bh->b_private;

  
  	gfs2_assert_withdraw(sdp, buffer_uptodate(bh));
  
  	if (!buffer_pinned(bh))
  		gfs2_assert_withdraw(sdp, 0);
  
  	mark_buffer_dirty(bh);
  	clear_buffer_pinned(bh);
  
  	gfs2_log_lock(sdp);
  	if (bd->bd_ail) {
  		list_del(&bd->bd_ail_st_list);
  		brelse(bh);
  	} else {
  		struct gfs2_glock *gl = bd->bd_gl;
  		list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
  		atomic_inc(&gl->gl_ail_count);
  	}
  	bd->bd_ail = ai;
  	list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
  	gfs2_log_unlock(sdp);
  }
  
  /**
   * gfs2_meta_wipe - make inode's buffers so they aren't dirty/pinned anymore
   * @ip: the inode who owns the buffers
   * @bstart: the first buffer in the run
   * @blen: the number of buffers in the run
   *
   */

  void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)

  {

  	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

  	struct buffer_head *bh;
  
  	while (blen) {

  		bh = getbuf(ip->i_gl, bstart, NO_CREATE);

  		if (bh) {

  			struct gfs2_bufdata *bd = bh->b_private;

  
  			if (test_clear_buffer_pinned(bh)) {

  				struct gfs2_trans *tr = current->journal_info;

  				struct gfs2_inode *bh_ip =
  					GFS2_I(bh->b_page->mapping->host);

  				gfs2_log_lock(sdp);
  				list_del_init(&bd->bd_le.le_list);
  				gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
  				sdp->sd_log_num_buf--;
  				gfs2_log_unlock(sdp);

  				if (bh_ip->i_inode.i_private != NULL)
  					tr->tr_num_databuf_rm++;
  				else
  					tr->tr_num_buf_rm++;

  				brelse(bh);
  			}
  			if (bd) {
  				gfs2_log_lock(sdp);
  				if (bd->bd_ail) {

  					u64 blkno = bh->b_blocknr;

  					bd->bd_ail = NULL;
  					list_del(&bd->bd_ail_st_list);
  					list_del(&bd->bd_ail_gl_list);
  					atomic_dec(&bd->bd_gl->gl_ail_count);
  					brelse(bh);
  					gfs2_log_unlock(sdp);
  					gfs2_trans_add_revoke(sdp, blkno);
  				} else
  					gfs2_log_unlock(sdp);
  			}
  
  			lock_buffer(bh);
  			clear_buffer_dirty(bh);
  			clear_buffer_uptodate(bh);
  			unlock_buffer(bh);
  
  			brelse(bh);
  		}
  
  		bstart++;
  		blen--;
  	}
  }
  
  /**
   * gfs2_meta_cache_flush - get rid of any references on buffers for this inode
   * @ip: The GFS2 inode
   *
   * This releases buffers that are in the most-recently-used array of
   * blocks used for indirect block addressing for this inode.
   */
  
  void gfs2_meta_cache_flush(struct gfs2_inode *ip)
  {
  	struct buffer_head **bh_slot;
  	unsigned int x;
  
  	spin_lock(&ip->i_spin);
  
  	for (x = 0; x < GFS2_MAX_META_HEIGHT; x++) {
  		bh_slot = &ip->i_cache[x];
  		if (!*bh_slot)
  			break;
  		brelse(*bh_slot);
  		*bh_slot = NULL;
  	}
  
  	spin_unlock(&ip->i_spin);
  }
  
  /**
   * gfs2_meta_indirect_buffer - Get a metadata buffer
   * @ip: The GFS2 inode
   * @height: The level of this buf in the metadata (indir addr) tree (if any)
   * @num: The block number (device relative) of the buffer
   * @new: Non-zero if we may create a new buffer
   * @bhp: the buffer is returned here
   *
   * Try to use the gfs2_inode's MRU metadata tree cache.
   *
   * Returns: errno
   */

  int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, u64 num,

  			      int new, struct buffer_head **bhp)
  {

  	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
  	struct gfs2_glock *gl = ip->i_gl;
  	struct buffer_head *bh = NULL, **bh_slot = ip->i_cache + height;
  	int in_cache = 0;

  	BUG_ON(!gl);
  	BUG_ON(!sdp);

  	spin_lock(&ip->i_spin);

  	if (*bh_slot && (*bh_slot)->b_blocknr == num) {
  		bh = *bh_slot;
  		get_bh(bh);
  		in_cache = 1;

  	}
  	spin_unlock(&ip->i_spin);

  	if (!bh)

  		bh = getbuf(gl, num, CREATE);

  	if (!bh)
  		return -ENOBUFS;

  
  	if (new) {

  		if (gfs2_assert_warn(sdp, height))
  			goto err;
  		meta_prep_new(bh);

  		gfs2_trans_add_bh(ip->i_gl, bh, 1);

  		gfs2_metatype_set(bh, GFS2_METATYPE_IN, GFS2_FORMAT_IN);
  		gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header));

  	} else {
  		u32 mtype = height ? GFS2_METATYPE_IN : GFS2_METATYPE_DI;
  		if (!buffer_uptodate(bh)) {

  			ll_rw_block(READ_META, 1, &bh);

  			if (gfs2_meta_wait(sdp, bh))
  				goto err;
  		}
  		if (gfs2_metatype_check(sdp, bh, mtype))
  			goto err;
  	}

  	if (!in_cache) {
  		spin_lock(&ip->i_spin);
  		if (*bh_slot)
  			brelse(*bh_slot);
  		*bh_slot = bh;
  		get_bh(bh);
  		spin_unlock(&ip->i_spin);

  	}
  
  	*bhp = bh;

  	return 0;

  err:
  	brelse(bh);
  	return -EIO;

  }
  
  /**
   * gfs2_meta_ra - start readahead on an extent of a file
   * @gl: the glock the blocks belong to
   * @dblock: the starting disk block
   * @extlen: the number of blocks in the extent
   *

   * returns: the first buffer in the extent

   */

  struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)

  {
  	struct gfs2_sbd *sdp = gl->gl_sbd;

  	struct buffer_head *first_bh, *bh;

  	u32 max_ra = gfs2_tune_get(sdp, gt_max_readahead) >>

  			  sdp->sd_sb.sb_bsize_shift;

  	BUG_ON(!extlen);
  
  	if (max_ra < 1)
  		max_ra = 1;

  	if (extlen > max_ra)
  		extlen = max_ra;

  	first_bh = getbuf(gl, dblock, CREATE);

  
  	if (buffer_uptodate(first_bh))
  		goto out;

  	if (!buffer_locked(first_bh))

  		ll_rw_block(READ_META, 1, &first_bh);

  
  	dblock++;
  	extlen--;
  
  	while (extlen) {

  		bh = getbuf(gl, dblock, CREATE);

  		if (!buffer_uptodate(bh) && !buffer_locked(bh))
  			ll_rw_block(READA, 1, &bh);
  		brelse(bh);

  		dblock++;
  		extlen--;

  		if (!buffer_locked(first_bh) && buffer_uptodate(first_bh))
  			goto out;

  	}

  	wait_on_buffer(first_bh);

  out:

  	return first_bh;

  }