text: /* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * move_extents.c
   *
   * Copyright (C) 2011 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   */
  #include <linux/fs.h>
  #include <linux/types.h>
  #include <linux/mount.h>
  #include <linux/swap.h>
  
  #include <cluster/masklog.h>
  
  #include "ocfs2.h"
  #include "ocfs2_ioctl.h"
  
  #include "alloc.h"
  #include "aops.h"
  #include "dlmglue.h"
  #include "extent_map.h"
  #include "inode.h"
  #include "journal.h"
  #include "suballoc.h"
  #include "uptodate.h"
  #include "super.h"
  #include "dir.h"
  #include "buffer_head_io.h"
  #include "sysfile.h"
  #include "suballoc.h"
  #include "refcounttree.h"
  #include "move_extents.h"
  
  struct ocfs2_move_extents_context {
  	struct inode *inode;
  	struct file *file;
  	int auto_defrag;
  	int partial;
  	int credits;
  	u32 new_phys_cpos;
  	u32 clusters_moved;
  	u64 refcount_loc;
  	struct ocfs2_move_extents *range;
  	struct ocfs2_extent_tree et;
  	struct ocfs2_alloc_context *meta_ac;
  	struct ocfs2_alloc_context *data_ac;
  	struct ocfs2_cached_dealloc_ctxt dealloc;
  };
  
  static int __ocfs2_move_extent(handle_t *handle,
  			       struct ocfs2_move_extents_context *context,
  			       u32 cpos, u32 len, u32 p_cpos, u32 new_p_cpos,
  			       int ext_flags)
  {
  	int ret = 0, index;
  	struct inode *inode = context->inode;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct ocfs2_extent_rec *rec, replace_rec;
  	struct ocfs2_path *path = NULL;
  	struct ocfs2_extent_list *el;
  	u64 ino = ocfs2_metadata_cache_owner(context->et.et_ci);
  	u64 old_blkno = ocfs2_clusters_to_blocks(inode->i_sb, p_cpos);
  
  	ret = ocfs2_duplicate_clusters_by_page(handle, context->file, cpos,
  					       p_cpos, new_p_cpos, len);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	memset(&replace_rec, 0, sizeof(replace_rec));
  	replace_rec.e_cpos = cpu_to_le32(cpos);
  	replace_rec.e_leaf_clusters = cpu_to_le16(len);
  	replace_rec.e_blkno = cpu_to_le64(ocfs2_clusters_to_blocks(inode->i_sb,
  								   new_p_cpos));
  
  	path = ocfs2_new_path_from_et(&context->et);
  	if (!path) {
  		ret = -ENOMEM;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_find_path(INODE_CACHE(inode), path, cpos);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	el = path_leaf_el(path);
  
  	index = ocfs2_search_extent_list(el, cpos);
  	if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
  		ocfs2_error(inode->i_sb,
  			    "Inode %llu has an extent at cpos %u which can no "
  			    "longer be found.\n",
  			    (unsigned long long)ino, cpos);
  		ret = -EROFS;
  		goto out;
  	}
  
  	rec = &el->l_recs[index];
  
  	BUG_ON(ext_flags != rec->e_flags);
  	/*
  	 * after moving/defraging to new location, the extent is not going
  	 * to be refcounted anymore.
  	 */
  	replace_rec.e_flags = ext_flags & ~OCFS2_EXT_REFCOUNTED;
  
  	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode),
  				      context->et.et_root_bh,
  				      OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ret = ocfs2_split_extent(handle, &context->et, path, index,
  				 &replace_rec, context->meta_ac,
  				 &context->dealloc);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ocfs2_journal_dirty(handle, context->et.et_root_bh);
  
  	context->new_phys_cpos = new_p_cpos;
  
  	/*
  	 * need I to append truncate log for old clusters?
  	 */
  	if (old_blkno) {
  		if (ext_flags & OCFS2_EXT_REFCOUNTED)
  			ret = ocfs2_decrease_refcount(inode, handle,
  					ocfs2_blocks_to_clusters(osb->sb,
  								 old_blkno),
  					len, context->meta_ac,
  					&context->dealloc, 1);
  		else
  			ret = ocfs2_truncate_log_append(osb, handle,
  							old_blkno, len);
  	}
  
  out:
  	return ret;
  }
  
  /*
   * lock allocators, and reserving appropriate number of bits for
   * meta blocks and data clusters.
   *
   * in some cases, we don't need to reserve clusters, just let data_ac
   * be NULL.
   */
  static int ocfs2_lock_allocators_move_extents(struct inode *inode,
  					struct ocfs2_extent_tree *et,
  					u32 clusters_to_move,
  					u32 extents_to_split,
  					struct ocfs2_alloc_context **meta_ac,
  					struct ocfs2_alloc_context **data_ac,
  					int extra_blocks,
  					int *credits)
  {
  	int ret, num_free_extents;
  	unsigned int max_recs_needed = 2 * extents_to_split + clusters_to_move;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	num_free_extents = ocfs2_num_free_extents(osb, et);
  	if (num_free_extents < 0) {
  		ret = num_free_extents;
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (!num_free_extents ||
  	    (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed))
  		extra_blocks += ocfs2_extend_meta_needed(et->et_root_el);
  
  	ret = ocfs2_reserve_new_metadata_blocks(osb, extra_blocks, meta_ac);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	if (data_ac) {
  		ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el,
  					      clusters_to_move + 2);
  
  	mlog(0, "reserve metadata_blocks: %d, data_clusters: %u, credits: %d\n",
  	     extra_blocks, clusters_to_move, *credits);
  out:
  	if (ret) {
  		if (*meta_ac) {
  			ocfs2_free_alloc_context(*meta_ac);
  			*meta_ac = NULL;
  		}
  	}
  
  	return ret;
  }
  
  /*
   * Using one journal handle to guarantee the data consistency in case
   * crash happens anywhere.
   *
   *  XXX: defrag can end up with finishing partial extent as requested,
   * due to not enough contiguous clusters can be found in allocator.
   */
  static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
  			       u32 cpos, u32 phys_cpos, u32 *len, int ext_flags)
  {
  	int ret, credits = 0, extra_blocks = 0, partial = context->partial;
  	handle_t *handle;
  	struct inode *inode = context->inode;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct ocfs2_refcount_tree *ref_tree = NULL;
  	u32 new_phys_cpos, new_len;
  	u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
  
  	if ((ext_flags & OCFS2_EXT_REFCOUNTED) && *len) {
  
  		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
  			 OCFS2_HAS_REFCOUNT_FL));
  
  		BUG_ON(!context->refcount_loc);
  
  		ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
  					       &ref_tree, NULL);
  		if (ret) {
  			mlog_errno(ret);
  			return ret;
  		}
  
  		ret = ocfs2_prepare_refcount_change_for_del(inode,
  							context->refcount_loc,
  							phys_blkno,
  							*len,
  							&credits,
  							&extra_blocks);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
  						 &context->meta_ac,
  						 &context->data_ac,
  						 extra_blocks, &credits);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * should be using allocation reservation strategy there?
  	 *
  	 * if (context->data_ac)
  	 *	context->data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
  	 */
  
  	mutex_lock(&tl_inode->i_mutex);
  
  	if (ocfs2_truncate_log_needs_flush(osb)) {
  		ret = __ocfs2_flush_truncate_log(osb);
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out_unlock_mutex;
  		}
  	}
  
  	handle = ocfs2_start_trans(osb, credits);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out_unlock_mutex;
  	}
  
  	ret = __ocfs2_claim_clusters(handle, context->data_ac, 1, *len,
  				     &new_phys_cpos, &new_len);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	/*
  	 * allowing partial extent moving is kind of 'pros and cons', it makes
  	 * whole defragmentation less likely to fail, on the contrary, the bad
  	 * thing is it may make the fs even more fragmented after moving, let
  	 * userspace make a good decision here.
  	 */
  	if (new_len != *len) {
  		mlog(0, "len_claimed: %u, len: %u\n", new_len, *len);
  		if (!partial) {
  			context->range->me_flags &= ~OCFS2_MOVE_EXT_FL_COMPLETE;
  			ret = -ENOSPC;
  			goto out_commit;
  		}
  	}
  
  	mlog(0, "cpos: %u, phys_cpos: %u, new_phys_cpos: %u\n", cpos,
  	     phys_cpos, new_phys_cpos);
  
  	ret = __ocfs2_move_extent(handle, context, cpos, new_len, phys_cpos,
  				  new_phys_cpos, ext_flags);
  	if (ret)
  		mlog_errno(ret);
  
  	if (partial && (new_len != *len))
  		*len = new_len;
  
  	/*
  	 * Here we should write the new page out first if we are
  	 * in write-back mode.
  	 */
  	ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, *len);
  	if (ret)
  		mlog_errno(ret);
  
  out_commit:
  	ocfs2_commit_trans(osb, handle);
  
  out_unlock_mutex:
  	mutex_unlock(&tl_inode->i_mutex);
  
  	if (context->data_ac) {
  		ocfs2_free_alloc_context(context->data_ac);
  		context->data_ac = NULL;
  	}
  
  	if (context->meta_ac) {
  		ocfs2_free_alloc_context(context->meta_ac);
  		context->meta_ac = NULL;
  	}
  
  out:
  	if (ref_tree)
  		ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
  
  	return ret;
  }
  
  /*
   * find the victim alloc group, where #blkno fits.
   */
  static int ocfs2_find_victim_alloc_group(struct inode *inode,
  					 u64 vict_blkno,
  					 int type, int slot,
  					 int *vict_bit,
  					 struct buffer_head **ret_bh)
  {
  	int ret, i, bits_per_unit = 0;
  	u64 blkno;
  	char namebuf[40];
  
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct buffer_head *ac_bh = NULL, *gd_bh = NULL;
  	struct ocfs2_chain_list *cl;
  	struct ocfs2_chain_rec *rec;
  	struct ocfs2_dinode *ac_dinode;
  	struct ocfs2_group_desc *bg;
  
  	ocfs2_sprintf_system_inode_name(namebuf, sizeof(namebuf), type, slot);
  	ret = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
  					 strlen(namebuf), &blkno);
  	if (ret) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	ret = ocfs2_read_blocks_sync(osb, blkno, 1, &ac_bh);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	ac_dinode = (struct ocfs2_dinode *)ac_bh->b_data;
  	cl = &(ac_dinode->id2.i_chain);
  	rec = &(cl->cl_recs[0]);
  
  	if (type == GLOBAL_BITMAP_SYSTEM_INODE)
  		bits_per_unit = osb->s_clustersize_bits -
  					inode->i_sb->s_blocksize_bits;
  	/*
  	 * 'vict_blkno' was out of the valid range.
  	 */
  	if ((vict_blkno < le64_to_cpu(rec->c_blkno)) ||
  	    (vict_blkno >= (le32_to_cpu(ac_dinode->id1.bitmap1.i_total) <<
  				bits_per_unit))) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i++) {
  
  		rec = &(cl->cl_recs[i]);
  		if (!rec)
  			continue;
  
  		bg = NULL;
  
  		do {
  			if (!bg)
  				blkno = le64_to_cpu(rec->c_blkno);
  			else
  				blkno = le64_to_cpu(bg->bg_next_group);
  
  			if (gd_bh) {
  				brelse(gd_bh);
  				gd_bh = NULL;
  			}
  
  			ret = ocfs2_read_blocks_sync(osb, blkno, 1, &gd_bh);
  			if (ret) {
  				mlog_errno(ret);
  				goto out;
  			}
  
  			bg = (struct ocfs2_group_desc *)gd_bh->b_data;
  
  			if (vict_blkno < (le64_to_cpu(bg->bg_blkno) +
  						le16_to_cpu(bg->bg_bits))) {
  
  				*ret_bh = gd_bh;
  				*vict_bit = (vict_blkno - blkno) >>
  							bits_per_unit;
  				mlog(0, "find the victim group: #%llu, "
  				     "total_bits: %u, vict_bit: %u\n",
  				     blkno, le16_to_cpu(bg->bg_bits),
  				     *vict_bit);
  				goto out;
  			}
  
  		} while (le64_to_cpu(bg->bg_next_group));
  	}
  
  	ret = -EINVAL;
  out:
  	brelse(ac_bh);
  
  	/*
  	 * caller has to release the gd_bh properly.
  	 */
  	return ret;
  }
  
  /*
   * XXX: helper to validate and adjust moving goal.
   */
  static int ocfs2_validate_and_adjust_move_goal(struct inode *inode,
  					       struct ocfs2_move_extents *range)
  {
  	int ret, goal_bit = 0;
  
  	struct buffer_head *gd_bh = NULL;
  	struct ocfs2_group_desc *bg = NULL;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	int c_to_b = 1 << (osb->s_clustersize_bits -
  					inode->i_sb->s_blocksize_bits);
  
  	/*
  	 * make goal become cluster aligned.
  	 */
  	range->me_goal = ocfs2_block_to_cluster_start(inode->i_sb,
  						      range->me_goal);
  	/*
  	 * moving goal is not allowd to start with a group desc blok(#0 blk)
  	 * let's compromise to the latter cluster.
  	 */
  	if (range->me_goal == le64_to_cpu(bg->bg_blkno))
  		range->me_goal += c_to_b;
  
  	/*
  	 * validate goal sits within global_bitmap, and return the victim
  	 * group desc
  	 */
  	ret = ocfs2_find_victim_alloc_group(inode, range->me_goal,
  					    GLOBAL_BITMAP_SYSTEM_INODE,
  					    OCFS2_INVALID_SLOT,
  					    &goal_bit, &gd_bh);
  	if (ret)
  		goto out;
  
  	bg = (struct ocfs2_group_desc *)gd_bh->b_data;
  
  	/*
  	 * movement is not gonna cross two groups.
  	 */
  	if ((le16_to_cpu(bg->bg_bits) - goal_bit) * osb->s_clustersize <
  								range->me_len) {
  		ret = -EINVAL;
  		goto out;
  	}
  	/*
  	 * more exact validations/adjustments will be performed later during
  	 * moving operation for each extent range.
  	 */
  	mlog(0, "extents get ready to be moved to #%llu block\n",
  	     range->me_goal);
  
  out:
  	brelse(gd_bh);
  
  	return ret;
  }
  
  static void ocfs2_probe_alloc_group(struct inode *inode, struct buffer_head *bh,
  				    int *goal_bit, u32 move_len, u32 max_hop,
  				    u32 *phys_cpos)
  {
  	int i, used, last_free_bits = 0, base_bit = *goal_bit;
  	struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
  	u32 base_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
  						 le64_to_cpu(gd->bg_blkno));
  
  	for (i = base_bit; i < le16_to_cpu(gd->bg_bits); i++) {
  
  		used = ocfs2_test_bit(i, (unsigned long *)gd->bg_bitmap);
  		if (used) {
  			/*
  			 * we even tried searching the free chunk by jumping
  			 * a 'max_hop' distance, but still failed.
  			 */
  			if ((i - base_bit) > max_hop) {
  				*phys_cpos = 0;
  				break;
  			}
  
  			if (last_free_bits)
  				last_free_bits = 0;
  
  			continue;
  		} else
  			last_free_bits++;
  
  		if (last_free_bits == move_len) {
  			*goal_bit = i;
  			*phys_cpos = base_cpos + i;
  			break;
  		}
  	}
  
  	mlog(0, "found phys_cpos: %u to fit the wanted moving.\n", *phys_cpos);
  }
  
  static int ocfs2_alloc_dinode_update_counts(struct inode *inode,
  				       handle_t *handle,
  				       struct buffer_head *di_bh,
  				       u32 num_bits,
  				       u16 chain)
  {
  	int ret;
  	u32 tmp_used;
  	struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
  	struct ocfs2_chain_list *cl =
  				(struct ocfs2_chain_list *) &di->id2.i_chain;
  
  	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
  				      OCFS2_JOURNAL_ACCESS_WRITE);
  	if (ret < 0) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
  	di->id1.bitmap1.i_used = cpu_to_le32(num_bits + tmp_used);
  	le32_add_cpu(&cl->cl_recs[chain].c_free, -num_bits);
  	ocfs2_journal_dirty(handle, di_bh);
  
  out:
  	return ret;
  }
  
  static inline int ocfs2_block_group_set_bits(handle_t *handle,
  					     struct inode *alloc_inode,
  					     struct ocfs2_group_desc *bg,
  					     struct buffer_head *group_bh,
  					     unsigned int bit_off,
  					     unsigned int num_bits)
  {
  	int status;
  	void *bitmap = bg->bg_bitmap;
  	int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
  
  	/* All callers get the descriptor via
  	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
  	BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
  	BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);
  
  	mlog(0, "block_group_set_bits: off = %u, num = %u\n", bit_off,
  	     num_bits);
  
  	if (ocfs2_is_cluster_bitmap(alloc_inode))
  		journal_type = OCFS2_JOURNAL_ACCESS_UNDO;
  
  	status = ocfs2_journal_access_gd(handle,
  					 INODE_CACHE(alloc_inode),
  					 group_bh,
  					 journal_type);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	le16_add_cpu(&bg->bg_free_bits_count, -num_bits);
  	if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
  		ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
  			    " count %u but claims %u are freed. num_bits %d",
  			    (unsigned long long)le64_to_cpu(bg->bg_blkno),
  			    le16_to_cpu(bg->bg_bits),
  			    le16_to_cpu(bg->bg_free_bits_count), num_bits);
  		return -EROFS;
  	}
  	while (num_bits--)
  		ocfs2_set_bit(bit_off++, bitmap);
  
  	ocfs2_journal_dirty(handle, group_bh);
  
  bail:
  	return status;
  }
  
  static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
  			     u32 cpos, u32 phys_cpos, u32 *new_phys_cpos,
  			     u32 len, int ext_flags)
  {
  	int ret, credits = 0, extra_blocks = 0, goal_bit = 0;
  	handle_t *handle;
  	struct inode *inode = context->inode;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  	struct inode *tl_inode = osb->osb_tl_inode;
  	struct inode *gb_inode = NULL;
  	struct buffer_head *gb_bh = NULL;
  	struct buffer_head *gd_bh = NULL;
  	struct ocfs2_group_desc *gd;
  	struct ocfs2_refcount_tree *ref_tree = NULL;
  	u32 move_max_hop = ocfs2_blocks_to_clusters(inode->i_sb,
  						    context->range->me_threshold);
  	u64 phys_blkno, new_phys_blkno;
  
  	phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
  
  	if ((ext_flags & OCFS2_EXT_REFCOUNTED) && len) {
  
  		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
  			 OCFS2_HAS_REFCOUNT_FL));
  
  		BUG_ON(!context->refcount_loc);
  
  		ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
  					       &ref_tree, NULL);
  		if (ret) {
  			mlog_errno(ret);
  			return ret;
  		}
  
  		ret = ocfs2_prepare_refcount_change_for_del(inode,
  							context->refcount_loc,
  							phys_blkno,
  							len,
  							&credits,
  							&extra_blocks);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  	}
  
  	ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
  						 &context->meta_ac,
  						 NULL, extra_blocks, &credits);
  	if (ret) {
  		mlog_errno(ret);
  		goto out;
  	}
  
  	/*
  	 * need to count 2 extra credits for global_bitmap inode and
  	 * group descriptor.
  	 */
  	credits += OCFS2_INODE_UPDATE_CREDITS + 1;
  
  	/*
  	 * ocfs2_move_extent() didn't reserve any clusters in lock_allocators()
  	 * logic, while we still need to lock the global_bitmap.
  	 */
  	gb_inode = ocfs2_get_system_file_inode(osb, GLOBAL_BITMAP_SYSTEM_INODE,
  					       OCFS2_INVALID_SLOT);
  	if (!gb_inode) {
  		mlog(ML_ERROR, "unable to get global_bitmap inode\n");
  		ret = -EIO;
  		goto out;
  	}
  
  	mutex_lock(&gb_inode->i_mutex);
  
  	ret = ocfs2_inode_lock(gb_inode, &gb_bh, 1);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_unlock_gb_mutex;
  	}
  
  	mutex_lock(&tl_inode->i_mutex);
  
  	handle = ocfs2_start_trans(osb, credits);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		mlog_errno(ret);
  		goto out_unlock_tl_inode;
  	}
  
  	new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
  	ret = ocfs2_find_victim_alloc_group(inode, new_phys_blkno,
  					    GLOBAL_BITMAP_SYSTEM_INODE,
  					    OCFS2_INVALID_SLOT,
  					    &goal_bit, &gd_bh);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	/*
  	 * probe the victim cluster group to find a proper
  	 * region to fit wanted movement, it even will perfrom
  	 * a best-effort attempt by compromising to a threshold
  	 * around the goal.
  	 */
  	ocfs2_probe_alloc_group(inode, gd_bh, &goal_bit, len, move_max_hop,
  				new_phys_cpos);
  	if (!new_phys_cpos) {
  		ret = -ENOSPC;
  		goto out_commit;
  	}
  
  	ret = __ocfs2_move_extent(handle, context, cpos, len, phys_cpos,
  				  *new_phys_cpos, ext_flags);
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	gd = (struct ocfs2_group_desc *)gd_bh->b_data;
  	ret = ocfs2_alloc_dinode_update_counts(gb_inode, handle, gb_bh, len,
  					       le16_to_cpu(gd->bg_chain));
  	if (ret) {
  		mlog_errno(ret);
  		goto out_commit;
  	}
  
  	ret = ocfs2_block_group_set_bits(handle, gb_inode, gd, gd_bh,
  					 goal_bit, len);
  	if (ret)
  		mlog_errno(ret);
  
  	/*
  	 * Here we should write the new page out first if we are
  	 * in write-back mode.
  	 */
  	ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, len);
  	if (ret)
  		mlog_errno(ret);
  
  out_commit:
  	ocfs2_commit_trans(osb, handle);
  	brelse(gd_bh);
  
  out_unlock_tl_inode:
  	mutex_unlock(&tl_inode->i_mutex);
  
  	ocfs2_inode_unlock(gb_inode, 1);
  out_unlock_gb_mutex:
  	mutex_unlock(&gb_inode->i_mutex);
  	brelse(gb_bh);
  	iput(gb_inode);
  
  out:
  	if (context->meta_ac) {
  		ocfs2_free_alloc_context(context->meta_ac);
  		context->meta_ac = NULL;
  	}
  
  	if (ref_tree)
  		ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
  
  	return ret;
  }
  
  /*
   * Helper to calculate the defraging length in one run according to threshold.
   */
  static void ocfs2_calc_extent_defrag_len(u32 *alloc_size, u32 *len_defraged,
  					 u32 threshold, int *skip)
  {
  	if ((*alloc_size + *len_defraged) < threshold) {
  		/*
  		 * proceed defragmentation until we meet the thresh
  		 */
  		*len_defraged += *alloc_size;
  	} else if (*len_defraged == 0) {
  		/*
  		 * XXX: skip a large extent.
  		 */
  		*skip = 1;
  	} else {
  		/*
  		 * split this extent to coalesce with former pieces as
  		 * to reach the threshold.
  		 *
  		 * we're done here with one cycle of defragmentation
  		 * in a size of 'thresh', resetting 'len_defraged'
  		 * forces a new defragmentation.
  		 */
  		*alloc_size = threshold - *len_defraged;
  		*len_defraged = 0;
  	}
  }
  
  static int __ocfs2_move_extents_range(struct buffer_head *di_bh,
  				struct ocfs2_move_extents_context *context)
  {
  	int ret = 0, flags, do_defrag, skip = 0;
  	u32 cpos, phys_cpos, move_start, len_to_move, alloc_size;
  	u32 len_defraged = 0, defrag_thresh = 0, new_phys_cpos = 0;
  
  	struct inode *inode = context->inode;
  	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
  	struct ocfs2_move_extents *range = context->range;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	if ((inode->i_size == 0) || (range->me_len == 0))
  		return 0;
  
  	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
  		return 0;
  
  	context->refcount_loc = le64_to_cpu(di->i_refcount_loc);
  
  	ocfs2_init_dinode_extent_tree(&context->et, INODE_CACHE(inode), di_bh);
  	ocfs2_init_dealloc_ctxt(&context->dealloc);
  
  	/*
  	 * TO-DO XXX:
  	 *
  	 * - xattr extents.
  	 */
  
  	do_defrag = context->auto_defrag;
  
  	/*
  	 * extents moving happens in unit of clusters, for the sake
  	 * of simplicity, we may ignore two clusters where 'byte_start'
  	 * and 'byte_start + len' were within.
  	 */
  	move_start = ocfs2_clusters_for_bytes(osb->sb, range->me_start);
  	len_to_move = (range->me_start + range->me_len) >>
  						osb->s_clustersize_bits;
  	if (len_to_move >= move_start)
  		len_to_move -= move_start;
  	else
  		len_to_move = 0;
  
  	if (do_defrag) {
  		defrag_thresh = range->me_threshold >> osb->s_clustersize_bits;
  		if (defrag_thresh <= 1)
  			goto done;
  	} else
  		new_phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
  							 range->me_goal);
  
  	mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: %u, "
  	     "thresh: %u\n",
  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
  	     (unsigned long long)range->me_start,
  	     (unsigned long long)range->me_len,
  	     move_start, len_to_move, defrag_thresh);
  
  	cpos = move_start;
  	while (len_to_move) {
  		ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &alloc_size,
  					 &flags);
  		if (ret) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		if (alloc_size > len_to_move)
  			alloc_size = len_to_move;
  
  		/*
  		 * XXX: how to deal with a hole:
  		 *
  		 * - skip the hole of course
  		 * - force a new defragmentation
  		 */
  		if (!phys_cpos) {
  			if (do_defrag)
  				len_defraged = 0;
  
  			goto next;
  		}
  
  		if (do_defrag) {
  			ocfs2_calc_extent_defrag_len(&alloc_size, &len_defraged,
  						     defrag_thresh, &skip);
  			/*
  			 * skip large extents
  			 */
  			if (skip) {
  				skip = 0;
  				goto next;
  			}
  
  			mlog(0, "#Defrag: cpos: %u, phys_cpos: %u, "
  			     "alloc_size: %u, len_defraged: %u\n",
  			     cpos, phys_cpos, alloc_size, len_defraged);
  
  			ret = ocfs2_defrag_extent(context, cpos, phys_cpos,
  						  &alloc_size, flags);
  		} else {
  			ret = ocfs2_move_extent(context, cpos, phys_cpos,
  						&new_phys_cpos, alloc_size,
  						flags);
  
  			new_phys_cpos += alloc_size;
  		}
  
  		if (ret < 0) {
  			mlog_errno(ret);
  			goto out;
  		}
  
  		context->clusters_moved += alloc_size;
  next:
  		cpos += alloc_size;
  		len_to_move -= alloc_size;
  	}
  
  done:
  	range->me_flags |= OCFS2_MOVE_EXT_FL_COMPLETE;
  
  out:
  	range->me_moved_len = ocfs2_clusters_to_bytes(osb->sb,
  						      context->clusters_moved);
  	range->me_new_offset = ocfs2_clusters_to_bytes(osb->sb,
  						       context->new_phys_cpos);
  
  	ocfs2_schedule_truncate_log_flush(osb, 1);
  	ocfs2_run_deallocs(osb, &context->dealloc);
  
  	return ret;
  }
  
  static int ocfs2_move_extents(struct ocfs2_move_extents_context *context)
  {
  	int status;
  	handle_t *handle;
  	struct inode *inode = context->inode;
  	struct ocfs2_dinode *di;
  	struct buffer_head *di_bh = NULL;
  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
  
  	if (!inode)
  		return -ENOENT;
  
  	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
  		return -EROFS;
  
  	mutex_lock(&inode->i_mutex);
  
  	/*
  	 * This prevents concurrent writes from other nodes
  	 */
  	status = ocfs2_rw_lock(inode, 1);
  	if (status) {
  		mlog_errno(status);
  		goto out;
  	}
  
  	status = ocfs2_inode_lock(inode, &di_bh, 1);
  	if (status) {
  		mlog_errno(status);
  		goto out_rw_unlock;
  	}
  
  	/*
  	 * rememer ip_xattr_sem also needs to be held if necessary
  	 */
  	down_write(&OCFS2_I(inode)->ip_alloc_sem);
  
  	status = __ocfs2_move_extents_range(di_bh, context);
  
  	up_write(&OCFS2_I(inode)->ip_alloc_sem);
  	if (status) {
  		mlog_errno(status);
  		goto out_inode_unlock;
  	}
  
  	/*
  	 * We update ctime for these changes
  	 */
  	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
  	if (IS_ERR(handle)) {
  		status = PTR_ERR(handle);
  		mlog_errno(status);
  		goto out_inode_unlock;
  	}
  
  	status = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
  					 OCFS2_JOURNAL_ACCESS_WRITE);
  	if (status) {
  		mlog_errno(status);
  		goto out_commit;
  	}
  
  	di = (struct ocfs2_dinode *)di_bh->b_data;
  	inode->i_ctime = CURRENT_TIME;
  	di->i_ctime = cpu_to_le64(inode->i_ctime.tv_sec);
  	di->i_ctime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
  
  	ocfs2_journal_dirty(handle, di_bh);
  
  out_commit:
  	ocfs2_commit_trans(osb, handle);
  
  out_inode_unlock:
  	brelse(di_bh);
  	ocfs2_inode_unlock(inode, 1);
  out_rw_unlock:
  	ocfs2_rw_unlock(inode, 1);
  out:
  	mutex_unlock(&inode->i_mutex);
  
  	return status;
  }
  
  int ocfs2_ioctl_move_extents(struct file *filp, void __user *argp)
  {
  	int status;
  
  	struct inode *inode = filp->f_path.dentry->d_inode;
  	struct ocfs2_move_extents range;
  	struct ocfs2_move_extents_context *context = NULL;
  
  	status = mnt_want_write(filp->f_path.mnt);
  	if (status)
  		return status;
  
  	if ((!S_ISREG(inode->i_mode)) || !(filp->f_mode & FMODE_WRITE))
  		goto out;
  
  	if (inode->i_flags & (S_IMMUTABLE|S_APPEND)) {
  		status = -EPERM;
  		goto out;
  	}
  
  	context = kzalloc(sizeof(struct ocfs2_move_extents_context), GFP_NOFS);
  	if (!context) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto out;
  	}
  
  	context->inode = inode;
  	context->file = filp;
  
  	if (argp) {
  		if (copy_from_user(&range, (struct ocfs2_move_extents *)argp,
  				   sizeof(range))) {
  			status = -EFAULT;
  			goto out;
  		}
  	} else {
  		status = -EINVAL;
  		goto out;
  	}
  
  	if (range.me_start > i_size_read(inode))
  		goto out;
  
  	if (range.me_start + range.me_len > i_size_read(inode))
  			range.me_len = i_size_read(inode) - range.me_start;
  
  	context->range = &range;
  
  	if (range.me_flags & OCFS2_MOVE_EXT_FL_AUTO_DEFRAG) {
  		context->auto_defrag = 1;
  		/*
  		 * ok, the default theshold for the defragmentation
  		 * is 1M, since our maximum clustersize was 1M also.
  		 * any thought?
  		 */
  		if (!range.me_threshold)
  			range.me_threshold = 1024 * 1024;
  
  		if (range.me_threshold > i_size_read(inode))
  			range.me_threshold = i_size_read(inode);
  
  		if (range.me_flags & OCFS2_MOVE_EXT_FL_PART_DEFRAG)
  			context->partial = 1;
  	} else {
  		/*
  		 * first best-effort attempt to validate and adjust the goal
  		 * (physical address in block), while it can't guarantee later
  		 * operation can succeed all the time since global_bitmap may
  		 * change a bit over time.
  		 */
  
  		status = ocfs2_validate_and_adjust_move_goal(inode, &range);
  		if (status)
  			goto out;
  	}
  
  	status = ocfs2_move_extents(context);
  	if (status)
  		mlog_errno(status);
  out:
  	/*
  	 * movement/defragmentation may end up being partially completed,
  	 * that's the reason why we need to return userspace the finished
  	 * length and new_offset even if failure happens somewhere.
  	 */
  	if (argp) {
  		if (copy_to_user((struct ocfs2_move_extents *)argp, &range,
  				sizeof(range)))
  			status = -EFAULT;
  	}
  
  	kfree(context);
  
  	mnt_drop_write(filp->f_path.mnt);
  
  	return status;
  }
  