/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * localalloc.c
   *
   * Node local data allocation
   *
   * Copyright (C) 2002, 2004 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 as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * 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.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/fs.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/bitops.h>

  #include <cluster/masklog.h>
  
  #include "ocfs2.h"
  
  #include "alloc.h"

  #include "blockcheck.h"

  #include "dlmglue.h"
  #include "inode.h"
  #include "journal.h"
  #include "localalloc.h"
  #include "suballoc.h"
  #include "super.h"
  #include "sysfile.h"

  #include "ocfs2_trace.h"

  
  #include "buffer_head_io.h"
  
  #define OCFS2_LOCAL_ALLOC(dinode)	(&((dinode)->id2.i_lab))

  static u32 ocfs2_local_alloc_count_bits(struct ocfs2_dinode *alloc);
  
  static int ocfs2_local_alloc_find_clear_bits(struct ocfs2_super *osb,
  					     struct ocfs2_dinode *alloc,

  					     u32 *numbits,
  					     struct ocfs2_alloc_reservation *resv);

  
  static void ocfs2_clear_local_alloc(struct ocfs2_dinode *alloc);
  
  static int ocfs2_sync_local_to_main(struct ocfs2_super *osb,

  				    handle_t *handle,

  				    struct ocfs2_dinode *alloc,
  				    struct inode *main_bm_inode,
  				    struct buffer_head *main_bm_bh);
  
  static int ocfs2_local_alloc_reserve_for_window(struct ocfs2_super *osb,

  						struct ocfs2_alloc_context **ac,
  						struct inode **bitmap_inode,
  						struct buffer_head **bitmap_bh);
  
  static int ocfs2_local_alloc_new_window(struct ocfs2_super *osb,

  					handle_t *handle,

  					struct ocfs2_alloc_context *ac);
  
  static int ocfs2_local_alloc_slide_window(struct ocfs2_super *osb,
  					  struct inode *local_alloc_inode);

  /*
   * ocfs2_la_default_mb() - determine a default size, in megabytes of
   * the local alloc.
   *
   * Generally, we'd like to pick as large a local alloc as
   * possible. Performance on large workloads tends to scale
   * proportionally to la size. In addition to that, the reservations
   * code functions more efficiently as it can reserve more windows for
   * write.
   *
   * Some things work against us when trying to choose a large local alloc:
   *
   * - We need to ensure our sizing is picked to leave enough space in
   *   group descriptors for other allocations (such as block groups,
   *   etc). Picking default sizes which are a multiple of 4 could help
   *   - block groups are allocated in 2mb and 4mb chunks.
   *
   * - Likewise, we don't want to starve other nodes of bits on small
   *   file systems. This can easily be taken care of by limiting our
   *   default to a reasonable size (256M) on larger cluster sizes.
   *
   * - Some file systems can't support very large sizes - 4k and 8k in
   *   particular are limited to less than 128 and 256 megabytes respectively.
   *
   * The following reference table shows group descriptor and local
   * alloc maximums at various cluster sizes (4k blocksize)
   *
   * csize: 4K	group: 126M	la: 121M
   * csize: 8K	group: 252M	la: 243M
   * csize: 16K	group: 504M	la: 486M
   * csize: 32K	group: 1008M	la: 972M
   * csize: 64K	group: 2016M	la: 1944M
   * csize: 128K	group: 4032M	la: 3888M
   * csize: 256K	group: 8064M	la: 7776M
   * csize: 512K	group: 16128M	la: 15552M
   * csize: 1024K	group: 32256M	la: 31104M
   */
  #define	OCFS2_LA_MAX_DEFAULT_MB	256
  #define	OCFS2_LA_OLD_DEFAULT	8
  unsigned int ocfs2_la_default_mb(struct ocfs2_super *osb)
  {
  	unsigned int la_mb;
  	unsigned int gd_mb;

  	unsigned int la_max_mb;

  	unsigned int megs_per_slot;
  	struct super_block *sb = osb->sb;
  
  	gd_mb = ocfs2_clusters_to_megabytes(osb->sb,

  		8 * ocfs2_group_bitmap_size(sb, 0, osb->s_feature_incompat));

  
  	/*
  	 * This takes care of files systems with very small group
  	 * descriptors - 512 byte blocksize at cluster sizes lower
  	 * than 16K and also 1k blocksize with 4k cluster size.
  	 */
  	if ((sb->s_blocksize == 512 && osb->s_clustersize <= 8192)
  	    || (sb->s_blocksize == 1024 && osb->s_clustersize == 4096))
  		return OCFS2_LA_OLD_DEFAULT;
  
  	/*
  	 * Leave enough room for some block groups and make the final
  	 * value we work from a multiple of 4.
  	 */
  	gd_mb -= 16;
  	gd_mb &= 0xFFFFFFFB;
  
  	la_mb = gd_mb;
  
  	/*
  	 * Keep window sizes down to a reasonable default
  	 */
  	if (la_mb > OCFS2_LA_MAX_DEFAULT_MB) {
  		/*
  		 * Some clustersize / blocksize combinations will have
  		 * given us a larger than OCFS2_LA_MAX_DEFAULT_MB
  		 * default size, but get poor distribution when
  		 * limited to exactly 256 megabytes.
  		 *
  		 * As an example, 16K clustersize at 4K blocksize
  		 * gives us a cluster group size of 504M. Paring the
  		 * local alloc size down to 256 however, would give us
  		 * only one window and around 200MB left in the
  		 * cluster group. Instead, find the first size below
  		 * 256 which would give us an even distribution.
  		 *
  		 * Larger cluster group sizes actually work out pretty
  		 * well when pared to 256, so we don't have to do this
  		 * for any group that fits more than two
  		 * OCFS2_LA_MAX_DEFAULT_MB windows.
  		 */
  		if (gd_mb > (2 * OCFS2_LA_MAX_DEFAULT_MB))
  			la_mb = 256;
  		else {
  			unsigned int gd_mult = gd_mb;
  
  			while (gd_mult > 256)
  				gd_mult = gd_mult >> 1;
  
  			la_mb = gd_mult;
  		}
  	}
  
  	megs_per_slot = osb->osb_clusters_at_boot / osb->max_slots;
  	megs_per_slot = ocfs2_clusters_to_megabytes(osb->sb, megs_per_slot);
  	/* Too many nodes, too few disk clusters. */
  	if (megs_per_slot < la_mb)
  		la_mb = megs_per_slot;

  	/* We can't store more bits than we can in a block. */
  	la_max_mb = ocfs2_clusters_to_megabytes(osb->sb,
  						ocfs2_local_alloc_size(sb) * 8);
  	if (la_mb > la_max_mb)
  		la_mb = la_max_mb;

  	return la_mb;
  }

  void ocfs2_la_set_sizes(struct ocfs2_super *osb, int requested_mb)
  {
  	struct super_block *sb = osb->sb;

  	unsigned int la_default_mb = ocfs2_la_default_mb(osb);

  	unsigned int la_max_mb;
  
  	la_max_mb = ocfs2_clusters_to_megabytes(sb,
  						ocfs2_local_alloc_size(sb) * 8);

  	trace_ocfs2_la_set_sizes(requested_mb, la_max_mb, la_default_mb);

  
  	if (requested_mb == -1) {
  		/* No user request - use defaults */
  		osb->local_alloc_default_bits =
  			ocfs2_megabytes_to_clusters(sb, la_default_mb);
  	} else if (requested_mb > la_max_mb) {
  		/* Request is too big, we give the maximum available */
  		osb->local_alloc_default_bits =
  			ocfs2_megabytes_to_clusters(sb, la_max_mb);
  	} else {
  		osb->local_alloc_default_bits =
  			ocfs2_megabytes_to_clusters(sb, requested_mb);
  	}
  
  	osb->local_alloc_bits = osb->local_alloc_default_bits;
  }

  static inline int ocfs2_la_state_enabled(struct ocfs2_super *osb)
  {
  	return (osb->local_alloc_state == OCFS2_LA_THROTTLED ||
  		osb->local_alloc_state == OCFS2_LA_ENABLED);
  }
  
  void ocfs2_local_alloc_seen_free_bits(struct ocfs2_super *osb,
  				      unsigned int num_clusters)
  {
  	spin_lock(&osb->osb_lock);
  	if (osb->local_alloc_state == OCFS2_LA_DISABLED ||
  	    osb->local_alloc_state == OCFS2_LA_THROTTLED)
  		if (num_clusters >= osb->local_alloc_default_bits) {
  			cancel_delayed_work(&osb->la_enable_wq);
  			osb->local_alloc_state = OCFS2_LA_ENABLED;
  		}
  	spin_unlock(&osb->osb_lock);
  }
  
  void ocfs2_la_enable_worker(struct work_struct *work)
  {
  	struct ocfs2_super *osb =
  		container_of(work, struct ocfs2_super,
  			     la_enable_wq.work);
  	spin_lock(&osb->osb_lock);
  	osb->local_alloc_state = OCFS2_LA_ENABLED;
  	spin_unlock(&osb->osb_lock);
  }

  /*
   * Tell us whether a given allocation should use the local alloc
   * file. Otherwise, it has to go to the main bitmap.

   *
   * This function does semi-dirty reads of local alloc size and state!
   * This is ok however, as the values are re-checked once under mutex.

   */
  int ocfs2_alloc_should_use_local(struct ocfs2_super *osb, u64 bits)
  {

  	int ret = 0;

  	int la_bits;
  
  	spin_lock(&osb->osb_lock);
  	la_bits = osb->local_alloc_bits;

  	if (!ocfs2_la_state_enabled(osb))

  		goto bail;

  
  	/* la_bits should be at least twice the size (in clusters) of
  	 * a new block group. We want to be sure block group
  	 * allocations go through the local alloc, so allow an
  	 * allocation to take up to half the bitmap. */
  	if (bits > (la_bits / 2))

  		goto bail;

  	ret = 1;
  bail:

  	trace_ocfs2_alloc_should_use_local(
  	     (unsigned long long)bits, osb->local_alloc_state, la_bits, ret);

  	spin_unlock(&osb->osb_lock);

  	return ret;

  }
  
  int ocfs2_load_local_alloc(struct ocfs2_super *osb)
  {
  	int status = 0;
  	struct ocfs2_dinode *alloc = NULL;
  	struct buffer_head *alloc_bh = NULL;
  	u32 num_used;
  	struct inode *inode = NULL;
  	struct ocfs2_local_alloc *la;

  	if (osb->local_alloc_bits == 0)

  		goto bail;

  	if (osb->local_alloc_bits >= osb->bitmap_cpg) {

  		mlog(ML_NOTICE, "Requested local alloc window %d is larger "
  		     "than max possible %u. Using defaults.
  ",

  		     osb->local_alloc_bits, (osb->bitmap_cpg - 1));
  		osb->local_alloc_bits =
  			ocfs2_megabytes_to_clusters(osb->sb,

  						    ocfs2_la_default_mb(osb));

  	}

  	/* read the alloc off disk */
  	inode = ocfs2_get_system_file_inode(osb, LOCAL_ALLOC_SYSTEM_INODE,
  					    osb->slot_num);
  	if (!inode) {
  		status = -EINVAL;
  		mlog_errno(status);
  		goto bail;
  	}

  	status = ocfs2_read_inode_block_full(inode, &alloc_bh,
  					     OCFS2_BH_IGNORE_CACHE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	alloc = (struct ocfs2_dinode *) alloc_bh->b_data;
  	la = OCFS2_LOCAL_ALLOC(alloc);
  
  	if (!(le32_to_cpu(alloc->i_flags) &
  	    (OCFS2_LOCAL_ALLOC_FL|OCFS2_BITMAP_FL))) {

  		mlog(ML_ERROR, "Invalid local alloc inode, %llu
  ",
  		     (unsigned long long)OCFS2_I(inode)->ip_blkno);

  		status = -EINVAL;
  		goto bail;
  	}
  
  	if ((la->la_size == 0) ||
  	    (le16_to_cpu(la->la_size) > ocfs2_local_alloc_size(inode->i_sb))) {
  		mlog(ML_ERROR, "Local alloc size is invalid (la_size = %u)
  ",
  		     le16_to_cpu(la->la_size));
  		status = -EINVAL;
  		goto bail;
  	}
  
  	/* do a little verification. */
  	num_used = ocfs2_local_alloc_count_bits(alloc);
  
  	/* hopefully the local alloc has always been recovered before
  	 * we load it. */
  	if (num_used
  	    || alloc->id1.bitmap1.i_used
  	    || alloc->id1.bitmap1.i_total
  	    || la->la_bm_off)
  		mlog(ML_ERROR, "Local alloc hasn't been recovered!
  "
  		     "found = %u, set = %u, taken = %u, off = %u
  ",
  		     num_used, le32_to_cpu(alloc->id1.bitmap1.i_used),
  		     le32_to_cpu(alloc->id1.bitmap1.i_total),
  		     OCFS2_LOCAL_ALLOC(alloc)->la_bm_off);
  
  	osb->local_alloc_bh = alloc_bh;
  	osb->local_alloc_state = OCFS2_LA_ENABLED;
  
  bail:
  	if (status < 0)

  		brelse(alloc_bh);

  	if (inode)
  		iput(inode);

  	trace_ocfs2_load_local_alloc(osb->local_alloc_bits);

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  /*
   * return any unused bits to the bitmap and write out a clean
   * local_alloc.
   *
   * local_alloc_bh is optional. If not passed, we will simply use the
   * one off osb. If you do pass it however, be warned that it *will* be
   * returned brelse'd and NULL'd out.*/
  void ocfs2_shutdown_local_alloc(struct ocfs2_super *osb)
  {
  	int status;

  	handle_t *handle;

  	struct inode *local_alloc_inode = NULL;
  	struct buffer_head *bh = NULL;
  	struct buffer_head *main_bm_bh = NULL;
  	struct inode *main_bm_inode = NULL;
  	struct ocfs2_dinode *alloc_copy = NULL;
  	struct ocfs2_dinode *alloc = NULL;

  	cancel_delayed_work(&osb->la_enable_wq);
  	flush_workqueue(ocfs2_wq);

  	if (osb->local_alloc_state == OCFS2_LA_UNUSED)

  		goto out;

  
  	local_alloc_inode =
  		ocfs2_get_system_file_inode(osb,
  					    LOCAL_ALLOC_SYSTEM_INODE,
  					    osb->slot_num);
  	if (!local_alloc_inode) {
  		status = -ENOENT;
  		mlog_errno(status);

  		goto out;

  	}
  
  	osb->local_alloc_state = OCFS2_LA_DISABLED;

  	ocfs2_resmap_uninit(&osb->osb_la_resmap);

  	main_bm_inode = ocfs2_get_system_file_inode(osb,
  						    GLOBAL_BITMAP_SYSTEM_INODE,
  						    OCFS2_INVALID_SLOT);
  	if (!main_bm_inode) {
  		status = -EINVAL;
  		mlog_errno(status);

  		goto out;

  	}

  	mutex_lock(&main_bm_inode->i_mutex);

  	status = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 1);

  	if (status < 0) {
  		mlog_errno(status);

  		goto out_mutex;

  	}
  
  	/* WINDOW_MOVE_CREDITS is a bit heavy... */

  	handle = ocfs2_start_trans(osb, OCFS2_WINDOW_MOVE_CREDITS);

  	if (IS_ERR(handle)) {
  		mlog_errno(PTR_ERR(handle));
  		handle = NULL;

  		goto out_unlock;

  	}
  
  	bh = osb->local_alloc_bh;
  	alloc = (struct ocfs2_dinode *) bh->b_data;

  	alloc_copy = kmalloc(bh->b_size, GFP_NOFS);

  	if (!alloc_copy) {
  		status = -ENOMEM;

  		goto out_commit;

  	}
  	memcpy(alloc_copy, alloc, bh->b_size);

  	status = ocfs2_journal_access_di(handle, INODE_CACHE(local_alloc_inode),
  					 bh, OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);

  		goto out_commit;

  	}
  
  	ocfs2_clear_local_alloc(alloc);

  	ocfs2_journal_dirty(handle, bh);

  
  	brelse(bh);
  	osb->local_alloc_bh = NULL;
  	osb->local_alloc_state = OCFS2_LA_UNUSED;
  
  	status = ocfs2_sync_local_to_main(osb, handle, alloc_copy,
  					  main_bm_inode, main_bm_bh);
  	if (status < 0)
  		mlog_errno(status);

  out_commit:

  	ocfs2_commit_trans(osb, handle);

  out_unlock:

  	brelse(main_bm_bh);

  	ocfs2_inode_unlock(main_bm_inode, 1);

  out_mutex:
  	mutex_unlock(&main_bm_inode->i_mutex);
  	iput(main_bm_inode);
  
  out:

  	if (local_alloc_inode)
  		iput(local_alloc_inode);
  
  	if (alloc_copy)
  		kfree(alloc_copy);

  }
  
  /*
   * We want to free the bitmap bits outside of any recovery context as
   * we'll need a cluster lock to do so, but we must clear the local
   * alloc before giving up the recovered nodes journal. To solve this,
   * we kmalloc a copy of the local alloc before it's change for the
   * caller to process with ocfs2_complete_local_alloc_recovery
   */
  int ocfs2_begin_local_alloc_recovery(struct ocfs2_super *osb,
  				     int slot_num,
  				     struct ocfs2_dinode **alloc_copy)
  {
  	int status = 0;
  	struct buffer_head *alloc_bh = NULL;
  	struct inode *inode = NULL;
  	struct ocfs2_dinode *alloc;

  	trace_ocfs2_begin_local_alloc_recovery(slot_num);

  
  	*alloc_copy = NULL;
  
  	inode = ocfs2_get_system_file_inode(osb,
  					    LOCAL_ALLOC_SYSTEM_INODE,
  					    slot_num);
  	if (!inode) {
  		status = -EINVAL;
  		mlog_errno(status);
  		goto bail;
  	}

  	mutex_lock(&inode->i_mutex);

  	status = ocfs2_read_inode_block_full(inode, &alloc_bh,
  					     OCFS2_BH_IGNORE_CACHE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	*alloc_copy = kmalloc(alloc_bh->b_size, GFP_KERNEL);
  	if (!(*alloc_copy)) {
  		status = -ENOMEM;
  		goto bail;
  	}
  	memcpy((*alloc_copy), alloc_bh->b_data, alloc_bh->b_size);
  
  	alloc = (struct ocfs2_dinode *) alloc_bh->b_data;
  	ocfs2_clear_local_alloc(alloc);

  	ocfs2_compute_meta_ecc(osb->sb, alloc_bh->b_data, &alloc->i_check);

  	status = ocfs2_write_block(osb, alloc_bh, INODE_CACHE(inode));

  	if (status < 0)
  		mlog_errno(status);
  
  bail:
  	if ((status < 0) && (*alloc_copy)) {
  		kfree(*alloc_copy);
  		*alloc_copy = NULL;
  	}

  	brelse(alloc_bh);

  
  	if (inode) {

  		mutex_unlock(&inode->i_mutex);

  		iput(inode);
  	}

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  /*
   * Step 2: By now, we've completed the journal recovery, we've stamped
   * a clean local alloc on disk and dropped the node out of the
   * recovery map. Dlm locks will no longer stall, so lets clear out the
   * main bitmap.
   */
  int ocfs2_complete_local_alloc_recovery(struct ocfs2_super *osb,
  					struct ocfs2_dinode *alloc)
  {
  	int status;

  	handle_t *handle;

  	struct buffer_head *main_bm_bh = NULL;

  	struct inode *main_bm_inode;

  	main_bm_inode = ocfs2_get_system_file_inode(osb,
  						    GLOBAL_BITMAP_SYSTEM_INODE,
  						    OCFS2_INVALID_SLOT);
  	if (!main_bm_inode) {
  		status = -EINVAL;
  		mlog_errno(status);

  		goto out;

  	}

  	mutex_lock(&main_bm_inode->i_mutex);

  	status = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 1);

  	if (status < 0) {
  		mlog_errno(status);

  		goto out_mutex;

  	}

  	handle = ocfs2_start_trans(osb, OCFS2_WINDOW_MOVE_CREDITS);

  	if (IS_ERR(handle)) {
  		status = PTR_ERR(handle);
  		handle = NULL;
  		mlog_errno(status);

  		goto out_unlock;

  	}
  
  	/* we want the bitmap change to be recorded on disk asap */

  	handle->h_sync = 1;

  
  	status = ocfs2_sync_local_to_main(osb, handle, alloc,
  					  main_bm_inode, main_bm_bh);
  	if (status < 0)
  		mlog_errno(status);

  	ocfs2_commit_trans(osb, handle);

  
  out_unlock:

  	ocfs2_inode_unlock(main_bm_inode, 1);

  
  out_mutex:
  	mutex_unlock(&main_bm_inode->i_mutex);

  	brelse(main_bm_bh);

  	iput(main_bm_inode);

  out:

  	if (!status)

  		ocfs2_init_steal_slots(osb);

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  /*

   * make sure we've got at least bits_wanted contiguous bits in the

   * local alloc. You lose them when you drop i_mutex.

   *
   * We will add ourselves to the transaction passed in, but may start
   * our own in order to shift windows.
   */
  int ocfs2_reserve_local_alloc_bits(struct ocfs2_super *osb,

  				   u32 bits_wanted,
  				   struct ocfs2_alloc_context *ac)
  {
  	int status;
  	struct ocfs2_dinode *alloc;
  	struct inode *local_alloc_inode;
  	unsigned int free_bits;

  	BUG_ON(!ac);

  
  	local_alloc_inode =
  		ocfs2_get_system_file_inode(osb,
  					    LOCAL_ALLOC_SYSTEM_INODE,
  					    osb->slot_num);
  	if (!local_alloc_inode) {
  		status = -ENOENT;
  		mlog_errno(status);
  		goto bail;
  	}

  
  	mutex_lock(&local_alloc_inode->i_mutex);

  	/*
  	 * We must double check state and allocator bits because
  	 * another process may have changed them while holding i_mutex.
  	 */
  	spin_lock(&osb->osb_lock);
  	if (!ocfs2_la_state_enabled(osb) ||
  	    (bits_wanted > osb->local_alloc_bits)) {
  		spin_unlock(&osb->osb_lock);

  		status = -ENOSPC;
  		goto bail;
  	}

  	spin_unlock(&osb->osb_lock);

  
  	alloc = (struct ocfs2_dinode *) osb->local_alloc_bh->b_data;

  #ifdef CONFIG_OCFS2_DEBUG_FS

  	if (le32_to_cpu(alloc->id1.bitmap1.i_used) !=
  	    ocfs2_local_alloc_count_bits(alloc)) {

  		ocfs2_error(osb->sb, "local alloc inode %llu says it has "

  			    "%u free bits, but a count shows %u",

  			    (unsigned long long)le64_to_cpu(alloc->i_blkno),

  			    le32_to_cpu(alloc->id1.bitmap1.i_used),
  			    ocfs2_local_alloc_count_bits(alloc));
  		status = -EIO;
  		goto bail;
  	}

  #endif

  
  	free_bits = le32_to_cpu(alloc->id1.bitmap1.i_total) -
  		le32_to_cpu(alloc->id1.bitmap1.i_used);
  	if (bits_wanted > free_bits) {
  		/* uhoh, window change time. */
  		status =
  			ocfs2_local_alloc_slide_window(osb, local_alloc_inode);
  		if (status < 0) {
  			if (status != -ENOSPC)
  				mlog_errno(status);
  			goto bail;
  		}

  
  		/*
  		 * Under certain conditions, the window slide code
  		 * might have reduced the number of bits available or
  		 * disabled the the local alloc entirely. Re-check
  		 * here and return -ENOSPC if necessary.
  		 */
  		status = -ENOSPC;
  		if (!ocfs2_la_state_enabled(osb))
  			goto bail;
  
  		free_bits = le32_to_cpu(alloc->id1.bitmap1.i_total) -
  			le32_to_cpu(alloc->id1.bitmap1.i_used);
  		if (bits_wanted > free_bits)
  			goto bail;

  	}

  	ac->ac_inode = local_alloc_inode;

  	/* We should never use localalloc from another slot */
  	ac->ac_alloc_slot = osb->slot_num;

  	ac->ac_which = OCFS2_AC_USE_LOCAL;

  	get_bh(osb->local_alloc_bh);
  	ac->ac_bh = osb->local_alloc_bh;

  	status = 0;
  bail:

  	if (status < 0 && local_alloc_inode) {
  		mutex_unlock(&local_alloc_inode->i_mutex);

  		iput(local_alloc_inode);

  	}

  	trace_ocfs2_reserve_local_alloc_bits(
  		(unsigned long long)ac->ac_max_block,
  		bits_wanted, osb->slot_num, status);

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  int ocfs2_claim_local_alloc_bits(struct ocfs2_super *osb,

  				 handle_t *handle,

  				 struct ocfs2_alloc_context *ac,

  				 u32 bits_wanted,

  				 u32 *bit_off,
  				 u32 *num_bits)
  {
  	int status, start;
  	struct inode *local_alloc_inode;

  	void *bitmap;
  	struct ocfs2_dinode *alloc;
  	struct ocfs2_local_alloc *la;

  	BUG_ON(ac->ac_which != OCFS2_AC_USE_LOCAL);

  	local_alloc_inode = ac->ac_inode;
  	alloc = (struct ocfs2_dinode *) osb->local_alloc_bh->b_data;
  	la = OCFS2_LOCAL_ALLOC(alloc);

  	start = ocfs2_local_alloc_find_clear_bits(osb, alloc, &bits_wanted,
  						  ac->ac_resv);

  	if (start == -1) {
  		/* TODO: Shouldn't we just BUG here? */
  		status = -ENOSPC;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	bitmap = la->la_bitmap;
  	*bit_off = le32_to_cpu(la->la_bm_off) + start;

  	*num_bits = bits_wanted;

  	status = ocfs2_journal_access_di(handle,
  					 INODE_CACHE(local_alloc_inode),

  					 osb->local_alloc_bh,
  					 OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}

  	ocfs2_resmap_claimed_bits(&osb->osb_la_resmap, ac->ac_resv, start,
  				  bits_wanted);

  	while(bits_wanted--)
  		ocfs2_set_bit(start++, bitmap);

  	le32_add_cpu(&alloc->id1.bitmap1.i_used, *num_bits);

  	ocfs2_journal_dirty(handle, osb->local_alloc_bh);

  bail:

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  static u32 ocfs2_local_alloc_count_bits(struct ocfs2_dinode *alloc)
  {
  	int i;
  	u8 *buffer;
  	u32 count = 0;
  	struct ocfs2_local_alloc *la = OCFS2_LOCAL_ALLOC(alloc);

  	buffer = la->la_bitmap;
  	for (i = 0; i < le16_to_cpu(la->la_size); i++)
  		count += hweight8(buffer[i]);

  	trace_ocfs2_local_alloc_count_bits(count);

  	return count;
  }
  
  static int ocfs2_local_alloc_find_clear_bits(struct ocfs2_super *osb,

  				     struct ocfs2_dinode *alloc,
  				     u32 *numbits,
  				     struct ocfs2_alloc_reservation *resv)

  {
  	int numfound, bitoff, left, startoff, lastzero;

  	int local_resv = 0;
  	struct ocfs2_alloc_reservation r;

  	void *bitmap = NULL;

  	struct ocfs2_reservation_map *resmap = &osb->osb_la_resmap;

  	if (!alloc->id1.bitmap1.i_total) {

  		bitoff = -1;
  		goto bail;
  	}

  	if (!resv) {
  		local_resv = 1;
  		ocfs2_resv_init_once(&r);
  		ocfs2_resv_set_type(&r, OCFS2_RESV_FLAG_TMP);
  		resv = &r;
  	}
  
  	numfound = *numbits;
  	if (ocfs2_resmap_resv_bits(resmap, resv, &bitoff, &numfound) == 0) {
  		if (numfound < *numbits)
  			*numbits = numfound;
  		goto bail;
  	}
  
  	/*
  	 * Code error. While reservations are enabled, local
  	 * allocation should _always_ go through them.
  	 */
  	BUG_ON(osb->osb_resv_level != 0);
  
  	/*
  	 * Reservations are disabled. Handle this the old way.
  	 */

  	bitmap = OCFS2_LOCAL_ALLOC(alloc)->la_bitmap;
  
  	numfound = bitoff = startoff = 0;
  	lastzero = -1;
  	left = le32_to_cpu(alloc->id1.bitmap1.i_total);
  	while ((bitoff = ocfs2_find_next_zero_bit(bitmap, left, startoff)) != -1) {
  		if (bitoff == left) {
  			/* mlog(0, "bitoff (%d) == left", bitoff); */
  			break;
  		}
  		/* mlog(0, "Found a zero: bitoff = %d, startoff = %d, "
  		   "numfound = %d
  ", bitoff, startoff, numfound);*/
  
  		/* Ok, we found a zero bit... is it contig. or do we
  		 * start over?*/
  		if (bitoff == startoff) {
  			/* we found a zero */
  			numfound++;
  			startoff++;
  		} else {
  			/* got a zero after some ones */
  			numfound = 1;
  			startoff = bitoff+1;
  		}
  		/* we got everything we needed */

  		if (numfound == *numbits) {

  			/* mlog(0, "Found it all!
  "); */
  			break;
  		}
  	}

  	trace_ocfs2_local_alloc_find_clear_bits_search_bitmap(bitoff, numfound);

  	if (numfound == *numbits)

  		bitoff = startoff - numfound;

  	else

  		bitoff = -1;
  
  bail:

  	if (local_resv)
  		ocfs2_resv_discard(resmap, resv);

  	trace_ocfs2_local_alloc_find_clear_bits(*numbits,
  		le32_to_cpu(alloc->id1.bitmap1.i_total),
  		bitoff, numfound);

  	return bitoff;
  }
  
  static void ocfs2_clear_local_alloc(struct ocfs2_dinode *alloc)
  {
  	struct ocfs2_local_alloc *la = OCFS2_LOCAL_ALLOC(alloc);
  	int i;

  
  	alloc->id1.bitmap1.i_total = 0;
  	alloc->id1.bitmap1.i_used = 0;
  	la->la_bm_off = 0;
  	for(i = 0; i < le16_to_cpu(la->la_size); i++)
  		la->la_bitmap[i] = 0;

  }
  
  #if 0
  /* turn this on and uncomment below to aid debugging window shifts. */
  static void ocfs2_verify_zero_bits(unsigned long *bitmap,
  				   unsigned int start,
  				   unsigned int count)
  {
  	unsigned int tmp = count;
  	while(tmp--) {
  		if (ocfs2_test_bit(start + tmp, bitmap)) {
  			printk("ocfs2_verify_zero_bits: start = %u, count = "
  			       "%u
  ", start, count);
  			printk("ocfs2_verify_zero_bits: bit %u is set!",
  			       start + tmp);
  			BUG();
  		}
  	}
  }
  #endif
  
  /*
   * sync the local alloc to main bitmap.
   *
   * assumes you've already locked the main bitmap -- the bitmap inode
   * passed is used for caching.
   */
  static int ocfs2_sync_local_to_main(struct ocfs2_super *osb,

  				    handle_t *handle,

  				    struct ocfs2_dinode *alloc,
  				    struct inode *main_bm_inode,
  				    struct buffer_head *main_bm_bh)
  {
  	int status = 0;
  	int bit_off, left, count, start;
  	u64 la_start_blk;
  	u64 blkno;
  	void *bitmap;
  	struct ocfs2_local_alloc *la = OCFS2_LOCAL_ALLOC(alloc);

  	trace_ocfs2_sync_local_to_main(

  	     le32_to_cpu(alloc->id1.bitmap1.i_total),
  	     le32_to_cpu(alloc->id1.bitmap1.i_used));

  
  	if (!alloc->id1.bitmap1.i_total) {

  		goto bail;
  	}
  
  	if (le32_to_cpu(alloc->id1.bitmap1.i_used) ==
  	    le32_to_cpu(alloc->id1.bitmap1.i_total)) {

  		goto bail;
  	}
  
  	la_start_blk = ocfs2_clusters_to_blocks(osb->sb,
  						le32_to_cpu(la->la_bm_off));
  	bitmap = la->la_bitmap;
  	start = count = bit_off = 0;
  	left = le32_to_cpu(alloc->id1.bitmap1.i_total);
  
  	while ((bit_off = ocfs2_find_next_zero_bit(bitmap, left, start))
  	       != -1) {
  		if ((bit_off < left) && (bit_off == start)) {
  			count++;
  			start++;
  			continue;
  		}
  		if (count) {
  			blkno = la_start_blk +
  				ocfs2_clusters_to_blocks(osb->sb,
  							 start - count);

  			trace_ocfs2_sync_local_to_main_free(

  			     count, start - count,
  			     (unsigned long long)la_start_blk,
  			     (unsigned long long)blkno);

  			status = ocfs2_release_clusters(handle,
  							main_bm_inode,
  							main_bm_bh, blkno,
  							count);

  			if (status < 0) {
  				mlog_errno(status);
  				goto bail;
  			}
  		}
  		if (bit_off >= left)
  			break;
  		count = 1;
  		start = bit_off + 1;
  	}
  
  bail:

  	if (status)
  		mlog_errno(status);

  	return status;
  }

  enum ocfs2_la_event {
  	OCFS2_LA_EVENT_SLIDE,		/* Normal window slide. */
  	OCFS2_LA_EVENT_FRAGMENTED,	/* The global bitmap has
  					 * enough bits theoretically
  					 * free, but a contiguous
  					 * allocation could not be
  					 * found. */
  	OCFS2_LA_EVENT_ENOSPC,		/* Global bitmap doesn't have
  					 * enough bits free to satisfy
  					 * our request. */
  };
  #define OCFS2_LA_ENABLE_INTERVAL (30 * HZ)
  /*
   * Given an event, calculate the size of our next local alloc window.
   *
   * This should always be called under i_mutex of the local alloc inode
   * so that local alloc disabling doesn't race with processes trying to
   * use the allocator.
   *
   * Returns the state which the local alloc was left in. This value can
   * be ignored by some paths.
   */
  static int ocfs2_recalc_la_window(struct ocfs2_super *osb,
  				  enum ocfs2_la_event event)
  {
  	unsigned int bits;
  	int state;
  
  	spin_lock(&osb->osb_lock);
  	if (osb->local_alloc_state == OCFS2_LA_DISABLED) {
  		WARN_ON_ONCE(osb->local_alloc_state == OCFS2_LA_DISABLED);
  		goto out_unlock;
  	}
  
  	/*
  	 * ENOSPC and fragmentation are treated similarly for now.
  	 */
  	if (event == OCFS2_LA_EVENT_ENOSPC ||
  	    event == OCFS2_LA_EVENT_FRAGMENTED) {
  		/*
  		 * We ran out of contiguous space in the primary
  		 * bitmap. Drastically reduce the number of bits used
  		 * by local alloc until we have to disable it.
  		 */
  		bits = osb->local_alloc_bits >> 1;
  		if (bits > ocfs2_megabytes_to_clusters(osb->sb, 1)) {
  			/*
  			 * By setting state to THROTTLED, we'll keep
  			 * the number of local alloc bits used down
  			 * until an event occurs which would give us
  			 * reason to assume the bitmap situation might
  			 * have changed.
  			 */
  			osb->local_alloc_state = OCFS2_LA_THROTTLED;
  			osb->local_alloc_bits = bits;
  		} else {
  			osb->local_alloc_state = OCFS2_LA_DISABLED;
  		}
  		queue_delayed_work(ocfs2_wq, &osb->la_enable_wq,
  				   OCFS2_LA_ENABLE_INTERVAL);
  		goto out_unlock;
  	}
  
  	/*
  	 * Don't increase the size of the local alloc window until we
  	 * know we might be able to fulfill the request. Otherwise, we
  	 * risk bouncing around the global bitmap during periods of
  	 * low space.
  	 */
  	if (osb->local_alloc_state != OCFS2_LA_THROTTLED)
  		osb->local_alloc_bits = osb->local_alloc_default_bits;
  
  out_unlock:
  	state = osb->local_alloc_state;
  	spin_unlock(&osb->osb_lock);
  
  	return state;
  }

  static int ocfs2_local_alloc_reserve_for_window(struct ocfs2_super *osb,

  						struct ocfs2_alloc_context **ac,
  						struct inode **bitmap_inode,
  						struct buffer_head **bitmap_bh)
  {
  	int status;

  	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);

  	if (!(*ac)) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}

  retry_enospc:

  	(*ac)->ac_bits_wanted = osb->local_alloc_default_bits;

  	status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);

  	if (status == -ENOSPC) {
  		if (ocfs2_recalc_la_window(osb, OCFS2_LA_EVENT_ENOSPC) ==
  		    OCFS2_LA_DISABLED)
  			goto bail;
  
  		ocfs2_free_ac_resource(*ac);
  		memset(*ac, 0, sizeof(struct ocfs2_alloc_context));
  		goto retry_enospc;
  	}

  	if (status < 0) {

  		mlog_errno(status);

  		goto bail;
  	}
  
  	*bitmap_inode = (*ac)->ac_inode;
  	igrab(*bitmap_inode);
  	*bitmap_bh = (*ac)->ac_bh;
  	get_bh(*bitmap_bh);
  	status = 0;
  bail:
  	if ((status < 0) && *ac) {
  		ocfs2_free_alloc_context(*ac);
  		*ac = NULL;
  	}

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  /*
   * pass it the bitmap lock in lock_bh if you have it.
   */
  static int ocfs2_local_alloc_new_window(struct ocfs2_super *osb,

  					handle_t *handle,

  					struct ocfs2_alloc_context *ac)
  {
  	int status = 0;
  	u32 cluster_off, cluster_count;
  	struct ocfs2_dinode *alloc = NULL;
  	struct ocfs2_local_alloc *la;

  	alloc = (struct ocfs2_dinode *) osb->local_alloc_bh->b_data;
  	la = OCFS2_LOCAL_ALLOC(alloc);

  	trace_ocfs2_local_alloc_new_window(
  		le32_to_cpu(alloc->id1.bitmap1.i_total),
  		osb->local_alloc_bits);

  
  	/* Instruct the allocation code to try the most recently used
  	 * cluster group. We'll re-record the group used this pass
  	 * below. */
  	ac->ac_last_group = osb->la_last_gd;

  	/* we used the generic suballoc reserve function, but we set
  	 * everything up nicely, so there's no reason why we can't use
  	 * the more specific cluster api to claim bits. */

  	status = ocfs2_claim_clusters(handle, ac, osb->local_alloc_bits,

  				      &cluster_off, &cluster_count);

  	if (status == -ENOSPC) {
  retry_enospc:
  		/*
  		 * Note: We could also try syncing the journal here to
  		 * allow use of any free bits which the current
  		 * transaction can't give us access to. --Mark
  		 */
  		if (ocfs2_recalc_la_window(osb, OCFS2_LA_EVENT_FRAGMENTED) ==
  		    OCFS2_LA_DISABLED)
  			goto bail;

  		ac->ac_bits_wanted = osb->local_alloc_default_bits;

  		status = ocfs2_claim_clusters(handle, ac,

  					      osb->local_alloc_bits,
  					      &cluster_off,
  					      &cluster_count);
  		if (status == -ENOSPC)
  			goto retry_enospc;
  		/*
  		 * We only shrunk the *minimum* number of in our
  		 * request - it's entirely possible that the allocator
  		 * might give us more than we asked for.
  		 */
  		if (status == 0) {
  			spin_lock(&osb->osb_lock);
  			osb->local_alloc_bits = cluster_count;
  			spin_unlock(&osb->osb_lock);
  		}
  	}

  	if (status < 0) {
  		if (status != -ENOSPC)
  			mlog_errno(status);
  		goto bail;
  	}

  	osb->la_last_gd = ac->ac_last_group;

  	la->la_bm_off = cpu_to_le32(cluster_off);
  	alloc->id1.bitmap1.i_total = cpu_to_le32(cluster_count);
  	/* just in case... In the future when we find space ourselves,
  	 * we don't have to get all contiguous -- but we'll have to
  	 * set all previously used bits in bitmap and update
  	 * la_bits_set before setting the bits in the main bitmap. */
  	alloc->id1.bitmap1.i_used = 0;
  	memset(OCFS2_LOCAL_ALLOC(alloc)->la_bitmap, 0,
  	       le16_to_cpu(la->la_size));

  	ocfs2_resmap_restart(&osb->osb_la_resmap, cluster_count,
  			     OCFS2_LOCAL_ALLOC(alloc)->la_bitmap);

  	trace_ocfs2_local_alloc_new_window_result(
  		OCFS2_LOCAL_ALLOC(alloc)->la_bm_off,
  		le32_to_cpu(alloc->id1.bitmap1.i_total));

  
  bail:

  	if (status)
  		mlog_errno(status);

  	return status;
  }
  
  /* Note that we do *NOT* lock the local alloc inode here as
   * it's been locked already for us. */
  static int ocfs2_local_alloc_slide_window(struct ocfs2_super *osb,
  					  struct inode *local_alloc_inode)
  {
  	int status = 0;
  	struct buffer_head *main_bm_bh = NULL;
  	struct inode *main_bm_inode = NULL;

  	handle_t *handle = NULL;

  	struct ocfs2_dinode *alloc;
  	struct ocfs2_dinode *alloc_copy = NULL;
  	struct ocfs2_alloc_context *ac = NULL;

  	ocfs2_recalc_la_window(osb, OCFS2_LA_EVENT_SLIDE);

  	/* This will lock the main bitmap for us. */
  	status = ocfs2_local_alloc_reserve_for_window(osb,

  						      &ac,
  						      &main_bm_inode,
  						      &main_bm_bh);
  	if (status < 0) {
  		if (status != -ENOSPC)
  			mlog_errno(status);
  		goto bail;
  	}

  	handle = ocfs2_start_trans(osb, OCFS2_WINDOW_MOVE_CREDITS);

  	if (IS_ERR(handle)) {
  		status = PTR_ERR(handle);
  		handle = NULL;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	alloc = (struct ocfs2_dinode *) osb->local_alloc_bh->b_data;
  
  	/* We want to clear the local alloc before doing anything
  	 * else, so that if we error later during this operation,
  	 * local alloc shutdown won't try to double free main bitmap
  	 * bits. Make a copy so the sync function knows which bits to
  	 * free. */

  	alloc_copy = kmalloc(osb->local_alloc_bh->b_size, GFP_NOFS);

  	if (!alloc_copy) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}
  	memcpy(alloc_copy, alloc, osb->local_alloc_bh->b_size);

  	status = ocfs2_journal_access_di(handle,
  					 INODE_CACHE(local_alloc_inode),

  					 osb->local_alloc_bh,
  					 OCFS2_JOURNAL_ACCESS_WRITE);

  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	ocfs2_clear_local_alloc(alloc);

  	ocfs2_journal_dirty(handle, osb->local_alloc_bh);

  
  	status = ocfs2_sync_local_to_main(osb, handle, alloc_copy,
  					  main_bm_inode, main_bm_bh);
  	if (status < 0) {
  		mlog_errno(status);
  		goto bail;
  	}
  
  	status = ocfs2_local_alloc_new_window(osb, handle, ac);
  	if (status < 0) {
  		if (status != -ENOSPC)
  			mlog_errno(status);
  		goto bail;
  	}
  
  	atomic_inc(&osb->alloc_stats.moves);

  bail:
  	if (handle)

  		ocfs2_commit_trans(osb, handle);

  	brelse(main_bm_bh);

  
  	if (main_bm_inode)
  		iput(main_bm_inode);
  
  	if (alloc_copy)
  		kfree(alloc_copy);
  
  	if (ac)
  		ocfs2_free_alloc_context(ac);

  	if (status)
  		mlog_errno(status);

  	return status;
  }