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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * refcounttree.c
  *
  * Copyright (C) 2009 Oracle.  All rights reserved.
  */
 
 #include <linux/sort.h>
 #include <cluster/masklog.h>
 #include "ocfs2.h"
 #include "inode.h"
 #include "alloc.h"
 #include "suballoc.h"
 #include "journal.h"
 #include "uptodate.h"
 #include "super.h"
 #include "buffer_head_io.h"
 #include "blockcheck.h"
 #include "refcounttree.h"
 #include "sysfile.h"
 #include "dlmglue.h"
 #include "extent_map.h"
 #include "aops.h"
 #include "xattr.h"
 #include "namei.h"
 #include "ocfs2_trace.h"
 #include "file.h"
 
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
 #include <linux/writeback.h>
 #include <linux/pagevec.h>
 #include <linux/swap.h>
 #include <linux/security.h>
 #include <linux/fsnotify.h>
 #include <linux/quotaops.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/posix_acl.h>
 
 struct ocfs2_cow_context {
     struct inode *inode;
     u32 cow_start;
     u32 cow_len;
     struct ocfs2_extent_tree data_et;
     struct ocfs2_refcount_tree *ref_tree;
     struct buffer_head *ref_root_bh;
     struct ocfs2_alloc_context *meta_ac;
     struct ocfs2_alloc_context *data_ac;
     struct ocfs2_cached_dealloc_ctxt dealloc;
     void *cow_object;
     struct ocfs2_post_refcount *post_refcount;
     int extra_credits;
     int (*get_clusters)(struct ocfs2_cow_context *context,
                 u32 v_cluster, u32 *p_cluster,
                 u32 *num_clusters,
                 unsigned int *extent_flags);
     int (*cow_duplicate_clusters)(handle_t *handle,
                       struct inode *inode,
                       u32 cpos, u32 old_cluster,
                       u32 new_cluster, u32 new_len);
 };
 
 static inline struct ocfs2_refcount_tree *
 cache_info_to_refcount(struct ocfs2_caching_info *ci)
 {
     return container_of(ci, struct ocfs2_refcount_tree, rf_ci);
 }
 
 static int ocfs2_validate_refcount_block(struct super_block *sb,
                      struct buffer_head *bh)
 {
     int rc;
     struct ocfs2_refcount_block *rb =
         (struct ocfs2_refcount_block *)bh->b_data;
 
     trace_ocfs2_validate_refcount_block((unsigned long long)bh->b_blocknr);
 
     BUG_ON(!buffer_uptodate(bh));
 
     /*
      * If the ecc fails, we return the error but otherwise
      * leave the filesystem running.  We know any error is
      * local to this block.
      */
     rc = ocfs2_validate_meta_ecc(sb, bh->b_data, &rb->rf_check);
     if (rc) {
         mlog(ML_ERROR, "Checksum failed for refcount block %llu\n",
              (unsigned long long)bh->b_blocknr);
         return rc;
     }
 
 
     if (!OCFS2_IS_VALID_REFCOUNT_BLOCK(rb)) {
         rc = ocfs2_error(sb,
                  "Refcount block #%llu has bad signature %.*s\n",
                  (unsigned long long)bh->b_blocknr, 7,
                  rb->rf_signature);
         goto out;
     }
 
     if (le64_to_cpu(rb->rf_blkno) != bh->b_blocknr) {
         rc = ocfs2_error(sb,
                  "Refcount block #%llu has an invalid rf_blkno of %llu\n",
                  (unsigned long long)bh->b_blocknr,
                  (unsigned long long)le64_to_cpu(rb->rf_blkno));
         goto out;
     }
 
     if (le32_to_cpu(rb->rf_fs_generation) != OCFS2_SB(sb)->fs_generation) {
         rc = ocfs2_error(sb,
                  "Refcount block #%llu has an invalid rf_fs_generation of #%u\n",
                  (unsigned long long)bh->b_blocknr,
                  le32_to_cpu(rb->rf_fs_generation));
         goto out;
     }
 out:
     return rc;
 }
 
 static int ocfs2_read_refcount_block(struct ocfs2_caching_info *ci,
                      u64 rb_blkno,
                      struct buffer_head **bh)
 {
     int rc;
     struct buffer_head *tmp = *bh;
 
     rc = ocfs2_read_block(ci, rb_blkno, &tmp,
                   ocfs2_validate_refcount_block);
 
     /* If ocfs2_read_block() got us a new bh, pass it up. */
     if (!rc && !*bh)
         *bh = tmp;
 
     return rc;
 }
 
 static u64 ocfs2_refcount_cache_owner(struct ocfs2_caching_info *ci)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     return rf->rf_blkno;
 }
 
 static struct super_block *
 ocfs2_refcount_cache_get_super(struct ocfs2_caching_info *ci)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     return rf->rf_sb;
 }
 
 static void ocfs2_refcount_cache_lock(struct ocfs2_caching_info *ci)
 __acquires(&rf->rf_lock)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     spin_lock(&rf->rf_lock);
 }
 
 static void ocfs2_refcount_cache_unlock(struct ocfs2_caching_info *ci)
 __releases(&rf->rf_lock)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     spin_unlock(&rf->rf_lock);
 }
 
 static void ocfs2_refcount_cache_io_lock(struct ocfs2_caching_info *ci)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     mutex_lock(&rf->rf_io_mutex);
 }
 
 static void ocfs2_refcount_cache_io_unlock(struct ocfs2_caching_info *ci)
 {
     struct ocfs2_refcount_tree *rf = cache_info_to_refcount(ci);
 
     mutex_unlock(&rf->rf_io_mutex);
 }
 
 static const struct ocfs2_caching_operations ocfs2_refcount_caching_ops = {
     .co_owner       = ocfs2_refcount_cache_owner,
     .co_get_super       = ocfs2_refcount_cache_get_super,
     .co_cache_lock      = ocfs2_refcount_cache_lock,
     .co_cache_unlock    = ocfs2_refcount_cache_unlock,
     .co_io_lock     = ocfs2_refcount_cache_io_lock,
     .co_io_unlock       = ocfs2_refcount_cache_io_unlock,
 };
 
 static struct ocfs2_refcount_tree *
 ocfs2_find_refcount_tree(struct ocfs2_super *osb, u64 blkno)
 {
     struct rb_node *n = osb->osb_rf_lock_tree.rb_node;
     struct ocfs2_refcount_tree *tree = NULL;
 
     while (n) {
         tree = rb_entry(n, struct ocfs2_refcount_tree, rf_node);
 
         if (blkno < tree->rf_blkno)
             n = n->rb_left;
         else if (blkno > tree->rf_blkno)
             n = n->rb_right;
         else
             return tree;
     }
 
     return NULL;
 }
 
 /* osb_lock is already locked. */
 static void ocfs2_insert_refcount_tree(struct ocfs2_super *osb,
                        struct ocfs2_refcount_tree *new)
 {
     u64 rf_blkno = new->rf_blkno;
     struct rb_node *parent = NULL;
     struct rb_node **p = &osb->osb_rf_lock_tree.rb_node;
     struct ocfs2_refcount_tree *tmp;
 
     while (*p) {
         parent = *p;
 
         tmp = rb_entry(parent, struct ocfs2_refcount_tree,
                    rf_node);
 
         if (rf_blkno < tmp->rf_blkno)
             p = &(*p)->rb_left;
         else if (rf_blkno > tmp->rf_blkno)
             p = &(*p)->rb_right;
         else {
             /* This should never happen! */
             mlog(ML_ERROR, "Duplicate refcount block %llu found!\n",
                  (unsigned long long)rf_blkno);
             BUG();
         }
     }
 
     rb_link_node(&new->rf_node, parent, p);
     rb_insert_color(&new->rf_node, &osb->osb_rf_lock_tree);
 }
 
 static void ocfs2_free_refcount_tree(struct ocfs2_refcount_tree *tree)
 {
     ocfs2_metadata_cache_exit(&tree->rf_ci);
     ocfs2_simple_drop_lockres(OCFS2_SB(tree->rf_sb), &tree->rf_lockres);
     ocfs2_lock_res_free(&tree->rf_lockres);
     kfree(tree);
 }
 
 static inline void
 ocfs2_erase_refcount_tree_from_list_no_lock(struct ocfs2_super *osb,
                     struct ocfs2_refcount_tree *tree)
 {
     rb_erase(&tree->rf_node, &osb->osb_rf_lock_tree);
     if (osb->osb_ref_tree_lru && osb->osb_ref_tree_lru == tree)
         osb->osb_ref_tree_lru = NULL;
 }
 
 static void ocfs2_erase_refcount_tree_from_list(struct ocfs2_super *osb,
                     struct ocfs2_refcount_tree *tree)
 {
     spin_lock(&osb->osb_lock);
     ocfs2_erase_refcount_tree_from_list_no_lock(osb, tree);
     spin_unlock(&osb->osb_lock);
 }
 
 static void ocfs2_kref_remove_refcount_tree(struct kref *kref)
 {
     struct ocfs2_refcount_tree *tree =
         container_of(kref, struct ocfs2_refcount_tree, rf_getcnt);
 
     ocfs2_free_refcount_tree(tree);
 }
 
 static inline void
 ocfs2_refcount_tree_get(struct ocfs2_refcount_tree *tree)
 {
     kref_get(&tree->rf_getcnt);
 }
 
 static inline void
 ocfs2_refcount_tree_put(struct ocfs2_refcount_tree *tree)
 {
     kref_put(&tree->rf_getcnt, ocfs2_kref_remove_refcount_tree);
 }
 
 static inline void ocfs2_init_refcount_tree_ci(struct ocfs2_refcount_tree *new,
                            struct super_block *sb)
 {
     ocfs2_metadata_cache_init(&new->rf_ci, &ocfs2_refcount_caching_ops);
     mutex_init(&new->rf_io_mutex);
     new->rf_sb = sb;
     spin_lock_init(&new->rf_lock);
 }
 
 static inline void ocfs2_init_refcount_tree_lock(struct ocfs2_super *osb,
                     struct ocfs2_refcount_tree *new,
                     u64 rf_blkno, u32 generation)
 {
     init_rwsem(&new->rf_sem);
     ocfs2_refcount_lock_res_init(&new->rf_lockres, osb,
                      rf_blkno, generation);
 }
 
 static struct ocfs2_refcount_tree*
 ocfs2_allocate_refcount_tree(struct ocfs2_super *osb, u64 rf_blkno)
 {
     struct ocfs2_refcount_tree *new;
 
     new = kzalloc(sizeof(struct ocfs2_refcount_tree), GFP_NOFS);
     if (!new)
         return NULL;
 
     new->rf_blkno = rf_blkno;
     kref_init(&new->rf_getcnt);
     ocfs2_init_refcount_tree_ci(new, osb->sb);
 
     return new;
 }
 
 static int ocfs2_get_refcount_tree(struct ocfs2_super *osb, u64 rf_blkno,
                    struct ocfs2_refcount_tree **ret_tree)
 {
     int ret = 0;
     struct ocfs2_refcount_tree *tree, *new = NULL;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_block *ref_rb;
 
     spin_lock(&osb->osb_lock);
     if (osb->osb_ref_tree_lru &&
         osb->osb_ref_tree_lru->rf_blkno == rf_blkno)
         tree = osb->osb_ref_tree_lru;
     else
         tree = ocfs2_find_refcount_tree(osb, rf_blkno);
     if (tree)
         goto out;
 
     spin_unlock(&osb->osb_lock);
 
     new = ocfs2_allocate_refcount_tree(osb, rf_blkno);
     if (!new) {
         ret = -ENOMEM;
         mlog_errno(ret);
         return ret;
     }
     /*
      * We need the generation to create the refcount tree lock and since
      * it isn't changed during the tree modification, we are safe here to
      * read without protection.
      * We also have to purge the cache after we create the lock since the
      * refcount block may have the stale data. It can only be trusted when
      * we hold the refcount lock.
      */
     ret = ocfs2_read_refcount_block(&new->rf_ci, rf_blkno, &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         ocfs2_metadata_cache_exit(&new->rf_ci);
         kfree(new);
         return ret;
     }
 
     ref_rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     new->rf_generation = le32_to_cpu(ref_rb->rf_generation);
     ocfs2_init_refcount_tree_lock(osb, new, rf_blkno,
                       new->rf_generation);
     ocfs2_metadata_cache_purge(&new->rf_ci);
 
     spin_lock(&osb->osb_lock);
     tree = ocfs2_find_refcount_tree(osb, rf_blkno);
     if (tree)
         goto out;
 
     ocfs2_insert_refcount_tree(osb, new);
 
     tree = new;
     new = NULL;
 
 out:
     *ret_tree = tree;
 
     osb->osb_ref_tree_lru = tree;
 
     spin_unlock(&osb->osb_lock);
 
     if (new)
         ocfs2_free_refcount_tree(new);
 
     brelse(ref_root_bh);
     return ret;
 }
 
 static int ocfs2_get_refcount_block(struct inode *inode, u64 *ref_blkno)
 {
     int ret;
     struct buffer_head *di_bh = NULL;
     struct ocfs2_dinode *di;
 
     ret = ocfs2_read_inode_block(inode, &di_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     BUG_ON(!ocfs2_is_refcount_inode(inode));
 
     di = (struct ocfs2_dinode *)di_bh->b_data;
     *ref_blkno = le64_to_cpu(di->i_refcount_loc);
     brelse(di_bh);
 out:
     return ret;
 }
 
 static int __ocfs2_lock_refcount_tree(struct ocfs2_super *osb,
                       struct ocfs2_refcount_tree *tree, int rw)
 {
     int ret;
 
     ret = ocfs2_refcount_lock(tree, rw);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     if (rw)
         down_write(&tree->rf_sem);
     else
         down_read(&tree->rf_sem);
 
 out:
     return ret;
 }
 
 /*
  * Lock the refcount tree pointed by ref_blkno and return the tree.
  * In most case, we lock the tree and read the refcount block.
  * So read it here if the caller really needs it.
  *
  * If the tree has been re-created by other node, it will free the
  * old one and re-create it.
  */
 int ocfs2_lock_refcount_tree(struct ocfs2_super *osb,
                  u64 ref_blkno, int rw,
                  struct ocfs2_refcount_tree **ret_tree,
                  struct buffer_head **ref_bh)
 {
     int ret, delete_tree = 0;
     struct ocfs2_refcount_tree *tree = NULL;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_block *rb;
 
 again:
     ret = ocfs2_get_refcount_tree(osb, ref_blkno, &tree);
     if (ret) {
         mlog_errno(ret);
         return ret;
     }
 
     ocfs2_refcount_tree_get(tree);
 
     ret = __ocfs2_lock_refcount_tree(osb, tree, rw);
     if (ret) {
         mlog_errno(ret);
         ocfs2_refcount_tree_put(tree);
         goto out;
     }
 
     ret = ocfs2_read_refcount_block(&tree->rf_ci, tree->rf_blkno,
                     &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         ocfs2_unlock_refcount_tree(osb, tree, rw);
         goto out;
     }
 
     rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     /*
      * If the refcount block has been freed and re-created, we may need
      * to recreate the refcount tree also.
      *
      * Here we just remove the tree from the rb-tree, and the last
      * kref holder will unlock and delete this refcount_tree.
      * Then we goto "again" and ocfs2_get_refcount_tree will create
      * the new refcount tree for us.
      */
     if (tree->rf_generation != le32_to_cpu(rb->rf_generation)) {
         if (!tree->rf_removed) {
             ocfs2_erase_refcount_tree_from_list(osb, tree);
             tree->rf_removed = 1;
             delete_tree = 1;
         }
 
         ocfs2_unlock_refcount_tree(osb, tree, rw);
         /*
          * We get an extra reference when we create the refcount
          * tree, so another put will destroy it.
          */
         if (delete_tree)
             ocfs2_refcount_tree_put(tree);
         brelse(ref_root_bh);
         ref_root_bh = NULL;
         goto again;
     }
 
     *ret_tree = tree;
     if (ref_bh) {
         *ref_bh = ref_root_bh;
         ref_root_bh = NULL;
     }
 out:
     brelse(ref_root_bh);
     return ret;
 }
 
 void ocfs2_unlock_refcount_tree(struct ocfs2_super *osb,
                 struct ocfs2_refcount_tree *tree, int rw)
 {
     if (rw)
         up_write(&tree->rf_sem);
     else
         up_read(&tree->rf_sem);
 
     ocfs2_refcount_unlock(tree, rw);
     ocfs2_refcount_tree_put(tree);
 }
 
 void ocfs2_purge_refcount_trees(struct ocfs2_super *osb)
 {
     struct rb_node *node;
     struct ocfs2_refcount_tree *tree;
     struct rb_root *root = &osb->osb_rf_lock_tree;
 
     while ((node = rb_last(root)) != NULL) {
         tree = rb_entry(node, struct ocfs2_refcount_tree, rf_node);
 
         trace_ocfs2_purge_refcount_trees(
                 (unsigned long long) tree->rf_blkno);
 
         rb_erase(&tree->rf_node, root);
         ocfs2_free_refcount_tree(tree);
     }
 }
 
 /*
  * Create a refcount tree for an inode.
  * We take for granted that the inode is already locked.
  */
 static int ocfs2_create_refcount_tree(struct inode *inode,
                       struct buffer_head *di_bh)
 {
     int ret;
     handle_t *handle = NULL;
     struct ocfs2_alloc_context *meta_ac = NULL;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
     struct ocfs2_inode_info *oi = OCFS2_I(inode);
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct buffer_head *new_bh = NULL;
     struct ocfs2_refcount_block *rb;
     struct ocfs2_refcount_tree *new_tree = NULL, *tree = NULL;
     u16 suballoc_bit_start;
     u32 num_got;
     u64 suballoc_loc, first_blkno;
 
     BUG_ON(ocfs2_is_refcount_inode(inode));
 
     trace_ocfs2_create_refcount_tree(
         (unsigned long long)oi->ip_blkno);
 
     ret = ocfs2_reserve_new_metadata_blocks(osb, 1, &meta_ac);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     handle = ocfs2_start_trans(osb, OCFS2_REFCOUNT_TREE_CREATE_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = ocfs2_claim_metadata(handle, meta_ac, 1, &suballoc_loc,
                    &suballoc_bit_start, &num_got,
                    &first_blkno);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     new_tree = ocfs2_allocate_refcount_tree(osb, first_blkno);
     if (!new_tree) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out_commit;
     }
 
     new_bh = sb_getblk(inode->i_sb, first_blkno);
     if (!new_bh) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out_commit;
     }
     ocfs2_set_new_buffer_uptodate(&new_tree->rf_ci, new_bh);
 
     ret = ocfs2_journal_access_rb(handle, &new_tree->rf_ci, new_bh,
                       OCFS2_JOURNAL_ACCESS_CREATE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     /* Initialize ocfs2_refcount_block. */
     rb = (struct ocfs2_refcount_block *)new_bh->b_data;
     memset(rb, 0, inode->i_sb->s_blocksize);
     strcpy((void *)rb, OCFS2_REFCOUNT_BLOCK_SIGNATURE);
     rb->rf_suballoc_slot = cpu_to_le16(meta_ac->ac_alloc_slot);
     rb->rf_suballoc_loc = cpu_to_le64(suballoc_loc);
     rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
     rb->rf_fs_generation = cpu_to_le32(osb->fs_generation);
     rb->rf_blkno = cpu_to_le64(first_blkno);
     rb->rf_count = cpu_to_le32(1);
     rb->rf_records.rl_count =
             cpu_to_le16(ocfs2_refcount_recs_per_rb(osb->sb));
     spin_lock(&osb->osb_lock);
     rb->rf_generation = osb->s_next_generation++;
     spin_unlock(&osb->osb_lock);
 
     ocfs2_journal_dirty(handle, new_bh);
 
     spin_lock(&oi->ip_lock);
     oi->ip_dyn_features |= OCFS2_HAS_REFCOUNT_FL;
     di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
     di->i_refcount_loc = cpu_to_le64(first_blkno);
     spin_unlock(&oi->ip_lock);
 
     trace_ocfs2_create_refcount_tree_blkno((unsigned long long)first_blkno);
 
     ocfs2_journal_dirty(handle, di_bh);
 
     /*
      * We have to init the tree lock here since it will use
      * the generation number to create it.
      */
     new_tree->rf_generation = le32_to_cpu(rb->rf_generation);
     ocfs2_init_refcount_tree_lock(osb, new_tree, first_blkno,
                       new_tree->rf_generation);
 
     spin_lock(&osb->osb_lock);
     tree = ocfs2_find_refcount_tree(osb, first_blkno);
 
     /*
      * We've just created a new refcount tree in this block.  If
      * we found a refcount tree on the ocfs2_super, it must be
      * one we just deleted.  We free the old tree before
      * inserting the new tree.
      */
     BUG_ON(tree && tree->rf_generation == new_tree->rf_generation);
     if (tree)
         ocfs2_erase_refcount_tree_from_list_no_lock(osb, tree);
     ocfs2_insert_refcount_tree(osb, new_tree);
     spin_unlock(&osb->osb_lock);
     new_tree = NULL;
     if (tree)
         ocfs2_refcount_tree_put(tree);
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 
 out:
     if (new_tree) {
         ocfs2_metadata_cache_exit(&new_tree->rf_ci);
         kfree(new_tree);
     }
 
     brelse(new_bh);
     if (meta_ac)
         ocfs2_free_alloc_context(meta_ac);
 
     return ret;
 }
 
 static int ocfs2_set_refcount_tree(struct inode *inode,
                    struct buffer_head *di_bh,
                    u64 refcount_loc)
 {
     int ret;
     handle_t *handle = NULL;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
     struct ocfs2_inode_info *oi = OCFS2_I(inode);
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_block *rb;
     struct ocfs2_refcount_tree *ref_tree;
 
     BUG_ON(ocfs2_is_refcount_inode(inode));
 
     ret = ocfs2_lock_refcount_tree(osb, refcount_loc, 1,
                        &ref_tree, &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         return ret;
     }
 
     handle = ocfs2_start_trans(osb, OCFS2_REFCOUNT_TREE_SET_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = ocfs2_journal_access_rb(handle, &ref_tree->rf_ci, ref_root_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     le32_add_cpu(&rb->rf_count, 1);
 
     ocfs2_journal_dirty(handle, ref_root_bh);
 
     spin_lock(&oi->ip_lock);
     oi->ip_dyn_features |= OCFS2_HAS_REFCOUNT_FL;
     di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
     di->i_refcount_loc = cpu_to_le64(refcount_loc);
     spin_unlock(&oi->ip_lock);
     ocfs2_journal_dirty(handle, di_bh);
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 out:
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     brelse(ref_root_bh);
 
     return ret;
 }
 
 int ocfs2_remove_refcount_tree(struct inode *inode, struct buffer_head *di_bh)
 {
     int ret, delete_tree = 0;
     handle_t *handle = NULL;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
     struct ocfs2_inode_info *oi = OCFS2_I(inode);
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct ocfs2_refcount_block *rb;
     struct inode *alloc_inode = NULL;
     struct buffer_head *alloc_bh = NULL;
     struct buffer_head *blk_bh = NULL;
     struct ocfs2_refcount_tree *ref_tree;
     int credits = OCFS2_REFCOUNT_TREE_REMOVE_CREDITS;
     u64 blk = 0, bg_blkno = 0, ref_blkno = le64_to_cpu(di->i_refcount_loc);
     u16 bit = 0;
 
     if (!ocfs2_is_refcount_inode(inode))
         return 0;
 
     BUG_ON(!ref_blkno);
     ret = ocfs2_lock_refcount_tree(osb, ref_blkno, 1, &ref_tree, &blk_bh);
     if (ret) {
         mlog_errno(ret);
         return ret;
     }
 
     rb = (struct ocfs2_refcount_block *)blk_bh->b_data;
 
     /*
      * If we are the last user, we need to free the block.
      * So lock the allocator ahead.
      */
     if (le32_to_cpu(rb->rf_count) == 1) {
         blk = le64_to_cpu(rb->rf_blkno);
         bit = le16_to_cpu(rb->rf_suballoc_bit);
         if (rb->rf_suballoc_loc)
             bg_blkno = le64_to_cpu(rb->rf_suballoc_loc);
         else
             bg_blkno = ocfs2_which_suballoc_group(blk, bit);
 
         alloc_inode = ocfs2_get_system_file_inode(osb,
                     EXTENT_ALLOC_SYSTEM_INODE,
                     le16_to_cpu(rb->rf_suballoc_slot));
         if (!alloc_inode) {
             ret = -ENOMEM;
             mlog_errno(ret);
             goto out;
         }
         inode_lock(alloc_inode);
 
         ret = ocfs2_inode_lock(alloc_inode, &alloc_bh, 1);
         if (ret) {
             mlog_errno(ret);
             goto out_mutex;
         }
 
         credits += OCFS2_SUBALLOC_FREE;
     }
 
     handle = ocfs2_start_trans(osb, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out_unlock;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = ocfs2_journal_access_rb(handle, &ref_tree->rf_ci, blk_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     spin_lock(&oi->ip_lock);
     oi->ip_dyn_features &= ~OCFS2_HAS_REFCOUNT_FL;
     di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
     di->i_refcount_loc = 0;
     spin_unlock(&oi->ip_lock);
     ocfs2_journal_dirty(handle, di_bh);
 
     le32_add_cpu(&rb->rf_count , -1);
     ocfs2_journal_dirty(handle, blk_bh);
 
     if (!rb->rf_count) {
         delete_tree = 1;
         ocfs2_erase_refcount_tree_from_list(osb, ref_tree);
         ret = ocfs2_free_suballoc_bits(handle, alloc_inode,
                            alloc_bh, bit, bg_blkno, 1);
         if (ret)
             mlog_errno(ret);
     }
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 out_unlock:
     if (alloc_inode) {
         ocfs2_inode_unlock(alloc_inode, 1);
         brelse(alloc_bh);
     }
 out_mutex:
     if (alloc_inode) {
         inode_unlock(alloc_inode);
         iput(alloc_inode);
     }
 out:
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     if (delete_tree)
         ocfs2_refcount_tree_put(ref_tree);
     brelse(blk_bh);
 
     return ret;
 }
 
 static void ocfs2_find_refcount_rec_in_rl(struct ocfs2_caching_info *ci,
                       struct buffer_head *ref_leaf_bh,
                       u64 cpos, unsigned int len,
                       struct ocfs2_refcount_rec *ret_rec,
                       int *index)
 {
     int i = 0;
     struct ocfs2_refcount_block *rb =
         (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_rec *rec = NULL;
 
     for (; i < le16_to_cpu(rb->rf_records.rl_used); i++) {
         rec = &rb->rf_records.rl_recs[i];
 
         if (le64_to_cpu(rec->r_cpos) +
             le32_to_cpu(rec->r_clusters) <= cpos)
             continue;
         else if (le64_to_cpu(rec->r_cpos) > cpos)
             break;
 
         /* ok, cpos fail in this rec. Just return. */
         if (ret_rec)
             *ret_rec = *rec;
         goto out;
     }
 
     if (ret_rec) {
         /* We meet with a hole here, so fake the rec. */
         ret_rec->r_cpos = cpu_to_le64(cpos);
         ret_rec->r_refcount = 0;
         if (i < le16_to_cpu(rb->rf_records.rl_used) &&
             le64_to_cpu(rec->r_cpos) < cpos + len)
             ret_rec->r_clusters =
                 cpu_to_le32(le64_to_cpu(rec->r_cpos) - cpos);
         else
             ret_rec->r_clusters = cpu_to_le32(len);
     }
 
 out:
     *index = i;
 }
 
 /*
  * Try to remove refcount tree. The mechanism is:
  * 1) Check whether i_clusters == 0, if no, exit.
  * 2) check whether we have i_xattr_loc in dinode. if yes, exit.
  * 3) Check whether we have inline xattr stored outside, if yes, exit.
  * 4) Remove the tree.
  */
 int ocfs2_try_remove_refcount_tree(struct inode *inode,
                    struct buffer_head *di_bh)
 {
     int ret;
     struct ocfs2_inode_info *oi = OCFS2_I(inode);
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
 
     down_write(&oi->ip_xattr_sem);
     down_write(&oi->ip_alloc_sem);
 
     if (oi->ip_clusters)
         goto out;
 
     if ((oi->ip_dyn_features & OCFS2_HAS_XATTR_FL) && di->i_xattr_loc)
         goto out;
 
     if (oi->ip_dyn_features & OCFS2_INLINE_XATTR_FL &&
         ocfs2_has_inline_xattr_value_outside(inode, di))
         goto out;
 
     ret = ocfs2_remove_refcount_tree(inode, di_bh);
     if (ret)
         mlog_errno(ret);
 out:
     up_write(&oi->ip_alloc_sem);
     up_write(&oi->ip_xattr_sem);
     return 0;
 }
 
 /*
  * Find the end range for a leaf refcount block indicated by
  * el->l_recs[index].e_blkno.
  */
 static int ocfs2_get_refcount_cpos_end(struct ocfs2_caching_info *ci,
                        struct buffer_head *ref_root_bh,
                        struct ocfs2_extent_block *eb,
                        struct ocfs2_extent_list *el,
                        int index,  u32 *cpos_end)
 {
     int ret, i, subtree_root;
     u32 cpos;
     u64 blkno;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct ocfs2_path *left_path = NULL, *right_path = NULL;
     struct ocfs2_extent_tree et;
     struct ocfs2_extent_list *tmp_el;
 
     if (index < le16_to_cpu(el->l_next_free_rec) - 1) {
         /*
          * We have a extent rec after index, so just use the e_cpos
          * of the next extent rec.
          */
         *cpos_end = le32_to_cpu(el->l_recs[index+1].e_cpos);
         return 0;
     }
 
     if (!eb || !eb->h_next_leaf_blk) {
         /*
          * We are the last extent rec, so any high cpos should
          * be stored in this leaf refcount block.
          */
         *cpos_end = UINT_MAX;
         return 0;
     }
 
     /*
      * If the extent block isn't the last one, we have to find
      * the subtree root between this extent block and the next
      * leaf extent block and get the corresponding e_cpos from
      * the subroot. Otherwise we may corrupt the b-tree.
      */
     ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
 
     left_path = ocfs2_new_path_from_et(&et);
     if (!left_path) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     cpos = le32_to_cpu(eb->h_list.l_recs[index].e_cpos);
     ret = ocfs2_find_path(ci, left_path, cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     right_path = ocfs2_new_path_from_path(left_path);
     if (!right_path) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_find_cpos_for_right_leaf(sb, left_path, &cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_find_path(ci, right_path, cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     subtree_root = ocfs2_find_subtree_root(&et, left_path,
                            right_path);
 
     tmp_el = left_path->p_node[subtree_root].el;
     blkno = left_path->p_node[subtree_root+1].bh->b_blocknr;
     for (i = 0; i < le16_to_cpu(tmp_el->l_next_free_rec); i++) {
         if (le64_to_cpu(tmp_el->l_recs[i].e_blkno) == blkno) {
             *cpos_end = le32_to_cpu(tmp_el->l_recs[i+1].e_cpos);
             break;
         }
     }
 
     BUG_ON(i == le16_to_cpu(tmp_el->l_next_free_rec));
 
 out:
     ocfs2_free_path(left_path);
     ocfs2_free_path(right_path);
     return ret;
 }
 
 /*
  * Given a cpos and len, try to find the refcount record which contains cpos.
  * 1. If cpos can be found in one refcount record, return the record.
  * 2. If cpos can't be found, return a fake record which start from cpos
  *    and end at a small value between cpos+len and start of the next record.
  *    This fake record has r_refcount = 0.
  */
 static int ocfs2_get_refcount_rec(struct ocfs2_caching_info *ci,
                   struct buffer_head *ref_root_bh,
                   u64 cpos, unsigned int len,
                   struct ocfs2_refcount_rec *ret_rec,
                   int *index,
                   struct buffer_head **ret_bh)
 {
     int ret = 0, i, found;
     u32 low_cpos, cpos_end;
     struct ocfs2_extent_list *el;
     struct ocfs2_extent_rec *rec = NULL;
     struct ocfs2_extent_block *eb = NULL;
     struct buffer_head *eb_bh = NULL, *ref_leaf_bh = NULL;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_root_bh->b_data;
 
     if (!(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL)) {
         ocfs2_find_refcount_rec_in_rl(ci, ref_root_bh, cpos, len,
                           ret_rec, index);
         *ret_bh = ref_root_bh;
         get_bh(ref_root_bh);
         return 0;
     }
 
     el = &rb->rf_list;
     low_cpos = cpos & OCFS2_32BIT_POS_MASK;
 
     if (el->l_tree_depth) {
         ret = ocfs2_find_leaf(ci, el, low_cpos, &eb_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         eb = (struct ocfs2_extent_block *) eb_bh->b_data;
         el = &eb->h_list;
 
         if (el->l_tree_depth) {
             ret = ocfs2_error(sb,
                       "refcount tree %llu has non zero tree depth in leaf btree tree block %llu\n",
                       (unsigned long long)ocfs2_metadata_cache_owner(ci),
                       (unsigned long long)eb_bh->b_blocknr);
             goto out;
         }
     }
 
     found = 0;
     for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
         rec = &el->l_recs[i];
 
         if (le32_to_cpu(rec->e_cpos) <= low_cpos) {
             found = 1;
             break;
         }
     }
 
     if (found) {
         ret = ocfs2_get_refcount_cpos_end(ci, ref_root_bh,
                           eb, el, i, &cpos_end);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         if (cpos_end < low_cpos + len)
             len = cpos_end - low_cpos;
     }
 
     ret = ocfs2_read_refcount_block(ci, le64_to_cpu(rec->e_blkno),
                     &ref_leaf_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ocfs2_find_refcount_rec_in_rl(ci, ref_leaf_bh, cpos, len,
                       ret_rec, index);
     *ret_bh = ref_leaf_bh;
 out:
     brelse(eb_bh);
     return ret;
 }
 
 enum ocfs2_ref_rec_contig {
     REF_CONTIG_NONE = 0,
     REF_CONTIG_LEFT,
     REF_CONTIG_RIGHT,
     REF_CONTIG_LEFTRIGHT,
 };
 
 static enum ocfs2_ref_rec_contig
     ocfs2_refcount_rec_adjacent(struct ocfs2_refcount_block *rb,
                     int index)
 {
     if ((rb->rf_records.rl_recs[index].r_refcount ==
         rb->rf_records.rl_recs[index + 1].r_refcount) &&
         (le64_to_cpu(rb->rf_records.rl_recs[index].r_cpos) +
         le32_to_cpu(rb->rf_records.rl_recs[index].r_clusters) ==
         le64_to_cpu(rb->rf_records.rl_recs[index + 1].r_cpos)))
         return REF_CONTIG_RIGHT;
 
     return REF_CONTIG_NONE;
 }
 
 static enum ocfs2_ref_rec_contig
     ocfs2_refcount_rec_contig(struct ocfs2_refcount_block *rb,
                   int index)
 {
     enum ocfs2_ref_rec_contig ret = REF_CONTIG_NONE;
 
     if (index < le16_to_cpu(rb->rf_records.rl_used) - 1)
         ret = ocfs2_refcount_rec_adjacent(rb, index);
 
     if (index > 0) {
         enum ocfs2_ref_rec_contig tmp;
 
         tmp = ocfs2_refcount_rec_adjacent(rb, index - 1);
 
         if (tmp == REF_CONTIG_RIGHT) {
             if (ret == REF_CONTIG_RIGHT)
                 ret = REF_CONTIG_LEFTRIGHT;
             else
                 ret = REF_CONTIG_LEFT;
         }
     }
 
     return ret;
 }
 
 static void ocfs2_rotate_refcount_rec_left(struct ocfs2_refcount_block *rb,
                        int index)
 {
     BUG_ON(rb->rf_records.rl_recs[index].r_refcount !=
            rb->rf_records.rl_recs[index+1].r_refcount);
 
     le32_add_cpu(&rb->rf_records.rl_recs[index].r_clusters,
              le32_to_cpu(rb->rf_records.rl_recs[index+1].r_clusters));
 
     if (index < le16_to_cpu(rb->rf_records.rl_used) - 2)
         memmove(&rb->rf_records.rl_recs[index + 1],
             &rb->rf_records.rl_recs[index + 2],
             sizeof(struct ocfs2_refcount_rec) *
             (le16_to_cpu(rb->rf_records.rl_used) - index - 2));
 
     memset(&rb->rf_records.rl_recs[le16_to_cpu(rb->rf_records.rl_used) - 1],
            0, sizeof(struct ocfs2_refcount_rec));
     le16_add_cpu(&rb->rf_records.rl_used, -1);
 }
 
 /*
  * Merge the refcount rec if we are contiguous with the adjacent recs.
  */
 static void ocfs2_refcount_rec_merge(struct ocfs2_refcount_block *rb,
                      int index)
 {
     enum ocfs2_ref_rec_contig contig =
                 ocfs2_refcount_rec_contig(rb, index);
 
     if (contig == REF_CONTIG_NONE)
         return;
 
     if (contig == REF_CONTIG_LEFT || contig == REF_CONTIG_LEFTRIGHT) {
         BUG_ON(index == 0);
         index--;
     }
 
     ocfs2_rotate_refcount_rec_left(rb, index);
 
     if (contig == REF_CONTIG_LEFTRIGHT)
         ocfs2_rotate_refcount_rec_left(rb, index);
 }
 
 /*
  * Change the refcount indexed by "index" in ref_bh.
  * If refcount reaches 0, remove it.
  */
 static int ocfs2_change_refcount_rec(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_leaf_bh,
                      int index, int merge, int change)
 {
     int ret;
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_list *rl = &rb->rf_records;
     struct ocfs2_refcount_rec *rec = &rl->rl_recs[index];
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_change_refcount_rec(
         (unsigned long long)ocfs2_metadata_cache_owner(ci),
         index, le32_to_cpu(rec->r_refcount), change);
     le32_add_cpu(&rec->r_refcount, change);
 
     if (!rec->r_refcount) {
         if (index != le16_to_cpu(rl->rl_used) - 1) {
             memmove(rec, rec + 1,
                 (le16_to_cpu(rl->rl_used) - index - 1) *
                 sizeof(struct ocfs2_refcount_rec));
             memset(&rl->rl_recs[le16_to_cpu(rl->rl_used) - 1],
                    0, sizeof(struct ocfs2_refcount_rec));
         }
 
         le16_add_cpu(&rl->rl_used, -1);
     } else if (merge)
         ocfs2_refcount_rec_merge(rb, index);
 
     ocfs2_journal_dirty(handle, ref_leaf_bh);
 out:
     return ret;
 }
 
 static int ocfs2_expand_inline_ref_root(handle_t *handle,
                     struct ocfs2_caching_info *ci,
                     struct buffer_head *ref_root_bh,
                     struct buffer_head **ref_leaf_bh,
                     struct ocfs2_alloc_context *meta_ac)
 {
     int ret;
     u16 suballoc_bit_start;
     u32 num_got;
     u64 suballoc_loc, blkno;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct buffer_head *new_bh = NULL;
     struct ocfs2_refcount_block *new_rb;
     struct ocfs2_refcount_block *root_rb =
             (struct ocfs2_refcount_block *)ref_root_bh->b_data;
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_claim_metadata(handle, meta_ac, 1, &suballoc_loc,
                    &suballoc_bit_start, &num_got,
                    &blkno);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     new_bh = sb_getblk(sb, blkno);
     if (new_bh == NULL) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
     ocfs2_set_new_buffer_uptodate(ci, new_bh);
 
     ret = ocfs2_journal_access_rb(handle, ci, new_bh,
                       OCFS2_JOURNAL_ACCESS_CREATE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     /*
      * Initialize ocfs2_refcount_block.
      * It should contain the same information as the old root.
      * so just memcpy it and change the corresponding field.
      */
     memcpy(new_bh->b_data, ref_root_bh->b_data, sb->s_blocksize);
 
     new_rb = (struct ocfs2_refcount_block *)new_bh->b_data;
     new_rb->rf_suballoc_slot = cpu_to_le16(meta_ac->ac_alloc_slot);
     new_rb->rf_suballoc_loc = cpu_to_le64(suballoc_loc);
     new_rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
     new_rb->rf_blkno = cpu_to_le64(blkno);
     new_rb->rf_cpos = cpu_to_le32(0);
     new_rb->rf_parent = cpu_to_le64(ref_root_bh->b_blocknr);
     new_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_LEAF_FL);
     ocfs2_journal_dirty(handle, new_bh);
 
     /* Now change the root. */
     memset(&root_rb->rf_list, 0, sb->s_blocksize -
            offsetof(struct ocfs2_refcount_block, rf_list));
     root_rb->rf_list.l_count = cpu_to_le16(ocfs2_extent_recs_per_rb(sb));
     root_rb->rf_clusters = cpu_to_le32(1);
     root_rb->rf_list.l_next_free_rec = cpu_to_le16(1);
     root_rb->rf_list.l_recs[0].e_blkno = cpu_to_le64(blkno);
     root_rb->rf_list.l_recs[0].e_leaf_clusters = cpu_to_le16(1);
     root_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_TREE_FL);
 
     ocfs2_journal_dirty(handle, ref_root_bh);
 
     trace_ocfs2_expand_inline_ref_root((unsigned long long)blkno,
         le16_to_cpu(new_rb->rf_records.rl_used));
 
     *ref_leaf_bh = new_bh;
     new_bh = NULL;
 out:
     brelse(new_bh);
     return ret;
 }
 
 static int ocfs2_refcount_rec_no_intersect(struct ocfs2_refcount_rec *prev,
                        struct ocfs2_refcount_rec *next)
 {
     if (ocfs2_get_ref_rec_low_cpos(prev) + le32_to_cpu(prev->r_clusters) <=
         ocfs2_get_ref_rec_low_cpos(next))
         return 1;
 
     return 0;
 }
 
 static int cmp_refcount_rec_by_low_cpos(const void *a, const void *b)
 {
     const struct ocfs2_refcount_rec *l = a, *r = b;
     u32 l_cpos = ocfs2_get_ref_rec_low_cpos(l);
     u32 r_cpos = ocfs2_get_ref_rec_low_cpos(r);
 
     if (l_cpos > r_cpos)
         return 1;
     if (l_cpos < r_cpos)
         return -1;
     return 0;
 }
 
 static int cmp_refcount_rec_by_cpos(const void *a, const void *b)
 {
     const struct ocfs2_refcount_rec *l = a, *r = b;
     u64 l_cpos = le64_to_cpu(l->r_cpos);
     u64 r_cpos = le64_to_cpu(r->r_cpos);
 
     if (l_cpos > r_cpos)
         return 1;
     if (l_cpos < r_cpos)
         return -1;
     return 0;
 }
 
 static void swap_refcount_rec(void *a, void *b, int size)
 {
     struct ocfs2_refcount_rec *l = a, *r = b;
 
     swap(*l, *r);
 }
 
 /*
  * The refcount cpos are ordered by their 64bit cpos,
  * But we will use the low 32 bit to be the e_cpos in the b-tree.
  * So we need to make sure that this pos isn't intersected with others.
  *
  * Note: The refcount block is already sorted by their low 32 bit cpos,
  *       So just try the middle pos first, and we will exit when we find
  *       the good position.
  */
 static int ocfs2_find_refcount_split_pos(struct ocfs2_refcount_list *rl,
                      u32 *split_pos, int *split_index)
 {
     int num_used = le16_to_cpu(rl->rl_used);
     int delta, middle = num_used / 2;
 
     for (delta = 0; delta < middle; delta++) {
         /* Let's check delta earlier than middle */
         if (ocfs2_refcount_rec_no_intersect(
                     &rl->rl_recs[middle - delta - 1],
                     &rl->rl_recs[middle - delta])) {
             *split_index = middle - delta;
             break;
         }
 
         /* For even counts, don't walk off the end */
         if ((middle + delta + 1) == num_used)
             continue;
 
         /* Now try delta past middle */
         if (ocfs2_refcount_rec_no_intersect(
                     &rl->rl_recs[middle + delta],
                     &rl->rl_recs[middle + delta + 1])) {
             *split_index = middle + delta + 1;
             break;
         }
     }
 
     if (delta >= middle)
         return -ENOSPC;
 
     *split_pos = ocfs2_get_ref_rec_low_cpos(&rl->rl_recs[*split_index]);
     return 0;
 }
 
 static int ocfs2_divide_leaf_refcount_block(struct buffer_head *ref_leaf_bh,
                         struct buffer_head *new_bh,
                         u32 *split_cpos)
 {
     int split_index = 0, num_moved, ret;
     u32 cpos = 0;
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_list *rl = &rb->rf_records;
     struct ocfs2_refcount_block *new_rb =
             (struct ocfs2_refcount_block *)new_bh->b_data;
     struct ocfs2_refcount_list *new_rl = &new_rb->rf_records;
 
     trace_ocfs2_divide_leaf_refcount_block(
         (unsigned long long)ref_leaf_bh->b_blocknr,
         le16_to_cpu(rl->rl_count), le16_to_cpu(rl->rl_used));
 
     /*
      * XXX: Improvement later.
      * If we know all the high 32 bit cpos is the same, no need to sort.
      *
      * In order to make the whole process safe, we do:
      * 1. sort the entries by their low 32 bit cpos first so that we can
      *    find the split cpos easily.
      * 2. call ocfs2_insert_extent to insert the new refcount block.
      * 3. move the refcount rec to the new block.
      * 4. sort the entries by their 64 bit cpos.
      * 5. dirty the new_rb and rb.
      */
     sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
          sizeof(struct ocfs2_refcount_rec),
          cmp_refcount_rec_by_low_cpos, swap_refcount_rec);
 
     ret = ocfs2_find_refcount_split_pos(rl, &cpos, &split_index);
     if (ret) {
         mlog_errno(ret);
         return ret;
     }
 
     new_rb->rf_cpos = cpu_to_le32(cpos);
 
     /* move refcount records starting from split_index to the new block. */
     num_moved = le16_to_cpu(rl->rl_used) - split_index;
     memcpy(new_rl->rl_recs, &rl->rl_recs[split_index],
            num_moved * sizeof(struct ocfs2_refcount_rec));
 
     /*ok, remove the entries we just moved over to the other block. */
     memset(&rl->rl_recs[split_index], 0,
            num_moved * sizeof(struct ocfs2_refcount_rec));
 
     /* change old and new rl_used accordingly. */
     le16_add_cpu(&rl->rl_used, -num_moved);
     new_rl->rl_used = cpu_to_le16(num_moved);
 
     sort(&rl->rl_recs, le16_to_cpu(rl->rl_used),
          sizeof(struct ocfs2_refcount_rec),
          cmp_refcount_rec_by_cpos, swap_refcount_rec);
 
     sort(&new_rl->rl_recs, le16_to_cpu(new_rl->rl_used),
          sizeof(struct ocfs2_refcount_rec),
          cmp_refcount_rec_by_cpos, swap_refcount_rec);
 
     *split_cpos = cpos;
     return 0;
 }
 
 static int ocfs2_new_leaf_refcount_block(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_root_bh,
                      struct buffer_head *ref_leaf_bh,
                      struct ocfs2_alloc_context *meta_ac)
 {
     int ret;
     u16 suballoc_bit_start;
     u32 num_got, new_cpos;
     u64 suballoc_loc, blkno;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct ocfs2_refcount_block *root_rb =
             (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     struct buffer_head *new_bh = NULL;
     struct ocfs2_refcount_block *new_rb;
     struct ocfs2_extent_tree ref_et;
 
     BUG_ON(!(le32_to_cpu(root_rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL));
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_claim_metadata(handle, meta_ac, 1, &suballoc_loc,
                    &suballoc_bit_start, &num_got,
                    &blkno);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     new_bh = sb_getblk(sb, blkno);
     if (new_bh == NULL) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
     ocfs2_set_new_buffer_uptodate(ci, new_bh);
 
     ret = ocfs2_journal_access_rb(handle, ci, new_bh,
                       OCFS2_JOURNAL_ACCESS_CREATE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     /* Initialize ocfs2_refcount_block. */
     new_rb = (struct ocfs2_refcount_block *)new_bh->b_data;
     memset(new_rb, 0, sb->s_blocksize);
     strcpy((void *)new_rb, OCFS2_REFCOUNT_BLOCK_SIGNATURE);
     new_rb->rf_suballoc_slot = cpu_to_le16(meta_ac->ac_alloc_slot);
     new_rb->rf_suballoc_loc = cpu_to_le64(suballoc_loc);
     new_rb->rf_suballoc_bit = cpu_to_le16(suballoc_bit_start);
     new_rb->rf_fs_generation = cpu_to_le32(OCFS2_SB(sb)->fs_generation);
     new_rb->rf_blkno = cpu_to_le64(blkno);
     new_rb->rf_parent = cpu_to_le64(ref_root_bh->b_blocknr);
     new_rb->rf_flags = cpu_to_le32(OCFS2_REFCOUNT_LEAF_FL);
     new_rb->rf_records.rl_count =
                 cpu_to_le16(ocfs2_refcount_recs_per_rb(sb));
     new_rb->rf_generation = root_rb->rf_generation;
 
     ret = ocfs2_divide_leaf_refcount_block(ref_leaf_bh, new_bh, &new_cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ocfs2_journal_dirty(handle, ref_leaf_bh);
     ocfs2_journal_dirty(handle, new_bh);
 
     ocfs2_init_refcount_extent_tree(&ref_et, ci, ref_root_bh);
 
     trace_ocfs2_new_leaf_refcount_block(
             (unsigned long long)new_bh->b_blocknr, new_cpos);
 
     /* Insert the new leaf block with the specific offset cpos. */
     ret = ocfs2_insert_extent(handle, &ref_et, new_cpos, new_bh->b_blocknr,
                   1, 0, meta_ac);
     if (ret)
         mlog_errno(ret);
 
 out:
     brelse(new_bh);
     return ret;
 }
 
 static int ocfs2_expand_refcount_tree(handle_t *handle,
                       struct ocfs2_caching_info *ci,
                       struct buffer_head *ref_root_bh,
                       struct buffer_head *ref_leaf_bh,
                       struct ocfs2_alloc_context *meta_ac)
 {
     int ret;
     struct buffer_head *expand_bh = NULL;
 
     if (ref_root_bh == ref_leaf_bh) {
         /*
          * the old root bh hasn't been expanded to a b-tree,
          * so expand it first.
          */
         ret = ocfs2_expand_inline_ref_root(handle, ci, ref_root_bh,
                            &expand_bh, meta_ac);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     } else {
         expand_bh = ref_leaf_bh;
         get_bh(expand_bh);
     }
 
 
     /* Now add a new refcount block into the tree.*/
     ret = ocfs2_new_leaf_refcount_block(handle, ci, ref_root_bh,
                         expand_bh, meta_ac);
     if (ret)
         mlog_errno(ret);
 out:
     brelse(expand_bh);
     return ret;
 }
 
 /*
  * Adjust the extent rec in b-tree representing ref_leaf_bh.
  *
  * Only called when we have inserted a new refcount rec at index 0
  * which means ocfs2_extent_rec.e_cpos may need some change.
  */
 static int ocfs2_adjust_refcount_rec(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_root_bh,
                      struct buffer_head *ref_leaf_bh,
                      struct ocfs2_refcount_rec *rec)
 {
     int ret = 0, i;
     u32 new_cpos, old_cpos;
     struct ocfs2_path *path = NULL;
     struct ocfs2_extent_tree et;
     struct ocfs2_refcount_block *rb =
         (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     struct ocfs2_extent_list *el;
 
     if (!(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL))
         goto out;
 
     rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     old_cpos = le32_to_cpu(rb->rf_cpos);
     new_cpos = le64_to_cpu(rec->r_cpos) & OCFS2_32BIT_POS_MASK;
     if (old_cpos <= new_cpos)
         goto out;
 
     ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
 
     path = ocfs2_new_path_from_et(&et);
     if (!path) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_find_path(ci, path, old_cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     /*
      * 2 more credits, one for the leaf refcount block, one for
      * the extent block contains the extent rec.
      */
     ret = ocfs2_extend_trans(handle, 2);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_eb(handle, ci, path_leaf_bh(path),
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
     /* change the leaf extent block first. */
     el = path_leaf_el(path);
 
     for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++)
         if (le32_to_cpu(el->l_recs[i].e_cpos) == old_cpos)
             break;
 
     BUG_ON(i == le16_to_cpu(el->l_next_free_rec));
 
     el->l_recs[i].e_cpos = cpu_to_le32(new_cpos);
 
     /* change the r_cpos in the leaf block. */
     rb->rf_cpos = cpu_to_le32(new_cpos);
 
     ocfs2_journal_dirty(handle, path_leaf_bh(path));
     ocfs2_journal_dirty(handle, ref_leaf_bh);
 
 out:
     ocfs2_free_path(path);
     return ret;
 }
 
 static int ocfs2_insert_refcount_rec(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_root_bh,
                      struct buffer_head *ref_leaf_bh,
                      struct ocfs2_refcount_rec *rec,
                      int index, int merge,
                      struct ocfs2_alloc_context *meta_ac)
 {
     int ret;
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_list *rf_list = &rb->rf_records;
     struct buffer_head *new_bh = NULL;
 
     BUG_ON(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL);
 
     if (rf_list->rl_used == rf_list->rl_count) {
         u64 cpos = le64_to_cpu(rec->r_cpos);
         u32 len = le32_to_cpu(rec->r_clusters);
 
         ret = ocfs2_expand_refcount_tree(handle, ci, ref_root_bh,
                          ref_leaf_bh, meta_ac);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                          cpos, len, NULL, &index,
                          &new_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         ref_leaf_bh = new_bh;
         rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
         rf_list = &rb->rf_records;
     }
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     if (index < le16_to_cpu(rf_list->rl_used))
         memmove(&rf_list->rl_recs[index + 1],
             &rf_list->rl_recs[index],
             (le16_to_cpu(rf_list->rl_used) - index) *
              sizeof(struct ocfs2_refcount_rec));
 
     trace_ocfs2_insert_refcount_rec(
         (unsigned long long)ref_leaf_bh->b_blocknr, index,
         (unsigned long long)le64_to_cpu(rec->r_cpos),
         le32_to_cpu(rec->r_clusters), le32_to_cpu(rec->r_refcount));
 
     rf_list->rl_recs[index] = *rec;
 
     le16_add_cpu(&rf_list->rl_used, 1);
 
     if (merge)
         ocfs2_refcount_rec_merge(rb, index);
 
     ocfs2_journal_dirty(handle, ref_leaf_bh);
 
     if (index == 0) {
         ret = ocfs2_adjust_refcount_rec(handle, ci,
                         ref_root_bh,
                         ref_leaf_bh, rec);
         if (ret)
             mlog_errno(ret);
     }
 out:
     brelse(new_bh);
     return ret;
 }
 
 /*
  * Split the refcount_rec indexed by "index" in ref_leaf_bh.
  * This is much simple than our b-tree code.
  * split_rec is the new refcount rec we want to insert.
  * If split_rec->r_refcount > 0, we are changing the refcount(in case we
  * increase refcount or decrease a refcount to non-zero).
  * If split_rec->r_refcount == 0, we are punching a hole in current refcount
  * rec( in case we decrease a refcount to zero).
  */
 static int ocfs2_split_refcount_rec(handle_t *handle,
                     struct ocfs2_caching_info *ci,
                     struct buffer_head *ref_root_bh,
                     struct buffer_head *ref_leaf_bh,
                     struct ocfs2_refcount_rec *split_rec,
                     int index, int merge,
                     struct ocfs2_alloc_context *meta_ac,
                     struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret, recs_need;
     u32 len;
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_list *rf_list = &rb->rf_records;
     struct ocfs2_refcount_rec *orig_rec = &rf_list->rl_recs[index];
     struct ocfs2_refcount_rec *tail_rec = NULL;
     struct buffer_head *new_bh = NULL;
 
     BUG_ON(le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL);
 
     trace_ocfs2_split_refcount_rec(le64_to_cpu(orig_rec->r_cpos),
         le32_to_cpu(orig_rec->r_clusters),
         le32_to_cpu(orig_rec->r_refcount),
         le64_to_cpu(split_rec->r_cpos),
         le32_to_cpu(split_rec->r_clusters),
         le32_to_cpu(split_rec->r_refcount));
 
     /*
      * If we just need to split the header or tail clusters,
      * no more recs are needed, just split is OK.
      * Otherwise we at least need one new recs.
      */
     if (!split_rec->r_refcount &&
         (split_rec->r_cpos == orig_rec->r_cpos ||
          le64_to_cpu(split_rec->r_cpos) +
          le32_to_cpu(split_rec->r_clusters) ==
          le64_to_cpu(orig_rec->r_cpos) + le32_to_cpu(orig_rec->r_clusters)))
         recs_need = 0;
     else
         recs_need = 1;
 
     /*
      * We need one more rec if we split in the middle and the new rec have
      * some refcount in it.
      */
     if (split_rec->r_refcount &&
         (split_rec->r_cpos != orig_rec->r_cpos &&
          le64_to_cpu(split_rec->r_cpos) +
          le32_to_cpu(split_rec->r_clusters) !=
          le64_to_cpu(orig_rec->r_cpos) + le32_to_cpu(orig_rec->r_clusters)))
         recs_need++;
 
     /* If the leaf block don't have enough record, expand it. */
     if (le16_to_cpu(rf_list->rl_used) + recs_need >
                      le16_to_cpu(rf_list->rl_count)) {
         struct ocfs2_refcount_rec tmp_rec;
         u64 cpos = le64_to_cpu(orig_rec->r_cpos);
         len = le32_to_cpu(orig_rec->r_clusters);
         ret = ocfs2_expand_refcount_tree(handle, ci, ref_root_bh,
                          ref_leaf_bh, meta_ac);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         /*
          * We have to re-get it since now cpos may be moved to
          * another leaf block.
          */
         ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                          cpos, len, &tmp_rec, &index,
                          &new_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         ref_leaf_bh = new_bh;
         rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
         rf_list = &rb->rf_records;
         orig_rec = &rf_list->rl_recs[index];
     }
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     /*
      * We have calculated out how many new records we need and store
      * in recs_need, so spare enough space first by moving the records
      * after "index" to the end.
      */
     if (index != le16_to_cpu(rf_list->rl_used) - 1)
         memmove(&rf_list->rl_recs[index + 1 + recs_need],
             &rf_list->rl_recs[index + 1],
             (le16_to_cpu(rf_list->rl_used) - index - 1) *
              sizeof(struct ocfs2_refcount_rec));
 
     len = (le64_to_cpu(orig_rec->r_cpos) +
           le32_to_cpu(orig_rec->r_clusters)) -
           (le64_to_cpu(split_rec->r_cpos) +
           le32_to_cpu(split_rec->r_clusters));
 
     /*
      * If we have "len", the we will split in the tail and move it
      * to the end of the space we have just spared.
      */
     if (len) {
         tail_rec = &rf_list->rl_recs[index + recs_need];
 
         memcpy(tail_rec, orig_rec, sizeof(struct ocfs2_refcount_rec));
         le64_add_cpu(&tail_rec->r_cpos,
                  le32_to_cpu(tail_rec->r_clusters) - len);
         tail_rec->r_clusters = cpu_to_le32(len);
     }
 
     /*
      * If the split pos isn't the same as the original one, we need to
      * split in the head.
      *
      * Note: We have the chance that split_rec.r_refcount = 0,
      * recs_need = 0 and len > 0, which means we just cut the head from
      * the orig_rec and in that case we have done some modification in
      * orig_rec above, so the check for r_cpos is faked.
      */
     if (split_rec->r_cpos != orig_rec->r_cpos && tail_rec != orig_rec) {
         len = le64_to_cpu(split_rec->r_cpos) -
               le64_to_cpu(orig_rec->r_cpos);
         orig_rec->r_clusters = cpu_to_le32(len);
         index++;
     }
 
     le16_add_cpu(&rf_list->rl_used, recs_need);
 
     if (split_rec->r_refcount) {
         rf_list->rl_recs[index] = *split_rec;
         trace_ocfs2_split_refcount_rec_insert(
             (unsigned long long)ref_leaf_bh->b_blocknr, index,
             (unsigned long long)le64_to_cpu(split_rec->r_cpos),
             le32_to_cpu(split_rec->r_clusters),
             le32_to_cpu(split_rec->r_refcount));
 
         if (merge)
             ocfs2_refcount_rec_merge(rb, index);
     }
 
     ocfs2_journal_dirty(handle, ref_leaf_bh);
 
 out:
     brelse(new_bh);
     return ret;
 }
 
 static int __ocfs2_increase_refcount(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_root_bh,
                      u64 cpos, u32 len, int merge,
                      struct ocfs2_alloc_context *meta_ac,
                      struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret = 0, index;
     struct buffer_head *ref_leaf_bh = NULL;
     struct ocfs2_refcount_rec rec;
     unsigned int set_len = 0;
 
     trace_ocfs2_increase_refcount_begin(
          (unsigned long long)ocfs2_metadata_cache_owner(ci),
          (unsigned long long)cpos, len);
 
     while (len) {
         ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                          cpos, len, &rec, &index,
                          &ref_leaf_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         set_len = le32_to_cpu(rec.r_clusters);
 
         /*
          * Here we may meet with 3 situations:
          *
          * 1. If we find an already existing record, and the length
          *    is the same, cool, we just need to increase the r_refcount
          *    and it is OK.
          * 2. If we find a hole, just insert it with r_refcount = 1.
          * 3. If we are in the middle of one extent record, split
          *    it.
          */
         if (rec.r_refcount && le64_to_cpu(rec.r_cpos) == cpos &&
             set_len <= len) {
             trace_ocfs2_increase_refcount_change(
                 (unsigned long long)cpos, set_len,
                 le32_to_cpu(rec.r_refcount));
             ret = ocfs2_change_refcount_rec(handle, ci,
                             ref_leaf_bh, index,
                             merge, 1);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
         } else if (!rec.r_refcount) {
             rec.r_refcount = cpu_to_le32(1);
 
             trace_ocfs2_increase_refcount_insert(
                  (unsigned long long)le64_to_cpu(rec.r_cpos),
                  set_len);
             ret = ocfs2_insert_refcount_rec(handle, ci, ref_root_bh,
                             ref_leaf_bh,
                             &rec, index,
                             merge, meta_ac);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
         } else  {
             set_len = min((u64)(cpos + len),
                       le64_to_cpu(rec.r_cpos) + set_len) - cpos;
             rec.r_cpos = cpu_to_le64(cpos);
             rec.r_clusters = cpu_to_le32(set_len);
             le32_add_cpu(&rec.r_refcount, 1);
 
             trace_ocfs2_increase_refcount_split(
                  (unsigned long long)le64_to_cpu(rec.r_cpos),
                  set_len, le32_to_cpu(rec.r_refcount));
             ret = ocfs2_split_refcount_rec(handle, ci,
                                ref_root_bh, ref_leaf_bh,
                                &rec, index, merge,
                                meta_ac, dealloc);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
         }
 
         cpos += set_len;
         len -= set_len;
         brelse(ref_leaf_bh);
         ref_leaf_bh = NULL;
     }
 
 out:
     brelse(ref_leaf_bh);
     return ret;
 }
 
 static int ocfs2_remove_refcount_extent(handle_t *handle,
                 struct ocfs2_caching_info *ci,
                 struct buffer_head *ref_root_bh,
                 struct buffer_head *ref_leaf_bh,
                 struct ocfs2_alloc_context *meta_ac,
                 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_extent_tree et;
 
     BUG_ON(rb->rf_records.rl_used);
 
     trace_ocfs2_remove_refcount_extent(
         (unsigned long long)ocfs2_metadata_cache_owner(ci),
         (unsigned long long)ref_leaf_bh->b_blocknr,
         le32_to_cpu(rb->rf_cpos));
 
     ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
     ret = ocfs2_remove_extent(handle, &et, le32_to_cpu(rb->rf_cpos),
                   1, meta_ac, dealloc);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ocfs2_remove_from_cache(ci, ref_leaf_bh);
 
     /*
      * add the freed block to the dealloc so that it will be freed
      * when we run dealloc.
      */
     ret = ocfs2_cache_block_dealloc(dealloc, EXTENT_ALLOC_SYSTEM_INODE,
                     le16_to_cpu(rb->rf_suballoc_slot),
                     le64_to_cpu(rb->rf_suballoc_loc),
                     le64_to_cpu(rb->rf_blkno),
                     le16_to_cpu(rb->rf_suballoc_bit));
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
 
     le32_add_cpu(&rb->rf_clusters, -1);
 
     /*
      * check whether we need to restore the root refcount block if
      * there is no leaf extent block at atll.
      */
     if (!rb->rf_list.l_next_free_rec) {
         BUG_ON(rb->rf_clusters);
 
         trace_ocfs2_restore_refcount_block(
              (unsigned long long)ref_root_bh->b_blocknr);
 
         rb->rf_flags = 0;
         rb->rf_parent = 0;
         rb->rf_cpos = 0;
         memset(&rb->rf_records, 0, sb->s_blocksize -
                offsetof(struct ocfs2_refcount_block, rf_records));
         rb->rf_records.rl_count =
                 cpu_to_le16(ocfs2_refcount_recs_per_rb(sb));
     }
 
     ocfs2_journal_dirty(handle, ref_root_bh);
 
 out:
     return ret;
 }
 
 int ocfs2_increase_refcount(handle_t *handle,
                 struct ocfs2_caching_info *ci,
                 struct buffer_head *ref_root_bh,
                 u64 cpos, u32 len,
                 struct ocfs2_alloc_context *meta_ac,
                 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     return __ocfs2_increase_refcount(handle, ci, ref_root_bh,
                      cpos, len, 1,
                      meta_ac, dealloc);
 }
 
 static int ocfs2_decrease_refcount_rec(handle_t *handle,
                 struct ocfs2_caching_info *ci,
                 struct buffer_head *ref_root_bh,
                 struct buffer_head *ref_leaf_bh,
                 int index, u64 cpos, unsigned int len,
                 struct ocfs2_alloc_context *meta_ac,
                 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret;
     struct ocfs2_refcount_block *rb =
             (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
     struct ocfs2_refcount_rec *rec = &rb->rf_records.rl_recs[index];
 
     BUG_ON(cpos < le64_to_cpu(rec->r_cpos));
     BUG_ON(cpos + len >
            le64_to_cpu(rec->r_cpos) + le32_to_cpu(rec->r_clusters));
 
     trace_ocfs2_decrease_refcount_rec(
         (unsigned long long)ocfs2_metadata_cache_owner(ci),
         (unsigned long long)cpos, len);
 
     if (cpos == le64_to_cpu(rec->r_cpos) &&
         len == le32_to_cpu(rec->r_clusters))
         ret = ocfs2_change_refcount_rec(handle, ci,
                         ref_leaf_bh, index, 1, -1);
     else {
         struct ocfs2_refcount_rec split = *rec;
         split.r_cpos = cpu_to_le64(cpos);
         split.r_clusters = cpu_to_le32(len);
 
         le32_add_cpu(&split.r_refcount, -1);
 
         ret = ocfs2_split_refcount_rec(handle, ci,
                            ref_root_bh, ref_leaf_bh,
                            &split, index, 1,
                            meta_ac, dealloc);
     }
 
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     /* Remove the leaf refcount block if it contains no refcount record. */
     if (!rb->rf_records.rl_used && ref_leaf_bh != ref_root_bh) {
         ret = ocfs2_remove_refcount_extent(handle, ci, ref_root_bh,
                            ref_leaf_bh, meta_ac,
                            dealloc);
         if (ret)
             mlog_errno(ret);
     }
 
 out:
     return ret;
 }
 
 static int __ocfs2_decrease_refcount(handle_t *handle,
                      struct ocfs2_caching_info *ci,
                      struct buffer_head *ref_root_bh,
                      u64 cpos, u32 len,
                      struct ocfs2_alloc_context *meta_ac,
                      struct ocfs2_cached_dealloc_ctxt *dealloc,
                      int delete)
 {
     int ret = 0, index = 0;
     struct ocfs2_refcount_rec rec;
     unsigned int r_count = 0, r_len;
     struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
     struct buffer_head *ref_leaf_bh = NULL;
 
     trace_ocfs2_decrease_refcount(
         (unsigned long long)ocfs2_metadata_cache_owner(ci),
         (unsigned long long)cpos, len, delete);
 
     while (len) {
         ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                          cpos, len, &rec, &index,
                          &ref_leaf_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         r_count = le32_to_cpu(rec.r_refcount);
         BUG_ON(r_count == 0);
         if (!delete)
             BUG_ON(r_count > 1);
 
         r_len = min((u64)(cpos + len), le64_to_cpu(rec.r_cpos) +
                   le32_to_cpu(rec.r_clusters)) - cpos;
 
         ret = ocfs2_decrease_refcount_rec(handle, ci, ref_root_bh,
                           ref_leaf_bh, index,
                           cpos, r_len,
                           meta_ac, dealloc);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         if (le32_to_cpu(rec.r_refcount) == 1 && delete) {
             ret = ocfs2_cache_cluster_dealloc(dealloc,
                       ocfs2_clusters_to_blocks(sb, cpos),
                               r_len);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
         }
 
         cpos += r_len;
         len -= r_len;
         brelse(ref_leaf_bh);
         ref_leaf_bh = NULL;
     }
 
 out:
     brelse(ref_leaf_bh);
     return ret;
 }
 
 /* Caller must hold refcount tree lock. */
 int ocfs2_decrease_refcount(struct inode *inode,
                 handle_t *handle, u32 cpos, u32 len,
                 struct ocfs2_alloc_context *meta_ac,
                 struct ocfs2_cached_dealloc_ctxt *dealloc,
                 int delete)
 {
     int ret;
     u64 ref_blkno;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_tree *tree;
 
     BUG_ON(!ocfs2_is_refcount_inode(inode));
 
     ret = ocfs2_get_refcount_block(inode, &ref_blkno);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb), ref_blkno, &tree);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_read_refcount_block(&tree->rf_ci, tree->rf_blkno,
                     &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = __ocfs2_decrease_refcount(handle, &tree->rf_ci, ref_root_bh,
                     cpos, len, meta_ac, dealloc, delete);
     if (ret)
         mlog_errno(ret);
 out:
     brelse(ref_root_bh);
     return ret;
 }
 
 /*
  * Mark the already-existing extent at cpos as refcounted for len clusters.
  * This adds the refcount extent flag.
  *
  * If the existing extent is larger than the request, initiate a
  * split. An attempt will be made at merging with adjacent extents.
  *
  * The caller is responsible for passing down meta_ac if we'll need it.
  */
 static int ocfs2_mark_extent_refcounted(struct inode *inode,
                 struct ocfs2_extent_tree *et,
                 handle_t *handle, u32 cpos,
                 u32 len, u32 phys,
                 struct ocfs2_alloc_context *meta_ac,
                 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret;
 
     trace_ocfs2_mark_extent_refcounted(OCFS2_I(inode)->ip_blkno,
                        cpos, len, phys);
 
     if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb))) {
         ret = ocfs2_error(inode->i_sb, "Inode %lu want to use refcount tree, but the feature bit is not set in the super block\n",
                   inode->i_ino);
         goto out;
     }
 
     ret = ocfs2_change_extent_flag(handle, et, cpos,
                        len, phys, meta_ac, dealloc,
                        OCFS2_EXT_REFCOUNTED, 0);
     if (ret)
         mlog_errno(ret);
 
 out:
     return ret;
 }
 
 /*
  * Given some contiguous physical clusters, calculate what we need
  * for modifying their refcount.
  */
 static int ocfs2_calc_refcount_meta_credits(struct super_block *sb,
                         struct ocfs2_caching_info *ci,
                         struct buffer_head *ref_root_bh,
                         u64 start_cpos,
                         u32 clusters,
                         int *meta_add,
                         int *credits)
 {
     int ret = 0, index, ref_blocks = 0, recs_add = 0;
     u64 cpos = start_cpos;
     struct ocfs2_refcount_block *rb;
     struct ocfs2_refcount_rec rec;
     struct buffer_head *ref_leaf_bh = NULL, *prev_bh = NULL;
     u32 len;
 
     while (clusters) {
         ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
                          cpos, clusters, &rec,
                          &index, &ref_leaf_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         if (ref_leaf_bh != prev_bh) {
             /*
              * Now we encounter a new leaf block, so calculate
              * whether we need to extend the old leaf.
              */
             if (prev_bh) {
                 rb = (struct ocfs2_refcount_block *)
                             prev_bh->b_data;
 
                 if (le16_to_cpu(rb->rf_records.rl_used) +
                     recs_add >
                     le16_to_cpu(rb->rf_records.rl_count))
                     ref_blocks++;
             }
 
             recs_add = 0;
             *credits += 1;
             brelse(prev_bh);
             prev_bh = ref_leaf_bh;
             get_bh(prev_bh);
         }
 
         trace_ocfs2_calc_refcount_meta_credits_iterate(
                 recs_add, (unsigned long long)cpos, clusters,
                 (unsigned long long)le64_to_cpu(rec.r_cpos),
                 le32_to_cpu(rec.r_clusters),
                 le32_to_cpu(rec.r_refcount), index);
 
         len = min((u64)cpos + clusters, le64_to_cpu(rec.r_cpos) +
               le32_to_cpu(rec.r_clusters)) - cpos;
         /*
          * We record all the records which will be inserted to the
          * same refcount block, so that we can tell exactly whether
          * we need a new refcount block or not.
          *
          * If we will insert a new one, this is easy and only happens
          * during adding refcounted flag to the extent, so we don't
          * have a chance of spliting. We just need one record.
          *
          * If the refcount rec already exists, that would be a little
          * complicated. we may have to:
          * 1) split at the beginning if the start pos isn't aligned.
          *    we need 1 more record in this case.
          * 2) split int the end if the end pos isn't aligned.
          *    we need 1 more record in this case.
          * 3) split in the middle because of file system fragmentation.
          *    we need 2 more records in this case(we can't detect this
          *    beforehand, so always think of the worst case).
          */
         if (rec.r_refcount) {
             recs_add += 2;
             /* Check whether we need a split at the beginning. */
             if (cpos == start_cpos &&
                 cpos != le64_to_cpu(rec.r_cpos))
                 recs_add++;
 
             /* Check whether we need a split in the end. */
             if (cpos + clusters < le64_to_cpu(rec.r_cpos) +
                 le32_to_cpu(rec.r_clusters))
                 recs_add++;
         } else
             recs_add++;
 
         brelse(ref_leaf_bh);
         ref_leaf_bh = NULL;
         clusters -= len;
         cpos += len;
     }
 
     if (prev_bh) {
         rb = (struct ocfs2_refcount_block *)prev_bh->b_data;
 
         if (le16_to_cpu(rb->rf_records.rl_used) + recs_add >
             le16_to_cpu(rb->rf_records.rl_count))
             ref_blocks++;
 
         *credits += 1;
     }
 
     if (!ref_blocks)
         goto out;
 
     *meta_add += ref_blocks;
     *credits += ref_blocks;
 
     /*
      * So we may need ref_blocks to insert into the tree.
      * That also means we need to change the b-tree and add that number
      * of records since we never merge them.
      * We need one more block for expansion since the new created leaf
      * block is also full and needs split.
      */
     rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     if (le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL) {
         struct ocfs2_extent_tree et;
 
         ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
         *meta_add += ocfs2_extend_meta_needed(et.et_root_el);
         *credits += ocfs2_calc_extend_credits(sb,
                               et.et_root_el);
     } else {
         *credits += OCFS2_EXPAND_REFCOUNT_TREE_CREDITS;
         *meta_add += 1;
     }
 
 out:
 
     trace_ocfs2_calc_refcount_meta_credits(
         (unsigned long long)start_cpos, clusters,
         *meta_add, *credits);
     brelse(ref_leaf_bh);
     brelse(prev_bh);
     return ret;
 }
 
 /*
  * For refcount tree, we will decrease some contiguous clusters
  * refcount count, so just go through it to see how many blocks
  * we gonna touch and whether we need to create new blocks.
  *
  * Normally the refcount blocks store these refcount should be
  * contiguous also, so that we can get the number easily.
  * We will at most add split 2 refcount records and 2 more
  * refcount blocks, so just check it in a rough way.
  *
  * Caller must hold refcount tree lock.
  */
 int ocfs2_prepare_refcount_change_for_del(struct inode *inode,
                       u64 refcount_loc,
                       u64 phys_blkno,
                       u32 clusters,
                       int *credits,
                       int *ref_blocks)
 {
     int ret;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_tree *tree;
     u64 start_cpos = ocfs2_blocks_to_clusters(inode->i_sb, phys_blkno);
 
     if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb))) {
         ret = ocfs2_error(inode->i_sb, "Inode %lu want to use refcount tree, but the feature bit is not set in the super block\n",
                   inode->i_ino);
         goto out;
     }
 
     BUG_ON(!ocfs2_is_refcount_inode(inode));
 
     ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb),
                       refcount_loc, &tree);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_read_refcount_block(&tree->rf_ci, refcount_loc,
                     &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_calc_refcount_meta_credits(inode->i_sb,
                            &tree->rf_ci,
                            ref_root_bh,
                            start_cpos, clusters,
                            ref_blocks, credits);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_prepare_refcount_change_for_del(*ref_blocks, *credits);
 
 out:
     brelse(ref_root_bh);
     return ret;
 }
 
 #define MAX_CONTIG_BYTES    1048576
 
 static inline unsigned int ocfs2_cow_contig_clusters(struct super_block *sb)
 {
     return ocfs2_clusters_for_bytes(sb, MAX_CONTIG_BYTES);
 }
 
 static inline unsigned int ocfs2_cow_contig_mask(struct super_block *sb)
 {
     return ~(ocfs2_cow_contig_clusters(sb) - 1);
 }
 
 /*
  * Given an extent that starts at 'start' and an I/O that starts at 'cpos',
  * find an offset (start + (n * contig_clusters)) that is closest to cpos
  * while still being less than or equal to it.
  *
  * The goal is to break the extent at a multiple of contig_clusters.
  */
 static inline unsigned int ocfs2_cow_align_start(struct super_block *sb,
                          unsigned int start,
                          unsigned int cpos)
 {
     BUG_ON(start > cpos);
 
     return start + ((cpos - start) & ocfs2_cow_contig_mask(sb));
 }
 
 /*
  * Given a cluster count of len, pad it out so that it is a multiple
  * of contig_clusters.
  */
 static inline unsigned int ocfs2_cow_align_length(struct super_block *sb,
                           unsigned int len)
 {
     unsigned int padded =
         (len + (ocfs2_cow_contig_clusters(sb) - 1)) &
         ocfs2_cow_contig_mask(sb);
 
     /* Did we wrap? */
     if (padded < len)
         padded = UINT_MAX;
 
     return padded;
 }
 
 /*
  * Calculate out the start and number of virtual clusters we need to to CoW.
  *
  * cpos is vitual start cluster position we want to do CoW in a
  * file and write_len is the cluster length.
  * max_cpos is the place where we want to stop CoW intentionally.
  *
  * Normal we will start CoW from the beginning of extent record cotaining cpos.
  * We try to break up extents on boundaries of MAX_CONTIG_BYTES so that we
  * get good I/O from the resulting extent tree.
  */
 static int ocfs2_refcount_cal_cow_clusters(struct inode *inode,
                        struct ocfs2_extent_list *el,
                        u32 cpos,
                        u32 write_len,
                        u32 max_cpos,
                        u32 *cow_start,
                        u32 *cow_len)
 {
     int ret = 0;
     int tree_height = le16_to_cpu(el->l_tree_depth), i;
     struct buffer_head *eb_bh = NULL;
     struct ocfs2_extent_block *eb = NULL;
     struct ocfs2_extent_rec *rec;
     unsigned int want_clusters, rec_end = 0;
     int contig_clusters = ocfs2_cow_contig_clusters(inode->i_sb);
     int leaf_clusters;
 
     BUG_ON(cpos + write_len > max_cpos);
 
     if (tree_height > 0) {
         ret = ocfs2_find_leaf(INODE_CACHE(inode), el, cpos, &eb_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         eb = (struct ocfs2_extent_block *) eb_bh->b_data;
         el = &eb->h_list;
 
         if (el->l_tree_depth) {
             ret = ocfs2_error(inode->i_sb,
                       "Inode %lu has non zero tree depth in leaf block %llu\n",
                       inode->i_ino,
                       (unsigned long long)eb_bh->b_blocknr);
             goto out;
         }
     }
 
     *cow_len = 0;
     for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
         rec = &el->l_recs[i];
 
         if (ocfs2_is_empty_extent(rec)) {
             mlog_bug_on_msg(i != 0, "Inode %lu has empty record in "
                     "index %d\n", inode->i_ino, i);
             continue;
         }
 
         if (le32_to_cpu(rec->e_cpos) +
             le16_to_cpu(rec->e_leaf_clusters) <= cpos)
             continue;
 
         if (*cow_len == 0) {
             /*
              * We should find a refcounted record in the
              * first pass.
              */
             BUG_ON(!(rec->e_flags & OCFS2_EXT_REFCOUNTED));
             *cow_start = le32_to_cpu(rec->e_cpos);
         }
 
         /*
          * If we encounter a hole, a non-refcounted record or
          * pass the max_cpos, stop the search.
          */
         if ((!(rec->e_flags & OCFS2_EXT_REFCOUNTED)) ||
             (*cow_len && rec_end != le32_to_cpu(rec->e_cpos)) ||
             (max_cpos <= le32_to_cpu(rec->e_cpos)))
             break;
 
         leaf_clusters = le16_to_cpu(rec->e_leaf_clusters);
         rec_end = le32_to_cpu(rec->e_cpos) + leaf_clusters;
         if (rec_end > max_cpos) {
             rec_end = max_cpos;
             leaf_clusters = rec_end - le32_to_cpu(rec->e_cpos);
         }
 
         /*
          * How many clusters do we actually need from
          * this extent?  First we see how many we actually
          * need to complete the write.  If that's smaller
          * than contig_clusters, we try for contig_clusters.
          */
         if (!*cow_len)
             want_clusters = write_len;
         else
             want_clusters = (cpos + write_len) -
                 (*cow_start + *cow_len);
         if (want_clusters < contig_clusters)
             want_clusters = contig_clusters;
 
         /*
          * If the write does not cover the whole extent, we
          * need to calculate how we're going to split the extent.
          * We try to do it on contig_clusters boundaries.
          *
          * Any extent smaller than contig_clusters will be
          * CoWed in its entirety.
          */
         if (leaf_clusters <= contig_clusters)
             *cow_len += leaf_clusters;
         else if (*cow_len || (*cow_start == cpos)) {
             /*
              * This extent needs to be CoW'd from its
              * beginning, so all we have to do is compute
              * how many clusters to grab.  We align
              * want_clusters to the edge of contig_clusters
              * to get better I/O.
              */
             want_clusters = ocfs2_cow_align_length(inode->i_sb,
                                    want_clusters);
 
             if (leaf_clusters < want_clusters)
                 *cow_len += leaf_clusters;
             else
                 *cow_len += want_clusters;
         } else if ((*cow_start + contig_clusters) >=
                (cpos + write_len)) {
             /*
              * Breaking off contig_clusters at the front
              * of the extent will cover our write.  That's
              * easy.
              */
             *cow_len = contig_clusters;
         } else if ((rec_end - cpos) <= contig_clusters) {
             /*
              * Breaking off contig_clusters at the tail of
              * this extent will cover cpos.
              */
             *cow_start = rec_end - contig_clusters;
             *cow_len = contig_clusters;
         } else if ((rec_end - cpos) <= want_clusters) {
             /*
              * While we can't fit the entire write in this
              * extent, we know that the write goes from cpos
              * to the end of the extent.  Break that off.
              * We try to break it at some multiple of
              * contig_clusters from the front of the extent.
              * Failing that (ie, cpos is within
              * contig_clusters of the front), we'll CoW the
              * entire extent.
              */
             *cow_start = ocfs2_cow_align_start(inode->i_sb,
                                *cow_start, cpos);
             *cow_len = rec_end - *cow_start;
         } else {
             /*
              * Ok, the entire write lives in the middle of
              * this extent.  Let's try to slice the extent up
              * nicely.  Optimally, our CoW region starts at
              * m*contig_clusters from the beginning of the
              * extent and goes for n*contig_clusters,
              * covering the entire write.
              */
             *cow_start = ocfs2_cow_align_start(inode->i_sb,
                                *cow_start, cpos);
 
             want_clusters = (cpos + write_len) - *cow_start;
             want_clusters = ocfs2_cow_align_length(inode->i_sb,
                                    want_clusters);
             if (*cow_start + want_clusters <= rec_end)
                 *cow_len = want_clusters;
             else
                 *cow_len = rec_end - *cow_start;
         }
 
         /* Have we covered our entire write yet? */
         if ((*cow_start + *cow_len) >= (cpos + write_len))
             break;
 
         /*
          * If we reach the end of the extent block and don't get enough
          * clusters, continue with the next extent block if possible.
          */
         if (i + 1 == le16_to_cpu(el->l_next_free_rec) &&
             eb && eb->h_next_leaf_blk) {
             brelse(eb_bh);
             eb_bh = NULL;
 
             ret = ocfs2_read_extent_block(INODE_CACHE(inode),
                            le64_to_cpu(eb->h_next_leaf_blk),
                            &eb_bh);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
 
             eb = (struct ocfs2_extent_block *) eb_bh->b_data;
             el = &eb->h_list;
             i = -1;
         }
     }
 
 out:
     brelse(eb_bh);
     return ret;
 }
 
 /*
  * Prepare meta_ac, data_ac and calculate credits when we want to add some
  * num_clusters in data_tree "et" and change the refcount for the old
  * clusters(starting form p_cluster) in the refcount tree.
  *
  * Note:
  * 1. since we may split the old tree, so we at most will need num_clusters + 2
  *    more new leaf records.
  * 2. In some case, we may not need to reserve new clusters(e.g, reflink), so
  *    just give data_ac = NULL.
  */
 static int ocfs2_lock_refcount_allocators(struct super_block *sb,
                     u32 p_cluster, u32 num_clusters,
                     struct ocfs2_extent_tree *et,
                     struct ocfs2_caching_info *ref_ci,
                     struct buffer_head *ref_root_bh,
                     struct ocfs2_alloc_context **meta_ac,
                     struct ocfs2_alloc_context **data_ac,
                     int *credits)
 {
     int ret = 0, meta_add = 0;
     int num_free_extents = ocfs2_num_free_extents(et);
 
     if (num_free_extents < 0) {
         ret = num_free_extents;
         mlog_errno(ret);
         goto out;
     }
 
     if (num_free_extents < num_clusters + 2)
         meta_add =
             ocfs2_extend_meta_needed(et->et_root_el);
 
     *credits += ocfs2_calc_extend_credits(sb, et->et_root_el);
 
     ret = ocfs2_calc_refcount_meta_credits(sb, ref_ci, ref_root_bh,
                            p_cluster, num_clusters,
                            &meta_add, credits);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_lock_refcount_allocators(meta_add, *credits);
     ret = ocfs2_reserve_new_metadata_blocks(OCFS2_SB(sb), meta_add,
                         meta_ac);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     if (data_ac) {
         ret = ocfs2_reserve_clusters(OCFS2_SB(sb), num_clusters,
                          data_ac);
         if (ret)
             mlog_errno(ret);
     }
 
 out:
     if (ret) {
         if (*meta_ac) {
             ocfs2_free_alloc_context(*meta_ac);
             *meta_ac = NULL;
         }
     }
 
     return ret;
 }
 
 static int ocfs2_clear_cow_buffer(handle_t *handle, struct buffer_head *bh)
 {
     BUG_ON(buffer_dirty(bh));
 
     clear_buffer_mapped(bh);
 
     return 0;
 }
 
 int ocfs2_duplicate_clusters_by_page(handle_t *handle,
                      struct inode *inode,
                      u32 cpos, u32 old_cluster,
                      u32 new_cluster, u32 new_len)
 {
     int ret = 0, partial;
     struct super_block *sb = inode->i_sb;
     u64 new_block = ocfs2_clusters_to_blocks(sb, new_cluster);
     struct page *page;
     pgoff_t page_index;
     unsigned int from, to;
     loff_t offset, end, map_end;
     struct address_space *mapping = inode->i_mapping;
 
     trace_ocfs2_duplicate_clusters_by_page(cpos, old_cluster,
                            new_cluster, new_len);
 
     offset = ((loff_t)cpos) << OCFS2_SB(sb)->s_clustersize_bits;
     end = offset + (new_len << OCFS2_SB(sb)->s_clustersize_bits);
     /*
      * We only duplicate pages until we reach the page contains i_size - 1.
      * So trim 'end' to i_size.
      */
     if (end > i_size_read(inode))
         end = i_size_read(inode);
 
     while (offset < end) {
         page_index = offset >> PAGE_SHIFT;
         map_end = ((loff_t)page_index + 1) << PAGE_SHIFT;
         if (map_end > end)
             map_end = end;
 
         /* from, to is the offset within the page. */
         from = offset & (PAGE_SIZE - 1);
         to = PAGE_SIZE;
         if (map_end & (PAGE_SIZE - 1))
             to = map_end & (PAGE_SIZE - 1);
 
 retry:
         page = find_or_create_page(mapping, page_index, GFP_NOFS);
         if (!page) {
             ret = -ENOMEM;
             mlog_errno(ret);
             break;
         }
 
         /*
          * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty
          * page, so write it back.
          */
         if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
             if (PageDirty(page)) {
                 /*
                  * write_on_page will unlock the page on return
                  */
                 ret = write_one_page(page);
                 goto retry;
             }
         }
 
         if (!PageUptodate(page)) {
             struct folio *folio = page_folio(page);
 
             ret = block_read_full_folio(folio, ocfs2_get_block);
             if (ret) {
                 mlog_errno(ret);
                 goto unlock;
             }
             folio_lock(folio);
         }
 
         if (page_has_buffers(page)) {
             ret = walk_page_buffers(handle, page_buffers(page),
                         from, to, &partial,
                         ocfs2_clear_cow_buffer);
             if (ret) {
                 mlog_errno(ret);
                 goto unlock;
             }
         }
 
         ocfs2_map_and_dirty_page(inode,
                      handle, from, to,
                      page, 0, &new_block);
         mark_page_accessed(page);
 unlock:
         unlock_page(page);
         put_page(page);
         page = NULL;
         offset = map_end;
         if (ret)
             break;
     }
 
     return ret;
 }
 
 int ocfs2_duplicate_clusters_by_jbd(handle_t *handle,
                     struct inode *inode,
                     u32 cpos, u32 old_cluster,
                     u32 new_cluster, u32 new_len)
 {
     int ret = 0;
     struct super_block *sb = inode->i_sb;
     struct ocfs2_caching_info *ci = INODE_CACHE(inode);
     int i, blocks = ocfs2_clusters_to_blocks(sb, new_len);
     u64 old_block = ocfs2_clusters_to_blocks(sb, old_cluster);
     u64 new_block = ocfs2_clusters_to_blocks(sb, new_cluster);
     struct ocfs2_super *osb = OCFS2_SB(sb);
     struct buffer_head *old_bh = NULL;
     struct buffer_head *new_bh = NULL;
 
     trace_ocfs2_duplicate_clusters_by_page(cpos, old_cluster,
                            new_cluster, new_len);
 
     for (i = 0; i < blocks; i++, old_block++, new_block++) {
         new_bh = sb_getblk(osb->sb, new_block);
         if (new_bh == NULL) {
             ret = -ENOMEM;
             mlog_errno(ret);
             break;
         }
 
         ocfs2_set_new_buffer_uptodate(ci, new_bh);
 
         ret = ocfs2_read_block(ci, old_block, &old_bh, NULL);
         if (ret) {
             mlog_errno(ret);
             break;
         }
 
         ret = ocfs2_journal_access(handle, ci, new_bh,
                        OCFS2_JOURNAL_ACCESS_CREATE);
         if (ret) {
             mlog_errno(ret);
             break;
         }
 
         memcpy(new_bh->b_data, old_bh->b_data, sb->s_blocksize);
         ocfs2_journal_dirty(handle, new_bh);
 
         brelse(new_bh);
         brelse(old_bh);
         new_bh = NULL;
         old_bh = NULL;
     }
 
     brelse(new_bh);
     brelse(old_bh);
     return ret;
 }
 
 static int ocfs2_clear_ext_refcount(handle_t *handle,
                     struct ocfs2_extent_tree *et,
                     u32 cpos, u32 p_cluster, u32 len,
                     unsigned int ext_flags,
                     struct ocfs2_alloc_context *meta_ac,
                     struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret, index;
     struct ocfs2_extent_rec replace_rec;
     struct ocfs2_path *path = NULL;
     struct ocfs2_extent_list *el;
     struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
     u64 ino = ocfs2_metadata_cache_owner(et->et_ci);
 
     trace_ocfs2_clear_ext_refcount((unsigned long long)ino,
                        cpos, len, p_cluster, ext_flags);
 
     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(sb,
                                    p_cluster));
     replace_rec.e_flags = ext_flags;
     replace_rec.e_flags &= ~OCFS2_EXT_REFCOUNTED;
 
     path = ocfs2_new_path_from_et(et);
     if (!path) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_find_path(et->et_ci, path, cpos);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     el = path_leaf_el(path);
 
     index = ocfs2_search_extent_list(el, cpos);
     if (index == -1) {
         ret = ocfs2_error(sb,
                   "Inode %llu has an extent at cpos %u which can no longer be found\n",
                   (unsigned long long)ino, cpos);
         goto out;
     }
 
     ret = ocfs2_split_extent(handle, et, path, index,
                  &replace_rec, meta_ac, dealloc);
     if (ret)
         mlog_errno(ret);
 
 out:
     ocfs2_free_path(path);
     return ret;
 }
 
 static int ocfs2_replace_clusters(handle_t *handle,
                   struct ocfs2_cow_context *context,
                   u32 cpos, u32 old,
                   u32 new, u32 len,
                   unsigned int ext_flags)
 {
     int ret;
     struct ocfs2_caching_info *ci = context->data_et.et_ci;
     u64 ino = ocfs2_metadata_cache_owner(ci);
 
     trace_ocfs2_replace_clusters((unsigned long long)ino,
                      cpos, old, new, len, ext_flags);
 
     /*If the old clusters is unwritten, no need to duplicate. */
     if (!(ext_flags & OCFS2_EXT_UNWRITTEN)) {
         ret = context->cow_duplicate_clusters(handle, context->inode,
                               cpos, old, new, len);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     ret = ocfs2_clear_ext_refcount(handle, &context->data_et,
                        cpos, new, len, ext_flags,
                        context->meta_ac, &context->dealloc);
     if (ret)
         mlog_errno(ret);
 out:
     return ret;
 }
 
 int ocfs2_cow_sync_writeback(struct super_block *sb,
                  struct inode *inode,
                  u32 cpos, u32 num_clusters)
 {
     int ret;
     loff_t start, end;
 
     if (ocfs2_should_order_data(inode))
         return 0;
 
     start = ((loff_t)cpos) << OCFS2_SB(sb)->s_clustersize_bits;
     end = start + (num_clusters << OCFS2_SB(sb)->s_clustersize_bits) - 1;
 
     ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
     if (ret < 0)
         mlog_errno(ret);
 
     return ret;
 }
 
 static int ocfs2_di_get_clusters(struct ocfs2_cow_context *context,
                  u32 v_cluster, u32 *p_cluster,
                  u32 *num_clusters,
                  unsigned int *extent_flags)
 {
     return ocfs2_get_clusters(context->inode, v_cluster, p_cluster,
                   num_clusters, extent_flags);
 }
 
 static int ocfs2_make_clusters_writable(struct super_block *sb,
                     struct ocfs2_cow_context *context,
                     u32 cpos, u32 p_cluster,
                     u32 num_clusters, unsigned int e_flags)
 {
     int ret, delete, index, credits =  0;
     u32 new_bit, new_len, orig_num_clusters;
     unsigned int set_len;
     struct ocfs2_super *osb = OCFS2_SB(sb);
     handle_t *handle;
     struct buffer_head *ref_leaf_bh = NULL;
     struct ocfs2_caching_info *ref_ci = &context->ref_tree->rf_ci;
     struct ocfs2_refcount_rec rec;
 
     trace_ocfs2_make_clusters_writable(cpos, p_cluster,
                        num_clusters, e_flags);
 
     ret = ocfs2_lock_refcount_allocators(sb, p_cluster, num_clusters,
                          &context->data_et,
                          ref_ci,
                          context->ref_root_bh,
                          &context->meta_ac,
                          &context->data_ac, &credits);
     if (ret) {
         mlog_errno(ret);
         return ret;
     }
 
     if (context->post_refcount)
         credits += context->post_refcount->credits;
 
     credits += context->extra_credits;
     handle = ocfs2_start_trans(osb, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     orig_num_clusters = num_clusters;
 
     while (num_clusters) {
         ret = ocfs2_get_refcount_rec(ref_ci, context->ref_root_bh,
                          p_cluster, num_clusters,
                          &rec, &index, &ref_leaf_bh);
         if (ret) {
             mlog_errno(ret);
             goto out_commit;
         }
 
         BUG_ON(!rec.r_refcount);
         set_len = min((u64)p_cluster + num_clusters,
                   le64_to_cpu(rec.r_cpos) +
                   le32_to_cpu(rec.r_clusters)) - p_cluster;
 
         /*
          * There are many different situation here.
          * 1. If refcount == 1, remove the flag and don't COW.
          * 2. If refcount > 1, allocate clusters.
          *    Here we may not allocate r_len once at a time, so continue
          *    until we reach num_clusters.
          */
         if (le32_to_cpu(rec.r_refcount) == 1) {
             delete = 0;
             ret = ocfs2_clear_ext_refcount(handle,
                                &context->data_et,
                                cpos, p_cluster,
                                set_len, e_flags,
                                context->meta_ac,
                                &context->dealloc);
             if (ret) {
                 mlog_errno(ret);
                 goto out_commit;
             }
         } else {
             delete = 1;
 
             ret = __ocfs2_claim_clusters(handle,
                              context->data_ac,
                              1, set_len,
                              &new_bit, &new_len);
             if (ret) {
                 mlog_errno(ret);
                 goto out_commit;
             }
 
             ret = ocfs2_replace_clusters(handle, context,
                              cpos, p_cluster, new_bit,
                              new_len, e_flags);
             if (ret) {
                 mlog_errno(ret);
                 goto out_commit;
             }
             set_len = new_len;
         }
 
         ret = __ocfs2_decrease_refcount(handle, ref_ci,
                         context->ref_root_bh,
                         p_cluster, set_len,
                         context->meta_ac,
                         &context->dealloc, delete);
         if (ret) {
             mlog_errno(ret);
             goto out_commit;
         }
 
         cpos += set_len;
         p_cluster += set_len;
         num_clusters -= set_len;
         brelse(ref_leaf_bh);
         ref_leaf_bh = NULL;
     }
 
     /* handle any post_cow action. */
     if (context->post_refcount && context->post_refcount->func) {
         ret = context->post_refcount->func(context->inode, handle,
                         context->post_refcount->para);
         if (ret) {
             mlog_errno(ret);
             goto out_commit;
         }
     }
 
     /*
      * Here we should write the new page out first if we are
      * in write-back mode.
      */
     if (context->get_clusters == ocfs2_di_get_clusters) {
         ret = ocfs2_cow_sync_writeback(sb, context->inode, cpos,
                            orig_num_clusters);
         if (ret)
             mlog_errno(ret);
     }
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 
 out:
     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;
     }
     brelse(ref_leaf_bh);
 
     return ret;
 }
 
 static int ocfs2_replace_cow(struct ocfs2_cow_context *context)
 {
     int ret = 0;
     struct inode *inode = context->inode;
     u32 cow_start = context->cow_start, cow_len = context->cow_len;
     u32 p_cluster, num_clusters;
     unsigned int ext_flags;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
     if (!ocfs2_refcount_tree(osb)) {
         return ocfs2_error(inode->i_sb, "Inode %lu want to use refcount tree, but the feature bit is not set in the super block\n",
                    inode->i_ino);
     }
 
     ocfs2_init_dealloc_ctxt(&context->dealloc);
 
     while (cow_len) {
         ret = context->get_clusters(context, cow_start, &p_cluster,
                         &num_clusters, &ext_flags);
         if (ret) {
             mlog_errno(ret);
             break;
         }
 
         BUG_ON(!(ext_flags & OCFS2_EXT_REFCOUNTED));
 
         if (cow_len < num_clusters)
             num_clusters = cow_len;
 
         ret = ocfs2_make_clusters_writable(inode->i_sb, context,
                            cow_start, p_cluster,
                            num_clusters, ext_flags);
         if (ret) {
             mlog_errno(ret);
             break;
         }
 
         cow_len -= num_clusters;
         cow_start += num_clusters;
     }
 
     if (ocfs2_dealloc_has_cluster(&context->dealloc)) {
         ocfs2_schedule_truncate_log_flush(osb, 1);
         ocfs2_run_deallocs(osb, &context->dealloc);
     }
 
     return ret;
 }
 
 /*
  * Starting at cpos, try to CoW write_len clusters.  Don't CoW
  * past max_cpos.  This will stop when it runs into a hole or an
  * unrefcounted extent.
  */
 static int ocfs2_refcount_cow_hunk(struct inode *inode,
                    struct buffer_head *di_bh,
                    u32 cpos, u32 write_len, u32 max_cpos)
 {
     int ret;
     u32 cow_start = 0, cow_len = 0;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_tree *ref_tree;
     struct ocfs2_cow_context *context = NULL;
 
     BUG_ON(!ocfs2_is_refcount_inode(inode));
 
     ret = ocfs2_refcount_cal_cow_clusters(inode, &di->id2.i_list,
                           cpos, write_len, max_cpos,
                           &cow_start, &cow_len);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_refcount_cow_hunk(OCFS2_I(inode)->ip_blkno,
                       cpos, write_len, max_cpos,
                       cow_start, cow_len);
 
     BUG_ON(cow_len == 0);
 
     context = kzalloc(sizeof(struct ocfs2_cow_context), GFP_NOFS);
     if (!context) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_lock_refcount_tree(osb, le64_to_cpu(di->i_refcount_loc),
                        1, &ref_tree, &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     context->inode = inode;
     context->cow_start = cow_start;
     context->cow_len = cow_len;
     context->ref_tree = ref_tree;
     context->ref_root_bh = ref_root_bh;
     context->cow_duplicate_clusters = ocfs2_duplicate_clusters_by_page;
     context->get_clusters = ocfs2_di_get_clusters;
 
     ocfs2_init_dinode_extent_tree(&context->data_et,
                       INODE_CACHE(inode), di_bh);
 
     ret = ocfs2_replace_cow(context);
     if (ret)
         mlog_errno(ret);
 
     /*
      * truncate the extent map here since no matter whether we meet with
      * any error during the action, we shouldn't trust cached extent map
      * any more.
      */
     ocfs2_extent_map_trunc(inode, cow_start);
 
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     brelse(ref_root_bh);
 out:
     kfree(context);
     return ret;
 }
 
 /*
  * CoW any and all clusters between cpos and cpos+write_len.
  * Don't CoW past max_cpos.  If this returns successfully, all
  * clusters between cpos and cpos+write_len are safe to modify.
  */
 int ocfs2_refcount_cow(struct inode *inode,
                struct buffer_head *di_bh,
                u32 cpos, u32 write_len, u32 max_cpos)
 {
     int ret = 0;
     u32 p_cluster, num_clusters;
     unsigned int ext_flags;
 
     while (write_len) {
         ret = ocfs2_get_clusters(inode, cpos, &p_cluster,
                      &num_clusters, &ext_flags);
         if (ret) {
             mlog_errno(ret);
             break;
         }
 
         if (write_len < num_clusters)
             num_clusters = write_len;
 
         if (ext_flags & OCFS2_EXT_REFCOUNTED) {
             ret = ocfs2_refcount_cow_hunk(inode, di_bh, cpos,
                               num_clusters, max_cpos);
             if (ret) {
                 mlog_errno(ret);
                 break;
             }
         }
 
         write_len -= num_clusters;
         cpos += num_clusters;
     }
 
     return ret;
 }
 
 static int ocfs2_xattr_value_get_clusters(struct ocfs2_cow_context *context,
                       u32 v_cluster, u32 *p_cluster,
                       u32 *num_clusters,
                       unsigned int *extent_flags)
 {
     struct inode *inode = context->inode;
     struct ocfs2_xattr_value_root *xv = context->cow_object;
 
     return ocfs2_xattr_get_clusters(inode, v_cluster, p_cluster,
                     num_clusters, &xv->xr_list,
                     extent_flags);
 }
 
 /*
  * Given a xattr value root, calculate the most meta/credits we need for
  * refcount tree change if we truncate it to 0.
  */
 int ocfs2_refcounted_xattr_delete_need(struct inode *inode,
                        struct ocfs2_caching_info *ref_ci,
                        struct buffer_head *ref_root_bh,
                        struct ocfs2_xattr_value_root *xv,
                        int *meta_add, int *credits)
 {
     int ret = 0, index, ref_blocks = 0;
     u32 p_cluster, num_clusters;
     u32 cpos = 0, clusters = le32_to_cpu(xv->xr_clusters);
     struct ocfs2_refcount_block *rb;
     struct ocfs2_refcount_rec rec;
     struct buffer_head *ref_leaf_bh = NULL;
 
     while (cpos < clusters) {
         ret = ocfs2_xattr_get_clusters(inode, cpos, &p_cluster,
                            &num_clusters, &xv->xr_list,
                            NULL);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         cpos += num_clusters;
 
         while (num_clusters) {
             ret = ocfs2_get_refcount_rec(ref_ci, ref_root_bh,
                              p_cluster, num_clusters,
                              &rec, &index,
                              &ref_leaf_bh);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
 
             BUG_ON(!rec.r_refcount);
 
             rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
 
             /*
              * We really don't know whether the other clusters is in
              * this refcount block or not, so just take the worst
              * case that all the clusters are in this block and each
              * one will split a refcount rec, so totally we need
              * clusters * 2 new refcount rec.
              */
             if (le16_to_cpu(rb->rf_records.rl_used) + clusters * 2 >
                 le16_to_cpu(rb->rf_records.rl_count))
                 ref_blocks++;
 
             *credits += 1;
             brelse(ref_leaf_bh);
             ref_leaf_bh = NULL;
 
             if (num_clusters <= le32_to_cpu(rec.r_clusters))
                 break;
             else
                 num_clusters -= le32_to_cpu(rec.r_clusters);
             p_cluster += num_clusters;
         }
     }
 
     *meta_add += ref_blocks;
     if (!ref_blocks)
         goto out;
 
     rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
     if (le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL)
         *credits += OCFS2_EXPAND_REFCOUNT_TREE_CREDITS;
     else {
         struct ocfs2_extent_tree et;
 
         ocfs2_init_refcount_extent_tree(&et, ref_ci, ref_root_bh);
         *credits += ocfs2_calc_extend_credits(inode->i_sb,
                               et.et_root_el);
     }
 
 out:
     brelse(ref_leaf_bh);
     return ret;
 }
 
 /*
  * Do CoW for xattr.
  */
 int ocfs2_refcount_cow_xattr(struct inode *inode,
                  struct ocfs2_dinode *di,
                  struct ocfs2_xattr_value_buf *vb,
                  struct ocfs2_refcount_tree *ref_tree,
                  struct buffer_head *ref_root_bh,
                  u32 cpos, u32 write_len,
                  struct ocfs2_post_refcount *post)
 {
     int ret;
     struct ocfs2_xattr_value_root *xv = vb->vb_xv;
     struct ocfs2_cow_context *context = NULL;
     u32 cow_start, cow_len;
 
     BUG_ON(!ocfs2_is_refcount_inode(inode));
 
     ret = ocfs2_refcount_cal_cow_clusters(inode, &xv->xr_list,
                           cpos, write_len, UINT_MAX,
                           &cow_start, &cow_len);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     BUG_ON(cow_len == 0);
 
     context = kzalloc(sizeof(struct ocfs2_cow_context), GFP_NOFS);
     if (!context) {
         ret = -ENOMEM;
         mlog_errno(ret);
         goto out;
     }
 
     context->inode = inode;
     context->cow_start = cow_start;
     context->cow_len = cow_len;
     context->ref_tree = ref_tree;
     context->ref_root_bh = ref_root_bh;
     context->cow_object = xv;
 
     context->cow_duplicate_clusters = ocfs2_duplicate_clusters_by_jbd;
     /* We need the extra credits for duplicate_clusters by jbd. */
     context->extra_credits =
         ocfs2_clusters_to_blocks(inode->i_sb, 1) * cow_len;
     context->get_clusters = ocfs2_xattr_value_get_clusters;
     context->post_refcount = post;
 
     ocfs2_init_xattr_value_extent_tree(&context->data_et,
                        INODE_CACHE(inode), vb);
 
     ret = ocfs2_replace_cow(context);
     if (ret)
         mlog_errno(ret);
 
 out:
     kfree(context);
     return ret;
 }
 
 /*
  * Insert a new extent into refcount tree and mark a extent rec
  * as refcounted in the dinode tree.
  */
 int ocfs2_add_refcount_flag(struct inode *inode,
                 struct ocfs2_extent_tree *data_et,
                 struct ocfs2_caching_info *ref_ci,
                 struct buffer_head *ref_root_bh,
                 u32 cpos, u32 p_cluster, u32 num_clusters,
                 struct ocfs2_cached_dealloc_ctxt *dealloc,
                 struct ocfs2_post_refcount *post)
 {
     int ret;
     handle_t *handle;
     int credits = 1, ref_blocks = 0;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct ocfs2_alloc_context *meta_ac = NULL;
 
     /* We need to be able to handle at least an extent tree split. */
     ref_blocks = ocfs2_extend_meta_needed(data_et->et_root_el);
 
     ret = ocfs2_calc_refcount_meta_credits(inode->i_sb,
                            ref_ci, ref_root_bh,
                            p_cluster, num_clusters,
                            &ref_blocks, &credits);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     trace_ocfs2_add_refcount_flag(ref_blocks, credits);
 
     if (ref_blocks) {
         ret = ocfs2_reserve_new_metadata_blocks(osb,
                             ref_blocks, &meta_ac);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     if (post)
         credits += post->credits;
 
     handle = ocfs2_start_trans(osb, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_mark_extent_refcounted(inode, data_et, handle,
                        cpos, num_clusters, p_cluster,
                        meta_ac, dealloc);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = __ocfs2_increase_refcount(handle, ref_ci, ref_root_bh,
                     p_cluster, num_clusters, 0,
                     meta_ac, dealloc);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     if (post && post->func) {
         ret = post->func(inode, handle, post->para);
         if (ret)
             mlog_errno(ret);
     }
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 out:
     if (meta_ac)
         ocfs2_free_alloc_context(meta_ac);
     return ret;
 }
 
 static int ocfs2_change_ctime(struct inode *inode,
                   struct buffer_head *di_bh)
 {
     int ret;
     handle_t *handle;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
 
     handle = ocfs2_start_trans(OCFS2_SB(inode->i_sb),
                    OCFS2_INODE_UPDATE_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     inode->i_ctime = current_time(inode);
     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(OCFS2_SB(inode->i_sb), handle);
 out:
     return ret;
 }
 
 static int ocfs2_attach_refcount_tree(struct inode *inode,
                       struct buffer_head *di_bh)
 {
     int ret, data_changed = 0;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_inode_info *oi = OCFS2_I(inode);
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct ocfs2_refcount_tree *ref_tree;
     unsigned int ext_flags;
     loff_t size;
     u32 cpos, num_clusters, clusters, p_cluster;
     struct ocfs2_cached_dealloc_ctxt dealloc;
     struct ocfs2_extent_tree di_et;
 
     ocfs2_init_dealloc_ctxt(&dealloc);
 
     if (!ocfs2_is_refcount_inode(inode)) {
         ret = ocfs2_create_refcount_tree(inode, di_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     BUG_ON(!di->i_refcount_loc);
     ret = ocfs2_lock_refcount_tree(osb,
                        le64_to_cpu(di->i_refcount_loc), 1,
                        &ref_tree, &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
         goto attach_xattr;
 
     ocfs2_init_dinode_extent_tree(&di_et, INODE_CACHE(inode), di_bh);
 
     size = i_size_read(inode);
     clusters = ocfs2_clusters_for_bytes(inode->i_sb, size);
 
     cpos = 0;
     while (cpos < clusters) {
         ret = ocfs2_get_clusters(inode, cpos, &p_cluster,
                      &num_clusters, &ext_flags);
         if (ret) {
             mlog_errno(ret);
             goto unlock;
         }
         if (p_cluster && !(ext_flags & OCFS2_EXT_REFCOUNTED)) {
             ret = ocfs2_add_refcount_flag(inode, &di_et,
                               &ref_tree->rf_ci,
                               ref_root_bh, cpos,
                               p_cluster, num_clusters,
                               &dealloc, NULL);
             if (ret) {
                 mlog_errno(ret);
                 goto unlock;
             }
 
             data_changed = 1;
         }
         cpos += num_clusters;
     }
 
 attach_xattr:
     if (oi->ip_dyn_features & OCFS2_HAS_XATTR_FL) {
         ret = ocfs2_xattr_attach_refcount_tree(inode, di_bh,
                                &ref_tree->rf_ci,
                                ref_root_bh,
                                &dealloc);
         if (ret) {
             mlog_errno(ret);
             goto unlock;
         }
     }
 
     if (data_changed) {
         ret = ocfs2_change_ctime(inode, di_bh);
         if (ret)
             mlog_errno(ret);
     }
 
 unlock:
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     brelse(ref_root_bh);
 
     if (!ret && ocfs2_dealloc_has_cluster(&dealloc)) {
         ocfs2_schedule_truncate_log_flush(osb, 1);
         ocfs2_run_deallocs(osb, &dealloc);
     }
 out:
     /*
      * Empty the extent map so that we may get the right extent
      * record from the disk.
      */
     ocfs2_extent_map_trunc(inode, 0);
 
     return ret;
 }
 
 static int ocfs2_add_refcounted_extent(struct inode *inode,
                    struct ocfs2_extent_tree *et,
                    struct ocfs2_caching_info *ref_ci,
                    struct buffer_head *ref_root_bh,
                    u32 cpos, u32 p_cluster, u32 num_clusters,
                    unsigned int ext_flags,
                    struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret;
     handle_t *handle;
     int credits = 0;
     struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
     struct ocfs2_alloc_context *meta_ac = NULL;
 
     ret = ocfs2_lock_refcount_allocators(inode->i_sb,
                          p_cluster, num_clusters,
                          et, ref_ci,
                          ref_root_bh, &meta_ac,
                          NULL, &credits);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     handle = ocfs2_start_trans(osb, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_insert_extent(handle, et, cpos,
             ocfs2_clusters_to_blocks(inode->i_sb, p_cluster),
             num_clusters, ext_flags, meta_ac);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = ocfs2_increase_refcount(handle, ref_ci, ref_root_bh,
                       p_cluster, num_clusters,
                       meta_ac, dealloc);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     ret = dquot_alloc_space_nodirty(inode,
         ocfs2_clusters_to_bytes(osb->sb, num_clusters));
     if (ret)
         mlog_errno(ret);
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 out:
     if (meta_ac)
         ocfs2_free_alloc_context(meta_ac);
     return ret;
 }
 
 static int ocfs2_duplicate_inline_data(struct inode *s_inode,
                        struct buffer_head *s_bh,
                        struct inode *t_inode,
                        struct buffer_head *t_bh)
 {
     int ret;
     handle_t *handle;
     struct ocfs2_super *osb = OCFS2_SB(s_inode->i_sb);
     struct ocfs2_dinode *s_di = (struct ocfs2_dinode *)s_bh->b_data;
     struct ocfs2_dinode *t_di = (struct ocfs2_dinode *)t_bh->b_data;
 
     BUG_ON(!(OCFS2_I(s_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL));
 
     handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(t_inode), t_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     t_di->id2.i_data.id_count = s_di->id2.i_data.id_count;
     memcpy(t_di->id2.i_data.id_data, s_di->id2.i_data.id_data,
            le16_to_cpu(s_di->id2.i_data.id_count));
     spin_lock(&OCFS2_I(t_inode)->ip_lock);
     OCFS2_I(t_inode)->ip_dyn_features |= OCFS2_INLINE_DATA_FL;
     t_di->i_dyn_features = cpu_to_le16(OCFS2_I(t_inode)->ip_dyn_features);
     spin_unlock(&OCFS2_I(t_inode)->ip_lock);
 
     ocfs2_journal_dirty(handle, t_bh);
 
 out_commit:
     ocfs2_commit_trans(osb, handle);
 out:
     return ret;
 }
 
 static int ocfs2_duplicate_extent_list(struct inode *s_inode,
                 struct inode *t_inode,
                 struct buffer_head *t_bh,
                 struct ocfs2_caching_info *ref_ci,
                 struct buffer_head *ref_root_bh,
                 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     int ret = 0;
     u32 p_cluster, num_clusters, clusters, cpos;
     loff_t size;
     unsigned int ext_flags;
     struct ocfs2_extent_tree et;
 
     ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(t_inode), t_bh);
 
     size = i_size_read(s_inode);
     clusters = ocfs2_clusters_for_bytes(s_inode->i_sb, size);
 
     cpos = 0;
     while (cpos < clusters) {
         ret = ocfs2_get_clusters(s_inode, cpos, &p_cluster,
                      &num_clusters, &ext_flags);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
         if (p_cluster) {
             ret = ocfs2_add_refcounted_extent(t_inode, &et,
                               ref_ci, ref_root_bh,
                               cpos, p_cluster,
                               num_clusters,
                               ext_flags,
                               dealloc);
             if (ret) {
                 mlog_errno(ret);
                 goto out;
             }
         }
 
         cpos += num_clusters;
     }
 
 out:
     return ret;
 }
 
 /*
  * change the new file's attributes to the src.
  *
  * reflink creates a snapshot of a file, that means the attributes
  * must be identical except for three exceptions - nlink, ino, and ctime.
  */
 static int ocfs2_complete_reflink(struct inode *s_inode,
                   struct buffer_head *s_bh,
                   struct inode *t_inode,
                   struct buffer_head *t_bh,
                   bool preserve)
 {
     int ret;
     handle_t *handle;
     struct ocfs2_dinode *s_di = (struct ocfs2_dinode *)s_bh->b_data;
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)t_bh->b_data;
     loff_t size = i_size_read(s_inode);
 
     handle = ocfs2_start_trans(OCFS2_SB(t_inode->i_sb),
                    OCFS2_INODE_UPDATE_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         return ret;
     }
 
     ret = ocfs2_journal_access_di(handle, INODE_CACHE(t_inode), t_bh,
                       OCFS2_JOURNAL_ACCESS_WRITE);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
     spin_lock(&OCFS2_I(t_inode)->ip_lock);
     OCFS2_I(t_inode)->ip_clusters = OCFS2_I(s_inode)->ip_clusters;
     OCFS2_I(t_inode)->ip_attr = OCFS2_I(s_inode)->ip_attr;
     OCFS2_I(t_inode)->ip_dyn_features = OCFS2_I(s_inode)->ip_dyn_features;
     spin_unlock(&OCFS2_I(t_inode)->ip_lock);
     i_size_write(t_inode, size);
     t_inode->i_blocks = s_inode->i_blocks;
 
     di->i_xattr_inline_size = s_di->i_xattr_inline_size;
     di->i_clusters = s_di->i_clusters;
     di->i_size = s_di->i_size;
     di->i_dyn_features = s_di->i_dyn_features;
     di->i_attr = s_di->i_attr;
 
     if (preserve) {
         t_inode->i_uid = s_inode->i_uid;
         t_inode->i_gid = s_inode->i_gid;
         t_inode->i_mode = s_inode->i_mode;
         di->i_uid = s_di->i_uid;
         di->i_gid = s_di->i_gid;
         di->i_mode = s_di->i_mode;
 
         /*
          * update time.
          * we want mtime to appear identical to the source and
          * update ctime.
          */
         t_inode->i_ctime = current_time(t_inode);
 
         di->i_ctime = cpu_to_le64(t_inode->i_ctime.tv_sec);
         di->i_ctime_nsec = cpu_to_le32(t_inode->i_ctime.tv_nsec);
 
         t_inode->i_mtime = s_inode->i_mtime;
         di->i_mtime = s_di->i_mtime;
         di->i_mtime_nsec = s_di->i_mtime_nsec;
     }
 
     ocfs2_journal_dirty(handle, t_bh);
 
 out_commit:
     ocfs2_commit_trans(OCFS2_SB(t_inode->i_sb), handle);
     return ret;
 }
 
 static int ocfs2_create_reflink_node(struct inode *s_inode,
                      struct buffer_head *s_bh,
                      struct inode *t_inode,
                      struct buffer_head *t_bh,
                      bool preserve)
 {
     int ret;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_cached_dealloc_ctxt dealloc;
     struct ocfs2_super *osb = OCFS2_SB(s_inode->i_sb);
     struct ocfs2_dinode *di = (struct ocfs2_dinode *)s_bh->b_data;
     struct ocfs2_refcount_tree *ref_tree;
 
     ocfs2_init_dealloc_ctxt(&dealloc);
 
     ret = ocfs2_set_refcount_tree(t_inode, t_bh,
                       le64_to_cpu(di->i_refcount_loc));
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     if (OCFS2_I(s_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
         ret = ocfs2_duplicate_inline_data(s_inode, s_bh,
                           t_inode, t_bh);
         if (ret)
             mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_lock_refcount_tree(osb, le64_to_cpu(di->i_refcount_loc),
                        1, &ref_tree, &ref_root_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_duplicate_extent_list(s_inode, t_inode, t_bh,
                       &ref_tree->rf_ci, ref_root_bh,
                       &dealloc);
     if (ret) {
         mlog_errno(ret);
         goto out_unlock_refcount;
     }
 
 out_unlock_refcount:
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     brelse(ref_root_bh);
 out:
     if (ocfs2_dealloc_has_cluster(&dealloc)) {
         ocfs2_schedule_truncate_log_flush(osb, 1);
         ocfs2_run_deallocs(osb, &dealloc);
     }
 
     return ret;
 }
 
 static int __ocfs2_reflink(struct dentry *old_dentry,
                struct buffer_head *old_bh,
                struct inode *new_inode,
                bool preserve)
 {
     int ret;
     struct inode *inode = d_inode(old_dentry);
     struct buffer_head *new_bh = NULL;
 
     if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE) {
         ret = -EINVAL;
         mlog_errno(ret);
         goto out;
     }
 
     ret = filemap_fdatawrite(inode->i_mapping);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     ret = ocfs2_attach_refcount_tree(inode, old_bh);
     if (ret) {
         mlog_errno(ret);
         goto out;
     }
 
     inode_lock_nested(new_inode, I_MUTEX_CHILD);
     ret = ocfs2_inode_lock_nested(new_inode, &new_bh, 1,
                       OI_LS_REFLINK_TARGET);
     if (ret) {
         mlog_errno(ret);
         goto out_unlock;
     }
 
     ret = ocfs2_create_reflink_node(inode, old_bh,
                     new_inode, new_bh, preserve);
     if (ret) {
         mlog_errno(ret);
         goto inode_unlock;
     }
 
     if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_XATTR_FL) {
         ret = ocfs2_reflink_xattrs(inode, old_bh,
                        new_inode, new_bh,
                        preserve);
         if (ret) {
             mlog_errno(ret);
             goto inode_unlock;
         }
     }
 
     ret = ocfs2_complete_reflink(inode, old_bh,
                      new_inode, new_bh, preserve);
     if (ret)
         mlog_errno(ret);
 
 inode_unlock:
     ocfs2_inode_unlock(new_inode, 1);
     brelse(new_bh);
 out_unlock:
     inode_unlock(new_inode);
 out:
     if (!ret) {
         ret = filemap_fdatawait(inode->i_mapping);
         if (ret)
             mlog_errno(ret);
     }
     return ret;
 }
 
 static int ocfs2_reflink(struct dentry *old_dentry, struct inode *dir,
              struct dentry *new_dentry, bool preserve)
 {
     int error, had_lock;
     struct inode *inode = d_inode(old_dentry);
     struct buffer_head *old_bh = NULL;
     struct inode *new_orphan_inode = NULL;
     struct ocfs2_lock_holder oh;
 
     if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)))
         return -EOPNOTSUPP;
 
 
     error = ocfs2_create_inode_in_orphan(dir, inode->i_mode,
                          &new_orphan_inode);
     if (error) {
         mlog_errno(error);
         goto out;
     }
 
     error = ocfs2_rw_lock(inode, 1);
     if (error) {
         mlog_errno(error);
         goto out;
     }
 
     error = ocfs2_inode_lock(inode, &old_bh, 1);
     if (error) {
         mlog_errno(error);
         ocfs2_rw_unlock(inode, 1);
         goto out;
     }
 
     down_write(&OCFS2_I(inode)->ip_xattr_sem);
     down_write(&OCFS2_I(inode)->ip_alloc_sem);
     error = __ocfs2_reflink(old_dentry, old_bh,
                 new_orphan_inode, preserve);
     up_write(&OCFS2_I(inode)->ip_alloc_sem);
     up_write(&OCFS2_I(inode)->ip_xattr_sem);
 
     ocfs2_inode_unlock(inode, 1);
     ocfs2_rw_unlock(inode, 1);
     brelse(old_bh);
 
     if (error) {
         mlog_errno(error);
         goto out;
     }
 
     had_lock = ocfs2_inode_lock_tracker(new_orphan_inode, NULL, 1,
                         &oh);
     if (had_lock < 0) {
         error = had_lock;
         mlog_errno(error);
         goto out;
     }
 
     /* If the security isn't preserved, we need to re-initialize them. */
     if (!preserve) {
         error = ocfs2_init_security_and_acl(dir, new_orphan_inode,
                             &new_dentry->d_name);
         if (error)
             mlog_errno(error);
     }
     if (!error) {
         error = ocfs2_mv_orphaned_inode_to_new(dir, new_orphan_inode,
                                new_dentry);
         if (error)
             mlog_errno(error);
     }
     ocfs2_inode_unlock_tracker(new_orphan_inode, 1, &oh, had_lock);
 
 out:
     if (new_orphan_inode) {
         /*
          * We need to open_unlock the inode no matter whether we
          * succeed or not, so that other nodes can delete it later.
          */
         ocfs2_open_unlock(new_orphan_inode);
         if (error)
             iput(new_orphan_inode);
     }
 
     return error;
 }
 
 /*
  * Below here are the bits used by OCFS2_IOC_REFLINK() to fake
  * sys_reflink().  This will go away when vfs_reflink() exists in
  * fs/namei.c.
  */
 
 /* copied from may_create in VFS. */
 static inline int ocfs2_may_create(struct inode *dir, struct dentry *child)
 {
     if (d_really_is_positive(child))
         return -EEXIST;
     if (IS_DEADDIR(dir))
         return -ENOENT;
     return inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC);
 }
 
 /**
  * ocfs2_vfs_reflink - Create a reference-counted link
  *
  * @old_dentry:        source dentry + inode
  * @dir:       directory to create the target
  * @new_dentry:        target dentry
  * @preserve:  if true, preserve all file attributes
  */
 static int ocfs2_vfs_reflink(struct dentry *old_dentry, struct inode *dir,
                  struct dentry *new_dentry, bool preserve)
 {
     struct inode *inode = d_inode(old_dentry);
     int error;
 
     if (!inode)
         return -ENOENT;
 
     error = ocfs2_may_create(dir, new_dentry);
     if (error)
         return error;
 
     if (dir->i_sb != inode->i_sb)
         return -EXDEV;
 
     /*
      * A reflink to an append-only or immutable file cannot be created.
      */
     if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
         return -EPERM;
 
     /* Only regular files can be reflinked. */
     if (!S_ISREG(inode->i_mode))
         return -EPERM;
 
     /*
      * If the caller wants to preserve ownership, they require the
      * rights to do so.
      */
     if (preserve) {
         if (!uid_eq(current_fsuid(), inode->i_uid) && !capable(CAP_CHOWN))
             return -EPERM;
         if (!in_group_p(inode->i_gid) && !capable(CAP_CHOWN))
             return -EPERM;
     }
 
     /*
      * If the caller is modifying any aspect of the attributes, they
      * are not creating a snapshot.  They need read permission on the
      * file.
      */
     if (!preserve) {
         error = inode_permission(&init_user_ns, inode, MAY_READ);
         if (error)
             return error;
     }
 
     inode_lock(inode);
     error = dquot_initialize(dir);
     if (!error)
         error = ocfs2_reflink(old_dentry, dir, new_dentry, preserve);
     inode_unlock(inode);
     if (!error)
         fsnotify_create(dir, new_dentry);
     return error;
 }
 /*
  * Most codes are copied from sys_linkat.
  */
 int ocfs2_reflink_ioctl(struct inode *inode,
             const char __user *oldname,
             const char __user *newname,
             bool preserve)
 {
     struct dentry *new_dentry;
     struct path old_path, new_path;
     int error;
 
     if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)))
         return -EOPNOTSUPP;
 
     error = user_path_at(AT_FDCWD, oldname, 0, &old_path);
     if (error) {
         mlog_errno(error);
         return error;
     }
 
     new_dentry = user_path_create(AT_FDCWD, newname, &new_path, 0);
     error = PTR_ERR(new_dentry);
     if (IS_ERR(new_dentry)) {
         mlog_errno(error);
         goto out;
     }
 
     error = -EXDEV;
     if (old_path.mnt != new_path.mnt) {
         mlog_errno(error);
         goto out_dput;
     }
 
     error = ocfs2_vfs_reflink(old_path.dentry,
                   d_inode(new_path.dentry),
                   new_dentry, preserve);
 out_dput:
     done_path_create(&new_path, new_dentry);
 out:
     path_put(&old_path);
 
     return error;
 }
 
 /* Update destination inode size, if necessary. */
 int ocfs2_reflink_update_dest(struct inode *dest,
                   struct buffer_head *d_bh,
                   loff_t newlen)
 {
     handle_t *handle;
     int ret;
 
     dest->i_blocks = ocfs2_inode_sector_count(dest);
 
     if (newlen <= i_size_read(dest))
         return 0;
 
     handle = ocfs2_start_trans(OCFS2_SB(dest->i_sb),
                    OCFS2_INODE_UPDATE_CREDITS);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         mlog_errno(ret);
         return ret;
     }
 
     /* Extend i_size if needed. */
     spin_lock(&OCFS2_I(dest)->ip_lock);
     if (newlen > i_size_read(dest))
         i_size_write(dest, newlen);
     spin_unlock(&OCFS2_I(dest)->ip_lock);
     dest->i_ctime = dest->i_mtime = current_time(dest);
 
     ret = ocfs2_mark_inode_dirty(handle, dest, d_bh);
     if (ret) {
         mlog_errno(ret);
         goto out_commit;
     }
 
 out_commit:
     ocfs2_commit_trans(OCFS2_SB(dest->i_sb), handle);
     return ret;
 }
 
 /* Remap the range pos_in:len in s_inode to pos_out:len in t_inode. */
 static loff_t ocfs2_reflink_remap_extent(struct inode *s_inode,
                      struct buffer_head *s_bh,
                      loff_t pos_in,
                      struct inode *t_inode,
                      struct buffer_head *t_bh,
                      loff_t pos_out,
                      loff_t len,
                      struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
     struct ocfs2_extent_tree s_et;
     struct ocfs2_extent_tree t_et;
     struct ocfs2_dinode *dis;
     struct buffer_head *ref_root_bh = NULL;
     struct ocfs2_refcount_tree *ref_tree;
     struct ocfs2_super *osb;
     loff_t remapped_bytes = 0;
     loff_t pstart, plen;
     u32 p_cluster, num_clusters, slast, spos, tpos, remapped_clus = 0;
     unsigned int ext_flags;
     int ret = 0;
 
     osb = OCFS2_SB(s_inode->i_sb);
     dis = (struct ocfs2_dinode *)s_bh->b_data;
     ocfs2_init_dinode_extent_tree(&s_et, INODE_CACHE(s_inode), s_bh);
     ocfs2_init_dinode_extent_tree(&t_et, INODE_CACHE(t_inode), t_bh);
 
     spos = ocfs2_bytes_to_clusters(s_inode->i_sb, pos_in);
     tpos = ocfs2_bytes_to_clusters(t_inode->i_sb, pos_out);
     slast = ocfs2_clusters_for_bytes(s_inode->i_sb, pos_in + len);
 
     while (spos < slast) {
         if (fatal_signal_pending(current)) {
             ret = -EINTR;
             goto out;
         }
 
         /* Look up the extent. */
         ret = ocfs2_get_clusters(s_inode, spos, &p_cluster,
                      &num_clusters, &ext_flags);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         num_clusters = min_t(u32, num_clusters, slast - spos);
 
         /* Punch out the dest range. */
         pstart = ocfs2_clusters_to_bytes(t_inode->i_sb, tpos);
         plen = ocfs2_clusters_to_bytes(t_inode->i_sb, num_clusters);
         ret = ocfs2_remove_inode_range(t_inode, t_bh, pstart, plen);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         if (p_cluster == 0)
             goto next_loop;
 
         /* Lock the refcount btree... */
         ret = ocfs2_lock_refcount_tree(osb,
                            le64_to_cpu(dis->i_refcount_loc),
                            1, &ref_tree, &ref_root_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
 
         /* Mark s_inode's extent as refcounted. */
         if (!(ext_flags & OCFS2_EXT_REFCOUNTED)) {
             ret = ocfs2_add_refcount_flag(s_inode, &s_et,
                               &ref_tree->rf_ci,
                               ref_root_bh, spos,
                               p_cluster, num_clusters,
                               dealloc, NULL);
             if (ret) {
                 mlog_errno(ret);
                 goto out_unlock_refcount;
             }
         }
 
         /* Map in the new extent. */
         ext_flags |= OCFS2_EXT_REFCOUNTED;
         ret = ocfs2_add_refcounted_extent(t_inode, &t_et,
                           &ref_tree->rf_ci,
                           ref_root_bh,
                           tpos, p_cluster,
                           num_clusters,
                           ext_flags,
                           dealloc);
         if (ret) {
             mlog_errno(ret);
             goto out_unlock_refcount;
         }
 
         ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
         brelse(ref_root_bh);
 next_loop:
         spos += num_clusters;
         tpos += num_clusters;
         remapped_clus += num_clusters;
     }
 
     goto out;
 out_unlock_refcount:
     ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
     brelse(ref_root_bh);
 out:
     remapped_bytes = ocfs2_clusters_to_bytes(t_inode->i_sb, remapped_clus);
     remapped_bytes = min_t(loff_t, len, remapped_bytes);
 
     return remapped_bytes > 0 ? remapped_bytes : ret;
 }
 
 /* Set up refcount tree and remap s_inode to t_inode. */
 loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
                   struct buffer_head *s_bh,
                   loff_t pos_in,
                   struct inode *t_inode,
                   struct buffer_head *t_bh,
                   loff_t pos_out,
                   loff_t len)
 {
     struct ocfs2_cached_dealloc_ctxt dealloc;
     struct ocfs2_super *osb;
     struct ocfs2_dinode *dis;
     struct ocfs2_dinode *dit;
     loff_t ret;
 
     osb = OCFS2_SB(s_inode->i_sb);
     dis = (struct ocfs2_dinode *)s_bh->b_data;
     dit = (struct ocfs2_dinode *)t_bh->b_data;
     ocfs2_init_dealloc_ctxt(&dealloc);
 
     /*
      * If we're reflinking the entire file and the source is inline
      * data, just copy the contents.
      */
     if (pos_in == pos_out && pos_in == 0 && len == i_size_read(s_inode) &&
         i_size_read(t_inode) <= len &&
         (OCFS2_I(s_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)) {
         ret = ocfs2_duplicate_inline_data(s_inode, s_bh, t_inode, t_bh);
         if (ret)
             mlog_errno(ret);
         goto out;
     }
 
     /*
      * If both inodes belong to two different refcount groups then
      * forget it because we don't know how (or want) to go merging
      * refcount trees.
      */
     ret = -EOPNOTSUPP;
     if (ocfs2_is_refcount_inode(s_inode) &&
         ocfs2_is_refcount_inode(t_inode) &&
         le64_to_cpu(dis->i_refcount_loc) !=
         le64_to_cpu(dit->i_refcount_loc))
         goto out;
 
     /* Neither inode has a refcount tree.  Add one to s_inode. */
     if (!ocfs2_is_refcount_inode(s_inode) &&
         !ocfs2_is_refcount_inode(t_inode)) {
         ret = ocfs2_create_refcount_tree(s_inode, s_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     /* Ensure that both inodes end up with the same refcount tree. */
     if (!ocfs2_is_refcount_inode(s_inode)) {
         ret = ocfs2_set_refcount_tree(s_inode, s_bh,
                           le64_to_cpu(dit->i_refcount_loc));
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
     if (!ocfs2_is_refcount_inode(t_inode)) {
         ret = ocfs2_set_refcount_tree(t_inode, t_bh,
                           le64_to_cpu(dis->i_refcount_loc));
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     /* Turn off inline data in the dest file. */
     if (OCFS2_I(t_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
         ret = ocfs2_convert_inline_data_to_extents(t_inode, t_bh);
         if (ret) {
             mlog_errno(ret);
             goto out;
         }
     }
 
     /* Actually remap extents now. */
     ret = ocfs2_reflink_remap_extent(s_inode, s_bh, pos_in, t_inode, t_bh,
                      pos_out, len, &dealloc);
     if (ret < 0) {
         mlog_errno(ret);
         goto out;
     }
 
 out:
     if (ocfs2_dealloc_has_cluster(&dealloc)) {
         ocfs2_schedule_truncate_log_flush(osb, 1);
         ocfs2_run_deallocs(osb, &dealloc);
     }
 
     return ret;
 }
 
 /* Lock an inode and grab a bh pointing to the inode. */
 int ocfs2_reflink_inodes_lock(struct inode *s_inode,
                   struct buffer_head **bh_s,
                   struct inode *t_inode,
                   struct buffer_head **bh_t)
 {
     struct inode *inode1 = s_inode;
     struct inode *inode2 = t_inode;
     struct ocfs2_inode_info *oi1;
     struct ocfs2_inode_info *oi2;
     struct buffer_head *bh1 = NULL;
     struct buffer_head *bh2 = NULL;
     bool same_inode = (s_inode == t_inode);
     bool need_swap = (inode1->i_ino > inode2->i_ino);
     int status;
 
     /* First grab the VFS and rw locks. */
     lock_two_nondirectories(s_inode, t_inode);
     if (need_swap)
         swap(inode1, inode2);
 
     status = ocfs2_rw_lock(inode1, 1);
     if (status) {
         mlog_errno(status);
         goto out_i1;
     }
     if (!same_inode) {
         status = ocfs2_rw_lock(inode2, 1);
         if (status) {
             mlog_errno(status);
             goto out_i2;
         }
     }
 
     /* Now go for the cluster locks */
     oi1 = OCFS2_I(inode1);
     oi2 = OCFS2_I(inode2);
 
     trace_ocfs2_double_lock((unsigned long long)oi1->ip_blkno,
                 (unsigned long long)oi2->ip_blkno);
 
     /* We always want to lock the one with the lower lockid first. */
     if (oi1->ip_blkno > oi2->ip_blkno)
         mlog_errno(-ENOLCK);
 
     /* lock id1 */
     status = ocfs2_inode_lock_nested(inode1, &bh1, 1,
                      OI_LS_REFLINK_TARGET);
     if (status < 0) {
         if (status != -ENOENT)
             mlog_errno(status);
         goto out_rw2;
     }
 
     /* lock id2 */
     if (!same_inode) {
         status = ocfs2_inode_lock_nested(inode2, &bh2, 1,
                          OI_LS_REFLINK_TARGET);
         if (status < 0) {
             if (status != -ENOENT)
                 mlog_errno(status);
             goto out_cl1;
         }
     } else {
         bh2 = bh1;
     }
 
     /*
      * If we swapped inode order above, we have to swap the buffer heads
      * before passing them back to the caller.
      */
     if (need_swap)
         swap(bh1, bh2);
     *bh_s = bh1;
     *bh_t = bh2;
 
     trace_ocfs2_double_lock_end(
             (unsigned long long)oi1->ip_blkno,
             (unsigned long long)oi2->ip_blkno);
 
     return 0;
 
 out_cl1:
     ocfs2_inode_unlock(inode1, 1);
     brelse(bh1);
 out_rw2:
     ocfs2_rw_unlock(inode2, 1);
 out_i2:
     ocfs2_rw_unlock(inode1, 1);
 out_i1:
     unlock_two_nondirectories(s_inode, t_inode);
     return status;
 }
 
 /* Unlock both inodes and release buffers. */
 void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
                  struct buffer_head *s_bh,
                  struct inode *t_inode,
                  struct buffer_head *t_bh)
 {
     ocfs2_inode_unlock(s_inode, 1);
     ocfs2_rw_unlock(s_inode, 1);
     brelse(s_bh);
     if (s_inode != t_inode) {
         ocfs2_inode_unlock(t_inode, 1);
         ocfs2_rw_unlock(t_inode, 1);
         brelse(t_bh);
     }
     unlock_two_nondirectories(s_inode, t_inode);
 }