Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2

* 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: (28 commits)
  Ocfs2: Teach local-mounted ocfs2 to handle unwritten_extents correctly.
  ocfs2/dlm: Do not migrate resource to a node that is leaving the domain
  ocfs2/dlm: Add new dlm message DLM_BEGIN_EXIT_DOMAIN_MSG
  Ocfs2/move_extents: Set several trivial constraints for threshold.
  Ocfs2/move_extents: Let defrag handle partial extent moving.
  Ocfs2/move_extents: move/defrag extents within a certain range.
  Ocfs2/move_extents: helper to calculate the defraging length in one run.
  Ocfs2/move_extents: move entire/partial extent.
  Ocfs2/move_extents: helpers to update the group descriptor and global bitmap inode.
  Ocfs2/move_extents: helper to probe a proper region to move in an alloc group.
  Ocfs2/move_extents: helper to validate and adjust moving goal.
  Ocfs2/move_extents: find the victim alloc group, where the given #blk fits.
  Ocfs2/move_extents: defrag a range of extent.
  Ocfs2/move_extents: move a range of extent.
  Ocfs2/move_extents: lock allocators and reserve metadata blocks and data clusters for extents moving.
  Ocfs2/move_extents: Add basic framework and source files for extent moving.
  Ocfs2/move_extents: Adding new ioctl code 'OCFS2_IOC_MOVE_EXT' to ocfs2.
  Ocfs2/refcounttree: Publicize couple of funcs from refcounttree.c
  Ocfs2: Add a new code 'OCFS2_INFO_FREEFRAG' for o2info ioctl.
  Ocfs2: Add a new code 'OCFS2_INFO_FREEINODE' for o2info ioctl.
  ...

1 files changed, 1153 insertions, 0 deletions

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
new file mode 100644
index 000000000000..4c5488468c14
--- /dev/null
+++ b/fs/ocfs2/move_extents.c
@@ -0,0 +1,1153 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * move_extents.c
+ *
+ * Copyright (C) 2011 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/mount.h>
+#include <linux/swap.h>
+
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+#include "ocfs2_ioctl.h"
+
+#include "alloc.h"
+#include "aops.h"
+#include "dlmglue.h"
+#include "extent_map.h"
+#include "inode.h"
+#include "journal.h"
+#include "suballoc.h"
+#include "uptodate.h"
+#include "super.h"
+#include "dir.h"
+#include "buffer_head_io.h"
+#include "sysfile.h"
+#include "suballoc.h"
+#include "refcounttree.h"
+#include "move_extents.h"
+
+struct ocfs2_move_extents_context {
+        struct inode *inode;
+        struct file *file;
+        int auto_defrag;
+        int partial;
+        int credits;
+        u32 new_phys_cpos;
+        u32 clusters_moved;
+        u64 refcount_loc;
+        struct ocfs2_move_extents *range;
+        struct ocfs2_extent_tree et;
+        struct ocfs2_alloc_context *meta_ac;
+        struct ocfs2_alloc_context *data_ac;
+        struct ocfs2_cached_dealloc_ctxt dealloc;
+};
+
+static int __ocfs2_move_extent(handle_t *handle,
+                               struct ocfs2_move_extents_context *context,
+                               u32 cpos, u32 len, u32 p_cpos, u32 new_p_cpos,
+                               int ext_flags)
+{
+        int ret = 0, index;
+        struct inode *inode = context->inode;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        struct ocfs2_extent_rec *rec, replace_rec;
+        struct ocfs2_path *path = NULL;
+        struct ocfs2_extent_list *el;
+        u64 ino = ocfs2_metadata_cache_owner(context->et.et_ci);
+        u64 old_blkno = ocfs2_clusters_to_blocks(inode->i_sb, p_cpos);
+
+        ret = ocfs2_duplicate_clusters_by_page(handle, context->file, cpos,
+                                               p_cpos, new_p_cpos, len);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        memset(&replace_rec, 0, sizeof(replace_rec));
+        replace_rec.e_cpos = cpu_to_le32(cpos);
+        replace_rec.e_leaf_clusters = cpu_to_le16(len);
+        replace_rec.e_blkno = cpu_to_le64(ocfs2_clusters_to_blocks(inode->i_sb,
+                                                                   new_p_cpos));
+
+        path = ocfs2_new_path_from_et(&context->et);
+        if (!path) {
+                ret = -ENOMEM;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_find_path(INODE_CACHE(inode), path, cpos);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        el = path_leaf_el(path);
+
+        index = ocfs2_search_extent_list(el, cpos);
+        if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
+                ocfs2_error(inode->i_sb,
+                            "Inode %llu has an extent at cpos %u which can no "
+                            "longer be found.\n",
+                            (unsigned long long)ino, cpos);
+                ret = -EROFS;
+                goto out;
+        }
+
+        rec = &el->l_recs[index];
+
+        BUG_ON(ext_flags != rec->e_flags);
+        /*
+         * after moving/defraging to new location, the extent is not going
+         * to be refcounted anymore.
+         */
+        replace_rec.e_flags = ext_flags & ~OCFS2_EXT_REFCOUNTED;
+
+        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode),
+                                      context->et.et_root_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_split_extent(handle, &context->et, path, index,
+                                 &replace_rec, context->meta_ac,
+                                 &context->dealloc);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ocfs2_journal_dirty(handle, context->et.et_root_bh);
+
+        context->new_phys_cpos = new_p_cpos;
+
+        /*
+         * need I to append truncate log for old clusters?
+         */
+        if (old_blkno) {
+                if (ext_flags & OCFS2_EXT_REFCOUNTED)
+                        ret = ocfs2_decrease_refcount(inode, handle,
+                                        ocfs2_blocks_to_clusters(osb->sb,
+                                                                 old_blkno),
+                                        len, context->meta_ac,
+                                        &context->dealloc, 1);
+                else
+                        ret = ocfs2_truncate_log_append(osb, handle,
+                                                        old_blkno, len);
+        }
+
+out:
+        return ret;
+}
+
+/*
+ * lock allocators, and reserving appropriate number of bits for
+ * meta blocks and data clusters.
+ *
+ * in some cases, we don't need to reserve clusters, just let data_ac
+ * be NULL.
+ */
+static int ocfs2_lock_allocators_move_extents(struct inode *inode,
+                                        struct ocfs2_extent_tree *et,
+                                        u32 clusters_to_move,
+                                        u32 extents_to_split,
+                                        struct ocfs2_alloc_context **meta_ac,
+                                        struct ocfs2_alloc_context **data_ac,
+                                        int extra_blocks,
+                                        int *credits)
+{
+        int ret, num_free_extents;
+        unsigned int max_recs_needed = 2 * extents_to_split + clusters_to_move;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        num_free_extents = ocfs2_num_free_extents(osb, et);
+        if (num_free_extents < 0) {
+                ret = num_free_extents;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        if (!num_free_extents ||
+            (ocfs2_sparse_alloc(osb) && num_free_extents < max_recs_needed))
+                extra_blocks += ocfs2_extend_meta_needed(et->et_root_el);
+
+        ret = ocfs2_reserve_new_metadata_blocks(osb, extra_blocks, meta_ac);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        if (data_ac) {
+                ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+        }
+
+        *credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el,
+                                              clusters_to_move + 2);
+
+        mlog(0, "reserve metadata_blocks: %d, data_clusters: %u, credits: %d\n",
+             extra_blocks, clusters_to_move, *credits);
+out:
+        if (ret) {
+                if (*meta_ac) {
+                        ocfs2_free_alloc_context(*meta_ac);
+                        *meta_ac = NULL;
+                }
+        }
+
+        return ret;
+}
+
+/*
+ * Using one journal handle to guarantee the data consistency in case
+ * crash happens anywhere.
+ *
+ *  XXX: defrag can end up with finishing partial extent as requested,
+ * due to not enough contiguous clusters can be found in allocator.
+ */
+static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
+                               u32 cpos, u32 phys_cpos, u32 *len, int ext_flags)
+{
+        int ret, credits = 0, extra_blocks = 0, partial = context->partial;
+        handle_t *handle;
+        struct inode *inode = context->inode;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        struct inode *tl_inode = osb->osb_tl_inode;
+        struct ocfs2_refcount_tree *ref_tree = NULL;
+        u32 new_phys_cpos, new_len;
+        u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
+
+        if ((ext_flags & OCFS2_EXT_REFCOUNTED) && *len) {
+
+                BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
+                         OCFS2_HAS_REFCOUNT_FL));
+
+                BUG_ON(!context->refcount_loc);
+
+                ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
+                                               &ref_tree, NULL);
+                if (ret) {
+                        mlog_errno(ret);
+                        return ret;
+                }
+
+                ret = ocfs2_prepare_refcount_change_for_del(inode,
+                                                        context->refcount_loc,
+                                                        phys_blkno,
+                                                        *len,
+                                                        &credits,
+                                                        &extra_blocks);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+        }
+
+        ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
+                                                 &context->meta_ac,
+                                                 &context->data_ac,
+                                                 extra_blocks, &credits);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /*
+         * should be using allocation reservation strategy there?
+         *
+         * if (context->data_ac)
+         *      context->data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
+         */
+
+        mutex_lock(&tl_inode->i_mutex);
+
+        if (ocfs2_truncate_log_needs_flush(osb)) {
+                ret = __ocfs2_flush_truncate_log(osb);
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        goto out_unlock_mutex;
+                }
+        }
+
+        handle = ocfs2_start_trans(osb, credits);
+        if (IS_ERR(handle)) {
+                ret = PTR_ERR(handle);
+                mlog_errno(ret);
+                goto out_unlock_mutex;
+        }
+
+        ret = __ocfs2_claim_clusters(handle, context->data_ac, 1, *len,
+                                     &new_phys_cpos, &new_len);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_commit;
+        }
+
+        /*
+         * allowing partial extent moving is kind of 'pros and cons', it makes
+         * whole defragmentation less likely to fail, on the contrary, the bad
+         * thing is it may make the fs even more fragmented after moving, let
+         * userspace make a good decision here.
+         */
+        if (new_len != *len) {
+                mlog(0, "len_claimed: %u, len: %u\n", new_len, *len);
+                if (!partial) {
+                        context->range->me_flags &= ~OCFS2_MOVE_EXT_FL_COMPLETE;
+                        ret = -ENOSPC;
+                        goto out_commit;
+                }
+        }
+
+        mlog(0, "cpos: %u, phys_cpos: %u, new_phys_cpos: %u\n", cpos,
+             phys_cpos, new_phys_cpos);
+
+        ret = __ocfs2_move_extent(handle, context, cpos, new_len, phys_cpos,
+                                  new_phys_cpos, ext_flags);
+        if (ret)
+                mlog_errno(ret);
+
+        if (partial && (new_len != *len))
+                *len = new_len;
+
+        /*
+         * Here we should write the new page out first if we are
+         * in write-back mode.
+         */
+        ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, *len);
+        if (ret)
+                mlog_errno(ret);
+
+out_commit:
+        ocfs2_commit_trans(osb, handle);
+
+out_unlock_mutex:
+        mutex_unlock(&tl_inode->i_mutex);
+
+        if (context->data_ac) {
+                ocfs2_free_alloc_context(context->data_ac);
+                context->data_ac = NULL;
+        }
+
+        if (context->meta_ac) {
+                ocfs2_free_alloc_context(context->meta_ac);
+                context->meta_ac = NULL;
+        }
+
+out:
+        if (ref_tree)
+                ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
+
+        return ret;
+}
+
+/*
+ * find the victim alloc group, where #blkno fits.
+ */
+static int ocfs2_find_victim_alloc_group(struct inode *inode,
+                                         u64 vict_blkno,
+                                         int type, int slot,
+                                         int *vict_bit,
+                                         struct buffer_head **ret_bh)
+{
+        int ret, i, blocks_per_unit = 1;
+        u64 blkno;
+        char namebuf[40];
+
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        struct buffer_head *ac_bh = NULL, *gd_bh = NULL;
+        struct ocfs2_chain_list *cl;
+        struct ocfs2_chain_rec *rec;
+        struct ocfs2_dinode *ac_dinode;
+        struct ocfs2_group_desc *bg;
+
+        ocfs2_sprintf_system_inode_name(namebuf, sizeof(namebuf), type, slot);
+        ret = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
+                                         strlen(namebuf), &blkno);
+        if (ret) {
+                ret = -ENOENT;
+                goto out;
+        }
+
+        ret = ocfs2_read_blocks_sync(osb, blkno, 1, &ac_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ac_dinode = (struct ocfs2_dinode *)ac_bh->b_data;
+        cl = &(ac_dinode->id2.i_chain);
+        rec = &(cl->cl_recs[0]);
+
+        if (type == GLOBAL_BITMAP_SYSTEM_INODE)
+                blocks_per_unit <<= (osb->s_clustersize_bits -
+                                                inode->i_sb->s_blocksize_bits);
+        /*
+         * 'vict_blkno' was out of the valid range.
+         */
+        if ((vict_blkno < le64_to_cpu(rec->c_blkno)) ||
+            (vict_blkno >= (le32_to_cpu(ac_dinode->id1.bitmap1.i_total) *
+                                blocks_per_unit))) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i++) {
+
+                rec = &(cl->cl_recs[i]);
+                if (!rec)
+                        continue;
+
+                bg = NULL;
+
+                do {
+                        if (!bg)
+                                blkno = le64_to_cpu(rec->c_blkno);
+                        else
+                                blkno = le64_to_cpu(bg->bg_next_group);
+
+                        if (gd_bh) {
+                                brelse(gd_bh);
+                                gd_bh = NULL;
+                        }
+
+                        ret = ocfs2_read_blocks_sync(osb, blkno, 1, &gd_bh);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+
+                        bg = (struct ocfs2_group_desc *)gd_bh->b_data;
+
+                        if (vict_blkno < (le64_to_cpu(bg->bg_blkno) +
+                                                le16_to_cpu(bg->bg_bits))) {
+
+                                *ret_bh = gd_bh;
+                                *vict_bit = (vict_blkno - blkno) /
+                                                        blocks_per_unit;
+                                mlog(0, "find the victim group: #%llu, "
+                                     "total_bits: %u, vict_bit: %u\n",
+                                     blkno, le16_to_cpu(bg->bg_bits),
+                                     *vict_bit);
+                                goto out;
+                        }
+
+                } while (le64_to_cpu(bg->bg_next_group));
+        }
+
+        ret = -EINVAL;
+out:
+        brelse(ac_bh);
+
+        /*
+         * caller has to release the gd_bh properly.
+         */
+        return ret;
+}
+
+/*
+ * XXX: helper to validate and adjust moving goal.
+ */
+static int ocfs2_validate_and_adjust_move_goal(struct inode *inode,
+                                               struct ocfs2_move_extents *range)
+{
+        int ret, goal_bit = 0;
+
+        struct buffer_head *gd_bh = NULL;
+        struct ocfs2_group_desc *bg;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        int c_to_b = 1 << (osb->s_clustersize_bits -
+                                        inode->i_sb->s_blocksize_bits);
+
+        /*
+         * validate goal sits within global_bitmap, and return the victim
+         * group desc
+         */
+        ret = ocfs2_find_victim_alloc_group(inode, range->me_goal,
+                                            GLOBAL_BITMAP_SYSTEM_INODE,
+                                            OCFS2_INVALID_SLOT,
+                                            &goal_bit, &gd_bh);
+        if (ret)
+                goto out;
+
+        bg = (struct ocfs2_group_desc *)gd_bh->b_data;
+
+        /*
+         * make goal become cluster aligned.
+         */
+        if (range->me_goal % c_to_b)
+                range->me_goal = range->me_goal / c_to_b * c_to_b;
+
+        /*
+         * moving goal is not allowd to start with a group desc blok(#0 blk)
+         * let's compromise to the latter cluster.
+         */
+        if (range->me_goal == le64_to_cpu(bg->bg_blkno))
+                range->me_goal += c_to_b;
+
+        /*
+         * movement is not gonna cross two groups.
+         */
+        if ((le16_to_cpu(bg->bg_bits) - goal_bit) * osb->s_clustersize <
+                                                                range->me_len) {
+                ret = -EINVAL;
+                goto out;
+        }
+        /*
+         * more exact validations/adjustments will be performed later during
+         * moving operation for each extent range.
+         */
+        mlog(0, "extents get ready to be moved to #%llu block\n",
+             range->me_goal);
+
+out:
+        brelse(gd_bh);
+
+        return ret;
+}
+
+static void ocfs2_probe_alloc_group(struct inode *inode, struct buffer_head *bh,
+                                    int *goal_bit, u32 move_len, u32 max_hop,
+                                    u32 *phys_cpos)
+{
+        int i, used, last_free_bits = 0, base_bit = *goal_bit;
+        struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+        u32 base_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
+                                                 le64_to_cpu(gd->bg_blkno));
+
+        for (i = base_bit; i < le16_to_cpu(gd->bg_bits); i++) {
+
+                used = ocfs2_test_bit(i, (unsigned long *)gd->bg_bitmap);
+                if (used) {
+                        /*
+                         * we even tried searching the free chunk by jumping
+                         * a 'max_hop' distance, but still failed.
+                         */
+                        if ((i - base_bit) > max_hop) {
+                                *phys_cpos = 0;
+                                break;
+                        }
+
+                        if (last_free_bits)
+                                last_free_bits = 0;
+
+                        continue;
+                } else
+                        last_free_bits++;
+
+                if (last_free_bits == move_len) {
+                        *goal_bit = i;
+                        *phys_cpos = base_cpos + i;
+                        break;
+                }
+        }
+
+        mlog(0, "found phys_cpos: %u to fit the wanted moving.\n", *phys_cpos);
+}
+
+static int ocfs2_alloc_dinode_update_counts(struct inode *inode,
+                                       handle_t *handle,
+                                       struct buffer_head *di_bh,
+                                       u32 num_bits,
+                                       u16 chain)
+{
+        int ret;
+        u32 tmp_used;
+        struct ocfs2_dinode *di = (struct ocfs2_dinode *) di_bh->b_data;
+        struct ocfs2_chain_list *cl =
+                                (struct ocfs2_chain_list *) &di->id2.i_chain;
+
+        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        tmp_used = le32_to_cpu(di->id1.bitmap1.i_used);
+        di->id1.bitmap1.i_used = cpu_to_le32(num_bits + tmp_used);
+        le32_add_cpu(&cl->cl_recs[chain].c_free, -num_bits);
+        ocfs2_journal_dirty(handle, di_bh);
+
+out:
+        return ret;
+}
+
+static inline int ocfs2_block_group_set_bits(handle_t *handle,
+                                             struct inode *alloc_inode,
+                                             struct ocfs2_group_desc *bg,
+                                             struct buffer_head *group_bh,
+                                             unsigned int bit_off,
+                                             unsigned int num_bits)
+{
+        int status;
+        void *bitmap = bg->bg_bitmap;
+        int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
+
+        /* All callers get the descriptor via
+         * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
+        BUG_ON(!OCFS2_IS_VALID_GROUP_DESC(bg));
+        BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);
+
+        mlog(0, "block_group_set_bits: off = %u, num = %u\n", bit_off,
+             num_bits);
+
+        if (ocfs2_is_cluster_bitmap(alloc_inode))
+                journal_type = OCFS2_JOURNAL_ACCESS_UNDO;
+
+        status = ocfs2_journal_access_gd(handle,
+                                         INODE_CACHE(alloc_inode),
+                                         group_bh,
+                                         journal_type);
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        le16_add_cpu(&bg->bg_free_bits_count, -num_bits);
+        if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
+                ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit"
+                            " count %u but claims %u are freed. num_bits %d",
+                            (unsigned long long)le64_to_cpu(bg->bg_blkno),
+                            le16_to_cpu(bg->bg_bits),
+                            le16_to_cpu(bg->bg_free_bits_count), num_bits);
+                return -EROFS;
+        }
+        while (num_bits--)
+                ocfs2_set_bit(bit_off++, bitmap);
+
+        ocfs2_journal_dirty(handle, group_bh);
+
+bail:
+        return status;
+}
+
+static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
+                             u32 cpos, u32 phys_cpos, u32 *new_phys_cpos,
+                             u32 len, int ext_flags)
+{
+        int ret, credits = 0, extra_blocks = 0, goal_bit = 0;
+        handle_t *handle;
+        struct inode *inode = context->inode;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        struct inode *tl_inode = osb->osb_tl_inode;
+        struct inode *gb_inode = NULL;
+        struct buffer_head *gb_bh = NULL;
+        struct buffer_head *gd_bh = NULL;
+        struct ocfs2_group_desc *gd;
+        struct ocfs2_refcount_tree *ref_tree = NULL;
+        u32 move_max_hop = ocfs2_blocks_to_clusters(inode->i_sb,
+                                                    context->range->me_threshold);
+        u64 phys_blkno, new_phys_blkno;
+
+        phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
+
+        if ((ext_flags & OCFS2_EXT_REFCOUNTED) && len) {
+
+                BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
+                         OCFS2_HAS_REFCOUNT_FL));
+
+                BUG_ON(!context->refcount_loc);
+
+                ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
+                                               &ref_tree, NULL);
+                if (ret) {
+                        mlog_errno(ret);
+                        return ret;
+                }
+
+                ret = ocfs2_prepare_refcount_change_for_del(inode,
+                                                        context->refcount_loc,
+                                                        phys_blkno,
+                                                        len,
+                                                        &credits,
+                                                        &extra_blocks);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+        }
+
+        ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
+                                                 &context->meta_ac,
+                                                 NULL, extra_blocks, &credits);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /*
+         * need to count 2 extra credits for global_bitmap inode and
+         * group descriptor.
+         */
+        credits += OCFS2_INODE_UPDATE_CREDITS + 1;
+
+        /*
+         * ocfs2_move_extent() didn't reserve any clusters in lock_allocators()
+         * logic, while we still need to lock the global_bitmap.
+         */
+        gb_inode = ocfs2_get_system_file_inode(osb, GLOBAL_BITMAP_SYSTEM_INODE,
+                                               OCFS2_INVALID_SLOT);
+        if (!gb_inode) {
+                mlog(ML_ERROR, "unable to get global_bitmap inode\n");
+                ret = -EIO;
+                goto out;
+        }
+
+        mutex_lock(&gb_inode->i_mutex);
+
+        ret = ocfs2_inode_lock(gb_inode, &gb_bh, 1);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_unlock_gb_mutex;
+        }
+
+        mutex_lock(&tl_inode->i_mutex);
+
+        handle = ocfs2_start_trans(osb, credits);
+        if (IS_ERR(handle)) {
+                ret = PTR_ERR(handle);
+                mlog_errno(ret);
+                goto out_unlock_tl_inode;
+        }
+
+        new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
+        ret = ocfs2_find_victim_alloc_group(inode, new_phys_blkno,
+                                            GLOBAL_BITMAP_SYSTEM_INODE,
+                                            OCFS2_INVALID_SLOT,
+                                            &goal_bit, &gd_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_commit;
+        }
+
+        /*
+         * probe the victim cluster group to find a proper
+         * region to fit wanted movement, it even will perfrom
+         * a best-effort attempt by compromising to a threshold
+         * around the goal.
+         */
+        ocfs2_probe_alloc_group(inode, gd_bh, &goal_bit, len, move_max_hop,
+                                new_phys_cpos);
+        if (!new_phys_cpos) {
+                ret = -ENOSPC;
+                goto out_commit;
+        }
+
+        ret = __ocfs2_move_extent(handle, context, cpos, len, phys_cpos,
+                                  *new_phys_cpos, ext_flags);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_commit;
+        }
+
+        gd = (struct ocfs2_group_desc *)gd_bh->b_data;
+        ret = ocfs2_alloc_dinode_update_counts(gb_inode, handle, gb_bh, len,
+                                               le16_to_cpu(gd->bg_chain));
+        if (ret) {
+                mlog_errno(ret);
+                goto out_commit;
+        }
+
+        ret = ocfs2_block_group_set_bits(handle, gb_inode, gd, gd_bh,
+                                         goal_bit, len);
+        if (ret)
+                mlog_errno(ret);
+
+        /*
+         * Here we should write the new page out first if we are
+         * in write-back mode.
+         */
+        ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, len);
+        if (ret)
+                mlog_errno(ret);
+
+out_commit:
+        ocfs2_commit_trans(osb, handle);
+        brelse(gd_bh);
+
+out_unlock_tl_inode:
+        mutex_unlock(&tl_inode->i_mutex);
+
+        ocfs2_inode_unlock(gb_inode, 1);
+out_unlock_gb_mutex:
+        mutex_unlock(&gb_inode->i_mutex);
+        brelse(gb_bh);
+        iput(gb_inode);
+
+out:
+        if (context->meta_ac) {
+                ocfs2_free_alloc_context(context->meta_ac);
+                context->meta_ac = NULL;
+        }
+
+        if (ref_tree)
+                ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
+
+        return ret;
+}
+
+/*
+ * Helper to calculate the defraging length in one run according to threshold.
+ */
+static void ocfs2_calc_extent_defrag_len(u32 *alloc_size, u32 *len_defraged,
+                                         u32 threshold, int *skip)
+{
+        if ((*alloc_size + *len_defraged) < threshold) {
+                /*
+                 * proceed defragmentation until we meet the thresh
+                 */
+                *len_defraged += *alloc_size;
+        } else if (*len_defraged == 0) {
+                /*
+                 * XXX: skip a large extent.
+                 */
+                *skip = 1;
+        } else {
+                /*
+                 * split this extent to coalesce with former pieces as
+                 * to reach the threshold.
+                 *
+                 * we're done here with one cycle of defragmentation
+                 * in a size of 'thresh', resetting 'len_defraged'
+                 * forces a new defragmentation.
+                 */
+                *alloc_size = threshold - *len_defraged;
+                *len_defraged = 0;
+        }
+}
+
+static int __ocfs2_move_extents_range(struct buffer_head *di_bh,
+                                struct ocfs2_move_extents_context *context)
+{
+        int ret = 0, flags, do_defrag, skip = 0;
+        u32 cpos, phys_cpos, move_start, len_to_move, alloc_size;
+        u32 len_defraged = 0, defrag_thresh = 0, new_phys_cpos = 0;
+
+        struct inode *inode = context->inode;
+        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
+        struct ocfs2_move_extents *range = context->range;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if ((inode->i_size == 0) || (range->me_len == 0))
+                return 0;
+
+        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+                return 0;
+
+        context->refcount_loc = le64_to_cpu(di->i_refcount_loc);
+
+        ocfs2_init_dinode_extent_tree(&context->et, INODE_CACHE(inode), di_bh);
+        ocfs2_init_dealloc_ctxt(&context->dealloc);
+
+        /*
+         * TO-DO XXX:
+         *
+         * - xattr extents.
+         */
+
+        do_defrag = context->auto_defrag;
+
+        /*
+         * extents moving happens in unit of clusters, for the sake
+         * of simplicity, we may ignore two clusters where 'byte_start'
+         * and 'byte_start + len' were within.
+         */
+        move_start = ocfs2_clusters_for_bytes(osb->sb, range->me_start);
+        len_to_move = (range->me_start + range->me_len) >>
+                                                osb->s_clustersize_bits;
+        if (len_to_move >= move_start)
+                len_to_move -= move_start;
+        else
+                len_to_move = 0;
+
+        if (do_defrag) {
+                defrag_thresh = range->me_threshold >> osb->s_clustersize_bits;
+                if (defrag_thresh <= 1)
+                        goto done;
+        } else
+                new_phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
+                                                         range->me_goal);
+
+        mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: %u, "
+             "thresh: %u\n",
+             (unsigned long long)OCFS2_I(inode)->ip_blkno,
+             (unsigned long long)range->me_start,
+             (unsigned long long)range->me_len,
+             move_start, len_to_move, defrag_thresh);
+
+        cpos = move_start;
+        while (len_to_move) {
+                ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &alloc_size,
+                                         &flags);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                if (alloc_size > len_to_move)
+                        alloc_size = len_to_move;
+
+                /*
+                 * XXX: how to deal with a hole:
+                 *
+                 * - skip the hole of course
+                 * - force a new defragmentation
+                 */
+                if (!phys_cpos) {
+                        if (do_defrag)
+                                len_defraged = 0;
+
+                        goto next;
+                }
+
+                if (do_defrag) {
+                        ocfs2_calc_extent_defrag_len(&alloc_size, &len_defraged,
+                                                     defrag_thresh, &skip);
+                        /*
+                         * skip large extents
+                         */
+                        if (skip) {
+                                skip = 0;
+                                goto next;
+                        }
+
+                        mlog(0, "#Defrag: cpos: %u, phys_cpos: %u, "
+                             "alloc_size: %u, len_defraged: %u\n",
+                             cpos, phys_cpos, alloc_size, len_defraged);
+
+                        ret = ocfs2_defrag_extent(context, cpos, phys_cpos,
+                                                  &alloc_size, flags);
+                } else {
+                        ret = ocfs2_move_extent(context, cpos, phys_cpos,
+                                                &new_phys_cpos, alloc_size,
+                                                flags);
+
+                        new_phys_cpos += alloc_size;
+                }
+
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                context->clusters_moved += alloc_size;
+next:
+                cpos += alloc_size;
+                len_to_move -= alloc_size;
+        }
+
+done:
+        range->me_flags |= OCFS2_MOVE_EXT_FL_COMPLETE;
+
+out:
+        range->me_moved_len = ocfs2_clusters_to_bytes(osb->sb,
+                                                      context->clusters_moved);
+        range->me_new_offset = ocfs2_clusters_to_bytes(osb->sb,
+                                                       context->new_phys_cpos);
+
+        ocfs2_schedule_truncate_log_flush(osb, 1);
+        ocfs2_run_deallocs(osb, &context->dealloc);
+
+        return ret;
+}
+
+static int ocfs2_move_extents(struct ocfs2_move_extents_context *context)
+{
+        int status;
+        handle_t *handle;
+        struct inode *inode = context->inode;
+        struct ocfs2_dinode *di;
+        struct buffer_head *di_bh = NULL;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (!inode)
+                return -ENOENT;
+
+        if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
+                return -EROFS;
+
+        mutex_lock(&inode->i_mutex);
+
+        /*
+         * This prevents concurrent writes from other nodes
+         */
+        status = ocfs2_rw_lock(inode, 1);
+        if (status) {
+                mlog_errno(status);
+                goto out;
+        }
+
+        status = ocfs2_inode_lock(inode, &di_bh, 1);
+        if (status) {
+                mlog_errno(status);
+                goto out_rw_unlock;
+        }
+
+        /*
+         * rememer ip_xattr_sem also needs to be held if necessary
+         */
+        down_write(&OCFS2_I(inode)->ip_alloc_sem);
+
+        status = __ocfs2_move_extents_range(di_bh, context);
+
+        up_write(&OCFS2_I(inode)->ip_alloc_sem);
+        if (status) {
+                mlog_errno(status);
+                goto out_inode_unlock;
+        }
+
+        /*
+         * We update ctime for these changes
+         */
+        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
+        if (IS_ERR(handle)) {
+                status = PTR_ERR(handle);
+                mlog_errno(status);
+                goto out_inode_unlock;
+        }
+
+        status = ocfs2_journal_access_di(handle, INODE_CACHE(inode), di_bh,
+                                         OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status) {
+                mlog_errno(status);
+                goto out_commit;
+        }
+
+        di = (struct ocfs2_dinode *)di_bh->b_data;
+        inode->i_ctime = CURRENT_TIME;
+        di->i_ctime = cpu_to_le64(inode->i_ctime.tv_sec);
+        di->i_ctime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
+
+        ocfs2_journal_dirty(handle, di_bh);
+
+out_commit:
+        ocfs2_commit_trans(osb, handle);
+
+out_inode_unlock:
+        brelse(di_bh);
+        ocfs2_inode_unlock(inode, 1);
+out_rw_unlock:
+        ocfs2_rw_unlock(inode, 1);
+out:
+        mutex_unlock(&inode->i_mutex);
+
+        return status;
+}
+
+int ocfs2_ioctl_move_extents(struct file *filp, void __user *argp)
+{
+        int status;
+
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        struct ocfs2_move_extents range;
+        struct ocfs2_move_extents_context *context = NULL;
+
+        status = mnt_want_write(filp->f_path.mnt);
+        if (status)
+                return status;
+
+        if ((!S_ISREG(inode->i_mode)) || !(filp->f_mode & FMODE_WRITE))
+                goto out;
+
+        if (inode->i_flags & (S_IMMUTABLE|S_APPEND)) {
+                status = -EPERM;
+                goto out;
+        }
+
+        context = kzalloc(sizeof(struct ocfs2_move_extents_context), GFP_NOFS);
+        if (!context) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto out;
+        }
+
+        context->inode = inode;
+        context->file = filp;
+
+        if (argp) {
+                if (copy_from_user(&range, (struct ocfs2_move_extents *)argp,
+                                   sizeof(range))) {
+                        status = -EFAULT;
+                        goto out;
+                }
+        } else {
+                status = -EINVAL;
+                goto out;
+        }
+
+        if (range.me_start > i_size_read(inode))
+                goto out;
+
+        if (range.me_start + range.me_len > i_size_read(inode))
+                        range.me_len = i_size_read(inode) - range.me_start;
+
+        context->range = &range;
+
+        if (range.me_flags & OCFS2_MOVE_EXT_FL_AUTO_DEFRAG) {
+                context->auto_defrag = 1;
+                /*
+                 * ok, the default theshold for the defragmentation
+                 * is 1M, since our maximum clustersize was 1M also.
+                 * any thought?
+                 */
+                if (!range.me_threshold)
+                        range.me_threshold = 1024 * 1024;
+
+                if (range.me_threshold > i_size_read(inode))
+                        range.me_threshold = i_size_read(inode);
+
+                if (range.me_flags & OCFS2_MOVE_EXT_FL_PART_DEFRAG)
+                        context->partial = 1;
+        } else {
+                /*
+                 * first best-effort attempt to validate and adjust the goal
+                 * (physical address in block), while it can't guarantee later
+                 * operation can succeed all the time since global_bitmap may
+                 * change a bit over time.
+                 */
+
+                status = ocfs2_validate_and_adjust_move_goal(inode, &range);
+                if (status)
+                        goto out;
+        }
+
+        status = ocfs2_move_extents(context);
+        if (status)
+                mlog_errno(status);
+out:
+        /*
+         * movement/defragmentation may end up being partially completed,
+         * that's the reason why we need to return userspace the finished
+         * length and new_offset even if failure happens somewhere.
+         */
+        if (argp) {
+                if (copy_to_user((struct ocfs2_move_extents *)argp, &range,
+                                sizeof(range)))
+                        status = -EFAULT;
+        }
+
+        kfree(context);
+
+        mnt_drop_write(filp->f_path.mnt);
+
+        return status;
+}