Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / fs / ocfs2 / move_extents.c
diff --git a/kernel/fs/ocfs2/move_extents.c b/kernel/fs/ocfs2/move_extents.c
new file mode 100644 (file)
index 0000000..56a768d
--- /dev/null
@@ -0,0 +1,1075 @@
+/* -*- 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 "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, inode, 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) {
+               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);
+       }
+
+       ocfs2_update_inode_fsync_trans(handle, inode, 0);
+out:
+       ocfs2_free_path(path);
+       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);
+
+       mlog(0, "reserve metadata_blocks: %d, data_clusters: %u, credits: %d\n",
+            extra_blocks, clusters_to_move, *credits);
+out:
+       if (ret) {
+               if (*meta_ac) {
+                       ocfs2_free_alloc_context(*meta_ac);
+                       *meta_ac = NULL;
+               }
+       }
+
+       return ret;
+}
+
+/*
+ * Using one journal handle to guarantee the data consistency in case
+ * crash happens anywhere.
+ *
+ *  XXX: defrag can end up with finishing partial extent as requested,
+ * due to not enough contiguous clusters can be found in allocator.
+ */
+static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
+                              u32 cpos, u32 phys_cpos, u32 *len, int ext_flags)
+{
+       int ret, credits = 0, extra_blocks = 0, partial = context->partial;
+       handle_t *handle;
+       struct inode *inode = context->inode;
+       struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+       struct inode *tl_inode = osb->osb_tl_inode;
+       struct ocfs2_refcount_tree *ref_tree = NULL;
+       u32 new_phys_cpos, new_len;
+       u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
+
+       if ((ext_flags & OCFS2_EXT_REFCOUNTED) && *len) {
+
+               BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
+                        OCFS2_HAS_REFCOUNT_FL));
+
+               BUG_ON(!context->refcount_loc);
+
+               ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
+                                              &ref_tree, NULL);
+               if (ret) {
+                       mlog_errno(ret);
+                       return ret;
+               }
+
+               ret = ocfs2_prepare_refcount_change_for_del(inode,
+                                                       context->refcount_loc,
+                                                       phys_blkno,
+                                                       *len,
+                                                       &credits,
+                                                       &extra_blocks);
+               if (ret) {
+                       mlog_errno(ret);
+                       goto out;
+               }
+       }
+
+       ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
+                                                &context->meta_ac,
+                                                &context->data_ac,
+                                                extra_blocks, &credits);
+       if (ret) {
+               mlog_errno(ret);
+               goto out;
+       }
+
+       /*
+        * should be using allocation reservation strategy there?
+        *
+        * if (context->data_ac)
+        *      context->data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
+        */
+
+       mutex_lock(&tl_inode->i_mutex);
+
+       if (ocfs2_truncate_log_needs_flush(osb)) {
+               ret = __ocfs2_flush_truncate_log(osb);
+               if (ret < 0) {
+                       mlog_errno(ret);
+                       goto out_unlock_mutex;
+               }
+       }
+
+       handle = ocfs2_start_trans(osb, credits);
+       if (IS_ERR(handle)) {
+               ret = PTR_ERR(handle);
+               mlog_errno(ret);
+               goto out_unlock_mutex;
+       }
+
+       ret = __ocfs2_claim_clusters(handle, context->data_ac, 1, *len,
+                                    &new_phys_cpos, &new_len);
+       if (ret) {
+               mlog_errno(ret);
+               goto out_commit;
+       }
+
+       /*
+        * allowing partial extent moving is kind of 'pros and cons', it makes
+        * whole defragmentation less likely to fail, on the contrary, the bad
+        * thing is it may make the fs even more fragmented after moving, let
+        * userspace make a good decision here.
+        */
+       if (new_len != *len) {
+               mlog(0, "len_claimed: %u, len: %u\n", new_len, *len);
+               if (!partial) {
+                       context->range->me_flags &= ~OCFS2_MOVE_EXT_FL_COMPLETE;
+                       ret = -ENOSPC;
+                       goto out_commit;
+               }
+       }
+
+       mlog(0, "cpos: %u, phys_cpos: %u, new_phys_cpos: %u\n", cpos,
+            phys_cpos, new_phys_cpos);
+
+       ret = __ocfs2_move_extent(handle, context, cpos, new_len, phys_cpos,
+                                 new_phys_cpos, ext_flags);
+       if (ret)
+               mlog_errno(ret);
+
+       if (partial && (new_len != *len))
+               *len = new_len;
+
+       /*
+        * Here we should write the new page out first if we are
+        * in write-back mode.
+        */
+       ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, *len);
+       if (ret)
+               mlog_errno(ret);
+
+out_commit:
+       ocfs2_commit_trans(osb, handle);
+
+out_unlock_mutex:
+       mutex_unlock(&tl_inode->i_mutex);
+
+       if (context->data_ac) {
+               ocfs2_free_alloc_context(context->data_ac);
+               context->data_ac = NULL;
+       }
+
+       if (context->meta_ac) {
+               ocfs2_free_alloc_context(context->meta_ac);
+               context->meta_ac = NULL;
+       }
+
+out:
+       if (ref_tree)
+               ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
+
+       return ret;
+}
+
+/*
+ * find the victim alloc group, where #blkno fits.
+ */
+static int ocfs2_find_victim_alloc_group(struct inode *inode,
+                                        u64 vict_blkno,
+                                        int type, int slot,
+                                        int *vict_bit,
+                                        struct buffer_head **ret_bh)
+{
+       int ret, i, bits_per_unit = 0;
+       u64 blkno;
+       char namebuf[40];
+
+       struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+       struct buffer_head *ac_bh = NULL, *gd_bh = NULL;
+       struct ocfs2_chain_list *cl;
+       struct ocfs2_chain_rec *rec;
+       struct ocfs2_dinode *ac_dinode;
+       struct ocfs2_group_desc *bg;
+
+       ocfs2_sprintf_system_inode_name(namebuf, sizeof(namebuf), type, slot);
+       ret = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
+                                        strlen(namebuf), &blkno);
+       if (ret) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       ret = ocfs2_read_blocks_sync(osb, blkno, 1, &ac_bh);
+       if (ret) {
+               mlog_errno(ret);
+               goto out;
+       }
+
+       ac_dinode = (struct ocfs2_dinode *)ac_bh->b_data;
+       cl = &(ac_dinode->id2.i_chain);
+       rec = &(cl->cl_recs[0]);
+
+       if (type == GLOBAL_BITMAP_SYSTEM_INODE)
+               bits_per_unit = osb->s_clustersize_bits -
+                                       inode->i_sb->s_blocksize_bits;
+       /*
+        * 'vict_blkno' was out of the valid range.
+        */
+       if ((vict_blkno < le64_to_cpu(rec->c_blkno)) ||
+           (vict_blkno >= ((u64)le32_to_cpu(ac_dinode->id1.bitmap1.i_total) <<
+                               bits_per_unit))) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i++) {
+
+               rec = &(cl->cl_recs[i]);
+               if (!rec)
+                       continue;
+
+               bg = NULL;
+
+               do {
+                       if (!bg)
+                               blkno = le64_to_cpu(rec->c_blkno);
+                       else
+                               blkno = le64_to_cpu(bg->bg_next_group);
+
+                       if (gd_bh) {
+                               brelse(gd_bh);
+                               gd_bh = NULL;
+                       }
+
+                       ret = ocfs2_read_blocks_sync(osb, blkno, 1, &gd_bh);
+                       if (ret) {
+                               mlog_errno(ret);
+                               goto out;
+                       }
+
+                       bg = (struct ocfs2_group_desc *)gd_bh->b_data;
+
+                       if (vict_blkno < (le64_to_cpu(bg->bg_blkno) +
+                                               le16_to_cpu(bg->bg_bits))) {
+
+                               *ret_bh = gd_bh;
+                               *vict_bit = (vict_blkno - blkno) >>
+                                                       bits_per_unit;
+                               mlog(0, "find the victim group: #%llu, "
+                                    "total_bits: %u, vict_bit: %u\n",
+                                    blkno, le16_to_cpu(bg->bg_bits),
+                                    *vict_bit);
+                               goto out;
+                       }
+
+               } while (le64_to_cpu(bg->bg_next_group));
+       }
+
+       ret = -EINVAL;
+out:
+       brelse(ac_bh);
+
+       /*
+        * caller has to release the gd_bh properly.
+        */
+       return ret;
+}
+
+/*
+ * XXX: helper to validate and adjust moving goal.
+ */
+static int ocfs2_validate_and_adjust_move_goal(struct inode *inode,
+                                              struct ocfs2_move_extents *range)
+{
+       int ret, goal_bit = 0;
+
+       struct buffer_head *gd_bh = NULL;
+       struct ocfs2_group_desc *bg;
+       struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+       int c_to_b = 1 << (osb->s_clustersize_bits -
+                                       inode->i_sb->s_blocksize_bits);
+
+       /*
+        * make goal become cluster aligned.
+        */
+       range->me_goal = ocfs2_block_to_cluster_start(inode->i_sb,
+                                                     range->me_goal);
+       /*
+        * 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;
+
+       /*
+        * 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_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) {
+               ocfs2_rollback_alloc_dinode_counts(gb_inode, gb_bh, len,
+                                              le16_to_cpu(gd->bg_chain));
+               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 ((i_size_read(inode) == 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 (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_update_inode_fsync_trans(handle, inode, 0);
+
+       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 = file_inode(filp);
+       struct ocfs2_move_extents range;
+       struct ocfs2_move_extents_context *context;
+
+       if (!argp)
+               return -EINVAL;
+
+       status = mnt_want_write_file(filp);
+       if (status)
+               return status;
+
+       if ((!S_ISREG(inode->i_mode)) || !(filp->f_mode & FMODE_WRITE)) {
+               status = -EPERM;
+               goto out_drop;
+       }
+
+       if (inode->i_flags & (S_IMMUTABLE|S_APPEND)) {
+               status = -EPERM;
+               goto out_drop;
+       }
+
+       context = kzalloc(sizeof(struct ocfs2_move_extents_context), GFP_NOFS);
+       if (!context) {
+               status = -ENOMEM;
+               mlog_errno(status);
+               goto out_drop;
+       }
+
+       context->inode = inode;
+       context->file = filp;
+
+       if (copy_from_user(&range, argp, sizeof(range))) {
+               status = -EFAULT;
+               goto out_free;
+       }
+
+       if (range.me_start > i_size_read(inode)) {
+               status = -EINVAL;
+               goto out_free;
+       }
+
+       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_copy;
+       }
+
+       status = ocfs2_move_extents(context);
+       if (status)
+               mlog_errno(status);
+out_copy:
+       /*
+        * 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 (copy_to_user(argp, &range, sizeof(range)))
+               status = -EFAULT;
+
+out_free:
+       kfree(context);
+out_drop:
+       mnt_drop_write_file(filp);
+
+       return status;
+}