Ocfs2/move_extents: defrag a range of extent.

It's a relatively complete function to accomplish defragmentation for entire
or partial extent, one journal handle was kept during the operation, it was
logically doing one more thing than ocfs2_move_extent() acutally, yes, it's
claiming the new clusters itself;-)

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>

1 files changed, 136 insertions, 0 deletions

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index d1bd5a347e9c..78db10d4c7f1 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -215,3 +215,139 @@ out:
 
         return ret;
 }
+
+/*
+ * Using one journal handle to guarantee the data consistency in case
+ * crash happens anywhere.
+ */
+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;
+        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;
+        }
+
+        /*
+         * we're not quite patient here to make multiple attempts for claiming
+         * enough clusters, failure to claim clusters per-requested is not a
+         * disaster though, it can only mean partial range of defragmentation
+         * or extent movements gets gone, users anyway is able to have another
+         * try as they wish anytime, since they're going to be returned a
+         * '-ENOSPC' and completed length of this movement.
+         */
+        if (new_len != len) {
+                mlog(0, "len_claimed: %u, len: %u\n", new_len, len);
+                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, len, phys_cpos,
+                                  new_phys_cpos, ext_flags);
+        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);
+
+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;
+}