ocfs2: CoW refcount tree improvement.

During CoW, if the old extent record is refcounted, we allocate
som new clusters and do CoW. Actually we can have some improvement
here. If the old extent has refcount=1, that means now it is only
used by this file. So we don't need to allocate new clusters, just
remove the refcounted flag and it is OK. We also have to remove
it from the refcount tree while not deleting it.

Signed-off-by: Tao Ma <tao.ma@oracle.com>

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index b8fc95d10630bd4a5597db4cc630c1a6bdce42c6..7c879fc7834f26241fcc0b593eb3089af4c3cbfb 100644 (file)
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -6974,7 +6974,7 @@ static int ocfs2_do_truncate(struct ocfs2_super *osb,
                                        ocfs2_blocks_to_clusters(osb->sb,
                                                                 delete_blk),
                                        clusters_to_del, meta_ac,
-                                       &tc->tc_dealloc);
+                                       &tc->tc_dealloc, 1);
                else
                        status = ocfs2_truncate_log_append(osb, handle,
                                                           delete_blk,

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 4e7df8b8fd4f7fbc9c907ed77334c41016d1b8eb..0a92436557e34cc13d309c1a44cd19061f0f8c21 100644 (file)
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2076,7 +2076,8 @@ static int __ocfs2_decrease_refcount(handle_t *handle,
                                     struct buffer_head *ref_root_bh,
                                     u64 cpos, u32 len,
                                     struct ocfs2_alloc_context *meta_ac,
-                                    struct ocfs2_cached_dealloc_ctxt *dealloc)
+                                    struct ocfs2_cached_dealloc_ctxt *dealloc,
+                                    int delete)
 {
        int ret = 0, index = 0;
        struct ocfs2_refcount_rec rec;
@@ -2084,9 +2085,10 @@ static int __ocfs2_decrease_refcount(handle_t *handle,
        struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
        struct buffer_head *ref_leaf_bh = NULL;
 
-       mlog(0, "Tree owner %llu, decrease refcount start %llu, len %u\n",
+       mlog(0, "Tree owner %llu, decrease refcount start %llu, "
+            "len %u, delete %u\n",
             (unsigned long long)ocfs2_metadata_cache_owner(ci),
-            (unsigned long long)cpos, len);
+            (unsigned long long)cpos, len, delete);
 
        while (len) {
                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
@@ -2099,6 +2101,8 @@ static int __ocfs2_decrease_refcount(handle_t *handle,
 
                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;
@@ -2112,7 +2116,7 @@ static int __ocfs2_decrease_refcount(handle_t *handle,
                        goto out;
                }
 
-               if (le32_to_cpu(rec.r_refcount) == 1) {
+               if (le32_to_cpu(rec.r_refcount) == 1 && delete) {
                        ret = ocfs2_cache_cluster_dealloc(dealloc,
                                          ocfs2_clusters_to_blocks(sb, cpos),
                                                          r_len);
@@ -2137,7 +2141,8 @@ out:
 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)
+                           struct ocfs2_cached_dealloc_ctxt *dealloc,
+                           int delete)
 {
        int ret;
        u64 ref_blkno;
@@ -2167,7 +2172,7 @@ int ocfs2_decrease_refcount(struct inode *inode,
        }
 
        ret = __ocfs2_decrease_refcount(handle, &tree->rf_ci, ref_root_bh,
-                                       cpos, len, meta_ac, dealloc);
+                                       cpos, len, meta_ac, dealloc, delete);
        if (ret)
                mlog_errno(ret);
 out:
@@ -2974,10 +2979,16 @@ static int ocfs2_make_clusters_writable(struct super_block *sb,
                                        u32 cpos, u32 p_cluster,
                                        u32 num_clusters, unsigned int e_flags)
 {
-       int ret, credits =  0;
+       int ret, delete, index, credits =  0;
        u32 new_bit, new_len;
+       unsigned int set_len;
        struct ocfs2_super *osb = OCFS2_SB(sb);
        handle_t *handle;
+       struct buffer_head *ref_leaf_bh = NULL;
+       struct ocfs2_refcount_rec rec;
+
+       mlog(0, "cpos %u, p_cluster %u, num_clusters %u, e_flags %u\n",
+            cpos, p_cluster, num_clusters, e_flags);
 
        ret = ocfs2_lock_refcount_allocators(sb, p_cluster, num_clusters,
                                             &context->di_et,
@@ -2998,35 +3009,75 @@ static int ocfs2_make_clusters_writable(struct super_block *sb,
        }
 
        while (num_clusters) {
-               ret = __ocfs2_claim_clusters(osb, handle, context->data_ac,
-                                            1, num_clusters,
-                                            &new_bit, &new_len);
+               ret = ocfs2_get_refcount_rec(context->ref_ci,
+                                            context->ref_root_bh,
+                                            p_cluster, num_clusters,
+                                            &rec, &index, &ref_leaf_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out_commit;
                }
 
-               ret = ocfs2_replace_clusters(handle, context,
-                                            cpos, p_cluster, new_bit,
-                                            new_len, e_flags);
+               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->di_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(osb, 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, context->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 += new_len;
-               p_cluster += new_len;
-               num_clusters -= new_len;
-       }
-
-       ret = __ocfs2_decrease_refcount(handle, context->ref_ci,
-                                       context->ref_root_bh,
-                                       p_cluster, num_clusters,
-                                       context->meta_ac,
-                                       &context->dealloc);
-       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;
        }
 
        /*
@@ -3049,6 +3100,7 @@ out:
                ocfs2_free_alloc_context(context->meta_ac);
                context->meta_ac = NULL;
        }
+       brelse(ref_leaf_bh);
 
        return ret;
 }

diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index 9960878134dfc3459606b23e89f4ccbf9a400215..a8c15b0b2307b7f2c7e88cdfd5e9d763259c8292 100644 (file)
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -44,7 +44,8 @@ void ocfs2_unlock_refcount_tree(struct ocfs2_super *osb,
 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);
+                           struct ocfs2_cached_dealloc_ctxt *dealloc,
+                           int delete);
 int ocfs2_prepare_refcount_change_for_del(struct inode *inode,
                                          struct buffer_head *di_bh,
                                          u64 phys_blkno,