ocfs2: Decrement refcount when truncating refcounted extents.

Add 'Decrement refcount for delete' in to the normal truncate
process. So for a refcounted extent record, call refcount rec
decrementation instead of cluster free.

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

1 files changed, 212 insertions, 0 deletions

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index f7d19f4db897..e72dbdd3b6e8 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2192,3 +2192,215 @@ static int ocfs2_mark_extent_refcounted(struct inode *inode,
 out:
         return ret;
 }
+
+/*
+ * Given some contiguous physical clusters, calculate what we need
+ * for modifying their refcount.
+ */
+static int ocfs2_calc_refcount_meta_credits(struct super_block *sb,
+                                            struct ocfs2_caching_info *ci,
+                                            struct buffer_head *ref_root_bh,
+                                            u64 start_cpos,
+                                            u32 clusters,
+                                            int *meta_add,
+                                            int *credits)
+{
+        int ret = 0, index, ref_blocks = 0, recs_add = 0;
+        u64 cpos = start_cpos;
+        struct ocfs2_refcount_block *rb;
+        struct ocfs2_refcount_rec rec;
+        struct buffer_head *ref_leaf_bh = NULL, *prev_bh = NULL;
+        u32 len;
+
+        mlog(0, "start_cpos %llu, clusters %u\n",
+             (unsigned long long)start_cpos, clusters);
+        while (clusters) {
+                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
+                                             cpos, clusters, &rec,
+                                             &index, &ref_leaf_bh);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                if (ref_leaf_bh != prev_bh) {
+                        /*
+                         * Now we encounter a new leaf block, so calculate
+                         * whether we need to extend the old leaf.
+                         */
+                        if (prev_bh) {
+                                rb = (struct ocfs2_refcount_block *)
+                                                        prev_bh->b_data;
+
+                                if (le64_to_cpu(rb->rf_records.rl_used) +
+                                    recs_add >
+                                    le16_to_cpu(rb->rf_records.rl_count))
+                                        ref_blocks++;
+                        }
+
+                        recs_add = 0;
+                        *credits += 1;
+                        brelse(prev_bh);
+                        prev_bh = ref_leaf_bh;
+                        get_bh(prev_bh);
+                }
+
+                rb = (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
+
+                mlog(0, "recs_add %d,cpos %llu, clusters %u, rec->r_cpos %llu,"
+                     "rec->r_clusters %u, rec->r_refcount %u, index %d\n",
+                     recs_add, (unsigned long long)cpos, clusters,
+                     (unsigned long long)le64_to_cpu(rec.r_cpos),
+                     le32_to_cpu(rec.r_clusters),
+                     le32_to_cpu(rec.r_refcount), index);
+
+                len = min((u64)cpos + clusters, le64_to_cpu(rec.r_cpos) +
+                          le32_to_cpu(rec.r_clusters)) - cpos;
+                /*
+                 * If the refcount rec already exist, cool. We just need
+                 * to check whether there is a split. Otherwise we just need
+                 * to increase the refcount.
+                 * If we will insert one, increases recs_add.
+                 *
+                 * We record all the records which will be inserted to the
+                 * same refcount block, so that we can tell exactly whether
+                 * we need a new refcount block or not.
+                 */
+                if (rec.r_refcount) {
+                        /* Check whether we need a split at the beginning. */
+                        if (cpos == start_cpos &&
+                            cpos != le64_to_cpu(rec.r_cpos))
+                                recs_add++;
+
+                        /* Check whether we need a split in the end. */
+                        if (cpos + clusters < le64_to_cpu(rec.r_cpos) +
+                            le32_to_cpu(rec.r_clusters))
+                                recs_add++;
+                } else
+                        recs_add++;
+
+                brelse(ref_leaf_bh);
+                ref_leaf_bh = NULL;
+                clusters -= len;
+                cpos += len;
+        }
+
+        if (prev_bh) {
+                rb = (struct ocfs2_refcount_block *)prev_bh->b_data;
+
+                if (le64_to_cpu(rb->rf_records.rl_used) + recs_add >
+                    le16_to_cpu(rb->rf_records.rl_count))
+                        ref_blocks++;
+
+                *credits += 1;
+        }
+
+        if (!ref_blocks)
+                goto out;
+
+        mlog(0, "we need ref_blocks %d\n", ref_blocks);
+        *meta_add += ref_blocks;
+        *credits += ref_blocks;
+
+        /*
+         * So we may need ref_blocks to insert into the tree.
+         * That also means we need to change the b-tree and add that number
+         * of records since we never merge them.
+         * We need one more block for expansion since the new created leaf
+         * block is also full and needs split.
+         */
+        rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
+        if (le32_to_cpu(rb->rf_flags) & OCFS2_REFCOUNT_TREE_FL) {
+                struct ocfs2_extent_tree et;
+
+                ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
+                *meta_add += ocfs2_extend_meta_needed(et.et_root_el);
+                *credits += ocfs2_calc_extend_credits(sb,
+                                                      et.et_root_el,
+                                                      ref_blocks);
+        } else {
+                *credits += OCFS2_EXPAND_REFCOUNT_TREE_CREDITS;
+                *meta_add += 1;
+        }
+
+out:
+        brelse(ref_leaf_bh);
+        brelse(prev_bh);
+        return ret;
+}
+
+/*
+ * For refcount tree, we will decrease some contiguous clusters
+ * refcount count, so just go through it to see how many blocks
+ * we gonna touch and whether we need to create new blocks.
+ *
+ * Normally the refcount blocks store these refcount should be
+ * continguous also, so that we can get the number easily.
+ * As for meta_ac, we will at most add split 2 refcount record and
+ * 2 more refcount block, so just check it in a rough way.
+ *
+ * Caller must hold refcount tree lock.
+ */
+int ocfs2_prepare_refcount_change_for_del(struct inode *inode,
+                                          struct buffer_head *di_bh,
+                                          u64 phys_blkno,
+                                          u32 clusters,
+                                          int *credits,
+                                          struct ocfs2_alloc_context **meta_ac)
+{
+        int ret, ref_blocks = 0;
+        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
+        struct ocfs2_inode_info *oi = OCFS2_I(inode);
+        struct buffer_head *ref_root_bh = NULL;
+        struct ocfs2_refcount_tree *tree;
+        u64 start_cpos = ocfs2_blocks_to_clusters(inode->i_sb, phys_blkno);
+
+        if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb))) {
+                ocfs2_error(inode->i_sb, "Inode %lu want to use refcount "
+                            "tree, but the feature bit is not set in the "
+                            "super block.", inode->i_ino);
+                ret = -EROFS;
+                goto out;
+        }
+
+        BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+
+        ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb),
+                                      le64_to_cpu(di->i_refcount_loc), &tree);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_read_refcount_block(&tree->rf_ci,
+                                        le64_to_cpu(di->i_refcount_loc),
+                                        &ref_root_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_calc_refcount_meta_credits(inode->i_sb,
+                                               &tree->rf_ci,
+                                               ref_root_bh,
+                                               start_cpos, clusters,
+                                               &ref_blocks, credits);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        mlog(0, "reserve new metadata %d, credits = %d\n",
+             ref_blocks, *credits);
+
+        if (ref_blocks) {
+                ret = ocfs2_reserve_new_metadata_blocks(OCFS2_SB(inode->i_sb),
+                                                        ref_blocks, meta_ac);
+                if (ret)
+                        mlog_errno(ret);
+        }
+
+out:
+        brelse(ref_root_bh);
+        return ret;
+}