ocfs2: Add support of decrementing refcount for delete.

    Given a physical cpos and length, decrement the refcount
in the tree. If the refcount for any portion of the extent goes
to zero, that portion is queued for freeing.

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

1 files changed, 254 insertions, 2 deletions

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index ee0422ce72c4..2c7974cccaf8 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -1071,6 +1071,10 @@ static void ocfs2_refcount_rec_merge(struct ocfs2_refcount_block *rb,
                 ocfs2_rotate_refcount_rec_left(rb, index);
 }
 
+/*
+ * Change the refcount indexed by "index" in ref_bh.
+ * If refcount reaches 0, remove it.
+ */
 static int ocfs2_change_refcount_rec(handle_t *handle,
                                      struct ocfs2_caching_info *ci,
                                      struct buffer_head *ref_leaf_bh,
@@ -1079,7 +1083,8 @@ static int ocfs2_change_refcount_rec(handle_t *handle,
         int ret;
         struct ocfs2_refcount_block *rb =
                         (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
-        struct ocfs2_refcount_rec *rec = &rb->rf_records.rl_recs[index];
+        struct ocfs2_refcount_list *rl = &rb->rf_records;
+        struct ocfs2_refcount_rec *rec = &rl->rl_recs[index];
 
         ret = ocfs2_journal_access_rb(handle, ci, ref_leaf_bh,
                                       OCFS2_JOURNAL_ACCESS_WRITE);
@@ -1092,7 +1097,18 @@ static int ocfs2_change_refcount_rec(handle_t *handle,
              le32_to_cpu(rec->r_refcount), change);
         le32_add_cpu(&rec->r_refcount, change);
 
-        ocfs2_refcount_rec_merge(rb, index);
+        if (!rec->r_refcount) {
+                if (index != le16_to_cpu(rl->rl_used) - 1) {
+                        memmove(rec, rec + 1,
+                                (le16_to_cpu(rl->rl_used) - index - 1) *
+                                sizeof(struct ocfs2_refcount_rec));
+                        memset(&rl->rl_recs[le16_to_cpu(rl->rl_used) - 1],
+                               0, sizeof(struct ocfs2_refcount_rec));
+                }
+
+                le16_add_cpu(&rl->rl_used, -1);
+        } else
+                ocfs2_refcount_rec_merge(rb, index);
 
         ret = ocfs2_journal_dirty(handle, ref_leaf_bh);
         if (ret)
@@ -1901,3 +1917,239 @@ out:
         brelse(ref_leaf_bh);
         return ret;
 }
+
+static int ocfs2_remove_refcount_extent(handle_t *handle,
+                                struct ocfs2_caching_info *ci,
+                                struct buffer_head *ref_root_bh,
+                                struct buffer_head *ref_leaf_bh,
+                                struct ocfs2_alloc_context *meta_ac,
+                                struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+        int ret;
+        struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
+        struct ocfs2_refcount_block *rb =
+                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
+        struct ocfs2_extent_tree et;
+
+        BUG_ON(rb->rf_records.rl_used);
+
+        ocfs2_init_refcount_extent_tree(&et, ci, ref_root_bh);
+        ret = ocfs2_remove_extent(handle, &et, le32_to_cpu(rb->rf_cpos),
+                                  1, meta_ac, dealloc);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ocfs2_remove_from_cache(ci, ref_leaf_bh);
+
+        /*
+         * add the freed block to the dealloc so that it will be freed
+         * when we run dealloc.
+         */
+        ret = ocfs2_cache_block_dealloc(dealloc, EXTENT_ALLOC_SYSTEM_INODE,
+                                        le16_to_cpu(rb->rf_suballoc_slot),
+                                        le64_to_cpu(rb->rf_blkno),
+                                        le16_to_cpu(rb->rf_suballoc_bit));
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_journal_access_rb(handle, ci, ref_root_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        rb = (struct ocfs2_refcount_block *)ref_root_bh->b_data;
+
+        le32_add_cpu(&rb->rf_clusters, -1);
+
+        /*
+         * check whether we need to restore the root refcount block if
+         * there is no leaf extent block at atll.
+         */
+        if (!rb->rf_list.l_next_free_rec) {
+                BUG_ON(rb->rf_clusters);
+
+                mlog(0, "reset refcount tree root %llu to be a record block.\n",
+                     (unsigned long long)ref_root_bh->b_blocknr);
+
+                rb->rf_flags = 0;
+                rb->rf_parent = 0;
+                rb->rf_cpos = 0;
+                memset(&rb->rf_records, 0, sb->s_blocksize -
+                       offsetof(struct ocfs2_refcount_block, rf_records));
+                rb->rf_records.rl_count =
+                                cpu_to_le16(ocfs2_refcount_recs_per_rb(sb));
+        }
+
+        ocfs2_journal_dirty(handle, ref_root_bh);
+
+out:
+        return ret;
+}
+
+static int ocfs2_decrease_refcount_rec(handle_t *handle,
+                                struct ocfs2_caching_info *ci,
+                                struct buffer_head *ref_root_bh,
+                                struct buffer_head *ref_leaf_bh,
+                                int index, u64 cpos, unsigned int len,
+                                struct ocfs2_alloc_context *meta_ac,
+                                struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+        int ret;
+        struct ocfs2_refcount_block *rb =
+                        (struct ocfs2_refcount_block *)ref_leaf_bh->b_data;
+        struct ocfs2_refcount_rec *rec = &rb->rf_records.rl_recs[index];
+
+        BUG_ON(cpos < le64_to_cpu(rec->r_cpos));
+        BUG_ON(cpos + len >
+               le64_to_cpu(rec->r_cpos) + le32_to_cpu(rec->r_clusters));
+
+        if (cpos == le64_to_cpu(rec->r_cpos) &&
+            len == le32_to_cpu(rec->r_clusters))
+                ret = ocfs2_change_refcount_rec(handle, ci,
+                                                ref_leaf_bh, index, -1);
+        else {
+                struct ocfs2_refcount_rec split = *rec;
+                split.r_cpos = cpu_to_le64(cpos);
+                split.r_clusters = cpu_to_le32(len);
+
+                le32_add_cpu(&split.r_refcount, -1);
+
+                mlog(0, "split refcount rec, start %llu, "
+                     "len %u, count %u, original start %llu, len %u\n",
+                     (unsigned long long)le64_to_cpu(split.r_cpos),
+                     len, le32_to_cpu(split.r_refcount),
+                     (unsigned long long)le64_to_cpu(rec->r_cpos),
+                     le32_to_cpu(rec->r_clusters));
+                ret = ocfs2_split_refcount_rec(handle, ci,
+                                               ref_root_bh, ref_leaf_bh,
+                                               &split, index,
+                                               meta_ac, dealloc);
+        }
+
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /* Remove the leaf refcount block if it contains no refcount record. */
+        if (!rb->rf_records.rl_used && ref_leaf_bh != ref_root_bh) {
+                ret = ocfs2_remove_refcount_extent(handle, ci, ref_root_bh,
+                                                   ref_leaf_bh, meta_ac,
+                                                   dealloc);
+                if (ret)
+                        mlog_errno(ret);
+        }
+
+out:
+        return ret;
+}
+
+static int __ocfs2_decrease_refcount(handle_t *handle,
+                                     struct ocfs2_caching_info *ci,
+                                     struct buffer_head *ref_root_bh,
+                                     u64 cpos, u32 len,
+                                     struct ocfs2_alloc_context *meta_ac,
+                                     struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+        int ret = 0, index = 0;
+        struct ocfs2_refcount_rec rec;
+        unsigned int r_count = 0, r_len;
+        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",
+             (unsigned long long)ocfs2_metadata_cache_owner(ci),
+             (unsigned long long)cpos, len);
+
+        while (len) {
+                ret = ocfs2_get_refcount_rec(ci, ref_root_bh,
+                                             cpos, len, &rec, &index,
+                                             &ref_leaf_bh);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                r_count = le32_to_cpu(rec.r_refcount);
+                BUG_ON(r_count == 0);
+
+                r_len = min((u64)(cpos + len), le64_to_cpu(rec.r_cpos) +
+                              le32_to_cpu(rec.r_clusters)) - cpos;
+
+                ret = ocfs2_decrease_refcount_rec(handle, ci, ref_root_bh,
+                                                  ref_leaf_bh, index,
+                                                  cpos, r_len,
+                                                  meta_ac, dealloc);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                if (le32_to_cpu(rec.r_refcount) == 1) {
+                        ret = ocfs2_cache_cluster_dealloc(dealloc,
+                                          ocfs2_clusters_to_blocks(sb, cpos),
+                                                          r_len);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+                }
+
+                cpos += r_len;
+                len -= r_len;
+                brelse(ref_leaf_bh);
+                ref_leaf_bh = NULL;
+        }
+
+out:
+        brelse(ref_leaf_bh);
+        return ret;
+}
+
+/* Caller must hold refcount tree lock. */
+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)
+{
+        int ret;
+        u64 ref_blkno;
+        struct ocfs2_inode_info *oi = OCFS2_I(inode);
+        struct buffer_head *ref_root_bh = NULL;
+        struct ocfs2_refcount_tree *tree;
+
+        BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+
+        ret = ocfs2_get_refcount_block(inode, &ref_blkno);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb), ref_blkno, &tree);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_read_refcount_block(&tree->rf_ci, tree->rf_blkno,
+                                        &ref_root_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = __ocfs2_decrease_refcount(handle, &tree->rf_ci, ref_root_bh,
+                                        cpos, len, meta_ac, dealloc);
+        if (ret)
+                mlog_errno(ret);
+out:
+        brelse(ref_root_bh);
+        return ret;
+}