1 files changed, 47 insertions, 2 deletions

diff --git a/cache-tree.c b/cache-tree.c
index add1f07713..90919f9e34 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -6,6 +6,7 @@
 #include "object-store.h"
 #include "replace-object.h"
 #include "promisor-remote.h"
+#include "sparse-index.h"
 
 #ifndef DEBUG_CACHE_TREE
 #define DEBUG_CACHE_TREE 0
@@ -236,6 +237,11 @@ int cache_tree_fully_valid(struct cache_tree *it)
 	return 1;
 }
 
+static int must_check_existence(const struct cache_entry *ce)
+{
+	return !(has_promisor_remote() && ce_skip_worktree(ce));
+}
+
 static int update_one(struct cache_tree *it,
 		      struct cache_entry **cache,
 		      int entries,
@@ -255,6 +261,24 @@ static int update_one(struct cache_tree *it,
 
 	*skip_count = 0;
 
+	/*
+	 * If the first entry of this region is a sparse directory
+	 * entry corresponding exactly to 'base', then this cache_tree
+	 * struct is a "leaf" in the data structure, pointing to the
+	 * tree OID specified in the entry.
+	 */
+	if (entries > 0) {
+		const struct cache_entry *ce = cache[0];
+
+		if (S_ISSPARSEDIR(ce->ce_mode) &&
+		    ce->ce_namelen == baselen &&
+		    !strncmp(ce->name, base, baselen)) {
+			it->entry_count = 1;
+			oidcpy(&it->oid, &ce->oid);
+			return 1;
+		}
+	}
+
 	if (0 <= it->entry_count && has_object_file(&it->oid))
 		return it->entry_count;
 
@@ -359,8 +383,7 @@ static int update_one(struct cache_tree *it,
 		}
 
 		ce_missing_ok = mode == S_IFGITLINK || missing_ok ||
-			(has_promisor_remote() &&
-			 ce_skip_worktree(ce));
+			!must_check_existence(ce);
 		if (is_null_oid(oid) ||
 		    (!ce_missing_ok && !has_object_file(oid))) {
 			strbuf_release(&buffer);
@@ -445,6 +468,9 @@ int cache_tree_update(struct index_state *istate, int flags)
 	if (!istate->cache_tree)
 		istate->cache_tree = cache_tree();
 
+	if (!(flags & WRITE_TREE_MISSING_OK) && has_promisor_remote())
+		prefetch_cache_entries(istate, must_check_existence);
+
 	trace_performance_enter();
 	trace2_region_enter("cache_tree", "update", the_repository);
 	i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
@@ -787,6 +813,19 @@ int cache_tree_matches_traversal(struct cache_tree *root,
 	return 0;
 }
 
+static void verify_one_sparse(struct repository *r,
+			      struct index_state *istate,
+			      struct cache_tree *it,
+			      struct strbuf *path,
+			      int pos)
+{
+	struct cache_entry *ce = istate->cache[pos];
+
+	if (!S_ISSPARSEDIR(ce->ce_mode))
+		BUG("directory '%s' is present in index, but not sparse",
+		    path->buf);
+}
+
 static void verify_one(struct repository *r,
 		       struct index_state *istate,
 		       struct cache_tree *it,
@@ -809,6 +848,12 @@ static void verify_one(struct repository *r,
 
 	if (path->len) {
 		pos = index_name_pos(istate, path->buf, path->len);
+
+		if (pos >= 0) {
+			verify_one_sparse(r, istate, it, path, pos);
+			return;
+		}
+
 		pos = -pos - 1;
 	} else {
 		pos = 0;