[PATCH 2/2] fsmonitor: force a refresh after the index was discarded

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

With this change, the `index_state` struct becomes the new home for the
flag that says whether the fsmonitor hook has been run, i.e. it is now
per-index.

It also gets re-set when the index is discarded, fixing the bug where
fsmonitor-enabled Git would miss updates under certain circumstances.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 cache.h                     | 3 ++-
 fsmonitor.c                 | 5 ++---
 read-cache.c                | 1 +
 t/t7519-status-fsmonitor.sh | 2 +-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/cache.h b/cache.h
index abd518a9a2..8d07c29c2a 100644
--- a/cache.h
+++ b/cache.h
@@ -339,7 +339,8 @@ struct index_state {
 	struct cache_time timestamp;
 	unsigned name_hash_initialized : 1,
 		 initialized : 1,
-		 drop_cache_tree : 1;
+		 drop_cache_tree : 1,
+		 fsmonitor_has_run_once : 1;
 	struct hashmap name_hash;
 	struct hashmap dir_hash;
 	struct object_id oid;
diff --git a/fsmonitor.c b/fsmonitor.c
index 665bd2d425..1dee0aded1 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -129,7 +129,6 @@ static void fsmonitor_refresh_callback(struct index_state *istate, const char *n
 
 void refresh_fsmonitor(struct index_state *istate)
 {
-	static int has_run_once = 0;
 	struct strbuf query_result = STRBUF_INIT;
 	int query_success = 0;
 	size_t bol; /* beginning of line */
@@ -137,9 +136,9 @@ void refresh_fsmonitor(struct index_state *istate)
 	char *buf;
 	int i;
 
-	if (!core_fsmonitor || has_run_once)
+	if (!core_fsmonitor || istate->fsmonitor_has_run_once)
 		return;
-	has_run_once = 1;
+	istate->fsmonitor_has_run_once = 1;
 
 	trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
 	/*
diff --git a/read-cache.c b/read-cache.c
index 4dc6de1b55..0bf39e177a 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -2335,6 +2335,7 @@ int discard_index(struct index_state *istate)
 	free_name_hash(istate);
 	cache_tree_free(&(istate->cache_tree));
 	istate->initialized = 0;
+	istate->fsmonitor_has_run_once = 0;
 	FREE_AND_NULL(istate->cache);
 	istate->cache_alloc = 0;
 	discard_split_index(istate);
diff --git a/t/t7519-status-fsmonitor.sh b/t/t7519-status-fsmonitor.sh
index 918bc323ab..72b9ed3e45 100755
--- a/t/t7519-status-fsmonitor.sh
+++ b/t/t7519-status-fsmonitor.sh
@@ -346,7 +346,7 @@ test_expect_success UNTRACKED_CACHE 'ignore .git changes when invalidating UNTR'
 	test_cmp before after
 '
 
-test_expect_failure 'discard_index() also discards fsmonitor info' '
+test_expect_success 'discard_index() also discards fsmonitor info' '
 	test_when_finished \
 		"git config core.monitor .git/hooks/fsmonitor-test" &&
 	test_config core.fsmonitor "$TEST_DIRECTORY/t7519/fsmonitor-all" &&
-- 
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