Merge pull request #2203 from dscho/fix-racy-fsmonitor-gfw

Fix racy fsmonitor

The `t7519-status-fsmonitor.sh` tests became a *lot* more flaky with the
recent fsmonitor fix (`js/fsmonitor-refresh-after-discarding-index`).
That fix, however, did not introduce the flakiness, but it just made it
much more likely to be hit. And it seemed to be hit *only* on Windows.

The reason, though, is that the fsmonitor feature failed to mark the
in-memory index as changed, i.e. in need of writing, and it was the
`has_racy_timestamp()` test that hid this bug in most cases (although a
lot less on Windows, where the files' mtimes are actually a lot more
accurate than on Linux).

This fixes https://github.com/gitgitgadget/git/issues/197

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

apply.c

@@ -4320,7 +4320,7 @@ static int add_index_file(struct apply_state *state,
 						     "created file '%s'"),
 						   path);
 			}
-			fill_stat_cache_info(ce, &st);
+			fill_stat_cache_info(state->repo->index, ce, &st);
 		}
 		if (write_object_file(buf, size, blob_type, &ce->oid) < 0) {
 			discard_cache_entry(ce);

builtin/update-index.c

@@ -280,7 +280,7 @@ static int add_one_path(const struct cache_entry *old, const char *path, int len
 	memcpy(ce->name, path, len);
 	ce->ce_flags = create_ce_flags(0);
 	ce->ce_namelen = len;
-	fill_stat_cache_info(ce, st);
+	fill_stat_cache_info(&the_index, ce, st);
 	ce->ce_mode = ce_mode_from_stat(old, st->st_mode);
 
 	if (index_path(&the_index, &ce->oid, path, st,

cache.h

@@ -826,7 +826,7 @@ int match_stat_data(const struct stat_data *sd, struct stat *st);
 int match_stat_data_racy(const struct index_state *istate,
 			 const struct stat_data *sd, struct stat *st);
 
-void fill_stat_cache_info(struct cache_entry *ce, struct stat *st);
+void fill_stat_cache_info(struct index_state *istate, struct cache_entry *ce, struct stat *st);
 
 #define REFRESH_REALLY		0x0001	/* ignore_valid */
 #define REFRESH_UNMERGED	0x0002	/* allow unmerged */

diff-lib.c

@@ -232,7 +232,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 
 		if (!changed && !dirty_submodule) {
 			ce_mark_uptodate(ce);
-			mark_fsmonitor_valid(ce);
+			mark_fsmonitor_valid(istate, ce);
 			if (!revs->diffopt.flags.find_copies_harder)
 				continue;
 		}

entry.c

@@ -373,7 +373,7 @@ finish:
 			if (lstat(ce->name, &st) < 0)
 				return error_errno("unable to stat just-written file %s",
 						   ce->name);
-		fill_stat_cache_info(ce, &st);
+		fill_stat_cache_info(state->istate, ce, &st);
 		ce->ce_flags |= CE_UPDATE_IN_BASE;
 		mark_fsmonitor_invalid(state->istate, ce);
 		state->istate->cache_changed |= CE_ENTRY_CHANGED;

fsmonitor.h

@@ -49,9 +49,10 @@ void refresh_fsmonitor(struct index_state *istate);
  * called any time the cache entry has been updated to reflect the
  * current state of the file on disk.
  */
-static inline void mark_fsmonitor_valid(struct cache_entry *ce)
+static inline void mark_fsmonitor_valid(struct index_state *istate, struct cache_entry *ce)
 {
-	if (core_fsmonitor) {
+	if (core_fsmonitor && !(ce->ce_flags & CE_FSMONITOR_VALID)) {
+		istate->cache_changed = 1;
 		ce->ce_flags |= CE_FSMONITOR_VALID;
 		trace_printf_key(&trace_fsmonitor, "mark_fsmonitor_clean '%s'", ce->name);
 	}

preload-index.c

@@ -78,7 +78,7 @@ static void *preload_thread(void *_data)
 		if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))
 			continue;
 		ce_mark_uptodate(ce);
-		mark_fsmonitor_valid(ce);
+		mark_fsmonitor_valid(index, ce);
 	} while (--nr > 0);
 	if (p->progress) {
 		struct progress_data *pd = p->progress;

read-cache.c

@@ -195,7 +195,7 @@ int match_stat_data(const struct stat_data *sd, struct stat *st)
  * cache, ie the parts that aren't tracked by GIT, and only used
  * to validate the cache.
  */
-void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
+void fill_stat_cache_info(struct index_state *istate, struct cache_entry *ce, struct stat *st)
 {
 	fill_stat_data(&ce->ce_stat_data, st);
 
@@ -204,7 +204,7 @@ void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 
 	if (S_ISREG(st->st_mode)) {
 		ce_mark_uptodate(ce);
-		mark_fsmonitor_valid(ce);
+		mark_fsmonitor_valid(istate, ce);
 	}
 }
 
@@ -728,7 +728,7 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 	memcpy(ce->name, path, namelen);
 	ce->ce_namelen = namelen;
 	if (!intent_only)
-		fill_stat_cache_info(ce, st);
+		fill_stat_cache_info(istate, ce, st);
 	else
 		ce->ce_flags |= CE_INTENT_TO_ADD;
 
@@ -1432,7 +1432,7 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 			 */
 			if (!S_ISGITLINK(ce->ce_mode)) {
 				ce_mark_uptodate(ce);
-				mark_fsmonitor_valid(ce);
+				mark_fsmonitor_valid(istate, ce);
 			}
 			return ce;
 		}
@@ -1447,7 +1447,7 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 	updated = make_empty_cache_entry(istate, ce_namelen(ce));
 	copy_cache_entry(updated, ce);
 	memcpy(updated->name, ce->name, ce->ce_namelen + 1);
-	fill_stat_cache_info(updated, &st);
+	fill_stat_cache_info(istate, updated, &st);
 	/*
 	 * If ignore_valid is not set, we should leave CE_VALID bit
 	 * alone.  Otherwise, paths marked with --no-assume-unchanged