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From:   "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
To:     Theodore Ts'o <tytso@mit.edu>
Cc:     linux-ext4@vger.kernel.org,
        Harshad Shirwadkar <harshadshirwadkar@gmail.com>,
        Wang Shilong <wshilong@ddn.com>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Li Xi <lixi@ddn.com>, Ritesh Harjani <ritesh.list@gmail.com>
Subject: [RFCv1 37/72] e2fsck: add debug codes for multiple threads
Date:   Mon,  7 Nov 2022 17:51:25 +0530
Message-Id: <6034e7dc1304ad2eea9ffabff96cb1604336d3e9.1667822611.git.ritesh.list@gmail.com>
In-Reply-To: <cover.1667822611.git.ritesh.list@gmail.com>
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From: Li Xi <lixi@ddn.com>

These debug codes are added to run the multiple pass1 check
thread one by one in order. If all the codes are correct,
fsck of multiple threads should have exactly the same outcome
with single thread.

Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 e2fsck/e2fsck.h | 16 ++++++++++++++++
 e2fsck/pass1.c  | 29 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index 2ee37f78..9b0f5067 100644
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -489,6 +489,18 @@ struct e2fsck_struct {
 };
 
 #ifdef HAVE_PTHREAD
+#ifdef DEBUG_THREADS
+/*
+ * Enabling DEBUG_THREADS would cause the parallel
+ * fsck threads run sequentially.
+ */
+struct e2fsck_thread_debug {
+	pthread_mutex_t	etd_mutex;
+	pthread_cond_t	etd_cond;
+	int		etd_finished_threads;
+};
+#endif
+
 struct e2fsck_thread_info {
 	/* ID returned by pthread_create() */
 	pthread_t		 eti_thread_id;
@@ -498,7 +510,11 @@ struct e2fsck_thread_info {
 	int			 eti_started;
 	/* Context used for this thread */
 	e2fsck_t		 eti_thread_ctx;
+#ifdef DEBUG_THREADS
+	struct e2fsck_thread_debug	*eti_debug;
+#endif
 };
+
 #endif
 
 /* Data structures to evaluate whether an extent tree needs rebuilding. */
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 18bf7efd..752dca03 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -2575,6 +2575,18 @@ static void *e2fsck_pass1_thread(void *arg)
 {
 	struct e2fsck_thread_info *info = arg;
 	e2fsck_t thread_ctx = info->eti_thread_ctx;
+#ifdef DEBUG_THREADS
+	struct e2fsck_thread_debug *thread_debug = info->eti_debug;
+#endif
+
+#ifdef DEBUG_THREADS
+	pthread_mutex_lock(&thread_debug->etd_mutex);
+	while (info->eti_thread_index > thread_debug->etd_finished_threads) {
+		pthread_cond_wait(&thread_debug->etd_cond,
+				  &thread_debug->etd_mutex);
+	}
+	pthread_mutex_unlock(&thread_debug->etd_mutex);
+#endif
 
 #ifdef HAVE_SETJMP_H
 	/*
@@ -2599,6 +2611,14 @@ out:
 			thread_ctx->thread_info.et_group_start,
 			thread_ctx->thread_info.et_group_end,
 			thread_ctx->thread_info.et_inode_number);
+
+#ifdef DEBUG_THREADS
+	pthread_mutex_lock(&thread_debug->etd_mutex);
+	thread_debug->etd_finished_threads++;
+	pthread_cond_broadcast(&thread_debug->etd_cond);
+	pthread_mutex_unlock(&thread_debug->etd_mutex);
+#endif
+
 	return NULL;
 }
 
@@ -2612,6 +2632,12 @@ static int e2fsck_pass1_threads_start(struct e2fsck_thread_info **pinfo,
 	struct e2fsck_thread_info *tmp_pinfo;
 	int i;
 	e2fsck_t thread_ctx;
+#ifdef DEBUG_THREADS
+	struct e2fsck_thread_debug thread_debug =
+		{PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0};
+
+	thread_debug.etd_finished_threads = 0;
+#endif
 
 	retval = pthread_attr_init(&attr);
 	if (retval) {
@@ -2632,6 +2658,9 @@ static int e2fsck_pass1_threads_start(struct e2fsck_thread_info **pinfo,
 	for (i = 0; i < num_threads; i++) {
 		tmp_pinfo = &infos[i];
 		tmp_pinfo->eti_thread_index = i;
+#ifdef DEBUG_THREADS
+		tmp_pinfo->eti_debug = &thread_debug;
+#endif
 		retval = e2fsck_pass1_thread_prepare(global_ctx, &thread_ctx,
 						     i, num_threads);
 		if (retval) {
-- 
2.37.3