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Date:   Wed, 18 Nov 2020 07:39:33 -0800
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Subject: [RFC PATCH v3 47/61] e2fsck: update mmp block in one thread
From:   Saranya Muruganandam <saranyamohan@google.com>
To:     linux-ext4@vger.kernel.org, tytso@mit.edu
Cc:     adilger.kernel@dilger.ca, Wang Shilong <wshilong@ddn.com>,
        Saranya Muruganandam <saranyamohan@google.com>
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From: Wang Shilong <wshilong@ddn.com>

For multiple threads, different threads will try to
update mmp block at the same time, only allow one
thread to update it.

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Signed-off-by: Saranya Muruganandam <saranyamohan@google.com>
---
 e2fsck/e2fsck.h |  1 +
 e2fsck/pass1.c  | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index a66772c1..1469c3e1 100644
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -451,6 +451,7 @@ struct e2fsck_struct {
 	char *undo_file;
 #ifdef CONFIG_PFSCK
 	__u32			 fs_num_threads;
+	__u32			 mmp_update_thread;
 	int			 fs_need_locking;
 	/* serialize fix operation for multiple threads */
 	pthread_rwlock_t	 fs_fix_rwlock;
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 60f70111..e98cda9f 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1497,7 +1497,7 @@ void e2fsck_pass1_run(e2fsck_t ctx)
 	dgrp_t		ra_group = 0;
 	struct ea_quota	ea_ibody_quota;
 	struct process_inode_block *inodes_to_process;
-	int		process_inode_count;
+	int		process_inode_count, check_mmp;
 
 	init_resource_track(&rtrack, ctx->fs->io);
 	clear_problem_context(&pctx);
@@ -1646,8 +1646,33 @@ void e2fsck_pass1_run(e2fsck_t ctx)
 #endif
 
 	while (1) {
+		check_mmp = 0;
 		e2fsck_pass1_check_lock(ctx);
-		if (ino % (fs->super->s_inodes_per_group * 4) == 1) {
+#ifdef	CONFIG_PFSCK
+		if (!ctx->mmp_update_thread) {
+			e2fsck_pass1_block_map_w_lock(ctx);
+			if (!ctx->mmp_update_thread) {
+				if (ctx->global_ctx)
+					ctx->mmp_update_thread =
+						ctx->thread_info.et_thread_index + 1;
+				else
+					ctx->mmp_update_thread = 1;
+				check_mmp = 1;
+			}
+			e2fsck_pass1_block_map_w_unlock(ctx);
+		}
+
+		/* only one active thread could update mmp block. */
+		e2fsck_pass1_block_map_r_lock(ctx);
+		if (!ctx->global_ctx || ctx->mmp_update_thread ==
+			(ctx->thread_info.et_thread_index + 1))
+			check_mmp = 1;
+		e2fsck_pass1_block_map_r_unlock(ctx);
+#else
+		check_mmp = 1;
+#endif
+
+		if (check_mmp && (ino % (fs->super->s_inodes_per_group * 4) == 1)) {
 			if (e2fsck_mmp_update(fs))
 				fatal_error(ctx, 0);
 		}
@@ -2365,6 +2390,13 @@ endit:
 		print_resource_track(ctx, _("Pass 1"), &rtrack, ctx->fs->io);
 	else
 		ctx->invalid_bitmaps++;
+#ifdef	CONFIG_PFSCK
+	/* reset update_thread after this thread exit */
+	e2fsck_pass1_block_map_w_lock(ctx);
+	if (ctx->mmp_update_thread)
+		ctx->mmp_update_thread = 0;
+	e2fsck_pass1_block_map_w_unlock(ctx);
+#endif
 }
 
 #ifdef CONFIG_PFSCK
-- 
2.29.2.299.gdc1121823c-goog