[RFCv1 59/72] e2fsck: update mmp block in one thread

["Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx>]

From: Wang Shilong <wshilong@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
 e2fsck/e2fsck.h |  1 +
 e2fsck/pass1.c  | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index 01bd9d01..2dd7ba27 100644
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -488,6 +488,7 @@ struct e2fsck_struct {
 
 #ifdef HAVE_PTHREAD
 	__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 93cff80e..ed4275c3 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1509,7 +1509,8 @@ 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;
+	e2fsck_t global_ctx = ctx->global_ctx ? ctx->global_ctx : ctx;
 
 	init_resource_track(&rtrack, ctx->fs->io);
 	clear_problem_context(&pctx);
@@ -1672,8 +1673,30 @@ 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	HAVE_PTHREAD
+		if (!global_ctx->mmp_update_thread) {
+			e2fsck_pass1_block_map_w_lock(ctx);
+			if (!global_ctx->mmp_update_thread) {
+				global_ctx->mmp_update_thread =
+					ctx->thread_info.et_thread_index + 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 (global_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);
 		}
@@ -2437,6 +2460,13 @@ endit:
 		print_resource_track(ctx, _("Pass 1"), &rtrack, ctx->fs->io);
 	else
 		ctx->invalid_bitmaps++;
+#ifdef	HAVE_PTHREAD
+	/* reset update_thread after this thread exit */
+	e2fsck_pass1_block_map_w_lock(ctx);
+	if (check_mmp)
+		global_ctx->mmp_update_thread = 0;
+	e2fsck_pass1_block_map_w_unlock(ctx);
+#endif
 }
 
 #ifdef HAVE_PTHREAD
-- 
2.37.3