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From:   Lukas Czerner <lczerner@redhat.com>
To:     tytso@mit.edu
Cc:     linux-ext4@vger.kernel.org, Lukas Herbolt <lukas@herbolt.com>
Subject: [PATCH] ext4: print file system UUID on mount, remount and unmount
Date:   Tue,  8 Nov 2022 15:50:42 +0100
Message-Id: <20221108145042.85770-1-lczerner@redhat.com>
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The device names are not necessarily consistent across reboots which can
make it more difficult to identify the right file system when tracking
down issues using system logs.

Print file system UUID string on every mount, remount and unmount to
make this task easier.

This is similar to the functionality recently propsed for XFS.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Lukas Herbolt <lukas@herbolt.com>
---
 fs/ext4/super.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7cdd2138c897..4028bfc8206c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1206,7 +1206,8 @@ static void ext4_put_super(struct super_block *sb)
 	ext4_unregister_sysfs(sb);
 
 	if (___ratelimit(&ext4_mount_msg_ratelimit, "EXT4-fs unmount"))
-		ext4_msg(sb, KERN_INFO, "unmounting filesystem.");
+		ext4_msg(sb, KERN_INFO, "unmounting filesystem %pU.",
+			 &sb->s_uuid);
 
 	ext4_unregister_li_request(sb);
 	ext4_quota_off_umount(sb);
@@ -5655,8 +5656,9 @@ static int ext4_fill_super(struct super_block *sb, struct fs_context *fc)
 		descr = "out journal";
 
 	if (___ratelimit(&ext4_mount_msg_ratelimit, "EXT4-fs mount"))
-		ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. "
-			 "Quota mode: %s.", descr, ext4_quota_mode(sb));
+		ext4_msg(sb, KERN_INFO, "mounted filesystem %pU with%s. "
+			 "Quota mode: %s.", &sb->s_uuid, descr,
+			 ext4_quota_mode(sb));
 
 	/* Update the s_overhead_clusters if necessary */
 	ext4_update_overhead(sb, false);
@@ -6611,8 +6613,8 @@ static int ext4_reconfigure(struct fs_context *fc)
 	if (ret < 0)
 		return ret;
 
-	ext4_msg(sb, KERN_INFO, "re-mounted. Quota mode: %s.",
-		 ext4_quota_mode(sb));
+	ext4_msg(sb, KERN_INFO, "re-mounted %pU. Quota mode: %s.",
+		 &sb->s_uuid, ext4_quota_mode(sb));
 
 	return 0;
 }
-- 
2.38.1