[PATCH] ext4: fix incorrect options show of original mount_opt and extend mount_opt2

[Zhang Yi <yi.zhang@xxxxxxxxxxxxxxx>]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

Current _ext4_show_options() do not distinguish MOPT_2 flag, so it mixed
extend sbi->s_mount_opt2 options with sbi->s_mount_opt, it could lead to
show incorrect options, e.g. show fc_debug_force if we mount with
errors=continue mode and miss it if we set.

  $ mkfs.ext4 /dev/pmem0
  $ mount -o errors=remount-ro /dev/pmem0 /mnt
  $ cat /proc/fs/ext4/pmem0/options | grep fc_debug_force
    #empty
  $ mount -o remount,errors=continue /mnt
  $ cat /proc/fs/ext4/pmem0/options | grep fc_debug_force
    fc_debug_force
  $ mount -o remount,errors=remount-ro,fc_debug_force /mnt
  $ cat /proc/fs/ext4/pmem0/options | grep fc_debug_force
    #empty

Fixes: 995a3ed67fc8 ("ext4: add fast_commit feature and handling for extended mount options")
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/super.c | 28 +++++++++++++++++++++-------
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 140e1eb300d1..6479146140d2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1529,6 +1529,7 @@ struct ext4_sb_info {
 	unsigned int s_mount_opt2;
 	unsigned long s_mount_flags;
 	unsigned int s_def_mount_opt;
+	unsigned int s_def_mount_opt2;
 	ext4_fsblk_t s_sb_block;
 	atomic64_t s_resv_clusters;
 	kuid_t s_resuid;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 260c1b3e3ef2..e6fe416a65a3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2894,7 +2894,7 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
-	int def_errors, def_mount_opt = sbi->s_def_mount_opt;
+	int def_errors;
 	const struct mount_opts *m;
 	char sep = nodefs ? '\n' : ',';
 
@@ -2906,15 +2906,28 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 
 	for (m = ext4_mount_opts; m->token != Opt_err; m++) {
 		int want_set = m->flags & MOPT_SET;
+		int opt_2 = m->flags & MOPT_2;
+		unsigned int mount_opt, def_mount_opt;
+
 		if (((m->flags & (MOPT_SET|MOPT_CLEAR)) == 0) ||
 		    m->flags & MOPT_SKIP)
 			continue;
-		if (!nodefs && !(m->mount_opt & (sbi->s_mount_opt ^ def_mount_opt)))
-			continue; /* skip if same as the default */
+
+		if (opt_2) {
+			mount_opt = sbi->s_mount_opt2;
+			def_mount_opt = sbi->s_def_mount_opt2;
+		} else {
+			mount_opt = sbi->s_mount_opt;
+			def_mount_opt = sbi->s_def_mount_opt;
+		}
+		/* skip if same as the default */
+		if (!nodefs && !(m->mount_opt & (mount_opt ^ def_mount_opt)))
+			continue;
+		/* select Opt_noFoo vs Opt_Foo */
 		if ((want_set &&
-		     (sbi->s_mount_opt & m->mount_opt) != m->mount_opt) ||
-		    (!want_set && (sbi->s_mount_opt & m->mount_opt)))
-			continue; /* select Opt_noFoo vs Opt_Foo */
+		     (mount_opt & m->mount_opt) != m->mount_opt) ||
+		    (!want_set && (mount_opt & m->mount_opt)))
+			continue;
 		SEQ_OPTS_PRINT("%s", token2str(m->token));
 	}
 
@@ -2942,7 +2955,7 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 	if (nodefs || sbi->s_stripe)
 		SEQ_OPTS_PRINT("stripe=%lu", sbi->s_stripe);
 	if (nodefs || EXT4_MOUNT_DATA_FLAGS &
-			(sbi->s_mount_opt ^ def_mount_opt)) {
+			(sbi->s_mount_opt ^ sbi->s_def_mount_opt)) {
 		if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
 			SEQ_OPTS_PUTS("data=journal");
 		else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA)
@@ -5086,6 +5099,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 		goto failed_mount;
 
 	sbi->s_def_mount_opt = sbi->s_mount_opt;
+	sbi->s_def_mount_opt2 = sbi->s_mount_opt2;
 
 	err = ext4_check_opt_consistency(fc, sb);
 	if (err < 0)
-- 
2.31.1