queue-5.15/exfat-fix-remount-failure-in-different-process-envir.patch

From e3ed690259226de56ff2947b7d734747a16548dc Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 28 Nov 2025 17:51:10 +0800
Subject: exfat: fix remount failure in different process environments

From: Yuezhang Mo <Yuezhang.Mo@sony.com>

[ Upstream commit 51fc7b4ce10ccab8ea5e4876bcdc42cf5202a0ef ]

The kernel test robot reported that the exFAT remount operation
failed. The reason for the failure was that the process's umask
is different between mount and remount, causing fs_fmask and
fs_dmask are changed.

Potentially, both gid and uid may also be changed. Therefore, when
initializing fs_context for remount, inherit these mount options
from the options used during mount.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202511251637.81670f5c-lkp@intel.com
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/exfat/super.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 816ba7e1607f..39e999c0de75 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -758,10 +758,21 @@ static int exfat_init_fs_context(struct fs_context *fc)
 	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
 			DEFAULT_RATELIMIT_BURST);
 
-	sbi->options.fs_uid = current_uid();
-	sbi->options.fs_gid = current_gid();
-	sbi->options.fs_fmask = current->fs->umask;
-	sbi->options.fs_dmask = current->fs->umask;
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE && fc->root) {
+		struct super_block *sb = fc->root->d_sb;
+		struct exfat_mount_options *cur_opts = &EXFAT_SB(sb)->options;
+
+		sbi->options.fs_uid = cur_opts->fs_uid;
+		sbi->options.fs_gid = cur_opts->fs_gid;
+		sbi->options.fs_fmask = cur_opts->fs_fmask;
+		sbi->options.fs_dmask = cur_opts->fs_dmask;
+	} else {
+		sbi->options.fs_uid = current_uid();
+		sbi->options.fs_gid = current_gid();
+		sbi->options.fs_fmask = current->fs->umask;
+		sbi->options.fs_dmask = current->fs->umask;
+	}
+
 	sbi->options.allow_utime = -1;
 	sbi->options.iocharset = exfat_default_iocharset;
 	sbi->options.errors = EXFAT_ERRORS_RO;
-- 
2.51.0