Make sure that all callers of remount hold s_umount exclusive

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/super.c b/fs/super.c
index cb19fffc7681..49f670cb9a83 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -579,7 +579,7 @@ static void do_emergency_remount(struct work_struct *work)
         list_for_each_entry(sb, &super_blocks, s_list) {
                 sb->s_count++;
                 spin_unlock(&sb_lock);
-                down_read(&sb->s_umount);
+                down_write(&sb->s_umount);
                 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
                         /*
                          * ->remount_fs needs lock_kernel().
@@ -590,7 +590,8 @@ static void do_emergency_remount(struct work_struct *work)
                         do_remount_sb(sb, MS_RDONLY, NULL, 1);
                         unlock_kernel();
                 }
-                drop_super(sb);
+                up_write(&sb->s_umount);
+                put_super(sb);
                 spin_lock(&sb_lock);
         }
         spin_unlock(&sb_lock);