Push lock_super() into the ->remount_fs() of filesystems that care about it

Note that since we can't run into contention between remount_fs and write_super
(due to exclusion on s_umount), we have to care only about filesystems that
touch lock_super() on their own.  Out of those ext3, ext4, hpfs, sysv and ufs
do need it; fat doesn't since its ->remount_fs() only accesses assign-once
data (basically, it's "we have no atime on directories and only have atime on
files for vfat; force nodiratime and possibly noatime into *flags").

[folded a build fix from hch]

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

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1d4180b8677..a9c68342592 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3421,6 +3421,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #endif
 
         /* Store the original options */
+        lock_super(sb);
         old_sb_flags = sb->s_flags;
         old_opts.s_mount_opt = sbi->s_mount_opt;
         old_opts.s_resuid = sbi->s_resuid;
@@ -3554,6 +3555,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
                     old_opts.s_qf_names[i] != sbi->s_qf_names[i])
                         kfree(old_opts.s_qf_names[i]);
 #endif
+        unlock_super(sb);
         return 0;
 
 restore_opts:
@@ -3573,6 +3575,7 @@ restore_opts:
                 sbi->s_qf_names[i] = old_opts.s_qf_names[i];
         }
 #endif
+        unlock_super(sb);
         return err;
 }