fs/super.c: sync ro remount after blocking writers

Move sync_filesystem() after sb_prepare_remount_readonly().  If writers
sneak in anywhere from sync_filesystem() to sb_prepare_remount_readonly()
it can cause inodes to be dirtied and writeback to occur well after
sys_mount() has completely successfully.

This was spotted by corrupted ubifs filesystems on reboot, but appears
that it can cause issues with any filesystem using writeback.

Cc: Artem Bityutskiy <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Alexander Viro <[email protected]>
CC: Richard Weinberger <[email protected]>
Co-authored-by: Richard Weinberger <[email protected]>
Signed-off-by: Andrew Ruder <[email protected]>
Signed-off-by: Al Viro <[email protected]>

0 files changed, 0 insertions, 0 deletions