On Wed, Feb 24, 2010 at 05:56:46PM +0100, Jan Kara wrote: > OK, I see that in theory a process can open file for writing after > fs_may_remount_ro() before MS_RDONLY flag gets set. That could be really > nasty. Not just in theory, but also in practice. We can easily hit this under load with XFS. > But by no means we should solve this VFS problem by spilling error > messages from the filesystem. Exactly. > Al, Christoph, do I miss something or there is really nothing which > prevents a process from opening a file after the fs_may_remount_ro() check > in do_remount_sb()? No, there is nothing. We really do need a multi-stage remount read-only process: 1) stop any writes from userland, that is opening new files writeable 2) stop any periodic writeback from the VM or filesystem-internal 3) write out all filesystem data and metadata 4) mark the filesystem fully read-only -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
