• Dave Chinner's avatar
    xfs: reclaim all inodes by background tree walks · 57817c68
    Dave Chinner authored
    We cannot do direct inode reclaim without taking the flush lock to
    ensure that we do not reclaim an inode under IO. We check the inode
    is clean before doing direct reclaim, but this is not good enough
    because the inode flush code marks the inode clean once it has
    copied the in-core dirty state to the backing buffer.
    It is the flush lock that determines whether the inode is still
    under IO, even though it is marked clean, and the inode is still
    required at IO completion so we can't reclaim it even though it is
    clean in core. Hence the requirement that we need to take the flush
    lock even on clean inodes because this guarantees that the inode
    writeback IO has completed and it is safe to reclaim the inode.
    With delayed write inode flushing, we coul dend up waiting a long
    time on the flush lock even for a clean inode. The background
    reclaim already handles this efficiently, so avoid all the problems
    by killing the direct reclaim path altogether.
    Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
    Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarAlex Elder <aelder@sgi.com>