• NeilBrown's avatar
    md/raid1: Don't use next_resync to determine how far resync has progressed · 23554960
    NeilBrown authored
    next_resync is (approximately) the location for the next resync request.
    However it does *not* reliably determine the earliest location
    at which resync might be happening.
    This is because resync requests can complete out of order, and
    we only limit the number of current requests, not the distance
    from the earliest pending request to the latest.
    
    mddev->curr_resync_completed is a reliable indicator of the earliest
    position at which resync could be happening.   It is updated less
    frequently, but is actually reliable which is more important.
    
    So use it to determine if a write request is before the region
    being resynced and so safe from conflict.
    
    This error can allow resync IO to interfere with normal IO which
    could lead to data corruption. Hence: stable.
    
    Fixes: 79ef3a8a
    cc: stable@vger.kernel.org (v3.13+)
    Signed-off-by: default avatarNeilBrown <neilb@suse.de>
    23554960
raid1.c 86.9 KB