• Mike Snitzer's avatar
    dm thin: fix table output when pool target disables discard passdown internally · f402693d
    Mike Snitzer authored
    When the thin pool target clears the discard_passdown parameter
    internally, it incorrectly changes the table line reported to userspace.
    This breaks dumb string comparisons on these table lines in generic
    userspace device-mapper library code and leads to tables being reloaded
    repeatedly when nothing is actually meant to be changing.
    
    This patch corrects this by no longer changing the table line when
    discard passdown was disabled.
    
    We can still tell when discard passdown is overridden by looking for the
    message "Discard unsupported by data device (sdX): Disabling discard passdown."
    
    This automatic detection is also moved from the 'load' to the 'resume'
    so that it is re-evaluated should the properties of underlying devices
    change.
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    Acked-by: default avatarJoe Thornber <ejt@redhat.com>
    Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
    f402693d
dm-thin.c 65.8 KB