On Wed, Sep 06, 2017 at 11:02:35AM +0800, Dennis Yang wrote: > In release_stripe_plug(), if a stripe_head has its STRIPE_ON_UNPLUG_LIST > set, it indicates that this stripe_head is already in the raid5_plug_cb > list and release_stripe() would be called instead to drop a reference > count. Otherwise, the STRIPE_ON_UNPLUG_LIST bit would be set for this > stripe_head and it will get queued into the raid5_plug_cb list. > > Since break_stripe_batch_list() did not preserve STRIPE_ON_UNPLUG_LIST, > A stripe could be re-added to plug list while it is still on that list > in the following situation. If stripe_head A is added to another > stripe_head B's batch list, in this case A will have its > batch_head != NULL and be added into the plug list. After that, > stripe_head B gets handled and called break_stripe_batch_list() to > reset all the batched stripe_head(including A which is still on > the plug list)'s state and reset their batch_head to NULL. > Before the plug list gets processed, if there is another write request > comes in and get stripe_head A, A will have its batch_head == NULL > (cleared by calling break_stripe_batch_list() on B) and be added to > plug list once again. applied, thanks! > Signed-off-by: Dennis Yang <dennisyang@xxxxxxxx> > --- > drivers/md/raid5.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index e92dd2d..faf3cfd 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -4611,7 +4611,8 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, > > set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS | > (1 << STRIPE_PREREAD_ACTIVE) | > - (1 << STRIPE_DEGRADED)), > + (1 << STRIPE_DEGRADED) | > + (1 << STRIPE_ON_UNPLUG_LIST)), > head_sh->state & (1 << STRIPE_INSYNC)); > > sh->check_state = head_sh->check_state; > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
