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    Subject[patch 18/40] md: raid5: fix clearing of biofill operations

    -stable review patch. If anyone has any objections, please let us know.

    ------------------

    From: Dan Williams <dan.j.williams@intel.com>

    raid5: fix clearing of biofill operations

    This is the correct merge of the two upstream patches for this issue (it
    was mis-merged...)

    ops_complete_biofill() runs outside of spin_lock(&sh->lock) and clears the
    'pending' and 'ack' bits. Since the test_and_ack_op() macro only checks
    against 'complete' it can get an inconsistent snapshot of pending work.

    Move the clearing of these bits to handle_stripe5(), under the lock.

    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Tested-by: Joel Bertrand <joel.bertrand@systella.fr>
    Signed-off-by: Neil Brown <neilb@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    drivers/md/raid5.c | 17 ++++++++++++++---
    1 file changed, 14 insertions(+), 3 deletions(-)

    --- a/drivers/md/raid5.c
    +++ b/drivers/md/raid5.c
    @@ -377,7 +377,12 @@ static unsigned long get_stripe_work(str
    ack++;

    sh->ops.count -= ack;
    - BUG_ON(sh->ops.count < 0);
    + if (unlikely(sh->ops.count < 0)) {
    + printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
    + "ops.complete: %#lx\n", pending, sh->ops.pending,
    + sh->ops.ack, sh->ops.complete);
    + BUG();
    + }

    return pending;
    }
    @@ -551,8 +556,7 @@ static void ops_complete_biofill(void *s
    }
    }
    }
    - clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
    - clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
    + set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);

    return_io(return_bi);

    @@ -2630,6 +2634,13 @@ static void handle_stripe5(struct stripe
    s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
    /* Now to look around and see what can be done */

    + /* clean-up completed biofill operations */
    + if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
    + clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
    + clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
    + clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
    + }
    +
    rcu_read_lock();
    for (i=disks; i--; ) {
    mdk_rdev_t *rdev;
    --
    -
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