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SubjectRe: [PATCH] md: bitwise operations might not fit in a "bool"
On Thu, 22 Jul 2010 14:44:53 +0300
Boaz Harrosh <bharrosh@panasas.com> wrote:

>
> when taking a resolute of a bit-wise AND as true false. Better / faster
> to make it a boolean operation.
>
> This fixes a bug and a crash because the flags field did not fit into
> the bool operands.

No, that won't work.
Read the rest of the code and see where 'do_sync' and 'do_barriers' are used.

NeilBrown

>
> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
> ---
> git diff --stat -p -M drivers/md/raid1.c
> drivers/md/raid1.c | 11 +++++++----
> 1 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 73cc74f..67a9159 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -787,7 +787,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
> struct bio_list bl;
> struct page **behind_pages = NULL;
> const int rw = bio_data_dir(bio);
> - const bool do_sync = (bio->bi_rw & REQ_SYNC);
> + const bool do_sync = (bio->bi_rw & REQ_SYNC) != 0;
> bool do_barriers;
> mdk_rdev_t *blocked_rdev;
>
> @@ -959,7 +959,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
> atomic_set(&r1_bio->remaining, 0);
> atomic_set(&r1_bio->behind_remaining, 0);
>
> - do_barriers = bio->bi_rw & REQ_HARDBARRIER;
> + do_barriers = (bio->bi_rw & REQ_HARDBARRIER) != 0;
> if (do_barriers)
> set_bit(R1BIO_Barrier, &r1_bio->state);
>
> @@ -1640,7 +1640,8 @@ static void raid1d(mddev_t *mddev)
> * We already have a nr_pending reference on these rdevs.
> */
> int i;
> - const bool do_sync = (r1_bio->master_bio->bi_rw & REQ_SYNC);
> + const bool do_sync =
> + (r1_bio->master_bio->bi_rw & REQ_SYNC) != 0;
> clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
> clear_bit(R1BIO_Barrier, &r1_bio->state);
> for (i=0; i < conf->raid_disks; i++)
> @@ -1696,7 +1697,9 @@ static void raid1d(mddev_t *mddev)
> (unsigned long long)r1_bio->sector);
> raid_end_bio_io(r1_bio);
> } else {
> - const bool do_sync = r1_bio->master_bio->bi_rw & REQ_SYNC;
> + const bool do_sync =
> + (r1_bio->master_bio->bi_rw & REQ_SYNC)
> + != 0;
> r1_bio->bios[r1_bio->read_disk] =
> mddev->ro ? IO_BLOCKED : NULL;
> r1_bio->read_disk = disk;



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