Thread (11 messages) 11 messages, 6 authors, 2010-07-27

Re: [PATCH] md: bitwise operations might not fit in a "bool"

From: Neil Brown <hidden>
Date: 2010-07-22 11:56:09
Also in: linux-scsi, lkml

On Thu, 22 Jul 2010 14:44:53 +0300
Boaz Harrosh [off-list ref] 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
quoted hunk ↗ jump to hunk
Signed-off-by: Boaz Harrosh <redacted>
---
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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