Re: [PATCH v2 12/26] raid1: use bio_reset()

From: Kent Overstreet
Date: Tue Sep 11 2012 - 14:28:22 EST


On Tue, Sep 11, 2012 at 02:59:13PM +1000, NeilBrown wrote:
> On Mon, 10 Sep 2012 17:22:23 -0700 Kent Overstreet <koverstreet@xxxxxxxxxx>
> wrote:
>
> > I couldn't figure out what sbio->bi_end_io in process_checks() was
> > supposed to be, so I took the easy way out.
>
> Almost.
> You save 'sbio->bi_end_io' to 'bi_end_io', then do nothing with it...

Whoops :) I think I must've gotten distracted and forgot to finish with
that patch, I wasn't setting bi_private either.

>
> A little way above the 'fixup the bio for reuse' comment you'll find:
>
> struct bio *sbio = r1_bio->bios[i];
> ....
> if (r1_bio->bios[i]->bi_end_io != end_sync_read)
> continue;
>
> which implies that if we don't 'continue', then sbio->bi_end_io ==
> end_sync_read.

Ahh. I remember reading that, but I missed that that was sbio that was
being checked.

>
> So I suspect you want to add
> sbio->bi_end_io = end_sync_read;
> somewhere after the 'bio_reset()'.
>
> If you happened to also fix that 'if' that I quoted so that it reads:
>
> if (sbio->bi_end_io != end_sync_read)
> continue;

Will do! How's this look?


commit 40a4645a4346edd040066baedcf2184ac4211ba7
Author: Kent Overstreet <koverstreet@xxxxxxxxxx>
Date: Tue Sep 11 11:26:12 2012 -0700

raid1: use bio_reset()

Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
CC: Jens Axboe <axboe@xxxxxxxxx>
CC: NeilBrown <neilb@xxxxxxx>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ee85154..df68691 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1851,7 +1851,7 @@ static int process_checks(struct r1bio *r1_bio)
struct bio *sbio = r1_bio->bios[i];
int size;

- if (r1_bio->bios[i]->bi_end_io != end_sync_read)
+ if (sbio->bi_end_io != end_sync_read)
continue;

if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
@@ -1876,16 +1876,15 @@ static int process_checks(struct r1bio *r1_bio)
continue;
}
/* fixup the bio for reuse */
+ bio_reset(sbio);
sbio->bi_vcnt = vcnt;
sbio->bi_size = r1_bio->sectors << 9;
- sbio->bi_idx = 0;
- sbio->bi_phys_segments = 0;
- sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
- sbio->bi_flags |= 1 << BIO_UPTODATE;
- sbio->bi_next = NULL;
sbio->bi_sector = r1_bio->sector +
conf->mirrors[i].rdev->data_offset;
sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
+ sbio->bi_end_io = end_sync_read;
+ sbio->bi_private = r1_bio;
+
size = sbio->bi_size;
for (j = 0; j < vcnt ; j++) {
struct bio_vec *bi;
@@ -2426,18 +2425,7 @@ static sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipp
for (i = 0; i < conf->raid_disks * 2; i++) {
struct md_rdev *rdev;
bio = r1_bio->bios[i];
-
- /* take from bio_init */
- bio->bi_next = NULL;
- bio->bi_flags &= ~(BIO_POOL_MASK-1);
- bio->bi_flags |= 1 << BIO_UPTODATE;
- bio->bi_rw = READ;
- bio->bi_vcnt = 0;
- bio->bi_idx = 0;
- bio->bi_phys_segments = 0;
- bio->bi_size = 0;
- bio->bi_end_io = NULL;
- bio->bi_private = NULL;
+ bio_reset(bio);

rdev = rcu_dereference(conf->mirrors[i].rdev);
if (rdev == NULL ||
--
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