linux-kernel - Re: [patch] md: Fix non-zero bio->bi_size in MD's bi_end

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Date:	Wed, 9 Sep 2009 20:40:33 +1000 (EST)
From:	"NeilBrown" <neilb@...e.de>
To:	"Max Lapan" <max.lapan@...il.com>
Cc:	"LKML" <linux-kernel@...r.kernel.org>
Subject: Re: [patch] md: Fix non-zero bio->bi_size in MD's bi_end_io 
     callback.

On Wed, September 9, 2009 6:46 pm, Max Lapan wrote:
> Neil,
>
> bi_size value in MD's BIO object passed in bi_end_io callback is not
> null for successfully completed
> BIOs. This may confuse upper layer which may check for bi_size (at the
> moment, the only confused FS is GPFS).

Since about commit 6712ecf8f648118c3363c142196418f89a510b90
(2 years ago), the value of bi_size is undefined once the request
gets to bi_end_io.

So fix GPFS.

NeilBrown


>
>     Signed-off-by: Max Lapan <max.lapan@...il.com>
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 8726fd7..b95e9a2 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -242,6 +242,8 @@ static void raid_end_bio_io(r1bio_t *r1_bio)
>  			(unsigned long long) bio->bi_sector +
>  				(bio->bi_size >> 9) - 1);
>
> +		if (test_bit(R1BIO_Uptodate, &r1_bio->state))
> +			bio->bi_size = 0;
>  		bio_endio(bio,
>  			test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
>  	}
> @@ -364,6 +366,7 @@ static void raid1_end_write_request(struct bio
> *bio, int error)
>  					       (unsigned long long) mbio->bi_sector,
>  					       (unsigned long long) mbio->bi_sector +
>  					       (mbio->bi_size >> 9) - 1);
> +					mbio->bi_size = 0;
>  					bio_endio(mbio, 0);
>  				}
>  			}
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 3d9020c..ebe883b 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -235,6 +235,8 @@ static void raid_end_bio_io(r10bio_t *r10_bio)
>  {
>  	struct bio *bio = r10_bio->master_bio;
>
> +	if (test_bit(R10BIO_Uptodate, &r10_bio->state))
> +		bio->bi_size = 0;
>  	bio_endio(bio,
>  		test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
>  	free_r10bio(r10_bio);
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index b8a2c5d..fb9560d 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -3446,6 +3446,7 @@ static void raid5_align_endio(struct bio *bi, int
> error)
>  	rdev_dec_pending(rdev, conf->mddev);
>
>  	if (!error && uptodate) {
> +		raid_bi->bi_size = 0;
>  		bio_endio(raid_bi, 0);
>  		if (atomic_dec_and_test(&conf->active_aligned_reads))
>  			wake_up(&conf->wait_for_stripe);
> @@ -3747,7 +3748,7 @@ static int make_request(struct request_queue *q,
> struct bio * bi)
>
>  		if ( rw == WRITE )
>  			md_write_end(mddev);
> -
> +		bi->bi_size = 0;
>  		bio_endio(bi, 0);
>  	}
>  	return 0;
> @@ -4121,8 +4122,10 @@ static int  retry_aligned_read(raid5_conf_t
> *conf, struct bio *raid_bio)
>  	spin_lock_irq(&conf->device_lock);
>  	remaining = raid5_dec_bi_phys_segments(raid_bio);
>  	spin_unlock_irq(&conf->device_lock);
> -	if (remaining == 0)
> +	if (remaining == 0) {
> +		raid_bio->bi_size = 0;
>  		bio_endio(raid_bio, 0);
> +	}
>  	if (atomic_dec_and_test(&conf->active_aligned_reads))
>  		wake_up(&conf->wait_for_stripe);
>  	return handled;
>

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