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Date:   Tue, 13 Apr 2021 10:51:14 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mike Snitzer <snitzer@redhat.com>, kernel-team@android.com,
        agk@redhat.com, dm-devel@redhat.com
Cc:     stable@vger.kernel.org
Subject: Re: [PATCH] dm verity: fix not aligned logical block size of RS
 roots IO
Message-ID: <YHXaEiRt8QzX8h9m@google.com>
References: <20210412181123.2550918-1-jaegeuk@kernel.org>
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On 04/12, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <jaegeuk@google.com>
> 
> commit df7b59ba9245 ("dm verity: fix FEC for RS roots unaligned to block size")
> made dm_bufio->block_size 1024, if f->roots is 2. But, that gives the below EIO
> if the logical block size of the device is 4096, given v->data_dev_block_bits=12.
> 
> E sd 0    : 0:0:0: [sda] tag#30 request not aligned to the logical block size
> E blk_update_request: I/O error, dev sda, sector 10368424 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
> E device-mapper: verity-fec: 254:8: FEC 9244672: parity read failed (block 18056): -5
> 
> Let's use f->roots for dm_bufio iff it's aligned to v->data_dev_block_bits.
> 
> Fixes: df7b59ba9245 ("dm verity: fix FEC for RS roots unaligned to block size")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> ---
>  drivers/md/dm-verity-fec.c | 11 ++++++++---
>  drivers/md/dm-verity-fec.h |  1 +
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
> index 66f4c6398f67..cea2b3789736 100644
> --- a/drivers/md/dm-verity-fec.c
> +++ b/drivers/md/dm-verity-fec.c
> @@ -65,7 +65,7 @@ static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index,
>  	u8 *res;
>  
>  	position = (index + rsb) * v->fec->roots;
> -	block = div64_u64_rem(position, v->fec->roots << SECTOR_SHIFT, &rem);
> +	block = div64_u64_rem(position, v->fec->io_size, &rem);
>  	*offset = (unsigned)rem;
>  
>  	res = dm_bufio_read(v->fec->bufio, block, buf);
> @@ -154,7 +154,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio,
>  
>  		/* read the next block when we run out of parity bytes */
>  		offset += v->fec->roots;
> -		if (offset >= v->fec->roots << SECTOR_SHIFT) {
> +		if (offset >= v->fec->io_size) {
>  			dm_bufio_release(buf);
>  
>  			par = fec_read_parity(v, rsb, block_offset, &offset, &buf);
> @@ -742,8 +742,13 @@ int verity_fec_ctr(struct dm_verity *v)
>  		return -E2BIG;
>  	}
>  
> +	if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1))
> +		f->io_size = 1 << v->data_dev_block_bits;
> +	else
> +		f->io_size = v->fec->roots << SECTOR_SHIFT;
> +
>  	f->bufio = dm_bufio_client_create(f->dev->bdev,
> -					  f->roots << SECTOR_SHIFT,
> +					  f->io_size,
>  					  1, 0, NULL, NULL);
>  	if (IS_ERR(f->bufio)) {
>  		ti->error = "Cannot initialize FEC bufio client";
> diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h
> index 42fbd3a7fc9f..3c46c8d61883 100644
> --- a/drivers/md/dm-verity-fec.h
> +++ b/drivers/md/dm-verity-fec.h
> @@ -36,6 +36,7 @@ struct dm_verity_fec {
>  	struct dm_dev *dev;	/* parity data device */
>  	struct dm_bufio_client *data_bufio;	/* for data dev access */
>  	struct dm_bufio_client *bufio;		/* for parity data access */
> +	size_t io_size;		/* IO size for roots */
>  	sector_t start;		/* parity data start in blocks */
>  	sector_t blocks;	/* number of blocks covered */
>  	sector_t rounds;	/* number of interleaving rounds */
> -- 
> 2.31.1.295.g9ea45b61b8-goog