Re: [PATCH 2/4] bio-integrity: introduce two funcs handle protect information

From: Bob Liu <bob.liu@oracle.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-block@vger.kernel.org, axboe@kernel.dk,
	martin.petersen@oracle.com, linux-fsdevel@vger.kernel.org,
	io-uring@vger.kernel.org
Subject: Re: [PATCH 2/4] bio-integrity: introduce two funcs handle protect information
Date: Thu, 27 Feb 2020 17:23:22 +0800	[thread overview]
Message-ID: <fb215042-6882-d51c-0ff9-a8d2487db08f@oracle.com> (raw)
In-Reply-To: <20200226160310.GA8044@magnolia>

On 2/27/20 12:03 AM, Darrick J. Wong wrote:
> On Wed, Feb 26, 2020 at 04:37:17PM +0800, Bob Liu wrote:
>> Introduce two funcs handle protect information passthrough from
>> user space.
>>
>> iter_slice_protect_info() will slice the last segment as protect
>> information.
>>
>> bio_integrity_prep_from_iovec() attach the protect information to
>> a bio.
>>
>> Signed-off-by: Bob Liu <bob.liu@oracle.com>
>> ---
>>  block/bio-integrity.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/bio.h   | 14 ++++++++++
>>  2 files changed, 91 insertions(+)
>>
>> diff --git a/block/bio-integrity.c b/block/bio-integrity.c
>> index 575df98..0b22c5d 100644
>> --- a/block/bio-integrity.c
>> +++ b/block/bio-integrity.c
>> @@ -12,6 +12,7 @@
>>  #include <linux/bio.h>
>>  #include <linux/workqueue.h>
>>  #include <linux/slab.h>
>> +#include <linux/uio.h>
>>  #include "blk.h"
>>  
>>  #define BIP_INLINE_VECS	4
>> @@ -305,6 +306,53 @@ bool bio_integrity_prep(struct bio *bio)
>>  }
>>  EXPORT_SYMBOL(bio_integrity_prep);
>>  
>> +int bio_integrity_prep_from_iovec(struct bio *bio, struct iovec *pi_iov)
>> +{
>> +	struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
>> +	struct bio_integrity_payload *bip;
>> +	struct page *user_pi_page;
>> +	int nr_vec_page = 0;
>> +	int ret = 0, interval = 0;
>> +
>> +	if (!pi_iov || !pi_iov->iov_base)
>> +		return 1;
>> +
>> +	nr_vec_page = (pi_iov->iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> +	if (nr_vec_page > 1) {
>> +		printk("Now only support 1 page containing integrity "
>> +			"metadata, while requires %d pages.\n", nr_vec_page);
>> +		return 1;
> 
> I would've thought this would be -EINVAL or something given the -ENOMEM
> below...?
> 
>> +	}
>> +
>> +	interval = bio_integrity_intervals(bi, bio_sectors(bio));
>> +	if ((interval * bi->tuple_size) != pi_iov->iov_len)
>> +		return 1;
>> +
>> +	bip = bio_integrity_alloc(bio, GFP_NOIO, nr_vec_page);
>> +	if (IS_ERR(bip))
>> +		return PTR_ERR(bip);
>> +
>> +	bip->bip_iter.bi_size = pi_iov->iov_len;
>> +	bip->bio_iter = bio->bi_iter;
>> +	bip_set_seed(bip, bio->bi_iter.bi_sector);
>> +
>> +	if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
>> +		bip->bip_flags |= BIP_IP_CHECKSUM;
>> +
>> +	ret = get_user_pages_fast((unsigned long)(pi_iov->iov_base), nr_vec_page,
>> +			op_is_write(bio_op(bio)) ?  FOLL_WRITE : 0,
>> +			&user_pi_page);
>> +	if (unlikely(ret < 0))
>> +		return 1;
>> +
>> +	ret = bio_integrity_add_page(bio, user_pi_page, pi_iov->iov_len, 0);
>> +	if (unlikely(ret != pi_iov->iov_len))
>> +		return -ENOMEM;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(bio_integrity_prep_from_iovec);
>> +
>>  /**
>>   * bio_integrity_verify_fn - Integrity I/O completion worker
>>   * @work:	Work struct stored in bio to be verified
>> @@ -378,6 +426,35 @@ void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
>>  }
>>  
>>  /**
>> + * iter_slice_protect_info
>> + *
>> + * Description: slice protection information from iter.
>> + * The last iovec contains protection information pass from user space.
> 
> What do the return values here mean?
> 

Will update.

> Also kinda wondering about the slice & dice of the iovec here, but
> <shrug> I guess this is RFC. :)
> 

Hmm, I also very hesitate to put it here or lib/iov_iter.c. 

> --D
> 
>> + */
>> +int iter_slice_protect_info(struct iov_iter *iter, int nr_pages,
>> +		struct iovec **pi_iov)
>> +{
>> +	size_t len = 0;
>> +
>> +	/* TBD: now only support one bio. */
>> +	if (!iter_is_iovec(iter) || nr_pages >= BIO_MAX_PAGES - 1)
>> +		return 1;
>> +
>> +	/* Last iovec contains protection information. */
>> +	iter->nr_segs--;
>> +	*pi_iov = (struct iovec *)(iter->iov + iter->nr_segs);
>> +
>> +	len = (*pi_iov)->iov_len;
>> +	if (len > 0 && len < iter->count) {
>> +		iter->count -= len;
>> +		return 0;
>> +	}
>> +
>> +	return 1;
>> +}
>> +EXPORT_SYMBOL(iter_slice_protect_info);
>> +
>> +/**
>>   * bio_integrity_trim - Trim integrity vector
>>   * @bio:	bio whose integrity vector to update
>>   *
>> diff --git a/include/linux/bio.h b/include/linux/bio.h
>> index 3cdb84c..6172b13 100644
>> --- a/include/linux/bio.h
>> +++ b/include/linux/bio.h
>> @@ -749,6 +749,8 @@ static inline bool bioset_initialized(struct bio_set *bs)
>>  extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
>>  extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
>>  extern bool bio_integrity_prep(struct bio *);
>> +extern int bio_integrity_prep_from_iovec(struct bio *bio, struct iovec *pi_iov);
>> +extern int iter_slice_protect_info(struct iov_iter *iter, int nr_pages, struct iovec **pi_iov);
>>  extern void bio_integrity_advance(struct bio *, unsigned int);
>>  extern void bio_integrity_trim(struct bio *);
>>  extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
>> @@ -778,6 +780,18 @@ static inline bool bio_integrity_prep(struct bio *bio)
>>  	return true;
>>  }
>>  
>> +static inline int bio_integrity_prep_from_iovec(struct bio *bio,
>> +		struct iovec *pi_iov)
>> +{
>> +	return 0;
>> +}
>> +
>> +static inline int iter_slice_protect_info(struct iov_iter *iter, int nr_pages,
>> +		struct iovec **pi_iov)
>> +{
>> +	return 0;
>> +}
>> +
>>  static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
>>  				      gfp_t gfp_mask)
>>  {
>> -- 
>> 2.9.5
>>