Re: [PATCH 13/14] bcache: read jset from NVDIMM pages for journal replay

[Hannes Reinecke <hare@suse.de>]

On 6/15/21 7:49 AM, Coly Li wrote:
> This patch implements two methods to read jset from media for journal
> replay,
> - __jnl_rd_bkt() for block device
>   This is the legacy method to read jset via block device interface.
> - __jnl_rd_nvm_bkt() for NVDIMM
>   This is the method to read jset from NVDIMM memory interface, a.k.a
>   memcopy() from NVDIMM pages to DRAM pages.
> 
> If BCH_FEATURE_INCOMPAT_NVDIMM_META is set in incompat feature set,
> during running cache set, journal_read_bucket() will read the journal
> content from NVDIMM by __jnl_rd_nvm_bkt(). The linear addresses of
> NVDIMM pages to read jset are stored in sb.d[SB_JOURNAL_BUCKETS], which
> were initialized and maintained in previous runs of the cache set.
> 
> A thing should be noticed is, when bch_journal_read() is called, the
> linear address of NVDIMM pages is not loaded and initialized yet, it
> is necessary to call __bch_journal_nvdimm_init() before reading the jset
> from NVDIMM pages.
> 
> Signed-off-by: Coly Li <colyli@suse.de>
> Cc: Jianpeng Ma <jianpeng.ma@intel.com>
> Cc: Qiaowei Ren <qiaowei.ren@intel.com>
> ---
>  drivers/md/bcache/journal.c | 93 +++++++++++++++++++++++++++----------
>  1 file changed, 69 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
> index 03ecedf813b0..23e5ccf125df 100644
> --- a/drivers/md/bcache/journal.c
> +++ b/drivers/md/bcache/journal.c
> @@ -34,60 +34,96 @@ static void journal_read_endio(struct bio *bio)
>  	closure_put(cl);
>  }
>  
> +static struct jset *__jnl_rd_bkt(struct cache *ca, unsigned int bkt_idx,
> +				    unsigned int len, unsigned int offset,
> +				    struct closure *cl)
> +{
> +	sector_t bucket = bucket_to_sector(ca->set, ca->sb.d[bkt_idx]);
> +	struct bio *bio = &ca->journal.bio;
> +	struct jset *data = ca->set->journal.w[0].data;
> +
> +	bio_reset(bio);
> +	bio->bi_iter.bi_sector	= bucket + offset;
> +	bio_set_dev(bio, ca->bdev);
> +	bio->bi_iter.bi_size	= len << 9;
> +	bio->bi_end_io	= journal_read_endio;
> +	bio->bi_private = cl;
> +	bio_set_op_attrs(bio, REQ_OP_READ, 0);
> +	bch_bio_map(bio, data);
> +
> +	closure_bio_submit(ca->set, bio, cl);
> +	closure_sync(cl);
> +
> +	/* Indeed journal.w[0].data */
> +	return data;
> +}
> +
> +#if defined(CONFIG_BCACHE_NVM_PAGES)
> +
> +static struct jset *__jnl_rd_nvm_bkt(struct cache *ca, unsigned int bkt_idx,
> +				     unsigned int len, unsigned int offset)
> +{
> +	void *jset_addr = (void *)ca->sb.d[bkt_idx] + (offset << 9);
> +	struct jset *data = ca->set->journal.w[0].data;
> +
> +	memcpy(data, jset_addr, len << 9);
> +
> +	/* Indeed journal.w[0].data */
> +	return data;
> +}
> +
> +#else /* CONFIG_BCACHE_NVM_PAGES */
> +
> +static struct jset *__jnl_rd_nvm_bkt(struct cache *ca, unsigned int bkt_idx,
> +				     unsigned int len, unsigned int offset)
> +{
> +	return NULL;
> +}
> +
> +#endif /* CONFIG_BCACHE_NVM_PAGES */
> +
>  static int journal_read_bucket(struct cache *ca, struct list_head *list,
> -			       unsigned int bucket_index)
> +			       unsigned int bucket_idx)

This renaming is pointless.

>  {
>  	struct journal_device *ja = &ca->journal;
> -	struct bio *bio = &ja->bio;
>  
>  	struct journal_replay *i;
> -	struct jset *j, *data = ca->set->journal.w[0].data;
> +	struct jset *j;
>  	struct closure cl;
>  	unsigned int len, left, offset = 0;
>  	int ret = 0;
> -	sector_t bucket = bucket_to_sector(ca->set, ca->sb.d[bucket_index]);
>  
>  	closure_init_stack(&cl);
>  
> -	pr_debug("reading %u\n", bucket_index);
> +	pr_debug("reading %u\n", bucket_idx);
>  
>  	while (offset < ca->sb.bucket_size) {
>  reread:		left = ca->sb.bucket_size - offset;
>  		len = min_t(unsigned int, left, PAGE_SECTORS << JSET_BITS);
>  
> -		bio_reset(bio);
> -		bio->bi_iter.bi_sector	= bucket + offset;
> -		bio_set_dev(bio, ca->bdev);
> -		bio->bi_iter.bi_size	= len << 9;
> -
> -		bio->bi_end_io	= journal_read_endio;
> -		bio->bi_private = &cl;
> -		bio_set_op_attrs(bio, REQ_OP_READ, 0);
> -		bch_bio_map(bio, data);
> -
> -		closure_bio_submit(ca->set, bio, &cl);
> -		closure_sync(&cl);
> +		if (!bch_has_feature_nvdimm_meta(&ca->sb))
> +			j = __jnl_rd_bkt(ca, bucket_idx, len, offset, &cl);
> +		else
> +			j = __jnl_rd_nvm_bkt(ca, bucket_idx, len, offset);
>  
>  		/* This function could be simpler now since we no longer write
>  		 * journal entries that overlap bucket boundaries; this means
>  		 * the start of a bucket will always have a valid journal entry
>  		 * if it has any journal entries at all.
>  		 */
> -
> -		j = data;
>  		while (len) {
>  			struct list_head *where;
>  			size_t blocks, bytes = set_bytes(j);
>  
>  			if (j->magic != jset_magic(&ca->sb)) {
> -				pr_debug("%u: bad magic\n", bucket_index);
> +				pr_debug("%u: bad magic\n", bucket_idx);
>  				return ret;
>  			}
>  
>  			if (bytes > left << 9 ||
>  			    bytes > PAGE_SIZE << JSET_BITS) {
>  				pr_info("%u: too big, %zu bytes, offset %u\n",
> -					bucket_index, bytes, offset);
> +					bucket_idx, bytes, offset);
>  				return ret;
>  			}
>  
> @@ -96,7 +132,7 @@ reread:		left = ca->sb.bucket_size - offset;
>  
>  			if (j->csum != csum_set(j)) {
>  				pr_info("%u: bad csum, %zu bytes, offset %u\n",
> -					bucket_index, bytes, offset);
> +					bucket_idx, bytes, offset);
>  				return ret;
>  			}
>  
> @@ -158,8 +194,8 @@ reread:		left = ca->sb.bucket_size - offset;
>  			list_add(&i->list, where);
>  			ret = 1;
>  
> -			if (j->seq > ja->seq[bucket_index])
> -				ja->seq[bucket_index] = j->seq;
> +			if (j->seq > ja->seq[bucket_idx])
> +				ja->seq[bucket_idx] = j->seq;
>  next_set:
>  			offset	+= blocks * ca->sb.block_size;
>  			len	-= blocks * ca->sb.block_size;
> @@ -170,6 +206,8 @@ reread:		left = ca->sb.bucket_size - offset;
>  	return ret;
>  }
>  
> +static int __bch_journal_nvdimm_init(struct cache *ca);
> +
>  int bch_journal_read(struct cache_set *c, struct list_head *list)
>  {
>  #define read_bucket(b)							\
> @@ -188,6 +226,13 @@ int bch_journal_read(struct cache_set *c, struct list_head *list)
>  	unsigned int i, l, r, m;
>  	uint64_t seq;
>  
> +	/*
> +	 * Linear addresses of NVDIMM pages for journaling is not
> +	 * initialized yet, do it before read jset from NVDIMM pages.
> +	 */
> +	if (bch_has_feature_nvdimm_meta(&ca->sb))
> +		__bch_journal_nvdimm_init(ca);
> +
>  	bitmap_zero(bitmap, SB_JOURNAL_BUCKETS);
>  	pr_debug("%u journal buckets\n", ca->sb.njournal_buckets);
>  
> 
Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer