RE: [bch-nvm-pages v7 3/6] bcache: initialization of the buddy

["Ma, Jianpeng" <jianpeng.ma@intel.com>]

> -----Original Message-----
> From: Coly Li <colyli@suse.de>
> Sent: Monday, March 29, 2021 7:10 PM
> To: Ren, Qiaowei <qiaowei.ren@intel.com>; Ma, Jianpeng
> <jianpeng.ma@intel.com>
> Cc: linux-bcache@vger.kernel.org
> Subject: Re: [bch-nvm-pages v7 3/6] bcache: initialization of the buddy
> 
> On 3/17/21 11:10 PM, Qiaowei Ren wrote:
> > From: Jianpeng Ma <jianpeng.ma@intel.com>
> >
> > This nvm pages allocator will implement the simple buddy to manage the
> > nvm address space. This patch initializes this buddy for new namespace.
> >
> > the unit of alloc/free of the buddy is page. DAX device has their
> > struct page(in dram or PMEM).
> >
> > 	struct {        /* ZONE_DEVICE pages */
> > 		/** @pgmap: Points to the hosting device page map. */
> > 		struct dev_pagemap *pgmap;
> > 		void *zone_device_data;
> > 		/*
> > 		 * ZONE_DEVICE private pages are counted as being
> > 		 * mapped so the next 3 words hold the mapping, index,
> > 		 * and private fields from the source anonymous or
> > 		 * page cache page while the page is migrated to device
> > 		 * private memory.
> > 		 * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also
> > 		 * use the mapping, index, and private fields when
> > 		 * pmem backed DAX files are mapped.
> > 		 */
> > 	};
> >
> > ZONE_DEVICE pages only use pgmap. Other 4 words[16/32 bytes] don't use.
> > So the second/third word will be used as 'struct list_head ' which
> > list in buddy. The fourth word(that is normal struct page::index)
> > store pgoff which the page-offset in the dax device. And the fifth
> > word (that is normal struct page::private) store order of buddy.
> > page_type will be used to store buddy flags.
> >
> > Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
> > Co-authored-by: Qiaowei Ren <qiaowei.ren@intel.com>
> > ---
> >  drivers/md/bcache/nvm-pages.c   | 142
> +++++++++++++++++++++++++++++++-
> >  drivers/md/bcache/nvm-pages.h   |   6 ++
> >  include/uapi/linux/bcache-nvm.h |   8 ++
> >  3 files changed, 152 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/md/bcache/nvm-pages.c
> > b/drivers/md/bcache/nvm-pages.c index 9335371c9d91..1f99965920a1
> > 100644
> > --- a/drivers/md/bcache/nvm-pages.c
> > +++ b/drivers/md/bcache/nvm-pages.c
> > @@ -41,6 +41,10 @@ static void release_nvm_namespaces(struct
> bch_nvm_set *nvm_set)
> >  	for (i = 0; i < nvm_set->total_namespaces_nr; i++) {
> >  		ns = nvm_set->nss[i];
> >  		if (ns) {
> > +			kvfree(ns->pages_bitmap);
> > +			if (ns->pgalloc_recs_bitmap)
> > +				bitmap_free(ns->pgalloc_recs_bitmap);
> > +
> >  			blkdev_put(ns->bdev,
> FMODE_READ|FMODE_WRITE|FMODE_EXEC);
> >  			kfree(ns);
> >  		}
> > @@ -55,17 +59,122 @@ static void release_nvm_set(struct bch_nvm_set
> *nvm_set)
> >  	kfree(nvm_set);
> >  }
> >
> > +static struct page *nvm_vaddr_to_page(struct bch_nvm_namespace *ns,
> > +void *addr) {
> > +	return virt_to_page(addr);
> > +}
> > +
> > +static void *nvm_pgoff_to_vaddr(struct bch_nvm_namespace *ns,
> pgoff_t
> > +pgoff) {
> > +	return ns->kaddr + (pgoff << PAGE_SHIFT); }
> > +
> > +static inline void remove_owner_space(struct bch_nvm_namespace *ns,
> > +					pgoff_t pgoff, u32 nr)
> > +{
> > +	bitmap_set(ns->pages_bitmap, pgoff, nr); }
> > +
> >  static int init_owner_info(struct bch_nvm_namespace *ns)  {
> >  	struct bch_owner_list_head *owner_list_head =
> > ns->sb->owner_list_head;
> > +	struct bch_nvm_pgalloc_recs *sys_recs;
> > +	int i, j, k, rc = 0;
> >
> >  	mutex_lock(&only_set->lock);
> >  	only_set->owner_list_head = owner_list_head;
> >  	only_set->owner_list_size = owner_list_head->size;
> >  	only_set->owner_list_used = owner_list_head->used;
> > +
> > +	/*remove used space*/
> > +	remove_owner_space(ns, 0, ns->pages_offset/ns->page_size);
> > +
> > +	sys_recs = ns->kaddr + BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET;
> > +	// suppose no hole in array
> 
> We don't use such code comments format, please follow the comments style
> of existing bcache code.
> 
> There are also other locations using "//" for code comments, they should be
> modified as well.
> 
Got it, I'll modify those wrong formant in the V8.

Thanks!
Jianpeng.
> Thanks.
> 
> Coly Li
> 
> 
> [snipped]