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Message-ID: <alpine.DEB.2.02.1507161610570.17378@kaball.uk.xensource.com>
Date: Thu, 16 Jul 2015 16:11:40 +0100
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
To: Julien Grall <julien.grall@...rix.com>
CC: <xen-devel@...ts.xenproject.org>,
<linux-arm-kernel@...ts.infradead.org>, <ian.campbell@...rix.com>,
<stefano.stabellini@...citrix.com>, <linux-kernel@...r.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Roger Pau Monné <roger.pau@...rix.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
"David Vrabel" <david.vrabel@...rix.com>
Subject: Re: [PATCH v2 06/20] block/xen-blkfront: Store a page rather a pfn
in the grant structure
On Thu, 9 Jul 2015, Julien Grall wrote:
> All the usage of the field pfn are done using the same idiom:
>
> pfn_to_page(grant->pfn)
>
> This will return always the same page. Store directly the page in the
> grant to clean up the code.
>
> Signed-off-by: Julien Grall <julien.grall@...rix.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Cc: Roger Pau Monné <roger.pau@...rix.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: David Vrabel <david.vrabel@...rix.com>
> ---
> Changes in v2:
> - Patch added
> ---
> drivers/block/xen-blkfront.c | 37 ++++++++++++++++++-------------------
> 1 file changed, 18 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 7107d58..7b81d23 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -67,7 +67,7 @@ enum blkif_state {
>
> struct grant {
> grant_ref_t gref;
> - unsigned long pfn;
> + struct page *page;
> struct list_head node;
> };
>
> @@ -219,7 +219,7 @@ static int fill_grant_buffer(struct blkfront_info *info, int num)
> kfree(gnt_list_entry);
> goto out_of_memory;
> }
> - gnt_list_entry->pfn = page_to_pfn(granted_page);
> + gnt_list_entry->page = granted_page;
> }
>
> gnt_list_entry->gref = GRANT_INVALID_REF;
> @@ -234,7 +234,7 @@ out_of_memory:
> &info->grants, node) {
> list_del(&gnt_list_entry->node);
> if (info->feature_persistent)
> - __free_page(pfn_to_page(gnt_list_entry->pfn));
> + __free_page(gnt_list_entry->page);
> kfree(gnt_list_entry);
> i--;
> }
> @@ -243,7 +243,7 @@ out_of_memory:
> }
>
> static struct grant *get_grant(grant_ref_t *gref_head,
> - unsigned long pfn,
> + struct page *page,
> struct blkfront_info *info)
indentation
Aside from this:
Reviewed-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> {
> struct grant *gnt_list_entry;
> @@ -263,10 +263,10 @@ static struct grant *get_grant(grant_ref_t *gref_head,
> gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
> BUG_ON(gnt_list_entry->gref == -ENOSPC);
> if (!info->feature_persistent) {
> - BUG_ON(!pfn);
> - gnt_list_entry->pfn = pfn;
> + BUG_ON(!page);
> + gnt_list_entry->page = page;
> }
> - buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
> + buffer_mfn = page_to_mfn(gnt_list_entry->page);
> gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
> info->xbdev->otherend_id,
> buffer_mfn, 0);
> @@ -522,7 +522,7 @@ static int blkif_queue_rw_req(struct request *req)
>
> if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
> (i % SEGS_PER_INDIRECT_FRAME == 0)) {
> - unsigned long uninitialized_var(pfn);
> + struct page *uninitialized_var(page);
>
> if (segments)
> kunmap_atomic(segments);
> @@ -536,15 +536,15 @@ static int blkif_queue_rw_req(struct request *req)
> indirect_page = list_first_entry(&info->indirect_pages,
> struct page, lru);
> list_del(&indirect_page->lru);
> - pfn = page_to_pfn(indirect_page);
> + page = indirect_page;
> }
> - gnt_list_entry = get_grant(&gref_head, pfn, info);
> + gnt_list_entry = get_grant(&gref_head, page, info);
> info->shadow[id].indirect_grants[n] = gnt_list_entry;
> - segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
> + segments = kmap_atomic(gnt_list_entry->page);
> ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
> }
>
> - gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
> + gnt_list_entry = get_grant(&gref_head, sg_page(sg), info);
> ref = gnt_list_entry->gref;
>
> info->shadow[id].grants_used[i] = gnt_list_entry;
> @@ -555,7 +555,7 @@ static int blkif_queue_rw_req(struct request *req)
>
> BUG_ON(sg->offset + sg->length > PAGE_SIZE);
>
> - shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
> + shared_data = kmap_atomic(gnt_list_entry->page);
> bvec_data = kmap_atomic(sg_page(sg));
>
> /*
> @@ -1002,7 +1002,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> info->persistent_gnts_c--;
> }
> if (info->feature_persistent)
> - __free_page(pfn_to_page(persistent_gnt->pfn));
> + __free_page(persistent_gnt->page);
> kfree(persistent_gnt);
> }
> }
> @@ -1037,7 +1037,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> persistent_gnt = info->shadow[i].grants_used[j];
> gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
> if (info->feature_persistent)
> - __free_page(pfn_to_page(persistent_gnt->pfn));
> + __free_page(persistent_gnt->page);
> kfree(persistent_gnt);
> }
>
> @@ -1051,7 +1051,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> for (j = 0; j < INDIRECT_GREFS(segs); j++) {
> persistent_gnt = info->shadow[i].indirect_grants[j];
> gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
> - __free_page(pfn_to_page(persistent_gnt->pfn));
> + __free_page(persistent_gnt->page);
> kfree(persistent_gnt);
> }
>
> @@ -1102,8 +1102,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
> if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
> for_each_sg(s->sg, sg, nseg, i) {
> BUG_ON(sg->offset + sg->length > PAGE_SIZE);
> - shared_data = kmap_atomic(
> - pfn_to_page(s->grants_used[i]->pfn));
> + shared_data = kmap_atomic(s->grants_used[i]->page);
> bvec_data = kmap_atomic(sg_page(sg));
> memcpy(bvec_data + sg->offset,
> shared_data + sg->offset,
> @@ -1154,7 +1153,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
> * Add the used indirect page back to the list of
> * available pages for indirect grefs.
> */
> - indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
> + indirect_page = s->indirect_grants[i]->page;
> list_add(&indirect_page->lru, &info->indirect_pages);
> s->indirect_grants[i]->gref = GRANT_INVALID_REF;
> list_add_tail(&s->indirect_grants[i]->node, &info->grants);
> --
> 2.1.4
>
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