From bfe11d6de1c416cea4f3f0f35f864162063ce3fa Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Tue, 29 Oct 2013 18:31:14 +0100 Subject: [PATCH] xen-blkfront: restore the non-persistent data path MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When persistent grants were added they were always used, even if the backend doesn't have this feature (there's no harm in always using the same set of pages). This restores the old data path when the backend doesn't have persistent grants, removing the burden of doing a memcpy when it is not actually needed. Signed-off-by: Roger Pau Monné Reported-by: Felipe Franciosi Cc: Felipe Franciosi Cc: Konrad Rzeszutek Wilk Cc: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk [v2: Fix up whitespace issues] --- drivers/block/xen-blkfront.c | 125 ++++++++++++++++++++++++++++------- 1 file changed, 100 insertions(+), 25 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 5b8a15483a4c..432db1b59b00 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -121,7 +121,8 @@ struct blkfront_info struct work_struct work; struct gnttab_free_callback callback; struct blk_shadow shadow[BLK_RING_SIZE]; - struct list_head persistent_gnts; + struct list_head grants; + struct list_head indirect_pages; unsigned int persistent_gnts_c; unsigned long shadow_free; unsigned int feature_flush; @@ -200,15 +201,17 @@ static int fill_grant_buffer(struct blkfront_info *info, int num) if (!gnt_list_entry) goto out_of_memory; - granted_page = alloc_page(GFP_NOIO); - if (!granted_page) { - kfree(gnt_list_entry); - goto out_of_memory; + if (info->feature_persistent) { + granted_page = alloc_page(GFP_NOIO); + if (!granted_page) { + kfree(gnt_list_entry); + goto out_of_memory; + } + gnt_list_entry->pfn = page_to_pfn(granted_page); } - gnt_list_entry->pfn = page_to_pfn(granted_page); gnt_list_entry->gref = GRANT_INVALID_REF; - list_add(&gnt_list_entry->node, &info->persistent_gnts); + list_add(&gnt_list_entry->node, &info->grants); i++; } @@ -216,9 +219,10 @@ static int fill_grant_buffer(struct blkfront_info *info, int num) out_of_memory: list_for_each_entry_safe(gnt_list_entry, n, - &info->persistent_gnts, node) { + &info->grants, node) { list_del(&gnt_list_entry->node); - __free_page(pfn_to_page(gnt_list_entry->pfn)); + if (info->feature_persistent) + __free_page(pfn_to_page(gnt_list_entry->pfn)); kfree(gnt_list_entry); i--; } @@ -227,13 +231,14 @@ out_of_memory: } static struct grant *get_grant(grant_ref_t *gref_head, + unsigned long pfn, struct blkfront_info *info) { struct grant *gnt_list_entry; unsigned long buffer_mfn; - BUG_ON(list_empty(&info->persistent_gnts)); - gnt_list_entry = list_first_entry(&info->persistent_gnts, struct grant, + BUG_ON(list_empty(&info->grants)); + gnt_list_entry = list_first_entry(&info->grants, struct grant, node); list_del(&gnt_list_entry->node); @@ -245,6 +250,10 @@ static struct grant *get_grant(grant_ref_t *gref_head, /* Assign a gref to this page */ 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; + } buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); gnttab_grant_foreign_access_ref(gnt_list_entry->gref, info->xbdev->otherend_id, @@ -480,22 +489,34 @@ static int blkif_queue_request(struct request *req) if ((ring_req->operation == BLKIF_OP_INDIRECT) && (i % SEGS_PER_INDIRECT_FRAME == 0)) { + unsigned long pfn; + if (segments) kunmap_atomic(segments); n = i / SEGS_PER_INDIRECT_FRAME; - gnt_list_entry = get_grant(&gref_head, info); + if (!info->feature_persistent) { + struct page *indirect_page; + + /* Fetch a pre-allocated page to use for indirect grefs */ + BUG_ON(list_empty(&info->indirect_pages)); + indirect_page = list_first_entry(&info->indirect_pages, + struct page, lru); + list_del(&indirect_page->lru); + pfn = page_to_pfn(indirect_page); + } + gnt_list_entry = get_grant(&gref_head, pfn, info); info->shadow[id].indirect_grants[n] = gnt_list_entry; segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; } - gnt_list_entry = get_grant(&gref_head, info); + gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); ref = gnt_list_entry->gref; info->shadow[id].grants_used[i] = gnt_list_entry; - if (rq_data_dir(req)) { + if (rq_data_dir(req) && info->feature_persistent) { char *bvec_data; void *shared_data; @@ -907,21 +928,36 @@ static void blkif_free(struct blkfront_info *info, int suspend) blk_stop_queue(info->rq); /* Remove all persistent grants */ - if (!list_empty(&info->persistent_gnts)) { + if (!list_empty(&info->grants)) { list_for_each_entry_safe(persistent_gnt, n, - &info->persistent_gnts, node) { + &info->grants, node) { list_del(&persistent_gnt->node); if (persistent_gnt->gref != GRANT_INVALID_REF) { gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); info->persistent_gnts_c--; } - __free_page(pfn_to_page(persistent_gnt->pfn)); + if (info->feature_persistent) + __free_page(pfn_to_page(persistent_gnt->pfn)); kfree(persistent_gnt); } } BUG_ON(info->persistent_gnts_c != 0); + /* + * Remove indirect pages, this only happens when using indirect + * descriptors but not persistent grants + */ + if (!list_empty(&info->indirect_pages)) { + struct page *indirect_page, *n; + + BUG_ON(info->feature_persistent); + list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { + list_del(&indirect_page->lru); + __free_page(indirect_page); + } + } + for (i = 0; i < BLK_RING_SIZE; i++) { /* * Clear persistent grants present in requests already @@ -936,7 +972,8 @@ static void blkif_free(struct blkfront_info *info, int suspend) for (j = 0; j < segs; j++) { persistent_gnt = info->shadow[i].grants_used[j]; gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); - __free_page(pfn_to_page(persistent_gnt->pfn)); + if (info->feature_persistent) + __free_page(pfn_to_page(persistent_gnt->pfn)); kfree(persistent_gnt); } @@ -995,7 +1032,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, nseg = s->req.operation == BLKIF_OP_INDIRECT ? s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; - if (bret->operation == BLKIF_OP_READ) { + if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { /* * Copy the data received from the backend into the bvec. * Since bv_offset can be different than 0, and bv_len different @@ -1023,7 +1060,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, * we add it at the head of the list, so it will be * reused first. */ - list_add(&s->grants_used[i]->node, &info->persistent_gnts); + if (!info->feature_persistent) + pr_alert_ratelimited("backed has not unmapped grant: %u\n", + s->grants_used[i]->gref); + list_add(&s->grants_used[i]->node, &info->grants); info->persistent_gnts_c++; } else { /* @@ -1034,19 +1074,29 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, */ gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); s->grants_used[i]->gref = GRANT_INVALID_REF; - list_add_tail(&s->grants_used[i]->node, &info->persistent_gnts); + list_add_tail(&s->grants_used[i]->node, &info->grants); } } if (s->req.operation == BLKIF_OP_INDIRECT) { for (i = 0; i < INDIRECT_GREFS(nseg); i++) { if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { - list_add(&s->indirect_grants[i]->node, &info->persistent_gnts); + if (!info->feature_persistent) + pr_alert_ratelimited("backed has not unmapped grant: %u\n", + s->indirect_grants[i]->gref); + list_add(&s->indirect_grants[i]->node, &info->grants); info->persistent_gnts_c++; } else { + struct page *indirect_page; + gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); + /* + * 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); + 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->persistent_gnts); + list_add_tail(&s->indirect_grants[i]->node, &info->grants); } } } @@ -1341,7 +1391,8 @@ static int blkfront_probe(struct xenbus_device *dev, spin_lock_init(&info->io_lock); info->xbdev = dev; info->vdevice = vdevice; - INIT_LIST_HEAD(&info->persistent_gnts); + INIT_LIST_HEAD(&info->grants); + INIT_LIST_HEAD(&info->indirect_pages); info->persistent_gnts_c = 0; info->connected = BLKIF_STATE_DISCONNECTED; INIT_WORK(&info->work, blkif_restart_queue); @@ -1637,6 +1688,23 @@ static int blkfront_setup_indirect(struct blkfront_info *info) if (err) goto out_of_memory; + if (!info->feature_persistent && info->max_indirect_segments) { + /* + * We are using indirect descriptors but not persistent + * grants, we need to allocate a set of pages that can be + * used for mapping indirect grefs + */ + int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; + + BUG_ON(!list_empty(&info->indirect_pages)); + for (i = 0; i < num; i++) { + struct page *indirect_page = alloc_page(GFP_NOIO); + if (!indirect_page) + goto out_of_memory; + list_add(&indirect_page->lru, &info->indirect_pages); + } + } + for (i = 0; i < BLK_RING_SIZE; i++) { info->shadow[i].grants_used = kzalloc( sizeof(info->shadow[i].grants_used[0]) * segs, @@ -1667,6 +1735,13 @@ out_of_memory: kfree(info->shadow[i].indirect_grants); info->shadow[i].indirect_grants = NULL; } + if (!list_empty(&info->indirect_pages)) { + struct page *indirect_page, *n; + list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { + list_del(&indirect_page->lru); + __free_page(indirect_page); + } + } return -ENOMEM; } -- 2.20.1