[PATCH] drivers: xen-blkback: delay pending_req allocation to connect_ring
From: Bob Liu
Date: Mon May 25 2015 - 20:06:33 EST
In connect_ring, we can know exactly how many pages are used for the shared
ring and also whether feature-persistent is enabled, delay pending_req
allocation here so that we won't waste too much memory.
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
drivers/block/xen-blkback/common.h | 3 +-
drivers/block/xen-blkback/xenbus.c | 95 ++++++++++++++++++++------------------
2 files changed, 51 insertions(+), 47 deletions(-)
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 919a1ab..e1d605d 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -249,7 +249,7 @@ struct backend_info;
#define PERSISTENT_GNT_WAS_ACTIVE 1
/* Number of requests that we can fit in a ring */
-#define XEN_MAX_BLKIF_REQS (32 * XENBUS_MAX_RING_PAGES)
+#define XEN_BLKIF_REQS 32
struct persistent_gnt {
struct page *page;
@@ -321,6 +321,7 @@ struct xen_blkif {
struct work_struct free_work;
/* Thread shutdown wait queue. */
wait_queue_head_t shutdown_wq;
+ unsigned int nr_ring_pages;
};
struct seg_buf {
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index bc33888..48336a3 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -125,8 +125,6 @@ static void xen_update_blkif_status(struct xen_blkif *blkif)
static struct xen_blkif *xen_blkif_alloc(domid_t domid)
{
struct xen_blkif *blkif;
- struct pending_req *req, *n;
- int i, j;
BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
@@ -153,50 +151,11 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
INIT_LIST_HEAD(&blkif->pending_free);
INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
- for (i = 0; i < XEN_MAX_BLKIF_REQS; i++) {
- req = kzalloc(sizeof(*req), GFP_KERNEL);
- if (!req)
- goto fail;
- list_add_tail(&req->free_list,
- &blkif->pending_free);
- for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
- req->segments[j] = kzalloc(sizeof(*req->segments[0]),
- GFP_KERNEL);
- if (!req->segments[j])
- goto fail;
- }
- for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
- req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
- GFP_KERNEL);
- if (!req->indirect_pages[j])
- goto fail;
- }
- }
spin_lock_init(&blkif->pending_free_lock);
init_waitqueue_head(&blkif->pending_free_wq);
init_waitqueue_head(&blkif->shutdown_wq);
return blkif;
-
-fail:
- list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
- list_del(&req->free_list);
- for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
- if (!req->segments[j])
- break;
- kfree(req->segments[j]);
- }
- for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
- if (!req->indirect_pages[j])
- break;
- kfree(req->indirect_pages[j]);
- }
- kfree(req);
- }
-
- kmem_cache_free(xen_blkif_cachep, blkif);
-
- return ERR_PTR(-ENOMEM);
}
static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
@@ -313,7 +272,7 @@ static void xen_blkif_free(struct xen_blkif *blkif)
i++;
}
- WARN_ON(i != XEN_MAX_BLKIF_REQS);
+ WARN_ON(i != XEN_BLKIF_REQS * blkif->nr_ring_pages);
kmem_cache_free(xen_blkif_cachep, blkif);
}
@@ -868,9 +827,10 @@ static int connect_ring(struct backend_info *be)
struct xenbus_device *dev = be->dev;
unsigned int ring_ref[XENBUS_MAX_RING_PAGES];
unsigned int evtchn, nr_grefs, ring_page_order;
- unsigned int pers_grants;
+ unsigned int pers_grants, i, j;
+ struct pending_req *req, *n;
char protocol[64] = "";
- int err;
+ int err, nr_indiret_pages, nr_segs;
pr_debug("%s %s\n", __func__, dev->otherend);
@@ -899,8 +859,6 @@ static int connect_ring(struct backend_info *be)
pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
ring_ref[0]);
} else {
- unsigned int i;
-
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
@@ -949,11 +907,39 @@ static int connect_ring(struct backend_info *be)
be->blkif->vbd.feature_gnt_persistent = pers_grants;
be->blkif->vbd.overflow_max_grants = 0;
+ be->blkif->nr_ring_pages = nr_grefs;
pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
pers_grants ? "persistent grants" : "");
+ if (!pers_grants) {
+ nr_indiret_pages = 0;
+ nr_segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
+ } else {
+ nr_indiret_pages = MAX_INDIRECT_PAGES;
+ nr_segs = MAX_INDIRECT_SEGMENTS;
+ }
+
+ for (i = 0; i < nr_grefs * XEN_BLKIF_REQS; i++) {
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ goto fail;
+ list_add_tail(&req->free_list, &be->blkif->pending_free);
+ for (j = 0; j < nr_segs; j++) {
+ req->segments[j] = kzalloc(sizeof(*req->segments[0]),
+ GFP_KERNEL);
+ if (!req->segments[j])
+ goto fail;
+ }
+ for (j = 0; j < nr_indiret_pages; j++) {
+ req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
+ GFP_KERNEL);
+ if (!req->indirect_pages[j])
+ goto fail;
+ }
+ }
+
/* Map the shared frame, irq etc. */
err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
if (err) {
@@ -962,6 +948,23 @@ static int connect_ring(struct backend_info *be)
}
return 0;
+
+fail:
+ list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) {
+ list_del(&req->free_list);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
+ if (!req->segments[j])
+ break;
+ kfree(req->segments[j]);
+ }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
+ if (!req->indirect_pages[j])
+ break;
+ kfree(req->indirect_pages[j]);
+ }
+ kfree(req);
+ }
+ return -ENOMEM;
}
static const struct xenbus_device_id xen_blkbk_ids[] = {
--
1.8.3.1
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