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authorYufen Yu <yuyufen@huawei.com>2020-08-20 16:22:12 +0300
committerSong Liu <songliubraving@fb.com>2020-09-25 02:44:44 +0300
commit046169f048cdea84fd327469239e2dfa317981b5 (patch)
tree7b83d9a3f31c6f5d4cc2ef646e5c6545c75bc020 /drivers/md/raid5.c
parent4f86ff5580fa692f850f37f948c73814a24a722b (diff)
downloadlinux-046169f048cdea84fd327469239e2dfa317981b5.tar.xz
md/raid5: let multiple devices of stripe_head share page
In current implementation, grow_buffers() uses alloc_page() to allocate the buffers for each stripe_head, i.e. allocate a page for each dev[i] in stripe_head. After setting stripe_size as a configurable value by writing sysfs entry, it means that we always allocate 64K buffers, but just use 4K of them when stripe_size is 4K in 64KB arm64. To avoid wasting memory, we try to let multiple sh->dev share one real page. That means, multiple sh->dev[i].page will point to the only page with different offset. Example of 64K PAGE_SIZE and 4K stripe_size as following: 64K PAGE_SIZE +---+---+---+---+------------------------------+ | | | | | | | | | | +-+-+-+-+-+-+-+-+------------------------------+ ^ ^ ^ ^ | | | +----------------------------+ | | | | | | +-------------------+ | | | | | | +----------+ | | | | | | +-+ | | | | | | | +-----+-----+------+-----+------+-----+------+------+ sh | offset(0) | offset(4K) | offset(8K) | offset(12K) | + +-----------+------------+------------+-------------+ +----> dev[0].page dev[1].page dev[2].page dev[3].page A new 'pages' array will be added into stripe_head to record shared page used by this stripe_head. Allocate them when grow_buffers() and free them when shrink_buffers(). After trying to share page, the users of sh->dev[i].page need to take care of the related page offset: page of issued bio and page passed to xor compution functions. But thanks for previous different page offset supported. Here, we just need to set correct dev[i].offset. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Song Liu <songliubraving@fb.com>
Diffstat (limited to 'drivers/md/raid5.c')
-rw-r--r--drivers/md/raid5.c89
1 files changed, 87 insertions, 2 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d36b8192940b..ea1e56e21a31 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -448,13 +448,74 @@ out:
return sh;
}
-static void shrink_buffers(struct stripe_head *sh)
+#if PAGE_SIZE != DEFAULT_STRIPE_SIZE
+static void free_stripe_pages(struct stripe_head *sh)
+{
+ int i;
+ struct page *p;
+
+ /* Have not allocate page pool */
+ if (!sh->pages)
+ return;
+
+ for (i = 0; i < sh->nr_pages; i++) {
+ p = sh->pages[i];
+ if (p)
+ put_page(p);
+ sh->pages[i] = NULL;
+ }
+}
+
+static int alloc_stripe_pages(struct stripe_head *sh, gfp_t gfp)
{
+ int i;
struct page *p;
+
+ for (i = 0; i < sh->nr_pages; i++) {
+ /* The page have allocated. */
+ if (sh->pages[i])
+ continue;
+
+ p = alloc_page(gfp);
+ if (!p) {
+ free_stripe_pages(sh);
+ return -ENOMEM;
+ }
+ sh->pages[i] = p;
+ }
+ return 0;
+}
+
+static int
+init_stripe_shared_pages(struct stripe_head *sh, struct r5conf *conf, int disks)
+{
+ int nr_pages, cnt;
+
+ if (sh->pages)
+ return 0;
+
+ /* Each of the sh->dev[i] need one conf->stripe_size */
+ cnt = PAGE_SIZE / conf->stripe_size;
+ nr_pages = (disks + cnt - 1) / cnt;
+
+ sh->pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
+ if (!sh->pages)
+ return -ENOMEM;
+ sh->nr_pages = nr_pages;
+ sh->stripes_per_page = cnt;
+ return 0;
+}
+#endif
+
+static void shrink_buffers(struct stripe_head *sh)
+{
int i;
int num = sh->raid_conf->pool_size;
+#if PAGE_SIZE == DEFAULT_STRIPE_SIZE
for (i = 0; i < num ; i++) {
+ struct page *p;
+
WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
p = sh->dev[i].page;
if (!p)
@@ -462,6 +523,11 @@ static void shrink_buffers(struct stripe_head *sh)
sh->dev[i].page = NULL;
put_page(p);
}
+#else
+ for (i = 0; i < num; i++)
+ sh->dev[i].page = NULL;
+ free_stripe_pages(sh); /* Free pages */
+#endif
}
static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
@@ -469,6 +535,7 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
int i;
int num = sh->raid_conf->pool_size;
+#if PAGE_SIZE == DEFAULT_STRIPE_SIZE
for (i = 0; i < num; i++) {
struct page *page;
@@ -479,7 +546,16 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
sh->dev[i].orig_page = page;
sh->dev[i].offset = 0;
}
+#else
+ if (alloc_stripe_pages(sh, gfp))
+ return -ENOMEM;
+ for (i = 0; i < num; i++) {
+ sh->dev[i].page = raid5_get_dev_page(sh, i);
+ sh->dev[i].orig_page = sh->dev[i].page;
+ sh->dev[i].offset = raid5_get_page_offset(sh, i);
+ }
+#endif
return 0;
}
@@ -2205,6 +2281,9 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
static void free_stripe(struct kmem_cache *sc, struct stripe_head *sh)
{
+#if PAGE_SIZE != DEFAULT_STRIPE_SIZE
+ kfree(sh->pages);
+#endif
if (sh->ppl_page)
__free_page(sh->ppl_page);
kmem_cache_free(sc, sh);
@@ -2238,9 +2317,15 @@ static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
sh->ppl_page = alloc_page(gfp);
if (!sh->ppl_page) {
free_stripe(sc, sh);
- sh = NULL;
+ return NULL;
}
}
+#if PAGE_SIZE != DEFAULT_STRIPE_SIZE
+ if (init_stripe_shared_pages(sh, conf, disks)) {
+ free_stripe(sc, sh);
+ return NULL;
+ }
+#endif
}
return sh;
}