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authorYufen Yu <yuyufen@huawei.com>2020-08-20 09:22:12 -0400
committerSong Liu <songliubraving@fb.com>2020-09-24 16:44:44 -0700
commit046169f048cdea84fd327469239e2dfa317981b5 (patch)
tree7b83d9a3f31c6f5d4cc2ef646e5c6545c75bc020 /drivers/md/raid5.h
parent4f86ff5580fa692f850f37f948c73814a24a722b (diff)
downloadlinux-046169f048cdea84fd327469239e2dfa317981b5.tar.bz2
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.h')
-rw-r--r--drivers/md/raid5.h28
1 files changed, 27 insertions, 1 deletions
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 6afdd3a78580..5c05acf20e1f 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -195,6 +195,7 @@ enum reconstruct_states {
reconstruct_state_result,
};
+#define DEFAULT_STRIPE_SIZE 4096
struct stripe_head {
struct hlist_node hash;
struct list_head lru; /* inactive_list or handle_list */
@@ -246,6 +247,13 @@ struct stripe_head {
int target, target2;
enum sum_check_flags zero_sum_result;
} ops;
+
+#if PAGE_SIZE != DEFAULT_STRIPE_SIZE
+ /* These pages will be used by bios in dev[i] */
+ struct page **pages;
+ int nr_pages; /* page array size */
+ int stripes_per_page;
+#endif
struct r5dev {
/* rreq and rvec are used for the replacement device when
* writing data to both devices.
@@ -473,7 +481,6 @@ struct disk_info {
*/
#define NR_STRIPES 256
-#define DEFAULT_STRIPE_SIZE 4096
#if PAGE_SIZE == DEFAULT_STRIPE_SIZE
#define STRIPE_SIZE PAGE_SIZE
@@ -772,6 +779,25 @@ static inline int algorithm_is_DDF(int layout)
return layout >= 8 && layout <= 10;
}
+#if PAGE_SIZE != DEFAULT_STRIPE_SIZE
+/*
+ * Return offset of the corresponding page for r5dev.
+ */
+static inline int raid5_get_page_offset(struct stripe_head *sh, int disk_idx)
+{
+ return (disk_idx % sh->stripes_per_page) * RAID5_STRIPE_SIZE(sh->raid_conf);
+}
+
+/*
+ * Return corresponding page address for r5dev.
+ */
+static inline struct page *
+raid5_get_dev_page(struct stripe_head *sh, int disk_idx)
+{
+ return sh->pages[disk_idx / sh->stripes_per_page];
+}
+#endif
+
extern void md_raid5_kick_device(struct r5conf *conf);
extern int raid5_set_cache_size(struct mddev *mddev, int size);
extern sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous);