[Devel] [PATCH VZ9 v3 07/13] dm-ploop: speed up ploop_prepare_bat_update()

[Andrey Zhadchenko]

Drop ploop_cluster_is_in_top_delta(), because
 - it internally searches md on every call
 - it takes read lock every time

https://virtuozzo.atlassian.net/browse/VSTOR-91817
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index b160dd00e497..76d344a7bcad 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -885,13 +885,14 @@ static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
 static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 				    enum piwb_type type)
 {
-	u32 i, off, last, *bat_entries;
+	u32 i, off, last, *bat_entries, clu;
 	struct ploop_index_wb *piwb;
 	bool is_last_page = true;
 	u32 page_id = md->id;
 	struct page *page;
 	struct pio *pio;
 	map_index_t *to;
+	u8 level;
 
 	piwb = kmalloc(sizeof(*piwb), GFP_NOIO);
 	if (!piwb)
@@ -914,6 +915,8 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 
 	piwb->page_id = page_id;
 	to = piwb->kmpage;
+
+	read_lock_irq(&md->lock);
 	memcpy((void *)to, bat_entries, PAGE_SIZE);
 
 	/* Absolute number of first index in page (negative for page#0) */
@@ -932,10 +935,14 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 
 	/* Copy BAT (BAT goes right after hdr, see .ctr) */
 	for (; i < last; i++) {
-		if (ploop_cluster_is_in_top_delta(ploop, i + off))
-			continue;
-		to[i] = 0;
+		level = md->bat_levels[i];
+		clu = READ_ONCE(bat_entries[i]);
+
+		if (clu == BAT_ENTRY_NONE || level < ploop_top_level(ploop))
+			to[i] = 0;
 	}
+	read_unlock_irq(&md->lock);
+
 	if (is_last_page) {
 	/* Fill tail of page with 0 */
 		for (i = last; i < PAGE_SIZE / sizeof(map_index_t); i++)
-- 
2.39.3