[PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if huge page cache enabled

[Kirill A. Shutemov]

We are going to do IO a huge page a time. So we need BIO_MAX_PAGES to be
at least HPAGE_PMD_NR. For x86-64, it's 512 pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 block/bio.c         | 3 ++-
 include/linux/bio.h | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index db85c5753a76..a69062bda3e0 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -44,7 +44,8 @@
  */
 #define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
 static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
-	BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
+	BV(1), BV(4), BV(16), BV(64), BV(128),
+	{ .nr_vecs = BIO_MAX_PAGES, .name ="biovec-max_pages" },
 };
 #undef BV
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 97cb48f03dc7..19d0fae9cdd0 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -38,7 +38,11 @@
 #define BIO_BUG_ON
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
+#define BIO_MAX_PAGES		(HPAGE_PMD_NR > 256 ? HPAGE_PMD_NR : 256)
+#else
 #define BIO_MAX_PAGES		256
+#endif
 
 #define bio_prio(bio)			(bio)->bi_ioprio
 #define bio_set_prio(bio, prio)		((bio)->bi_ioprio = prio)
-- 
2.9.3