hugetlb: multiple hstates for multiple page sizes

Add basic support for more than one hstate in hugetlbfs.  This is the key
to supporting multiple hugetlbfs page sizes at once.

- Rather than a single hstate, we now have an array, with an iterator
- default_hstate continues to be the struct hstate which we use by default
- Add functions for architectures to register new hstates

[akpm@linux-foundation.org: coding-style fixes]
Acked-by: Adam Litke <agl@us.ibm.com>
Acked-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ad2271e11f9b..b75bdb4deba3 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -36,8 +36,6 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to,
                                                 struct vm_area_struct *vma);
 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
 
-extern unsigned long max_huge_pages;
-extern unsigned long sysctl_overcommit_huge_pages;
 extern unsigned long hugepages_treat_as_movable;
 extern const unsigned long hugetlb_zero, hugetlb_infinity;
 extern int sysctl_hugetlb_shm_group;
@@ -181,7 +179,17 @@ struct hstate {
         unsigned int surplus_huge_pages_node[MAX_NUMNODES];
 };
 
-extern struct hstate default_hstate;
+void __init hugetlb_add_hstate(unsigned order);
+struct hstate *size_to_hstate(unsigned long size);
+
+#ifndef HUGE_MAX_HSTATE
+#define HUGE_MAX_HSTATE 1
+#endif
+
+extern struct hstate hstates[HUGE_MAX_HSTATE];
+extern unsigned int default_hstate_idx;
+
+#define default_hstate (hstates[default_hstate_idx])
 
 static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
 {
@@ -230,6 +238,11 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
 
 #include <asm/hugetlb.h>
 
+static inline struct hstate *page_hstate(struct page *page)
+{
+        return size_to_hstate(PAGE_SIZE << compound_order(page));
+}
+
 #else
 struct hstate {};
 #define hstate_file(f) NULL