Btrfs: add the ability to cache a pointer into the eb
This cuts down on the CPU time used by map_private_extent_buffer
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c
index bc1f6ad..c6ffa58 100644
--- a/fs/btrfs/struct-funcs.c
+++ b/fs/btrfs/struct-funcs.c
@@ -44,8 +44,9 @@
#define BTRFS_SETGET_FUNCS(name, type, member, bits) \
u##bits btrfs_##name(struct extent_buffer *eb, type *s); \
void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val); \
-u##bits btrfs_##name(struct extent_buffer *eb, \
- type *s) \
+void btrfs_set_token_##name(struct extent_buffer *eb, type *s, u##bits val, struct btrfs_map_token *token); \
+u##bits btrfs_token_##name(struct extent_buffer *eb, \
+ type *s, struct btrfs_map_token *token) \
{ \
unsigned long part_offset = (unsigned long)s; \
unsigned long offset = part_offset + offsetof(type, member); \
@@ -54,9 +55,18 @@
char *kaddr; \
unsigned long map_start; \
unsigned long map_len; \
+ unsigned long mem_len = sizeof(((type *)0)->member); \
u##bits res; \
+ if (token && token->kaddr && token->offset <= offset && \
+ token->eb == eb && \
+ (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
+ kaddr = token->kaddr; \
+ p = (type *)(kaddr + part_offset - token->offset); \
+ res = le##bits##_to_cpu(p->member); \
+ return res; \
+ } \
err = map_private_extent_buffer(eb, offset, \
- sizeof(((type *)0)->member), \
+ mem_len, \
&kaddr, &map_start, &map_len); \
if (err) { \
__le##bits leres; \
@@ -65,10 +75,15 @@
} \
p = (type *)(kaddr + part_offset - map_start); \
res = le##bits##_to_cpu(p->member); \
+ if (token) { \
+ token->kaddr = kaddr; \
+ token->offset = map_start; \
+ token->eb = eb; \
+ } \
return res; \
} \
-void btrfs_set_##name(struct extent_buffer *eb, \
- type *s, u##bits val) \
+void btrfs_set_token_##name(struct extent_buffer *eb, \
+ type *s, u##bits val, struct btrfs_map_token *token) \
{ \
unsigned long part_offset = (unsigned long)s; \
unsigned long offset = part_offset + offsetof(type, member); \
@@ -77,8 +92,17 @@
char *kaddr; \
unsigned long map_start; \
unsigned long map_len; \
+ unsigned long mem_len = sizeof(((type *)0)->member); \
+ if (token && token->kaddr && token->offset <= offset && \
+ token->eb == eb && \
+ (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
+ kaddr = token->kaddr; \
+ p = (type *)(kaddr + part_offset - token->offset); \
+ p->member = cpu_to_le##bits(val); \
+ return; \
+ } \
err = map_private_extent_buffer(eb, offset, \
- sizeof(((type *)0)->member), \
+ mem_len, \
&kaddr, &map_start, &map_len); \
if (err) { \
__le##bits val2; \
@@ -88,7 +112,22 @@
} \
p = (type *)(kaddr + part_offset - map_start); \
p->member = cpu_to_le##bits(val); \
-}
+ if (token) { \
+ token->kaddr = kaddr; \
+ token->offset = map_start; \
+ token->eb = eb; \
+ } \
+} \
+void btrfs_set_##name(struct extent_buffer *eb, \
+ type *s, u##bits val) \
+{ \
+ btrfs_set_token_##name(eb, s, val, NULL); \
+} \
+u##bits btrfs_##name(struct extent_buffer *eb, \
+ type *s) \
+{ \
+ return btrfs_token_##name(eb, s, NULL); \
+} \
#include "ctree.h"