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Btrfs: add the ability to cache a pointer into the eb

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This cuts down on the CPU time used by map_private_extent_buffer

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2012-03-03 07:40:03 -05:00
parent 0b32f4bbb4
commit cfed81a04e
3 changed files with 116 additions and 30 deletions
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53
fs/btrfs/struct-funcs.c
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@@ -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 @@ u##bits btrfs_##name(struct extent_buffer *eb, \
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 @@ u##bits btrfs_##name(struct extent_buffer *eb, \
} \
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 @@ void btrfs_set_##name(struct extent_buffer *eb, \
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 @@ void btrfs_set_##name(struct extent_buffer *eb, \
} \
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"