Btrfs: Cache extent buffer mappings
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 4d05456..54c754d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -436,10 +436,18 @@
unsigned long map_len; \
unsigned long offset = (unsigned long)s + \
offsetof(type, member); \
- err = map_extent_buffer(eb, offset, \
+ if (eb->map_token && offset >= eb->map_start && \
+ offset + sizeof(((type *)0)->member) <= eb->map_start + \
+ eb->map_len) { \
+ kaddr = eb->kaddr; \
+ map_start = eb->map_start; \
+ err = 0; \
+ } else { \
+ err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
+ } \
if (!err) { \
__le##bits *tmp = (__le##bits *)(kaddr + offset - \
map_start); \
@@ -464,10 +472,18 @@
int unmap_on_exit = (eb->map_token == NULL); \
unsigned long offset = (unsigned long)s + \
offsetof(type, member); \
- err = map_extent_buffer(eb, offset, \
+ if (eb->map_token && offset >= eb->map_start && \
+ offset + sizeof(((type *)0)->member) <= eb->map_start + \
+ eb->map_len) { \
+ kaddr = eb->kaddr; \
+ map_start = eb->map_start; \
+ err = 0; \
+ } else { \
+ err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
+ } \
if (!err) { \
__le##bits *tmp = (__le##bits *)(kaddr + offset - \
map_start); \
@@ -490,10 +506,18 @@
unsigned long map_len; \
unsigned long offset = offsetof(type, member); \
int unmap_on_exit = (eb->map_token == NULL); \
- err = map_extent_buffer(eb, offset, \
+ if (eb->map_token && offset >= eb->map_start && \
+ offset + sizeof(((type *)0)->member) <= eb->map_start + \
+ eb->map_len) { \
+ kaddr = eb->kaddr; \
+ map_start = eb->map_start; \
+ err = 0; \
+ } else { \
+ err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
+ } \
if (!err) { \
__le##bits *tmp = (__le##bits *)(kaddr + offset - \
map_start); \
@@ -517,10 +541,18 @@
unsigned long map_len; \
unsigned long offset = offsetof(type, member); \
int unmap_on_exit = (eb->map_token == NULL); \
- err = map_extent_buffer(eb, offset, \
+ if (eb->map_token && offset >= eb->map_start && \
+ offset + sizeof(((type *)0)->member) <= eb->map_start + \
+ eb->map_len) { \
+ kaddr = eb->kaddr; \
+ map_start = eb->map_start; \
+ err = 0; \
+ } else { \
+ err = map_extent_buffer(eb, offset, \
sizeof(((type *)0)->member), \
&map_token, &kaddr, \
&map_start, &map_len, KM_USER1); \
+ } \
if (!err) { \
__le##bits *tmp = (__le##bits *)(kaddr + offset - \
map_start); \