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authorChris Mason <chris.mason@oracle.com>2011-07-25 06:50:50 -0400
committerChris Mason <chris.mason@oracle.com>2011-07-27 12:46:47 -0400
commit19b6caf4acbf065dc96b47741d99f1b87243c468 (patch)
tree4bce889648c2459e1dbd9fd835a196db26c06f9b /fs
parent31533fb263928c93a34cda41b66a6e83ade5c766 (diff)
downloadop-kernel-dev-19b6caf4acbf065dc96b47741d99f1b87243c468.zip
op-kernel-dev-19b6caf4acbf065dc96b47741d99f1b87243c468.tar.gz
Btrfs: reduce extent_state lock contention for metadata
For metadata buffers that don't straddle pages (all of them), btrfs can safely use the page uptodate bits and extent_buffer uptodate bit instead of needing to use the extent_state tree. This greatly reduces contention on the state tree lock. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/extent_io.c55
1 files changed, 41 insertions, 14 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5392c3b..7b60f62 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3268,6 +3268,22 @@ int set_extent_buffer_dirty(struct extent_io_tree *tree,
return was_dirty;
}
+static int __eb_straddles_pages(u64 start, u64 len)
+{
+ if (len < PAGE_CACHE_SIZE)
+ return 1;
+ if (start & (PAGE_CACHE_SIZE - 1))
+ return 1;
+ if ((start + len) & (PAGE_CACHE_SIZE - 1))
+ return 1;
+ return 0;
+}
+
+static int eb_straddles_pages(struct extent_buffer *eb)
+{
+ return __eb_straddles_pages(eb->start, eb->len);
+}
+
int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
struct extent_buffer *eb,
struct extent_state **cached_state)
@@ -3279,8 +3295,10 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
num_pages = num_extent_pages(eb->start, eb->len);
clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
- clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
- cached_state, GFP_NOFS);
+ if (eb_straddles_pages(eb)) {
+ clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
+ cached_state, GFP_NOFS);
+ }
for (i = 0; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
if (page)
@@ -3298,8 +3316,10 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree,
num_pages = num_extent_pages(eb->start, eb->len);
- set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
- NULL, GFP_NOFS);
+ if (eb_straddles_pages(eb)) {
+ set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
+ NULL, GFP_NOFS);
+ }
for (i = 0; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
@@ -3322,9 +3342,12 @@ int extent_range_uptodate(struct extent_io_tree *tree,
int uptodate;
unsigned long index;
- ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL);
- if (ret)
- return 1;
+ if (__eb_straddles_pages(start, end - start + 1)) {
+ ret = test_range_bit(tree, start, end,
+ EXTENT_UPTODATE, 1, NULL);
+ if (ret)
+ return 1;
+ }
while (start <= end) {
index = start >> PAGE_CACHE_SHIFT;
page = find_get_page(tree->mapping, index);
@@ -3352,10 +3375,12 @@ int extent_buffer_uptodate(struct extent_io_tree *tree,
if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
return 1;
- ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
- EXTENT_UPTODATE, 1, cached_state);
- if (ret)
- return ret;
+ if (eb_straddles_pages(eb)) {
+ ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,
+ EXTENT_UPTODATE, 1, cached_state);
+ if (ret)
+ return ret;
+ }
num_pages = num_extent_pages(eb->start, eb->len);
for (i = 0; i < num_pages; i++) {
@@ -3388,9 +3413,11 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
return 0;
- if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
- EXTENT_UPTODATE, 1, NULL)) {
- return 0;
+ if (eb_straddles_pages(eb)) {
+ if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,
+ EXTENT_UPTODATE, 1, NULL)) {
+ return 0;
+ }
}
if (start) {
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