Btrfs: extent_map optimizations to cut down on CPU usage

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 14 insertions, 19 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 85b28a6a4e05..f8aaba8a30a2 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1963,9 +1963,9 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb,
         struct page *p;
 
         if (i == 0)
-                return eb->last_page;
+                return eb->first_page;
         i += eb->start >> PAGE_CACHE_SHIFT;
-        p = find_get_page(eb->last_page->mapping, i);
+        p = find_get_page(eb->first_page->mapping, i);
         page_cache_release(p);
         return p;
 }
@@ -2037,7 +2037,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                 }
                 set_page_extent_mapped(p);
                 if (i == 0)
-                        eb->last_page = p;
+                        eb->first_page = p;
                 if (!PageUptodate(p))
                         uptodate = 0;
                 unlock_page(p);
@@ -2083,7 +2083,7 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                 }
                 set_page_extent_mapped(p);
                 if (i == 0)
-                        eb->last_page = p;
+                        eb->first_page = p;
                 if (!PageUptodate(p))
                         uptodate = 0;
                 unlock_page(p);
@@ -2169,7 +2169,15 @@ EXPORT_SYMBOL(wait_on_extent_buffer_writeback);
 int set_extent_buffer_dirty(struct extent_map_tree *tree,
                              struct extent_buffer *eb)
 {
-        return set_range_dirty(tree, eb->start, eb->start + eb->len - 1);
+        unsigned long i;
+        unsigned long num_pages;
+
+        num_pages = num_extent_pages(eb->start, eb->len);
+        for (i = 0; i < num_pages; i++) {
+                __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
+        }
+        return set_extent_dirty(tree, eb->start,
+                                eb->start + eb->len - 1, GFP_NOFS);
 }
 EXPORT_SYMBOL(set_extent_buffer_dirty);
 
@@ -2317,16 +2325,11 @@ static int __map_extent_buffer(struct extent_buffer *eb, unsigned long start,
         size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
         unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
         unsigned long end_i = (start_offset + start + min_len) >>
-                                PAGE_CACHE_SHIFT;
+                PAGE_CACHE_SHIFT;
 
         if (i != end_i)
                 return -EINVAL;
 
-        if (start >= eb->len) {
-                printk("bad start in map eb start %Lu len %lu caller start %lu min %lu\n", eb->start, eb->len, start, min_len);
-                WARN_ON(1);
-        }
-
         if (i == 0) {
                 offset = start_offset;
                 *map_start = 0;
@@ -2353,14 +2356,6 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
         int err;
         int save = 0;
         if (eb->map_token) {
-                if (start >= eb->map_start &&
-                    start + min_len <= eb->map_start + eb->map_len) {
-                        *token = eb->map_token;
-                        *map = eb->kaddr;
-                        *map_start = eb->map_start;
-                        *map_len = eb->map_len;
-                        return 0;
-                }
                 unmap_extent_buffer(eb, eb->map_token, km);
                 eb->map_token = NULL;
                 save = 1;