Btrfs: extent_io and extent_state optimizations

The end_bio routines are changed to take a pointer to the extent state
struct, and the state tree is walked in order to set/clear appropriate
bits as IO completes.  This greatly reduces the number of rbtree searches
done by the end_bio handlers, and reduces lock contention.

The extent_io releasepage function is changed to avoid expensive searches
for locked state.

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

1 files changed, 23 insertions, 12 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 484551274100..bac8722e14e1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -331,7 +331,8 @@ out:
         return ret;
 }
 
-int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
+int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
+                               struct extent_state *state)
 {
         size_t offset = start - ((u64)page->index << PAGE_CACHE_SHIFT);
         struct inode *inode = page->mapping->host;
@@ -347,7 +348,12 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
             btrfs_test_flag(inode, NODATASUM))
                 return 0;
 
-        ret = get_state_private(io_tree, start, &private);
+        if (state->start == start) {
+                private = state->private;
+                ret = 0;
+        } else {
+                ret = get_state_private(io_tree, start, &private);
+        }
         local_irq_save(flags);
         kaddr = kmap_atomic(page, KM_IRQ0);
         if (ret) {
@@ -1830,7 +1836,7 @@ out_unlock:
 }
 
 struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
-                                    size_t page_offset, u64 start, u64 len,
+                                    size_t pg_offset, u64 start, u64 len,
                                     int create)
 {
         int ret;
@@ -1865,7 +1871,10 @@ again:
                                start, len, em->start, em->len);
                         WARN_ON(1);
                 }
-                goto out;
+                if (em->block_start == EXTENT_MAP_INLINE && page)
+                        free_extent_map(em);
+                else
+                        goto out;
         }
         em = alloc_extent_map(GFP_NOFS);
         if (!em) {
@@ -1930,6 +1939,7 @@ again:
                 em->len = extent_end - extent_start;
                 goto insert;
         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+                u64 page_start;
                 unsigned long ptr;
                 char *map;
                 size_t size;
@@ -1959,16 +1969,17 @@ again:
                         goto out;
                 }
 
-                extent_offset = ((u64)page->index << PAGE_CACHE_SHIFT) -
-                        extent_start + page_offset;
-                copy_size = min_t(u64, PAGE_CACHE_SIZE - page_offset,
+                page_start = page_offset(page) + pg_offset;
+                extent_offset = page_start - extent_start;
+                copy_size = min_t(u64, PAGE_CACHE_SIZE - pg_offset,
                                 size - extent_offset);
                 em->start = extent_start + extent_offset;
-                em->len = copy_size;
+                em->len = (copy_size + root->sectorsize - 1) &
+                        ~((u64)root->sectorsize - 1);
                 map = kmap(page);
                 ptr = btrfs_file_extent_inline_start(item) + extent_offset;
                 if (create == 0 && !PageUptodate(page)) {
-                        read_extent_buffer(leaf, map + page_offset, ptr,
+                        read_extent_buffer(leaf, map + pg_offset, ptr,
                                            copy_size);
                         flush_dcache_page(page);
                 } else if (create && PageUptodate(page)) {
@@ -1980,7 +1991,7 @@ again:
                                 trans = btrfs_start_transaction(root, 1);
                                 goto again;
                         }
-                        write_extent_buffer(leaf, map + page_offset, ptr,
+                        write_extent_buffer(leaf, map + pg_offset, ptr,
                                             copy_size);
                         btrfs_mark_buffer_dirty(leaf);
                 }
@@ -2077,7 +2088,7 @@ btrfs_readpages(struct file *file, struct address_space *mapping,
                                 btrfs_get_extent);
 }
 
-static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
+static int btrfs_releasepage(struct page *page, gfp_t gfp_flags)
 {
         struct extent_io_tree *tree;
         struct extent_map_tree *map;
@@ -2085,7 +2096,7 @@ static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 
         tree = &BTRFS_I(page->mapping->host)->io_tree;
         map = &BTRFS_I(page->mapping->host)->extent_tree;
-        ret = try_release_extent_mapping(map, tree, page);
+        ret = try_release_extent_mapping(map, tree, page, gfp_flags);
         if (ret == 1) {
                 ClearPagePrivate(page);
                 set_page_private(page, 0);