Btrfs: cache values for locking extents

Many of the btrfs extent state tree users follow the same pattern.
They lock an extent range in the tree, do some operation and then
unlock.

This translates to at least 2 rbtree searches, and maybe more if they
are doing operations on the extent state tree.  A locked extent
in the tree isn't going to be merged or changed, and so we can
safely return the extent state structure as a cached handle.

This changes set_extent_bit to give back a cached handle, and also
changes both set_extent_bit and clear_extent_bit to use the cached
handle if it is available.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f1df11718618..e494545c4202 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -854,7 +854,7 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
         int limit = 10 * 1024 * 1042;
 
         clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED |
-                         EXTENT_DELALLOC, 1, 0, GFP_NOFS);
+                         EXTENT_DELALLOC, 1, 0, NULL, GFP_NOFS);
         while (start < end) {
                 async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
                 async_cow->inode = inode;
@@ -4420,7 +4420,7 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
                  */
                 clear_extent_bit(tree, page_start, page_end,
                                  EXTENT_DIRTY | EXTENT_DELALLOC |
-                                 EXTENT_LOCKED, 1, 0, GFP_NOFS);
+                                 EXTENT_LOCKED, 1, 0, NULL, GFP_NOFS);
                 btrfs_finish_ordered_io(page->mapping->host,
                                         page_start, page_end);
                 btrfs_put_ordered_extent(ordered);
@@ -4429,7 +4429,7 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
         clear_extent_bit(tree, page_start, page_end,
                  EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
                  EXTENT_ORDERED,
-                 1, 1, GFP_NOFS);
+                 1, 1, NULL, GFP_NOFS);
         __btrfs_releasepage(page, GFP_NOFS);
 
         ClearPageChecked(page);