[PATCH 5/8] fs,btrfs: Allow kswapd to writeback pages

[Mel Gorman <mel@xxxxxxxxx>]

As only kswapd and memcg are writing back pages, there should be no
danger of overflowing the stack. Allow the writing back of dirty pages
in btrfs from the VM.

Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
---
 fs/btrfs/disk-io.c |   21 +--------------------
 fs/btrfs/inode.c   |    6 ------
 2 files changed, 1 insertions(+), 26 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 34f7c37..e4aa547 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -696,26 +696,7 @@ static int btree_writepage(struct page *page, struct writeback_control *wbc)
 	int was_dirty;
 
 	tree = &BTRFS_I(page->mapping->host)->io_tree;
-	if (!(current->flags & PF_MEMALLOC)) {
-		return extent_write_full_page(tree, page,
-					      btree_get_extent, wbc);
-	}
-
-	redirty_page_for_writepage(wbc, page);
-	eb = btrfs_find_tree_block(root, page_offset(page),
-				      PAGE_CACHE_SIZE);
-	WARN_ON(!eb);
-
-	was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
-	if (!was_dirty) {
-		spin_lock(&root->fs_info->delalloc_lock);
-		root->fs_info->dirty_metadata_bytes += PAGE_CACHE_SIZE;
-		spin_unlock(&root->fs_info->delalloc_lock);
-	}
-	free_extent_buffer(eb);
-
-	unlock_page(page);
-	return 0;
+	return extent_write_full_page(tree, page, btree_get_extent, wbc);
 }
 
 static int btree_writepages(struct address_space *mapping,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1bff92a..5c0e604 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5859,12 +5859,6 @@ static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
 	struct extent_io_tree *tree;
 
-
-	if (current->flags & PF_MEMALLOC) {
-		redirty_page_for_writepage(wbc, page);
-		unlock_page(page);
-		return 0;
-	}
 	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
 }
-- 
1.7.1

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