[PATCH] Btrfs: skip set_page_dirty if eb is dirty

[Liu Bo]

As long as @eb is marked with EXTENT_BUFFER_DIRTY, all of its pages
are dirty, so no need to set pages dirty again.

Signed-off-by: Liu Bo <bo....@linux.alibaba.com>
---
 fs/btrfs/extent_io.c | 11 +++++++----
 fs/btrfs/extent_io.h |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 628f1aef34b0..fb2bf50134a1 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5165,11 +5165,11 @@ void clear_extent_buffer_dirty(struct extent_buffer *eb)
        WARN_ON(atomic_read(&eb->refs) == 0);
 }
 
-int set_extent_buffer_dirty(struct extent_buffer *eb)
+bool set_extent_buffer_dirty(struct extent_buffer *eb)
 {
        int i;
        int num_pages;
-       int was_dirty = 0;
+       bool was_dirty;
 
        check_buffer_tree_ref(eb);
 
@@ -5179,8 +5179,11 @@ int set_extent_buffer_dirty(struct extent_buffer *eb)
        WARN_ON(atomic_read(&eb->refs) == 0);
        WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
 
-       for (i = 0; i < num_pages; i++)
-               set_page_dirty(eb->pages[i]);
+       if (!was_dirty) {
+               for (i = 0; i < num_pages; i++)
+                       set_page_dirty(eb->pages[i]);
+       }
+
        return was_dirty;
 }
 
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index b4d03e677e1d..f2ab42d57f02 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -479,7 +479,7 @@ void extent_buffer_bitmap_set(struct extent_buffer *eb, 
unsigned long start,
 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
                                unsigned long pos, unsigned long len);
 void clear_extent_buffer_dirty(struct extent_buffer *eb);
-int set_extent_buffer_dirty(struct extent_buffer *eb);
+bool set_extent_buffer_dirty(struct extent_buffer *eb);
 void set_extent_buffer_uptodate(struct extent_buffer *eb);
 void clear_extent_buffer_uptodate(struct extent_buffer *eb);
 int extent_buffer_under_io(struct extent_buffer *eb);
-- 
1.8.3.1