fs/mpage.c: factor clean_buffers() out of __mpage_writepage()

__mpage_writepage() is over 200 lines long, has 20 local variables, four
goto labels and could desperately use simplification.  Splitting
clean_buffers() into a helper function improves matters a little,
removing 20+ lines from it.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/mpage.c b/fs/mpage.c
index 4979ffa..4cc9c5d 100644 (file)
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -439,6 +439,35 @@ struct mpage_data {
        unsigned use_writepage;
 };
 
+/*
+ * We have our BIO, so we can now mark the buffers clean.  Make
+ * sure to only clean buffers which we know we'll be writing.
+ */
+static void clean_buffers(struct page *page, unsigned first_unmapped)
+{
+       unsigned buffer_counter = 0;
+       struct buffer_head *bh, *head;
+       if (!page_has_buffers(page))
+               return;
+       head = page_buffers(page);
+       bh = head;
+
+       do {
+               if (buffer_counter++ == first_unmapped)
+                       break;
+               clear_buffer_dirty(bh);
+               bh = bh->b_this_page;
+       } while (bh != head);
+
+       /*
+        * we cannot drop the bh if the page is not uptodate or a concurrent
+        * readpage would fail to serialize with the bh and it would read from
+        * disk before we reach the platter.
+        */
+       if (buffer_heads_over_limit && PageUptodate(page))
+               try_to_free_buffers(page);
+}
+
 static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
                      void *data)
 {
@@ -591,30 +620,7 @@ alloc_new:
                goto alloc_new;
        }
 
-       /*
-        * OK, we have our BIO, so we can now mark the buffers clean.  Make
-        * sure to only clean buffers which we know we'll be writing.
-        */
-       if (page_has_buffers(page)) {
-               struct buffer_head *head = page_buffers(page);
-               struct buffer_head *bh = head;
-               unsigned buffer_counter = 0;
-
-               do {
-                       if (buffer_counter++ == first_unmapped)
-                               break;
-                       clear_buffer_dirty(bh);
-                       bh = bh->b_this_page;
-               } while (bh != head);
-
-               /*
-                * we cannot drop the bh if the page is not uptodate
-                * or a concurrent readpage would fail to serialize with the bh
-                * and it would read from disk before we reach the platter.
-                */
-               if (buffer_heads_over_limit && PageUptodate(page))
-                       try_to_free_buffers(page);
-       }
+       clean_buffers(page, first_unmapped);
 
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);