[GFS2] Clean up ordered write code

The following patch removes the ordered write processing from
databuf_lo_before_commit() and moves it to log.c. This has the effect of
greatly simplyfying databuf_lo_before_commit() and well as potentially
making the ordered write code more efficient.

As a side effect of this, its now possible to remove ordered buffers
from the ordered buffer list at any time, so we now make use of this in
invalidatepage and releasepage to ensure timely release of these
buffers.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 46 insertions, 4 deletions

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 8407d1db4eac..dd1ea491ddcb 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -616,13 +616,50 @@ static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
         return dblock;
 }
 
+static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
+{
+        struct gfs2_bufdata *bd;
+
+        lock_buffer(bh);
+        gfs2_log_lock(sdp);
+        clear_buffer_dirty(bh);
+        bd = bh->b_private;
+        if (bd) {
+                if (!list_empty(&bd->bd_le.le_list)) {
+                        if (!buffer_pinned(bh))
+                                list_del_init(&bd->bd_le.le_list);
+                }
+        }
+        bh->b_bdev = NULL;
+        clear_buffer_mapped(bh);
+        clear_buffer_req(bh);
+        clear_buffer_new(bh);
+        gfs2_log_unlock(sdp);
+        unlock_buffer(bh);
+}
+
 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 {
+        struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
+        struct buffer_head *bh, *head;
+        unsigned long pos = 0;
+
         BUG_ON(!PageLocked(page));
         if (offset == 0)
                 ClearPageChecked(page);
+        if (!page_has_buffers(page))
+                goto out;
 
-        block_invalidatepage(page, offset);
+        bh = head = page_buffers(page);
+        do {
+                if (offset <= pos)
+                        gfs2_discard(sdp, bh);
+                pos += bh->b_size;
+                bh = bh->b_this_page;
+        } while (bh != head);
+out:
+        if (offset == 0)
+                try_to_release_page(page, 0);
 }
 
 /**
@@ -732,9 +769,14 @@ int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
                 if (bd) {
                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
-                        bd->bd_bh = NULL;
-                        if (!list_empty(&bd->bd_le.le_list))
-                                bd = NULL;
+                        if (!list_empty(&bd->bd_le.le_list)) {
+                                if (!buffer_pinned(bh))
+                                        list_del_init(&bd->bd_le.le_list);
+                                else
+                                        bd = NULL;
+                        }
+                        if (bd)
+                                bd->bd_bh = NULL;
                         bh->b_private = NULL;
                 }
                 gfs2_log_unlock(sdp);