ext3: Try to avoid starting a transaction in writepage for data=writepage

This does the same as commit 9e80d407736161d9b8b0c5a0d44f786e44c322ea
(avoid starting a transaction when no block allocation is needed)
but for data=writeback mode of ext3. We also cleanup the data=ordered
case a bit to stick to coding style...

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 18 insertions, 5 deletions

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 466a332e0bd..fcfa2436185 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1521,12 +1521,16 @@ static int ext3_ordered_writepage(struct page *page,
         if (!page_has_buffers(page)) {
                 create_empty_buffers(page, inode->i_sb->s_blocksize,
                                 (1 << BH_Dirty)|(1 << BH_Uptodate));
-        } else if (!walk_page_buffers(NULL, page_buffers(page), 0, PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {
-                /* Provide NULL instead of get_block so that we catch bugs if buffers weren't really mapped */
-                return block_write_full_page(page, NULL, wbc);
+                page_bufs = page_buffers(page);
+        } else {
+                page_bufs = page_buffers(page);
+                if (!walk_page_buffers(NULL, page_bufs, 0, PAGE_CACHE_SIZE,
+                                       NULL, buffer_unmapped)) {
+                        /* Provide NULL get_block() to catch bugs if buffers
+                         * weren't really mapped */
+                        return block_write_full_page(page, NULL, wbc);
+                }
         }
-        page_bufs = page_buffers(page);
-
         handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
 
         if (IS_ERR(handle)) {
@@ -1581,6 +1585,15 @@ static int ext3_writeback_writepage(struct page *page,
         if (ext3_journal_current_handle())
                 goto out_fail;
 
+        if (page_has_buffers(page)) {
+                if (!walk_page_buffers(NULL, page_buffers(page), 0,
+                                      PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {
+                        /* Provide NULL get_block() to catch bugs if buffers
+                         * weren't really mapped */
+                        return block_write_full_page(page, NULL, wbc);
+                }
+        }
+
         handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
         if (IS_ERR(handle)) {
                 ret = PTR_ERR(handle);