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>

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 466a332..fcfa243 100644 (file)
--- 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);