ocfs2: do not change i_size in write_end for direct io

To support direct io in ocfs2_write_begin_nolock & ocfs2_write_end_nolock.

Append direct io do not change i_size in get block phase.  It only move
to orphan when starting write.  After data is written to disk, it will
delete itself from orphan and update i_size.  So skip i_size change
section in write_begin for direct io.

And when there is no extents alloc, no meta data changes needed for
direct io (since write_begin start trans for 2 reason: alloc extents &
change i_size.  Now none of them needed).  So we can skip start trans
procedure.
Signed-off-by: Ryan Ding <ryan.ding@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/aops.c

@@ -2043,6 +2043,8 @@ static int ocfs2_expand_nonsparse_inode(struct inode *inode,
 	if (ret)
 		mlog_errno(ret);
 
+	/* There is no wc if this is call from direct. */
+	if (wc)
 		wc->w_first_new_cpos =
 			ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
 
@@ -2135,15 +2137,18 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
 		}
 	}
 
+	/* Direct io change i_size late, should not zero tail here. */
+	if (type != OCFS2_WRITE_DIRECT) {
 		if (ocfs2_sparse_alloc(osb))
 			ret = ocfs2_zero_tail(inode, di_bh, pos);
 		else
-		ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos, len,
-						   wc);
+			ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos,
+							   len, wc);
 		if (ret) {
 			mlog_errno(ret);
 			goto out;
 		}
+	}
 
 	ret = ocfs2_check_range_for_refcount(inode, pos, len);
 	if (ret < 0) {
@@ -2203,8 +2208,9 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
 
 		credits = ocfs2_calc_extend_credits(inode->i_sb,
 						    &di->id2.i_list);
-
-	}
+	} else if (type == OCFS2_WRITE_DIRECT)
+		/* direct write needs not to start trans if no extents alloc. */
+		goto success;
 
 	/*
 	 * We have to zero sparse allocated clusters, unwritten extent clusters,
@@ -2402,13 +2408,15 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
 	handle_t *handle = wc->w_handle;
 	struct page *tmppage;
 
-	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
-			OCFS2_JOURNAL_ACCESS_WRITE);
+	if (handle) {
+		ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode),
+				wc->w_di_bh, OCFS2_JOURNAL_ACCESS_WRITE);
 		if (ret) {
 			copied = ret;
 			mlog_errno(ret);
 			goto out;
 		}
+	}
 
 	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
 		ocfs2_write_end_inline(inode, pos, len, &copied, di, wc);
@@ -2450,13 +2458,15 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
 		}
 
 		if (page_has_buffers(tmppage)) {
-			if (ocfs2_should_order_data(inode))
-				ocfs2_jbd2_file_inode(wc->w_handle, inode);
+			if (handle && ocfs2_should_order_data(inode))
+				ocfs2_jbd2_file_inode(handle, inode);
 			block_commit_write(tmppage, from, to);
 		}
 	}
 
 out_write_size:
+	/* Direct io do not update i_size here. */
+	if (wc->w_type != OCFS2_WRITE_DIRECT) {
 		pos += copied;
 		if (pos > i_size_read(inode)) {
 			i_size_write(inode, pos);
@@ -2468,6 +2478,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
 		di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
 		di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
 		ocfs2_update_inode_fsync_trans(handle, inode, 1);
+	}
+	if (handle)
 		ocfs2_journal_dirty(handle, wc->w_di_bh);
 
 out:
@@ -2478,6 +2490,7 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
 	 */
 	ocfs2_unlock_pages(wc);
 
+	if (handle)
 		ocfs2_commit_trans(osb, handle);
 
 	ocfs2_run_deallocs(osb, &wc->w_dealloc);