ext4: remove buffer_uninit handling

There isn't any need for setting BH_Uninit on buffers anymore.  It was
only used to signal we need to mark io_end as needing extent
conversion in add_bh_to_extent() but now we can mark the io_end
directly when mapping extent.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -2653,20 +2653,17 @@ extern void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp);
 extern int ext4_mmp_csum_verify(struct super_block *sb,
 				struct mmp_struct *mmp);
 
-/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
+/*
+ * Note that these flags will never ever appear in a buffer_head's state flag.
+ * See EXT4_MAP_... to see where this is used.
+ */
 enum ext4_state_bits {
 	BH_Uninit	/* blocks are allocated but uninitialized on disk */
 	 = BH_JBDPrivateStart,
 	BH_AllocFromCluster,	/* allocated blocks were part of already
-				 * allocated cluster. Note that this flag will
-				 * never, ever appear in a buffer_head's state
-				 * flag. See EXT4_MAP_FROM_CLUSTER to see where
-				 * this is used. */
+				 * allocated cluster. */
 };
 
-BUFFER_FNS(Uninit, uninit)
-TAS_BUFFER_FNS(Uninit, uninit)
-
 /*
  * Add new method to test whether block and inode bitmaps are properly
  * initialized. With uninit_bg reading the block from disk is not enough

fs/ext4/inode.c

@@ -2047,8 +2047,6 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
 					clear_buffer_delay(bh);
 					bh->b_blocknr = pblock++;
 				}
-				if (mpd->map.m_flags & EXT4_MAP_UNINIT)
-					set_buffer_uninit(bh);
 				clear_buffer_unwritten(bh);
 			} while (++lblk < blocks &&
 				 (bh = bh->b_this_page) != head);
@@ -2110,6 +2108,8 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
 	err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
 	if (err < 0)
 		return err;
+	if (map->m_flags & EXT4_MAP_UNINIT)
+		ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
 
 	BUG_ON(map->m_len == 0);
 	if (map->m_flags & EXT4_MAP_NEW) {

fs/ext4/page-io.c

@@ -369,7 +369,6 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
 			    struct inode *inode,
 			    struct buffer_head *bh)
 {
-	ext4_io_end_t *io_end;
 	int ret;
 
 	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
@@ -384,9 +383,6 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
 	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
 	if (ret != bh->b_size)
 		goto submit_and_retry;
-	io_end = io->io_end;
-	if (test_clear_buffer_uninit(bh))
-		ext4_set_io_unwritten_flag(inode, io_end);
 	io->io_next_block++;
 	return 0;
 }