[PATCH v2] ext4: fix fast commit may miss tracking range for FALLOC_FL_ZERO_RANGE

[Xin Yin <yinxin.x@bytedance.com>]

when call falloc with FALLOC_FL_ZERO_RANGE, to set an range to unwritten,
which has been already initialized. If the range is align to blocksize,
fast commit will not track range for this change.

Also track range for unwritten range in ext4_map_blocks().

Signed-off-by: Xin Yin <yinxin.x@bytedance.com>
---
v2: change to track unwritten range in ext4_map_blocks()
---
 fs/ext4/extents.c | 2 --
 fs/ext4/inode.c   | 7 ++++---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 9229ab1f99c5..6bce319f3bcd 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4599,8 +4599,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 	ret = ext4_mark_inode_dirty(handle, inode);
 	if (unlikely(ret))
 		goto out_handle;
-	ext4_fc_track_range(handle, inode, offset >> inode->i_sb->s_blocksize_bits,
-			(offset + len - 1) >> inode->i_sb->s_blocksize_bits);
 	/* Zero out partial block at the edges of the range */
 	ret = ext4_zero_partial_blocks(handle, inode, offset, len);
 	if (ret >= 0)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0afab6d5c65b..47ad4b8cb503 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -741,10 +741,11 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 			if (ret)
 				return ret;
 		}
-		ext4_fc_track_range(handle, inode, map->m_lblk,
-			    map->m_lblk + map->m_len - 1);
 	}
-
+	if (retval > 0 && (map->m_flags & EXT4_MAP_UNWRITTEN ||
+				map->m_flags & EXT4_MAP_MAPPED))
+		ext4_fc_track_range(handle, inode, map->m_lblk,
+					map->m_lblk + map->m_len - 1);
 	if (retval < 0)
 		ext_debug(inode, "failed with err %d\n", retval);
 	return retval;
-- 
2.20.1