diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 21a951f10636..ce9a1f90fbb5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3901,7 +3901,8 @@ extern void ext4_ext_release(struct super_block *);
 extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
 			  loff_t len);
 extern int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
-					  loff_t offset, ssize_t len);
+					  loff_t offset, ssize_t len,
+					  ext4_lblk_t *converted);
 extern int ext4_convert_unwritten_extents_atomic(handle_t *handle,
 			struct inode *inode, loff_t offset, ssize_t len);
 extern int ext4_convert_unwritten_io_end_vec(handle_t *handle,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d5f87a7f6c05..1ab1a6e2ed83 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4664,7 +4664,7 @@ static int ext4_alloc_file_blocks(struct file *file, loff_t offset, loff_t len,
 			if (likely(!ret))
 				ret = ext4_convert_unwritten_extents(NULL,
 					inode, (loff_t)map.m_lblk << blkbits,
-					(loff_t)map.m_len << blkbits);
+					(loff_t)map.m_len << blkbits, NULL);
 			if (ret)
 				break;
 		}
@@ -5051,21 +5051,26 @@ int ext4_convert_unwritten_extents_atomic(handle_t *handle, struct inode *inode,
  * all unwritten extents within this range will be converted to
  * written extents.
  *
- * This function is called from the direct IO end io call back
- * function, to convert the fallocated extents after IO is completed.
- * Returns 0 on success.
+ * This function is called from the direct/buffered I/O end io call back
+ * function and FALLOC_FL_WRITE_ZEROES, to convert the fallocated
+ * unwritten extents after data I/O is completed.
+ *
+ * Returns 0 on full success, or a negative error code on partial
+ * success or failure. The number of blocks converted is returned via
+ * @converted.
  */
 int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
-				   loff_t offset, ssize_t len)
+				   loff_t offset, ssize_t len,
+				   ext4_lblk_t *converted)
 {
-	unsigned int max_blocks;
+	ext4_lblk_t max_blocks, conv_blocks = 0;
 	int ret = 0, ret2 = 0, ret3 = 0;
 	struct ext4_map_blocks map;
 	unsigned int blkbits = inode->i_blkbits;
 	unsigned int credits = 0;
 
 	map.m_lblk = offset >> blkbits;
-	max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
+	map.m_len = max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
 
 	if (!handle) {
 		/*
@@ -5073,9 +5078,8 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 		 */
 		credits = ext4_chunk_trans_blocks(inode, max_blocks);
 	}
-	while (ret >= 0 && ret < max_blocks) {
-		map.m_lblk += ret;
-		map.m_len = (max_blocks -= ret);
+
+	while (max_blocks) {
 		if (credits) {
 			handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
 						    credits);
@@ -5092,23 +5096,34 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 		ret = ext4_map_blocks(handle, inode, &map,
 				      EXT4_GET_BLOCKS_IO_CONVERT_EXT |
 				      EXT4_EX_NOCACHE);
-		if (ret <= 0)
+		if (ret <= 0) {
 			ext4_warning(inode->i_sb,
-				     "inode #%llu: block %u: len %u: "
-				     "ext4_ext_map_blocks returned %d",
-				     inode->i_ino, map.m_lblk,
-				     map.m_len, ret);
+				     "inode #%llu: block %u: len %u: ext4_map_blocks returned %d",
+				     inode->i_ino, map.m_lblk, map.m_len, ret);
+			if (unlikely(ret == 0))
+				ret = -EINVAL;
+		} else {
+			conv_blocks += map.m_len;
+		}
+
 		ret2 = ext4_mark_inode_dirty(handle, inode);
 		if (credits) {
 			ret3 = ext4_journal_stop(handle);
 			if (unlikely(ret3))
 				ret2 = ret3;
 		}
-
-		if (ret <= 0 || ret2)
+		ret = ret < 0 ? ret : ret2;
+		if (ret)
 			break;
+
+		map.m_lblk += map.m_len;
+		map.m_len = (max_blocks -= map.m_len);
 	}
-	return ret > 0 ? ret2 : ret;
+	/* Converted some or all blocks successfully? */
+	if (converted)
+		*converted = conv_blocks;
+
+	return ret;
 }
 
 int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
@@ -5131,7 +5146,7 @@ int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
 	list_for_each_entry(io_end_vec, &io_end->list_vec, list) {
 		ret = ext4_convert_unwritten_extents(handle, io_end->inode,
 						     io_end_vec->offset,
-						     io_end_vec->size);
+						     io_end_vec->size, NULL);
 		if (ret)
 			break;
 	}
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 9a16071b719d..45e16799d0c2 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -436,7 +436,8 @@ static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 		error = ext4_convert_unwritten_extents_atomic(NULL, inode, pos,
 							      size);
 	else if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
-		error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
+		error = ext4_convert_unwritten_extents(NULL, inode, pos, size,
+						       NULL);
 	if (error)
 		return error;
 	/*