Jan Kara reports that commit bc264fea0f6f subtly changed error handling behavior in iomap_iter() in the case where both iter.status and ->iomap_end() return error codes. Previously, iter.status had priority and would return to the caller regardless of the ->iomap_end() result. After the change, an ->iomap_end() error returns immediately. This had the unexpected side effect of enabling a DIO fallback to buffered write on ext4 because ->iomap_end() could return -ENOTBLK and overload an -EINVAL error from the core iomap direct I/O code. This has been fixed independently in ext4, but nonetheless the change in iomap was unintentional. Since other filesystems may use this in similar ways, restore long standing behavior and always return the value of iter.status if it happens to contain an error code. Fixes: bc264fea0f6f ("iomap: support incremental iomap_iter advances") Diagnosed-by: Jan Kara Signed-off-by: Brian Foster --- fs/iomap/iter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c index cef77ca0c20b..7cc4599b9c9b 100644 --- a/fs/iomap/iter.c +++ b/fs/iomap/iter.c @@ -80,7 +80,7 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) iomap_length_trim(iter, iter->iter_start_pos, olen), advanced, iter->flags, &iter->iomap); - if (ret < 0 && !advanced) + if (ret < 0 && !advanced && !iter->status) return ret; } -- 2.51.0