Currently, if I/O is enqueued for async execution direct paths of
generic_file_{read,write}_iter() will always revert the iter. There are
no users expecting that, and that is also costly. Leave iterators as is
on -EIOCBQUEUED.Signed-off-by: Pavel Begunkov <[email protected]> --- mm/filemap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 5bc672d30143..2e1686e09425 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2633,7 +2633,8 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) iocb->ki_pos += retval; count -= retval; } - iov_iter_revert(iter, count - iov_iter_count(iter)); + if (retval != -EIOCBQUEUED) + iov_iter_revert(iter, count - iov_iter_count(iter)); /* * Btrfs can have a short DIO read if we encounter @@ -3458,7 +3459,8 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) } iocb->ki_pos = pos; } - iov_iter_revert(from, write_len - iov_iter_count(from)); + if (written != -EIOCBQUEUED) + iov_iter_revert(from, write_len - iov_iter_count(from)); out: return written; } -- 2.24.0
