| Message ID | f5247b60e7abbd2ff850cd108491f53a2e0c501a.1610207781.git.asml.silence@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/filemap: don't revert iter on -EIOCBQUEUED | expand |
On Sat, Jan 09, 2021 at 04:00:32PM +0000, Pavel Begunkov wrote: > 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. Looks good, Reviewed-by: Christoph Hellwig <hch@lst.de>
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; }
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 <asml.silence@gmail.com> --- mm/filemap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)