Re: [PATCH 2/3] mm: use filemap_range_needs_writeback() for O_DIRECT reads

On 2/9/21 12:48 AM, Christoph Hellwig wrote:

On Mon, Feb 08, 2021 at 07:30:07PM -0700, Jens Axboe wrote:

quoted

For the generic page cache read helper, use the better variant of checking
for the need to call filemap_write_and_wait_range() when doing O_DIRECT
reads. This avoids falling back to the slow path for IOCB_NOWAIT, if there
are no pages to wait for (or write out).

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 mm/filemap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 6a58d50fbd31..c80acb80e8f7 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c

@@ -2643,8 +2643,8 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 
 		size = i_size_read(inode);
 		if (iocb->ki_flags & IOCB_NOWAIT) {
-			if (filemap_range_has_page(mapping, iocb->ki_pos,
-						   iocb->ki_pos + count - 1))
+			if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
+							  iocb->ki_pos + count - 1))

Please avoid the overy long line, which is trivial to do by using the
normal two tab indent for the continuation.

Sure, fixed.

-- 
Jens Axboe