[PATCH 2/3] mm: use filemap_range_needs_writeback() for O_DIRECT reads
From: Jens Axboe <axboe@kernel.dk>
Date: 2021-02-24 16:46:22
Also in:
linux-fsdevel
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
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 13338f877677..77f1b527541e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -2645,8 +2645,8 @@ 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)) return -EAGAIN; } else { retval = filemap_write_and_wait_range(mapping,
--
2.30.0