[PATCH 3/3] iomap: use filemap_range_needs_writeback() for O_DIRECT IO

From: Jens Axboe <axboe@kernel.dk>
To: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Cc: hch@infradead.org, akpm@linux-foundation.org,
	Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 3/3] iomap: use filemap_range_needs_writeback() for O_DIRECT IO
Date: Mon,  8 Feb 2021 15:18:29 -0700	[thread overview]
Message-ID: <20210208221829.17247-4-axboe@kernel.dk> (raw)
In-Reply-To: <20210208221829.17247-1-axboe@kernel.dk>

For the generic page cache read/write helpers, use the better variant
of checking for the need to call filemap_write_and_wait_range() when
doing O_DIRECT reads or writes. 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>
---
 fs/iomap/direct-io.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 933f234d5bec..2561e50c763a 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -479,17 +479,17 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 	}
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (filemap_range_has_page(mapping, pos, end)) {
+		if (filemap_range_needs_writeback(mapping, pos, end)) {
 			ret = -EAGAIN;
 			goto out_free_dio;
 		}
 		flags |= IOMAP_NOWAIT;
+	} else {
+		ret = filemap_write_and_wait_range(mapping, pos, end);
+		if (ret)
+			goto out_free_dio;
 	}
 
-	ret = filemap_write_and_wait_range(mapping, pos, end);
-	if (ret)
-		goto out_free_dio;
-
 	if (iov_iter_rw(iter) == WRITE) {
 		/*
 		 * Try to invalidate cache pages for the range we are writing.
-- 
2.30.0

