From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:34232 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752410AbdH2OOA (ORCPT ); Tue, 29 Aug 2017 10:14:00 -0400 From: Christoph Hellwig To: viro@zeniv.linux.org.uk, axboe@kernel.dk Cc: Milosz Tanski , Goldwyn Rodrigues , mgorman@suse.de, Volker.Lendecke@sernet.de, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH 2/4] fs: support IOCB_NOWAIT in generic_file_buffered_read Date: Tue, 29 Aug 2017 16:13:19 +0200 Message-Id: <20170829141321.4482-3-hch@lst.de> In-Reply-To: <20170829141321.4482-1-hch@lst.de> References: <20170829141321.4482-1-hch@lst.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Milosz Tanski Allow generic_file_buffered_read to bail out early instead of waiting for the page lock or reading a page if IOCB_NOWAIT is specified. Signed-off-by: Milosz Tanski Reviewed-by: Christoph Hellwig Reviewed-by: Jeff Moyer Acked-by: Sage Weil --- mm/filemap.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index 4bcfa74ad802..eed394fd331c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1937,6 +1937,8 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, page = find_get_page(mapping, index); if (!page) { + if (iocb->ki_flags & IOCB_NOWAIT) + goto would_block; page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); @@ -1950,6 +1952,11 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, index, last_index - index); } if (!PageUptodate(page)) { + if (iocb->ki_flags & IOCB_NOWAIT) { + put_page(page); + goto would_block; + } + /* * See comment in do_read_cache_page on why * wait_on_page_locked is used to avoid unnecessarily @@ -2131,6 +2138,8 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, goto readpage; } +would_block: + error = -EAGAIN; out: ra->prev_pos = prev_index; ra->prev_pos <<= PAGE_SHIFT; -- 2.11.0