From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:37276 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751203AbdF3SPt (ORCPT ); Fri, 30 Jun 2017 14:15:49 -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 2/3] fs: support IOCB_NOWAIT in generic_file_buffered_read Date: Fri, 30 Jun 2017 11:15:20 -0700 Message-Id: <20170630181521.29148-3-hch@lst.de> In-Reply-To: <20170630181521.29148-1-hch@lst.de> References: <20170630181521.29148-1-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 | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index 3df0a57cd48e..d021931c8e74 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1843,6 +1843,8 @@ 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); @@ -1948,6 +1950,11 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, continue; page_not_up_to_date: + if (iocb->ki_flags & IOCB_NOWAIT) { + put_page(page); + goto would_block; + } + /* Get exclusive access to the page ... */ error = lock_page_killable(page); if (unlikely(error)) @@ -1967,6 +1974,12 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, goto page_ok; } + if (iocb->ki_flags & IOCB_NOWAIT) { + unlock_page(page); + put_page(page); + goto would_block; + } + readpage: /* * A previous I/O error may have been due to temporary @@ -2037,6 +2050,8 @@ 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