From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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, 22 Aug 2017 18:17:10 +0200 Message-Id: <20170822161712.11716-3-hch@lst.de> In-Reply-To: <20170822161712.11716-1-hch@lst.de> References: <20170822161712.11716-1-hch@lst.de> 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 4bcfa74ad802..9f60255fb7bb 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); @@ -2042,6 +2044,11 @@ 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)) @@ -2061,6 +2068,12 @@ 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 @@ -2131,6 +2144,8 @@ 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