Re: [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O
From: Michal Hocko <mhocko@kernel.org>
Date: 2019-01-31 10:23:56
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linux-fsdevel, linux-mm, lkml
On Thu 31-01-19 11:15:28, Jiri Kosina wrote:
On Thu, 31 Jan 2019, Michal Hocko wrote:quoted
quoted
diff --git a/mm/filemap.c b/mm/filemap.c index 9f5e323e883e..7bcdd36e629d 100644 --- a/mm/filemap.c +++ b/mm/filemap.c@@ -2075,8 +2075,6 @@ 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);Maybe a stupid question but I am not really familiar with this path but what exactly does prevent a sync read down page_cache_sync_readahead path?page_cache_sync_readahead() only submits the read ahead request(s), it doesn't wait for it to finish.
OK, I guess my question was not precise. What does prevent taking fs locks down the path? -- Michal Hocko SUSE Labs