On Tue 29-08-17 16:13:19, Christoph Hellwig wrote:
> From: Milosz Tanski <milosz@xxxxxxxxx>
>
> 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 <milosz@xxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
> Acked-by: Sage Weil <sage@xxxxxxxxxx>
This looks good to me now. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> 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
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
