From: Milosz Tanski <[email protected]> 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 <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Jeff Moyer <[email protected]> Acked-by: Sage Weil <[email protected]> --- 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
