[PATCH 2/4] fs: support IOCB_NOWAIT in generic_file_buffered_read
From: Christoph Hellwig <hch@lst.de>
Date: 2017-08-29 14:14:00
Also in:
linux-fsdevel
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
From: Milosz Tanski <redacted> 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 <redacted> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Moyer <redacted> Acked-by: Sage Weil <redacted> --- 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