Use the async page locking infrastructure, if IOCB_WAITQ is set in the
passed in iocb. The caller must expect an -EIOCBQUEUED return value,
which means that IO is started but not done yet. This is similar to how
O_DIRECT signals the same operation. Once the callback is received by
the caller for IO completion, the caller must retry the operation.
Signed-off-by: Jens Axboe <ax...@kernel.dk>
---
mm/filemap.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 0bc77f431bea..d9d65c74b2f0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2074,17 +2074,25 @@ 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
* serialisations and why it's safe.
*/
- error = wait_on_page_locked_killable(page);
+ if (iocb->ki_flags & IOCB_WAITQ) {
+ if (written) {
+ put_page(page);
+ goto out;
+ }
+ error = wait_on_page_locked_async(page,
+ iocb->private);
+ } else {
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ put_page(page);
+ goto would_block;
+ }
+ error = wait_on_page_locked_killable(page);
+ }
if (unlikely(error))
goto readpage_error;
if (PageUptodate(page))
@@ -2172,7 +2180,10 @@ static ssize_t generic_file_buffered_read(struct kiocb
*iocb,
page_not_up_to_date:
/* Get exclusive access to the page ... */
- error = lock_page_killable(page);
+ if (iocb->ki_flags & IOCB_WAITQ)
+ error = lock_page_async(page, iocb->private);
+ else
+ error = lock_page_killable(page);
if (unlikely(error))
goto readpage_error;
--
2.26.2
