From: Jens Axboe <axboe@kernel.dk>
To: io-uring@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 04/11] mm: support async buffered reads in generic_file_buffered_read()
Date: Fri, 22 May 2020 14:23:04 -0600 [thread overview]
Message-ID: <20200522202311.10959-5-axboe@kernel.dk> (raw)
In-Reply-To: <20200522202311.10959-1-axboe@kernel.dk>
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 <axboe@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
next prev parent reply other threads:[~2020-05-22 20:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 20:23 [PATCHSET RFC 0/11] Add support for async buffered reads Jens Axboe
2020-05-22 20:23 ` [PATCH 01/11] block: read-ahead submission should imply no-wait as well Jens Axboe
2020-05-22 20:23 ` [PATCH 02/11] mm: allow read-ahead with IOCB_NOWAIT set Jens Axboe
2020-05-22 20:23 ` [PATCH 03/11] mm: add support for async page locking Jens Axboe
2020-05-22 20:57 ` [PATCH v2 " Jens Axboe
2020-05-22 20:23 ` Jens Axboe [this message]
2020-05-22 20:23 ` [PATCH 05/11] fs: add FMODE_BUF_RASYNC Jens Axboe
2020-05-22 20:23 ` [PATCH 06/11] ext4: flag as supporting buffered async reads Jens Axboe
2020-05-22 20:23 ` [PATCH 07/11] block: flag block devices as supporting IOCB_WAITQ Jens Axboe
2020-05-22 20:23 ` [PATCH 08/11] xfs: flag files as supporting buffered async reads Jens Axboe
2020-05-22 20:23 ` [PATCH 09/11] btrfs: " Jens Axboe
2020-05-22 20:23 ` [PATCH 10/11] mm: add kiocb_wait_page_async_init() helper Jens Axboe
2020-05-22 20:23 ` [PATCH 11/11] io_uring: support true async buffered reads, if file provides it Jens Axboe
2020-05-23 1:50 [PATCHSET v2 RFC 0/11] Add support for async buffered reads Jens Axboe
2020-05-23 1:50 ` [PATCH 04/11] mm: support async buffered reads in generic_file_buffered_read() Jens Axboe
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