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Thu, 18 Jun 2020 07:44:09 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, Jens Axboe , Johannes Weiner Subject: [PATCH 08/15] mm: support async buffered reads in generic_file_buffered_read() Date: Thu, 18 Jun 2020 08:43:48 -0600 Message-Id: <20200618144355.17324-9-axboe@kernel.dk> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200618144355.17324-1-axboe@kernel.dk> References: <20200618144355.17324-1-axboe@kernel.dk> Reply-To: "[PATCHSET v7 0/15]"@smtpin11.hostedemail.com, Add@smtpin11.hostedemail.com, support@smtpin11.hostedemail.com, for@smtpin11.hostedemail.com, async@smtpin11.hostedemail.com, buffered@smtpin11.hostedemail.com, reads@smtpin11.hostedemail.com MIME-Version: 1.0 X-Rspamd-Queue-Id: B2E03180F8B86 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. Acked-by: Johannes Weiner Signed-off-by: Jens Axboe --- mm/filemap.c | 38 +++++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 11 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index e8aaf43bee9f..a5b1fa8f7ce4 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1210,6 +1210,14 @@ static int __wait_on_page_locked_async(struct page= *page, return ret; } =20 +static int wait_on_page_locked_async(struct page *page, + struct wait_page_queue *wait) +{ + if (!PageLocked(page)) + return 0; + return __wait_on_page_locked_async(compound_head(page), wait, false); +} + /** * put_and_wait_on_page_locked - Drop a reference and wait for it to be = unlocked * @page: The page to wait for. @@ -2049,17 +2057,25 @@ 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 =3D wait_on_page_locked_killable(page); + if (iocb->ki_flags & IOCB_WAITQ) { + if (written) { + put_page(page); + goto out; + } + error =3D wait_on_page_locked_async(page, + iocb->ki_waitq); + } else { + if (iocb->ki_flags & IOCB_NOWAIT) { + put_page(page); + goto would_block; + } + error =3D wait_on_page_locked_killable(page); + } if (unlikely(error)) goto readpage_error; if (PageUptodate(page)) @@ -2147,7 +2163,10 @@ ssize_t generic_file_buffered_read(struct kiocb *i= ocb, =20 page_not_up_to_date: /* Get exclusive access to the page ... */ - error =3D lock_page_killable(page); + if (iocb->ki_flags & IOCB_WAITQ) + error =3D lock_page_async(page, iocb->ki_waitq); + else + error =3D lock_page_killable(page); if (unlikely(error)) goto readpage_error; =20 @@ -2190,10 +2209,7 @@ ssize_t generic_file_buffered_read(struct kiocb *i= ocb, } =20 if (!PageUptodate(page)) { - if (iocb->ki_flags & IOCB_WAITQ) - error =3D lock_page_async(page, iocb->ki_waitq); - else - error =3D lock_page_killable(page); + error =3D lock_page_killable(page); if (unlikely(error)) goto readpage_error; if (!PageUptodate(page)) { --=20 2.27.0