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[146.199.243.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f351d40sm40459372f8f.26.2026.06.07.00.32.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Jun 2026 00:32:04 -0700 (PDT) From: Dylan Yudaken To: trondmy@kernel.org, anna@kernel.org, linux-nfs@vger.kernel.org Cc: axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Dylan Yudaken Subject: [PATCH v2 1/2] nfs: add nowait version of nfs_start_io_direct Date: Sun, 7 Jun 2026 08:31:54 +0100 Message-ID: <20260607073155.105314-2-dyudaken@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260607073155.105314-1-dyudaken@gmail.com> References: <20260607073155.105314-1-dyudaken@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" nfs_start_io_direct might block on existing operations to the same inode. In order to support NOWAIT O_DIRECT reads, add a non-blocking version of this nfs_start_io_direct that just returns -EAGAIN if locks could not be taken. Signed-off-by: Dylan Yudaken --- fs/nfs/internal.h | 1 + fs/nfs/io.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 18d46b0e71dd..0c9aca624353 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -532,6 +532,7 @@ extern void nfs_end_io_read(struct inode *inode); extern __must_check int nfs_start_io_write(struct inode *inode); extern void nfs_end_io_write(struct inode *inode); extern __must_check int nfs_start_io_direct(struct inode *inode); +extern __must_check int nfs_start_io_direct_nowait(struct inode *inode); extern void nfs_end_io_direct(struct inode *inode); =20 static inline bool nfs_file_io_is_buffered(struct nfs_inode *nfsi) diff --git a/fs/nfs/io.c b/fs/nfs/io.c index 8337f0ae852d..2faf2003faf6 100644 --- a/fs/nfs/io.c +++ b/fs/nfs/io.c @@ -109,6 +109,16 @@ static void nfs_block_buffered(struct nfs_inode *nfsi,= struct inode *inode) } } =20 +static int nfs_block_buffered_nowait(struct nfs_inode *nfsi, struct inode = *inode) +{ + if (!test_bit(NFS_INO_ODIRECT, &nfsi->flags)) { + if (inode->i_mapping->nrpages !=3D 0) + return 1; + set_bit(NFS_INO_ODIRECT, &nfsi->flags); + } + return 0; +} + /** * nfs_start_io_direct - declare the file is being used for direct i/o * @inode: file inode @@ -149,6 +159,37 @@ nfs_start_io_direct(struct inode *inode) return 0; } =20 +/** + * nfs_start_io_direct_nowait - non-blocking variant of nfs_start_io_direc= t() + * @inode: file inode + * + * Try to declare that a direct I/O operation is about to start without + * blocking. + * Ensure all buffered I/O is blocked. + * If this could not be done without blocking then returns -EAGAIN. + */ +int +nfs_start_io_direct_nowait(struct inode *inode) +{ + struct nfs_inode *nfsi =3D NFS_I(inode); + + if (!down_read_trylock(&inode->i_rwsem)) + return -EAGAIN; + if (test_bit(NFS_INO_ODIRECT, &nfsi->flags)) + return 0; + up_read(&inode->i_rwsem); + + /* Slow path: try to flip NFS_INO_ODIRECT without blocking. */ + if (!down_write_trylock(&inode->i_rwsem)) + return -EAGAIN; + if (nfs_block_buffered_nowait(nfsi, inode)) { + up_write(&inode->i_rwsem); + return -EAGAIN; + } + downgrade_write(&inode->i_rwsem); + return 0; +} + /** * nfs_end_io_direct - declare that the direct i/o operation is done * @inode: file inode --=20 2.50.1 From nobody Mon Jun 8 04:19:58 2026 Received: from mail-wr1-f48.google.com (mail-wr1-f48.google.com [209.85.221.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EAAB633E351 for ; Sun, 7 Jun 2026 07:32:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.48 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780817530; cv=none; b=V0QgbLqkkmnQRsI7FEsWTk+Wmje1xx566Snc7OyQ6ZuVcyZa1tJfc3YTF8FMqKHeI/UsCTwKxNiPYNSpRK2rKAIuJLVA797pUr9N638KXIfHsh3aaRxVorFIqZKCspoFWY+fW3Qp6iDsrfFmMxPFFuKQTrltx39tTrT66ARlHbU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780817530; c=relaxed/simple; bh=TcJi1kY6w0L+kvlTtQn8bf3Yvzy8onv7gAt+BEvpDSI=; 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[146.199.243.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f351d40sm40459372f8f.26.2026.06.07.00.32.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Jun 2026 00:32:06 -0700 (PDT) From: Dylan Yudaken To: trondmy@kernel.org, anna@kernel.org, linux-nfs@vger.kernel.org Cc: axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Dylan Yudaken Subject: [PATCH v2 2/2] nfs: expose FMODE_NOWAIT for read-only files Date: Sun, 7 Jun 2026 08:31:55 +0100 Message-ID: <20260607073155.105314-3-dyudaken@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260607073155.105314-1-dyudaken@gmail.com> References: <20260607073155.105314-1-dyudaken@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" NFS O_DIRECT reads already (mostly) handle async requests, with the exception of locking the inode for direct. Handle async requests properly by using nfs_start_io_direct_nowait, and then expose FMODE_NOWAIT since it's now supported for direct reads. Signed-off-by: Dylan Yudaken --- fs/nfs/direct.c | 12 ++++++++++-- fs/nfs/file.c | 16 +++++++++++++++- 2 files changed, 25 insertions(+), 3 deletions(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index 48d89716193a..e626c72495e6 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -466,14 +466,22 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, stru= ct iov_iter *iter, goto out_release; } dreq->l_ctx =3D l_ctx; - if (!is_sync_kiocb(iocb)) + if (!is_sync_kiocb(iocb)) { dreq->iocb =3D iocb; + } else if (iocb->ki_flags & IOCB_NOWAIT) { + result =3D -EAGAIN; + nfs_direct_req_release(dreq); + goto out_release; + } =20 if (user_backed_iter(iter)) dreq->flags =3D NFS_ODIRECT_SHOULD_DIRTY; =20 if (!swap) { - result =3D nfs_start_io_direct(inode); + if (iocb->ki_flags & IOCB_NOWAIT) + result =3D nfs_start_io_direct_nowait(inode); + else + result =3D nfs_start_io_direct(inode); if (result) { /* release the reference that would usually be * consumed by nfs_direct_read_schedule_iovec() diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 25048a3c2364..a0d8f1c1cf10 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -72,8 +72,12 @@ nfs_file_open(struct inode *inode, struct file *filp) return res; =20 res =3D nfs_open(inode, filp); - if (res =3D=3D 0) + if (res =3D=3D 0) { filp->f_mode |=3D FMODE_CAN_ODIRECT; + /* flag NOWAIT on read-only files only */ + if (!(filp->f_mode & FMODE_WRITE)) + filp->f_mode |=3D FMODE_NOWAIT; + } return res; } =20 @@ -166,6 +170,10 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to) if (iocb->ki_flags & IOCB_DIRECT) return nfs_file_direct_read(iocb, to, false); =20 + /* NOWAIT only supported on direct reads */ + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + dprintk("NFS: read(%pD2, %zu@%lu)\n", iocb->ki_filp, iov_iter_count(to), (unsigned long) iocb->ki_pos); @@ -705,6 +713,12 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_= iter *from) =20 trace_nfs_file_write(iocb, from); =20 + /* + * FMODE_NOWAIT is not set for writable files + */ + if (WARN_ON_ONCE(iocb->ki_flags & IOCB_NOWAIT)) + return -EAGAIN; + result =3D nfs_key_timeout_notify(file, inode); if (result) return result; --=20 2.50.1