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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: 8bit 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); 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) } } +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 != 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; } +/** + * nfs_start_io_direct_nowait - non-blocking variant of nfs_start_io_direct() + * @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 = 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 -- 2.50.1