From nobody Sun Dec 14 12:02:35 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D78693308A for ; Fri, 10 May 2024 02:39:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715308754; cv=none; b=DOW9j8/xanDcKJucGcwDd2J+1whaW7/9Cx+KjCrgURLdpNZAcdbhHKDyaNJBPHG2rG2Fe8rLD8tx9VGzGa04RrIuLimyZbPKZF4BFo0ibAdW+YpaWJEPHanlNm+Vqldfvn38ERObF8j+p8bsuz5giOPxHcUSEr+9n4L1Y/qDM78= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715308754; c=relaxed/simple; bh=M3iK44q4XaDBGfbEx+OpWbmqokN+nvYknGFBDDBsslM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=fSIQBXPJpyeOTpQw63Vy00I6hBK++O8gIeIjvIiCE2smZ4Hbsl++WaaEhbmzL7DBJ+L8L+gD1vT9AfRajbw6uA2a8D/wPXdYkBbdM2AO6bZseYXzmp/+1c1bwVYh1Jr9cnFpaiOds+G62nviRxgJj0WMHj3xIG/h/BUvMB5hQzU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DqMOeopC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DqMOeopC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CD39C116B1; Fri, 10 May 2024 02:39:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715308754; bh=M3iK44q4XaDBGfbEx+OpWbmqokN+nvYknGFBDDBsslM=; h=From:To:Cc:Subject:Date:From; b=DqMOeopC5rR16hKDZK7Cd4bMFWFhJs8c2volLMTdFdL3rj5urU9Vo36UaR0n9B2sP bBe9S9+Ra4i160s7SEsY/+aiO1BeGFPNiJt5TNsHVYuYKoFM5vc+PjfOjCLnjqBItb BGh3SFIxjtVkQuc8XoTZZwokVMR0+ximqKniJNBMQeOJBHkcBbbLviEvANx0jHFmdS RiT1vtHW+c+hOw/Totn4leoaPkqacGkkS2Brr2Gg9qhcJEEqvyhqbciRyk9VPtyaxo bQpNI23maOeAe4EckcnGqQ/kj/cup3zsut0L68wCJcxCyteWyRqUrtmW9gYq9hk/yG UMO2tAUptA+3A== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Subject: [PATCH v2] f2fs: fix to avoid racing in between read and OPU dio write Date: Fri, 10 May 2024 10:39:06 +0800 Message-Id: <20240510023906.281700-1-chao@kernel.org> X-Mailer: git-send-email 2.40.1 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" If lfs mode is on, buffered read may race w/ OPU dio write as below, it may cause buffered read hits unwritten data unexpectly, and for dio read, the race condition exists as well. Thread A Thread B - f2fs_file_write_iter - f2fs_dio_write_iter - __iomap_dio_rw - f2fs_iomap_begin - f2fs_map_blocks - __allocate_data_block - allocated blkaddr #x - iomap_dio_submit_bio - f2fs_file_read_iter - filemap_read - f2fs_read_data_folio - f2fs_mpage_readpages - f2fs_map_blocks : get blkaddr #x - f2fs_submit_read_bio IRQ - f2fs_read_end_io : read IO on blkaddr #x complete IRQ - iomap_dio_bio_end_io : direct write IO on blkaddr #x complete This patch introduces a new per-inode i_opu_rwsem lock to avoid such race condition. Fixes: f847c699cff3 ("f2fs: allow out-place-update for direct IO in LFS mod= e") Signed-off-by: Chao Yu --- v2: - fix to cover dio read path w/ i_opu_rwsem as well. fs/f2fs/f2fs.h | 1 + fs/f2fs/file.c | 28 ++++++++++++++++++++++++++-- fs/f2fs/super.c | 1 + 3 files changed, 28 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 30058e16a5d0..91cf4b3d6bc6 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -847,6 +847,7 @@ struct f2fs_inode_info { /* avoid racing between foreground op and gc */ struct f2fs_rwsem i_gc_rwsem[2]; struct f2fs_rwsem i_xattr_sem; /* avoid racing between reading and changi= ng EAs */ + struct f2fs_rwsem i_opu_rwsem; /* avoid racing between buf read and opu d= io write */ =20 int i_extra_isize; /* size of extra space located in i_addr */ kprojid_t i_projid; /* id for project quota */ diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 72ce1a522fb2..4ec260af321f 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -4445,6 +4445,7 @@ static ssize_t f2fs_dio_read_iter(struct kiocb *iocb,= struct iov_iter *to) const loff_t pos =3D iocb->ki_pos; const size_t count =3D iov_iter_count(to); struct iomap_dio *dio; + bool do_opu =3D f2fs_lfs_mode(sbi); ssize_t ret; =20 if (count =3D=3D 0) @@ -4457,8 +4458,14 @@ static ssize_t f2fs_dio_read_iter(struct kiocb *iocb= , struct iov_iter *to) ret =3D -EAGAIN; goto out; } + if (do_opu && !f2fs_down_read_trylock(&fi->i_opu_rwsem)) { + f2fs_up_read(&fi->i_gc_rwsem[READ]); + ret =3D -EAGAIN; + goto out; + } } else { f2fs_down_read(&fi->i_gc_rwsem[READ]); + f2fs_down_read(&fi->i_opu_rwsem); } =20 /* @@ -4477,6 +4484,7 @@ static ssize_t f2fs_dio_read_iter(struct kiocb *iocb,= struct iov_iter *to) ret =3D iomap_dio_complete(dio); } =20 + f2fs_up_read(&fi->i_opu_rwsem); f2fs_up_read(&fi->i_gc_rwsem[READ]); =20 file_accessed(file); @@ -4523,7 +4531,13 @@ static ssize_t f2fs_file_read_iter(struct kiocb *ioc= b, struct iov_iter *to) if (f2fs_should_use_dio(inode, iocb, to)) { ret =3D f2fs_dio_read_iter(iocb, to); } else { + bool do_opu =3D f2fs_lfs_mode(F2FS_I_SB(inode)); + + if (do_opu) + f2fs_down_read(&F2FS_I(inode)->i_opu_rwsem); ret =3D filemap_read(iocb, to, 0); + if (do_opu) + f2fs_up_read(&F2FS_I(inode)->i_opu_rwsem); if (ret > 0) f2fs_update_iostat(F2FS_I_SB(inode), inode, APP_BUFFERED_READ_IO, ret); @@ -4748,14 +4762,22 @@ static ssize_t f2fs_dio_write_iter(struct kiocb *io= cb, struct iov_iter *from, ret =3D -EAGAIN; goto out; } + if (do_opu && !f2fs_down_write_trylock(&fi->i_opu_rwsem)) { + f2fs_up_read(&fi->i_gc_rwsem[READ]); + f2fs_up_read(&fi->i_gc_rwsem[WRITE]); + ret =3D -EAGAIN; + goto out; + } } else { ret =3D f2fs_convert_inline_inode(inode); if (ret) goto out; =20 f2fs_down_read(&fi->i_gc_rwsem[WRITE]); - if (do_opu) + if (do_opu) { f2fs_down_read(&fi->i_gc_rwsem[READ]); + f2fs_down_write(&fi->i_opu_rwsem); + } } =20 /* @@ -4779,8 +4801,10 @@ static ssize_t f2fs_dio_write_iter(struct kiocb *ioc= b, struct iov_iter *from, ret =3D iomap_dio_complete(dio); } =20 - if (do_opu) + if (do_opu) { + f2fs_up_write(&fi->i_opu_rwsem); f2fs_up_read(&fi->i_gc_rwsem[READ]); + } f2fs_up_read(&fi->i_gc_rwsem[WRITE]); =20 if (ret < 0) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index daf2c4dbe150..b4ed3b094366 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1428,6 +1428,7 @@ static struct inode *f2fs_alloc_inode(struct super_bl= ock *sb) init_f2fs_rwsem(&fi->i_gc_rwsem[READ]); init_f2fs_rwsem(&fi->i_gc_rwsem[WRITE]); init_f2fs_rwsem(&fi->i_xattr_sem); + init_f2fs_rwsem(&fi->i_opu_rwsem); =20 /* Will be used by directory only */ fi->i_dir_level =3D F2FS_SB(sb)->dir_level; --=20 2.40.1