From mboxrd@z Thu Jan 1 00:00:00 1970 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 2808034BA33 for ; Wed, 17 Sep 2025 18:18:47 +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=1758133129; cv=none; b=VtAQlzXNoOFZ84LSarKi2ofKi0Zx5f5e9wsXpqcrBzmRwI6hfBdvlZ2lYaY8fBnS+y3XB9OiRzvfKD+HcgKG8SMGrh2zqChTkBpQuSeGXtn5az9XsZ1fnOKipxNLutI7oQk7LHNGXnwe4Qz50sV5ftcdFstmkuwDDF1rFrx5Ecw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758133129; c=relaxed/simple; bh=j95xuByIqE8j2AS2l7mc5MMBDSXFcqG0QCgbYN4k3Ro=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ki7rOOvPAS2PbvnelVnPRq5NPlxJ00hrFkCLyRHf4lsJWL3WQHf9t4z6D48fQOcQuF/ArDiDtfp1bVCoLrKXOT7V7opZUdsMdZfdlhx8hzjcCMoSJyOZVwrAqANM7r9PYQKMWRF++4v3o4nVcYx17MIwwkwj696zhQRPBcRRXx4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dzfbF5fP; 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="dzfbF5fP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64015C4CEE7; Wed, 17 Sep 2025 18:18:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758133127; bh=j95xuByIqE8j2AS2l7mc5MMBDSXFcqG0QCgbYN4k3Ro=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dzfbF5fPNALec9v+OllMljtu5Sg/Nykq+aH3kpikDoo4CQwHWCYkcXuGDPROPXi8S f4wxMy9nd49/359JD45shSOPqVOokFI+EfCEgjB20ox1v3A6ucnZ52bpYtZx9Zu/mF d9sSOcY+/J8C2hZy28sCIbFZIguydD7AExgLGgoz8G++uo0/DvKYcMhE8uCcjvmocF Z2pNOFPU+iFUoewqrsmVMxKqS2Xe/OzvJ51pDUlDeNHvbhR7ZCVqlI5uy7VgdaChqY pT8Gl5iNy4l/nxsit3N7OH9y18nJUJ6wn8eWHPWbD3ZwnH76oRN6OpfrFmUTJBTvX7 SSI1wrxblug2w== From: Mike Snitzer To: Anna Schumaker Cc: Trond Myklebust , linux-nfs@vger.kernel.org Subject: [PATCH v10 2/7] nfs/localio: avoid issuing misaligned IO using O_DIRECT Date: Wed, 17 Sep 2025 14:18:38 -0400 Message-ID: <20250917181843.33865-3-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250917181843.33865-1-snitzer@kernel.org> References: <20250917181843.33865-1-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add nfsd_file_dio_alignment and use it to avoid issuing misaligned IO using O_DIRECT. Any misaligned DIO falls back to using buffered IO. Because misaligned DIO is now handled safely, remove the nfs modparam 'localio_O_DIRECT_semantics' that was added to require users opt-in to the requirement that all O_DIRECT be properly DIO-aligned. Also, introduce nfs_iov_iter_aligned_bvec() which is a variant of iov_iter_aligned_bvec() that also verifies the offset associated with an iov_iter is DIO-aligned. NOTE: in a parallel effort, iov_iter_aligned_bvec() is being removed along with iov_iter_is_aligned(). Lastly, add pr_info_ratelimited if underlying filesystem returns -EINVAL because it was made to try O_DIRECT for IO that is not DIO-aligned (shouldn't happen, so its best to be louder if it does). Fixes: 3feec68563d ("nfs/localio: add direct IO enablement with sync and async IO support") Signed-off-by: Mike Snitzer --- fs/nfs/localio.c | 69 ++++++++++++++++++++++++++++++++------ fs/nfsd/localio.c | 11 ++++++ include/linux/nfslocalio.h | 2 ++ 3 files changed, 72 insertions(+), 10 deletions(-) diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c index 42ea50d42c995..380407c41822c 100644 --- a/fs/nfs/localio.c +++ b/fs/nfs/localio.c @@ -49,11 +49,6 @@ struct nfs_local_fsync_ctx { static bool localio_enabled __read_mostly = true; module_param(localio_enabled, bool, 0644); -static bool localio_O_DIRECT_semantics __read_mostly = false; -module_param(localio_O_DIRECT_semantics, bool, 0644); -MODULE_PARM_DESC(localio_O_DIRECT_semantics, - "LOCALIO will use O_DIRECT semantics to filesystem."); - static inline bool nfs_client_is_local(const struct nfs_client *clp) { return !!rcu_access_pointer(clp->cl_uuid.net); @@ -322,12 +317,9 @@ nfs_local_iocb_alloc(struct nfs_pgio_header *hdr, return NULL; } - if (localio_O_DIRECT_semantics && - test_bit(NFS_IOHDR_ODIRECT, &hdr->flags)) { - iocb->kiocb.ki_filp = file; + init_sync_kiocb(&iocb->kiocb, file); + if (test_bit(NFS_IOHDR_ODIRECT, &hdr->flags)) iocb->kiocb.ki_flags = IOCB_DIRECT; - } else - init_sync_kiocb(&iocb->kiocb, file); iocb->kiocb.ki_pos = hdr->args.offset; iocb->hdr = hdr; @@ -337,6 +329,30 @@ nfs_local_iocb_alloc(struct nfs_pgio_header *hdr, return iocb; } +static bool nfs_iov_iter_aligned_bvec(const struct iov_iter *i, + loff_t offset, unsigned int addr_mask, unsigned int len_mask) +{ + const struct bio_vec *bvec = i->bvec; + size_t skip = i->iov_offset; + size_t size = i->count; + + if ((offset | size) & len_mask) + return false; + do { + size_t len = bvec->bv_len; + + if (len > size) + len = size; + if ((unsigned long)(bvec->bv_offset + skip) & addr_mask) + return false; + bvec++; + size -= len; + skip = 0; + } while (size); + + return true; +} + static void nfs_local_iter_init(struct iov_iter *i, struct nfs_local_kiocb *iocb, int dir) { @@ -346,6 +362,25 @@ nfs_local_iter_init(struct iov_iter *i, struct nfs_local_kiocb *iocb, int dir) hdr->args.count + hdr->args.pgbase); if (hdr->args.pgbase != 0) iov_iter_advance(i, hdr->args.pgbase); + + if (iocb->kiocb.ki_flags & IOCB_DIRECT) { + u32 nf_dio_mem_align, nf_dio_offset_align, nf_dio_read_offset_align; + /* Verify the IO is DIO-aligned as required */ + nfs_to->nfsd_file_dio_alignment(iocb->localio, &nf_dio_mem_align, + &nf_dio_offset_align, + &nf_dio_read_offset_align); + if (dir == READ) + nf_dio_offset_align = nf_dio_read_offset_align; + + if (nf_dio_mem_align && nf_dio_offset_align && + nfs_iov_iter_aligned_bvec(i, hdr->args.offset, + nf_dio_mem_align - 1, + nf_dio_offset_align - 1)) + return; /* is DIO-aligned */ + + /* Fallback to using buffered for this misaligned IO */ + iocb->kiocb.ki_flags &= ~IOCB_DIRECT; + } } static void @@ -406,6 +441,13 @@ nfs_local_read_done(struct nfs_local_kiocb *iocb, long status) struct nfs_pgio_header *hdr = iocb->hdr; struct file *filp = iocb->kiocb.ki_filp; + if (iocb->kiocb.ki_flags & IOCB_DIRECT) { + if (status == -EINVAL) { + /* Underlying FS will return -EINVAL if misaligned DIO is attempted. */ + pr_info_ratelimited("nfs: Unexpected direct I/O read alignment failure\n"); + } + } + nfs_local_pgio_done(hdr, status); /* @@ -598,6 +640,13 @@ nfs_local_write_done(struct nfs_local_kiocb *iocb, long status) dprintk("%s: wrote %ld bytes.\n", __func__, status > 0 ? status : 0); + if (iocb->kiocb.ki_flags & IOCB_DIRECT) { + if (status == -EINVAL) { + /* Underlying FS will return -EINVAL if misaligned DIO is attempted. */ + pr_info_ratelimited("nfs: Unexpected direct I/O write alignment failure\n"); + } + } + /* Handle short writes as if they are ENOSPC */ if (status > 0 && status < hdr->args.count) { hdr->mds_offset += status; diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c index 269fa9391dc46..be710d809a3ba 100644 --- a/fs/nfsd/localio.c +++ b/fs/nfsd/localio.c @@ -117,12 +117,23 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom, return localio; } +static void nfsd_file_dio_alignment(struct nfsd_file *nf, + u32 *nf_dio_mem_align, + u32 *nf_dio_offset_align, + u32 *nf_dio_read_offset_align) +{ + *nf_dio_mem_align = nf->nf_dio_mem_align; + *nf_dio_offset_align = nf->nf_dio_offset_align; + *nf_dio_read_offset_align = nf->nf_dio_read_offset_align; +} + static const struct nfsd_localio_operations nfsd_localio_ops = { .nfsd_net_try_get = nfsd_net_try_get, .nfsd_net_put = nfsd_net_put, .nfsd_open_local_fh = nfsd_open_local_fh, .nfsd_file_put_local = nfsd_file_put_local, .nfsd_file_file = nfsd_file_file, + .nfsd_file_dio_alignment = nfsd_file_dio_alignment, }; void nfsd_localio_ops_init(void) diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h index 59ea90bd136b6..3d91043254e64 100644 --- a/include/linux/nfslocalio.h +++ b/include/linux/nfslocalio.h @@ -64,6 +64,8 @@ struct nfsd_localio_operations { const fmode_t); struct net *(*nfsd_file_put_local)(struct nfsd_file __rcu **); struct file *(*nfsd_file_file)(struct nfsd_file *); + void (*nfsd_file_dio_alignment)(struct nfsd_file *, + u32 *, u32 *, u32 *); } ____cacheline_aligned; extern void nfsd_localio_ops_init(void); -- 2.44.0