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 2B0382135AC for ; Thu, 31 Jul 2025 20:49:27 +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=1753994967; cv=none; b=cPFOYUTHBI5cgZlOb+lc9rIDQC2cj/aua5q2FPFT62XtCuTV0NqJm3Ui2A13IvzZfnPrq8phhJ5ghSkis1K3Wsw4M46lYp7XNI87gv37eZ9LIoQTTx1+7VPdbIoTxnZL9psl9SrwgAsA3j45MdZM9TS1U44eQEVxFWje4KEI6lg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753994967; c=relaxed/simple; bh=lYCWaldKA/oLlOeqhcNXG+Lo2tPLxppDugaRnc28NdM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Bls1knNvGNRgqrLw1YR1l3WlNaFOv0BixmQ7rRcNbnF2kTSIBkLKKAwAcUUqnh4cNo2DQmyc/n/dRVhMb0Q2dV6Zx06H5gsg4xWxOyNQBdfcoiuQUtbzC57f4Ex6q31UGxZZpO6GfXAtcXvUBPLb0jOKL9Esivu4gAaEWIp1LTg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WThTpgfL; 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="WThTpgfL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68260C4CEEF; Thu, 31 Jul 2025 20:49:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753994967; bh=lYCWaldKA/oLlOeqhcNXG+Lo2tPLxppDugaRnc28NdM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WThTpgfLNYRmRyLjUP3ExA/JsD9v/oGnWtpTScliU02Zyj+T7Zd49YkCal45OvHKd bKKU3mgI+YuClv6AYFOsiqQjtMrK6/GcnBRBENHtqB2lGBLl5kDMdcEMIfVMdu+EYK ZXaNsu7Jhj9J6L7byn4d13GjpFaoQTv257aLzkbSUfTOowHv/3MLwggvGZlJum6+pO FxKQn6MKANLsYS8qEU0NxIOiUga6o/R7GMo82zj1vZgn0nf2INfOyBMHREx5DlOwLO m75KcTKsyYea1hAK1jIHrfYifL4FZ5jpf1xB7LsovdkqcDPJWY2pYS9tziV5ZeW0sH uOtrrWrhYTv3Q== Date: Thu, 31 Jul 2025 16:49:25 -0400 From: Mike Snitzer To: Jeff Layton Cc: Chuck Lever , linux-nfs@vger.kernel.org Subject: Re: [PATCH v2 2/4] NFSD: prepare nfsd_vfs_write() to use O_DIRECT on misaligned WRITEs Message-ID: References: <20250731194448.88816-1-snitzer@kernel.org> <20250731194448.88816-3-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Jul 31, 2025 at 04:28:13PM -0400, Jeff Layton wrote: > On Thu, 2025-07-31 at 15:44 -0400, Mike Snitzer wrote: > > Refactor nfsd_vfs_write() to support splitting a WRITE into parts > > (which will be either misaligned or DIO-aligned). Doing so in a > > preliminary commit just allows for indentation and slight > > transformation to be more easily understood and reviewed. > > > > Signed-off-by: Mike Snitzer > > --- > > fs/nfsd/vfs.c | 50 ++++++++++++++++++++++++++++++-------------------- > > 1 file changed, 30 insertions(+), 20 deletions(-) > > > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > > index 35c29b8ade9c3..e4855c32dad12 100644 > > --- a/fs/nfsd/vfs.c > > +++ b/fs/nfsd/vfs.c > > @@ -1341,7 +1341,6 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > struct super_block *sb = file_inode(file)->i_sb; > > struct kiocb kiocb; > > struct svc_export *exp; > > - struct iov_iter iter; > > errseq_t since; > > __be32 nfserr; > > int host_err; > > @@ -1349,6 +1348,9 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > unsigned int pflags = current->flags; > > bool restore_flags = false; > > unsigned int nvecs; > > + struct iov_iter iter_stack[1]; > > + struct iov_iter *iter = iter_stack; > > + unsigned int n_iters = 0; > > > > trace_nfsd_write_opened(rqstp, fhp, offset, *cnt); > > > > @@ -1378,14 +1380,15 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > kiocb.ki_flags |= IOCB_DSYNC; > > > > nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); > > - iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); > > + iov_iter_bvec(&iter[0], ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); > > + n_iters++; > > > > switch (nfsd_io_cache_write) { > > case NFSD_IO_DIRECT: > > /* direct I/O must be aligned to device logical sector size */ > > if (nf->nf_dio_mem_align && nf->nf_dio_offset_align && > > (((offset | *cnt) & (nf->nf_dio_offset_align-1)) == 0) && > > - iov_iter_is_aligned(&iter, nf->nf_dio_mem_align - 1, > > + iov_iter_is_aligned(&iter[0], nf->nf_dio_mem_align - 1, > > nf->nf_dio_offset_align - 1)) > > kiocb.ki_flags = IOCB_DIRECT; > > break; > > @@ -1396,25 +1399,32 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > break; > > } > > > > - since = READ_ONCE(file->f_wb_err); > > - if (verf) > > - nfsd_copy_write_verifier(verf, nn); > > - host_err = vfs_iocb_iter_write(file, &kiocb, &iter); > > - if (host_err < 0) { > > - commit_reset_write_verifier(nn, rqstp, host_err); > > - goto out_nfserr; > > - } > > - *cnt = host_err; > > - nfsd_stats_io_write_add(nn, exp, *cnt); > > - fsnotify_modify(file); > > - host_err = filemap_check_wb_err(file->f_mapping, since); > > - if (host_err < 0) > > - goto out_nfserr; > > + *cnt = 0; > > + for (int i = 0; i < n_iters; i++) { > > + since = READ_ONCE(file->f_wb_err); > > The above assignment can stay outside the loop. No need to resample it > on every pass, and doing that could cause you to miss errors. > > > + if (verf) > > + nfsd_copy_write_verifier(verf, nn); > > > > The verf doesn't need to be copied every time either. OK, ack to both, will fix. > > - if (stable && fhp->fh_use_wgather) { > > - host_err = wait_for_concurrent_writes(file); > > - if (host_err < 0) > > + host_err = vfs_iocb_iter_write(file, &kiocb, &iter[i]); > > + if (host_err < 0) { > > commit_reset_write_verifier(nn, rqstp, host_err); > > + goto out_nfserr; > > + } > > + *cnt += host_err; > > + nfsd_stats_io_write_add(nn, exp, host_err); > > + > > + fsnotify_modify(file); > > + host_err = filemap_check_wb_err(file->f_mapping, since); > > + if (host_err < 0) > > + goto out_nfserr; > > + > > + if (stable && fhp->fh_use_wgather) { > > + host_err = wait_for_concurrent_writes(file); > > + if (host_err < 0) { > > + commit_reset_write_verifier(nn, rqstp, host_err); > > + goto out_nfserr; > > + } > > + } > > } > > > > out_nfserr: > > The rest looks good though. Thanks for the review!