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 E51AC1A256E for ; Fri, 1 Aug 2025 22:29:44 +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=1754087385; cv=none; b=cHu1MrgkeeTKGH9j2SAP1u5+UlqZ2v1RIJGg2hyGhVwX7ZvfR15d70dq5T7IcXV2hQEFYhv7F9XMw5uCBiTFm+bmkqbfuAZISUcOyd6eShyUkqeY03g2eyEyPzEl5P3rW44Bmq2zb0gF5i5ODcT/lGNFc7vvqfjkjXoOmgXyZgk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754087385; c=relaxed/simple; bh=SPP9ELR4Z92PLVrWdPG75YUgIhoA4h8VOau4vMWsMdA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qS3ndQOuW3cveG0r1dp9/6f/J4kGGdJvtHjjJ9X2seb/lbdCVNimd1A6JWr9yIS1ZxGX7YfYcn5T1yOKEHstzNNTaqN4bNCZnm9dgwU+BnqwoB5hqxNPz9zUEZ5DwfM7vQLbbdoMtWUKP6HLB+ekzeiwSxUB/NfO/MwnmiJgLrA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tWouBCVd; 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="tWouBCVd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 445F5C4CEE7; Fri, 1 Aug 2025 22:29:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754087384; bh=SPP9ELR4Z92PLVrWdPG75YUgIhoA4h8VOau4vMWsMdA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tWouBCVd8Lav+EhNlC83SK5EbutrIqUzuP3RTbWPkrtoT2Ujpwqm5Q/v1/4dHarEp lpevrR5RbGDOCt4J6A1ZPf+OpTRQMy619o4yXXj7B3Y/WP3V+KCQlit2rr93qYkQGk gn8x2g+rgc/leL4D0prGjfomEd4F8n1sZOJUmMnV3iKAN9njJelZZiCJ1YElN2rUUq DtEv2WXz0BJ4DC5uUEAbZfiC1mz9xpqUN2l71lIriz9UGXrPF8X9IHzXq7fIVT92JE 5ceVm3H5aecs7G3tpBsqoSqDfY5PoWb2KljZiPUy+xSRCVkRTjB8BaVE+XjVY3gSaT c3cQE5zQXnRWw== Date: Fri, 1 Aug 2025 18:29:43 -0400 From: Mike Snitzer To: Chuck Lever Cc: linux-nfs@vger.kernel.org, Jeff Layton Subject: Re: [PATCH v3 2/4] NFSD: prepare nfsd_vfs_write() to use O_DIRECT on misaligned WRITEs Message-ID: References: <20250731230633.89983-1-snitzer@kernel.org> <20250731230633.89983-3-snitzer@kernel.org> <27aecf85-059f-4789-bcfc-b518a2643e19@oracle.com> 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: <27aecf85-059f-4789-bcfc-b518a2643e19@oracle.com> On Fri, Aug 01, 2025 at 04:52:38PM -0400, Chuck Lever wrote: > On 7/31/25 7:06 PM, 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 > > Reviewed-by: Jeff Layton > > --- > > fs/nfsd/vfs.c | 45 +++++++++++++++++++++++++++------------------ > > 1 file changed, 27 insertions(+), 18 deletions(-) > > > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > > index 35c29b8ade9c3..edac73349da0f 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; > > @@ -1399,22 +1402,28 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > 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; > > - > > - if (stable && fhp->fh_use_wgather) { > > - host_err = wait_for_concurrent_writes(file); > > - if (host_err < 0) > > + *cnt = 0; > > + for (int i = 0; i < n_iters; i++) { > > + 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; > > + } > > Does this loop wait after each iter is written? Would it be better to > wait once after all the iters have been written? It does, sorry about that. This incremental fixes it up and is easily folded into this patch: diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 2eabcb5651ba..1590fc1fb420 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1533,19 +1533,17 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, } *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); + 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) - 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; - } - } + commit_reset_write_verifier(nn, rqstp, host_err); } out_nfserr: