From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 45B9237DAA9 for ; Sun, 5 Jul 2026 14:40:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783262428; cv=none; b=rurO3ANjedVGB/RuYbQaweJbBpk+LSCipietNvoP7AhSKg9ydpNJkacgGAjRgvqSgg6Wl8lpaY/wwscJ6k6tffnAulg2G+WZThyCljdhy8VSvlTiJ2gfkX0TkEjLb60vyljlDC27Q3Tcr3R6F6xlDMMZx9EDwUrMK526cLgH9Y0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783262428; c=relaxed/simple; bh=jS2XdumNaVIUBbJ3VBT9LmBp6rlqyvgUHpNcx52Pba0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XUrOANnDQg2qb2zl5kf2OexgXjrNahqQ6X+lY8y9fxcRZK9c98PdBWzdjoFCT7P46C7613iIN/vXirOnyP7lPZQwCCNMlkkFE1HENe6xNgXfM7r3fefObgRaWdctFu2bT6CNMVqg7I41o2wBJl/4LYFOYi1XyYuSQsXA3WJq5Fs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FF2UOJyd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FF2UOJyd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BFEF1F00A3E; Sun, 5 Jul 2026 14:40:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783262426; bh=pcxN3JEVKE+57r4qQ7Ay7nyfKAR0Au4Vg8C8OAzupn0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FF2UOJydQexG46y0zlmiKM8sHMVBYKkiKvDIeib5+G20hRG2bS3T+DltYAEv0q7Pv H3wkBwcZ7UfG19icds283Ap5tHDbZjoZT7lGmcrynsejXhj3qhRuYqtc7bniLQUYC9 LGK73O9XaLpKlVDeBOjEmLFE9P1VDM9vhmMtLLlUiTPy7iDhhUKyNKugi7dQ26txSv G52OdX8AsrxUF4fXAKr/57tQ7ehmDYB87Ip3HiJlq0baNvHAH4/oTuEz9GHWW2GSBj cMycsDwkf7y9TW9d8yYIZmFvNajINDoLbITHdBcsYK/B45TKE0oDpogtcq5jERrXw5 lTBTexvH12/vQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chris Mason , Chuck Lever , Sasha Levin Subject: [PATCH 6.6.y 2/2] nfsd: reset write verifier on deferred writeback errors Date: Sun, 5 Jul 2026 10:40:23 -0400 Message-ID: <20260705144023.1865360-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260705144023.1865360-1-sashal@kernel.org> References: <2026070203-tipping-straw-267a@gregkh> <20260705144023.1865360-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit 2090b05803faab8a9fa62fbff871007862cac1b7 ] nfsd_vfs_write() and nfsd_commit() both call filemap_check_wb_err() to detect deferred writeback errors, but neither rotates the server's write verifier (nn->writeverf) when this check fails. Every other durable-storage-failure path in these functions calls commit_reset_write_verifier() before returning an error. The missing rotation means clients holding UNSTABLE write data under the current verifier will COMMIT, receive the unchanged verifier back, and conclude their data is durable — silently dropping data that failed writeback. This violates the UNSTABLE+COMMIT durability contract (RFC 1813 §3.3.7, RFC 8881 §18.32). Add commit_reset_write_verifier() calls at both filemap_check_wb_err() error sites, matching the pattern used by adjacent error paths in the same functions. The helper already filters -EAGAIN and -ESTALE internally, so the calls are unconditionally safe. Reported-by: Chris Mason Fixes: 555dbf1a9aac ("nfsd: Replace use of rwsem with errseq_t") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-6 Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/vfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index f83b312fe3b4d4..a37137d722c9e7 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1201,8 +1201,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf, 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) + if (host_err < 0) { + commit_reset_write_verifier(nn, rqstp, host_err); goto out_nfserr; + } if (stable && use_wgather) { host_err = wait_for_concurrent_writes(file); @@ -1344,6 +1346,8 @@ nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf, nfsd_copy_write_verifier(verf, nn); err2 = filemap_check_wb_err(nf->nf_file->f_mapping, since); + if (err2 < 0) + commit_reset_write_verifier(nn, rqstp, err2); err = nfserrno(err2); break; case -EINVAL: -- 2.53.0