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 A7A8A25767; Thu, 7 Mar 2024 12:30:16 +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=1709814616; cv=none; b=qn+igGtjob6alRt6oqPddbrKWunCpcXd27xqJx5UXg/VyC08m79GrlrLt1hdGK6p+0efJy7NX8oYcTntzBTka6ajRDNVUUUfrJ1ohk8GBLkXk6EzAs4qLUeixaU8pKnV5/rX3xb4/gTzXlw901RfimDLIklzhySM1hf/JMpB5E0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709814616; c=relaxed/simple; bh=rDREcHbUEOzK/GRMRvP1rJ34opqMAk4QFuEjuF/UFz0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=CuR3nodzzeR/EdA7wCt8wKs6U6Mg/0Stnfbz6leZ4QZGVcO7E+wkgZA8k7X061zwLjrPZ9fDaqZFXlzWVjPGtE8rpGB2eV0uCtpW08FV8pUDPeyZnoxIfdEdaB13Wi8aJ+51PWA8mKDCA0AnQLmCBItupCZANS7BV3TRksscHr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KEV7sem3; 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="KEV7sem3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF29DC43394; Thu, 7 Mar 2024 12:30:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709814616; bh=rDREcHbUEOzK/GRMRvP1rJ34opqMAk4QFuEjuF/UFz0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=KEV7sem3uj1du8/q8zQyNfD6WMPH4KOhot9VPJZWoEgngnHdEilntaX8A9O366AtM wYPkCvr0AAzUdivTWporCO9gQ3PF49+BiPw52fRh/F3IVLRgT0iufeYK805/0qizau 8POyBzH/WzCVn+tgfFoCYBdl2lp3wV7ClMVf141MVIyRUL2LEx/4kVffo6II6FVxII vFyg3k3zbxEaymwEzzfrgc/9jhDShNvKqdCHJ/3d1cJyQeoBX5k9E3wF4oAKjk1+6W IbG5SccxiJD/fxoG9vpVHo73HmfvEtuSSKbw2dwqHbisQpvKnt1q/ALobQ+96VL6NP nQ+USdrv2xsdw== Message-ID: <9e8223c289a4d05cdbbb21c79e5a2439e2dcb5b1.camel@kernel.org> Subject: Re: [PATCH stable 6.6 and 6.7] NFS: Fix data corruption caused by congestion. From: Jeff Layton To: NeilBrown Cc: stable@vger.kernel.org, Trond Myklebust , Anna Schumaker , linux-nfs@vger.kernel.org, Dan Aloni Date: Thu, 07 Mar 2024 12:30:14 +0000 In-Reply-To: <170981170160.13576.347273159851012933@noble.neil.brown.name> References: <170907621128.24797.4390391329078744015@noble.neil.brown.name> , <170981170160.13576.347273159851012933@noble.neil.brown.name> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; 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QiErRVPpB7VzA/pYV5Mdy7GMbPjmO0IpoL0tVZ8JvUzUZXB3ErS/dJflvboAAQeLpLCkQjqZiQ/DCmgJCrBJst9Xc7YsKKS379Tc3GU33HNSpaOxs2NwfzoesyjKU+P35czvXWTtj7KVVSj3SgzzFk+gLx8y2Nvt9iESdZ1Ustv8tipDsGcvIZ43MQwqU9YbLg8k4V9ch+Mo8SE+C0jyZYDCE2ZGf3OztvtSYMsTnF6/luzVyej1AFVYjKHORzNoTwdHUeC+9/07GO0bMYTPXYvJ/vxBFm3oniXyhgb5FtABEBAAGJAh8EGAECAAkFAk6V0TwCGwwACgkQAA5oQRlWghXhZRAAyycZ2DDyXh2bMYvI8uHgCbeXfL3QCvcw2XoZTH2l2umPiTzrCsDJhgwZfG9BDyOHaYhPasd5qgrUBtjjUiNKjVM+Cx1DnieR0dZWafnqGv682avPblfi70XXr2juRE/fSZoZkyZhm+nsLuIcXTnzY4D572JGrpRMTpNpGmitBdh1l/9O7Fb64uLOtA5Qj5jcHHOjL0DZpjmFWYKlSAHmURHrE8M0qRryQXvlhoQxlJR4nvQrjOPMsqWD5F9mcRyowOzr8amasLv43w92rD2nHoBK6rbFE/qC7AAjABEsZq8+TQmueN0maIXUQu7TBzejsEbV0i29z+kkrjU2NmK5pcxgAtehVxpZJ14LqmN6E0suTtzjNT1eMoqOPrMSx+6vOCIuvJ/MVYnQgHhjtPPnU86mebTY5Loy9YfJAC2EVpxtcCbx2KiwErTndEyWL+GL53LuScUD7tW8vYbGIp4RlnUgPLbqpgssq2gwYO9m75FGuKuB2+2bCGajqalid5nzeq9v7cYLLRgArJfOIBWZrHy2m0C+pFu9DSuV6SNr2dvMQUv1V58h0FaSOxHVQnJdnoHn13g/CKKvyg2EMrMt/EfcXgvDwQbnG9we4xJiWOIOcsvrWcB6C6lWBDA+In7w7SXnnok kZWuOsJdJQdmwlWC5L5ln9xgfr/4mOY38B0U= Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.4 (3.50.4-1.fc39) Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2024-03-07 at 22:41 +1100, NeilBrown wrote: > On Thu, 07 Mar 2024, Jeff Layton wrote: > > On Wed, 2024-02-28 at 10:23 +1100, NeilBrown wrote: > > > when AOP_WRITEPAGE_ACTIVATE is returned (as NFS does when it detects > > > congestion) it is important that the folio is redirtied. > > > nfs_writepage_locked() doesn't do this, so files can become corrupted= as > > > writes can be lost. > > >=20 > > > Note that this is not needed in v6.8 as AOP_WRITEPAGE_ACTIVATE cannot= be > > > returned. It is needed for kernels v5.18..v6.7. Prior to 6.3 the pa= tch > > > is different as it needs to mention "page", not "folio". > > >=20 > >=20 > > Neil, I have a question about the above statement. In Linus's tree as o= f > > this morning (v6.8-rc7-ish), it does this in nfs_writepages_locked: > >=20 > > if (wbc->sync_mode =3D=3D WB_SYNC_NONE && > > NFS_SERVER(inode)->write_congested) =20 > > return AOP_WRITEPAGE_ACTIVATE; > >=20 > > The only caller of nfs_writepages_locked, and I don't see where it > > redirties the page. Why don't we need this in v6.8? >=20 > You are right - it doesn't redirty anything. But there is no bug > here.... > I didn't see it at first either, but the only caller of > nfs_writepage_locked() is nfs_wb_folio() (as you say) and that always > passes a wbc with .sync_mode =3D WB_SYNC_ALL. So sync_mode is never > WB_SYNC_NODE and the code snippet you included above is dead code. I've > already posted a patch to Trond and Anna to remove that code. >=20 > Thanks for the review! >=20 Thanks Neil, I missed that bit about the sync_mode. I sent a R-b for your other patch too. Cheers, Jeff > >=20 > >=20 > > > Reported-and-tested-by: Jacek Tomaka > > > Fixes: 6df25e58532b ("nfs: remove reliance on bdi congestion") > > > Signed-off-by: NeilBrown > > > --- > > > fs/nfs/write.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > >=20 > > > diff --git a/fs/nfs/write.c b/fs/nfs/write.c > > > index b664caea8b4e..9e345d3c305a 100644 > > > --- a/fs/nfs/write.c > > > +++ b/fs/nfs/write.c > > > @@ -668,8 +668,10 @@ static int nfs_writepage_locked(struct folio *fo= lio, > > > int err; > > > =20 > > > if (wbc->sync_mode =3D=3D WB_SYNC_NONE && > > > - NFS_SERVER(inode)->write_congested) > > > + NFS_SERVER(inode)->write_congested) { > > > + folio_redirty_for_writepage(wbc, folio); > > > return AOP_WRITEPAGE_ACTIVATE; > > > + } > > > =20 > > > nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE); > > > nfs_pageio_init_write(&pgio, inode, 0, false, > >=20 > > --=20 > > Jeff Layton > >=20 >=20 --=20 Jeff Layton