From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93C53C27C5E for ; Mon, 10 Jun 2024 03:49:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F64F6B008C; Sun, 9 Jun 2024 23:49:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A5C16B0092; Sun, 9 Jun 2024 23:49:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 06DFE6B0093; Sun, 9 Jun 2024 23:49:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id DCC296B008C for ; Sun, 9 Jun 2024 23:49:45 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 59C70A0B53 for ; Mon, 10 Jun 2024 03:49:45 +0000 (UTC) X-FDA: 82213599930.08.959AFD4 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf19.hostedemail.com (Postfix) with ESMTP id 47BDB1A0005 for ; Mon, 10 Jun 2024 03:49:42 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=a2qTU3O1; spf=none (imf19.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1717991383; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6zeyRcb+UnQLSBhCUqWO1SmkhhrRQveKMeLzcs+rE1w=; b=JAgOtTSz2i4No1MsKamTEEvCrTvVYpd4kA2Yh41HRJeLewhoaXj4AAf1D8IN+kOSvZdRNn s+JLIRB7EFmy7qNMtLc+UMn8FmJtJVfgDhIBKngHUJFpyjnZth3/6wpdKz6NK4yQTLma3Z lhvasdGKum6u6qPyWL82nsrbG7Cul/U= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1717991383; a=rsa-sha256; cv=none; b=1lXIob9YXVSlMOHIY+9S/5+te352rQDjZsvj3sVGQa04JWGGXf2jwPo7c+SpyPqqE1Uofv 7QSHYSnQHuIhcmi7YXluMS/5/0aqHkPoBwJX5bGEIQKlmOwUbSeAUDOos/vISS6nlVICRo RAv72Pal+DFcBVJtWPyoVIDDbT+i4+U= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=a2qTU3O1; spf=none (imf19.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6zeyRcb+UnQLSBhCUqWO1SmkhhrRQveKMeLzcs+rE1w=; b=a2qTU3O1Pc23GUNyvyzjVCt1ec Y2tJDScltfNlQVffSWXcNGqM/WVDJBqakKRd+mP8yrt4lr78r5j4dCZD/lBJxb+LVxWFxNoNIRViC ma6ho/c9uRGiYpoMgYC2rDj3TCK07VZvcVGUwo+OgjWelGHA+IYDy3z4MHbKeux7qVzIQ5AmF3nfh NqM006pjbldpcKzGKNs8sh4DlrMYrACrqF2I92EAS4mceI1vfrIl5YunTvaQZIBZofp423QdzumLa thn+bjPGdtPa9tp0G6pVziIPI+Vg5LtWZfnnx6TenuAdI2bUoYboHup5wD1BqVry3NAfG9rkFJ51+ jQCBYegA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sGW2N-00000008ZAk-395W; Mon, 10 Jun 2024 03:49:39 +0000 Date: Mon, 10 Jun 2024 04:49:39 +0100 From: Matthew Wilcox To: Qu Wenruo Cc: linux-fsdevel@vger.kernel.org, Linux Memory Management List , "linux-btrfs@vger.kernel.org" Subject: Re: The proper handling of failed IO error? Message-ID: References: <960aa841-8d7c-413f-9a1b-0364ae3b9493@gmx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <960aa841-8d7c-413f-9a1b-0364ae3b9493@gmx.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 47BDB1A0005 X-Rspam-User: X-Stat-Signature: ru5orp1wz4abz61i8xqmped8o6b9j9i7 X-HE-Tag: 1717991382-674999 X-HE-Meta: U2FsdGVkX190+LvE6JKH+EIaV5K7ky1rsGGo3VQbQ88uyYa9QCKedwLcePEnmNtXubakqQrXJtbizULy83z7XYu3pQL5l7FRvUjIO0UiMOeLyX1DrhghZl9yEK0YiW3xGmBkUMmxMZuIQRCVDsEyrAQJFryE7scRw06G53yKimjqVPRBkt0Hkc5yD1YrsPnB2uWTkKA+LuBfancEGoyiGsso/Fy5mDSR+VMxpxQKOVUccRPP+GDKdz3b7z2r1GSXeKkmK30/Jdv80cUcLaQGlK6jL1MR7nMne83XKZegz7OzeRvOOR6kccvm304LDd61t0TNrxJc/WIkytd2d+sDdzpH9/89sNPzTZJyEZAVZ8SUV5EurqfFVleBXE3iMOM8JMsrW8y3sqMlsitPhbjOjvzaFVvkZIb6PecldnJkaM/3dqXAMg+72DI/PbOyv/Px0bUf8gziFhrhrbxE7PLArUohyGKH491Bb3/VEcEtpOVUWPkntXYEWCQRrrpMBvsGWb6hfYNPuPhoVPVzOHyoD3D6O5hSj+Qq5FVtdDvETmVwiw/G9GJnkcSJ2FIkkrAe1YAvTLEoOA6gPgbUT26YFruVwParUrOkuOeHeShgAQ3sx1KJC5dhQJjnOIuFjuQCkjFUmSTu/LHN4sleyuZTQa29ykLoAQs7VrQ5/30RgmKR+6RHa4fnLEDhvXYvvjYhtjf2dCq48SmFCAm3pNLiSJoliz3asfgiYWnN90Z9c0j5YIN32IOzlu8bC4R6uemv4L4KXpNDCBXIfHk9hQSm5c8rY1OYaOZmy4SGGROCwmjsuN9lSpqc7Uviyv2lbV409aD0M7HmQVGfcfbOE+x5oVHdrmNscAK7YCklQdypGTH5UsyNNR6Q3jIR6n8I5iq5NO9dIDwxtAfSo1Jn5WXZlQ++2lF9XmFgdRICC7i76VLZBB43RKd6XTHYwfOUSCeJGYZrrz3/NrJ2pklEPzS rPIZd8ro GbeuTAqXOZ2Td4zXmCXouwbF3d8TQbGxl6bvd+W2KgoZJTAK5sECkejZG4EqqurIPYqRExk3UOABAmwps4c5IHP5A0Faz4Qg4YW/kSg6ZUJhgwkBriOzR8pyOHWQ4fyfs18w3EaFsgQfhH5hNAAaQ7VMwzFwTx/380c1SGPSdgvW6GNL/hDw0HQf7shnCpB+ARCqflJhyH264MATxRpnVSsMhof17Pp1fSzv7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 10, 2024 at 06:50:11AM +0930, Qu Wenruo wrote: > Hi, > > There is a recent (well a year ago) change in btrfs to remove the usage > of page/folio error, which gets me wondering what would happen if we got > a lot of write errors and high memory pressure? > > Yes, all file systems calls mapping_set_error() so that fsync call would > return error, but I'm wondering what would happen to those folios that > failed to be written? > > Those folios has their DIRTY flag cleared before submission, and and > their endio functions, the WRITEBACK flags is also cleared. > > Meaning after such write failure, the page/folio has UPTODATE flag, and > no DIRTY/ERROR/WRITEBACK flags (at least for btrfs and ext4, meanwhile > iomap still set the ERROR flag). > > Would any memory pressure just reclaim those pages/folios without them > really reaching the disk? Yes. Core code doesn't (and hasn't in some time) checked the page/folio error flag. That's why it's being removed. Also, btrfs was using it incorrectly to indicate a write error. It was supposed to be used for read errors, not write errors. Another good reason to remove it.