From nobody Sun Feb 8 18:56:34 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1667329323; cv=none; d=zohomail.com; s=zohoarc; b=iQ+QByjcSxR6XAf0ppTN48nAH9F3WrYzqPTkZLQQ3eAESuLeM0yPje9JwPtCVXXexvHQCoWp1UIwFHXpltihyY3UUTHpcJyONYpDjykGV/j9dFyyMNBl5kgzkVumrUyTEpIK5/6ooWfm/mGIptRjRIDekKuDD09v6udefkKK+8s= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1667329323; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=NLagzt3b9eFE5VQap6yM2xzJT792otpID4qDi8KriWE=; b=V8EbO7dIwXBhZKjS6i0Lp2DoF2Yvd1LSX3SdP47Vqku9LDTss6OC6q2Pk5nnzJ6oJ3ETYhKHkZNH4+YvfGgbu+e485wyEUGwMqAU2AoJUbZFX982Oo2PHmkeVIiB6ui0FRXD9oyTfKqXww1HF/3VTWYm/2N2/TUIsUGaigkraPs= ARC-Authentication-Results: i=1; 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bh=NLagzt3b9eFE5VQap6yM2xzJT792otpID4qDi8KriWE=; b=B+RuLre0Z3tWReLKDbwrP9eb/Vu+P3pSjPk1qq4qargCJ7ZBqJCjt+ft6MzqGWMQszD8SY Ask9P361FqqNXvIKDIk623sl5fiaM1X6oEc8zqP4uNsrEstn43vSW3RxFBjKlxQ3d1YfOO c/34I6O4TELNv6d37+rCIvXF0SqUhKs= X-MC-Unique: 8Ks1pwd6ON69v6pwij917Q-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: hreitz@redhat.com, qemu-block@nongnu.org, Kevin Wolf , nsoffer@redhat.com, Stefan Hajnoczi Subject: [PATCH 1/2] file-posix: fix Linux alignment probing when EIO is returned Date: Tue, 1 Nov 2022 15:00:30 -0400 Message-Id: <20221101190031.6766-2-stefanha@redhat.com> In-Reply-To: <20221101190031.6766-1-stefanha@redhat.com> References: <20221101190031.6766-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.051, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1667329325056100005 Content-Type: text/plain; charset="utf-8" Linux dm-crypt returns errno EIO from unaligned O_DIRECT pread(2) calls. Alignment probing fails on dm-crypt devices because the code expects EINVAL. Treating any errno as an "unaligned" indicator would be easy, but breaks commit 22d182e82b4b ("block/raw-posix: fix launching with failed disks"). Offline disks return EIO for correctly aligned requests and EINVAL for unaligned requests. It's possible to make both dm-crypt and offline disks work: look for the transition from EINVAL to EIO instead of for a single EINVAL value. Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1290 Fixes: 22d182e82b4b ("block/raw-posix: fix launching with failed disks") Signed-off-by: Stefan Hajnoczi --- block/file-posix.c | 42 +++++++++++++++--------------------------- 1 file changed, 15 insertions(+), 27 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index b9647c5ffc..b9d62f52fe 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -355,31 +355,6 @@ static bool raw_needs_alignment(BlockDriverState *bs) return s->force_alignment; } =20 -/* Check if read is allowed with given memory buffer and length. - * - * This function is used to check O_DIRECT memory buffer and request align= ment. - */ -static bool raw_is_io_aligned(int fd, void *buf, size_t len) -{ - ssize_t ret =3D pread(fd, buf, len, 0); - - if (ret >=3D 0) { - return true; - } - -#ifdef __linux__ - /* The Linux kernel returns EINVAL for misaligned O_DIRECT reads. Ign= ore - * other errors (e.g. real I/O error), which could happen on a failed - * drive, since we only care about probing alignment. - */ - if (errno !=3D EINVAL) { - return true; - } -#endif - - return false; -} - static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) { BDRVRawState *s =3D bs->opaque; @@ -426,34 +401,47 @@ static void raw_probe_alignment(BlockDriverState *bs,= int fd, Error **errp) * try to detect buf_align, which cannot be detected in some cases (e.= g. * Gluster). If buf_align cannot be detected, we fallback to the value= of * request_alignment. + * + * The probing loop keeps track of the last errno so that the alignmen= t of + * offline disks can be probed. On Linux pread(2) returns with errno E= INVAL + * for most file descriptors when O_DIRECT alignment constraints are u= nmet. + * Offline disks fail correctly aligned pread(2) with EIO. Therefore i= t's + * possible to detect alignment on offline disks by observing when the + * errno changes from EINVAL to something else. */ =20 if (!bs->bl.request_alignment) { + int last_errno =3D 0; int i; size_t align; buf =3D qemu_memalign(max_align, max_align); for (i =3D 0; i < ARRAY_SIZE(alignments); i++) { align =3D alignments[i]; - if (raw_is_io_aligned(fd, buf, align)) { + if (pread(fd, buf, align, 0) >=3D 0 || + (errno !=3D EINVAL && last_errno =3D=3D EINVAL)) { /* Fallback to safe value. */ bs->bl.request_alignment =3D (align !=3D 1) ? align : max_= align; break; } + last_errno =3D errno; } qemu_vfree(buf); } =20 if (!s->buf_align) { + int last_errno =3D 0; int i; size_t align; buf =3D qemu_memalign(max_align, 2 * max_align); for (i =3D 0; i < ARRAY_SIZE(alignments); i++) { align =3D alignments[i]; - if (raw_is_io_aligned(fd, buf + align, max_align)) { + if (pread(fd, buf + align, max_align, 0) >=3D 0 || + (errno !=3D EINVAL && last_errno =3D=3D EINVAL)) { /* Fallback to request_alignment. */ s->buf_align =3D (align !=3D 1) ? align : bs->bl.request_a= lignment; break; } + last_errno =3D errno; } qemu_vfree(buf); } --=20 2.38.1 From nobody Sun Feb 8 18:56:34 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1667329323; cv=none; d=zohomail.com; s=zohoarc; b=cOIF+eHqlgaJz1LgaASbMQnE8mjqqMvNXwwFA5bfLCECEO2lgFy74izZ7accXkTn3zCEflZw/38yrm8l3dbJtdqJVO4rNc/oOgyGiOO0gSvERqqI5cwQnCch3sPlADIQuKFUXdkqng92/xTczKKae/EnV8A86BUjxhgwCr+Xp0o= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1667329323; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=5VS4xrxKb46L8wD9rGlnnrigI463dvsqve/1eQSqxrQ=; b=GL9jMwDBylUJSz/TLfAPhFtacPepKlXnv2HLZEJgVuZzEMuO7sfPS/A0R/Y3VvPI7XdmTD4lT5dkTSEjPWP1I0oyAynzLRociJu/dhVHRLfJVg9iPybHq6LKwBXBcf1VfsPzOHsT/lVHY+dTB3E6RLcQNlEmscBMyJKWkh1AUrQ= ARC-Authentication-Results: i=1; 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Tue, 01 Nov 2022 15:01:01 -0400 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-629-RhOggFYzM5uOSmiok3FsfA-1; Tue, 01 Nov 2022 15:00:52 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CE53A101A5C0; Tue, 1 Nov 2022 19:00:51 +0000 (UTC) Received: from localhost (unknown [10.39.192.93]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4FAF740C945A; Tue, 1 Nov 2022 19:00:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667329255; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5VS4xrxKb46L8wD9rGlnnrigI463dvsqve/1eQSqxrQ=; b=ijx4GIwmAd+K2hevPmmWZ4lK6UjFHnMZkhYgvm4xwY4r/3JCatIyoPZmkgq/DqT3YB32+V PGic6YHxZE15Na3xCkR3zr+DfGqWVSRP8VDv9ItOXjcWybDQdhNyJKfKOIdu1Ul0FjFhrY omvDTcAOpd6x9TYedAVAiAAEwwMKMLw= X-MC-Unique: RhOggFYzM5uOSmiok3FsfA-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: hreitz@redhat.com, qemu-block@nongnu.org, Kevin Wolf , nsoffer@redhat.com, Stefan Hajnoczi , Eric Biggers Subject: [PATCH 2/2] file-posix: add statx(STATX_DIOALIGN) support Date: Tue, 1 Nov 2022 15:00:31 -0400 Message-Id: <20221101190031.6766-3-stefanha@redhat.com> In-Reply-To: <20221101190031.6766-1-stefanha@redhat.com> References: <20221101190031.6766-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1667329325063100006 Content-Type: text/plain; charset="utf-8" Linux commit 825cf206ed51 ("statx: add direct I/O alignment information") added an interface to fetch O_DIRECT alignment values for block devices and file systems. Prefer STATX_DIOALIGN to older interfaces and probing, but keep them as fallbacks in case STATX_DIOALIGN cannot provide the information. Testing shows the status of STATX_DIOALIGN support in Linux 6.1-rc3 appears to be: - btrfs: no - ext4: yes - XFS: yes - NVMe block devices: yes - dm-crypt: yes Cc: Eric Biggers Signed-off-by: Stefan Hajnoczi --- block/file-posix.c | 54 +++++++++++++++++++++++++++++++--------------- 1 file changed, 37 insertions(+), 17 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index b9d62f52fe..00d8191880 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -372,28 +372,48 @@ static void raw_probe_alignment(BlockDriverState *bs,= int fd, Error **errp) =20 bs->bl.request_alignment =3D 0; s->buf_align =3D 0; + +#if defined(__linux__) && defined(STATX_DIOALIGN) + struct statx stx; + + /* + * Linux 6.1 introduced an interface for both block devices and file + * systems. The system call returns with the STATX_DIOALIGN bit cleared + * when the information is unavailable. + */ + if (statx(fd, "", AT_EMPTY_PATH, STATX_DIOALIGN, &stx) =3D=3D 0 && + (stx.stx_mask & STATX_DIOALIGN)) { + bs->bl.request_alignment =3D stx.stx_dio_offset_align; + s->buf_align =3D stx.stx_dio_mem_align; + } +#endif /* defined(__linux__) && defined(STATX_DIOALIGN) */ + /* Let's try to use the logical blocksize for the alignment. */ - if (probe_logical_blocksize(fd, &bs->bl.request_alignment) < 0) { - bs->bl.request_alignment =3D 0; + if (!bs->bl.request_alignment) { + if (probe_logical_blocksize(fd, &bs->bl.request_alignment) < 0) { + bs->bl.request_alignment =3D 0; + } } =20 #ifdef __linux__ - /* - * The XFS ioctl definitions are shipped in extra packages that might - * not always be available. Since we just need the XFS_IOC_DIOINFO ioc= tl - * here, we simply use our own definition instead: - */ - struct xfs_dioattr { - uint32_t d_mem; - uint32_t d_miniosz; - uint32_t d_maxiosz; - } da; - if (ioctl(fd, _IOR('X', 30, struct xfs_dioattr), &da) >=3D 0) { - bs->bl.request_alignment =3D da.d_miniosz; - /* The kernel returns wrong information for d_mem */ - /* s->buf_align =3D da.d_mem; */ + if (!bs->bl.request_alignment) { + /* + * The XFS ioctl definitions are shipped in extra packages that mi= ght + * not always be available. Since we just need the XFS_IOC_DIOINFO= ioctl + * here, we simply use our own definition instead: + */ + struct xfs_dioattr { + uint32_t d_mem; + uint32_t d_miniosz; + uint32_t d_maxiosz; + } da; + if (ioctl(fd, _IOR('X', 30, struct xfs_dioattr), &da) >=3D 0) { + bs->bl.request_alignment =3D da.d_miniosz; + /* The kernel returns wrong information for d_mem */ + /* s->buf_align =3D da.d_mem; */ + } } -#endif +#endif /* __linux__ */ =20 /* * If we could not get the sizes so far, we can only guess them. First= try --=20 2.38.1