From nobody Wed Oct 23 01:38:53 2024 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=linaro.org ARC-Seal: i=1; a=rsa-sha256; t=1728988968; cv=none; d=zohomail.com; s=zohoarc; b=ilbqD0v2d9GTM8yMKwg/lafMZ2wsm8ftwSgA/d8CXqTgY+i6Zg73drSjOmlc1AAzHF+Dk679qOTkfN4tcRydfNGdoLwqtEb3+UyGzqtBkAkGriSKkIBqd9NRZwJKofX6bV3/hkAGOkUa7615S+N5JH/jojEeialfIa7RmbuzKvw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1728988968; h=Content-Transfer-Encoding:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To:Cc; bh=AAgujXpX2gYXqhZkrhcPFNZmS/QvAosO9xPCDtYgfm8=; b=jmLsaxnQ1xpW0AhQo6dYsz6SV01b0x/VmUEVmPu117AbUkr6FJLZXgUNSPehCroaKIleJIBbVTdck10xI2GVTByFlWuZwbwvEh4EDjIEeGinisnaMGQCoXsqTz00PfSM/anmA/zbaOwxqy6qDuY6MpZ6lqz0E42UTE15X+rSBPA= ARC-Authentication-Results: i=1; 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 header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1728988968498236.6741933331068; Tue, 15 Oct 2024 03:42:48 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t0ewt-0006kP-Cn; Tue, 15 Oct 2024 06:38:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t0ewY-0006gO-Fm for qemu-devel@nongnu.org; Tue, 15 Oct 2024 06:38:22 -0400 Received: from mail-wr1-x42e.google.com ([2a00:1450:4864:20::42e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1t0ewU-0005xB-AD for qemu-devel@nongnu.org; Tue, 15 Oct 2024 06:38:22 -0400 Received: by mail-wr1-x42e.google.com with SMTP id ffacd0b85a97d-37d538fe5f2so2931360f8f.2 for ; Tue, 15 Oct 2024 03:38:17 -0700 (PDT) Received: from orth.archaic.org.uk (orth.archaic.org.uk. [2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d7fa7a06dsm1241635f8f.5.2024.10.15.03.38.16 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Oct 2024 03:38:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1728988697; x=1729593497; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=AAgujXpX2gYXqhZkrhcPFNZmS/QvAosO9xPCDtYgfm8=; b=FdHsd/3q9jBbc3Qp55DRokEl+A+1haycYJcdMd0hvrT/9iqpFRO2zL36uT2JSLpNzg oUwsEkjbtBbCK3W6FbbGi385ZQ+45MC/VIi5aLC4HdS6533hTKi/RZEkMNCebHP1CQqV VIExRibA/agypO2YaN74K4/rGdz55/Bjk/maIzVsj2q1uqt9c4Sm+874zakERsVILnYe JxNTDoIJnKQSzcoDFCFF3O4yhJIWQS59Y5PPz7Xwz5yKIV99UvR8BvNxcMFn9PbP8mXZ 61pgq1v+OxBrufjlKxaj+rwp6J92OQxIu8RAAv4f6/z160c7uQQgg48unPrVhagSg+vE 9+Ig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728988697; x=1729593497; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=AAgujXpX2gYXqhZkrhcPFNZmS/QvAosO9xPCDtYgfm8=; b=sFHPfpRIeYLVh130VarBwQnQpM8p5QTbGfpVSxQSeXrXiJopzoYtVc54pdkDDRWE86 +YURQCqTW4+DMx4K3UWqfafj8zOYXJ0NYfZpe8F7IOzBsdiux6Il3Hgc94tAh5HCsMtP kNQ1f7HAOBalJu41DkwdMb1uXh+DACNSPnU3V+HUsCaEM1tmfcp03Qh8cKSac+2BBdgD AaHQGgaDNJvSxvTxNUiYzO0W0xSaFHw+SPofmiSZx0fj90B5Q8FbuaXogEzAL1T3NQVt kpxk3cavwLvJbtwco6OYK3KYEOhBA5E8EjT4QwX//k35wc5lmXqEWEhQk4dxC7VHbqE9 hlFA== X-Gm-Message-State: AOJu0Ywoj6x1gzIAg3jZDEentolRgiISqHvMyIniC/xJR1TbeuFQMFsW CWbY/PxjbXZdg9zajIUGk3Ob4AQ63uppcc9v5k5ljEjL96ttihuzaIpGvLUO78Shu5NUShXgb1F f X-Google-Smtp-Source: AGHT+IEljiPYfmWT/bWi9PQZVOIrbMnOVeVabN+jsufU2FUX/MXARpI6/y5PFnh7MsC2JD0+qapffQ== X-Received: by 2002:adf:e88b:0:b0:37d:4cd6:6f2b with SMTP id ffacd0b85a97d-37d551d2566mr8846389f8f.14.1728988696492; Tue, 15 Oct 2024 03:38:16 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PULL 14/28] docs/devel/blkdebug: Convert to rST format Date: Tue, 15 Oct 2024 11:37:54 +0100 Message-Id: <20241015103808.133024-15-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241015103808.133024-1-peter.maydell@linaro.org> References: <20241015103808.133024-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=2a00:1450:4864:20::42e; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x42e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1728988969325116600 Content-Type: text/plain; charset="utf-8" Convert blkdebug.txt to rST format. We put it into index-build.rst because it falls under the "test" part of "QEMU Build and Test System". Signed-off-by: Peter Maydell Reviewed-by: Thomas Huth Message-id: 20240816132212.3602106-2-peter.maydell@linaro.org --- MAINTAINERS | 1 + docs/devel/blkdebug.txt | 162 ----------------------------- docs/devel/testing/blkdebug.rst | 177 ++++++++++++++++++++++++++++++++ docs/devel/testing/index.rst | 1 + 4 files changed, 179 insertions(+), 162 deletions(-) delete mode 100644 docs/devel/blkdebug.txt create mode 100644 docs/devel/testing/blkdebug.rst diff --git a/MAINTAINERS b/MAINTAINERS index 5cd661c9f9d..d4eb221b88c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3967,6 +3967,7 @@ M: Hanna Reitz L: qemu-block@nongnu.org S: Supported F: block/blkdebug.c +F: docs/devel/blkdebug.rst =20 vpc M: Kevin Wolf diff --git a/docs/devel/blkdebug.txt b/docs/devel/blkdebug.txt deleted file mode 100644 index 0b0c128d356..00000000000 --- a/docs/devel/blkdebug.txt +++ /dev/null @@ -1,162 +0,0 @@ -Block I/O error injection using blkdebug ----------------------------------------- -Copyright (C) 2014-2015 Red Hat Inc - -This work is licensed under the terms of the GNU GPL, version 2 or later. = See -the COPYING file in the top-level directory. - -The blkdebug block driver is a rule-based error injection engine. It can = be -used to exercise error code paths in block drivers including ENOSPC (out of -space) and EIO. - -This document gives an overview of the features available in blkdebug. - -Background ----------- -Block drivers have many error code paths that handle I/O errors. Image fo= rmats -are especially complex since metadata I/O errors during cluster allocation= or -while updating tables happen halfway through request processing and require -discipline to keep image files consistent. - -Error injection allows test cases to trigger I/O errors at specific points. -This way, all error paths can be tested to make sure they are correct. - -Rules ------ -The blkdebug block driver takes a list of "rules" that tell the error inje= ction -engine when to fail an I/O request. - -Each I/O request is evaluated against the rules. If a rule matches the re= quest -then its "action" is executed. - -Rules can be placed in a configuration file; the configuration file -follows the same .ini-like format used by QEMU's -readconfig option, and -each section of the file represents a rule. - -The following configuration file defines a single rule: - - $ cat blkdebug.conf - [inject-error] - event =3D "read_aio" - errno =3D "28" - -This rule fails all aio read requests with ENOSPC (28). Note that the err= no -value depends on the host. On Linux, see -/usr/include/asm-generic/errno-base.h for errno values. - -Invoke QEMU as follows: - - $ qemu-system-x86_64 - -drive if=3Dnone,cache=3Dnone,file=3Dblkdebug:blkdebug.conf:test.i= mg,id=3Ddrive0 \ - -device virtio-blk-pci,drive=3Ddrive0,id=3Dvirtio-blk-pci0 - -Rules support the following attributes: - - event - which type of operation to match (e.g. read_aio, write_aio, - flush_to_os, flush_to_disk). See the "Events" section for - information on events. - - state - (optional) the engine must be in this state number in order for = this - rule to match. See the "State transitions" section for informat= ion - on states. - - errno - the numeric errno value to return when a request matches this ru= le. - The errno values depend on the host since the numeric values are= not - standardized in the POSIX specification. - - sector - (optional) a sector number that the request must overlap in ord= er to - match this rule - - once - (optional, default "off") only execute this action on the first - matching request - - immediately - (optional, default "off") return a NULL BlockAIOCB - pointer and fail without an errno instead. This - exercises the code path where BlockAIOCB fails and the - caller's BlockCompletionFunc is not invoked. - -Events ------- -Block drivers provide information about the type of I/O request they are a= bout -to make so rules can match specific types of requests. For example, the q= cow2 -block driver tells blkdebug when it accesses the L1 table so rules can mat= ch -only L1 table accesses and not other metadata or guest data requests. - -The core events are: - - read_aio - guest data read - - write_aio - guest data write - - flush_to_os - write out unwritten block driver state (e.g. cached metada= ta) - - flush_to_disk - flush the host block device's disk cache - -See qapi/block-core.json:BlkdebugEvent for the full list of events. -You may need to grep block driver source code to understand the -meaning of specific events. - -State transitions ------------------ -There are cases where more power is needed to match a particular I/O reque= st in -a longer sequence of requests. For example: - - write_aio - flush_to_disk - write_aio - -How do we match the 2nd write_aio but not the first? This is where state -transitions come in. - -The error injection engine has an integer called the "state" that always s= tarts -initialized to 1. The state integer is internal to blkdebug and cannot be -observed from outside but rules can interact with it for powerful matching -behavior. - -Rules can be conditional on the current state and they can transition to a= new -state. - -When a rule's "state" attribute is non-zero then the current state must eq= ual -the attribute in order for the rule to match. - -For example, to match the 2nd write_aio: - - [set-state] - event =3D "write_aio" - state =3D "1" - new_state =3D "2" - - [inject-error] - event =3D "write_aio" - state =3D "2" - errno =3D "5" - -The first write_aio request matches the set-state rule and transitions from -state 1 to state 2. Once state 2 has been entered, the set-state rule no -longer matches since it requires state 1. But the inject-error rule now -matches the next write_aio request and injects EIO (5). - -State transition rules support the following attributes: - - event - which type of operation to match (e.g. read_aio, write_aio, - flush_to_os, flush_to_disk). See the "Events" section for - information on events. - - state - (optional) the engine must be in this state number in order for = this - rule to match - - new_state - transition to this state number - -Suspend and resume ------------------- -Exercising code paths in block drivers may require specific ordering among= st -concurrent requests. The "breakpoint" feature allows requests to be halte= d on -a blkdebug event and resumed later. This makes it possible to achieve -deterministic ordering when multiple requests are in flight. - -Breakpoints on blkdebug events are associated with a user-defined "tag" st= ring. -This tag serves as an identifier by which the request can be resumed at a = later -point. - -See the qemu-io(1) break, resume, remove_break, and wait_break commands for -details. diff --git a/docs/devel/testing/blkdebug.rst b/docs/devel/testing/blkdebug.= rst new file mode 100644 index 00000000000..63887c9aa9c --- /dev/null +++ b/docs/devel/testing/blkdebug.rst @@ -0,0 +1,177 @@ +Block I/O error injection using ``blkdebug`` +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +.. + Copyright (C) 2014-2015 Red Hat Inc + + This work is licensed under the terms of the GNU GPL, version 2 or late= r. See + the COPYING file in the top-level directory. + +The ``blkdebug`` block driver is a rule-based error injection engine. It = can be +used to exercise error code paths in block drivers including ``ENOSPC`` (o= ut of +space) and ``EIO``. + +This document gives an overview of the features available in ``blkdebug``. + +Background +---------- +Block drivers have many error code paths that handle I/O errors. Image fo= rmats +are especially complex since metadata I/O errors during cluster allocation= or +while updating tables happen halfway through request processing and require +discipline to keep image files consistent. + +Error injection allows test cases to trigger I/O errors at specific points. +This way, all error paths can be tested to make sure they are correct. + +Rules +----- +The ``blkdebug`` block driver takes a list of "rules" that tell the error = injection +engine when to fail an I/O request. + +Each I/O request is evaluated against the rules. If a rule matches the re= quest +then its "action" is executed. + +Rules can be placed in a configuration file; the configuration file +follows the same .ini-like format used by QEMU's ``-readconfig`` option, a= nd +each section of the file represents a rule. + +The following configuration file defines a single rule:: + + $ cat blkdebug.conf + [inject-error] + event =3D "read_aio" + errno =3D "28" + +This rule fails all aio read requests with ``ENOSPC`` (28). Note that the= errno +value depends on the host. On Linux, see +``/usr/include/asm-generic/errno-base.h`` for errno values. + +Invoke QEMU as follows:: + + $ qemu-system-x86_64 + -drive if=3Dnone,cache=3Dnone,file=3Dblkdebug:blkdebug.conf:test.i= mg,id=3Ddrive0 \ + -device virtio-blk-pci,drive=3Ddrive0,id=3Dvirtio-blk-pci0 + +Rules support the following attributes: + +``event`` + which type of operation to match (e.g. ``read_aio``, ``write_aio``, + ``flush_to_os``, ``flush_to_disk``). See `Events`_ for + information on events. + +``state`` + (optional) the engine must be in this state number in order for this + rule to match. See `State transitions`_ for information + on states. + +``errno`` + the numeric errno value to return when a request matches this rule. + The errno values depend on the host since the numeric values are not + standardized in the POSIX specification. + +``sector`` + (optional) a sector number that the request must overlap in order to + match this rule + +``once`` + (optional, default ``off``) only execute this action on the first + matching request + +``immediately`` + (optional, default ``off``) return a NULL ``BlockAIOCB`` + pointer and fail without an errno instead. This + exercises the code path where ``BlockAIOCB`` fails and the + caller's ``BlockCompletionFunc`` is not invoked. + +Events +------ +Block drivers provide information about the type of I/O request they are a= bout +to make so rules can match specific types of requests. For example, the `= `qcow2`` +block driver tells ``blkdebug`` when it accesses the L1 table so rules can= match +only L1 table accesses and not other metadata or guest data requests. + +The core events are: + +``read_aio`` + guest data read + +``write_aio`` + guest data write + +``flush_to_os`` + write out unwritten block driver state (e.g. cached metadata) + +``flush_to_disk`` + flush the host block device's disk cache + +See ``qapi/block-core.json:BlkdebugEvent`` for the full list of events. +You may need to grep block driver source code to understand the +meaning of specific events. + +State transitions +----------------- +There are cases where more power is needed to match a particular I/O reque= st in +a longer sequence of requests. For example:: + + write_aio + flush_to_disk + write_aio + +How do we match the 2nd ``write_aio`` but not the first? This is where st= ate +transitions come in. + +The error injection engine has an integer called the "state" that always s= tarts +initialized to 1. The state integer is internal to ``blkdebug`` and canno= t be +observed from outside but rules can interact with it for powerful matching +behavior. + +Rules can be conditional on the current state and they can transition to a= new +state. + +When a rule's "state" attribute is non-zero then the current state must eq= ual +the attribute in order for the rule to match. + +For example, to match the 2nd write_aio:: + + [set-state] + event =3D "write_aio" + state =3D "1" + new_state =3D "2" + + [inject-error] + event =3D "write_aio" + state =3D "2" + errno =3D "5" + +The first ``write_aio`` request matches the ``set-state`` rule and transit= ions from +state 1 to state 2. Once state 2 has been entered, the ``set-state`` rule= no +longer matches since it requires state 1. But the ``inject-error`` rule n= ow +matches the next ``write_aio`` request and injects ``EIO`` (5). + +State transition rules support the following attributes: + +``event`` + which type of operation to match (e.g. ``read_aio``, ``write_aio``, + ``flush_to_os`, ``flush_to_disk``). See `Events`_ for + information on events. + +``state`` + (optional) the engine must be in this state number in order for this + rule to match + +``new_state`` + transition to this state number + +Suspend and resume +------------------ +Exercising code paths in block drivers may require specific ordering among= st +concurrent requests. The "breakpoint" feature allows requests to be halte= d on +a ``blkdebug`` event and resumed later. This makes it possible to achieve +deterministic ordering when multiple requests are in flight. + +Breakpoints on ``blkdebug`` events are associated with a user-defined ``ta= g`` string. +This tag serves as an identifier by which the request can be resumed at a = later +point. + +See the ``qemu-io(1)`` ``break``, ``resume``, ``remove_break``, and ``wait= _break`` +commands for details. diff --git a/docs/devel/testing/index.rst b/docs/devel/testing/index.rst index 45eb4a71814..9e772c7fd1d 100644 --- a/docs/devel/testing/index.rst +++ b/docs/devel/testing/index.rst @@ -14,3 +14,4 @@ testing infrastructure. acpi-bits ci fuzzing + blkdebug --=20 2.34.1