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Sun, 24 Feb 2019 12:54:01 +0200 Subject: Re: [PATCH] nvmet: disable direct I/O when unavailable To: Johannes Thumshirn , Chaitanya Kulkarni , Christoph Hellwig CC: Linux Kernel Mailinglist , "Linux NVMe Mailinglist" References: <20190221182234.22345-1-jthumshirn@suse.de> <6c3fa30a-d516-a453-a001-1014202ff9ce@suse.de> From: Max Gurtovoy Message-ID: <9d8e96de-d68d-8961-21e8-4cb8e79b4a08@mellanox.com> Date: Sun, 24 Feb 2019 12:54:01 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <6c3fa30a-d516-a453-a001-1014202ff9ce@suse.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.223.3.162] X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:193.47.165.134;IPV:NLI;CTRY:IL;EFV:NLI;SFV:NSPM;SFS:(10009020)(979002)(376002)(396003)(39850400004)(346002)(136003)(2980300002)(199004)(189003)(81166006)(8676002)(81156014)(6116002)(7736002)(305945005)(58126008)(356004)(110136005)(54906003)(230700001)(2906002)(316002)(16576012)(106002)(67846002)(23676004)(2486003)(50466002)(3846002)(47776003)(76176011)(65956001)(65826007)(229853002)(53546011)(77096007)(26005)(65806001)(186003)(8936002)(64126003)(16526019)(36756003)(86362001)(486006)(336012)(446003)(126002)(11346002)(2616005)(476003)(106466001)(6246003)(966005)(478600001)(31686004)(6306002)(4326008)(5660300002)(31696002)(3940600001)(969003)(989001)(999001)(1009001)(1019001);DIR:OUT;SFP:1101;SCL:1;SRVR:DBBPR05MB6585;H:mtlcas13.mtl.com;FPR:;SPF:Pass;LANG:en;PTR:mail13.mellanox.com;A:1;MX:1; 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Do we really want to support these kind of filesystems for fabrics backend device ? only for testing ? What is the status of iSCSI/SRP targets in this case ? > >> OR >> >> Similar result can be achieved by setting buffered I/O flag >> buffered_io=1 before enabling the name-space in the test script. > Frankly, we have a ton of testing related special cases in the kernel. > > This one is a) simple and small, only 10 LoC, b) far away from the fast > path or any other place where it could have any impact on legitimate > users and c) it prints an informal message showing you what happened. > > Sorry but this is a https://xkcd.com/386/ moment. > > Byte, > Johannes