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Ts'o" To: CC: , Subject: [LSF/MM TOPIC] Standardizing semantics around the per-file DAX flag Message-ID: <20190213164039.GA16285@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:18.9.28.11;IPV:CAL;SCL:-1;CTRY:US;EFV:NLI;SFV:NSPM;SFS:(10019020)(396003)(346002)(376002)(136003)(39860400002)(2980300002)(189003)(199004)(36756003)(246002)(356004)(478600001)(6266002)(26826003)(103686004)(4744005)(305945005)(90966002)(86362001)(4326008)(8676002)(8936002)(46406003)(316002)(42186006)(786003)(88552002)(186003)(106466001)(75432002)(33656002)(476003)(23726003)(126002)(2351001)(58126008)(2906002)(52956003)(486006)(336012)(36906005)(1076003)(47776003)(6916009)(26005)(54906003)(106002)(2616005)(97756001)(16586007)(50466002)(18370500001)(42866002);DIR:OUT;SFP:1102;SCL:1;SRVR:SN6PR01MB4989;H:outgoing.mit.edu;FPR:;SPF:Pass;LANG:en;PTR:outgoing-auth-1.mit.edu;MX:1;A:1; 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(Or maybe only if the file is otherwise opened anywhere in the system?) * Should it only takes effect when the file system is unmounted, or when the inode drops out of the inode cache? * Should we remove the flag entirely and make it be something the system automagically infers? I had hoped consensus would be achieved before the ext4 per-file DAX flag lands, but it hasn't for a *long* time. Technically the DAX flag is "experimental", which technically means it could be removed --- although I suspect at this point, it would break some userspace, so our options about how to adjust the semantics of the flag are probably constrained. - Ted