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Received: from viro by zeniv.linux.org.uk with local (Exim 4.98 #2 (Red Hat Linux)) id 1tB107-0000000EIYh-2CYw; Wed, 13 Nov 2024 00:12:51 +0000 Date: Wed, 13 Nov 2024 00:12:51 +0000 From: Al Viro To: Linus Torvalds Cc: Amir Goldstein , Josef Bacik , kernel-team@fb.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, brauner@kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH v7 05/18] fsnotify: introduce pre-content permission events Message-ID: <20241113001251.GF3387508@ZenIV> References: <141e2cc2dfac8b2f49c1c8d219dd7c20925b2cef.1731433903.git.josef@toxicpanda.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam10 X-Stat-Signature: d7wpqsffp5xr9gkdpc5jhn4j6crorjgm X-Rspamd-Queue-Id: 8A07740005 X-Rspam-User: X-HE-Tag: 1731456743-958997 X-HE-Meta: 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 MBOTsLmc 0/x2ZDbkUBJ1a3Cwf3x8zME4tljRHHrYT0EPz9rV04oMOBMjObkAMDC2Sl+OmU8bvhv+UDZH/B4xi89zeMbp+79RfqoCeYahP2A0JFbeSr4WxsqBci9eaWDtSUTFB114mpsBiQ9+OjpPXIhsCobgLM2pNzm00kM+pd7OkAdskWDAaRoWi69RT1kNr2E83PZWnSOcn37FKOsyk+raHNeiXdS3K1cm+z9LpHD5A/VwfjsDpIQVT5WuRBF3p15AviW6Th6JHreEhEeSYXQ6xcyQ4Gc50Jvv2aEiEXGusUeOdIp55ORJOfmBBjfdj9uo1Dnse4v0in8f+sUHwgye7dg9ly3UXoBVTvkmZkz4cEJZUKbfvvHM3qhhVeCVSj1JhbvyamO0amxjnx027EqG3TUkv/tgIoz7jf1LRDaQX9RYhhUNvO0RrwYRdnGvGb6s/uERTtl3FRGuFDZycBLfB4QtGtsSez7VpzRJU83qm 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 Tue, Nov 12, 2024 at 03:48:10PM -0800, Linus Torvalds wrote: > On Tue, 12 Nov 2024 at 15:06, Amir Goldstein wrote: > > > > I am fine not optimizing out the legacy FS_ACCESS_PERM event > > and just making sure not to add new bad code, if that is what you prefer > > and I also am fine with using two FMODE_ flags if that is prefered. > > So iirc we do have a handful of FMODE flags left. Not many, but I do > think a new one would be fine. 8, 13, 24, 30 and 31. > But if anybody is really worried about running out of f_mode bits, we > could almost certainly turn the existing > > unsigned int f_flags; > > into a bitfield, and make it be something like > > unsigned int f_flags:26, f_special:6; > > instead, with the rule being that "f_special" only gets set at open > time and never any other time (to avoid any data races with fcntl() > touching the other 24 bits in the word). Ugh... Actually, I would rather mask that on fcntl side (and possibly moved FMODE_RANDOM/FMODE_NOREUSE over there as well). Would make for simpler rules for locking - ->f_mode would be never changed past open, ->f_flags would have all changes under ->f_lock.