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b=fld1ypw9APN84jvJm1OOVi3+ZHhpiCqzC8QK3ifg0qLQZgEH8RQwQdH9O+qgnCYrc Sl4P80xhdmTewu6/ueUPwz49MOXYxB6UBItK5OTQ0jNrXM+RhuWFzcbq8/AWs+iJAF sWwz/T9UUHbDSE6lBJmFzuV/C0rrwCCV/lVPg4G1C8T1NTPTVkDkijsvMe8RDW8nZA LZLL7Urvwe4SUWrAFQbjev8VcLMOGCOX2SkHENYXY+5glXf5Ca4NrlNsci9Of0Z5lp wuu95IWJCelZn/vv77Jo3iZBmgg6TAwqcTk9PAgwVxz35w1q73aBen2fJCrKohTcUa sPyncu6PC/Yqw== Date: Thu, 21 May 2026 22:53:31 -0500 From: Eric Biggers To: Jaegeuk Kim Cc: Theodore Tso , Christoph Hellwig , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox , linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Akilesh Kailash , Christian Brauner Subject: Re: [f2fs-dev] [PATCH v2] f2fs: another way to set large folio by remembering inode number Message-ID: <20260522035331.GE5937@quark> References: <20260409134538.3692605-1-jaegeuk@kernel.org> <20260521155748.GA79343@macsyma-wired.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 5aewp5tsa648orzmu33xtzp6tcm5z8xt X-Rspamd-Queue-Id: 2C9B62000E X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1779422015-602814 X-HE-Meta: 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 4gtqX2jP RMJDpynutKvzJ0pYjCN/IMnLYjZqD+rgiRceqzf/dluSmYJeu5Yb+o25LBYFh3EpAb0hObCBHW0EG5Z1kOqm/NJ0ZT15Z3EejKodkR+UedkvqiENJrELlH7cGg8ILOYVCUhHix8t3sFFtMUiBCxizCbPS577dCiUZdh0WdzA00claUxHDPUES073CcUI0K46sSLUe3jmx1RMgganZo1M7R4kIAxOTkO2KlcUIvtuOGZcfWEh5S63Vu/g/H1N0TPFPaov1 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 22, 2026 at 03:32:39AM +0000, Jaegeuk Kim wrote: > On 05/21, Theodore Tso wrote: > > On Thu, May 21, 2026 at 01:51:08AM -0700, Christoph Hellwig wrote: > > > > You haven't sent a proposal. This is a reply to a reply to a reply of a > > > > patch. There's no justification for why f2fs is so special that it > > > > needs this. What the hell is going on? You know this is not the way to > > > > get code merged into Linux. > > > > > > None of this got properly answers, and this broken interface now landed > > > in linux-next. IT is offloading a user.* xattr which is free-form > > > user data with semantics that are weird to say it very nicely. > > > > > > All this was done against the advice in the mailing list discussion. > > > > So let me get this straight. This is a magic xattr interface which is > > not even persisted in the file system, but instead sets a 32-bit > > bitmask in the struct inode which disappears once the inode gets > > flushed from the inode stack. And it uses a generic xattr name, > > "user.fadvise". > > > > There's no way in *hell* any other file system is likely to adopt such > > a broken interface, so why didn't you just use an ioctl to set this > > magic f2fs-specific flag? > > I went this route because Android heavily restricts ioctl() permissions > and we needed broader access for this to work within the framework. It's straightforward (2 lines I think) to update Android's SELinux policy to allow an ioctl in all domains. So that doesn't seem like a reason to not use an ioctl. In fact this is actually a reason *to* use an ioctl, as it shows that ioctls can be allowed/denied independently as needed, whereas xattrs just use the file write permission. - Eric