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Tue, 29 Sep 2026 15:35:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id gN/3BKrau2oKKAAAD6G6ig (envelope-from ); Tue, 29 Sep 2026 15:35:06 +0000 From: Gabriel Krisman Bertazi To: Amir Goldstein Cc: linux-fsdevel@vger.kernel.org, Christian Brauner , Jan Kara , Theodore Ts'o , Hugh Dickins , Daniel Tang , linux-ext4@vger.kernel.org, Miklos Szeredi , linux-unionfs@vger.kernel.org, linux-mm@kvack.org, Chuck Lever , Pali =?utf-8?Q?Roh=C3=A1r?= Subject: Re: [PATCH 4/4] ovl: Expose the filesystem encoding through sysfs In-Reply-To: Organization: SUSE References: <20260928213155.2612039-1-krisman@suse.de> <20260928213155.2612039-5-krisman@suse.de> Date: Tue, 29 Sep 2026 11:35:04 -0400 Message-ID: <87mrt0xe8n.fsf@mailhost.krisman.be> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: pz54e4jzfxyguydxo8136p8rurzcsq5y X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5B9A28000B X-HE-Tag: 1790696116-644836 X-HE-Meta: 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 rbNOErNX kVeiIHPWEIUyg9i3DQVy53FvUHcMjvNK271NySO4TQFK0muafuw6m+fFJoMcdgWRLpbw8nCpqDWmiRI1cFKGQ3VMNHV+zVNuWPffaFOx4SJDQapJL9qq4PV6RjUu0r6icfDYHXFHZvzTpByjwPHVXR5oFUsaL9IInlMRKdPWphFqbuFLrdn6Sz/ob4sG/y9WL5e+6guNsIR9m1l30Lpm6D4OPKaqAHClPv/kUcexxYKpQ2rDNyo9jygtODbAMdvU6a4N1Vj8gMmlM1674sqsOFdbo5DDNiY5B7q5Y/EH4p6PZJ97YilnOzg12qD5RXUeiqKp6DQ3ZLZdTlYyqqWonC75YNJswHFDh3Hjdt7JHKXqHKVtSn0HhikAbNb6b8TwQ8jbZFTPDMd78tgjsg/OVJVRnp0JPj/Uc09vZLZBzJu2g5fDZwLbp1hcRu/G3bOKxG6wj Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Amir Goldstein writes: > On Mon, Sep 28, 2026 at 11:32=E2=80=AFPM Gabriel Krisman Bertazi > wrote: > I am not ok with this API. > It is wrong in several ways. > It is not generic, we have already file_getattr() to get casefold status. > There was a suggestion by Pali [1] to get the supported xflags - statx st= yle, > which can be a way to say if a fs could return FS_XFLAG_CASEFOLD. > In Chuck's v2 [2] FILEATTR_CASEFOLD_TYPE was already suggested > as an extension to file_getattr(). I think we can still do that if we inc= lude > proper versioning in the casefold type. Ok. I'm not fond of the overlay part of this series at all, in particular due to the major:minor design. I was looking for an alternative way to do it and didn't find it, thus /sys/fs. > TBH, I don't think anyone requested this - you only mentioned > the need to know if tmpfs was mounted with casefold on and that > doesn't mean that etx4/ovl patches are justified, but ext4 can decide > for themselves. There is a need for a proper probing API when deciding to fallback to userspace casefolding workarounds, and that is not shmem specific at all. I'm sure the Wine folks that right now use ext4/overlayfs will also benefit from a smarter way to fetch the information. > The point is that this sysfs is not going to be the standard for all the > fs that can return the FS_XFLAG_CASEFOLD, so I see no reason > to add this sysfs interface to ovl. Ack. I'll drop patches 3 and 4 and wait on ext4 people to see if they want patch 2 to match f2fs. Will also keep an eye on FS_XFLAG_CASEFOLD. > Thanks, > Amir. > > [1] https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@ker= nel.org/ > [2] https://lore.kernel.org/linux-fsdevel/20251211152116.480799-2-cel@ker= nel.org/ --=20 Gabriel Krisman Bertazi