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[178.84.201.199]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c46bd34f465sm721068766b.8.2026.10.29.04.53.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Oct 2026 04:53:10 -0700 (PDT) Date: Thu, 29 Oct 2026 12:53:09 +0100 From: Amir Goldstein To: Pedro Falcato Cc: koraynilay , David Sterba , Alexander Viro , Christian Brauner , Chris Mason , Jan Kara , "Darrick J . Wong" , Sean Smith , Andrey Albershteyn , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 1/2] vfs: add provenance time (ptime) Message-ID: References: <20261028134728.294127-1-koray.fra@gmail.com> <20261028134728.294127-2-koray.fra@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Oct 28, 2026 at 02:56:39PM +0000, Pedro Falcato wrote: > On Wed, Oct 28, 2026 at 02:47:27PM +0100, koraynilay wrote: > > Add provenance time (ptime), indicating the time when a file or > > directory was created. This is user-settable via file_setattr() and > > retrievable via statx(2) (using STATX_PTIME) or file_getattr(). > > > > The semantics of when to preserve this new timestamp are the same as > > mtime, the idea being that there is a correspondence like this: > > > > ctime <-> btime > > mtime <-> ptime > > > > so every operation (copying, moving, ...) that currently preserves mtime > > should also preserve ptime. > > > > Furthermore, in order to avoid the legacy FS_IOC_FSSETXATTR accepting > > FS_XFLAG_PTIME, add an FS_FILE_ATTR_XFLAGS_MASK mask to support new > > xflags, and use it in fileattr_to_file_attr()/file_attr_to_fileattr() to > > allow ptime to be used with the file_setattr()/file_getattr() syscalls. > > Random comment, but: could this be doable with xattrs instead? I'm not sure > where I would put the xattrs code (if in userspace exclusively, or if hooking > the VFS up with this, or if doing it on the filesystem side), but it would > surely be less disruptive than modifying a bunch of filesystems one-by-one. > > This patch is quite simple, but changing btrfs, then ext4, xfs, etc is a > mess, and inevitably you can't get these timestamps until you upgrade your > filesystems. > I disagree. I think that creation time should be a first class property in filesystems that support it. Thanks, Amir.