From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2F1FC3E44ED for ; Fri, 18 Sep 2026 08:43:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789721010; cv=none; b=PU2dfG+N95xGI/vVLCh4EDdvJl1bVee8wpuwmHyStCw+zBTGoi90DD2Z1o9OA9JikSplry4/8emItA3nVgmBM64eMZIFKsy4a0u5i08K9YWjDlr1FBmCSCvc9M/9usFvyKMSk0ue+GKzKkXjS4j80xRQt84hdCXbbXiTBtkSlQk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789721010; c=relaxed/simple; bh=B8enl7XajpNalonsPTNgKNafhkdgqqD/Md62FHaEKmQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=r44H/mqNmYPQDmv55ENgr2vR7j2ByaW+WxJwJzFFuguftMs9SsLP9jCmW0OVTkxhBHYc7n4FzAunz7jmA5VdLpxbI0kmmnpc0ojs37RTMhGHTDFPW3jY4GwmNdQnet2pQ/3TGgu3vI7EQ0OkBvj7vSc1XaSG1UF0fi2yU+Nly7M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ScZxygwk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ScZxygwk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82B6A1F000FF; Fri, 18 Sep 2026 08:43:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789721006; bh=5j1ZVmoODEcnt056LhDW9rRHbMWXo37OrUcqNILKcwU=; h=From:To:Cc:Subject:Date; b=ScZxygwka8S4W21pTvCB0VD1eAZ77lzxKrkb//YhDSqv0vOEMQv3K6Rm3tT34v5XZ WiilUdeWeUYgyLuiW8u5cMdgF4hQI8xBY2gFB2ujAjqc/tIiYOdyI13XLsQIgmCeP3 37JQpL43B/MbIl+BSHXLZ8T+8Q2dF58Ht2npyLfx0LWWjX9Gbi2vo2TVZkRssmFdbC PamHb3RAOvezhUBqFN90PPyZHaKz0F40Opy3Cu9pnAqIJtQwxmx1lc4HtPdXtAqPFd g7s7EDT/mL+vLzGs7jKkM2cxneILqj7/bhGPZu8TC0QLcADJCMj1ezVsTa8sWxHgVS rogmOOuz4ZTVw== From: Anand Jain To: linux-btrfs@vger.kernel.org, dsterba@suse.cz Cc: Your Name Subject: [PATCH] btrfs-progs: docs: document the temp_fsid feature in btrfs(5) Date: Fri, 18 Sep 2026 16:42:43 +0800 Message-ID: X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Your Name The temp_fsid feature (kernel 6.7) is missing from the FILESYSTEM FEATURES list in btrfs(5). It's exposed in sysfs (/sys/fs/btrfs/features/temp_fsid and /sys/fs/btrfs//temp_fsid) like any other feature, but has no corresponding entry in the manual page. Add an entry describing what it does, when it applies (single-device filesystems only) and its exclusivity with metadata_uuid, following the existing entry format and alphabetical ordering. Signed-off-by: Anand Jain --- Documentation/btrfs-man5.rst | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/btrfs-man5.rst b/Documentation/btrfs-man5.rst index ce4021ab84b5..2635f06a1394 100644 --- a/Documentation/btrfs-man5.rst +++ b/Documentation/btrfs-man5.rst @@ -199,6 +199,22 @@ supported_rescue_options list of values for the mount option *rescue* that are supported by the running kernel, see :doc:`btrfs-man5` +temp_fsid + (since: 6.7) + + indicates the filesystem is mounted using a randomly generated, in-memory only + substitute for the on-disk filesystem UUID, needed because another filesystem + exposing the same UUID (e.g. a block-level clone) is already mounted. The + on-disk UUID, as reported by :command:`blkid`, is unchanged; the statfs + filesystem ID *f_fsid* returned by :manref:`statfs(2)` for this mount reflects + the substitute, and is regenerated on every such mount. + + Supported only for single-device filesystems, mutually exclusive with + *metadata_uuid*, and disables :command:`device add` for the mount. To make a + clone permanently independent instead of relying on temp_fsid on every mount, + change its on-disk UUID with :doc:`btrfstune` (*-u* or *-U*) while unmounted. + See also section :ref:`SYSFS INTERFACE`. + vefity (since: 5.15, CONFIG_FS_VERITY) -- 2.43.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC11D48595F for ; Fri, 18 Sep 2026 08:46:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789721180; cv=none; b=WM+0mkn6Pgykq19PPplOgfwM0B8Q5QGBehrjr6g5RnEmXxUynT3kezkWi4yGVYzOYCkabojG27lrVU22b0dTKjIA1UolCphIVvaI8svurHuOk0AUz08uQIeKQU21Ec9j3OcQSHTTRIKF4UHNYsy8BqGbJe/SmN5ZGJ7W/uxADSc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789721180; c=relaxed/simple; bh=SnilOYhHPWLorvYiSKn18mmkmOJS7rbS2CLd8duTDyk=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=qCUarARM2BdkKEBFM2sNUoaI5ch2/J0K+FrloXtILSBTyPT6cYfnBxsrKP/jci6mcHB52oAnmCLVBk28rQnTCTUrLDJH/8fa19yly3DhVeixQb/X9DzfwpuXGWaFjNWb3MRHT1+vCePrgVwCG/WgWBFZ5pp/Czkuw0fTH8J4ALo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mN3FPhM2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mN3FPhM2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7B201F0089A; Fri, 18 Sep 2026 08:46:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789721178; bh=MbESS7J92GOVmxFo8OSOvdF59v7n2rIrOBipNWC3NYo=; h=From:To:Subject:Date; b=mN3FPhM2uVSIlIqm6dUTzrANn/6CUXZK210HO00IAdE9PrRZ59Zzy+e0Xh4Udw9dY sTxjhX83P+5rnrSclOtVtndl8Q0dhPeZiUl2qxaLJTsHq1FZs8rVOUSeGcs1qqNA9L uA4rT/VYXpOUPUv/QRhlej98c//PcFfLgYYssvOeJMR7GawKfKpQDLe86/CiK7hx4G Pz7asbBdBGZjpTiB4toqYTOuK+DfaEAEox8h3vzezG4BTDZJupGbk89/338plvN/t/ U79ZUNhCv423dEivvKAFsPMoWTfDf0Erfa1u1HzoVXU39M/uU0qADIKtTfduo3F/lv wnRY0lKimAb8A== From: Anand Jain To: linux-btrfs@vger.kernel.org, dsterba@suse.cz Subject: [PATCH] btrfs-progs: docs: document the temp_fsid feature in btrfs(5) Date: Fri, 18 Sep 2026 16:46:12 +0800 Message-ID: X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID: <20260918084612.ZxGVtNO9DAJfevT0EwV5BlMy-4qgIyRKK6TAZ5oNLtU@z> The temp_fsid feature (kernel 6.7) is missing from the FILESYSTEM FEATURES list in btrfs(5). It's exposed in sysfs (/sys/fs/btrfs/features/temp_fsid and /sys/fs/btrfs//temp_fsid) like any other feature, but has no corresponding entry in the manual page. Add an entry describing what it does, when it applies (single-device filesystems only) and its exclusivity with metadata_uuid, following the existing entry format and alphabetical ordering. Signed-off-by: Anand Jain --- Documentation/btrfs-man5.rst | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/btrfs-man5.rst b/Documentation/btrfs-man5.rst index ce4021ab84b5..2635f06a1394 100644 --- a/Documentation/btrfs-man5.rst +++ b/Documentation/btrfs-man5.rst @@ -199,6 +199,22 @@ supported_rescue_options list of values for the mount option *rescue* that are supported by the running kernel, see :doc:`btrfs-man5` +temp_fsid + (since: 6.7) + + indicates the filesystem is mounted using a randomly generated, in-memory only + substitute for the on-disk filesystem UUID, needed because another filesystem + exposing the same UUID (e.g. a block-level clone) is already mounted. The + on-disk UUID, as reported by :command:`blkid`, is unchanged; the statfs + filesystem ID *f_fsid* returned by :manref:`statfs(2)` for this mount reflects + the substitute, and is regenerated on every such mount. + + Supported only for single-device filesystems, mutually exclusive with + *metadata_uuid*, and disables :command:`device add` for the mount. To make a + clone permanently independent instead of relying on temp_fsid on every mount, + change its on-disk UUID with :doc:`btrfstune` (*-u* or *-U*) while unmounted. + See also section :ref:`SYSFS INTERFACE`. + vefity (since: 5.15, CONFIG_FS_VERITY) -- 2.43.0