From nobody Thu Sep 24 20:37:31 2026 Received: from zg8tmtyylji0my4xnjqumte4.icoremail.net (zg8tmtyylji0my4xnjqumte4.icoremail.net [162.243.164.118]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 85838386C39 for ; Sun, 20 Sep 2026 08:31:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.243.164.118 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893098; cv=none; b=j6443ie5Nw7aki2G/HuXzhkVfkg34EI8kgP3CIY7TD+HJ/i0f1e3TpP+ISDM+nCMAb4MplwoK3zQdihOAX162i6RknhBoJy+hLrUI6HiQThOIe5T1TypRAX5NZHjXbqDBVCCVxaAvidBrWy6+plrw7C2XFYHM0tODPRhxBFh5V4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893098; c=relaxed/simple; bh=CHhlOoPa7lx28znIBmmKknG7qrENE5LL/JiYPgofib8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qXwQUwZe1zgW+FMDjgVd3A1wZ0DCJDSuZymzI+lJqR/2vETE95PGuDBDR/zOFxhaUCui5r9XVx9L/DvJTedC5bOOn/NAZS1UrJ9k7eD61N2ZP6UpwbpV3+YY8GyEVuRcUdPuvlDJfOE67n0XsvGJbRHCb/LQXGtx6slUx03F1gc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=162.243.164.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [117.147.104.32]) by mtasvr (Coremail) with SMTP id _____wAn0zzgma9quNImAQ--.24630S3; Sun, 20 Sep 2026 16:31:28 +0800 (CST) Received: from localhost.localdomain (unknown [117.147.104.32]) by mail-app3 (Coremail) with SMTP id zS_KCgAHQXTSma9qV+dHBQ--.54809S3; Sun, 20 Sep 2026 16:31:27 +0800 (CST) From: Jiacheng Xu To: Andreas Gruenbacher Cc: Jiacheng Xu , gfs2@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/4] gfs2: protect quota refresh from superblock teardown Date: Sun, 20 Sep 2026 16:31:02 +0800 Message-ID: <20260920083109.30798-2-stitch@zju.edu.cn> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260920083109.30798-1-stitch@zju.edu.cn> References: <20260920083109.30798-1-stitch@zju.edu.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zS_KCgAHQXTSma9qV+dHBQ--.54809S3 X-CM-SenderInfo: qtrxiiaqttimo62m3hxhgxhubq/ X-CM-DELIVERINFO: =?B?ZqNvyQXKKxbFmtjJiESix3B1w3tMoM3snk/k5SVzZVydjEqe1eefKHnLf95EnB4iem egWzO/wNhIP+pglnkLd0BnOseRu3vBlUcX6QlLMsS925UAZSEknj3LGDy6z/wpMoOg8cy1 tPbWVAvh7xu1Ium4Jp1zGNLdsMyhd8Xna2fzX/b1 X-Coremail-Antispam: 1Uk129KBj93XoWxZFykJFWUAw1xXrW3Kr13Jrc_yoW5Wr47pF 4jv3yfJr4kCrnrXF4SkF4rW34rG393ZFy7trZ7W3Z3Aw42ywnxKFyfJFy0vFyrG348Jrnr XF1jvFZxCrWUGrcCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUvmb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AK xVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAF wI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0Y48IcxkI7V AKI48G6xCjnVAKz4kxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I 3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxV WUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8I cVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZE Xa7IU88hL5UUUUU== Content-Type: text/plain; charset="utf-8" The quota_refresh sysfs attributes become visible before fill_super() has completed, so the quota inode can still be uninitialized when a userspace write reaches gfs2_quota_refresh(). The same callback can also race with superblock teardown. Serialize the callback with the superblock lifetime using a read-side s_umount lock. Use down_read_trylock() so the mount failure path can remove the sysfs files while holding the write side of the lock without deadlocking, and reject accesses before SB_ACTIVE is set. Keep the locking in the user and group sysfs callbacks and introduce shared helpers for the other sysfs operations. Return -EAGAIN when the filesystem is not available for the callback. Signed-off-by: Jiacheng Xu --- fs/gfs2/sys.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index ea2c7b9e4a77..0d247299625c 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -63,6 +63,25 @@ static ssize_t id_show(struct gfs2_sbd *sdp, char *buf) MAJOR(sdp->sd_vfs->s_dev), MINOR(sdp->sd_vfs->s_dev)); } =20 +/* + * Sysfs callbacks must not block on s_umount: mount failure and unmount + * remove the sysfs files while holding it for writing. + */ +static bool super_trylock_shared_active(struct super_block *sb) +{ + if (!down_read_trylock(&sb->s_umount)) + return false; + if (sb->s_flags & SB_ACTIVE) + return true; + up_read(&sb->s_umount); + return false; +} + +static void super_unlock_active(struct super_block *sb) +{ + up_read(&sb->s_umount); +} + static ssize_t status_show(struct gfs2_sbd *sdp, char *buf) { unsigned long f =3D sdp->sd_flags; @@ -248,6 +267,7 @@ static ssize_t quota_sync_store(struct gfs2_sbd *sdp, c= onst char *buf, static ssize_t quota_refresh_user_store(struct gfs2_sbd *sdp, const char *= buf, size_t len) { + struct super_block *sb =3D sdp->sd_vfs; struct kqid qid; int error; u32 id; @@ -263,13 +283,19 @@ static ssize_t quota_refresh_user_store(struct gfs2_s= bd *sdp, const char *buf, if (!qid_valid(qid)) return -EINVAL; =20 + if (!super_trylock_shared_active(sb)) + return -EAGAIN; + error =3D gfs2_quota_refresh(sdp, qid); + + super_unlock_active(sb); return error ? error : len; } =20 static ssize_t quota_refresh_group_store(struct gfs2_sbd *sdp, const char = *buf, size_t len) { + struct super_block *sb =3D sdp->sd_vfs; struct kqid qid; int error; u32 id; @@ -285,7 +311,12 @@ static ssize_t quota_refresh_group_store(struct gfs2_s= bd *sdp, const char *buf, if (!qid_valid(qid)) return -EINVAL; =20 + if (!super_trylock_shared_active(sb)) + return -EAGAIN; + error =3D gfs2_quota_refresh(sdp, qid); + + super_unlock_active(sb); return error ? error : len; } =20 --=20 2.51.0 From nobody Thu Sep 24 20:37:31 2026 Received: from zg8tndyumtaxlji0oc4xnzya.icoremail.net (zg8tndyumtaxlji0oc4xnzya.icoremail.net [46.101.248.176]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D5D6D3E9589 for ; Sun, 20 Sep 2026 08:31:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.101.248.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893101; cv=none; b=otQDs1X+CwiIetBfra4sjvKSfvgs81lzFCO9UNX3EeuyC15oZVa8fROjhfb4XvnWseA/nbLKYiLzqPpCmf8d+5j1ZKK6pdFfmk3XHapS2H0l07MgnmQOobctpbAEqbapio1eqKomsJm9pY58VsNRGv2MRliddgPR227Q/EtMAfQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893101; c=relaxed/simple; bh=0mavBG8jADwhQv6KhYL+X91lG6MhE7mLPcuhg51y/rk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bfHIUo49moFpCaAJCqsMbWCZQ3bLPYkdnAuCK4/GdiknZea+yo8WZ4bg+HnS5TsDuLUQk9jDKhZ76jnFxCvTFQfd0hC76FRk6Jnm6zqjlZLlIYmupPmgDZljiWD0hh+SHw9z+2kvkCDGQJDK6diQoBxLvE7Y2vL/XkaHjxyFPqg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=46.101.248.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [117.147.104.32]) by mtasvr (Coremail) with SMTP id _____wCHgD_ima9qvdImAQ--.25120S3; Sun, 20 Sep 2026 16:31:30 +0800 (CST) Received: from localhost.localdomain (unknown [117.147.104.32]) by mail-app3 (Coremail) with SMTP id zS_KCgAHQXTSma9qV+dHBQ--.54809S4; Sun, 20 Sep 2026 16:31:29 +0800 (CST) From: Jiacheng Xu To: Andreas Gruenbacher Cc: Jiacheng Xu , gfs2@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/4] gfs2: protect statfs sync sysfs callback Date: Sun, 20 Sep 2026 16:31:03 +0800 Message-ID: <20260920083109.30798-3-stitch@zju.edu.cn> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260920083109.30798-1-stitch@zju.edu.cn> References: <20260920083109.30798-1-stitch@zju.edu.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zS_KCgAHQXTSma9qV+dHBQ--.54809S4 X-CM-SenderInfo: qtrxiiaqttimo62m3hxhgxhubq/ X-CM-DELIVERINFO: =?B?ZJr9bgXKKxbFmtjJiESix3B1w3tMoM3snk/k5SVzZVydjEqe1eefKHnLf95EnB4iem egWzO/wNhIP+pglnkLd0BnOscvQVO6NqLDoKOrWoE6q5PZHv56cT8BWJRDUtThYGkWp+Pf LkD8QZ23s48MrbYdbPISji9OAfmK+DAn36hRITZ1 X-Coremail-Antispam: 1Uk129KBj93XoW7tw45Xw1xKry8XF1rKw13KFX_yoW8Gr13pF nrZr15Gw1kGr18Xa4vkF4Fg3W8CayrtFy3K34vqwnrZan8JwnIq34xKFyj9Fy8ArZrGry7 Wr4vvasIyFWUGrcCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUvmb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AK xVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAF wI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0Y48IcxkI7V AKI48G6xCjnVAKz4kxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I 3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxV WUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8I cVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZE Xa7IU8c4S7UUUUU== Content-Type: text/plain; charset="utf-8" The statfs_sync sysfs file remains accessible while gfs2_put_super() releases sd_statfs_inode during unmount. A concurrent write can then enter gfs2_statfs_sync() and dereference the released inode. Serialize the sysfs callback with the superblock lifetime. Use a non-blocking read lock so mount failure and unmount paths can remove the sysfs files while holding s_umount for writing, and reject access before the superblock becomes active. Signed-off-by: Jiacheng Xu --- fs/gfs2/sys.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index 0d247299625c..fd6e8e34651d 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -229,6 +229,7 @@ static ssize_t withdraw_store(struct gfs2_sbd *sdp, con= st char *buf, size_t len) static ssize_t statfs_sync_store(struct gfs2_sbd *sdp, const char *buf, size_t len) { + struct super_block *sb =3D sdp->sd_vfs; int error, val; =20 if (!capable(CAP_SYS_ADMIN)) @@ -241,7 +242,12 @@ static ssize_t statfs_sync_store(struct gfs2_sbd *sdp,= const char *buf, if (val !=3D 1) return -EINVAL; =20 - gfs2_statfs_sync(sdp->sd_vfs, 0); + if (!super_trylock_shared_active(sb)) + return -EAGAIN; + + gfs2_statfs_sync(sb, 0); + + super_unlock_active(sb); return len; } =20 --=20 2.51.0 From nobody Thu Sep 24 20:37:31 2026 Received: from azure-sdnproxy.icoremail.net (azure-sdnproxy.icoremail.net [13.76.78.106]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 620603EB108 for ; Sun, 20 Sep 2026 08:31:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.76.78.106 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893103; cv=none; b=RpwkUTAtZi646tHa/tMPxB6iYTM4I2phNyRXHA4DHGR9h78+l64bdZxJD9aMUlJUtZvEVYTIV8WTiXZlU7esDPlcex5whAEnvk4wjLo88JLE6vfgjsF/lUeY+Gv7mtlFTAyketrk4czhsovO7OqBx4OCS2G7ApKz4l9Ze3VCrpU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893103; c=relaxed/simple; bh=63zvDyDYTKhpsmfDe4JGT9VugeFbT7PqwwXNnTQkqJQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CT4pFfonPAILISOgc2PXgqkCHPleVkbAX98KsfdpEgn9UZ48RdRvxDFgANd5//zRk1HzM6f+mjyow0GwLomhIAelw1l9jXKX7IMC3a8SSZxru+hqyryRyZJRfKUVEEGJl1Qo3V8NvESs+VspwVbh+98kGFgRwurAxI5tbLinkVk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=13.76.78.106 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [117.147.104.32]) by mtasvr (Coremail) with SMTP id _____wC3oH7lma9qw9ImAQ--.24617S3; Sun, 20 Sep 2026 16:31:33 +0800 (CST) Received: from localhost.localdomain (unknown [117.147.104.32]) by mail-app3 (Coremail) with SMTP id zS_KCgAHQXTSma9qV+dHBQ--.54809S5; Sun, 20 Sep 2026 16:31:31 +0800 (CST) From: Jiacheng Xu To: Andreas Gruenbacher Cc: Jiacheng Xu , gfs2@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/4] gfs2: protect quota sync sysfs callback Date: Sun, 20 Sep 2026 16:31:04 +0800 Message-ID: <20260920083109.30798-4-stitch@zju.edu.cn> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260920083109.30798-1-stitch@zju.edu.cn> References: <20260920083109.30798-1-stitch@zju.edu.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zS_KCgAHQXTSma9qV+dHBQ--.54809S5 X-CM-SenderInfo: qtrxiiaqttimo62m3hxhgxhubq/ X-CM-DELIVERINFO: =?B?wcOPBAXKKxbFmtjJiESix3B1w3tMoM3snk/k5SVzZVydjEqe1eefKHnLf95EnB4iem egWzO/wNhIP+pglnkLd0BnOsedvbXcnNGX/UIepARfWBncHv56cT8BWJRDUtThYGkWp+Pf LkD8QZ23s48MrbYdbPJPcfx2W6bE1TLvArMXh2x0 X-Coremail-Antispam: 1Uk129KBj93XoW7Xw48tr4xtFyrAw4kWFyfAFc_yoW8Jr4UpF 4DAr13Cas8Jr1UWFWDKFsYgw1rGa92qFW7trZrX3ZrJ3ZxJwnxJFyxKa40vFyUXrW7Jr13 ur9YvasIyFW8GFcCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUvmb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AK xVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAF wI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0Y48IcxkI7V AKI48G6xCjnVAKz4kxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I 3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxV WUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8I cVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZE Xa7IU8c4S7UUUUU== Content-Type: text/plain; charset="utf-8" The quota_sync sysfs callback can run while quota cleanup is releasing the quota bitmap and internal quota inodes during mount rollback or unmount. Hold s_umount for reading while synchronizing quota data and reject requests before the superblock is active. Use trylock semantics so the callback cannot deadlock with the write-side teardown path. Signed-off-by: Jiacheng Xu --- fs/gfs2/sys.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index fd6e8e34651d..c5868354073a 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -254,6 +254,7 @@ static ssize_t statfs_sync_store(struct gfs2_sbd *sdp, = const char *buf, static ssize_t quota_sync_store(struct gfs2_sbd *sdp, const char *buf, size_t len) { + struct super_block *sb =3D sdp->sd_vfs; int error, val; =20 if (!capable(CAP_SYS_ADMIN)) @@ -266,7 +267,12 @@ static ssize_t quota_sync_store(struct gfs2_sbd *sdp, = const char *buf, if (val !=3D 1) return -EINVAL; =20 - gfs2_quota_sync(sdp->sd_vfs, 0); + if (!super_trylock_shared_active(sb)) + return -EAGAIN; + + gfs2_quota_sync(sb, 0); + + super_unlock_active(sb); return len; } =20 --=20 2.51.0 From nobody Thu Sep 24 20:37:31 2026 Received: from fraori-sdnproxy-3.icoremail.net (fraori-sdnproxy-3.icoremail.net [132.226.202.154]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C0D7B3E2AD7 for ; Sun, 20 Sep 2026 08:31:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=132.226.202.154 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893104; cv=none; b=NMZO77CZXm0FUEvQ5gmWa4e9SZLK5ri3UYdci6zDP6dMtdd2d57Qswz5C+p1/SCyU3eaZ4yWVeItYf74u7GIQaFzkg4Tveiutn6KSc0WXgVrqZCuv2THA+7eFM3lnvp2F/L64LENge78/Gj1bLgTFNQ47YcfvftXISfpX8iVBEs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789893104; c=relaxed/simple; bh=sJYcwxctMXiLIvjjZSZKMGlbOPXMpp1oWismY7OL1zM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fxIcSZCA0xYZluOEGhicV1uC2r+cfp1NNcRHCm9Pk4WpJrUjZuH1HOQ1TobAPZPvZei7sfyiP1PUJ6URYWGlNL8bEv0cd9jD5zOfMeDGfNI4sHd3iXfaLKkU6TPJFcUOCuC1LJHLBaNSXRo+xje+nnvyEnEwPhPMoqBhrbDbwdQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=132.226.202.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [117.147.104.32]) by mtasvr (Coremail) with SMTP id _____wCXkD_pma9qztImAQ--.24559S3; Sun, 20 Sep 2026 16:31:37 +0800 (CST) Received: from localhost.localdomain (unknown [117.147.104.32]) by mail-app3 (Coremail) with SMTP id zS_KCgAHQXTSma9qV+dHBQ--.54809S6; Sun, 20 Sep 2026 16:31:34 +0800 (CST) From: Jiacheng Xu To: Andreas Gruenbacher Cc: Jiacheng Xu , gfs2@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3 4/4] gfs2: protect demote requests during superblock teardown Date: Sun, 20 Sep 2026 16:31:05 +0800 Message-ID: <20260920083109.30798-5-stitch@zju.edu.cn> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260920083109.30798-1-stitch@zju.edu.cn> References: <20260920083109.30798-1-stitch@zju.edu.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zS_KCgAHQXTSma9qV+dHBQ--.54809S6 X-CM-SenderInfo: qtrxiiaqttimo62m3hxhgxhubq/ X-CM-DELIVERINFO: =?B?Gn/BywXKKxbFmtjJiESix3B1w3tMoM3snk/k5SVzZVydjEqe1eefKHnLf95EnB4iem egWzO/wNhIP+pglnkLd0BnOseKeJr8bipqX23HM2eq1rHBHv56cT8BWJRDUtThYGkWp+Pf LkD8QZ23s48MrbYdbPLtWmujtIG9rr2oMH3HiwlP X-Coremail-Antispam: 1Uk129KBj93XoW7uF1rWF4Dur1rGw4kCFWDZFc_yoW8WrW7pr 4UC345ZF4kCrn8Xa1Ikr4rWw1rKayfJF12y397WwsrJF15XwnIg34fKFW8tFyrA3yxXryq gFyYv39xCrWUGFcCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUvmb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AK xVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYIkI8VC2zVCFFI0UMc 02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUAVWUtwAv7VC2z280aVAF wI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0Y48IcxkI7V AKI48G6xCjnVAKz4kxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I 3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxV WUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8I cVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aV AFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZE Xa7IU8x9N3UUUUU== Content-Type: text/plain; charset="utf-8" The demote_rq sysfs callback can obtain a glock while unmount is tearing down the glock hash and destroying sd_glock_wq. The callback may then queue work through the destroyed workqueue. Serialize the complete demote operation with s_umount and reject requests while the superblock is not active. trylock semantics avoid deadlocking with mount failure and unmount paths that remove sysfs. Signed-off-by: Jiacheng Xu --- fs/gfs2/sys.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index c5868354073a..c5c540fcce92 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -334,6 +334,7 @@ static ssize_t quota_refresh_group_store(struct gfs2_sb= d *sdp, const char *buf, =20 static ssize_t demote_rq_store(struct gfs2_sbd *sdp, const char *buf, size= _t len) { + struct super_block *sb =3D sdp->sd_vfs; struct gfs2_glock *gl; const struct gfs2_glock_operations *glops; unsigned int glmode; @@ -367,14 +368,22 @@ static ssize_t demote_rq_store(struct gfs2_sbd *sdp, = const char *buf, size_t len glops =3D gfs2_glops_list[gltype]; if (glops =3D=3D NULL) return -EINVAL; + + if (!super_trylock_shared_active(sb)) + return -EAGAIN; + if (!test_and_set_bit(SDF_DEMOTE, &sdp->sd_flags)) fs_info(sdp, "demote interface used\n"); rv =3D gfs2_glock_get(sdp, glnum, glops, NO_CREATE, &gl); if (rv) - return rv; + goto out_unlock; gfs2_glock_cb(gl, glmode); gfs2_glock_put(gl); - return len; + rv =3D 0; + +out_unlock: + super_unlock_active(sb); + return rv ? rv : len; } =20 =20 --=20 2.51.0