From patchwork Wed Nov 6 11:50:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 13864545 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7368D1F667B for ; Wed, 6 Nov 2024 11:50:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730893851; cv=none; b=NON4Y9dQPQvz0X9eMqSL1H1rfy0ykUNerDEZaULx8rumC61i2kHx9zJIXfpewaInIGgG+HwxizofUleLzo+Td66vegnATK24Yw4rQR8lTU5wDMV5Lssk2CugzQQh+6HDXCpKgOGnlHzZQQDfS1XtSrVDeJPAJ1aDVXCLqB/UKkg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730893851; c=relaxed/simple; bh=zKzX8IxewO2WjA9xl9/q2XAm335FISAh0Ki8XKJI/is=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GXbGaUqB86z/lfKH9HSoycK0Co8dsfHg308l018rIVmBEg8Vz3tePICR3r7gTgSvSydQQ4Wi6G9TlO9QaCqYuy3Mfo9Qs7zRpkbppt1K4hpBFRn9lilE2UyLmD097X64qPLK864ULxb6Gmkrrym9ddYkBr/ui5a/3a4ibEHy3Yo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rx4qI7n/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rx4qI7n/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDE5DC4CED7 for ; Wed, 6 Nov 2024 11:50:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730893851; bh=zKzX8IxewO2WjA9xl9/q2XAm335FISAh0Ki8XKJI/is=; h=From:To:Subject:Date:In-Reply-To:References:From; b=rx4qI7n/Fdo4iCzf4oHxO09orVQcFr7XtfNL40Llb3BxJqoojGpLcpVhyGS6PAoIa /H9RIElql9Xb6PIHlZQdTOCf2PMSg09RVr++dySjumaqX3L7+d9qjlFSjkbyXdIlfP 9Ro7Qchhq830nkg7uvahOhVqkqyv4JZcZRGyaVMvJNxp4B4eRaErbFUNpNK3Wq5Ybu kFPZs9si0qDh3U7P1dW+apetpP9o6FJm7XddL+PssD2AY8zQI4JxHtDC42WGZ+eI+W pyUyC4hArANXdzOYcipIkZUC2esa5VCnoDNtn+JXjJvfQ7rT1Ak5mZkKYmTO3IcXZc apkgMuP5DXQGw== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH 1/2] btrfs: send: check for dead send root under critical section Date: Wed, 6 Nov 2024 11:50:45 +0000 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Filipe Manana We're checking if the send root is dead without the protection of the root's root_item_lock spinlock, which is what protects the root's flags. The inverse, setting the dead flag on a root, is done under the protection of that lock, at btrfs_delete_subvolume(). Also checking and updating the root's send_in_progress counter is supposed to be done in the same critical section as checking for or setting the root dead flag, so that these operations are done atomically as a single step (which is correctly done by btrfs_delete_subvolume()). So fix this by checking if the send root is dead in the same critical section that updates the send_in_progress counter, which is protected by the root's root_item_lock spinlock. Signed-off-by: Filipe Manana --- fs/btrfs/send.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index cadb945bb345..3fcc8113641d 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -8125,6 +8125,14 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a * making it RW. This also protects against deletion. */ spin_lock(&send_root->root_item_lock); + /* + * Unlikely but possible, if the subvolume is marked for deletion but + * is slow to remove the directory entry, send can still be started. + */ + if (btrfs_root_dead(send_root)) { + spin_unlock(&send_root->root_item_lock); + return -EPERM; + } if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) { dedupe_in_progress_warn(send_root); spin_unlock(&send_root->root_item_lock); @@ -8207,15 +8215,6 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a } sctx->send_root = send_root; - /* - * Unlikely but possible, if the subvolume is marked for deletion but - * is slow to remove the directory entry, send can still be started - */ - if (btrfs_root_dead(sctx->send_root)) { - ret = -EPERM; - goto out; - } - sctx->clone_roots_cnt = arg->clone_sources_count; if (sctx->proto >= 2) {