From patchwork Fri Jun 26 15:04:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 11627729 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8042392A for ; Fri, 26 Jun 2020 15:05:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A0F02080C for ; Fri, 26 Jun 2020 15:05:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593183904; bh=9i6P/z6NfUDRDD46kUh4BiJshxJZ3hX+mLCM84PbP5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NkHB+GxV1buSoXMBWCHaYCHw3dFiDGXTY6ixcEI9Imz99yoHjzcOJQ4PFA7T20iLK gcID/Ag9ZnmjAhuWcE8yw31osPK4JBIPdmaGvIS2dKuCXWVnH0ITmBDqRfJHCIgXeP 7Sz9AxchON8t+r7uNxuB6sAzUlMpVPvoAeFkQzwo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728105AbgFZPFD (ORCPT ); Fri, 26 Jun 2020 11:05:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:57034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726359AbgFZPFD (ORCPT ); Fri, 26 Jun 2020 11:05:03 -0400 Received: from tleilax.com (68-20-15-154.lightspeed.rlghnc.sbcglobal.net [68.20.15.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E0C920706; Fri, 26 Jun 2020 15:05:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593183903; bh=9i6P/z6NfUDRDD46kUh4BiJshxJZ3hX+mLCM84PbP5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GXqiI471a/lTlWu3I94Wn4KbKsuG5UlLpwpLNCLcnVLLkGbJfPhPAoA+hDsB9l+Qk kGWoGlGzukCPdvluiFFW2ZswDMDOxGa7lqk+EeUV5QW+zw+sxEcID7Nm3IXAtTR4vA IJDjGoVlB0DSNh8HNdUh4I3UF7rWDOTJgvDYu9U4= From: Jeff Layton To: dhowells@redhat.com Cc: linux-fsdevel@vger.kernel.org, andres@anarazel.de Subject: [fsinfo PATCH v2 1/3] errseq: add a new errseq_scrape function Date: Fri, 26 Jun 2020 11:04:58 -0400 Message-Id: <20200626150500.565417-2-jlayton@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200626150500.565417-1-jlayton@kernel.org> References: <20200626150500.565417-1-jlayton@kernel.org> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Jeff Layton To grab the current value of an errseq_t, mark it as seen and then return the value with the seen bit masked off. Signed-off-by: Jeff Layton Reviewed-by: David Howells Reviewed-by: Carlos Maiolino --- include/linux/errseq.h | 1 + lib/errseq.c | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/include/linux/errseq.h b/include/linux/errseq.h index fc2777770768..de165623fa86 100644 --- a/include/linux/errseq.h +++ b/include/linux/errseq.h @@ -9,6 +9,7 @@ typedef u32 errseq_t; errseq_t errseq_set(errseq_t *eseq, int err); errseq_t errseq_sample(errseq_t *eseq); +errseq_t errseq_scrape(errseq_t *eseq); int errseq_check(errseq_t *eseq, errseq_t since); int errseq_check_and_advance(errseq_t *eseq, errseq_t *since); #endif diff --git a/lib/errseq.c b/lib/errseq.c index 81f9e33aa7e7..8ded0920eed3 100644 --- a/lib/errseq.c +++ b/lib/errseq.c @@ -108,7 +108,7 @@ errseq_t errseq_set(errseq_t *eseq, int err) EXPORT_SYMBOL(errseq_set); /** - * errseq_sample() - Grab current errseq_t value. + * errseq_sample() - Grab current errseq_t value (or 0 if it hasn't been seen) * @eseq: Pointer to errseq_t to be sampled. * * This function allows callers to initialise their errseq_t variable. @@ -117,7 +117,7 @@ EXPORT_SYMBOL(errseq_set); * see it the next time it checks for an error. * * Context: Any context. - * Return: The current errseq value. + * Return: The current errseq value or 0 if it wasn't previously seen */ errseq_t errseq_sample(errseq_t *eseq) { @@ -130,6 +130,35 @@ errseq_t errseq_sample(errseq_t *eseq) } EXPORT_SYMBOL(errseq_sample); +/** + * errseq_scrape() - Grab current errseq_t value + * @eseq: Pointer to errseq_t to be sampled. + * + * This function allows callers to scrape the current value of an errseq_t. + * Unlike errseq_sample, this will always return the current value with + * the SEEN flag unset, even when the value has not yet been seen. + * + * Context: Any context. + * Return: The current errseq value with ERRSEQ_SEEN masked off + */ +errseq_t errseq_scrape(errseq_t *eseq) +{ + errseq_t old = READ_ONCE(*eseq); + + /* + * For the common case of no errors ever having been set, we can skip + * marking the SEEN bit. Once an error has been set, the value will + * never go back to zero. + */ + if (old != 0) { + errseq_t new = old | ERRSEQ_SEEN; + if (old != new) + cmpxchg(eseq, old, new); + } + return old & ~ERRSEQ_SEEN; +} +EXPORT_SYMBOL(errseq_scrape); + /** * errseq_check() - Has an error occurred since a particular sample point? * @eseq: Pointer to errseq_t value to be checked.