Received: (at submit) by debbugs.gnu.org; 21 Oct 2022 08:37:38 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Fri Oct 21 04:37:38 2022 Received: from localhost ([127.0.0.1]:36969 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1olnWt-0001OV-Ca for submit <at> debbugs.gnu.org; Fri, 21 Oct 2022 04:37:38 -0400 Received: from lists.gnu.org ([209.51.188.17]:50196) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <gnu@HIDDEN>) id 1olnWr-0001ON-Hg for submit <at> debbugs.gnu.org; Fri, 21 Oct 2022 04:37:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <gnu@HIDDEN>) id 1olnWf-000651-UA for bug-parted@HIDDEN; Fri, 21 Oct 2022 04:37:15 -0400 Received: from 75-101-100-43.dsl.static.fusionbroadband.com ([75.101.100.43] helo=hop.toad.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from <gnu@HIDDEN>) id 1olnWc-0007fg-VV for bug-parted@HIDDEN; Fri, 21 Oct 2022 04:37:09 -0400 Received: from hop.toad.com (localhost [127.0.0.1]) by hop.toad.com (8.12.9/8.12.9) with ESMTP id 29L8arDI016057; Fri, 21 Oct 2022 01:36:53 -0700 To: "zhanghongtao (A)" <zhanghongtao22@HIDDEN> Subject: Re: [parted-devel] [PATCH]parted: acquire flock before modifying the device superblock In-reply-to: <6a790da3-55d7-8671-ec0d-642356979a34@HIDDEN> References: <6a790da3-55d7-8671-ec0d-642356979a34@HIDDEN> Comments: In-reply-to "zhanghongtao (A)" <zhanghongtao22@HIDDEN> message dated "Mon, 17 Oct 2022 21:14:41 +0800." Date: Fri, 21 Oct 2022 01:36:53 -0700 Message-ID: <16056.1666341413@HIDDEN> From: John Gilmore <gnu@HIDDEN> Received-SPF: pass client-ip=75.101.100.43; envelope-from=gnu@HIDDEN; helo=hop.toad.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, TVD_RCVD_IP=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Spam-Score: -1.4 (-) X-Debbugs-Envelope-To: submit Cc: linfeilong@HIDDEN, parted-devel@HIDDEN, bug-parted@HIDDEN, liuzhiqiang26@HIDDEN X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -0.1 (/) Parted shouldn't lock itself (or systemd) out of concurrent access to the same device. But if there is a bug relating to concurrent "formatting a filesystem and systemd", then why not get an flock just for the duration of formatting a file system? Formatting is a write-only operation and there's no point in trying to do two of them concurrently on the same file system. John
bug-parted@HIDDEN:bug#58598; Package parted.
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From: "zhanghongtao (A)" <zhanghongtao22@HIDDEN>
Subject: [PATCH]parted: acquire flock before modifying the device superblock
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We noticed that systemd has an issue about symlink unreliable caused by
formatting filesystem and systemd operating on same device.
Issue Link: https://github.com/systemd/systemd/issues/23746
According to systemd doc, a BSD flock needs to be acquired before
formatting the device.
Related Link: https://systemd.io/BLOCK_DEVICE_LOCKING/
So we acquire flock after opening the device.
But this patch causes multiple parted processes to fail to run
simultaneously in interactive mode.
Or, can we add an option for lock mode?
Signed-off-by: Hongtao Zhang <zhanghongtao22@HIDDEN>
---
libparted/arch/linux.c | 49 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/libparted/arch/linux.c b/libparted/arch/linux.c
index f3bf14d..f7645f4 100644
--- a/libparted/arch/linux.c
+++ b/libparted/arch/linux.c
@@ -22,6 +22,7 @@
#include <linux/blkpg.h>
#include <parted/parted.h>
#include <parted/debug.h>
+#include <sys/file.h>
#if defined __s390__ || defined __s390x__
#include <parted/fdasd.h>
#endif
@@ -1706,6 +1707,50 @@ _device_open_ro (PedDevice* dev)
return rc;
}
+static int lock_blkdev (int fd, char *path)
+{
+ int rc, msg = 0;
+
+ /* Try non-block first to provide message */
+ rc = flock(fd, LOCK_EX | LOCK_NB);
+ if (rc == 0)
+ return 0;
+ if (rc != 0 && errno == EWOULDBLOCK) {
+ ped_exception_throw (
+ PED_EXCEPTION_WARNING,
+ PED_EXCEPTION_OK,
+ _("%s: device already locked, "
+ "waiting to get lock ..."),
+ path);
+ msg = 1;
+ }
+
+ rc = flock (fd, LOCK_EX);
+ if (rc != 0) {
+ switch (errno) {
+ case EWOULDBLOCK: /* LOCK_NB */
+ ped_exception_throw (
+ PED_EXCEPTION_WARNING,
+ PED_EXCEPTION_OK,
+ _("%s: device already locked"),
+ path);
+ break;
+ default:
+ ped_exception_throw (
+ PED_EXCEPTION_WARNING,
+ PED_EXCEPTION_OK,
+ _("%s: failed to get lock"),
+ path);
+ }
+ } else if (msg)
+ ped_exception_throw (
+ PED_EXCEPTION_WARNING,
+ PED_EXCEPTION_OK,
+ _("%s: lock ok"),
+ path);
+ return rc;
+}
+
static int
linux_open (PedDevice* dev)
{
@@ -1747,6 +1792,10 @@ retry:
}
} else {
dev->read_only = 0;
+ if (lock_blkdev (arch_specific->fd, dev->path) != 0) {
+ close (arch_specific->fd);
+ return 0;
+ }
}
_flush_cache (dev);
--
2.33.0
"zhanghongtao (A)" <zhanghongtao22@HIDDEN>:bug-parted@HIDDEN.
Full text available.bug-parted@HIDDEN:bug#58598; Package parted.
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