47 lines
1.6 KiB
Diff
47 lines
1.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Olaf Faaland <faaland1@llnl.gov>
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Date: Tue, 20 Feb 2018 17:33:51 -0800
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Subject: [PATCH] Detect long config lock acquisition in mmp
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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If something holds the config lock as a writer for too long, MMP will
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fail to issue MMP writes in a timely manner. This will result either in
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the pool being suspended, or in an extreme case, in the pool not being
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protected.
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If the time to acquire the config lock exceeds 1/10 of the minimum
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zfs_multihost_interval, report it in the zfs debug log.
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Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
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Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
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Closes #7212
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(cherry picked from commit c17922b8a9db00ad7e7d59a5ff975b2a1edcf887)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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module/zfs/mmp.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/module/zfs/mmp.c b/module/zfs/mmp.c
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index ee8e9201b..634e48287 100644
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--- a/module/zfs/mmp.c
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+++ b/module/zfs/mmp.c
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@@ -323,7 +323,13 @@ mmp_write_uberblock(spa_t *spa)
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int label;
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uint64_t offset;
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+ hrtime_t lock_acquire_time = gethrtime();
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spa_config_enter(spa, SCL_STATE, mmp_tag, RW_READER);
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+ lock_acquire_time = gethrtime() - lock_acquire_time;
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+ if (lock_acquire_time > (MSEC2NSEC(MMP_MIN_INTERVAL) / 10))
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+ zfs_dbgmsg("SCL_STATE acquisition took %llu ns\n",
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+ (u_longlong_t)lock_acquire_time);
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+
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vd = mmp_random_leaf(spa->spa_root_vdev);
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if (vd == NULL) {
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spa_config_exit(spa, SCL_STATE, FTAG);
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--
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2.14.2
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