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From d2e11da4b7fd0453e942f43e4196dc63b3dbd708 Mon Sep 17 00:00:00 2001
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From: Pawel Baldysiak <pawel.baldysiak@intel.com>
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Date: Fri, 22 Feb 2019 13:30:27 +0100
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Subject: [RHEL7.7 PATCH 19/24] mdmon: wait for previous mdmon to exit during
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takeover
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Since the patch c76242c5("mdmon: get safe mode delay file descriptor
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early"), safe_mode_dalay is set properly by initrd mdmon. But in some
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cases with filesystem traffic since the very start of the system, it
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might take a while to transit to clean state. Due to fact that new
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mdmon does not wait for the old one to exit - it might happen that the
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new one switches safe_mode_delay back to seconds, before old one exits.
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As the result two mdmons are running concurrently on same array.
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Wait for the old mdmon to exit by pinging it with SIGUSR1 signal, just
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in case it is sleeping.
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Signed-off-by: Pawel Baldysiak <pawel.baldysiak@intel.com>
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Signed-off-by: Jes Sorensen <jsorensen@fb.com>
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---
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mdmon.c | 14 +++++++++++---
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1 file changed, 11 insertions(+), 3 deletions(-)
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diff --git a/mdmon.c b/mdmon.c
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index 0955fcc..ff985d2 100644
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--- a/mdmon.c
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+++ b/mdmon.c
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@@ -171,6 +171,7 @@ static void try_kill_monitor(pid_t pid, char *devname, int sock)
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int fd;
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int n;
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long fl;
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+ int rv;
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/* first rule of survival... don't off yourself */
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if (pid == getpid())
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@@ -201,9 +202,16 @@ static void try_kill_monitor(pid_t pid, char *devname, int sock)
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fl &= ~O_NONBLOCK;
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fcntl(sock, F_SETFL, fl);
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n = read(sock, buf, 100);
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- /* Ignore result, it is just the wait that
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- * matters
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- */
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+
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+ /* If there is I/O going on it might took some time to get to
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+ * clean state. Wait for monitor to exit fully to avoid races.
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+ * Ping it with SIGUSR1 in case that it is sleeping */
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+ for (n = 0; n < 25; n++) {
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+ rv = kill(pid, SIGUSR1);
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+ if (rv < 0)
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+ break;
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+ usleep(200000);
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+ }
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}
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void remove_pidfile(char *devname)
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--
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2.7.5
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