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Message-ID: <ce97939e-c721-2d56-93a4-dc3042b55204@huawei.com>
Date:   Mon, 14 Nov 2022 09:59:22 +0800
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Subject: Re: [PATCH v3] nfs-blkmapd: PID file read by systemd failed
To:     Steve Dickson <steved@redhat.com>
CC:     <linux-nfs@vger.kernel.org>, linfeilong <linfeilong@huawei.com>,
        <liuzhiqiang26@huawei.com>
References: <c0bd54a6-ff27-ccf7-39b4-a823996bd5af@huawei.com>
 <8b3c6919-b4a5-9136-933c-45c352908212@redhat.com>
From:   zhanchengbin <zhanchengbin1@huawei.com>
In-Reply-To: <8b3c6919-b4a5-9136-933c-45c352908212@redhat.com>
Precedence: bulk

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I don't know why it's going wrong, but I always use the latest
code and then git format-patch.
Thanks.

  -zhanchengbin.

On 2022/11/9 3:59, Steve Dickson wrote:
> Hey!
> 
> Again thank you make those changes but once again
> nothing applies cleanly... I think your email client
> is reformatting the patch. Please try this:
> 
> $ git clone git://linux-nfs.org/~steved/nfs-utils
> $ cd nfs-utils
> $ edit utils/blkmapd/device-discovery.c
> $ git commit -s -a
> $ git format-patch -o /tmp/ -1
> $ git send-email $DRYRUN  --suppress-cc=all --suppress-from \
>     --no-chain-reply-to \
>     --from "zhanchengbin <zhanchengbin1@huawei.com>" \
>     --to "Linux NFS Mailing list <linux-nfs@vger.kernel.org>"
> 
> If DRYRUN=--dry-run will test the mailing but not send it.
> 
> steved.
> 
> On 11/7/22 10:41 PM, zhanchengbin wrote:
>> When started nfs-blkmap.service, the PID file can't be opened, The
>> cause is that the child process does not create the PID file before
>> the systemd reads the PID file.
>> Adding "ExecStartPost=/bin/sleep 0.1" to
>> /usr/lib/systemd/system/nfs-blkmap.service will probably solve this
>> problem, However, there is no guarantee that the above solutions are
>> effective under high cpu pressure.So replace the daemon function with
>> the fork function, and put the behavior of creating the PID file in
>> the parent process to solve the above problems.
>>
>> Signed-off-by: zhanchengbin <zhanchengbin1@huawei.com>
>> Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
>> ---
>> V2->V3:
>>   Replace "fprintf(stderr" with BL_LOG_ERR.
>>
>>   utils/blkmapd/device-discovery.c | 48 +++++++++++++++++++++-----------
>>   1 file changed, 32 insertions(+), 16 deletions(-)
>>
>> diff --git a/utils/blkmapd/device-discovery.c 
>> b/utils/blkmapd/device-discovery.c
>> index bd890598..a565fdbd 100644
>> --- a/utils/blkmapd/device-discovery.c
>> +++ b/utils/blkmapd/device-discovery.c
>> @@ -498,28 +498,44 @@ int main(int argc, char **argv)
>>       if (fg) {
>>           openlog("blkmapd", LOG_PERROR, 0);
>>       } else {
>> -        if (daemon(0, 0) != 0) {
>> -            fprintf(stderr, "Daemonize failed\n");
>> +        pid_t pid = fork();
>> +        if (pid < 0) {
>> +            BL_LOG_ERR("fork error\n");
>>               exit(1);
>> +        } else if (pid != 0) {
>> +            pidfd = open(PID_FILE, O_WRONLY | O_CREAT, 0644);
>> +            if (pidfd < 0) {
>> +                BL_LOG_ERR("Create pid file %s failed\n", PID_FILE);
>> +                exit(1);
>> +            }
>> +
>> +            if (lockf(pidfd, F_TLOCK, 0) < 0) {
>> +                BL_LOG_ERR("Already running; Exiting!");
>> +                close(pidfd);
>> +                exit(1);
>> +            }
>> +            if (ftruncate(pidfd, 0) < 0)
>> +                BL_LOG_ERR("ftruncate on %s failed: m\n", PID_FILE);
>> +            sprintf(pidbuf, "%d\n", pid);
>> +            if (write(pidfd, pidbuf, strlen(pidbuf)) != 
>> (ssize_t)strlen(pidbuf))
>> +                BL_LOG_ERR("write on %s failed: m\n", PID_FILE);
>> +            exit(0);
>>           }
>>
>> -        openlog("blkmapd", LOG_PID, 0);
>> -        pidfd = open(PID_FILE, O_WRONLY | O_CREAT, 0644);
>> -        if (pidfd < 0) {
>> -            BL_LOG_ERR("Create pid file %s failed\n", PID_FILE);
>> -            exit(1);
>> +        (void)setsid();
>> +        if (chdir("/")) {
>> +            BL_LOG_ERR("chdir error\n");
>>           }
>> +        int fd = open("/dev/null", O_RDWR, 0);
>> +        if (fd >= 0) {
>> +            (void)dup2(fd, STDIN_FILENO);
>> +            (void)dup2(fd, STDOUT_FILENO);
>> +            (void)dup2(fd, STDERR_FILENO);
>>
>> -        if (lockf(pidfd, F_TLOCK, 0) < 0) {
>> -            BL_LOG_ERR("Already running; Exiting!");
>> -            close(pidfd);
>> -            exit(1);
>> +            (void)close(fd);
>>           }
>> -        if (ftruncate(pidfd, 0) < 0)
>> -            BL_LOG_WARNING("ftruncate on %s failed: m\n", PID_FILE);
>> -        sprintf(pidbuf, "%d\n", getpid());
>> -        if (write(pidfd, pidbuf, strlen(pidbuf)) != 
>> (ssize_t)strlen(pidbuf))
>> -            BL_LOG_WARNING("write on %s failed: m\n", PID_FILE);
>> +
>> +        openlog("blkmapd", LOG_PID, 0);
>>       }
>>
>>       signal(SIGINT, sig_die);
> 
> .
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