Re: [PATCH 1/7] xfs_scrub: log operational messages when interactive

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, Feb 12, 2018 at 02:47:14PM -0600, Eric Sandeen wrote:
> On 2/5/18 5:22 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Record the output of an interactive session in the system log so that
> > future support requests can get a better picture of what happened.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> I really want to log things, but I'm conflicted about spamming syslog.
> I'm wondering if a generic /var/log/xfs.log would be good, and it could
> eventually log all xfs-related administrative actions and outcomes with
> a libfrog library helper... I don't know how non-syslog log files are
> handled in general, does everybody just roll their own?

Evidently rsyslog actually can filter things out to a separate file.
For example, /etc/rsyslog.d/20-ufw.conf:

# Log kernel generated UFW log messages to file
:msg,contains,"[UFW " /var/log/ufw.log

# Uncomment the following to stop logging anything that matches the last
# rule.  Doing this will stop logging kernel generated UFW log messages
# to the file normally containing kern.* messages (eg,
# /var/log/kern.log)
#& stop

Therefore, it looks as though we actually /can/ use the regular syslog
calls from various xfs utilities and (if rsyslog is up) forward the
output to a place where support can capture it later.

--D

> 
> I'm inclined to leave this one out of 4.15 for now while I/we think
> about the big picture here.
> 
> -Eric
> 
> > ---
> >  scrub/common.c |   37 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> > 
> > 
> > diff --git a/scrub/common.c b/scrub/common.c
> > index 17c3699..672f286 100644
> > --- a/scrub/common.c
> > +++ b/scrub/common.c
> > @@ -21,6 +21,7 @@
> >  #include <pthread.h>
> >  #include <stdbool.h>
> >  #include <sys/statvfs.h>
> > +#include <syslog.h>
> >  #include "platform_defs.h"
> >  #include "xfs.h"
> >  #include "xfs_fs.h"
> > @@ -29,6 +30,8 @@
> >  #include "common.h"
> >  #include "progress.h"
> >  
> > +extern char		*progname;
> > +
> >  /*
> >   * Reporting Status to the Console
> >   *
> > @@ -64,6 +67,12 @@ static const char *err_str[] = {
> >  	[S_PREEN]	= "Optimized",
> >  };
> >  
> > +static int log_level[] = {
> > +	[S_ERROR]	= LOG_ERR,
> > +	[S_WARN]	= LOG_WARNING,
> > +	[S_INFO]	= LOG_INFO,
> > +};
> > +
> >  /* If stream is a tty, clear to end of line to clean up progress bar. */
> >  static inline const char *stream_start(FILE *stream)
> >  {
> > @@ -73,6 +82,8 @@ static inline const char *stream_start(FILE *stream)
> >  }
> >  
> >  /* Print a warning string and some warning text. */
> > +#define LOG_BUFSZ	4096
> > +#define LOGNAME_BUFSZ	256
> >  void
> >  __str_out(
> >  	struct scrub_ctx	*ctx,
> > @@ -110,6 +121,32 @@ __str_out(
> >  		va_end(args);
> >  	}
> >  
> > +	/* If we're running interactively, log the message to syslog too. */
> > +	if (isatty(fileno(stdin)) && !debug) {
> > +		char	logname[LOGNAME_BUFSZ];
> > +
> > +		snprintf(logname, LOGNAME_BUFSZ, "%s@%s", progname,
> > +				ctx->mntpoint);
> > +		openlog(logname, LOG_PID, LOG_DAEMON);
> > +
> > +		if (error) {
> > +			syslog(LOG_ERR, "%s: %s: %s.",
> > +					_(err_str[level]), descr,
> > +					strerror_r(error, buf, DESCR_BUFSZ));
> > +		} else {
> > +			char	buf[LOG_BUFSZ];
> > +			int	sz;
> > +
> > +			sz = snprintf(buf, LOG_BUFSZ, "%s: %s: ",
> > +					_(err_str[level]), descr);
> > +			va_start(args, format);
> > +			vsnprintf(buf + sz, LOG_BUFSZ - sz, format, args);
> > +			va_end(args);
> > +			syslog(log_level[level], "%s", buf);
> > +		}
> > +		closelog();
> > +	}
> > +
> >  	if (debug)
> >  		fprintf(stream, _(" (%s line %d)"), file, line);
> >  	fprintf(stream, "\n");
> > 
> > --
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