On Fri, Feb 19, 2016 at 02:34:52PM +0100, Jan Tulak wrote: > Hi guys, > > what is the meaning of XLOG_MIN_RECORD_BSIZE in libxfs/xfs_log_format.h? > It is not used anywhere. I thought it might be related to -l su/sunit > option, but seeing tests with -l su=4096 (the macro is set to 16k), it > looks more like a forgotten value. > It's the minimum log buffer size allowed in the kernel. It's used in xfs_super.c at mount time to validate the logbsize option: if (mp->m_logbsize != -1 && mp->m_logbsize != 0 && (mp->m_logbsize < XLOG_MIN_RECORD_BSIZE || mp->m_logbsize > XLOG_MAX_RECORD_BSIZE || !is_power_of_2(mp->m_logbsize))) { xfs_warn(mp, "invalid logbufsize: %d [not 16k,32k,64k,128k or 256k]", mp->m_logbsize); return -EINVAL; } I suspect it's not relevant in userspace. > There is no check for a minimal value, so I can do -l su=1 (or su=0). Are > there some caveats (other than performance) with such a small value? Can > it be that we are missing a check? Because > XLOG_BIG_RECORD_BSIZE > and XLOG_MAX_RECORD_BSIZE are used and the upper bound is limited... > On a quick test, it looks like mkfs just ignores certain log stripe unit values that aren't block aligned. I'd probably expect this to behave similar to the '-d su' option and complain about invalid input..? Brian > > Thanks. > > Cheers, > Jan > > -- > Jan Tulak > jtulak@xxxxxxxxxx / jan@xxxxxxxx > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs