On Tue, Aug 26, 2025 at 07:54:42AM -0700, Darrick J. Wong wrote: > On Tue, Aug 26, 2025 at 02:23:12PM +0200, cem@xxxxxxxxxx wrote: > > From: Carlos Maiolino <cem@xxxxxxxxxx> > > > > Valid values for logbsize depends on whether log_sunit is set > > on the filesystem or not and if logbsize is manually set or not. > > > > When manually set, logbsize must be one of the speficied values - > > 32k to 256k inclusive in power-of-to increments. And, the specified > > value must also be a multiple of log_sunit. > > > > The default configuration for v2 logs uses a relaxed restriction, > > setting logbsize to log_sunit, independent if it is one of the valid > > values or not - also implicitly ignoring the power of two restriction. > > > > Instead of changing valid possible values for logbsize, increasing the > > testing matrix and allowing users to use some dubious configuration, > > just update the man page to describe this difference in behavior when > > manually setting logbsize or leave it to defaults. > > > > This has originally been found by an user attempting to manually set > > logbsize to the same value picked by the default configuration just so > > to receive an error message as result. > > > > Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx> > > --- > > man/man5/xfs.5 | 12 +++++++----- > > 1 file changed, 7 insertions(+), 5 deletions(-) > > > > diff --git a/man/man5/xfs.5 b/man/man5/xfs.5 > > index f9c046d4721a..b2069d17b0fe 100644 > > --- a/man/man5/xfs.5 > > +++ b/man/man5/xfs.5 > > @@ -246,16 +246,18 @@ controls the size of each buffer and so is also relevant to > > this case. > > .TP > > .B logbsize=value > > -Set the size of each in-memory log buffer. The size may be > > +Set the size of each in-memory log buffer. The size may be > > specified in bytes, or in kibibytes (KiB) with a "k" suffix. > > +If set manually, logbsize must be one of the specified valid > > +sizes and a multiple of the log stripe unit - configured at mkfs time. > > +.sp > > Valid sizes for version 1 and version 2 logs are 16384 (value=16k) > > and 32768 (value=32k). Valid sizes for version 2 logs also > > -include 65536 (value=64k), 131072 (value=128k) and 262144 (value=256k). The > > -logbsize must be an integer multiple of the log > > -stripe unit configured at mkfs time. > > +include 65536 (value=64k), 131072 (value=128k) and 262144 (value=256k). > > .sp > > The default value for version 1 logs is 32768, while the > > -default value for version 2 logs is max(32768, log_sunit). > > +default value for version 2 logs is max(32768, log_sunit) even if > > +log_sunit does not match one of the valid values above. > > Weird, but as a documentation stopgap until someone figures out if > there are any bad effects of non-power-of-2 logbsizes, > Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx> My point indeed :) > > --D > > > .TP > > .BR logdev=device " and " rtdev=device > > Use an external log (metadata journal) and/or real-time device. > > -- > > 2.51.0 > > > > >
