Re: [PATCH v2 02/15] xfs: mount-api - add fs parameter description

[Ian Kent <raven@themaw.net>]

On Tue, 2019-08-27 at 08:39 -0400, Brian Foster wrote:
> On Fri, Aug 23, 2019 at 08:59:27AM +0800, Ian Kent wrote:
> > The new mount-api uses an array of struct fs_parameter_spec for
> > parameter parsing, create this table populated with the xfs mount
> > parameters.
> > 
> > The new mount-api table definition is wider than the token based
> > parameter table and interleaving the option description comments
> > between each table line is much less readable than adding them to
> > the end of each table entry. So add the option description comment
> > to each entry line even though it causes quite a few of the entries
> > to be longer than 80 characters.
> > 
> > Signed-off-by: Ian Kent <raven@themaw.net>
> > ---
> >  fs/xfs/xfs_super.c |   48
> > +++++++++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 45 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > index f9450235533c..74c88b92ce22 100644
> > --- a/fs/xfs/xfs_super.c
> > +++ b/fs/xfs/xfs_super.c
> > @@ -38,6 +38,8 @@
> >  
> >  #include <linux/magic.h>
> >  #include <linux/parser.h>
> > +#include <linux/fs_context.h>
> > +#include <linux/fs_parser.h>
> >  
> >  static const struct super_operations xfs_super_operations;
> >  struct bio_set xfs_ioend_bioset;
> > @@ -47,9 +49,6 @@ static struct kset *xfs_kset;		/* top-
> > level xfs sysfs dir */
> >  static struct xfs_kobj xfs_dbg_kobj;	/* global debug sysfs
> > attrs */
> >  #endif
> >  
> > -/*
> > - * Table driven mount option parser.
> > - */
> 
> Not sure why this is comment is removed here if the associated code
> is
> staying put in this patch..?
> 
> >  enum {
> >  	Opt_logbufs, Opt_logbsize, Opt_logdev, Opt_rtdev, Opt_biosize,
> >  	Opt_wsync, Opt_noalign, Opt_swalloc, Opt_sunit, Opt_swidth,
> > Opt_nouuid,
> > @@ -109,6 +108,49 @@ static const match_table_t tokens = {
> >  	{Opt_err,	NULL},
> >  };
> >  
> > +static const struct fs_parameter_spec xfs_param_specs[] = {
> > + fsparam_u32	("logbufs",    Opt_logbufs),   /* number of XFS
> > log buffers */
> > + fsparam_string ("logbsize",   Opt_logbsize),  /* size of XFS log
> > buffers */
> > + fsparam_string ("logdev",     Opt_logdev),    /* log device */
> > + fsparam_string ("rtdev",      Opt_rtdev),     /* realtime I/O
> > device */
> > + fsparam_u32	("biosize",    Opt_biosize),   /* log2 of
> > preferred buffered io size */
> 
> Hmm.. it looks like the difference between numerical values as
> strings
> vs. numeric types is whether we support things like unit suffixes
> (i.e.
> "64k"). That said, Opt_biosize uses suffix_kstrtoint() similar to
> Opt_logbsize yet is defined here as a u32 (and Opt_allocsize falls
> into
> the same parsing code but is a string). Is that wrong or am I just
> missing something wrt to the type specifiers here?

Right, the distinction appeared to be between those that use a human
unit (like 64k etc.) and those that don't.

Opt_biosize looked different in that it's described to be "log2 of
preferred buffered io size" so I don't think it can be given as a
human unit and that also appeared to be the case from the original
options table.

Do I need to change this somehow?

> 
> Brian
> 
> > + fsparam_flag	("wsync",      Opt_wsync),     /* safe-mode nfs
> > compatible mount */
> > + fsparam_flag	("noalign",    Opt_noalign),   /* turn off
> > stripe alignment */
> > + fsparam_flag	("swalloc",    Opt_swalloc),   /* turn on
> > stripe width allocation */
> > + fsparam_u32	("sunit",      Opt_sunit),     /* data volume
> > stripe unit */
> > + fsparam_u32	("swidth",     Opt_swidth),    /* data volume
> > stripe width */
> > + fsparam_flag	("nouuid",     Opt_nouuid),    /* ignore
> > filesystem UUID */
> > + fsparam_flag_no("grpid",      Opt_grpid),     /* group-ID from
> > parent directory (or not) */
> > + fsparam_flag	("bsdgroups",  Opt_bsdgroups), /* group-ID from
> > parent directory */
> > + fsparam_flag	("sysvgroups", Opt_sysvgroups),/* group-ID from
> > current process */
> > + fsparam_string ("allocsize",  Opt_allocsize), /* preferred
> > allocation size */
> > + fsparam_flag	("norecovery", Opt_norecovery),/* don't run XFS
> > recovery */
> > + fsparam_flag	("inode64",    Opt_inode64),   /* inodes can be
> > allocated anywhere */
> > + fsparam_flag	("inode32",    Opt_inode32),   /* inode
> > allocation limited to XFS_MAXINUMBER_32 */
> > + fsparam_flag_no("ikeep",      Opt_ikeep),     /* do not free (or
> > keep) empty inode clusters */
> > + fsparam_flag_no("largeio",    Opt_largeio),   /* report (or do
> > not report) large I/O sizes in stat() */
> > + fsparam_flag_no("attr2",      Opt_attr2),     /* do (or do not)
> > use attr2 attribute format */
> > + fsparam_flag	("filestreams",Opt_filestreams), /* use
> > filestreams allocator */
> > + fsparam_flag_no("quota",      Opt_quota),     /* disk quotas
> > (user) */
> > + fsparam_flag	("usrquota",   Opt_usrquota),  /* user quota
> > enabled */
> > + fsparam_flag	("grpquota",   Opt_grpquota),  /* group quota
> > enabled */
> > + fsparam_flag	("prjquota",   Opt_prjquota),  /* project quota
> > enabled */
> > + fsparam_flag	("uquota",     Opt_uquota),    /* user quota
> > (IRIX variant) */
> > + fsparam_flag	("gquota",     Opt_gquota),    /* group quota
> > (IRIX variant) */
> > + fsparam_flag	("pquota",     Opt_pquota),    /* project quota
> > (IRIX variant) */
> > + fsparam_flag	("uqnoenforce",Opt_uqnoenforce), /* user quota
> > limit enforcement */
> > + fsparam_flag	("gqnoenforce",Opt_gqnoenforce), /* group quota
> > limit enforcement */
> > + fsparam_flag	("pqnoenforce",Opt_pqnoenforce), /* project
> > quota limit enforcement */
> > + fsparam_flag	("qnoenforce", Opt_qnoenforce),  /* same as
> > uqnoenforce */
> > + fsparam_flag_no("discard",    Opt_discard),   /* Do (or do not)
> > not discard unused blocks */
> > + fsparam_flag	("dax",	       Opt_dax),       /* Enable
> > direct access to bdev pages */
> > + {}
> > +};
> > +
> > +static const struct fs_parameter_description xfs_fs_parameters = {
> > +	.name		= "XFS",
> > +	.specs		= xfs_param_specs,
> > +};
> >  
> >  STATIC int
> >  suffix_kstrtoint(const substring_t *s, unsigned int base, int
> > *res)
> >