Re: [PATCH] design: Document project quota inode

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

On Tue, Aug 07, 2018 at 08:10:50AM -0700, Darrick J. Wong wrote:
> On Mon, Aug 06, 2018 at 06:10:32PM -0300, Marco Benatto wrote:
> > A project quota inode was introduced into V5 superblock allowing
> > project quotas and group quotas to be used simultaneously. However
> > on "Quota Inodes" section we still mention it's not possible to
> > use project and group quotas at sametime.
> > 
> > This patch documents this behavior for V5 and later superblocks,
> > while keeps documented the old behavior for earlier versions.
> > 
> > Signed-off-by: Marco Benatto <mbenatto@redhat.com>
> 
> Looks ok,
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D
> 
> > ---
> >  design/XFS_Filesystem_Structure/internal_inodes.asciidoc | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/design/XFS_Filesystem_Structure/internal_inodes.asciidoc b/design/XFS_Filesystem_Structure/internal_inodes.asciidoc
> > index f5c2654..b694e74 100644
> > --- a/design/XFS_Filesystem_Structure/internal_inodes.asciidoc
> > +++ b/design/XFS_Filesystem_Structure/internal_inodes.asciidoc
> > @@ -8,9 +8,12 @@ accessible from the superblock.
> >  [[Quota_Inodes]]
> >  == Quota Inodes
> >  
> > -If quotas are used, two inodes are allocated for user and group quota
> > -management. If project quotas are used, these replace the group quota management
> > -and therefore uses the group quota inode.
> > +If quotas are used, prior to version 5 superblocks, two inodes are allocated for
> > +user and group management. In this case if project quotas are used, these replace
> > +the group quota management and therefore uses the group quota inode.
> > +
> > +In version 5 superblock or later a third inode will be allocated to project quota
> > +management, making it possible to use group and project quotas management simultaneously.

Ugh, /me has post-review regrets... mind if I rearrange this a little?

"Prior to version 5 filesystems, two inodes can be allocated for quota
management.  The first inode will be used for user quotas.  The second
inode will be used for group quotas or project quotas, depending on
mount options.  Group and project quotas are mutually exclusive features
in these environments.

"In version 5 or later filesystems, each quota type is allocated its own
inode, making it possible to use group and project quota management
simultaneously."

--D

> >  
> >  * Project quota's primary purpose is to track and monitor disk usage for
> >  directories. For this to occur, the directory inode must have the
> > @@ -28,7 +31,7 @@ multiplied by the size of +xfs_dqblk_t+ (136 bytes).
> >  .Quota inode layout
> >  image::images/76.png[]
> >  
> > -Quota information is stored in the data extents of the two reserved quota
> > +Quota information is stored in the data extents of the reserved quota
> >  inodes as an array of the +xfs_dqblk+ structures, where there is one array
> >  element for each ID in the system:
> >  
> > -- 
> > 2.9.5
> > 
> > --
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