Re: [PATCH] design: Document project quota inode

[Carlos Maiolino <cmaiolino@redhat.com>]

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>
> ---
>  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.

This is mostly ok, but I wonder we the V5 behavior should be emphasized, instead
of V4 behavior?


>  
>  * 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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-- 
Carlos