Support size and inode options on builtin volumes

[NO TESTS NEEDED] Since it is difficult to setup xfs quota

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1982164

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

1 files changed, 38 insertions, 6 deletions

diff --git a/docs/source/markdown/podman-volume-create.1.md b/docs/source/markdown/podman-volume-create.1.md
index a06411000..9bf5a3d81 100644
--- a/docs/source/markdown/podman-volume-create.1.md
+++ b/docs/source/markdown/podman-volume-create.1.md
@@ -17,7 +17,7 @@ driver options can be set using the **--opt** flag.
 
 #### **--driver**=*driver*
 
-Specify the volume driver name (default **local**). Setting this to a value other than **local** Podman will attempt to create the volume using a volume plugin with the given name. Such plugins must be defined in the **volume_plugins** section of the **containers.conf**(5) configuration file.
+Specify the volume driver name (default **local**). Setting this to a value other than **local** Podman attempts to create the volume using a volume plugin with the given name. Such plugins must be defined in the **volume_plugins** section of the **containers.conf**(5) configuration file.
 
 #### **--help**
 
@@ -34,10 +34,14 @@ For the default driver, **local**, this allows a volume to be configured to moun
 For the `local` driver the following options are supported: `type`, `device`, and `o`.
 The `type` option sets the type of the filesystem to be mounted, and is equivalent to the `-t` flag to **mount(8)**.
 The `device` option sets the device to be mounted, and is equivalent to the `device` argument to **mount(8)**.
-The `o` option sets options for the mount, and is equivalent to the `-o` flag to **mount(8)** with two exceptions.
-The `o` option supports `uid` and `gid` options to set the UID and GID of the created volume that are not normally supported by **mount(8)**.
-Using volume options with the **local** driver requires root privileges.
-When not using the **local** driver, the given options will be passed directly to the volume plugin. In this case, supported options will be dictated by the plugin in question, not Podman.
+
+The `o` option sets options for the mount, and is equivalent to the `-o` flag to **mount(8)** with these exceptions:
+
+  - The `o` option supports `uid` and `gid` options to set the UID and GID of the created volume that are not normally supported by **mount(8)**.
+  - The `o` option supports the `size` option to set the maximum size of the created volume and the `inodes` option to set the maximum number of inodes for the volume. Currently these flags are only supported on "xfs" file system mounted with the `prjquota` flag described in the **xfs_quota(8)** man page.
+  - Using volume options other then the UID/GID options with the **local** driver requires root privileges.
+
+When not using the **local** driver, the given options are passed directly to the volume plugin. In this case, supported options are dictated by the plugin in question, not Podman.
 
 ## EXAMPLES
 
@@ -53,8 +57,36 @@ $ podman volume create --label foo=bar myvol
 # podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=uid=1000,gid=1000 testvol
 ```
 
+## QUOTAS
+
+podman volume create uses `XFS project quota controls` for controlling the size and the number of inodes of builtin volumes. The directory used to store the volumes must be an`XFS` file system and be mounted with the `pquota` option.
+
+Example /etc/fstab entry:
+```
+/dev/podman/podman-var /var xfs defaults,x-systemd.device-timeout=0,pquota 1 2
+```
+
+Podman generates project ids for each builtin volume, but these project ids need to be unique for the XFS file system. These project ids by default are generated randomly, with a potential for overlap with other quotas on the same file
+system.
+
+The xfs_quota tool can be used to assign a project id to the storage driver directory, e.g.:
+
+```
+echo 100000:/var/lib/containers/storage/overlay >> /etc/projects
+echo 200000:/var/lib/containers/storage/volumes >> /etc/projects
+echo storage:100000 >> /etc/projid
+echo volumes:200000 >> /etc/projid
+xfs_quota -x -c 'project -s storage volumes' /<xfs mount point>
+```
+
+In the example above we are configuring the overlay storage driver for newly
+created containers as well as volumes to use project ids with a **start offset**.
+All containers will be assigned larger project ids (e.g. >= 100000).
+All volume assigned project ids larger project ids starting with 200000.
+This prevents xfs_quota management conflicts with containers/storage.
+
 ## SEE ALSO
-**podman-volume**(1), **mount**(8), **containers.conf**(5)
+**podman-volume**(1), **mount**(8), **containers.conf**(5), **xfs_quota**(8), `xfs_quota(8)`, `projects(5)`, `projid(5)`
 
 ## HISTORY
 January 2020, updated with information on volume plugins by Matthew Heon <mheon@redhat.com>