Support size option when creating tmpfs volumes

Fixes: https://github.com/containers/podman/issues/20449

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

docs/source/markdown/podman-volume-create.1.md

@@ -55,7 +55,10 @@ The `o` option sets options for the mount, and is equivalent to the filesystem
 options (also `-o`) passed to **mount(8)** with the following 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, the `inodes` option to set the maximum number of inodes for the volume and `noquota` to completely disable quota support even for tracking of disk usage. Currently these flags are only supported on "xfs" file system mounted with the `prjquota` flag described in the **xfs_quota(8)** man page.
+  - The `o` option supports the `size` option to set the maximum size of the created volume, the `inodes` option to set the maximum number of inodes for the volume, and `noquota` to completely disable quota support even for tracking of disk usage.
+  The `size` option is supported on the "tmpfs" and "xfs[note]" file systems.
+  The `inodes` option is supported on the "xfs[note]" file systems.
+  Note: xfs filesystems must be mounted with the `prjquota` flag described in the **xfs_quota(8)** man page. Podman will throw an error if they're not.
   - The `o` option supports using volume options other than the UID/GID options with the **local** driver and requires root privileges.
   - The `o` options supports the `timeout` option which allows users to set a driver specific timeout in seconds before volume creation fails. For example, **--opt=o=timeout=10** sets a driver timeout of 10 seconds.
 
@@ -75,7 +78,7 @@ $ podman volume create
 
 $ podman volume create --label foo=bar myvol
 
-# podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=nodev,noexec myvol
+# podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=size=2M,nodev,noexec myvol
 
 # podman volume create --opt device=tmpfs --opt type=tmpfs --opt o=uid=1000,gid=1000 testvol
 

libpod/runtime_volume_common.go

@@ -178,28 +178,31 @@ func (r *Runtime) newVolume(ctx context.Context, noCreatePluginVolume bool, opti
 		if err := LabelVolumePath(fullVolPath, volume.config.MountLabel); err != nil {
 			return nil, err
 		}
-		if volume.config.DisableQuota {
+		switch {
+		case volume.config.DisableQuota:
 			if volume.config.Size > 0 || volume.config.Inodes > 0 {
 				return nil, errors.New("volume options size and inodes cannot be used without quota")
 			}
-		} else {
+		case volume.config.Options["type"] == define.TypeTmpfs:
+			// tmpfs only supports Size
+			if volume.config.Inodes > 0 {
+				return nil, errors.New("volume option inodes not supported on tmpfs filesystem")
+			}
+		case volume.config.Inodes > 0 || volume.config.Size > 0:
 			projectQuotaSupported := false
 			q, err := quota.NewControl(r.config.Engine.VolumePath)
 			if err == nil {
 				projectQuotaSupported = true
 			}
-			quota := quota.Quota{}
-			if volume.config.Size > 0 || volume.config.Inodes > 0 {
-				if !projectQuotaSupported {
-					return nil, errors.New("volume options size and inodes not supported. Filesystem does not support Project Quota")
-				}
-				quota.Size = volume.config.Size
-				quota.Inodes = volume.config.Inodes
+			if !projectQuotaSupported {
+				return nil, errors.New("volume options size and inodes not supported. Filesystem does not support Project Quota")
 			}
-			if projectQuotaSupported {
-				if err := q.SetQuota(fullVolPath, quota); err != nil {
-					return nil, fmt.Errorf("failed to set size quota size=%d inodes=%d for volume directory %q: %w", volume.config.Size, volume.config.Inodes, fullVolPath, err)
-				}
+			quota := quota.Quota{
+				Inodes: volume.config.Inodes,
+				Size:   volume.config.Size,
+			}
+			if err := q.SetQuota(fullVolPath, quota); err != nil {
+				return nil, fmt.Errorf("failed to set size quota size=%d inodes=%d for volume directory %q: %w", volume.config.Size, volume.config.Inodes, fullVolPath, err)
 			}
 		}
 

test/system/160-volumes.bats

@@ -431,11 +431,14 @@ EOF
 
 @test "podman volume type=tmpfs" {
     myvolume=myvol$(random_string)
-    run_podman volume create -o type=tmpfs -o device=tmpfs $myvolume
+    run_podman volume create -o type=tmpfs -o o=size=2M -o device=tmpfs $myvolume
     is "$output" "$myvolume" "should successfully create myvolume"
 
     run_podman run --rm -v $myvolume:/vol $IMAGE stat -f -c "%T" /vol
     is "$output" "tmpfs" "volume should be tmpfs"
+
+    run_podman run --rm -v $myvolume:/vol $IMAGE sh -c "mount| grep /vol"
+    is "$output" "tmpfs on /vol type tmpfs.*size=2048k.*" "size should be set to 2048k"
 }
 
 # Named volumes copyup