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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PH0PR04MB7416.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 394c9c22-6cb7-4e17-176e-08da58d5f26e X-MS-Exchange-CrossTenant-originalarrivaltime: 28 Jun 2022 07:15:14.4301 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: cDt5J4gN32/HVCxIdpgmVulMyGnAc7+BDX6lVNXPJeH/m2h/qZZ+mbgcQW1PJT1Z5+NQYUIU/BgFU4brJCH7nvZAG4OZMfzwCxy5hyNkBy8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR04MB6071 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 27.06.22 18:45, David Sterba wrote:=0A= > On Mon, Jun 27, 2022 at 06:51:30AM +0000, Johannes Thumshirn wrote:=0A= >> On 24.06.22 16:15, David Sterba wrote:=0A= >>> diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h=0A= >>> index 0702d4087ff6..bb449c75ee4c 100644=0A= >>> --- a/fs/btrfs/block-rsv.h=0A= >>> +++ b/fs/btrfs/block-rsv.h=0A= >>> @@ -27,7 +27,8 @@ struct btrfs_block_rsv {=0A= >>> spinlock_t lock;=0A= >>> bool full;=0A= >>> bool failfast;=0A= >>> - unsigned short type;=0A= >>> + /* Block reserve type, one of BTRFS_BLOCK_RSV_* */=0A= >>> + u8 type;=0A= >>> =0A= >>=0A= >> Is there any reason to not use the enum?=0A= > =0A= > Enum would be 'int', 4 bytes to the space optimization would be=0A= > lost. Enum types can be shortened as=0A= > =0A= > enum btrfs_reserve type:8=0A= > =0A= > but I'm not sure it's an improvement.=0A= > =0A= =0A= Using an enum would give some type safety (I think -Wenum-compare is =0A= on by default in the kernel). Packing that enum would give us the 1 byte=0A= size you're looking for.=0A=