From 9e527bd9df162b9af555106675efdb909164051e Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Mon, 18 Jun 2018 16:12:05 +0200 Subject: [PATCH 038/268] block: BLK_PERM_WRITE includes ..._UNCHANGED RH-Author: Max Reitz Message-id: <20180618161212.14444-4-mreitz@redhat.com> Patchwork-id: 80763 O-Subject: [RHV-7.6 qemu-kvm-rhev PATCH 03/10] block: BLK_PERM_WRITE includes ..._UNCHANGED Bugzilla: 1518738 RH-Acked-by: John Snow RH-Acked-by: Kevin Wolf RH-Acked-by: Miroslav Rezanina Currently we never actually check whether the WRITE_UNCHANGED permission has been taken for unchanging writes. But the one check that is commented out checks both WRITE and WRITE_UNCHANGED; and considering that WRITE_UNCHANGED is already documented as being weaker than WRITE, we should probably explicitly document WRITE to include WRITE_UNCHANGED. Signed-off-by: Max Reitz Reviewed-by: Stefan Hajnoczi Reviewed-by: Alberto Garcia Message-id: 20180421132929.21610-3-mreitz@redhat.com Reviewed-by: Kevin Wolf Signed-off-by: Max Reitz (cherry picked from commit 24b7c538fea86b598e2a335f4805a0ab50a30e98) Signed-off-by: Max Reitz Signed-off-by: Miroslav Rezanina --- include/block/block.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/block/block.h b/include/block/block.h index cdec363..397b5e8 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -205,6 +205,9 @@ enum { * This permission (which is weaker than BLK_PERM_WRITE) is both enough and * required for writes to the block node when the caller promises that * the visible disk content doesn't change. + * + * As the BLK_PERM_WRITE permission is strictly stronger, either is + * sufficient to perform an unchanging write. */ BLK_PERM_WRITE_UNCHANGED = 0x04, -- 1.8.3.1