From 6508e23a5053680509754d719a19b04754e1fbdc Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Thu, 10 Jan 2019 12:44:38 +0000
Subject: [PATCH 08/14] gluster: Support auto-read-only option

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20190110124442.30132-9-kwolf@redhat.com>
Patchwork-id: 83959
O-Subject: [RHEL-8.0 qemu-kvm PATCH 08/12] gluster: Support auto-read-only option
Bugzilla: 1644996
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Eric Blake <eblake@redhat.com>

If read-only=off, but auto-read-only=on is given, open the file
read-write if we have the permissions, but instead of erroring out for
read-only files, just degrade to read-only.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
(cherry picked from commit 54ea21bd16202c4a3e43c67b573b5d1aa2ec1c0c)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/gluster.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/block/gluster.c b/block/gluster.c
index cecfe09..8c13002 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -849,8 +849,16 @@ static int qemu_gluster_open(BlockDriverState *bs,  QDict *options,
     qemu_gluster_parse_flags(bdrv_flags, &open_flags);
 
     s->fd = glfs_open(s->glfs, gconf->path, open_flags);
-    if (!s->fd) {
-        ret = -errno;
+    ret = s->fd ? 0 : -errno;
+
+    if (ret == -EACCES || ret == -EROFS) {
+        /* Try to degrade to read-only, but if it doesn't work, still use the
+         * normal error message. */
+        if (bdrv_apply_auto_read_only(bs, NULL, NULL) == 0) {
+            open_flags = (open_flags & ~O_RDWR) | O_RDONLY;
+            s->fd = glfs_open(s->glfs, gconf->path, open_flags);
+            ret = s->fd ? 0 : -errno;
+        }
     }
 
     s->supports_seek_data = qemu_gluster_test_seek(s->fd);
-- 
1.8.3.1