From 8f412efbb8bb57fde0f924a7ad084f1c536c4a0b Mon Sep 17 00:00:00 2001
From: Fam Zheng <famz@redhat.com>
Date: Tue, 20 Jan 2015 03:42:13 +0100
Subject: [PATCH 06/16] iscsi: Refuse to open as writable if the LUN is write
protected
Message-id: <1421725333-27072-1-git-send-email-famz@redhat.com>
Patchwork-id: 63370
O-Subject: [RHEL-7.2 qemu-kvm PATCH v2] iscsi: Refuse to open as writable if the LUN is write protected
Bugzilla: 1032412
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
Before, when a write protected iSCSI target is attached as scsi-disk
with BDRV_O_RDWR, we report it as writable, while in fact all writes
will fail.
One way to improve this is to report write protect flag as true to
guest, but a even better way is to refuse using a write protected LUN to
guest.
Target write protect flag is checked with a mode sense query.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit c1d4096b0f033d0a52c542f0948403783c3682e9)
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Conflicts:
block/iscsi.c
Trivial context conflict: AioContext attach/detach functions are not
present in downstream.
---
block/iscsi.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/block/iscsi.c b/block/iscsi.c
index 4f42f29..3d61dd7 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1290,6 +1290,41 @@ fail:
return NULL;
}
+
+static bool iscsi_is_write_protected(IscsiLun *iscsilun)
+{
+ struct scsi_task *task;
+ struct scsi_mode_sense *ms = NULL;
+ bool wrprotected = false;
+
+ task = iscsi_modesense6_sync(iscsilun->iscsi, iscsilun->lun,
+ 1, SCSI_MODESENSE_PC_CURRENT,
+ 0x3F, 0, 255);
+ if (task == NULL) {
+ error_report("iSCSI: Failed to send MODE_SENSE(6) command: %s",
+ iscsi_get_error(iscsilun->iscsi));
+ goto out;
+ }
+
+ if (task->status != SCSI_STATUS_GOOD) {
+ error_report("iSCSI: Failed MODE_SENSE(6), LUN assumed writable");
+ goto out;
+ }
+ ms = scsi_datain_unmarshall(task);
+ if (!ms) {
+ error_report("iSCSI: Failed to unmarshall MODE_SENSE(6) data: %s",
+ iscsi_get_error(iscsilun->iscsi));
+ goto out;
+ }
+ wrprotected = ms->device_specific_parameter & 0x80;
+
+out:
+ if (task) {
+ scsi_free_scsi_task(task);
+ }
+ return wrprotected;
+}
+
/*
* We support iscsi url's on the form
* iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
@@ -1405,6 +1440,14 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
scsi_free_scsi_task(task);
task = NULL;
+ /* Check the write protect flag of the LUN if we want to write */
+ if (iscsilun->type == TYPE_DISK && (flags & BDRV_O_RDWR) &&
+ iscsi_is_write_protected(iscsilun)) {
+ error_setg(errp, "Cannot open a write protected LUN as read-write");
+ ret = -EACCES;
+ goto out;
+ }
+
iscsi_readcapacity_sync(iscsilun, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
--
1.8.3.1