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scsi: always send valid PREEMPT TYPE field

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The SPC-6 specification says that the PREEMPT service action ignores the
TYPE field when there is no reservation. However, the LIO Linux iSCSI
target rejects commands with a zero TYPE field. The field never ends up
being used in this case, so replace it with a "valid" value to work
around the issue.

Reported-by: Qing Wang <qinwang@redhat.com>
Buglink: https://redhat.atlassian.net/browse/RHEL-155807
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20260401171927.396672-3-stefanha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Stefan Hajnoczi
2026-04-01 13:19:26 -04:00
committed by Paolo Bonzini
parent 15c57ac351
commit 15a202656c
2 changed files with 20 additions and 0 deletions
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10
hw/scsi/scsi-generic.c
View File

@@ -453,6 +453,16 @@ static bool scsi_generic_pr_preempt(SCSIDevice *s, uint64_t key,
uint64_t key_be = cpu_to_be64(key);
int ret;
/*
* The LIO iSCSI target in Linux up to at least version 7.0 rejects PREEMPT
* commands with a zero TYPE field although the SPC-6 specification says
* the field should be ignored when there is no persistent reservation.
* Work around this by choosing an arbitrary valid PR type value.
*/
if (resv_type == 0) {
resv_type = PR_TYPE_WRITE_EXCLUSIVE;
}
cmd[0] = PERSISTENT_RESERVE_OUT;
cmd[1] = PRO_PREEMPT;
cmd[2] = resv_type & 0xf;

10
include/scsi/constants.h
View File

@@ -340,4 +340,14 @@
#define PRO_REGISTER_AND_MOVE 0x07
#define PRO_REPLACE_LOST_RESERVATION 0x08
/*
* Persistent reservation types
*/
#define PR_TYPE_WRITE_EXCLUSIVE 0x1
#define PR_TYPE_EXCLUSIVE_ACCESS 0x3
#define PR_TYPE_WRITE_EXCLUSIVE_REG_ONLY 0x5
#define PR_TYPE_EXCLUSIVE_ACCESS_REG_ONLY 0x6
#define PR_TYPE_WRITE_EXCLUSIVE_ALL_REGS 0x7
#define PR_TYPE_EXCLUSIVE_ACCESS_ALL_REGS 0x8
#endif