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iscsi: add support for iSCSI NOPs [v2] 

This patch will send NOP-Out PDUs every 5 seconds to the iSCSI target.
If a consecutive number of NOP-In replies fail a reconnect is initiated.
iSCSI NOPs help to ensure that the connection to the target is still operational.
This should not, but in reality may be the case even if the TCP connection is still
alive if there are bugs in either the target or the initiator implementation.

v2:
 - track the NOPs inside libiscsi so libiscsi can reset the counter
   in case it initiates a reconnect.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Lieven 2012-12-06 10:46:47 +01:00 committed by Paolo Bonzini
parent 4cc841b57c
commit 5b5d34ec98
1 changed files with 38 additions and 0 deletions
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38
block/iscsi.c
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@ -48,6 +48,7 @@ typedef struct IscsiLun {
int block_size;
uint64_t num_blocks;
int events;
QEMUTimer *nop_timer;
} IscsiLun;
typedef struct IscsiAIOCB {
@ -66,6 +67,9 @@ typedef struct IscsiAIOCB {
#endif
} IscsiAIOCB;
#define NOP_INTERVAL 5000
#define MAX_NOP_FAILURES 3
static void
iscsi_bh_cb(void *p)
{
@ -768,6 +772,26 @@ static char *parse_initiator_name(const char *target)
}
}
#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
static void iscsi_nop_timed_event(void *opaque)
{
IscsiLun *iscsilun = opaque;
if (iscsi_get_nops_in_flight(iscsilun->iscsi) > MAX_NOP_FAILURES) {
error_report("iSCSI: NOP timeout. Reconnecting...");
iscsi_reconnect(iscsilun->iscsi);
}
if (iscsi_nop_out_async(iscsilun->iscsi, NULL, NULL, 0, NULL) != 0) {
error_report("iSCSI: failed to sent NOP-Out. Disabling NOP messages.");
return;
}
qemu_mod_timer(iscsilun->nop_timer, qemu_get_clock_ms(rt_clock) + NOP_INTERVAL);
iscsi_set_events(iscsilun);
}
#endif
/*
* We support iscsi url's on the form
* iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
@ -928,6 +952,12 @@ static int iscsi_open(BlockDriverState *bs, const char *filename, int flags)
ret = 0;
#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
/* Set up a timer for sending out iSCSI NOPs */
iscsilun->nop_timer = qemu_new_timer_ms(rt_clock, iscsi_nop_timed_event, iscsilun);
qemu_mod_timer(iscsilun->nop_timer, qemu_get_clock_ms(rt_clock) + NOP_INTERVAL);
#endif
out:
if (initiator_name != NULL) {
g_free(initiator_name);
@ -953,6 +983,10 @@ static void iscsi_close(BlockDriverState *bs)
IscsiLun *iscsilun = bs->opaque;
struct iscsi_context *iscsi = iscsilun->iscsi;
if (iscsilun->nop_timer) {
qemu_del_timer(iscsilun->nop_timer);
qemu_free_timer(iscsilun->nop_timer);
}
qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL, NULL);
iscsi_destroy_context(iscsi);
memset(iscsilun, 0, sizeof(IscsiLun));
@ -987,6 +1021,10 @@ static int iscsi_create(const char *filename, QEMUOptionParameter *options)
if (ret != 0) {
goto out;
}
if (iscsilun->nop_timer) {
qemu_del_timer(iscsilun->nop_timer);
qemu_free_timer(iscsilun->nop_timer);
}
if (iscsilun->type != TYPE_DISK) {
ret = -ENODEV;
goto out;