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Re: [Qemu-devel] [PATCH][RESEND] iscsi: add support for iSCSI NOPs
From: |
ronnie sahlberg |
Subject: |
Re: [Qemu-devel] [PATCH][RESEND] iscsi: add support for iSCSI NOPs |
Date: |
Mon, 3 Dec 2012 21:03:41 -0800 |
Acked-By: address@hidden (Ronnie Sahlberg)
This verified that the service is actually operational and is much
more reliable than TCP-KEEPALIVES.
This is the proper way to monitor that the iscsi target is alive.
We should as a later patch add the ability to configure this via the
qemu config file instead of using hardcoded values.
regards
ronnie sahlberg
On Mon, Dec 3, 2012 at 11:34 AM, Peter Lieven <address@hidden> wrote:
> 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.
>
> Reported-by: Ronnie Sahlberg <address@hidden>
> Signed-off-by: Peter Lieven <address@hidden>
> ---
> block/iscsi.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index d0b1a10..fab4c8b 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -47,6 +47,9 @@ typedef struct IscsiLun {
> int block_size;
> uint64_t num_blocks;
> int events;
> +
> + QEMUTimer *nop_timer;
> + int nops_in_flight;
> } IscsiLun;
>
> typedef struct IscsiAIOCB {
> @@ -72,6 +75,9 @@ struct IscsiTask {
> int complete;
> };
>
> +#define NOP_INTERVAL 5000
> +#define MAX_NOP_FAILURES 3
> +
> static void
> iscsi_bh_cb(void *p)
> {
> @@ -925,6 +931,35 @@ static char *parse_initiator_name(const char *target)
> }
> }
>
> +static void iscsi_nop_cb(struct iscsi_context *iscsi, int status, void
> *command_data, void *private_data)
> +{
> + IscsiLun *iscsilun = private_data;
> +
> + if (iscsilun) {
> + iscsilun->nops_in_flight = 0;
> + }
> +}
> +
> +static void iscsi_nop_timed_event(void *opaque)
> +{
> + IscsiLun *iscsilun = opaque;
> +
> + if (iscsilun->nops_in_flight > MAX_NOP_FAILURES) {
> + error_report("iSCSI: NOP timeout. Reconnecting...");
> + iscsi_reconnect(iscsilun->iscsi);
> + iscsilun->nops_in_flight = 0;
> + }
> +
> + if (iscsi_nop_out_async(iscsilun->iscsi, iscsi_nop_cb, NULL, 0,
> iscsilun) != 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);
> + iscsilun->nops_in_flight++;
> +}
> +
> /*
> * We support iscsi url's on the form
> * iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
> @@ -1036,6 +1071,10 @@ static int iscsi_open(BlockDriverState *bs, const char
> *filename, int flags)
>
> ret = 0;
>
> + /* 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);
> +
> out:
> if (initiator_name != NULL) {
> g_free(initiator_name);
> @@ -1058,6 +1097,10 @@ 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));
> --
> 1.7.9.5
>
>