diff options
| -rw-r--r-- | block/iscsi.c | 55 |
1 files changed, 43 insertions, 12 deletions
diff --git a/block/iscsi.c b/block/iscsi.c index 6f87605..e64659f 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -26,6 +26,7 @@ #include "config-host.h" #include <poll.h> +#include <math.h> #include <arpa/inet.h> #include "qemu-common.h" #include "qemu/config-file.h" @@ -75,6 +76,7 @@ typedef struct IscsiTask { Coroutine *co; QEMUBH *bh; IscsiLun *iscsilun; + QEMUTimer retry_timer; } IscsiTask; typedef struct IscsiAIOCB { @@ -86,7 +88,6 @@ typedef struct IscsiAIOCB { uint8_t *buf; int status; int canceled; - int retries; int64_t sector_num; int nb_sectors; #ifdef __linux__ @@ -96,7 +97,8 @@ typedef struct IscsiAIOCB { #define NOP_INTERVAL 5000 #define MAX_NOP_FAILURES 3 -#define ISCSI_CMD_RETRIES 5 +#define ISCSI_CMD_RETRIES ARRAY_SIZE(iscsi_retry_times) +static const unsigned iscsi_retry_times[] = {8, 32, 128, 512, 2048}; /* this threshhold is a trade-off knob to choose between * the potential additional overhead of an extra GET_LBA_STATUS request @@ -146,6 +148,19 @@ static void iscsi_co_generic_bh_cb(void *opaque) qemu_coroutine_enter(iTask->co, NULL); } +static void iscsi_retry_timer_expired(void *opaque) +{ + struct IscsiTask *iTask = opaque; + if (iTask->co) { + qemu_coroutine_enter(iTask->co, NULL); + } +} + +static inline unsigned exp_random(double mean) +{ + return -mean * log((double)rand() / RAND_MAX); +} + static void iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, void *command_data, void *opaque) @@ -158,14 +173,30 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, iTask->do_retry = 0; iTask->task = task; - if (iTask->retries-- > 0 && status == SCSI_STATUS_CHECK_CONDITION - && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) { - error_report("iSCSI CheckCondition: %s", iscsi_get_error(iscsi)); - iTask->do_retry = 1; - goto out; - } - if (status != SCSI_STATUS_GOOD) { + if (iTask->retries++ < ISCSI_CMD_RETRIES) { + if (status == SCSI_STATUS_CHECK_CONDITION + && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) { + error_report("iSCSI CheckCondition: %s", + iscsi_get_error(iscsi)); + iTask->do_retry = 1; + goto out; + } + if (status == SCSI_STATUS_BUSY) { + unsigned retry_time = + exp_random(iscsi_retry_times[iTask->retries - 1]); + error_report("iSCSI Busy (retry #%u in %u ms): %s", + iTask->retries, retry_time, + iscsi_get_error(iscsi)); + aio_timer_init(iTask->iscsilun->aio_context, + &iTask->retry_timer, QEMU_CLOCK_REALTIME, + SCALE_MS, iscsi_retry_timer_expired, iTask); + timer_mod(&iTask->retry_timer, + qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + retry_time); + iTask->do_retry = 1; + return; + } + } error_report("iSCSI Failure: %s", iscsi_get_error(iscsi)); } @@ -180,9 +211,9 @@ out: static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask) { *iTask = (struct IscsiTask) { - .co = qemu_coroutine_self(), - .retries = ISCSI_CMD_RETRIES, - .iscsilun = iscsilun, + .co = qemu_coroutine_self(), + .retries = ISCSI_CMD_RETRIES, + .iscsilun = iscsilun, }; } |
