[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCHv2] block/iscsi: handle BUSY condition
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv2] block/iscsi: handle BUSY condition |
Date: |
Fri, 30 May 2014 23:36:47 +0200 |
this patch adds handling of BUSY status reponse from an iSCSI target.
Currently, we fail with -EIO in case of SCSI_STATUS_BUSY while the
obvious reaction would be to retry the operation after some time.
The retry time is randomly choosen from a range with exponential
growth increasing with each retry.
This patch includes most of the changes by a an upcoming patch
from Stefan Hajnoczi:
iscsi: implement .bdrv_detach/attach_aio_context()
because I also need the reference to the aio_context for
the retry timer to work. I included the changes to maintain
better mergeability.
Signed-off-by: Peter Lieven <address@hidden>
---
v1->v2:
- remove timer_del [Paolo]
- embed retry_timer in IscsiTask [Paolo]
- adjust distribution of random values [Paolo]
block/iscsi.c | 123 ++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 92 insertions(+), 31 deletions(-)
diff --git a/block/iscsi.c b/block/iscsi.c
index 3892cc5..f1a295c 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"
@@ -49,6 +50,7 @@
typedef struct IscsiLun {
struct iscsi_context *iscsi;
+ AioContext *aio_context;
int lun;
enum scsi_inquiry_peripheral_device_type type;
int block_size;
@@ -73,6 +75,8 @@ typedef struct IscsiTask {
struct scsi_task *task;
Coroutine *co;
QEMUBH *bh;
+ IscsiLun *iscsilun;
+ QEMUTimer retry_timer;
} IscsiTask;
typedef struct IscsiAIOCB {
@@ -95,6 +99,7 @@ typedef struct IscsiAIOCB {
#define NOP_INTERVAL 5000
#define MAX_NOP_FAILURES 3
#define ISCSI_CMD_RETRIES 5
+static const unsigned iscsi_retry_times[] = {4, 16, 64, 256, 1024, 4096};
/* this threshhold is a trade-off knob to choose between
* the potential additional overhead of an extra GET_LBA_STATUS request
@@ -133,7 +138,7 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
if (acb->bh) {
return;
}
- acb->bh = qemu_bh_new(iscsi_bh_cb, acb);
+ acb->bh = aio_bh_new(acb->iscsilun->aio_context, iscsi_bh_cb, acb);
qemu_bh_schedule(acb->bh);
}
@@ -144,6 +149,20 @@ 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 geo_rand_range(double m, double n)
+{
+ return exp(log(m) + (double)rand() /
+ (RAND_MAX / (log(n) - log(m))));
+}
+
static void
iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
void *command_data, void *opaque)
@@ -156,20 +175,38 @@ 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 =
+ geo_rand_range(iscsi_retry_times[iTask->retries - 1],
+ iscsi_retry_times[iTask->retries]);
+ 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));
}
out:
if (iTask->co) {
- iTask->bh = qemu_bh_new(iscsi_co_generic_bh_cb, iTask);
+ iTask->bh = aio_bh_new(iTask->iscsilun->aio_context,
+ iscsi_co_generic_bh_cb, iTask);
qemu_bh_schedule(iTask->bh);
}
}
@@ -178,7 +215,7 @@ static void iscsi_co_init_iscsitask(IscsiLun *iscsilun,
struct IscsiTask *iTask)
{
*iTask = (struct IscsiTask) {
.co = qemu_coroutine_self(),
- .retries = ISCSI_CMD_RETRIES,
+ .iscsilun = iscsilun,
};
}
@@ -209,7 +246,7 @@ iscsi_aio_cancel(BlockDriverAIOCB *blockacb)
iscsi_abort_task_cb, acb);
while (acb->status == -EINPROGRESS) {
- qemu_aio_wait();
+ aio_poll(iscsilun->aio_context, true);
}
}
@@ -232,11 +269,11 @@ iscsi_set_events(IscsiLun *iscsilun)
ev = POLLIN;
ev |= iscsi_which_events(iscsi);
if (ev != iscsilun->events) {
- qemu_aio_set_fd_handler(iscsi_get_fd(iscsi),
- iscsi_process_read,
- (ev & POLLOUT) ? iscsi_process_write : NULL,
- iscsilun);
-
+ aio_set_fd_handler(iscsilun->aio_context,
+ iscsi_get_fd(iscsi),
+ iscsi_process_read,
+ (ev & POLLOUT) ? iscsi_process_write : NULL,
+ iscsilun);
}
iscsilun->events = ev;
@@ -791,7 +828,7 @@ static int iscsi_ioctl(BlockDriverState *bs, unsigned long
int req, void *buf)
iscsi_aio_ioctl(bs, req, buf, ioctl_cb, &status);
while (status == -EINPROGRESS) {
- qemu_aio_wait();
+ aio_poll(iscsilun->aio_context, true);
}
return 0;
@@ -1195,6 +1232,40 @@ fail_with_err:
return NULL;
}
+static void iscsi_detach_aio_context(BlockDriverState *bs)
+{
+ IscsiLun *iscsilun = bs->opaque;
+
+ aio_set_fd_handler(iscsilun->aio_context,
+ iscsi_get_fd(iscsilun->iscsi),
+ NULL, NULL, NULL);
+ iscsilun->events = 0;
+
+ if (iscsilun->nop_timer) {
+ timer_del(iscsilun->nop_timer);
+ timer_free(iscsilun->nop_timer);
+ iscsilun->nop_timer = NULL;
+ }
+}
+
+static void iscsi_attach_aio_context(BlockDriverState *bs,
+ AioContext *new_context)
+{
+ IscsiLun *iscsilun = bs->opaque;
+
+ iscsilun->aio_context = new_context;
+ iscsi_set_events(iscsilun);
+
+#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
+ /* Set up a timer for sending out iSCSI NOPs */
+ iscsilun->nop_timer = aio_timer_new(iscsilun->aio_context,
+ QEMU_CLOCK_REALTIME, SCALE_MS,
+ iscsi_nop_timed_event, iscsilun);
+ timer_mod(iscsilun->nop_timer,
+ qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
+#endif
+}
+
/*
* We support iscsi url's on the form
* iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
@@ -1301,6 +1372,7 @@ static int iscsi_open(BlockDriverState *bs, QDict
*options, int flags,
}
iscsilun->iscsi = iscsi;
+ iscsilun->aio_context = bdrv_get_aio_context(bs);
iscsilun->lun = iscsi_url->lun;
iscsilun->has_write_same = true;
@@ -1374,11 +1446,7 @@ static int iscsi_open(BlockDriverState *bs, QDict
*options, int flags,
scsi_free_scsi_task(task);
task = NULL;
-#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
- /* Set up a timer for sending out iSCSI NOPs */
- iscsilun->nop_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
iscsi_nop_timed_event, iscsilun);
- timer_mod(iscsilun->nop_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) +
NOP_INTERVAL);
-#endif
+ iscsi_attach_aio_context(bs, iscsilun->aio_context);
/* Guess the internal cluster (page) size of the iscsi target by the means
* of opt_unmap_gran. Transfer the unmap granularity only if it has a
@@ -1422,11 +1490,7 @@ static void iscsi_close(BlockDriverState *bs)
IscsiLun *iscsilun = bs->opaque;
struct iscsi_context *iscsi = iscsilun->iscsi;
- if (iscsilun->nop_timer) {
- timer_del(iscsilun->nop_timer);
- timer_free(iscsilun->nop_timer);
- }
- qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL);
+ iscsi_detach_aio_context(bs);
iscsi_destroy_context(iscsi);
g_free(iscsilun->zeroblock);
g_free(iscsilun->allocationmap);
@@ -1530,10 +1594,7 @@ static int iscsi_create(const char *filename,
QEMUOptionParameter *options,
if (ret != 0) {
goto out;
}
- if (iscsilun->nop_timer) {
- timer_del(iscsilun->nop_timer);
- timer_free(iscsilun->nop_timer);
- }
+ iscsi_detach_aio_context(bs);
if (iscsilun->type != TYPE_DISK) {
ret = -ENODEV;
goto out;
--
1.7.9.5
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Qemu-devel] [PATCHv2] block/iscsi: handle BUSY condition,
Peter Lieven <=