[tapdisk2][PATCH1/1] Fix vreq with error of -EBUSY fails 100 times too soon

["gordongong0350@gmail.com" <gordongong0350@gmail.com>]

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Fix vreq with error of -EBUSY fails 100 times too soon, ?that?return EIO to td device layer. If this tddevice request is metadata of filesystem, the result is not good at all.
To reproduce it witch ?"./iozone -I -s 2G -r 512k -r 1m -r 2m -r 4m -i 0 -i 1 -f /data/iozone_test.tmp",the result is input/output error & iozone is stopped.



From ccc0ce3aede1f5c920036847ddb16b25969be7ba Mon Sep 17 00:00:00 2001From: Xiaodong Gong <gordongong0350@gmail.com>Date: Fri, 28 Feb 2014 03:01:19 -0500Subject: [PATCH] fix vreq with error of -EBUSY fails 100 times too soon,?return EIO to td device layer.
1) all free list is consumed by vreq in one or two block that? ?is seted in bat entry.2) vreq in fail queue, get a chance to run quickly, such as 90us.---?tools/blktap2/drivers/tapdisk-vbd.c | 17 ++++++++++++++---?tools/blktap2/drivers/tapdisk-vbd.h | ?1 +?2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/tools/blktap2/drivers/tapdisk-vbd.c b/tools/blktap2/drivers/tapdisk-vbd.cindex c665f27..529eb91 100644--- a/tools/blktap2/drivers/tapdisk-vbd.c+++ b/tools/blktap2/drivers/tapdisk-vbd.c@@ -1081,7 +1081,7 @@ tapdisk_vbd_check_state(td_vbd_t *vbd)?	td_vbd_request_t *vreq, *tmp;??	tapdisk_vbd_for_each_request(vreq, tmp, &vbd->failed_requests)-		if (vreq->num_retries >= TD_VBD_MAX_RETRIES)+		if (vreq->num_retries >= TD_VBD_MAX_RETRIES && vreq->busy_looping != 1 )?			tapdisk_vbd_complete_vbd_request(vbd, vreq);??	if (!list_empty(&vbd->new_requests) ||@@ -1168,7 +1168,7 @@ tapdisk_vbd_complete_vbd_request(td_vbd_t *vbd, td_vbd_request_t *vreq)?{?	if (!vreq->submitting && !vreq->secs_pending) {?		if (vreq->status == BLKIF_RSP_ERROR &&-		?? ?vreq->num_retries < TD_VBD_MAX_RETRIES &&+		?? ?(vreq->num_retries < TD_VBD_MAX_RETRIES || vreq->busy_looping == 1)&&?		?? ?!td_flag_test(vbd->state, TD_VBD_DEAD) &&?		?? ?!td_flag_test(vbd->state, TD_VBD_SHUTDOWN_REQUESTED))?			tapdisk_vbd_move_request(vreq, &vbd->failed_requests);@@ -1450,17 +1450,28 @@ tapdisk_vbd_reissue_failed_requests(td_vbd_t *vbd)?	gettimeofday(&now, NULL);??	tapdisk_vbd_for_each_request(vreq, tmp, &vbd->failed_requests) {+		uint64_t delta = 0;+?		if (vreq->secs_pending)?			continue;??		if (td_flag_test(vbd->state, TD_VBD_SHUTDOWN_REQUESTED))?			goto fail;?+		if (vreq->num_retries > TD_VBD_MAX_RETRIES - 10) {+			delta = (now.tv_sec - vreq->last_try.tv_sec) * 1000000\+				+ now.tv_usec - vreq->last_try.tv_usec;+			if (delta * vreq->num_retries < TD_VBD_RETRY_INTERVAL)+				vreq->busy_looping = 1;+			else+				vreq->busy_looping = 0;+		}+?		if (vreq->error != -EBUSY &&?		?? ?now.tv_sec - vreq->last_try.tv_sec < TD_VBD_RETRY_INTERVAL)?			continue;?-		if (vreq->num_retries >= TD_VBD_MAX_RETRIES) {+		if (vreq->num_retries >= TD_VBD_MAX_RETRIES && vreq->busy_looping != 1) {?		fail:?			DBG(TLOG_INFO, "req %"PRIu64"retried %d times\n",?			?? ?vreq->req.id, vreq->num_retries);diff --git a/tools/blktap2/drivers/tapdisk-vbd.h b/tools/blktap2/drivers/tapdisk-vbd.hindex be084b2..9e5f5f6 100644--- a/tools/blktap2/drivers/tapdisk-vbd.h+++ b/tools/blktap2/drivers/tapdisk-vbd.h@@ -73,6 +73,7 @@ struct td_vbd_request {?	int ? ? ? ? ? ? ? ? ? ? ? ? submitting;?	int ? ? ? ? ? ? ? ? ? ? ? ? secs_pending;?	int ? ? ? ? ? ? ? ? ? ? ? ? num_retries;+	int ? ? ? ? ? ? ? ? ? ? ? ? busy_looping;?	struct timeval ? ? ? ? ? ? ?last_try;??	td_vbd_t ? ? ? ? ? ? ? ? ? *vbd;--?1.8.3.1


gordongong0350@gmail.com

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