[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PULL 09/11] block: Use bdrv_coroutine_enter to start I/O c
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PULL 09/11] block: Use bdrv_coroutine_enter to start I/O coroutines |
Date: |
Tue, 11 Apr 2017 20:26:30 +0800 |
BDRV_POLL_WHILE waits for the started I/O by releasing bs's ctx then polling
the main context, which relies on the yielded coroutine continuing on bs->ctx
before notifying qemu_aio_context with bdrv_wakeup().
Thus, using qemu_coroutine_enter to start I/O is wrong because if the coroutine
is entered from main loop, co->ctx will be qemu_aio_context, as a result of the
"release, poll, acquire" loop of BDRV_POLL_WHILE, race conditions happen when
both main thread and the iothread access the same BDS:
main loop iothread
-----------------------------------------------------------------------
blockdev_snapshot
aio_context_acquire(bs->ctx)
virtio_scsi_data_plane_handle_cmd
bdrv_drained_begin(bs->ctx)
bdrv_flush(bs)
bdrv_co_flush(bs) aio_context_acquire(bs->ctx).enter
...
qemu_coroutine_yield(co)
BDRV_POLL_WHILE()
aio_context_release(bs->ctx)
aio_context_acquire(bs->ctx).return
...
aio_co_wake(co)
aio_poll(qemu_aio_context) ...
co_schedule_bh_cb() ...
qemu_coroutine_enter(co) ...
/* (A) bdrv_co_flush(bs) /* (B) I/O on bs */
continues... */
aio_context_release(bs->ctx)
aio_context_acquire(bs->ctx)
Note that in above case, bdrv_drained_begin() doesn't do the "release,
poll, acquire" in BDRV_POLL_WHILE, because bs->in_flight == 0.
Fix this by using bdrv_coroutine_enter and enter coroutine in the right
context.
iotests 109 output is updated because the coroutine reenter flow during
mirror job complete is different (now through co_queue_wakeup, instead
of the unconditional qemu_coroutine_switch before), making the end job
len different.
Signed-off-by: Fam Zheng <address@hidden>
Acked-by: Stefan Hajnoczi <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
---
block/block-backend.c | 4 ++--
block/io.c | 14 +++++++-------
tests/qemu-iotests/109.out | 10 +++++-----
3 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index 18ece99..a8f2b34 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1045,7 +1045,7 @@ static int blk_prw(BlockBackend *blk, int64_t offset,
uint8_t *buf,
co_entry(&rwco);
} else {
Coroutine *co = qemu_coroutine_create(co_entry, &rwco);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(blk_bs(blk), co);
BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
}
@@ -1152,7 +1152,7 @@ static BlockAIOCB *blk_aio_prwv(BlockBackend *blk,
int64_t offset, int bytes,
acb->has_returned = false;
co = qemu_coroutine_create(co_entry, acb);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(blk_bs(blk), co);
acb->has_returned = true;
if (acb->rwco.ret != NOT_DONE) {
diff --git a/block/io.c b/block/io.c
index 9598646..00e45ca 100644
--- a/block/io.c
+++ b/block/io.c
@@ -616,7 +616,7 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
bdrv_rw_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(child->bs, co);
BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
}
return rwco.ret;
@@ -1880,7 +1880,7 @@ int64_t bdrv_get_block_status_above(BlockDriverState *bs,
} else {
co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry,
&data);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, !data.done);
}
return data.ret;
@@ -2006,7 +2006,7 @@ bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
int64_t pos,
};
Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(bs, co);
while (data.ret == -EINPROGRESS) {
aio_poll(bdrv_get_aio_context(bs), true);
}
@@ -2223,7 +2223,7 @@ static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild
*child,
acb->is_write = is_write;
co = qemu_coroutine_create(bdrv_co_do_rw, acb);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(child->bs, co);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
@@ -2254,7 +2254,7 @@ BlockAIOCB *bdrv_aio_flush(BlockDriverState *bs,
acb->req.error = -EINPROGRESS;
co = qemu_coroutine_create(bdrv_aio_flush_co_entry, acb);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(bs, co);
bdrv_co_maybe_schedule_bh(acb);
return &acb->common;
@@ -2387,7 +2387,7 @@ int bdrv_flush(BlockDriverState *bs)
bdrv_flush_co_entry(&flush_co);
} else {
co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE);
}
@@ -2534,7 +2534,7 @@ int bdrv_pdiscard(BlockDriverState *bs, int64_t offset,
int count)
bdrv_pdiscard_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco);
- qemu_coroutine_enter(co);
+ bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, rwco.ret == NOT_DONE);
}
diff --git a/tests/qemu-iotests/109.out b/tests/qemu-iotests/109.out
index e5d70d7..55fe536 100644
--- a/tests/qemu-iotests/109.out
+++ b/tests/qemu-iotests/109.out
@@ -10,7 +10,7 @@ Automatically detecting the format is dangerous for raw
images, write operations
Specify the 'raw' format explicitly to remove the restrictions.
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action":
"report"}}
-{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 1024, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
{"return": []}
read 65536/65536 bytes at offset 0
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -73,7 +73,7 @@ Automatically detecting the format is dangerous for raw
images, write operations
Specify the 'raw' format explicitly to remove the restrictions.
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action":
"report"}}
-{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 1024, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
{"return": []}
read 65536/65536 bytes at offset 0
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -115,7 +115,7 @@ Automatically detecting the format is dangerous for raw
images, write operations
Specify the 'raw' format explicitly to remove the restrictions.
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action":
"report"}}
-{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2560, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
{"return": []}
read 65536/65536 bytes at offset 0
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -135,7 +135,7 @@ Automatically detecting the format is dangerous for raw
images, write operations
Specify the 'raw' format explicitly to remove the restrictions.
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action":
"report"}}
-{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2560, "offset": OFFSET,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset":
OFFSET, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
{"return": []}
read 65536/65536 bytes at offset 0
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -195,7 +195,7 @@ Automatically detecting the format is dangerous for raw
images, write operations
Specify the 'raw' format explicitly to remove the restrictions.
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action":
"report"}}
-{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2048, "offset": OFFSET,
"speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
"BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset":
OFFSET, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
{"return": []}
read 65536/65536 bytes at offset 0
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
--
2.9.3
- [Qemu-devel] [PULL 00/11] Block patches for 2.9-rc4, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 01/11] block: Make bdrv_parent_drained_begin/end public, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 02/11] block: Quiesce old aio context during bdrv_set_aio_context, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 03/11] tests/block-job-txn: Don't start block job before adding to txn, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 04/11] coroutine: Extract qemu_aio_coroutine_enter, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 05/11] async: Introduce aio_co_enter, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 06/11] block: Introduce bdrv_coroutine_enter, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 07/11] blockjob: Use bdrv_coroutine_enter to start coroutine, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 08/11] qemu-io-cmds: Use bdrv_coroutine_enter, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 09/11] block: Use bdrv_coroutine_enter to start I/O coroutines,
Fam Zheng <=
- [Qemu-devel] [PULL 11/11] sheepdog: Use bdrv_coroutine_enter before BDRV_POLL_WHILE, Fam Zheng, 2017/04/11
- [Qemu-devel] [PULL 10/11] block: Fix bdrv_co_flush early return, Fam Zheng, 2017/04/11
- Re: [Qemu-devel] [PULL 00/11] Block patches for 2.9-rc4, Peter Maydell, 2017/04/11