| Message ID | b5c4060a-45cc-d83a-d552-89db3283d394@kamp.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/25/2017 12:55 PM, Peter Lieven wrote: > Am 24.04.2017 um 22:13 schrieb Anton Nefedov: >> >> On 24/04/2017 21:16, Peter Lieven wrote: >>> >>> >>>> Am 24.04.2017 um 18:27 schrieb Anton Nefedov >>>> <anton.nefedov@virtuozzo.com>: >>>> >>>>> On 04/21/2017 03:37 PM, Peter Lieven wrote: >>>>>> Am 21.04.2017 um 14:19 schrieb Anton Nefedov: >>>>>>> On 04/21/2017 01:44 PM, Peter Lieven wrote: >>>>>>>> Am 21.04.2017 um 12:04 schrieb Anton Nefedov: >>>>>>>> On error path (like i/o error in one of the coroutines), it's >>>>>>>> required to >>>>>>>> - wait for coroutines completion before cleaning the common >>>>>>>> structures >>>>>>>> - reenter dependent coroutines so they ever finish >>>>>>>> >>>>>>>> Introduced in 2d9187bc65. >>>>>>>> >>>>>>>> Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com> >>>>>>>> --- >>>>>>>> [..] >>>>>>>> >>>>>>> >>>>>>> >>>>>>> And what if we error out in the read path? Wouldn't be something >>>>>>> like this easier? >>>>>>> >>>>>>> >>>>>>> diff --git a/qemu-img.c b/qemu-img.c >>>>>>> index 22f559a..4ff1085 100644 >>>>>>> --- a/qemu-img.c >>>>>>> +++ b/qemu-img.c >>>>>>> @@ -1903,6 +1903,16 @@ static int convert_do_copy(ImgConvertState >>>>>>> *s) >>>>>>> main_loop_wait(false); >>>>>>> } >>>>>>> >>>>>>> + /* on error path we need to enter all coroutines that are still >>>>>>> + * running before cleaning up common structures */ >>>>>>> + if (s->ret) { >>>>>>> + for (i = 0; i < s->num_coroutines; i++) { >>>>>>> + if (s->co[i]) { >>>>>>> + qemu_coroutine_enter(s->co[i]); >>>>>>> + } >>>>>>> + } >>>>>>> + } >>>>>>> + >>>>>>> if (s->compressed && !s->ret) { >>>>>>> /* signal EOF to align */ >>>>>>> ret = blk_pwrite_compressed(s->target, 0, NULL, 0); >>>>>>> >>>>>>> >>>>>>> Peter >>>>>>> >>>>>> >>>>>> seemed a bit too daring to me to re-enter every coroutine >>>>>> potentially including the ones that yielded waiting for I/O >>>>>> completion. >>>>>> If that's ok - that is for sure easier :) >>>>> >>>>> I think we should enter every coroutine that is still running and >>>>> have it terminate correctly. It was my mistake that I have not >>>>> done this in the original patch. Can you check if the above fixes >>>>> your test cases that triggered the bug? >>>>> >>>> >>>> hi, sorry I'm late with the answer >>>> >>>> this segfaults in bdrv_close(). Looks like it tries to finish some >>>> i/o which coroutine we have already entered and terminated? >>>> >>>> (gdb) run >>>> Starting program: /vz/anefedov/qemu-build/us/./qemu-img convert -O >>>> [..] >>>> >>>> >>>>> Peter >>>>> >>>> >>>> /Anton >>>> >>> >>> it seems that this is a bit tricky, can you share how your test case >>> works? >>> >>> thanks, >>> peter >>> >> >> how I tested today was basically >> >> diff --git a/qemu-img.c b/qemu-img.c >> index 4425aaa..3d2d506 100644 >> --- a/qemu-img.c >> +++ b/qemu-img.c >> @@ -1788,6 +1788,10 @@ static void coroutine_fn >> convert_co_do_copy(void *opaque) >> >> if (status == BLK_DATA) { >> ret = convert_co_read(s, sector_num, n, buf); >> + const uint64_t fsector = 10*1024*1024/512; >> + if (sector_num <= fsector && fsector < sector_num+n) { >> + ret = -EIO; >> + } >> if (ret < 0) { >> error_report("error while reading sector %" PRId64 >> ": %s", sector_num, strerror(-ret)); >> > > I ended up with sth similar to your approach. Can you check this? > > > Thanks, > > Peter > > > diff --git a/qemu-img.c b/qemu-img.c > index b94fc11..ed9ce9e 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -1761,13 +1761,13 @@ static void coroutine_fn convert_co_do_copy(void > *opaque) > qemu_co_mutex_lock(&s->lock); > if (s->ret != -EINPROGRESS || s->sector_num >= s->total_sectors) { > qemu_co_mutex_unlock(&s->lock); > - goto out; > + break; > } > n = convert_iteration_sectors(s, s->sector_num); > if (n < 0) { > qemu_co_mutex_unlock(&s->lock); > s->ret = n; > - goto out; > + break; > } > /* save current sector and allocation status to local variables */ > sector_num = s->sector_num; > @@ -1792,7 +1792,6 @@ static void coroutine_fn convert_co_do_copy(void > *opaque) > error_report("error while reading sector %" PRId64 > ": %s", sector_num, strerror(-ret)); > s->ret = ret; > - goto out; > } > } else if (!s->min_sparse && status == BLK_ZERO) { > status = BLK_DATA; > @@ -1801,22 +1800,20 @@ static void coroutine_fn convert_co_do_copy(void > *opaque) > > if (s->wr_in_order) { > /* keep writes in order */ > - while (s->wr_offs != sector_num) { > - if (s->ret != -EINPROGRESS) { > - goto out; > - } > + while (s->wr_offs != sector_num && s->ret == -EINPROGRESS) { > s->wait_sector_num[index] = sector_num; > qemu_coroutine_yield(); > } > s->wait_sector_num[index] = -1; > } > > - ret = convert_co_write(s, sector_num, n, buf, status); > - if (ret < 0) { > - error_report("error while writing sector %" PRId64 > - ": %s", sector_num, strerror(-ret)); > - s->ret = ret; > - goto out; > + if (s->ret == -EINPROGRESS) { > + ret = convert_co_write(s, sector_num, n, buf, status); > + if (ret < 0) { > + error_report("error while writing sector %" PRId64 > + ": %s", sector_num, strerror(-ret)); > + s->ret = ret; > + } > } > > if (s->wr_in_order) { > @@ -1837,7 +1834,6 @@ static void coroutine_fn convert_co_do_copy(void > *opaque) > } > } > > -out: > qemu_vfree(buf); > s->co[index] = NULL; > s->running_coroutines--; > @@ -1899,7 +1895,7 @@ static int convert_do_copy(ImgConvertState *s) > qemu_coroutine_enter(s->co[i]); > } > > - while (s->ret == -EINPROGRESS) { > + while (s->running_coroutines) { > main_loop_wait(false); > } > > This one seems to work; I've been running for several hours qemu-img convert from nbd which spontaneously fails in ~ every 2nd convert; and yet qemu-img keeps terminating smoothly /Anton
Am 25.04.2017 um 11:55 schrieb Peter Lieven: > Am 24.04.2017 um 22:13 schrieb Anton Nefedov: >> >> On 24/04/2017 21:16, Peter Lieven wrote: >>> >>> >>>> Am 24.04.2017 um 18:27 schrieb Anton Nefedov <anton.nefedov@virtuozzo.com>: >>>> >>>>> On 04/21/2017 03:37 PM, Peter Lieven wrote: >>>>>> Am 21.04.2017 um 14:19 schrieb Anton Nefedov: >>>>>>> On 04/21/2017 01:44 PM, Peter Lieven wrote: >>>>>>>> Am 21.04.2017 um 12:04 schrieb Anton Nefedov: >>>>>>>> On error path (like i/o error in one of the coroutines), it's required to >>>>>>>> - wait for coroutines completion before cleaning the common structures >>>>>>>> - reenter dependent coroutines so they ever finish >>>>>>>> >>>>>>>> Introduced in 2d9187bc65. >>>>>>>> >>>>>>>> Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com> >>>>>>>> --- >>>>>>>> [..] >>>>>>>> >>>>>>> >>>>>>> >>>>>>> And what if we error out in the read path? Wouldn't be something like this easier? >>>>>>> >>>>>>> >>>>>>> diff --git a/qemu-img.c b/qemu-img.c >>>>>>> index 22f559a..4ff1085 100644 >>>>>>> --- a/qemu-img.c >>>>>>> +++ b/qemu-img.c >>>>>>> @@ -1903,6 +1903,16 @@ static int convert_do_copy(ImgConvertState *s) >>>>>>> main_loop_wait(false); >>>>>>> } >>>>>>> >>>>>>> + /* on error path we need to enter all coroutines that are still >>>>>>> + * running before cleaning up common structures */ >>>>>>> + if (s->ret) { >>>>>>> + for (i = 0; i < s->num_coroutines; i++) { >>>>>>> + if (s->co[i]) { >>>>>>> + qemu_coroutine_enter(s->co[i]); >>>>>>> + } >>>>>>> + } >>>>>>> + } >>>>>>> + >>>>>>> if (s->compressed && !s->ret) { >>>>>>> /* signal EOF to align */ >>>>>>> ret = blk_pwrite_compressed(s->target, 0, NULL, 0); >>>>>>> >>>>>>> >>>>>>> Peter >>>>>>> >>>>>> >>>>>> seemed a bit too daring to me to re-enter every coroutine potentially including the ones that yielded waiting for I/O completion. >>>>>> If that's ok - that is for sure easier :) >>>>> >>>>> I think we should enter every coroutine that is still running and have it terminate correctly. It was my mistake that I have not >>>>> done this in the original patch. Can you check if the above fixes your test cases that triggered the bug? >>>>> >>>> >>>> hi, sorry I'm late with the answer >>>> >>>> this segfaults in bdrv_close(). Looks like it tries to finish some i/o which coroutine we have already entered and terminated? >>>> >>>> (gdb) run >>>> Starting program: /vz/anefedov/qemu-build/us/./qemu-img convert -O qcow2 ./harddisk.hdd.c ./harddisk.hdd >>>> [Thread debugging using libthread_db enabled] >>>> Using host libthread_db library "/lib64/libthread_db.so.1". >>>> [New Thread 0x7fffeac2d700 (LWP 436020)] >>>> [New Thread 0x7fffe4ed6700 (LWP 436021)] >>>> qemu-img: error while reading sector 20480: Input/output error >>>> qemu-img: error while writing sector 19712: Operation now in progress >>>> >>>> Program received signal SIGSEGV, Segmentation fault. >>>> aio_co_wake (co=0x0) at /mnt/code/us-qemu/util/async.c:454 >>>> 454 ctx = atomic_read(&co->ctx); >>>> (gdb) bt >>>> #0 aio_co_wake (co=0x0) at /mnt/code/us-qemu/util/async.c:454 >>>> /* [Anton]: thread_pool_co_cb () here */ >>>> #1 0x0000555555634629 in thread_pool_completion_bh (opaque=0x555555cfe020) at /mnt/code/us-qemu/util/thread-pool.c:189 >>>> #2 0x0000555555633b31 in aio_bh_call (bh=0x555555cfe0f0) at /mnt/code/us-qemu/util/async.c:90 >>>> #3 aio_bh_poll (ctx=ctx@entry=0x555555cee6d0) at /mnt/code/us-qemu/util/async.c:118 >>>> #4 0x0000555555636f14 in aio_poll (ctx=ctx@entry=0x555555cee6d0, blocking=<optimized out>) at /mnt/code/us-qemu/util/aio-posix.c:682 >>>> #5 0x00005555555c52d4 in bdrv_drain_recurse (bs=bs@entry=0x555555d22560) at /mnt/code/us-qemu/block/io.c:164 >>>> #6 0x00005555555c5aed in bdrv_drained_begin (bs=bs@entry=0x555555d22560) at /mnt/code/us-qemu/block/io.c:248 >>>> #7 0x0000555555581443 in bdrv_close (bs=0x555555d22560) at /mnt/code/us-qemu/block.c:2909 >>>> #8 bdrv_delete (bs=0x555555d22560) at /mnt/code/us-qemu/block.c:3100 >>>> #9 bdrv_unref (bs=0x555555d22560) at /mnt/code/us-qemu/block.c:4087 >>>> #10 0x00005555555baf44 in blk_remove_bs (blk=blk@entry=0x555555d22380) at /mnt/code/us-qemu/block/block-backend.c:552 >>>> #11 0x00005555555bb173 in blk_delete (blk=0x555555d22380) at /mnt/code/us-qemu/block/block-backend.c:238 >>>> #12 blk_unref (blk=blk@entry=0x555555d22380) at /mnt/code/us-qemu/block/block-backend.c:282 >>>> #13 0x000055555557a22c in img_convert (argc=<optimized out>, argv=<optimized out>) at /mnt/code/us-qemu/qemu-img.c:2359 >>>> #14 0x0000555555574189 in main (argc=5, argv=0x7fffffffe4a0) at /mnt/code/us-qemu/qemu-img.c:4464 >>>> >>>> >>>>> Peter >>>>> >>>> >>>> /Anton >>>> >>> >>> it seems that this is a bit tricky, can you share how your test case works? >>> >>> thanks, >>> peter >>> >> >> how I tested today was basically >> >> diff --git a/qemu-img.c b/qemu-img.c >> index 4425aaa..3d2d506 100644 >> --- a/qemu-img.c >> +++ b/qemu-img.c >> @@ -1788,6 +1788,10 @@ static void coroutine_fn convert_co_do_copy(void *opaque) >> >> if (status == BLK_DATA) { >> ret = convert_co_read(s, sector_num, n, buf); >> + const uint64_t fsector = 10*1024*1024/512; >> + if (sector_num <= fsector && fsector < sector_num+n) { >> + ret = -EIO; >> + } >> if (ret < 0) { >> error_report("error while reading sector %" PRId64 >> ": %s", sector_num, strerror(-ret)); >> > > I ended up with sth similar to your approach. Can you check this? > > > Thanks, > > Peter > > > diff --git a/qemu-img.c b/qemu-img.c > index b94fc11..ed9ce9e 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -1761,13 +1761,13 @@ static void coroutine_fn convert_co_do_copy(void *opaque) > qemu_co_mutex_lock(&s->lock); > if (s->ret != -EINPROGRESS || s->sector_num >= s->total_sectors) { > qemu_co_mutex_unlock(&s->lock); > - goto out; > + break; > } > n = convert_iteration_sectors(s, s->sector_num); > if (n < 0) { > qemu_co_mutex_unlock(&s->lock); > s->ret = n; > - goto out; > + break; > } > /* save current sector and allocation status to local variables */ > sector_num = s->sector_num; > @@ -1792,7 +1792,6 @@ static void coroutine_fn convert_co_do_copy(void *opaque) > error_report("error while reading sector %" PRId64 > ": %s", sector_num, strerror(-ret)); > s->ret = ret; > - goto out; > } > } else if (!s->min_sparse && status == BLK_ZERO) { > status = BLK_DATA; > @@ -1801,22 +1800,20 @@ static void coroutine_fn convert_co_do_copy(void *opaque) > > if (s->wr_in_order) { > /* keep writes in order */ > - while (s->wr_offs != sector_num) { > - if (s->ret != -EINPROGRESS) { > - goto out; > - } > + while (s->wr_offs != sector_num && s->ret == -EINPROGRESS) { > s->wait_sector_num[index] = sector_num; > qemu_coroutine_yield(); > } > s->wait_sector_num[index] = -1; > } > > - ret = convert_co_write(s, sector_num, n, buf, status); > - if (ret < 0) { > - error_report("error while writing sector %" PRId64 > - ": %s", sector_num, strerror(-ret)); > - s->ret = ret; > - goto out; > + if (s->ret == -EINPROGRESS) { > + ret = convert_co_write(s, sector_num, n, buf, status); > + if (ret < 0) { > + error_report("error while writing sector %" PRId64 > + ": %s", sector_num, strerror(-ret)); > + s->ret = ret; > + } > } > > if (s->wr_in_order) { > @@ -1837,7 +1834,6 @@ static void coroutine_fn convert_co_do_copy(void *opaque) > } > } > > -out: > qemu_vfree(buf); > s->co[index] = NULL; > s->running_coroutines--; > @@ -1899,7 +1895,7 @@ static int convert_do_copy(ImgConvertState *s) > qemu_coroutine_enter(s->co[i]); > } > > - while (s->ret == -EINPROGRESS) { > + while (s->running_coroutines) { > main_loop_wait(false); > } > > Great. Shall we take this one? I would prefer it because it avoids the separate convert_reenter_waiting function. If you want you can take my code and submit a V3. Peter
diff --git a/qemu-img.c b/qemu-img.c index b94fc11..ed9ce9e 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1761,13 +1761,13 @@ static void coroutine_fn convert_co_do_copy(void *opaque) qemu_co_mutex_lock(&s->lock); if (s->ret != -EINPROGRESS || s->sector_num >= s->total_sectors) { qemu_co_mutex_unlock(&s->lock); - goto out; + break; } n = convert_iteration_sectors(s, s->sector_num); if (n < 0) { qemu_co_mutex_unlock(&s->lock); s->ret = n; - goto out; + break; } /* save current sector and allocation status to local variables */ sector_num = s->sector_num; @@ -1792,7 +1792,6 @@ static void coroutine_fn convert_co_do_copy(void *opaque) error_report("error while reading sector %" PRId64 ": %s", sector_num, strerror(-ret)); s->ret = ret; - goto out; } } else if (!s->min_sparse && status == BLK_ZERO) { status = BLK_DATA; @@ -1801,22 +1800,20 @@ static void coroutine_fn convert_co_do_copy(void *opaque) if (s->wr_in_order) { /* keep writes in order */ - while (s->wr_offs != sector_num) { - if (s->ret != -EINPROGRESS) { - goto out; - } + while (s->wr_offs != sector_num && s->ret == -EINPROGRESS) { s->wait_sector_num[index] = sector_num; qemu_coroutine_yield(); } s->wait_sector_num[index] = -1; } - ret = convert_co_write(s, sector_num, n, buf, status); - if (ret < 0) { - error_report("error while writing sector %" PRId64 - ": %s", sector_num, strerror(-ret)); - s->ret = ret; - goto out; + if (s->ret == -EINPROGRESS) { + ret = convert_co_write(s, sector_num, n, buf, status); + if (ret < 0) { + error_report("error while writing sector %" PRId64 + ": %s", sector_num, strerror(-ret)); + s->ret = ret; + } } if (s->wr_in_order) { @@ -1837,7 +1834,6 @@ static void coroutine_fn convert_co_do_copy(void *opaque) } } -out: qemu_vfree(buf); s->co[index] = NULL; s->running_coroutines--; @@ -1899,7 +1895,7 @@ static int convert_do_copy(ImgConvertState *s) qemu_coroutine_enter(s->co[i]); } - while (s->ret == -EINPROGRESS) { + while (s->running_coroutines) { main_loop_wait(false); }